WO2020079817A1 - Power conversion device, power conversion system, power conversion method, and program - Google Patents

Power conversion device, power conversion system, power conversion method, and program Download PDF

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Publication number
WO2020079817A1
WO2020079817A1 PCT/JP2018/038886 JP2018038886W WO2020079817A1 WO 2020079817 A1 WO2020079817 A1 WO 2020079817A1 JP 2018038886 W JP2018038886 W JP 2018038886W WO 2020079817 A1 WO2020079817 A1 WO 2020079817A1
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WIPO (PCT)
Prior art keywords
frequency
triangular wave
voltage
carrier signal
wave carrier
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PCT/JP2018/038886
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French (fr)
Japanese (ja)
Inventor
慧 関口
卓郎 新井
崇裕 石黒
Original Assignee
株式会社東芝
東芝エネルギーシステムズ株式会社
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Application filed by 株式会社東芝, 東芝エネルギーシステムズ株式会社 filed Critical 株式会社東芝
Priority to PCT/JP2018/038886 priority Critical patent/WO2020079817A1/en
Priority to JP2019507883A priority patent/JP6622442B1/en
Publication of WO2020079817A1 publication Critical patent/WO2020079817A1/en

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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483Converters with outputs that each can have more than two voltages levels
    • H02M7/49Combination of the output voltage waveforms of a plurality of converters

Definitions

  • the embodiment of the present invention relates to a power conversion device, a power conversion system, a power conversion method, and a program.
  • the MMC converter is a power conversion device that includes an arm unit that includes a plurality of unit converters connected in series, and is capable of handling high voltage and large capacity by adding the voltages that can be output from each unit converter. is there.
  • the power conversion device is connected between, for example, an AC system and a DC system, and converts power.
  • the MMC converter when the MMC converter includes a unit converter that is a half-bridge cell type two-level converter, switching control of the unit converter uses a triangular wave carrier as a modulation method for generating a PWM (Pulse Width Modulation) voltage.
  • a comparison method may be used.
  • the frequency of the triangular wave carrier signal that is, the switching frequency of the unit converter
  • the capacitor of the half bridge cell is It may be difficult to stabilize the voltage balance. Therefore, conventionally, there is known a technique of setting the triangular wave carrier frequency to a non-integer multiple of about 2 to less than 4 times the AC system frequency or increasing the frequency to 4 times or more.
  • the switching frequency per unit converter becomes high, the scale of power loss accompanying power conversion becomes large. Therefore, when the triangular wave carrier frequency is set to a high frequency that is four times or more as high as the AC system frequency, It is difficult to reduce the loss due to the power conversion of the conversion device. On the other hand, if a non-integer multiple of less than 4 times the AC system frequency is set from the viewpoint of lowering the loss, the control performance of voltage and current deteriorates because of the low frequency. Therefore, when a system failure occurs in the AC system or DC system to be interconnected, it may be difficult for the power conversion device to continue operating.
  • An object of the present invention is to provide a power conversion device, a power conversion system, a power conversion method, and a program that can improve the operation continuity at the time of a system fault while reducing the power loss related to power conversion. To do.
  • An object of the present invention is to provide a power conversion device, a power conversion system, a power conversion method, and a program capable of improving the operation continuity at the time of a system fault while reducing the power loss related to power conversion. Is to provide.
  • the power converter of the embodiment is a power converter capable of mutually converting DC and AC, and has an arm unit, a generation unit, a control unit, and a switching unit.
  • the arm unit is connected in series with at least one unit converter including a capacitor and a switching element that are connected in parallel with each other.
  • the generating unit includes a first frequency obtained by multiplying the alternating current frequency by a first non-integer value, a second frequency obtained by multiplying the alternating current frequency by a second non-integer value equal to or greater than the first non-integer value, and the second frequency.
  • a triangular wave carrier signal of any one of the third frequency, which is a frequency higher than two frequencies, is selectively generated.
  • the control unit controls the switching element based on the triangular wave carrier signal generated by the generation unit.
  • the switching unit switches to which frequency the triangular wave carrier signal is generated by the generation unit, and when the absolute value of the AC voltage is in a predetermined range, the switching unit switches the triangular wave carrier of the first frequency.
  • the triangular wave carrier signal of the third frequency is generated for the first period, and the absolute value of the alternating voltage is within the predetermined range.
  • the generator does not generate the triangular wave carrier signal of the third frequency, the triangular wave carrier signal of the second frequency is generated during the second period.
  • FIG. 1 is a diagram illustrating an example of a configuration of a power conversion device 1 according to an embodiment.
  • the power conversion device 1 is provided at an interconnection point between an AC system and a DC system, and mutually converts AC power supplied by the AC system and DC power supplied by the DC system.
  • the power conversion device 1 includes a power converter 10 and a converter control device 20.
  • the power converter 10 mutually converts AC power and DC power under the control of the converter control device 20.
  • the power converter 10 is, for example, a modular multilevel converter (hereinafter, MMC converter: Modular Multilevel Converter).
  • FIG. 2 is a diagram showing an example of the configuration of the power converter 10.
  • the power converter 10 includes a plurality of legs LG between a positive electrode of the DC system (a terminal P shown in the figure) and a negative electrode of the DC system (a terminal N shown in the figure).
  • the number of legs LG corresponds, for example, to the number of phases of AC power supplied by the AC system.
  • the AC system supplies three-phase three-wire AC power of a first phase (R phase shown), a second phase (S phase shown), and a third phase (T phase shown). Therefore, the power converter 10 includes the leg LGr corresponding to the R phase, the leg LGs corresponding to the S phase, and the leg LGt corresponding to the T phase.
  • leg LG when the leg LGr, the leg LGs, and the leg LGt are not distinguished from each other, they are collectively referred to as “leg LG”.
  • a certain phase of the three phases of AC power supplied by the AC system is connected to the leg LG via a transformer (a transformer TR shown in the figure).
  • the leg LGr is connected to the R phase
  • the leg LGs is connected to the S phase
  • the leg LGt is connected to the T phase.
  • a connection point between the leg LGr and the R phase will be referred to as a connection point CPr
  • a connection point between the leg LGs and the S phase will be referred to as a connection point CPs
  • a connection between the leg LGt and the T phase will be described.
  • the point is described as a connection point CPt.
  • the connection point CPr, the connection point CPs, and the connection point CPt are not distinguished from each other, they are simply referred to as the connection point CP.
  • a portion having the same potential as the terminal P of the DC voltage output by the power converter 10 is also referred to as a terminal P of the leg LG, and a portion having the same potential as the terminal N of the DC voltage, Also referred to as the terminal N of the leg LG.
  • a portion from the terminal P of the leg LG to the connection point of each phase is also referred to as a positive arm unit.
  • a portion from the connection point of each phase to the terminal N of the leg LG is also described as a negative arm unit.
  • Each leg LG has the same configuration as each other.
  • the configuration related to the leg LGr is suffixed with “r”
  • the configuration related to the leg LGs is suffixed with “s”
  • the configuration related to the leg LGt is suffixed to , "T” is added to the end of the code.
  • “r”, “s”, or “t” is omitted.
  • the leg LGr will be described on behalf of each leg LG.
  • the leg LGr includes n cells CL (the illustrated cells CL1-1r to CL1-nr and cells CL2-1r to CL2-nr) and a plurality of reactors in the positive arm unit and the negative arm unit, respectively.
  • RT reactors RT1r, RT2r shown.
  • n is a natural number.
  • the cells CL1-1r to CL1-nr and the reactor RT1r are connected in series in the stated order from the terminal P toward the connection point CPr.
  • a reactor RT2r and cells CL2-1r to CL2-nr are connected in series from the connection point CPr to the terminal N in the negative arm unit of the leg LGr in the order shown.
  • the reactor RT and the transformer TR may be replaced with a transformer having a special winding structure having a leak reactance sufficient to substitute the function of the reactor.
  • the leg LGr includes a current detector (not shown) that detects a positive arm current (not shown, R-phase positive current Ipr) flowing from the connection point CP to the terminal P, and a negative current flowing from the terminal N to the connection point CP.
  • a current detector (not shown) for detecting the side arm current (illustrated, R-phase negative side current Inr) may be provided.
  • FIG. 3 is a diagram showing an example of the configuration of the cell CL.
  • the cell CL is, for example, a half bridge circuit.
  • the cell CL includes, for example, a plurality of switching elements Q (illustrated switching elements Q1 to Q2), a number of diodes D (illustrated diodes D1 to D2) corresponding to the switching elements Q, and capacitors.
  • the switching element Q is, for example, an Insulated Gate Bipolar Transistor (IGBT).
  • IGBT Insulated Gate Bipolar Transistor
  • the switching element Q is not limited to the IGBT.
  • the switching element Q may be any element as long as it is a self-turn-off switching element that can realize a converter or an inverter. In this embodiment, a case where the switching element Q is an IGBT will be described.
  • the switching element Q1 and the switching element Q2 are connected in series with each other.
  • the switching element Q1, the switching element Q2, and the capacitor C are connected in parallel with each other.
  • Each switching element Q and the diode D are connected in parallel with each other. Specifically, the switching element Q1 and the diode D1 are connected in parallel with each other, and the switching element Q2 and the diode D2 are connected in parallel with each other.
  • the cell CL includes a positive electrode terminal connected to the terminal P side of the leg LG and a negative electrode terminal connected to the terminal N side.
  • the positive terminal of the cell CL is connected to the connection point between the switching element Q1 and the switching element Q2, and the negative terminal of the cell CL is connected to the emitter terminal of the switching element Q2.
  • the voltage generated between the positive electrode terminal and the negative electrode terminal of the cell CL will be referred to as the cell voltage Vcl.
  • Each switching element Q has a switching terminal (not shown) for switching the switching element Q on and off, and the switching terminal is connected to the converter control device 20 and a control signal is input.
  • the switching element Q1 receives the first gate signal gtp as a control signal
  • the switching element Q2 receives the second gate signal gtn as a control signal.
  • the capacitors C included in the cells CL are charged or discharged by switching each switching element Q on or off based on the control signal.
  • the cell CL is provided with a voltage detector (not shown) that detects the capacitor voltage Vc which is the voltage of the capacitor C.
  • the converter control device 20 includes a control unit 200 and a gate signal generation unit 300.
  • the control unit 200 for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software) stored in a storage unit (not shown), the AC information calculation unit 210 and the voltage command value calculation.
  • the unit 220, the carrier frequency switching command unit 230, the carrier frequency switching unit 240, and the triangular wave carrier generation unit 250 are realized as functional units. Some or all of these components are hardware (circuits) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit). Part; including circuitry), or may be realized by cooperation of software and hardware.
  • LSI Large Scale Integration
  • ASIC Application Specific Integrated Circuit
  • FPGA Field-Programmable Gate Array
  • GPU Graphics Processing Unit
  • the AC information calculation unit 210 calculates the voltages (R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt shown) detected by a device (detector CS shown) that detects the voltage of each phase of the AC system.
  • the information shown is acquired, and the AC system effective voltage Vd and the AC system reactive voltage Vq are calculated based on the acquired information.
  • the AC information calculation unit 210 repeats the calculation as a calculation for following and synchronizing with the AC system voltage so that the calculated value of the AC system reactive voltage Vq becomes zero. Thereby, the AC information calculation unit 210 calculates the AC frequency fpll and the AC system voltage phase theta.
  • the AC frequency fpll is the frequency of the AC system voltage with which the power converter 10 is interconnected.
  • the AC system voltage phase theta is a value indicating the phase of a reference phase having the AC voltage. Details of the processing of the AC information calculation unit 210 will be described later.
  • the voltage command value calculator 220 calculates each state of the power converter 10 (for example, the positive side currents Ipr to Ipt, the negative side currents Inr to Int, and each capacitor voltage Vc) and the AC information calculator 210. Based on the AC system active voltage Vd, the AC system reactive voltage Vq, and the AC system voltage phase theta, the active power PE output by the power converter 10 and the reactive power QE have a predetermined active power command value PE *. Then, the cell voltage command value Vcl * for instructing the cell voltage Vcl of each cell CL is calculated so that the reactive power command value QE * is obtained.
  • the carrier frequency switching command unit 230 is a signal that commands the frequency of the triangular wave carrier signal based on the AC system effective voltage Vd calculated by the AC information calculation unit 210 and a command from the external system (external command SYS shown).
  • the first pulse switching command SW1 and the second pulse switching command SW2 shown in the figure are output to the carrier frequency switching unit 240.
  • the triangular wave carrier signal is a signal used when the switching control signal of the switching element Q is generated by the triangular wave comparison method. In the triangular wave comparison method, the frequency of the triangular wave carrier signal and the switching frequency match. In the following description, the frequency of the triangular wave carrier signal is also referred to as the switching frequency.
  • the external system is, for example, a protection device for the power conversion device 1. Details of the processing of the carrier frequency switching command unit 230 will be described later.
  • the carrier frequency switching unit 240 based on the AC frequency fpll calculated by the AC information calculation unit 210, the first pulse switching command SW1 and the second pulse switching command SW2 output by the carrier frequency switching command unit 230, A command value (hereinafter, carrier command frequency fc *) that indicates the switching frequency of the power converter 10 is selected and output to the triangular wave carrier generation unit 250. Details of the processing of the carrier frequency switching unit 240 will be described later.
  • the triangular wave carrier generation unit 250 generates a triangular wave carrier signal Tri * for each cell CL based on the carrier command frequency fc * output by the carrier frequency switching unit 240.
  • This triangular wave carrier signal Tri * is a signal in which the phase is uniformly shifted for each cell CL in order from one end to the other end of the cells CL connected in series to the arm unit.
  • phase shift order of the triangular wave carrier signal Tri * does not necessarily have to match the serial connection order of the cells CL, as long as they are evenly phase-shifted between arbitrary cells CL belonging to the same arm unit. . Therefore, the phase shift order of the triangular wave carrier signal Tri * can be arbitrarily changed.
  • the case where the phase shift order of the triangular wave carrier signal Tri * is the series connection order of the cells CL will be described as an example.
  • the gate signal generation unit 300 is based on the cell voltage command value Vcl * of each cell CL calculated by the voltage command value calculation unit 220 and the triangular wave carrier signal Tri * for each cell CL generated by the triangular wave carrier generation unit 250. Then, the first gate signal gtp and the second gate signal gtn for each cell CL are generated and output to the power converter 10. Details of the triangular wave carrier signal Tri * generated by the triangular wave carrier generation unit 250, the first gate signal gtp, and the second gate signal gtn will be described later.
  • FIG. 4 is a diagram conceptually illustrating an example of processing of the AC information calculation unit 210 of the embodiment.
  • the AC information calculation unit 210 includes a conversion unit 211, a PI calculation unit 212, an addition unit 213, and an oscillator 214 as functional units.
  • the conversion unit 211 acquires information indicating the voltages (R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt shown) detected by the detector CS.
  • the conversion unit 211 converts (calculates) the acquired R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt into an AC system effective voltage Vd and an AC system reactive voltage Vq, using Equation (1).
  • the AC system voltage phase theta is a value output by an oscillator 214 described later, and is a value indicating the voltage phase of a certain reference phase (R phase in this example) of the AC system.
  • the PI calculation unit 212 based on the AC system reactive voltage Vq converted by the conversion unit 211, the frequency difference between the frequency of the AC system voltage with which the power converter 10 is interconnected and the reference AC system frequency fs0 (hereinafter, referred to as frequency).
  • the difference ⁇ fpll) is calculated.
  • the frequency difference ⁇ fpll takes a positive value when the frequency of the AC system voltage is higher than the reference AC system frequency fs0, and takes a negative value when it is lower than the reference AC system frequency fs0.
  • the reference AC system frequency fs0 is a rated frequency of the interconnected AC system, and is, for example, a constant of 50 [Hz] or 60 [Hz].
  • the frequency difference ⁇ fpll continues to increase or decrease until the calculated value of the AC system reactive voltage Vq input to the PI calculation unit 212 becomes zero, and is the value of the difference between the actual AC system frequency and the reference AC system frequency fs0. Converge to.
  • the adder 213 adds the frequency difference ⁇ fpll calculated by the PI calculator 212 to the reference AC system frequency fs0.
  • the frequency obtained by adding the frequency difference ⁇ fpll to the reference AC system frequency fs0 is referred to as AC frequency fpll.
  • the oscillator 214 outputs an AC system voltage phase theta that monotonically increases from the minimum value 0 to the maximum value 2 ⁇ according to the frequency of the AC frequency fpll calculated by the adding unit 213.
  • the AC system voltage phase theta is used for converting the AC system effective voltage Vd and the AC system reactive voltage Vq of the conversion unit 211 and for generating the cell voltage command value Vcl *.
  • the AC information calculation unit 210 repeats the calculation of the AC system voltage phase theta so that the calculated value of the AC system reactive voltage Vq in the conversion unit 211 becomes zero, and thus the AC system synchronized with the AC system voltage.
  • the frequency fpll and the AC system voltage phase theta are obtained.
  • the switching frequency of the switching element Q may be controlled so as to be proportional to the AC frequency fpll.
  • the calculated value fpll of the AC frequency also fluctuates, and the switching frequency of the switching element Q falls outside the normal range. Beyond that, there is a risk that the power conversion device 1 may not operate stably.
  • the PI calculation unit 212 sets the frequency difference ⁇ fpll to the + limit value ⁇ fpll_limit when the frequency difference ⁇ fpll is larger than the limit value (hereinafter, the limit value ⁇ fpll_limit), and sets the frequency difference ⁇ fpll_limit to the ⁇ limit value ⁇ fpll_limit.
  • ⁇ fpll may be output as ⁇ limit value ⁇ fpll_limit.
  • the addition unit 213 can limit the AC frequency fpll to a frequency in the range of the reference AC system frequency fs0 + the limit value ⁇ fpll_limit to the reference AC system frequency fs0 ⁇ the limit value ⁇ fpll_limit.
  • the limit value ⁇ fpll_limit is, for example, a positive value smaller than the reference AC system frequency fs0.
  • FIG. 5 is a figure which shows notionally an example of a process of the carrier frequency switching instruction
  • the carrier frequency switching command unit 230 includes a first comparator 231, a determination unit 232, a first pulse output unit 233, and a second pulse output unit 234 as functional units.
  • the first comparator 231 compares the absolute value of the AC system effective voltage Vd calculated by the AC information calculation unit 210 with the voltage upper limit value Vth_H and the voltage lower limit value Vth_L.
  • the first comparator 231 outputs the system voltage abnormality signal ERR when the absolute value of the AC system effective voltage Vd is larger than the voltage upper limit value Vth_H or when the absolute value of the AC system effective voltage Vd is smaller than the voltage lower limit value Vth_L. Output.
  • the absolute value of the AC system effective voltage Vd is larger than the voltage upper limit value Vth_H, or the absolute value of the AC system effective voltage Vd is smaller than the voltage lower limit value Vth_L, a system fault occurs in the AC system and the AC system This is a state in which the amplitude of each phase voltage shows an abnormal value or the phases are unbalanced.
  • the range indicated by the voltage upper limit value Vth_H to the voltage lower limit value Vth_L is an example of a “predetermined range” that the absolute value of the AC system effective voltage Vd can take.
  • the first comparator 231 compares the combined voltage vector Vdq obtained by the equation (2) with a predetermined threshold value, and the value of the combined voltage vector Vdq is greater than a predetermined upper threshold value or less than a predetermined lower threshold value. If it is smaller, the system voltage abnormality signal ERR may be output.
  • the determination unit 232 determines whether or not the system voltage abnormality signal ERR has been output by the first comparator 231 or whether the external command SYS has been output by the external system.
  • the determination unit 232 outputs the system voltage abnormality signal ERR to the first pulse output unit 233 when either the system voltage abnormality signal ERR or the external command SYS is output.
  • the first pulse output unit 233 When the determination unit 232 outputs the system voltage abnormality signal ERR, the first pulse output unit 233 outputs the first pulse switching command SW1 only for the first period TM1 after the system voltage abnormality signal ERR is output. Further, the first pulse output unit 233 outputs the first pulse switching command SW1 when the external command SYS is output even when the first comparator 231 does not detect a system fault.
  • the second pulse output unit 234 When the system voltage abnormality signal ERR is output by the first comparator 231, the second pulse output unit 234 outputs the second pulse switching command SW2 only for the second period TM2 after the system voltage abnormality signal ERR is output. To do.
  • FIG. 6 is a diagram conceptually illustrating an example of processing of the carrier frequency switching unit 240 of the embodiment.
  • the carrier frequency switching unit 240 includes a first switching unit 241, a multiplication unit 242, and a second switching unit 243 as functional units.
  • the first switching unit 241 switches the non-integer value output to the multiplication unit 242 to either one of the first non-integer value N1 and the second non-integer value N2.
  • the first switching unit 241 outputs the first non-integer value N1 to the multiplication unit 242 when the first pulse switching command SW1 is not output, and the second non-integer value N1 when the first pulse switching command SW1 is output.
  • the integer value N2 is output.
  • the first non-integer value N1 and the second non-integer value N2 are positive values that are not integers.
  • the first non-integer value N1 is a value smaller than the second non-integer value N2.
  • the multiplying unit 242 multiplies the AC frequency fpll by the non-integer value output by the first switching unit 241.
  • the frequency obtained by multiplying the AC frequency fpll by the first non-integer value N1 is referred to as the first frequency fc1
  • the frequency obtained by multiplying the AC frequency fpll by the second non-integer value N2 is referred to as the first frequency fc1. It is described as 2 frequencies fc2.
  • the second switching unit 243 sets the frequency output to the triangular wave carrier generation unit 250 as the carrier command frequency fc * to the frequency output by the multiplication unit 242 (first frequency fc1 or second frequency fc2) and the third frequency fc3. And switch to either one of.
  • the second switching unit 243 outputs the first frequency fc1 or the second frequency fc2 output by the multiplication unit 242 as the carrier command frequency fc *, and the second pulse
  • the third frequency fc3 is output as the carrier command frequency fc *.
  • the third frequency fc3 is a predetermined frequency.
  • FIG. 7 is a graph showing an example of the relationship between the first frequency fc1, the second frequency fc2, the third frequency fc3, and the first period TM1 and the second period TM2.
  • the horizontal axis of FIG. 7 shows the carrier command frequency fc *, and the vertical axis shows the time (hereinafter, continuous control time) that can be continuously controlled by the switching frequency of the carrier command frequency fc *.
  • W1 is a waveform showing the relationship between the carrier command frequency fc * and the continuous control time.
  • the carrier command frequency fc * increases, the amount of heat generation per unit time (that is, power conversion loss) occurs, and the larger the power conversion loss, the shorter the continuous control time. Therefore, when the allowable heat generation amount due to the power conversion loss is fixed, the relationship between the carrier command frequency fc * and the continuous control time is approximately inversely proportional as shown by the waveform W1.
  • the power converter 10 when the carrier command frequency fc * takes a value that is an integer multiple of the AC frequency fpll or a value close to an integer multiple in the low frequency region of the constant K ⁇ AC frequency fpll or less, the power converter 10 causes the capacitor voltage Vc It becomes difficult to maintain the balance. On the other hand, even if the carrier command frequency fc * takes an integer multiple of the AC frequency fpll or a value close to an integer multiple in a high frequency region higher than the constant K ⁇ AC frequency fpll, the power converter 10 uses the capacitor. The balance of the voltage Vc can be maintained.
  • the constant K is, for example, a value of “4” or more, and the first non-integer value N1 and the second non-integer value N2 are values less than the constant K. That is, the first non-integer value N1 and the second non-integer value N2 are, for example, non-integer values of about “2” to “4” (for example, 2.1 to 2.9 and 3.1 to 3.9). ).
  • the first frequency fc1 and the second frequency fc2 are frequencies in a low frequency region equal to or less than a constant K ⁇ AC frequency fpll, but the AC frequency fpll is multiplied by a first non-integer value N1 or a second non-integer value N2. Frequency. Therefore, the power converter 10 can maintain the balance of the capacitor voltage Vc even if switching control is performed by the switching frequency of the carrier command frequency fc * of the first frequency fc1 or the second frequency fc2.
  • the difference between the second non-integer value N2 and the first non-integer value N1 is made sufficiently small.
  • the third frequency fc3 is a frequency higher than the first frequency fc1 and the second frequency fc2, and is a frequency in a high frequency range equal to or higher than the constant K ⁇ AC frequency fpll.
  • the third frequency fc3 may be an integral multiple of the AC frequency fpll or a non-integer multiple of the AC frequency fpll.
  • the third frequency fc3 is a predetermined frequency (that is, a fixed value) has been described.
  • a value obtained by multiplying the AC frequency fpll by an integer equal to or greater than a constant K or a non-integer equal to or greater than the constant K May be
  • the carrier frequency switching unit 240 has the third frequency fc3 during the second period TM2 in which the second pulse switching command SW2 is output (that is, during the time period during which the system fault continues). Is output as the carrier command frequency fc *.
  • the third frequency fc3 is a frequency in a high frequency range, and thus has a large power loss per unit time. Therefore, it is difficult for the power converter 10 to continue operating for a long period of time. Therefore, the carrier frequency switching unit 240 outputs the third frequency fc3 for a short period (in this example, the second period TM2).
  • the second period TM2 is, for example, a period until the AC circuit breaker provided in the AC system disconnects the fault circuit and the fault is eliminated.
  • the second period TM2 may be set based on a past accident case or a predetermined recovery time, and is, for example, a period of several times the AC system voltage cycle.
  • the second period TM2 may be a period during which heat generated by switching control at the third frequency fc3 can be cooled according to the cooling function of the power converter 10.
  • the carrier frequency switching unit 240 outputs the second pulse switching command SW2 and does not output the first pulse switching command SW1 (that is, the second period TM2 after the occurrence of the system fault).
  • the second frequency fc2 is output as the carrier command frequency fc * during the first period TM1 to the second period TM2 after the lapse of time or during the first period TM1 after receiving the external command SYS).
  • the second frequency fc2 is a frequency in the lower frequency range than the third frequency fc3
  • the power loss per unit time is smaller than that of the third frequency fc3. Therefore, the power converter 10 can continue to operate the power converter 10 for a longer period than the third frequency fc3. Therefore, the first period TM1 is longer than the second period TM2.
  • the carrier frequency switching unit 240 sets the first frequency fc1 to the carrier command frequency when the first pulse switching command SW1 and the second pulse switching command SW2 are not output (that is, in the normal state). Output as fc *.
  • the power converter 10 has a cooling function that allows constant switching control with the first frequency fc1.
  • FIG. 8 is a graph showing an example of various signals generated by the converter control device 20.
  • a waveform W11 indicates a j-th (j is a natural number) cell CL (hereinafter, cell CL (j)) of the cell CL connected in series to a certain arm unit of the power converter 10. It is a waveform showing the change over time of the triangular wave carrier signal Tri (j) * used for generating the 1-gate signal gtp (j).
  • the waveform W12 is a waveform showing a change over time of the cell voltage command value Vcl * which is a command value of the voltage generated between the positive electrode terminal and the negative electrode terminal of the cell CL (j).
  • the waveform W13 is the triangular wave carrier signal Tri (j + 1) used to generate the first gate signal gtp (j + 1) of the cell CL (hereinafter, cell CL (j + 1)) connected in series adjacent to the cell CL (j). It is a waveform showing the change with time of *.
  • a waveform W14 is a waveform showing a temporal change of a cell voltage command value Vcl (j + 1) *, which is a command value of a voltage generated between the positive electrode terminal and the negative electrode terminal of the cell CL (j + 1).
  • the waveform W15 is a waveform showing the change over time of the first gate signal gtp (j).
  • the waveform W16 is a waveform showing the change over time of the first gate signal gtp (j + 1).
  • the triangular wave carrier signal Tri (j) * and the triangular wave carrier signal Tri (j + 1) * are triangular wave waveforms having a cycle of 1 / carrier command frequency fc *.
  • the triangular wave carrier signal Tri (j) * is made dimensionless so that the maximum value thereof coincides with the capacitor voltage Vc of the cell CL, and is shown by the range of 0 to 1.
  • the cell voltage command value Vcl (j) * and the cell voltage command value Vcl (j + 1) * are substantially equal.
  • the cell voltage command value Vcl (j) * is made dimensionless with the capacitor voltage Vc of the cell CL as a reference, and is represented by a range of 0 to 1, like the triangular wave carrier signal Tri *.
  • the gate signal generation unit 300 generates the first gate signal gtp and the second gate signal gtn by phase shift PWM (Pulse Width Modulation). As shown by the waveforms W11 and W13, when the number of cells CL for each arm unit is n, the gate signal generator 300 sets the phases of the triangular wave carrier signals Tri * assigned to the cells CL of the arm units to 2 ⁇ / n. Shift one by one. n is the number of cells CL (n [pieces] in this example) connected in series to the arm unit.
  • PWM Pulse Width Modulation
  • the triangular wave carrier signal Tri (j) * and the triangular wave carrier signal Tri (j + 1) * of the cell CL (j) and the cell CL (j + 1) adjacent in phase have a time of 1 / (n ⁇ fc *). Just a gap occurs.
  • the gate signal generation unit 300 compares the triangular wave carrier signal Tri (j) * with the cell voltage command value Vcl (j) *, and when Vcl (j) * ⁇ Tri (j) *, the first gate signal gtp. (J) is changed to “0” (that is, the switching element Q1 of the cell CL (j) is turned off), and when Vcl (j) *> Tri (j) *, the first gate signal gtp (j) is changed. It is changed to "1" (that is, the switching element Q1 of the cell CL (j) is turned on).
  • the gate signal generation unit 300 compares the triangular wave carrier signal Tri (j + 1) * with the cell voltage command value Vcl (j + 1) * to change the first gate signal gtp (j + 1).
  • the second gate signal gtn of the switching element Q2 is a logical inversion signal of the first gate signal gtp.
  • the power converter 10 determines the change timing of the first gate signal gtp of each cell CL in the arm unit. Is shifted to generate a multi-level voltage of maximum n levels as a combined voltage of the arm unit.
  • FIG. 9 is a figure which shows an example of operation
  • Waveforms W21 to W23 are waveforms showing changes with time of the AC voltage of each phase of the AC system.
  • the waveform W24 is a waveform showing a change with time of the AC system effective voltage Vd.
  • the waveform W25 is a waveform showing the change over time of the first pulse switching command SW1.
  • the waveform W26 is a waveform showing the change over time of the second pulse switching command SW2.
  • the waveform W27 is a waveform showing the change over time of the carrier command frequency fc *.
  • the waveform W28 is a waveform showing the maximum value of the capacitor voltage Vc.
  • the waveform W29 is a waveform showing the minimum value of the capacitor voltage Vc.
  • the carrier frequency switching unit 240 outputs the first frequency fc1 as the carrier command frequency fc * in the normal state.
  • the voltage of a certain phase (in this example, the R phase) of the AC voltage of each phase of the AC system indicated by the waveforms W21 to W23 is almost 0 [. V].
  • the R phase and the other two healthy phases (S phase and T phase in this example) are unbalanced.
  • the AC system effective voltage Vd oscillates at a frequency approximately twice the reference AC system frequency fs0, and falls below the voltage lower limit value Vth_L.
  • the carrier frequency switching command unit 230 When the AC system effective voltage Vd falls below the voltage lower limit value Vth_L, the carrier frequency switching command unit 230 outputs the first pulse switching command SW1 only for the first period TM1 and the second pulse switching command only for the second period TM2. Output SW2.
  • the carrier frequency switching unit 240 outputs the third frequency fc3 as the carrier command frequency fc * while the second pulse switching command SW2 is being output (that is, the second period TM2).
  • the disturbance immediately after the occurrence of the accident increases the variation in the capacitor voltage Vc in the arm unit (the difference generated between the waveform W28 and the waveform W29).
  • the capacitor voltage Vc converges quickly without increasing the variation. Can be made.
  • the capacitor voltage Vc may reach the overvoltage level and the operation of the power converter 10 may stop. In this case, the power converter 10 cannot restart the operation until the capacitor C is discharged and the capacitor voltage Vc returns to the normal level. According to the above-described processing, the power converter 10 performs the switching control with the third frequency fc3 for a short period (second period TM2), so that the operation continuity is improved without increasing the capacitor voltage Vc. You can
  • the AC system effective voltage Vd may temporarily exceed the voltage upper limit value Vth_H.
  • the second pulse switching command SW2 is stopped around time t1, and the carrier frequency switching unit 240 outputs only the first pulse switching command SW1.
  • the period during which only the first pulse switching command SW1 is output is from time t1 to time t2 (that is, between the first period TM1 and the second period TM2).
  • the carrier frequency switching unit 240 outputs the carrier command frequency fc * while the first pulse switching command SW1 is being output (that is, during the second period TM2 to the first period TM1 after the end of the second period TM2). And outputs the second frequency fc2.
  • the power converter 10 uses the second frequency fc2. Is controlled by the first gate signal gtp and the second gate signal gtn, which have a higher time resolution than in the normal state based on the triangular wave carrier signal Tri *, and converge quickly without increasing the variation in the capacitor voltage Vc. Can be made.
  • the power converter 10 performs the switching control with the second frequency fc2 only for a short period (first period TM1), so that the operation continuity is improved without increasing the capacitor voltage Vc.
  • the power converter 10 can be stably operated by the carrier command frequency fc * in the low frequency range without lowering the power conversion efficiency and maintaining the balance of the capacitor voltage Vc. .
  • the carrier frequency switching command unit 230 causes the first pulse switching command SW1, immediately after the time t0. Since the second pulse switching command SW2 has already been output, the first pulse switching command SW1 and the second pulse switching command SW2 are not output again at this timing. However, when the AC system effective voltage Vd does not fall below the voltage lower limit value Vth_L at time t0, the carrier frequency switching command unit 230, at this timing, the first pulse switching command SW1 and the second pulse switching command SW2. May be output.
  • FIG. 10 and 11 are flowcharts (No. 1) to (No. 2) showing an example of the operation of the power conversion device 1 of the embodiment.
  • the flowchart shown in FIG. 10 and the flowchart shown in FIG. 11 are executed simultaneously in parallel.
  • the conversion unit 211 acquires information indicating the voltage (R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt) of each phase of the AC system from the detector CS (step S100).
  • the conversion unit 211 converts the AC system valid voltage Vd and the AC system reactive voltage Vq based on the acquired voltage of each phase of the AC system (step S102).
  • the addition unit 213 adds the reference AC system frequency fs0 to the frequency difference ⁇ fpll calculated by the PI calculation unit 212 based on the AC system reactive voltage Vq to calculate the AC frequency fpll (step S104). Further, the oscillator 214 outputs an AC system voltage phase theta that monotonically increases from the minimum value 0 to the maximum value 2 ⁇ according to the frequency of the AC frequency fpll calculated by the adding unit 213 (step S106).
  • the first comparator 231 compares the absolute value of the AC system effective voltage Vd converted by the conversion unit 211 with the voltage upper limit value Vth_H and the voltage lower limit value Vth_L, and the absolute value of the AC system effective voltage Vd is the voltage. It is compared whether it is within a predetermined range from the upper limit value Vth_H to the voltage lower limit value Vth_L (step S108). When the comparison result of the first comparator 231 indicates that the absolute value of the AC system effective voltage Vd is within the predetermined range, the determination unit 232 determines whether or not the external command SYS is received from the external system (step S110). The determination unit 232 ends the process when the external command SYS is not received from the external system. When the determination result of the determination unit 232 indicates that the external command SYS is received, the first pulse output unit 233 outputs the first pulse switching command SW1 and advances the process to step S116.
  • the first comparator 231 If the absolute value of the AC system effective voltage Vd is outside the predetermined range, the first comparator 231 outputs the system voltage abnormality signal ERR (step S114).
  • the first pulse output unit 233 outputs the first pulse switching command SW1 along with the output of the system voltage abnormality signal ERR, and the second pulse output unit 234 outputs the system voltage abnormality signal ERR. Accordingly, the second pulse switching command SW2 is output (step S114). Note that, in step S114, the timings at which the first pulse switching command SW1 and the second pulse switching command SW2 are output match.
  • the second pulse output unit 234 continues to output the second pulse switching command SW2 from the time the second pulse switching command SW2 is output until the second period TM2 elapses (step S116).
  • the second pulse output unit 234 stops the second pulse switching command SW2 after the second period TM2 has elapsed after outputting the second pulse switching command SW2 (step S118).
  • the first pulse output unit 233 continues to output the first pulse switching command SW1 until the first period TM1 elapses after outputting the first pulse switching command SW1 (step S120).
  • the first pulse output unit 233 stops the first pulse switching command SW1 after the first period TM1 has elapsed after outputting the first pulse switching command SW1 (step S122).
  • the carrier frequency switching unit 240 determines whether or not the second pulse switching command SW2 is output (step S200). When the second pulse switching command SW2 is output, the carrier frequency switching unit 240 outputs the third frequency fc3 as the carrier command frequency fc * (step S202). When the second pulse switching command SW2 is not output, the carrier frequency switching unit 240 determines whether the first pulse switching command SW1 is output (step S204). Furthermore, when the first pulse switching command SW1 is output, the carrier frequency switching unit 240 outputs the second frequency fc2 as the carrier command frequency fc * (step S206). When the first pulse switching command SW1 and the second pulse switching command SW2 are not output, the carrier frequency switching unit 240 outputs the first frequency fc1 as the carrier command frequency fc * (step S208).
  • the triangular wave carrier generation unit 250 generates the triangular wave carrier signal Tri * for each cell CL based on the carrier command frequency fc * output from the carrier frequency switching unit 240 (step S210).
  • the voltage command value calculation unit 220 based on the AC system effective voltage Vd, the AC system reactive voltage Vq, the AC system voltage phase theta, and the like calculated by the AC information calculation unit 210, the cell voltage command value Vcl * for each cell CL. Is generated (step S212).
  • the gate signal generation unit 300 based on the triangular wave carrier signal Tri * generated by the triangular wave carrier generation unit 250 and the cell voltage command value Vcl * generated by the voltage command value calculation unit 220, the first for each cell CL.
  • the gate signal gtp and the second gate signal gtn are generated (step S214).
  • the power converter 10 performs switching control of the switching element Q based on the first gate signal gtp and the second gate signal gtn generated by the gate signal generation unit 300, and converts power.
  • the power conversion device 1 of the present embodiment controls the power converter 10 by the carrier command frequency fc * in the low frequency range in the normal time, thereby reducing the power conversion loss and reducing the capacitor voltage. It is possible to prevent the balance of Vc from being lost.
  • the power conversion device 1 of the present embodiment controls the power converter 10 for a short period of time by the carrier command frequency fc * in the high frequency range at the time of a system fault, so that the total heat generation amount that is the integrated value of the power conversion loss. It is possible to prevent the capacitor voltage Vc from reaching the overvoltage level while suppressing an increase in the voltage. Therefore, the power conversion device 1 of the present embodiment can improve the operation continuity at the time of a system fault while reducing the power loss related to the power conversion.
  • the power conversion device 1 of the present embodiment controls the power converter 10 by using the carrier command frequency fc * in different high frequency regions at the timing when the system fault occurs and the timing when the system fault converges to some extent. As a result, it is possible to further suppress an increase in the total heat generation amount, which is the integrated value of the power conversion loss. Further, the power conversion device 1 of the present embodiment controls the power converter 10 by the carrier command frequency fc * so as to finish in a shorter period as the carrier command frequency fc * is in a higher frequency range. It is possible to further suppress an increase in the total heat generation amount that is the integrated value of the power conversion loss. Furthermore, by controlling the power converter 10 using the carrier command frequency fc * having the highest frequency at the timing when the system fault has the greatest influence on the operation continuity, the operation continuity can be further improved. .
  • the power conversion device 1 of the present embodiment controls the power converter 10 by the carrier command frequency fc * in the high frequency range based on the external command SYS received from the external system.
  • the power conversion device 1 according to the present embodiment can quickly perform power conversion when the external protection device or the like of the power conversion device 1 precedes the power conversion device 1 or independently detects an abnormality such as a system accident.
  • the power converter 10 can be controlled so that the converter 1 can continue operation.
  • the power conversion device 1 of the present embodiment suppresses an increase in power conversion loss and reduces the cooling function of the power converter 10 as described above, thereby reducing the power conversion device 1 cost and size. Can be converted.
  • the carrier frequency switching command unit 230a of the first modification will be described.
  • the case where the carrier frequency switching command unit 230 outputs the first pulse switching command SW1 and the second pulse switching command SW2 based on the system voltage abnormality signal ERR and the external command SYS has been described.
  • the carrier frequency switching command unit 230a of Modification Example 1 further, based on the number of times (hereinafter, the number of counts ct) that the AC system effective voltage Vd deviates from the range indicated by the voltage upper limit value Vth_H and the voltage lower limit value Vth_L, A case where the first pulse switching command SW1 and the second pulse switching command SW2 are output will be described.
  • the same components as those of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.
  • FIG. 12 is a diagram conceptually showing the process of the carrier frequency switching command unit 230a of the first modification.
  • the carrier frequency switching command unit 230a of the first modification is replaced with (or in addition to) the functional units included in the carrier frequency switching command unit 230, and the first comparator 231, the determination unit 232a, and the first pulse output unit.
  • 233, a second pulse output unit 234, a number counter 235, a second comparator 236, and a third comparator 237 are provided as functional units.
  • the frequency counter 235 sets a certain set time based on the information indicating that the comparison result of the first comparator 231 indicates that the AC system effective voltage Vd exceeds the voltage upper limit value Vth_H or falls below the voltage lower limit value Vth_L.
  • the number of abnormalities in the system voltage within 10 seconds (for example, 10 seconds) is counted, and the counted number ct is output to the second comparator 236 and the third comparator 237.
  • the frequency counter 235 repeatedly measures the voltage upper limit value during another set time (for example, 1 [second]) that is sufficiently shorter than the set time of the count target because the AC system effective voltage Vd vibrates finely.
  • Vth_H deviates from the range indicated by the voltage lower limit value Vth_L or returns to the range, they are collectively counted as one system voltage abnormal state.
  • the second comparator 236 compares the count number ct output by the number counter 235 with the switching number first upper limit value SW_lim1.
  • the second comparator 236 outputs a "False” signal when the count number ct does not exceed the switching number first upper limit value SW_lim1, and when the count number ct exceeds the switching number first upper limit value SW_lim1, " True ”signal.
  • the third comparator 237 compares the count number ct output by the number counter 235 with the switching number second upper limit value SW_lim2.
  • the third comparator 237 outputs a "False” signal when the count number ct does not exceed the switching number second upper limit value SW_lim2, and when the count number ct exceeds the switching number second upper limit value SW_lim2, " True ”signal.
  • the determination unit 232a determines whether the first comparator 231 outputs the system voltage abnormality signal ERR and the second comparator 236 outputs the “False” signal.
  • the first pulse output unit 233 outputs the system voltage abnormality signal ERR and the “False” signal by the determination unit 232a (that is, the count number ct does not exceed the switching number first upper limit value SW_lim1). , And outputs the first pulse switching command SW1 only during the first period TM1.
  • the first pulse output unit 233 of the modified example 1 outputs the “True” signal by the second comparator 236 even when the system voltage abnormality signal ERR is output (that is, the count).
  • the switching count first upper limit value SW_lim1 is a value indicating the number of times the power converter 10 can be controlled by the second frequency fc2.
  • the determination unit 232a determines whether or not the system voltage abnormality signal ERR is output by the first comparator 231 and the “False” signal is output from the third comparator 237.
  • the second pulse output unit 234 outputs the system voltage abnormality signal ERR and the “False” signal by the determination unit 232a (that is, the count number ct does not exceed the switching number second upper limit SW_lim2). , And outputs the second pulse switching command SW2 only during the second period TM2.
  • the second pulse output unit 234 of the modified example 1 outputs the “True” signal by the third comparator 237 even when the system voltage abnormality signal ERR is output (that is, the count).
  • the switching count second upper limit value SW_lim2 is a value indicating the number of times the power converter 10 can be controlled by the third frequency fc3.
  • the switching count first upper limit value SW_lim1 and the switching count second upper limit value SW_lim2 may be the same value or different values. Further, the switching number first upper limit value SW_lim1 and the switching number second upper limit value SW_lim2 may be indicated by time (period) instead of (or in addition to) the number of times. In this case, the upper limit value is a value indicating a time (period) during which the power converter 10 can be controlled by the second frequency fc2 or the third frequency fc3.
  • the switching number first upper limit value SW_lim1 is an example of the “second predetermined number”
  • the switching number second upper limit value SW_lim2 is an example of the “first predetermined number”.
  • the carrier frequency switching unit 240 determines that the absolute value of the AC system effective voltage Vd falls within the predetermined range. Even if it exceeds, the first frequency fc1 is selected as the carrier command frequency fc *.
  • the switching number first upper limit value SW_lim1 or the switching number third upper limit SW_lim3 is an example of the “third predetermined number”.
  • the power conversion device 1 of the first modification increases the total heat generation amount due to the power conversion loss by limiting the number of effective times of the first pulse switching command SW1 and the second pulse switching command SW2. It is possible to prevent the power converter 1 from stopping for a long time due to a failure due to heat generation.
  • the power conversion device 1 of the first modification when a system fault of the system connected to the power conversion device 1 or a system fault of the system notified by the external command SYS from the external system frequently occurs in a short time. Even in this case, it is possible to reduce the power loss related to the power conversion and improve the operation continuity at the time of a system fault within the range in which the total calorific value does not exceed the allowable value.
  • FIG. 13 is a diagram conceptually showing the process of the carrier frequency switching command unit 230b of the second modification.
  • the carrier frequency switching command unit 230b of Modification 2 further includes a fourth comparator 238 in addition to the functional units included in the carrier frequency switching command unit 230b.
  • the fourth comparator 238 compares the count number ct output by the number counter 235 with the switching number third upper limit SW_lim3.
  • the fourth comparator 238 outputs the stop command signal STP to the gate signal generation unit 300 when the count number ct exceeds the switching number third upper limit SW_lim3.
  • the switching number third upper limit SW_lim3 is a value sufficiently larger than the switching number first upper limit value SW_lim1 and the switching number second upper limit value SW_lim2. Further, the switching upper limit third upper limit SW_lim3 may be indicated by time (period) instead of (or in addition to) the number of times. In this case, the upper limit value is a value indicating a time (period) during which the power converter 10 can be controlled by the carrier command frequency fc * (for example, the second frequency fc2 or the third frequency fc3) in the high frequency range.
  • the switching count third upper limit SW_lim3 is an example of a “fourth predetermined count”.
  • the voltage command value calculation unit 220 determines that the active power PE output by the power converter 10 and the reactive power QE have a predetermined active power command value PE * and reactive power. The case has been described in which the cell voltage command value Vcl * for instructing the cell voltage Vcl of each cell CL is calculated so as to be the command value QE *. In the converter control device 20a according to the modification 3, the voltage command value calculation unit 220 sets limits on the active power command value PE * and the reactive power command value QE * based on the presence / absence of the first pulse switching command SW1. The case will be described. In addition, about the structure similar to embodiment and the modification mentioned above, the same code
  • FIG. 14 is a diagram illustrating an example of the configuration of the converter control device 20a according to the third modification.
  • the converter control device 20a according to the modification 3 has a voltage command value calculation unit 220, a carrier frequency switching command unit 230, and a carrier frequency switching unit 240.
  • the triangular wave carrier generation unit 250 and the converter 260 are provided as functional units.
  • the converter 260 limits the predetermined active power command value PE * and reactive power command value QE * when the first pulse switching command SW1 is output by the carrier frequency switching command unit 230.
  • the converter 260 changes the active power command value PE * from the active power upper limit command value + P * _lim to the active power lower limit command value ⁇ P * _lim.
  • the reactive power command value QE * is limited to a range from the reactive power upper limit command value + Q * _lim to the reactive power lower limit command value ⁇ Q * _lim.
  • the value of P * _lim is less than the rated active power of the power converter 10
  • the value of Q * _lim is less than the rated reactive power of the power converter 10.
  • the voltage command value calculation unit 220 calculates the cell voltage command value Vcl * based on the active power command value PE * and the reactive power command value QE * limited by the converter 260. As a result, it is possible to generate a gate signal that suppresses power loss proportional to the active power PE and the reactive power QE of the power converter 10.
  • the first pulse switching command SW1 is output, and the power converter 10 outputs the carrier command frequency fc * in the high frequency range (for example, the second frequency fc2 or the third frequency fc2).
  • the power loss of the power converter 10 can be reduced in the state where the switching is controlled by the frequency fc3).
  • the power converter 1 of the modification 4 is demonstrated with reference to drawings.
  • the carrier frequency switching command unit 230 of the converter control device 20 is based on the external command SYS output from the external system such as the protection device of the power conversion device 1 and the carrier command frequency fc.
  • the case of selecting the frequency as * has been described.
  • the carrier command frequency fc * is based on the signal output from another power conversion device 1 connected to the DC side in the system connected to the power conversion device 1.
  • symbol is attached
  • the 15 is a figure which shows an example of the usage environment of the power converter device 1 in the modification 4.
  • the power conversion device 1 ⁇ and the power conversion device 1 ⁇ are connected to one end and the other end of the DC system so as to face each other.
  • the power converter 1 ⁇ is provided at a connection point between the first AC system and the DC system, and mutually converts the AC power supplied by the first AC system and the DC power supplied by the DC system.
  • the power converter 1 ⁇ is provided at a connection point between the second AC system and the DC system, and mutually converts the AC power supplied by the second AC system and the DC power supplied by the DC system.
  • the first pulse output unit 233 outputs the first pulse switching command SW1 to the carrier frequency switching unit 240 and the other power conversion device 1. Moreover, in the modified example 4, the carrier frequency switching command unit 230 acquires the first pulse switching command SW1 output by another power conversion device 1 as the external command SYS.
  • the power conversion device 1 may be connected to, for example, two or more power conversion devices 1 via a DC system.
  • the power conversion device 1 of the modified example 4 selects the carrier command frequency fc * based on the external command SYS acquired from the other power conversion device 1, and the other power conversion device 1 in the opposite direction selects the carrier command frequency fc *.
  • the influence of the detected AC system fault on the self-device and the system connected to the self-device can be quickly settled. Therefore, the power conversion device 1 of Modification 4 can improve the operation continuity at the time of a system fault while reducing the power loss.

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Abstract

The power conversion device according to an embodiment has an arm unit in which one or more unit converters each including a capacitor and a switching element connected in parallel are connected in series. A generation unit selectively generates a triangular wave carrier signal having the frequency of any of a first frequency obtained by multiplying an AC frequency by a first non-integer value, a second frequency obtained by multiplying the AC frequency by a second non-integer value greater than or equal to the first non-integer value, and a third frequency higher than the second frequency. A control unit controls the switching element on the basis of the triangular wave carrier signal. A switching unit causes the triangular wave carrier signal having the first frequency to be generated if the absolute value of the AC voltage is within a predetermined range, causes the triangular wave carrier signal having the third frequency to be generated during a first period if the absolute value of the AC voltage is not within the predetermined range, and causes the triangular wave carrier signal having the second frequency to be generated during a second period if the generation unit is not generating the triangular wave carrier signal having the third frequency.

Description

電力変換装置、電力変換システム、電力変換方法、及びプログラムPOWER CONVERSION DEVICE, POWER CONVERSION SYSTEM, POWER CONVERSION METHOD, AND PROGRAM
 本発明の実施形態は、電力変換装置、電力変換システム、電力変換方法、及びプログラムに関する。 The embodiment of the present invention relates to a power conversion device, a power conversion system, a power conversion method, and a program.
 近年、電力変換装置として、モジュラー・マルチレベル変換器(以下、MMC変換器:Modular Multilevel Converter)の実用化が進められている。MMC変換器とは,直列に接続された複数の単位変換器を含むアームユニットを備え、各単位変換器の出力可能な電圧を加算することで高電圧,大容量に対応可能な電力変換装置である。電力変換装置は、例えば、交流系統と直流系統との間に接続され、電力を変換する。 In recent years, as a power converter, a modular multilevel converter (MMC converter: Modular Multilevel Converter) has been put into practical use. The MMC converter is a power conversion device that includes an arm unit that includes a plurality of unit converters connected in series, and is capable of handling high voltage and large capacity by adding the voltages that can be output from each unit converter. is there. The power conversion device is connected between, for example, an AC system and a DC system, and converts power.
 ここで、MMC変換器が、ハーフブリッジセル方式の2レベル変換器である単位変換器を備える場合、単位変換器のスイッチング制御には、PWM(Pulse Width Modulation)電圧を生成する変調方法として三角波キャリア比較方式が用いられる場合がある。この場合、三角波キャリア信号の周波数(つまり、単位変換器のスイッチング周波数)が、低周波であり、かつ、電力変換装置の連系する交流系統の周波数の整数倍に近づくと、ハーフブリッジセルのコンデンサ電圧のバランスを安定させることが困難になる場合がある。そこで、従来、三角波キャリア周波数を、交流系統周波数の2~4倍未満程度の非整数倍に設定したり、4倍以上に高周波化したりする技術が知られている。 Here, when the MMC converter includes a unit converter that is a half-bridge cell type two-level converter, switching control of the unit converter uses a triangular wave carrier as a modulation method for generating a PWM (Pulse Width Modulation) voltage. A comparison method may be used. In this case, when the frequency of the triangular wave carrier signal (that is, the switching frequency of the unit converter) is a low frequency and approaches an integral multiple of the frequency of the AC system interconnected with the power converter, the capacitor of the half bridge cell is It may be difficult to stabilize the voltage balance. Therefore, conventionally, there is known a technique of setting the triangular wave carrier frequency to a non-integer multiple of about 2 to less than 4 times the AC system frequency or increasing the frequency to 4 times or more.
 しかしながら、電力変換装置は、単位変換器あたりのスイッチング周波数が高くなると、電力変換に伴う電力損失の規模が大きくなるため、三角波キャリア周波数を交流系統周波数の4倍以上の高周波に設定した場合、電力変換装置の電力変換に伴う損失を低損失化することが困難である。一方、低損失化の観点から交流系統周波数の4倍未満の非整数倍に設定すると、低周波であるため電圧や電流の制御性能が低下する。このため、連系される交流系統や直流系統に系統事故が生じた場合、電力変換装置は、運転を継続することが困難になる場合がある。これに対応するために、三角波キャリア周波数を系統事故時に一時的に高周波に設定する技術が知られているが、電力変換に伴う損失による総発熱量が増大し続けたり、事故除去の後に速やかに運転を回復したりすることが困難になる場合があった。 However, in the power converter, when the switching frequency per unit converter becomes high, the scale of power loss accompanying power conversion becomes large. Therefore, when the triangular wave carrier frequency is set to a high frequency that is four times or more as high as the AC system frequency, It is difficult to reduce the loss due to the power conversion of the conversion device. On the other hand, if a non-integer multiple of less than 4 times the AC system frequency is set from the viewpoint of lowering the loss, the control performance of voltage and current deteriorates because of the low frequency. Therefore, when a system failure occurs in the AC system or DC system to be interconnected, it may be difficult for the power conversion device to continue operating. In order to deal with this, there is known a technique of temporarily setting the triangular wave carrier frequency to a high frequency in the event of a system fault, but the total heat generation amount due to the loss due to power conversion continues to increase, or immediately after the fault is cleared. It was sometimes difficult to recover driving.
国際公開第2009/086927号International Publication No. 2009/086927 特開2014-18015号公報JP-A-2014-18015 特開2018-133950号公報Japanese Patent Laid-Open No. 2018-133950
 本発明は、電力変換に係る電力損失を低減しつつ、系統事故時の運転継続性を向上させることができる、電力変換装置、電力変換システム、電力変換方法、及びプログラムを提供することを目的とする。 An object of the present invention is to provide a power conversion device, a power conversion system, a power conversion method, and a program that can improve the operation continuity at the time of a system fault while reducing the power loss related to power conversion. To do.
 本発明が解決しようとする課題は、電力変換に係る電力損失を低減しつつ、系統事故時の運転継続性を向上させることができる、電力変換装置、電力変換システム、電力変換方法、及びプログラムを提供することである。 An object of the present invention is to provide a power conversion device, a power conversion system, a power conversion method, and a program capable of improving the operation continuity at the time of a system fault while reducing the power loss related to power conversion. Is to provide.
 実施形態の電力変換装置は、直流と交流とを相互に変換可能な電力変換装置であって、アームユニットと、生成部と、制御部と、切替部とを持つ。アームユニットは、互いに並列に接続されるコンデンサとスイッチング素子とを含む単位変換器が少なくとも1つ以上直列に接続される。生成部は、前記交流の周波数に第1非整数値を乗じた第1周波数と、前記交流の周波数に前記第1非整数値以上の第2非整数値を乗じた第2周波数と、前記第2周波数より高い周波数である第3周波数とのうち、いずれかの周波数の三角波キャリア信号を選択的に生成する。制御部は、前記生成部によって生成された前記三角波キャリア信号に基づいて、前記スイッチング素子を制御する。切替部は、前記生成部に、いずれの周波数の前記三角波キャリア信号を生成させるかを切り替え、前記生成部に、前記交流の電圧の絶対値が所定範囲にある場合、前記第1周波数の三角波キャリア信号を生成させ、前記交流の電圧の絶対値が前記所定範囲にない場合、前記第3周波数の三角波キャリア信号を第1の期間の間、生成させ、前記交流の電圧の絶対値が前記所定範囲になく、且つ前記生成部が前記第3周波数の三角波キャリア信号を生成していない場合、前記第2周波数の三角波キャリア信号を第2の期間の間、生成させる。 The power converter of the embodiment is a power converter capable of mutually converting DC and AC, and has an arm unit, a generation unit, a control unit, and a switching unit. The arm unit is connected in series with at least one unit converter including a capacitor and a switching element that are connected in parallel with each other. The generating unit includes a first frequency obtained by multiplying the alternating current frequency by a first non-integer value, a second frequency obtained by multiplying the alternating current frequency by a second non-integer value equal to or greater than the first non-integer value, and the second frequency. A triangular wave carrier signal of any one of the third frequency, which is a frequency higher than two frequencies, is selectively generated. The control unit controls the switching element based on the triangular wave carrier signal generated by the generation unit. The switching unit switches to which frequency the triangular wave carrier signal is generated by the generation unit, and when the absolute value of the AC voltage is in a predetermined range, the switching unit switches the triangular wave carrier of the first frequency. When a signal is generated and the absolute value of the alternating voltage is not within the predetermined range, the triangular wave carrier signal of the third frequency is generated for the first period, and the absolute value of the alternating voltage is within the predetermined range. And the generator does not generate the triangular wave carrier signal of the third frequency, the triangular wave carrier signal of the second frequency is generated during the second period.
実施形態の電力変換装置1の構成の一例を示す図である。It is a figure which shows an example of a structure of the power converter device 1 of embodiment. 電力変換器10の構成の一例を示す図である。It is a figure which shows an example of a structure of the power converter 10. セルCLの構成の一例を示す図である。It is a figure which shows an example of a structure of the cell CL. 実施形態の交流情報算出部210の処理の一例を概念的に示す図である。It is a figure which shows notionally an example of a process of the alternating current information calculation part 210 of embodiment. 実施形態のキャリア周波数切替指令部230の処理の一例を概念的に示す図である。It is a figure which shows notionally an example of a process of the carrier frequency switching instruction | command part 230 of embodiment. 実施形態のキャリア周波数切替部240の処理の一例を概念的に示す図である。It is a figure which shows notionally an example of a process of the carrier frequency switching part 240 of embodiment. 第1周波数fc1、第2周波数fc2、及び第3周波数fc3と、第1の期間TM1、及び第2の期間TM2との関係の一例を示すグラフである。It is a graph which shows an example of the relation of the 1st frequency fc1, the 2nd frequency fc2, and the 3rd frequency fc3, and the 1st period TM1 and the 2nd period TM2. 変換器制御装置20が生成する各種信号の一例を示すグラフである。6 is a graph showing an example of various signals generated by the converter control device 20. 交流系統事故時の電力変換装置1の動作の一例を示す図である。It is a figure which shows an example of operation | movement of the power converter device 1 at the time of an AC system accident. 実施形態の電力変換装置1の動作の一例を示すフローチャート(その1)Flowchart showing an example of the operation of the power converter 1 of the embodiment (No. 1) 実施形態の電力変換装置1の動作の一例を示すフローチャート(その2)Flowchart showing an example of the operation of the power conversion device 1 of the embodiment (Part 2) 変形例1のキャリア周波数切替指令部230aの処理を概念的に示す図である。It is a figure which shows notionally the process of the carrier frequency switching instruction | command part 230a of the modification 1. 変形例2のキャリア周波数切替指令部230bの処理を概念的に示す図である。It is a figure which shows notionally the process of the carrier frequency switching instruction | command part 230b of the modification 2. 変形例3の変換器制御装置20bの構成の一例を示す図である。It is a figure which shows an example of a structure of the converter control apparatus 20b of the modification 3. 変形例4における電力変換装置1の使用環境の一例を示す図である。13 is a diagram showing an example of a usage environment of the power conversion device 1 in Modification Example 4. FIG.
 以下、実施形態の電力変換装置、電力変換システム、電力変換方法、及びプログラムを、図面を参照して説明する。 A power conversion device, a power conversion system, a power conversion method, and a program according to the embodiments will be described below with reference to the drawings.
(実施形態)
[電力変換装置1の構成]
 図1は、実施形態の電力変換装置1の構成の一例を示す図である。電力変換装置1は、交流系統と直流系統の連系点に設けられ、交流系統が供給する交流電力と、直流系統が供給する直流電力とを相互に変換する。電力変換装置1は、電力変換器10と、変換器制御装置20とを備える。
(Embodiment)
[Configuration of power conversion device 1]
FIG. 1 is a diagram illustrating an example of a configuration of a power conversion device 1 according to an embodiment. The power conversion device 1 is provided at an interconnection point between an AC system and a DC system, and mutually converts AC power supplied by the AC system and DC power supplied by the DC system. The power conversion device 1 includes a power converter 10 and a converter control device 20.
[電力変換器10について]
 電力変換器10は、変換器制御装置20の制御に基づいて、交流電力と直流電力とを相互に変換する。電力変換器10は、例えば、モジュラー・マルチレベル変換器(以下、MMC変換器:Modular Multilevel Converter)である。図2は、電力変換器10の構成の一例を示す図である。電力変換器10は、直流系統の正極(図示する端子P)と、直流系統の負極(図示する端子N)との間に複数のレグLGを備える。レグLGの数は、例えば、交流系統が供給する交流電力の相数に対応する。本実施形態では、交流系統は、第1相(図示するR相)、第2相(図示するS相)及び第3相(図示するT相)の三相三線式の交流電力を供給する。このため、電力変換器10は、R相に対応するレグLGrと、S相に対応するレグLGsと、T相に対応するレグLGtとを備える。以降の説明において、レグLGrと、レグLGsと、レグLGtとを互いに区別しない場合には、総称して「レグLG」と記載する。
[About the power converter 10]
The power converter 10 mutually converts AC power and DC power under the control of the converter control device 20. The power converter 10 is, for example, a modular multilevel converter (hereinafter, MMC converter: Modular Multilevel Converter). FIG. 2 is a diagram showing an example of the configuration of the power converter 10. The power converter 10 includes a plurality of legs LG between a positive electrode of the DC system (a terminal P shown in the figure) and a negative electrode of the DC system (a terminal N shown in the figure). The number of legs LG corresponds, for example, to the number of phases of AC power supplied by the AC system. In the present embodiment, the AC system supplies three-phase three-wire AC power of a first phase (R phase shown), a second phase (S phase shown), and a third phase (T phase shown). Therefore, the power converter 10 includes the leg LGr corresponding to the R phase, the leg LGs corresponding to the S phase, and the leg LGt corresponding to the T phase. In the following description, when the leg LGr, the leg LGs, and the leg LGt are not distinguished from each other, they are collectively referred to as “leg LG”.
 レグLGには、トランス(図示するトランスTR)を介して、交流系統が供給する交流電力の三相のうち、ある相が接続される。具体的には、レグLGrには、R相が接続され、レグLGsには、S相が接続され、レグLGtには、T相が接続される。以降の説明において、レグLGrと、R相との接続点を接続点CPrと記載し、レグLGsと、S相との接続点を接続点CPsと記載し、レグLGtと、T相との接続点を接続点CPtと記載する。以降の説明において、接続点CPrと、接続点CPsと、接続点CPtとを互いに区別しない場合には、単に接続点CPと記載する。 A certain phase of the three phases of AC power supplied by the AC system is connected to the leg LG via a transformer (a transformer TR shown in the figure). Specifically, the leg LGr is connected to the R phase, the leg LGs is connected to the S phase, and the leg LGt is connected to the T phase. In the following description, a connection point between the leg LGr and the R phase will be referred to as a connection point CPr, a connection point between the leg LGs and the S phase will be referred to as a connection point CPs, and a connection between the leg LGt and the T phase will be described. The point is described as a connection point CPt. In the following description, when the connection point CPr, the connection point CPs, and the connection point CPt are not distinguished from each other, they are simply referred to as the connection point CP.
 また、以降の説明において、電力変換器10が出力する直流電圧の端子Pと同電位となる部位を、レグLGの端子Pとも記載し、当該直流電圧の端子Nと同電位となる部位を、レグLGの端子Nとも記載する。また、レグLGの端子Pから各相の接続点までの間を正側アームユニットとも記載する。また、各相の接続点からレグLGの端子Nまでの間を負側アームユニットとも記載する。 Further, in the following description, a portion having the same potential as the terminal P of the DC voltage output by the power converter 10 is also referred to as a terminal P of the leg LG, and a portion having the same potential as the terminal N of the DC voltage, Also referred to as the terminal N of the leg LG. Further, a portion from the terminal P of the leg LG to the connection point of each phase is also referred to as a positive arm unit. Further, a portion from the connection point of each phase to the terminal N of the leg LG is also described as a negative arm unit.
 各レグLGは、互いに同様の構成を備える。以降の説明において、レグLGrに係る構成には、符号の末尾に「r」を付し、レグLGsに係る構成には、符号の末尾に「s」を付し、レグLGtに係る構成には、符号の末尾に「t」を付す。また、いずれのレグLGに係る構成であるかを互いに区別しない場合には、「r」、「s」、又は「t」を省略して示す。以下、各レグLGを代表してレグLGrについて説明する。 Each leg LG has the same configuration as each other. In the following description, the configuration related to the leg LGr is suffixed with “r”, the configuration related to the leg LGs is suffixed with “s”, and the configuration related to the leg LGt is suffixed to , "T" is added to the end of the code. In addition, when it is not necessary to distinguish which leg LG has the configuration, “r”, “s”, or “t” is omitted. Hereinafter, the leg LGr will be described on behalf of each leg LG.
 レグLGrは、正側アームユニットと、負側アームユニットとに、それぞれn個のセルCL(図示するセルCL1-1r~CL1-nr、及びセルCL2-1r~CL2-nr)と、複数のリアクトルRT(図示するリアクトルRT1r,RT2r)とを備える。nは、自然数である。レグLGrの正側アームユニットには、端子Pから接続点CPrに向けて、セルCL1-1r~CL1-nrと、リアクトルRT1rとが記載の順に直列接続される。また、レグLGrの負側アームユニットには、接続点CPrから端子Nに向けて、リアクトルRT2rと、セルCL2-1r~CL2-nrとが記載の順に直列に接続される。なお、リアクトルRTとトランスTRとは、リアクトルの機能を代替するだけの漏れリアクタンスを有する特殊な巻線構造のトランスに置き換えてもよい。 The leg LGr includes n cells CL (the illustrated cells CL1-1r to CL1-nr and cells CL2-1r to CL2-nr) and a plurality of reactors in the positive arm unit and the negative arm unit, respectively. RT (reactors RT1r, RT2r shown). n is a natural number. To the positive arm unit of the leg LGr, the cells CL1-1r to CL1-nr and the reactor RT1r are connected in series in the stated order from the terminal P toward the connection point CPr. Further, a reactor RT2r and cells CL2-1r to CL2-nr are connected in series from the connection point CPr to the terminal N in the negative arm unit of the leg LGr in the order shown. It should be noted that the reactor RT and the transformer TR may be replaced with a transformer having a special winding structure having a leak reactance sufficient to substitute the function of the reactor.
 なお、レグLGrは、接続点CPから端子Pに流れる正側アーム電流(図示する、R相正側電流Ipr)を検出する電流検出器(不図示)と、端子Nから接続点CPに流れる負側アーム電流(図示する、R相負側電流Inr)を検出する電流検出器と(不図示)とが設けられていてもよい。 The leg LGr includes a current detector (not shown) that detects a positive arm current (not shown, R-phase positive current Ipr) flowing from the connection point CP to the terminal P, and a negative current flowing from the terminal N to the connection point CP. A current detector (not shown) for detecting the side arm current (illustrated, R-phase negative side current Inr) may be provided.
[セルCLについて]
 図3は、セルCLの構成の一例を示す図である。セルCLとは、例えば、ハーフブリッジ回路である。図3に示される通り、セルCLは、例えば、複数のスイッチング素子Q(図示するスイッチング素子Q1~Q2)と、スイッチング素子Qに応じた数のダイオードD(図示するダイオードD1~D2)と、コンデンサCとを備える。スイッチング素子Qは、例えば、絶縁ゲートバイポーラトランジスタ(以下、IGBT:Insulated Gate Bipolar Transistor)である。ただし、スイッチング素子Qは、IGBTに限定されない。スイッチング素子Qは、コンバータ又はインバータを実現可能な自己消弧型スイッチング素子であれば、いかなる素子でもよい。本実施形態では、スイッチング素子QがIGBTである場合について説明する。
[About cell CL]
FIG. 3 is a diagram showing an example of the configuration of the cell CL. The cell CL is, for example, a half bridge circuit. As shown in FIG. 3, the cell CL includes, for example, a plurality of switching elements Q (illustrated switching elements Q1 to Q2), a number of diodes D (illustrated diodes D1 to D2) corresponding to the switching elements Q, and capacitors. And C. The switching element Q is, for example, an Insulated Gate Bipolar Transistor (IGBT). However, the switching element Q is not limited to the IGBT. The switching element Q may be any element as long as it is a self-turn-off switching element that can realize a converter or an inverter. In this embodiment, a case where the switching element Q is an IGBT will be described.
 スイッチング素子Q1と、スイッチング素子Q2とは、互いに直列に接続される。スイッチング素子Q1、及びスイッチング素子Q2と、コンデンサCとは、互いに並列に接続される。各スイッチング素子Qと、ダイオードDとは、互いに並列に接続される。具体的には、スイッチング素子Q1と、ダイオードD1とは、互いに並列に接続され、スイッチング素子Q2と、ダイオードD2とは、互いに並列に接続される。 The switching element Q1 and the switching element Q2 are connected in series with each other. The switching element Q1, the switching element Q2, and the capacitor C are connected in parallel with each other. Each switching element Q and the diode D are connected in parallel with each other. Specifically, the switching element Q1 and the diode D1 are connected in parallel with each other, and the switching element Q2 and the diode D2 are connected in parallel with each other.
 図3においてセルCLは、レグLGの端子P側に接続される正極端子と、端子N側に接続される負極端子とを備える。セルCLの正極端子は、スイッチング素子Q1と、スイッチング素子Q2との接続点に接続され、セルCLの負極端子は、スイッチング素子Q2のエミッタ端子に接続される。以降の説明において、セルCLの正極端子と負極端子との間に生じる電圧を、セル電圧Vclと記載する。 In FIG. 3, the cell CL includes a positive electrode terminal connected to the terminal P side of the leg LG and a negative electrode terminal connected to the terminal N side. The positive terminal of the cell CL is connected to the connection point between the switching element Q1 and the switching element Q2, and the negative terminal of the cell CL is connected to the emitter terminal of the switching element Q2. In the following description, the voltage generated between the positive electrode terminal and the negative electrode terminal of the cell CL will be referred to as the cell voltage Vcl.
 各スイッチング素子Qには、スイッチング素子Qのオン、オフを切り替える切替端子(不図示)を備え、切替端子は、変換器制御装置20と接続され、制御信号が入力される。具体的には、スイッチング素子Q1には、制御信号として第1ゲート信号gtpが入力され、スイッチング素子Q2には、制御信号として第2ゲート信号gtnが入力される。制御信号に基づいて各スイッチング素子Qがオン、又はオフに切り替えられることにより、セルCLが備えるコンデンサCは、充電又は放電される。また、セルCLは、コンデンサCの電圧であるコンデンサ電圧Vcを検出する電圧検出器(不図示)が設けられる。 Each switching element Q has a switching terminal (not shown) for switching the switching element Q on and off, and the switching terminal is connected to the converter control device 20 and a control signal is input. Specifically, the switching element Q1 receives the first gate signal gtp as a control signal, and the switching element Q2 receives the second gate signal gtn as a control signal. The capacitors C included in the cells CL are charged or discharged by switching each switching element Q on or off based on the control signal. Further, the cell CL is provided with a voltage detector (not shown) that detects the capacitor voltage Vc which is the voltage of the capacitor C.
 スイッチング素子Qのオン状態にする制御信号を「1」と表現し、オフ状態にする制御信号を「0」と表現すると、セル電圧Vclは、(gtp、gtn)=(1、0)の場合、コンデンサ電圧Vcと一致し、(gtp、gtn)=(0、1)の場合、0[V]である。このように、各レグLGが備えるスイッチング素子Qがスイッチングされることにより、マルチレベルの波形を生成することができる。 When the control signal for turning on the switching element Q is expressed as “1” and the control signal for turning off the switching element is expressed as “0”, the cell voltage Vcl is (gtp, gtn) = (1, 0) , Which is the same as the capacitor voltage Vc, and (gtp, gtn) = (0, 1), it is 0 [V]. In this way, by switching the switching element Q included in each leg LG, it is possible to generate a multi-level waveform.
 なお、スイッチング素子Qを(gtp、gtn)=(1、1)とすることは、コンデンサCを短絡するため、禁止である。また、スイッチング時においてスイッチング素子Qが過渡的に(gtp、gtn)=(1、1)となるのを防止するため、スイッチング素子Qは、通常はごく短時間、過渡的に(gtp、gtn)=(0、0)の状態(デッドタイム)に制御される。ただし、スイッチング素子Qが、(gtp、gtn)=(0、0)の状態(デッドタイム)に制御される時間は、スイッチング周期に比べて十分に短時間であるため、以降の説明から省略する。また、スイッチング素子Qのスイッチング制御を停止する場合、(gtp、gtn)=(0、0)の状態に固定することにより、実現される。 Note that setting the switching element Q to (gtp, gtn) = (1,1) is prohibited because it short-circuits the capacitor C. Further, in order to prevent the switching element Q from transiently (gtp, gtn) = (1, 1) during switching, the switching element Q is normally transiently (gtp, gtn) for a very short time. = (0, 0) is controlled (dead time). However, the time during which the switching element Q is controlled to the state (dead time) of (gtp, gtn) = (0, 0) is sufficiently shorter than the switching cycle, and therefore will be omitted from the following description. . Further, when the switching control of the switching element Q is stopped, it is realized by fixing the state of (gtp, gtn) = (0, 0).
[変換器制御装置20について]
 図1に戻り、変換器制御装置20は、制御部200と、ゲート信号生成部300とを備える。制御部200は、例えば、CPU(Central Processing Unit)等のハードウェアプロセッサが記憶部(不図示)に記憶されるプログラム(ソフトウェア)を実行することにより、交流情報算出部210と、電圧指令値演算部220と、キャリア周波数切替指令部230と、キャリア周波数切替部240と、三角波キャリア生成部250とを機能部として実現する。また、これらの構成要素のうち一部又は全部は、LSI(Large Scale Integration)やASIC(Application Specific Integrated Circuit)、FPGA(Field-Programmable Gate Array)、GPU(Graphics Processing Unit)等のハードウェア(回路部;circuitryを含む)によって実現されてもよいし、ソフトウェアとハードウェアの協働によって実現されてもよい。
[Converter controller 20]
Returning to FIG. 1, the converter control device 20 includes a control unit 200 and a gate signal generation unit 300. The control unit 200, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software) stored in a storage unit (not shown), the AC information calculation unit 210 and the voltage command value calculation. The unit 220, the carrier frequency switching command unit 230, the carrier frequency switching unit 240, and the triangular wave carrier generation unit 250 are realized as functional units. Some or all of these components are hardware (circuits) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit). Part; including circuitry), or may be realized by cooperation of software and hardware.
 交流情報算出部210は、交流系統の各相の電圧を検出する機器(図示する検出器CS)によって検出された電圧(図示するR相電圧Vr、S相電圧Vs、及びT相電圧Vt)を示す情報を取得し、取得した情報に基づいて、交流系統有効電圧Vd、及び交流系統無効電圧Vqを算出する。また、交流情報算出部210は、交流系統電圧に追従し、同期するための演算として、交流系統無効電圧Vqの算出値が零になるように演算を繰り返す。これにより、交流情報算出部210は、交流周波数fpll、及び交流系統電圧位相thetaを算出する。交流周波数fpllは、電力変換器10が連系する交流系統電圧の周波数である。また、交流系統電圧位相thetaは、当該交流電圧のある基準相の位相を示す値である。交流情報算出部210の処理の詳細については、後述する。 The AC information calculation unit 210 calculates the voltages (R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt shown) detected by a device (detector CS shown) that detects the voltage of each phase of the AC system. The information shown is acquired, and the AC system effective voltage Vd and the AC system reactive voltage Vq are calculated based on the acquired information. In addition, the AC information calculation unit 210 repeats the calculation as a calculation for following and synchronizing with the AC system voltage so that the calculated value of the AC system reactive voltage Vq becomes zero. Thereby, the AC information calculation unit 210 calculates the AC frequency fpll and the AC system voltage phase theta. The AC frequency fpll is the frequency of the AC system voltage with which the power converter 10 is interconnected. The AC system voltage phase theta is a value indicating the phase of a reference phase having the AC voltage. Details of the processing of the AC information calculation unit 210 will be described later.
 電圧指令値演算部220は、電力変換器10の各状態(例えば、正側電流Ipr~Ipt、負側電流Inr~Int、及び各コンデンサ電圧Vc)と、交流情報算出部210によって算出された、交流系統有効電圧Vd、交流系統無効電圧Vq、及び交流系統電圧位相thetaに基づいて、電力変換器10の出力する有効電力PEと、無効電力QEとが、予め定められた有効電力指令値PE*と、無効電力指令値QE*とになるように、各セルCLのセル電圧Vclを指示するセル電圧指令値Vcl*を算出する。 The voltage command value calculator 220 calculates each state of the power converter 10 (for example, the positive side currents Ipr to Ipt, the negative side currents Inr to Int, and each capacitor voltage Vc) and the AC information calculator 210. Based on the AC system active voltage Vd, the AC system reactive voltage Vq, and the AC system voltage phase theta, the active power PE output by the power converter 10 and the reactive power QE have a predetermined active power command value PE *. Then, the cell voltage command value Vcl * for instructing the cell voltage Vcl of each cell CL is calculated so that the reactive power command value QE * is obtained.
 キャリア周波数切替指令部230は、交流情報算出部210によって算出された交流系統有効電圧Vdと、外部システムからの指令(図示する外部指令SYS)とに基づいて、三角波キャリア信号の周波数を指示する信号(図示する第1パルス切替指令SW1、及び第2パルス切替指令SW2)を、キャリア周波数切替部240に出力する。三角波キャリア信号は、三角波比較方式によってスイッチング素子Qのスイッチング制御信号を生成する際に用いられる信号である。三角波比較方式において、三角波キャリア信号の周波数と、スイッチング周波数とは、一致する。以降の説明において、三角波キャリア信号の周波数を、スイッチング周波数とも記載する。外部システムは、例えば、電力変換装置1の保護装置である。キャリア周波数切替指令部230の処理の詳細については、後述する。 The carrier frequency switching command unit 230 is a signal that commands the frequency of the triangular wave carrier signal based on the AC system effective voltage Vd calculated by the AC information calculation unit 210 and a command from the external system (external command SYS shown). The first pulse switching command SW1 and the second pulse switching command SW2 shown in the figure are output to the carrier frequency switching unit 240. The triangular wave carrier signal is a signal used when the switching control signal of the switching element Q is generated by the triangular wave comparison method. In the triangular wave comparison method, the frequency of the triangular wave carrier signal and the switching frequency match. In the following description, the frequency of the triangular wave carrier signal is also referred to as the switching frequency. The external system is, for example, a protection device for the power conversion device 1. Details of the processing of the carrier frequency switching command unit 230 will be described later.
 キャリア周波数切替部240は、交流情報算出部210によって算出された交流周波数fpllと、キャリア周波数切替指令部230によって出力された第1パルス切替指令SW1、及び第2パルス切替指令SW2とに基づいて、電力変換器10のスイッチング周波数を指示する指令値(以下、キャリア指令周波数fc*)を選択し、三角波キャリア生成部250に出力する。キャリア周波数切替部240の処理の詳細については、後述する。 The carrier frequency switching unit 240, based on the AC frequency fpll calculated by the AC information calculation unit 210, the first pulse switching command SW1 and the second pulse switching command SW2 output by the carrier frequency switching command unit 230, A command value (hereinafter, carrier command frequency fc *) that indicates the switching frequency of the power converter 10 is selected and output to the triangular wave carrier generation unit 250. Details of the processing of the carrier frequency switching unit 240 will be described later.
 三角波キャリア生成部250は、キャリア周波数切替部240によって出力されたキャリア指令周波数fc*に基づいて、セルCL毎の三角波キャリア信号Tri*を生成する。この三角波キャリア信号Tri*は、アームユニットに直列に接続されるセルCLの一端から他端まで順に、セルCL毎に均等に位相シフトした信号である。 The triangular wave carrier generation unit 250 generates a triangular wave carrier signal Tri * for each cell CL based on the carrier command frequency fc * output by the carrier frequency switching unit 240. This triangular wave carrier signal Tri * is a signal in which the phase is uniformly shifted for each cell CL in order from one end to the other end of the cells CL connected in series to the arm unit.
 なお、三角波キャリア信号Tri*の位相シフト順は、必ずしもセルCLの直列接続順に一致している必要はなく、同一アームユニットに属する任意のセルCL間において、互いに均等に位相シフトしていればよい。したがって、三角波キャリア信号Tri*の位相シフト順は、任意に変更できる。以降の説明では、三角波キャリア信号Tri*の位相シフト順が、セルCLの直列接続順である場合を一例に説明する。 Note that the phase shift order of the triangular wave carrier signal Tri * does not necessarily have to match the serial connection order of the cells CL, as long as they are evenly phase-shifted between arbitrary cells CL belonging to the same arm unit. . Therefore, the phase shift order of the triangular wave carrier signal Tri * can be arbitrarily changed. In the following description, the case where the phase shift order of the triangular wave carrier signal Tri * is the series connection order of the cells CL will be described as an example.
 ゲート信号生成部300は、電圧指令値演算部220によって算出された各セルCLのセル電圧指令値Vcl*と、三角波キャリア生成部250によって生成されたセルCL毎の三角波キャリア信号Tri*とに基づいて、セルCL毎の第1ゲート信号gtp、及び第2ゲート信号gtnを生成し、電力変換器10に出力する。三角波キャリア生成部250によって生成される三角波キャリア信号Tri*と、第1ゲート信号gtp、及び第2ゲート信号gtnの詳細については、後述する。 The gate signal generation unit 300 is based on the cell voltage command value Vcl * of each cell CL calculated by the voltage command value calculation unit 220 and the triangular wave carrier signal Tri * for each cell CL generated by the triangular wave carrier generation unit 250. Then, the first gate signal gtp and the second gate signal gtn for each cell CL are generated and output to the power converter 10. Details of the triangular wave carrier signal Tri * generated by the triangular wave carrier generation unit 250, the first gate signal gtp, and the second gate signal gtn will be described later.
 以下、電力変換器10が備える各部の処理の内容について説明する。 Below, the contents of the processing of each part of the power converter 10 will be explained.
[交流情報算出部210について]
 図4は、実施形態の交流情報算出部210の処理の一例を概念的に示す図である。交流情報算出部210は、変換部211と、PI演算部212と、加算部213と、発振器214とを機能部として備える。
[About AC information calculation unit 210]
FIG. 4 is a diagram conceptually illustrating an example of processing of the AC information calculation unit 210 of the embodiment. The AC information calculation unit 210 includes a conversion unit 211, a PI calculation unit 212, an addition unit 213, and an oscillator 214 as functional units.
 変換部211は、検出器CSによって検出された電圧(図示するR相電圧Vr、S相電圧Vs、及びT相電圧Vt)を示す情報を取得する。変換部211は、式(1)を用いて、取得したR相電圧Vr、S相電圧Vs、及びT相電圧Vtを、交流系統有効電圧Vd、及び交流系統無効電圧Vqに変換(算出)する。なお、交流系統電圧位相thetaは、後述する発振器214によって出力される値であり、交流系統のある基準相(この一例では、R相)の電圧位相を示す値である。 The conversion unit 211 acquires information indicating the voltages (R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt shown) detected by the detector CS. The conversion unit 211 converts (calculates) the acquired R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt into an AC system effective voltage Vd and an AC system reactive voltage Vq, using Equation (1). . The AC system voltage phase theta is a value output by an oscillator 214 described later, and is a value indicating the voltage phase of a certain reference phase (R phase in this example) of the AC system.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
 PI演算部212は、変換部211によって変換された交流系統無効電圧Vqに基づいて、電力変換器10が連系する交流系統電圧の周波数と、基準交流系統周波数fs0との周波数差(以下、周波数差Δfpll)を算出する。周波数差Δfpllは、交流系統電圧の周波数が基準交流系統周波数fs0より高い場合、プラスの値をとり、基準交流系統周波数fs0より低い場合、マイナスの値をとる。基準交流系統周波数fs0は、連系する交流系統の定格周波数であり、例えば、50[Hz]、又は60[Hz]の定数である。周波数差Δfpllは、PI演算部212に入力される交流系統無効電圧Vqの算出値が零になるまで、増加、又は減少を続け、実際の交流系統周波数と基準交流系統周波数fs0との差の値に収束する。 The PI calculation unit 212, based on the AC system reactive voltage Vq converted by the conversion unit 211, the frequency difference between the frequency of the AC system voltage with which the power converter 10 is interconnected and the reference AC system frequency fs0 (hereinafter, referred to as frequency). The difference Δfpll) is calculated. The frequency difference Δfpll takes a positive value when the frequency of the AC system voltage is higher than the reference AC system frequency fs0, and takes a negative value when it is lower than the reference AC system frequency fs0. The reference AC system frequency fs0 is a rated frequency of the interconnected AC system, and is, for example, a constant of 50 [Hz] or 60 [Hz]. The frequency difference Δfpll continues to increase or decrease until the calculated value of the AC system reactive voltage Vq input to the PI calculation unit 212 becomes zero, and is the value of the difference between the actual AC system frequency and the reference AC system frequency fs0. Converge to.
 加算部213は、PI演算部212によって算出された周波数差Δfpllを、基準交流系統周波数fs0に加算する。以降の説明において、基準交流系統周波数fs0に周波数差Δfpllを加算した周波数を、交流周波数fpllと記載する。 The adder 213 adds the frequency difference Δfpll calculated by the PI calculator 212 to the reference AC system frequency fs0. In the following description, the frequency obtained by adding the frequency difference Δfpll to the reference AC system frequency fs0 is referred to as AC frequency fpll.
 発振器214は、加算部213によって算出された交流周波数fpllの周波数によって、最小値0から最大値2πまでを、繰り返し単調増加する交流系統電圧位相thetaを出力する。なお、上述したように、交流系統電圧位相thetaは、変換部211の交流系統有効電圧Vd、及び交流系統無効電圧Vqの変換と、セル電圧指令値Vcl*の生成とに用いられる。 The oscillator 214 outputs an AC system voltage phase theta that monotonically increases from the minimum value 0 to the maximum value 2π according to the frequency of the AC frequency fpll calculated by the adding unit 213. As described above, the AC system voltage phase theta is used for converting the AC system effective voltage Vd and the AC system reactive voltage Vq of the conversion unit 211 and for generating the cell voltage command value Vcl *.
 上述の処理によって、交流情報算出部210は、変換部211における交流系統無効電圧Vqの算出値が零になるように、交流系統電圧位相thetaの算出を繰り返すことで、交流系統電圧に同期した交流周波数fpll、及び交流系統電圧位相thetaを得る。 Through the above-described processing, the AC information calculation unit 210 repeats the calculation of the AC system voltage phase theta so that the calculated value of the AC system reactive voltage Vq in the conversion unit 211 becomes zero, and thus the AC system synchronized with the AC system voltage. The frequency fpll and the AC system voltage phase theta are obtained.
 後述するが、スイッチング素子Qは、交流周波数fpllに比例するようにスイッチング周波数が制御される場合がある。ここで、交流系統の状態が不安定となり、周波数差Δfpllが通常の範囲を逸脱して変動した場合、交流周波数の算出値fpllも同様に変動し、スイッチング素子Qのスイッチング周波数が通常の範囲を超えて、電力変換装置1が安定運転できなくなる恐れがある。これを防止するため、PI演算部212は、周波数差Δfpllが、限界値(以下、限界値Δfpll_limit)より大きい場合、周波数差Δfpllを+限界値Δfpll_limitとし、-限界値Δfpll_limitより小さい場合、周波数差Δfpllを-限界値Δfpll_limitとして出力してもよい。この場合、加算部213は、交流周波数fpllを、基準交流系統周波数fs0+限界値Δfpll_limit~基準交流系統周波数fs0-限界値Δfpll_limitの範囲の周波数に制限することができる。限界値Δfpll_limitは、例えば、基準交流系統周波数fs0より小さい正の値である。 As will be described later, the switching frequency of the switching element Q may be controlled so as to be proportional to the AC frequency fpll. Here, when the state of the AC system becomes unstable and the frequency difference Δfpll fluctuates outside the normal range, the calculated value fpll of the AC frequency also fluctuates, and the switching frequency of the switching element Q falls outside the normal range. Beyond that, there is a risk that the power conversion device 1 may not operate stably. To prevent this, the PI calculation unit 212 sets the frequency difference Δfpll to the + limit value Δfpll_limit when the frequency difference Δfpll is larger than the limit value (hereinafter, the limit value Δfpll_limit), and sets the frequency difference Δfpll_limit to the −limit value Δfpll_limit. Δfpll may be output as −limit value Δfpll_limit. In this case, the addition unit 213 can limit the AC frequency fpll to a frequency in the range of the reference AC system frequency fs0 + the limit value Δfpll_limit to the reference AC system frequency fs0−the limit value Δfpll_limit. The limit value Δfpll_limit is, for example, a positive value smaller than the reference AC system frequency fs0.
[キャリア周波数切替指令部230について]
 図5は、実施形態のキャリア周波数切替指令部230の処理の一例を概念的に示す図である。キャリア周波数切替指令部230は、第1比較器231と、判定部232と、第1パルス出力部233と、第2パルス出力部234とを機能部として備える。第1比較器231は、交流情報算出部210によって算出された交流系統有効電圧Vdの絶対値と、電圧上限値Vth_H、及び電圧下限値Vth_Lとを比較する。第1比較器231は、交流系統有効電圧Vdの絶対値が電圧上限値Vth_Hよりも大きい場合、或いは交流系統有効電圧Vdの絶対値が電圧下限値Vth_Lよりも小さい場合、系統電圧異常信号ERRを出力する。交流系統有効電圧Vdの絶対値が電圧上限値Vth_Hよりも大きい状態、或いは交流系統有効電圧Vdの絶対値が電圧下限値Vth_Lよりも小さい状態は、交流系統に系統事故が発生し、交流系統の各相電圧の振幅が異常値を示していたり、相間が不平衡になっていたりする状態である。電圧上限値Vth_Hから電圧下限値Vth_Lによって示される範囲は、交流系統有効電圧Vdの絶対値がとり得る「所定範囲」の一例である。
[About carrier frequency switching command unit 230]
FIG. 5: is a figure which shows notionally an example of a process of the carrier frequency switching instruction | command part 230 of embodiment. The carrier frequency switching command unit 230 includes a first comparator 231, a determination unit 232, a first pulse output unit 233, and a second pulse output unit 234 as functional units. The first comparator 231 compares the absolute value of the AC system effective voltage Vd calculated by the AC information calculation unit 210 with the voltage upper limit value Vth_H and the voltage lower limit value Vth_L. The first comparator 231 outputs the system voltage abnormality signal ERR when the absolute value of the AC system effective voltage Vd is larger than the voltage upper limit value Vth_H or when the absolute value of the AC system effective voltage Vd is smaller than the voltage lower limit value Vth_L. Output. When the absolute value of the AC system effective voltage Vd is larger than the voltage upper limit value Vth_H, or the absolute value of the AC system effective voltage Vd is smaller than the voltage lower limit value Vth_L, a system fault occurs in the AC system and the AC system This is a state in which the amplitude of each phase voltage shows an abnormal value or the phases are unbalanced. The range indicated by the voltage upper limit value Vth_H to the voltage lower limit value Vth_L is an example of a “predetermined range” that the absolute value of the AC system effective voltage Vd can take.
 なお、第1比較器231は、式(2)によって求められる合成電圧ベクトルVdqと、所定の閾値とを比較し、合成電圧ベクトルVdqの値が所定の上限閾値より大きいか、所定の下限閾値より小さい場合、系統電圧異常信号ERRを出力する構成であってもよい。 The first comparator 231 compares the combined voltage vector Vdq obtained by the equation (2) with a predetermined threshold value, and the value of the combined voltage vector Vdq is greater than a predetermined upper threshold value or less than a predetermined lower threshold value. If it is smaller, the system voltage abnormality signal ERR may be output.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
 判定部232は、第1比較器231によって系統電圧異常信号ERRが出力されたか否か、又は又は外部システムによって外部指令SYSが出力されたか否かを判定する。判定部232は、系統電圧異常信号ERR、又は外部指令SYSのうち、いずれか一方が出力される場合、第1パルス出力部233に系統電圧異常信号ERRを出力する。 The determination unit 232 determines whether or not the system voltage abnormality signal ERR has been output by the first comparator 231 or whether the external command SYS has been output by the external system. The determination unit 232 outputs the system voltage abnormality signal ERR to the first pulse output unit 233 when either the system voltage abnormality signal ERR or the external command SYS is output.
 第1パルス出力部233は、判定部232によって系統電圧異常信号ERRが出力される場合、系統電圧異常信号ERRが出力されてから第1の期間TM1だけ、第1パルス切替指令SW1を出力する。また、第1パルス出力部233は、第1比較器231によって系統事故を検知していない場合であっても、外部指令SYSが出力された場合には、第1パルス切替指令SW1を出力する。 When the determination unit 232 outputs the system voltage abnormality signal ERR, the first pulse output unit 233 outputs the first pulse switching command SW1 only for the first period TM1 after the system voltage abnormality signal ERR is output. Further, the first pulse output unit 233 outputs the first pulse switching command SW1 when the external command SYS is output even when the first comparator 231 does not detect a system fault.
 第2パルス出力部234は、第1比較器231によって系統電圧異常信号ERRが出力される場合、系統電圧異常信号ERRが出力されてから第2の期間TM2だけ、第2パルス切替指令SW2を出力する。 When the system voltage abnormality signal ERR is output by the first comparator 231, the second pulse output unit 234 outputs the second pulse switching command SW2 only for the second period TM2 after the system voltage abnormality signal ERR is output. To do.
[キャリア周波数切替部240について]
 図6は、実施形態のキャリア周波数切替部240の処理の一例を概念的に示す図である。キャリア周波数切替部240は、第1切替部241と、乗算部242と、第2切替部243とを機能部として備える。第1切替部241は、乗算部242に出力する非整数値を、第1非整数値N1と、第2非整数値N2とのいずれか一方に切り替える。第1切替部241は、第1パルス切替指令SW1が出力されていない場合、乗算部242に第1非整数値N1を出力し、第1パルス切替指令SW1が出力されている場合、第2非整数値N2を出力する。第1非整数値N1、及び第2非整数値N2は、正の値であり、且つ整数ではない値である。また、第1非整数値N1は、第2非整数値N2よりも小さい値である。
[About carrier frequency switching unit 240]
FIG. 6 is a diagram conceptually illustrating an example of processing of the carrier frequency switching unit 240 of the embodiment. The carrier frequency switching unit 240 includes a first switching unit 241, a multiplication unit 242, and a second switching unit 243 as functional units. The first switching unit 241 switches the non-integer value output to the multiplication unit 242 to either one of the first non-integer value N1 and the second non-integer value N2. The first switching unit 241 outputs the first non-integer value N1 to the multiplication unit 242 when the first pulse switching command SW1 is not output, and the second non-integer value N1 when the first pulse switching command SW1 is output. The integer value N2 is output. The first non-integer value N1 and the second non-integer value N2 are positive values that are not integers. In addition, the first non-integer value N1 is a value smaller than the second non-integer value N2.
 乗算部242は、交流周波数fpllと、第1切替部241によって出力された非整数値とを乗算する。以降の説明において、交流周波数fpllと、第1非整数値N1とを乗算した周波数を、第1周波数fc1と記載し、交流周波数fpllと、第2非整数値N2とを乗算した周波数を、第2周波数fc2と記載する。 The multiplying unit 242 multiplies the AC frequency fpll by the non-integer value output by the first switching unit 241. In the following description, the frequency obtained by multiplying the AC frequency fpll by the first non-integer value N1 is referred to as the first frequency fc1, and the frequency obtained by multiplying the AC frequency fpll by the second non-integer value N2 is referred to as the first frequency fc1. It is described as 2 frequencies fc2.
 第2切替部243は、キャリア指令周波数fc*として三角波キャリア生成部250に出力する周波数を、乗算部242によって出力された周波数(第1周波数fc1、又は第2周波数fc2)と、第3周波数fc3とのいずれか一方に切り替える。第2切替部243は、第2パルス切替指令SW2が出力されていない場合、乗算部242によって出力された第1周波数fc1、又は第2周波数fc2をキャリア指令周波数fc*として出力し、第2パルス切替指令SW2が出力されている場合、第3周波数fc3をキャリア指令周波数fc*として出力する。第3周波数fc3は、予め定められた周波数である。 The second switching unit 243 sets the frequency output to the triangular wave carrier generation unit 250 as the carrier command frequency fc * to the frequency output by the multiplication unit 242 (first frequency fc1 or second frequency fc2) and the third frequency fc3. And switch to either one of. When the second pulse switching command SW2 is not output, the second switching unit 243 outputs the first frequency fc1 or the second frequency fc2 output by the multiplication unit 242 as the carrier command frequency fc *, and the second pulse When the switching command SW2 is output, the third frequency fc3 is output as the carrier command frequency fc *. The third frequency fc3 is a predetermined frequency.
 以下、第1周波数fc1、第2周波数fc2、及び第3周波数fc3と、第1の期間TM1、及び第2の期間TM2の関係について説明する。図7は、第1周波数fc1、第2周波数fc2、及び第3周波数fc3と、第1の期間TM1、及び第2の期間TM2との関係の一例を示すグラフである。図7の横軸は、キャリア指令周波数fc*を示し、縦軸は、当該キャリア指令周波数fc*のスイッチング周波数によって継続して制御することが可能な時間(以下、継続制御時間)を示し、波形W1は、キャリア指令周波数fc*と、継続制御時間との関係を示す波形である。 Hereinafter, the relationship between the first frequency fc1, the second frequency fc2, and the third frequency fc3, and the first period TM1 and the second period TM2 will be described. FIG. 7 is a graph showing an example of the relationship between the first frequency fc1, the second frequency fc2, the third frequency fc3, and the first period TM1 and the second period TM2. The horizontal axis of FIG. 7 shows the carrier command frequency fc *, and the vertical axis shows the time (hereinafter, continuous control time) that can be continuously controlled by the switching frequency of the carrier command frequency fc *. W1 is a waveform showing the relationship between the carrier command frequency fc * and the continuous control time.
 一般に、電力変換器10は、キャリア指令周波数fc*が増加するほど、単位時間当たりの発熱量(つまり、電力変換損失)が発生し、電力変換損失が大きいほど、継続制御時間は短くなる。したがって、電力変換損失に伴う許容発熱量を固定した場合、波形W1に示す通り、キャリア指令周波数fc*と、継続制御時間との関係は、おおむね反比例の関係となる。 Generally, in the power converter 10, as the carrier command frequency fc * increases, the amount of heat generation per unit time (that is, power conversion loss) occurs, and the larger the power conversion loss, the shorter the continuous control time. Therefore, when the allowable heat generation amount due to the power conversion loss is fixed, the relationship between the carrier command frequency fc * and the continuous control time is approximately inversely proportional as shown by the waveform W1.
 また、一般に、キャリア指令周波数fc*が、定数K×交流周波数fpll以下の低周波域において、交流周波数fpllの整数倍、又は整数倍に近い値をとると、電力変換器10は、コンデンサ電圧Vcのバランスの維持が困難になる。一方、キャリア指令周波数fc*が、定数K×交流周波数fpllより高いの高周波域において、交流周波数fpllの整数倍、又は整数倍に近い値をとる場合であっても、電力変換器10は、コンデンサ電圧Vcのバランスを維持することができる。定数Kは、例えば、「4」以上の値であり、第1非整数値N1、及び第2非整数値N2は、定数K未満の値である。つまり、第1非整数値N1、第2非整数値N2は、例えば、「2」~「4」程度の非整数値(例えば、2.1~2.9や、3.1~3.9)である。 Further, in general, when the carrier command frequency fc * takes a value that is an integer multiple of the AC frequency fpll or a value close to an integer multiple in the low frequency region of the constant K × AC frequency fpll or less, the power converter 10 causes the capacitor voltage Vc It becomes difficult to maintain the balance. On the other hand, even if the carrier command frequency fc * takes an integer multiple of the AC frequency fpll or a value close to an integer multiple in a high frequency region higher than the constant K × AC frequency fpll, the power converter 10 uses the capacitor. The balance of the voltage Vc can be maintained. The constant K is, for example, a value of “4” or more, and the first non-integer value N1 and the second non-integer value N2 are values less than the constant K. That is, the first non-integer value N1 and the second non-integer value N2 are, for example, non-integer values of about “2” to “4” (for example, 2.1 to 2.9 and 3.1 to 3.9). ).
 第1周波数fc1、及び第2周波数fc2は、定数K×交流周波数fpll以下の低周波域の周波数であるが、交流周波数fpllに、第1非整数値N1、又は第2非整数値N2を乗じた周波数である。このため、電力変換器10は、第1周波数fc1、又は第2周波数fc2のキャリア指令周波数fc*のスイッチング周波数によってスイッチング制御を行っても、コンデンサ電圧Vcのバランスを維持することができる。 The first frequency fc1 and the second frequency fc2 are frequencies in a low frequency region equal to or less than a constant K × AC frequency fpll, but the AC frequency fpll is multiplied by a first non-integer value N1 or a second non-integer value N2. Frequency. Therefore, the power converter 10 can maintain the balance of the capacitor voltage Vc even if switching control is performed by the switching frequency of the carrier command frequency fc * of the first frequency fc1 or the second frequency fc2.
 なお、キャリア指令周波数fc*が第2非整数値N2×交流周波数fpllである場合のスイッチング損失が小さい場合、第2非整数値N2と、第1非整数値N1との差を十分に小さくする、又は第2非整数値N2と、第1非整数値N1との差を「0」(つまり、第2非整数値N2=第1非整数値N1)にしてもよい。 When the switching loss when the carrier command frequency fc * is the second non-integer value N2 × AC frequency fpll is small, the difference between the second non-integer value N2 and the first non-integer value N1 is made sufficiently small. Alternatively, the difference between the second non-integer value N2 and the first non-integer value N1 may be “0” (that is, the second non-integer value N2 = the first non-integer value N1).
 第3周波数fc3は、第1周波数fc1、及び第2周波数fc2よりも高い周波数であり、定数K×交流周波数fpll以上の高周波域の周波数である。第3周波数fc3は、交流周波数fpllの整数倍であってもよく、交流周波数fpllの非整数倍であってもよい。なお、上述では、第3周波数fc3が予め定められた周波数(つまり、固定値)である場合について説明したが、交流周波数fpllに定数K以上の整数、又は定数K以上の非整数を乗じた値であってもよい。 The third frequency fc3 is a frequency higher than the first frequency fc1 and the second frequency fc2, and is a frequency in a high frequency range equal to or higher than the constant K × AC frequency fpll. The third frequency fc3 may be an integral multiple of the AC frequency fpll or a non-integer multiple of the AC frequency fpll. In the above description, the case where the third frequency fc3 is a predetermined frequency (that is, a fixed value) has been described. However, a value obtained by multiplying the AC frequency fpll by an integer equal to or greater than a constant K or a non-integer equal to or greater than the constant K May be
 以下、第1の期間TM1、及び第2の期間TM2の関係について説明する。上述したように、キャリア周波数切替部240は、第2パルス切替指令SW2が出力されている第2の期間TM2の間(つまり、系統事故が継続している時間相当の間)、第3周波数fc3をキャリア指令周波数fc*として出力する。第3周波数fc3は、高周波域の周波数であるため、単位時間あたりの電力損失が大きい。このため、電力変換器10は、長期間運転継続することが困難である。したがって、キャリア周波数切替部240は、短期間(この一例では、第2の期間TM2)、第3周波数fc3を出力する。 Hereinafter, the relationship between the first period TM1 and the second period TM2 will be described. As described above, the carrier frequency switching unit 240 has the third frequency fc3 during the second period TM2 in which the second pulse switching command SW2 is output (that is, during the time period during which the system fault continues). Is output as the carrier command frequency fc *. The third frequency fc3 is a frequency in a high frequency range, and thus has a large power loss per unit time. Therefore, it is difficult for the power converter 10 to continue operating for a long period of time. Therefore, the carrier frequency switching unit 240 outputs the third frequency fc3 for a short period (in this example, the second period TM2).
 第2の期間TM2は、例えば、交流系統に設けられる交流遮断器が、事故回線を切り離し、事故が除去されるまでの期間である。第2の期間TM2は、過去の事故事例や、予め定められた復旧時間に基づいて設定されてもよく、例えば、交流系統電圧周期の数倍程度の期間である。なお、第2の期間TM2は、電力変換器10が備える冷却機能に応じて、第3周波数fc3におけるスイッチング制御による発熱を冷却可能な期間であってもよい。 The second period TM2 is, for example, a period until the AC circuit breaker provided in the AC system disconnects the fault circuit and the fault is eliminated. The second period TM2 may be set based on a past accident case or a predetermined recovery time, and is, for example, a period of several times the AC system voltage cycle. The second period TM2 may be a period during which heat generated by switching control at the third frequency fc3 can be cooled according to the cooling function of the power converter 10.
 また、キャリア周波数切替部240は、第2パルス切替指令SW2が出力されておらず、且つ第1パルス切替指令SW1が出力されている間(つまり、系統事故が発生してから第2の期間TM2が経過した後の第1の期間TM1-第2の期間TM2の間、又は外部指令SYSを受信した後の第1の期間TM1の間)、第2周波数fc2をキャリア指令周波数fc*として出力する。第2周波数fc2は、第3周波数fc3よりも低周波域の周波数であるため、単位時間当たりの電力損失が第3周波数fc3に比して小さい。このため、電力変換器10は、第3周波数fc3よりも長期間、電力変換器10を運転継続することができる。したがって、第1の期間TM1は、第2の期間TM2よりも長い期間である。 In addition, the carrier frequency switching unit 240 outputs the second pulse switching command SW2 and does not output the first pulse switching command SW1 (that is, the second period TM2 after the occurrence of the system fault). The second frequency fc2 is output as the carrier command frequency fc * during the first period TM1 to the second period TM2 after the lapse of time or during the first period TM1 after receiving the external command SYS). . Since the second frequency fc2 is a frequency in the lower frequency range than the third frequency fc3, the power loss per unit time is smaller than that of the third frequency fc3. Therefore, the power converter 10 can continue to operate the power converter 10 for a longer period than the third frequency fc3. Therefore, the first period TM1 is longer than the second period TM2.
 また、上述したように、キャリア周波数切替部240は、第1パルス切替指令SW1、及び第2パルス切替指令SW2が出力されていない場合(つまり、通常状態において)、第1周波数fc1をキャリア指令周波数fc*として出力する。電力変換器10は、第1周波数fc1によって常時スイッチング制御が可能なだけの冷却機能を有する。 In addition, as described above, the carrier frequency switching unit 240 sets the first frequency fc1 to the carrier command frequency when the first pulse switching command SW1 and the second pulse switching command SW2 are not output (that is, in the normal state). Output as fc *. The power converter 10 has a cooling function that allows constant switching control with the first frequency fc1.
[ゲート信号について]
 図8は、変換器制御装置20が生成する各種信号の一例を示すグラフである。図8において、波形W11は、電力変換器10のあるアームユニットに直列に接続されるセルCLのうち、あるj番目(jは、自然数)のセルCL(以下、セルCL(j))の第1ゲート信号gtp(j)の生成に用いられる三角波キャリア信号Tri(j)*の経時変化を示す波形である。波形W12は、セルCL(j)の正極端子と負極端子との間に生じる電圧の指令値であるセル電圧指令値Vcl*の経時変化を示す波形である。波形W13は、セルCL(j)に隣接して直列に接続されるセルCL(以下、セルCL(j+1))の第1ゲート信号gtp(j+1)の生成に用いられる三角波キャリア信号Tri(j+1)*の経時変化を示す波形である。波形W14は、セルCL(j+1)の正極端子と負極端子との間に生じる電圧の指令値であるセル電圧指令値Vcl(j+1)*の経時変化を示す波形である。波形W15は、第1ゲート信号gtp(j)の経時変化を示す波形である。波形W16は、第1ゲート信号gtp(j+1)の経時変化を示す波形である。
[About gate signal]
FIG. 8 is a graph showing an example of various signals generated by the converter control device 20. In FIG. 8, a waveform W11 indicates a j-th (j is a natural number) cell CL (hereinafter, cell CL (j)) of the cell CL connected in series to a certain arm unit of the power converter 10. It is a waveform showing the change over time of the triangular wave carrier signal Tri (j) * used for generating the 1-gate signal gtp (j). The waveform W12 is a waveform showing a change over time of the cell voltage command value Vcl * which is a command value of the voltage generated between the positive electrode terminal and the negative electrode terminal of the cell CL (j). The waveform W13 is the triangular wave carrier signal Tri (j + 1) used to generate the first gate signal gtp (j + 1) of the cell CL (hereinafter, cell CL (j + 1)) connected in series adjacent to the cell CL (j). It is a waveform showing the change with time of *. A waveform W14 is a waveform showing a temporal change of a cell voltage command value Vcl (j + 1) *, which is a command value of a voltage generated between the positive electrode terminal and the negative electrode terminal of the cell CL (j + 1). The waveform W15 is a waveform showing the change over time of the first gate signal gtp (j). The waveform W16 is a waveform showing the change over time of the first gate signal gtp (j + 1).
 波形W11、及び波形W13が示す通り、三角波キャリア信号Tri(j)*と、三角波キャリア信号Tri(j+1)*は、周期が1/キャリア指令周波数fc*の三角波波形である。図8において、三角波キャリア信号Tri(j)*は、最大値がセルCLのコンデンサ電圧Vcに一致するように無次元化し、0から1の範囲によって示される。また、波形W12、及び波形W14が示す通り、セル電圧指令値Vcl(j)*と、セル電圧指令値Vcl(j+1)*の値は、ほぼ等しい。なお、セル電圧指令値Vcl(j)*は、三角波キャリア信号Tri*と同様に、セルCLのコンデンサ電圧Vcを基準に無次元化され、0から1の範囲によって示される。 As shown by the waveforms W11 and W13, the triangular wave carrier signal Tri (j) * and the triangular wave carrier signal Tri (j + 1) * are triangular wave waveforms having a cycle of 1 / carrier command frequency fc *. In FIG. 8, the triangular wave carrier signal Tri (j) * is made dimensionless so that the maximum value thereof coincides with the capacitor voltage Vc of the cell CL, and is shown by the range of 0 to 1. Further, as shown by the waveforms W12 and W14, the cell voltage command value Vcl (j) * and the cell voltage command value Vcl (j + 1) * are substantially equal. The cell voltage command value Vcl (j) * is made dimensionless with the capacitor voltage Vc of the cell CL as a reference, and is represented by a range of 0 to 1, like the triangular wave carrier signal Tri *.
 ゲート信号生成部300は、位相シフトPWM(Pulse Width Modulation)にて、第1ゲート信号gtp、及び第2ゲート信号gtnを生成する。波形W11、及び波形W13が示す通り、ゲート信号生成部300は、アームユニット毎のセルCL数をn個とすると、アームユニットの各セルCLに割り当てる三角波キャリア信号Tri*の位相を互いに2π/nずつシフトさせる。nは、アームユニットに直列に接続されるセルCLの個数(この一例では、n[個])である。したがって、位相の隣接するセルCL(j)、及びセルCL(j+1)の、三角波キャリア信号Tri(j)*、及び三角波キャリア信号Tri(j+1)*は、1/(n×fc*)の時間だけずれが生じる。 The gate signal generation unit 300 generates the first gate signal gtp and the second gate signal gtn by phase shift PWM (Pulse Width Modulation). As shown by the waveforms W11 and W13, when the number of cells CL for each arm unit is n, the gate signal generator 300 sets the phases of the triangular wave carrier signals Tri * assigned to the cells CL of the arm units to 2π / n. Shift one by one. n is the number of cells CL (n [pieces] in this example) connected in series to the arm unit. Therefore, the triangular wave carrier signal Tri (j) * and the triangular wave carrier signal Tri (j + 1) * of the cell CL (j) and the cell CL (j + 1) adjacent in phase have a time of 1 / (n × fc *). Just a gap occurs.
 ゲート信号生成部300は、三角波キャリア信号Tri(j)*と、セル電圧指令値Vcl(j)*とを比較し、Vcl(j)*<Tri(j)*の場合、第1ゲート信号gtp(j)を「0」(つまり、セルCL(j)のスイッチング素子Q1をオフ状態)に変化させ、Vcl(j)*>Tri(j)*の場合、第1ゲート信号gtp(j)を「1」(つまり、セルCL(j)のスイッチング素子Q1をオン状態)に変化させる。また、ゲート信号生成部300は、同様に三角波キャリア信号Tri(j+1)*と、セル電圧指令値Vcl(j+1)*とを比較し、第1ゲート信号gtp(j+1)を変化させる。なお、スイッチング素子Q2の第2ゲート信号gtnは、第1ゲート信号gtpの論理反転信号である。 The gate signal generation unit 300 compares the triangular wave carrier signal Tri (j) * with the cell voltage command value Vcl (j) *, and when Vcl (j) * <Tri (j) *, the first gate signal gtp. (J) is changed to “0” (that is, the switching element Q1 of the cell CL (j) is turned off), and when Vcl (j) *> Tri (j) *, the first gate signal gtp (j) is changed. It is changed to "1" (that is, the switching element Q1 of the cell CL (j) is turned on). Similarly, the gate signal generation unit 300 compares the triangular wave carrier signal Tri (j + 1) * with the cell voltage command value Vcl (j + 1) * to change the first gate signal gtp (j + 1). The second gate signal gtn of the switching element Q2 is a logical inversion signal of the first gate signal gtp.
 このようにゲート信号生成部300によって生成された第1ゲート信号gtp、及び第2ゲート信号gtnに基づいて、電力変換器10は、アームユニット内の各セルCLの第1ゲート信号gtpの変化タイミングをずらすことによって、当該アームユニットの合成電圧として最大nレベルのマルチレベル電圧を発生させる。 Based on the first gate signal gtp and the second gate signal gtn generated by the gate signal generator 300, the power converter 10 determines the change timing of the first gate signal gtp of each cell CL in the arm unit. Is shifted to generate a multi-level voltage of maximum n levels as a combined voltage of the arm unit.
[事故時の動作について]
 図9は、交流系統事故時の電力変換装置1の動作の一例を示す図である。波形W21~W23は、交流系統の各相の交流電圧の経時変化を示す波形である。波形W24は、交流系統有効電圧Vdの経時変化を示す波形である。波形W25は、第1パルス切替指令SW1の経時変化を示す波形である。波形W26は、第2パルス切替指令SW2の経時変化を示す波形である。波形W27は、キャリア指令周波数fc*の経時変化を示す波形である。波形W28は、コンデンサ電圧Vcの最大値を示す波形である。波形W29は、コンデンサ電圧Vcの最小値を示す波形である。
[About operation in case of an accident]
FIG. 9: is a figure which shows an example of operation | movement of the power converter device 1 at the time of an AC system accident. Waveforms W21 to W23 are waveforms showing changes with time of the AC voltage of each phase of the AC system. The waveform W24 is a waveform showing a change with time of the AC system effective voltage Vd. The waveform W25 is a waveform showing the change over time of the first pulse switching command SW1. The waveform W26 is a waveform showing the change over time of the second pulse switching command SW2. The waveform W27 is a waveform showing the change over time of the carrier command frequency fc *. The waveform W28 is a waveform showing the maximum value of the capacitor voltage Vc. The waveform W29 is a waveform showing the minimum value of the capacitor voltage Vc.
 交流系統事故が発生する以前(図示する時刻t0以前)において、波形W21~W23によって示される各相の交流電圧は、相間が平衡しており、且つ周波数が基準交流系統周波数fs0とほぼ等しい。また、波形W24によって示される通り、この時の交流系統有効電圧Vdは、交流電圧の振幅の絶対値を示す一定値である。また、キャリア周波数切替部240は、通常状態においてキャリア指令周波数fc*として第1周波数fc1を出力する。 Before the AC system accident occurs (before the time t0 shown in the figure), the AC voltage of each phase shown by the waveforms W21 to W23 is balanced between the phases, and the frequency is almost equal to the reference AC system frequency fs0. Further, as shown by the waveform W24, the AC system effective voltage Vd at this time is a constant value indicating the absolute value of the amplitude of the AC voltage. Further, the carrier frequency switching unit 240 outputs the first frequency fc1 as the carrier command frequency fc * in the normal state.
 時刻t0において、交流系統に事故が発生することに伴い、波形W21~W23によって示される交流系統の各相の交流電圧のうち、ある相(この一例では、R相)の電圧が、ほぼ0[V]に低下する。R相と健全な他の2相(この一例では、S相、T相)は、不平衡となる。これに伴い、交流系統有効電圧Vdは、基準交流系統周波数fs0のおおよそ2倍の周波数で振動し、電圧下限値Vth_Lを下回る。 At time t0, with the occurrence of an accident in the AC system, the voltage of a certain phase (in this example, the R phase) of the AC voltage of each phase of the AC system indicated by the waveforms W21 to W23 is almost 0 [. V]. The R phase and the other two healthy phases (S phase and T phase in this example) are unbalanced. Along with this, the AC system effective voltage Vd oscillates at a frequency approximately twice the reference AC system frequency fs0, and falls below the voltage lower limit value Vth_L.
 交流系統有効電圧Vdが電圧下限値Vth_Lを下回ることにより、キャリア周波数切替指令部230は、第1の期間TM1だけ第1パルス切替指令SW1を出力し、第2の期間TM2だけ第2パルス切替指令SW2を出力する。キャリア周波数切替部240は、第2パルス切替指令SW2が出力されている間(つまり、第2の期間TM2)、キャリア指令周波数fc*として第3周波数fc3を出力する。 When the AC system effective voltage Vd falls below the voltage lower limit value Vth_L, the carrier frequency switching command unit 230 outputs the first pulse switching command SW1 only for the first period TM1 and the second pulse switching command only for the second period TM2. Output SW2. The carrier frequency switching unit 240 outputs the third frequency fc3 as the carrier command frequency fc * while the second pulse switching command SW2 is being output (that is, the second period TM2).
 波形W28~W29に示されるように、事故発生直後の外乱によって、アームユニット内のコンデンサ電圧Vcのばらつき(波形W28と波形W29との間に生じる差分)が増加するが、電力変換器10は、第3周波数fc3の三角波キャリア信号Tri*に基づく、高い時間分解能の第1ゲート信号gtp、及び第2ゲート信号gtnによって制御されることにより、コンデンサ電圧Vcのばらつきを増加させることなく、早急に収束させることができる。 As shown by the waveforms W28 to W29, the disturbance immediately after the occurrence of the accident increases the variation in the capacitor voltage Vc in the arm unit (the difference generated between the waveform W28 and the waveform W29). Controlled by the first gate signal gtp and the second gate signal gtn with high time resolution based on the triangular wave carrier signal Tri * of the third frequency fc3, the capacitor voltage Vc converges quickly without increasing the variation. Can be made.
 一般に、コンデンサ電圧Vcのばらつきが増加されると、コンデンサ電圧Vcが、過電圧レベルまで到達し、電力変換器10の動作が停止してしまう場合がある。この場合、電力変換器10は、コンデンサCを放電させ、コンデンサ電圧Vcが通常レベルに戻るまでの間、運転再開することができない。上述の処理によれば、電力変換器10は、短期間(第2の期間TM2)だけ第3周波数fc3によってスイッチング制御を行うため、コンデンサ電圧Vcを上昇させることなく、運転継続性を向上することができる。 Generally, when the variation of the capacitor voltage Vc is increased, the capacitor voltage Vc may reach the overvoltage level and the operation of the power converter 10 may stop. In this case, the power converter 10 cannot restart the operation until the capacitor C is discharged and the capacitor voltage Vc returns to the normal level. According to the above-described processing, the power converter 10 performs the switching control with the third frequency fc3 for a short period (second period TM2), so that the operation continuity is improved without increasing the capacitor voltage Vc. You can
 次に、時刻t1において事故が除去されると、交流系統有効電圧Vdが一時的に電圧上限値Vth_Hを上回る場合がある。交流系統有効電圧Vdが上昇すると、それが外乱となり、アームユニット内のコンデンサ電圧Vcのばらつきが再び増加する。図9において、時刻t1頃に第2パルス切替指令SW2が停止し、キャリア周波数切替部240は、第1パルス切替指令SW1のみを出力する。第1パルス切替指令SW1のみが出力される期間は、時刻t1から時刻t2までの間(つまり、第1の期間TM1-第2の期間TM2の間)である。キャリア周波数切替部240は、第1パルス切替指令SW1が出力されている間(つまり、第2の期間TM2終了後、第2の期間TM2-第1の期間TM1の間)、キャリア指令周波数fc*として第2周波数fc2を出力する。 Next, when the accident is removed at time t1, the AC system effective voltage Vd may temporarily exceed the voltage upper limit value Vth_H. When the AC system effective voltage Vd rises, it becomes a disturbance, and the variation of the capacitor voltage Vc in the arm unit increases again. In FIG. 9, the second pulse switching command SW2 is stopped around time t1, and the carrier frequency switching unit 240 outputs only the first pulse switching command SW1. The period during which only the first pulse switching command SW1 is output is from time t1 to time t2 (that is, between the first period TM1 and the second period TM2). The carrier frequency switching unit 240 outputs the carrier command frequency fc * while the first pulse switching command SW1 is being output (that is, during the second period TM2 to the first period TM1 after the end of the second period TM2). And outputs the second frequency fc2.
 波形W28~W29に示されるように、事故除去後の交流系統有効電圧Vdの一時的な上昇によって、アームユニット内のコンデンサ電圧Vcのばらつきが増加するが、電力変換器10は、第2周波数fc2の三角波キャリア信号Tri*に基づく、通常状態よりも高い時間分解能の第1ゲート信号gtp、及び第2ゲート信号gtnによって制御されることにより、コンデンサ電圧Vcのばらつきを増加させることなく、早急に収束させることができる。 As shown by the waveforms W28 to W29, although the variation in the capacitor voltage Vc in the arm unit increases due to the temporary increase in the AC system effective voltage Vd after the accident elimination, the power converter 10 uses the second frequency fc2. Is controlled by the first gate signal gtp and the second gate signal gtn, which have a higher time resolution than in the normal state based on the triangular wave carrier signal Tri *, and converge quickly without increasing the variation in the capacitor voltage Vc. Can be made.
 上述の処理によれば、電力変換器10は、短期間(第1の期間TM1)だけ第2周波数fc2によってスイッチング制御を行うため、コンデンサ電圧Vcを上昇させることなく、運転継続性を向上することができる。 According to the above-described processing, the power converter 10 performs the switching control with the second frequency fc2 only for a short period (first period TM1), so that the operation continuity is improved without increasing the capacitor voltage Vc. You can
 次に、時刻t2において、第1パルス切替指令SW1が停止し、キャリア周波数切替部240は、第1周波数fc1をキャリア指令周波数fc*として出力する。これにより、電力変換器10は、通常状態において、低周波域のキャリア指令周波数fc*によって、電力変換効率を低下させることなく、且つコンデンサ電圧Vcのバランスを維持して安定に運転することができる。 Next, at time t2, the first pulse switching command SW1 is stopped, and the carrier frequency switching unit 240 outputs the first frequency fc1 as the carrier command frequency fc *. As a result, in the normal state, the power converter 10 can be stably operated by the carrier command frequency fc * in the low frequency range without lowering the power conversion efficiency and maintaining the balance of the capacitor voltage Vc. .
 なお、時刻t1において事故が除去されることに伴い、交流系統有効電圧Vdが一時的に電圧上限値Vth_Hを上回るが、キャリア周波数切替指令部230は、時刻t0直後に第1パルス切替指令SW1、及び第2パルス切替指令SW2を出力済みであるため、このタイミングにおいて再度第1パルス切替指令SW1、及び第2パルス切替指令SW2を出力しない。ただし、キャリア周波数切替指令部230は、時刻t0において交流系統有効電圧Vdが電圧下限値Vth_Lを下回らなかった場合などには、このタイミングにおいて、第1パルス切替指令SW1、及び第2パルス切替指令SW2を出力してもよい。 Although the AC system effective voltage Vd temporarily exceeds the voltage upper limit value Vth_H due to the elimination of the accident at the time t1, the carrier frequency switching command unit 230 causes the first pulse switching command SW1, immediately after the time t0. Since the second pulse switching command SW2 has already been output, the first pulse switching command SW1 and the second pulse switching command SW2 are not output again at this timing. However, when the AC system effective voltage Vd does not fall below the voltage lower limit value Vth_L at time t0, the carrier frequency switching command unit 230, at this timing, the first pulse switching command SW1 and the second pulse switching command SW2. May be output.
[処理フロー]
 図10、図11は、実施形態の電力変換装置1の動作の一例を示すフローチャート(その1)~(その2)である。図10に示されるフローチャートと、図11に示されるフローチャートとは、同時並行で実行される。図10において、まず、変換部211は、検出器CSから交流系統の各相の電圧(R相電圧Vr、S相電圧Vs、及びT相電圧Vt)を示す情報を取得する(ステップS100)。変換部211は、取得した交流系統の各相の電圧に基づいて、交流系統有効電圧Vd、及び交流系統無効電圧Vqに変換する(ステップS102)。加算部213は、PI演算部212が交流系統無効電圧Vqに基づいて算出した周波数差Δfpllに、基準交流系統周波数fs0を加算し、交流周波数fpllを算出する(ステップS104)。また、発振器214は、加算部213によって算出された交流周波数fpllの周波数によって、最小値0から最大値2πまでを、繰り返し単調増加する交流系統電圧位相thetaを出力する(ステップS106)。
[Processing flow]
10 and 11 are flowcharts (No. 1) to (No. 2) showing an example of the operation of the power conversion device 1 of the embodiment. The flowchart shown in FIG. 10 and the flowchart shown in FIG. 11 are executed simultaneously in parallel. In FIG. 10, first, the conversion unit 211 acquires information indicating the voltage (R-phase voltage Vr, S-phase voltage Vs, and T-phase voltage Vt) of each phase of the AC system from the detector CS (step S100). The conversion unit 211 converts the AC system valid voltage Vd and the AC system reactive voltage Vq based on the acquired voltage of each phase of the AC system (step S102). The addition unit 213 adds the reference AC system frequency fs0 to the frequency difference Δfpll calculated by the PI calculation unit 212 based on the AC system reactive voltage Vq to calculate the AC frequency fpll (step S104). Further, the oscillator 214 outputs an AC system voltage phase theta that monotonically increases from the minimum value 0 to the maximum value 2π according to the frequency of the AC frequency fpll calculated by the adding unit 213 (step S106).
 第1比較器231は、変換部211によって変換された交流系統有効電圧Vdの絶対値と、電圧上限値Vth_H、及び電圧下限値Vth_Lとを比較し、交流系統有効電圧Vdの絶対値が、電圧上限値Vth_H~電圧下限値Vth_Lの所定範囲内であるかを比較する(ステップS108)。判定部232は、第1比較器231の比較結果が交流系統有効電圧Vdの絶対値が所定範囲内であることを示す場合、外部システムから外部指令SYSを受信したか否かを判定する(ステップS110)。判定部232は、外部システムから外部指令SYSを受信していない場合、処理を終了する。第1パルス出力部233は、判定部232の判定結果が外部指令SYSを受信したことを示す場合、第1パルス切替指令SW1を出力し、処理をステップS116に進める。 The first comparator 231 compares the absolute value of the AC system effective voltage Vd converted by the conversion unit 211 with the voltage upper limit value Vth_H and the voltage lower limit value Vth_L, and the absolute value of the AC system effective voltage Vd is the voltage. It is compared whether it is within a predetermined range from the upper limit value Vth_H to the voltage lower limit value Vth_L (step S108). When the comparison result of the first comparator 231 indicates that the absolute value of the AC system effective voltage Vd is within the predetermined range, the determination unit 232 determines whether or not the external command SYS is received from the external system (step S110). The determination unit 232 ends the process when the external command SYS is not received from the external system. When the determination result of the determination unit 232 indicates that the external command SYS is received, the first pulse output unit 233 outputs the first pulse switching command SW1 and advances the process to step S116.
 第1比較器231は、交流系統有効電圧Vdの絶対値が所定範囲外であることを示す場合、系統電圧異常信号ERRを出力する(ステップS114)。第1パルス出力部233は、系統電圧異常信号ERRが出力されることに伴い、第1パルス切替指令SW1を出力し、第2パルス出力部234は、系統電圧異常信号ERRが出力されることに伴い、第2パルス切替指令SW2を出力する(ステップS114)。なお、ステップS114において、第1パルス切替指令SW1と、第2パルス切替指令SW2とが出力されるタイミングは、一致する。 If the absolute value of the AC system effective voltage Vd is outside the predetermined range, the first comparator 231 outputs the system voltage abnormality signal ERR (step S114). The first pulse output unit 233 outputs the first pulse switching command SW1 along with the output of the system voltage abnormality signal ERR, and the second pulse output unit 234 outputs the system voltage abnormality signal ERR. Accordingly, the second pulse switching command SW2 is output (step S114). Note that, in step S114, the timings at which the first pulse switching command SW1 and the second pulse switching command SW2 are output match.
 第2パルス出力部234は、第2パルス切替指令SW2を出力してから第2の期間TM2が経過するまでの間、第2パルス切替指令SW2を出力し続ける(ステップS116)。第2パルス出力部234は、第2パルス切替指令SW2を出力してから、第2の期間TM2が経過した後、第2パルス切替指令SW2を停止する(ステップS118)。第1パルス出力部233は、第1パルス切替指令SW1を出力してから、第1の期間TM1が経過するまでの間、第1パルス切替指令SW1を出力し続ける(ステップS120)。第1パルス出力部233は、第1パルス切替指令SW1を出力してから、第1の期間TM1が経過した後、第1パルス切替指令SW1を停止する(ステップS122)。 The second pulse output unit 234 continues to output the second pulse switching command SW2 from the time the second pulse switching command SW2 is output until the second period TM2 elapses (step S116). The second pulse output unit 234 stops the second pulse switching command SW2 after the second period TM2 has elapsed after outputting the second pulse switching command SW2 (step S118). The first pulse output unit 233 continues to output the first pulse switching command SW1 until the first period TM1 elapses after outputting the first pulse switching command SW1 (step S120). The first pulse output unit 233 stops the first pulse switching command SW1 after the first period TM1 has elapsed after outputting the first pulse switching command SW1 (step S122).
 図11に示す通り、キャリア周波数切替部240は、第2パルス切替指令SW2が出力されているか否かを判定する(ステップS200)。キャリア周波数切替部240は、第2パルス切替指令SW2が出力されている場合、第3周波数fc3をキャリア指令周波数fc*として出力する(ステップS202)。キャリア周波数切替部240は、第2パルス切替指令SW2が出力されていない場合、第1パルス切替指令SW1が出力されているか否かを判定する(ステップS204)。さらに、キャリア周波数切替部240は、第1パルス切替指令SW1が出力されている場合、第2周波数fc2をキャリア指令周波数fc*として出力する(ステップS206)。キャリア周波数切替部240は、第1パルス切替指令SW1、及び第2パルス切替指令SW2が出力されていない場合、第1周波数fc1をキャリア指令周波数fc*として出力する(ステップS208)。 As shown in FIG. 11, the carrier frequency switching unit 240 determines whether or not the second pulse switching command SW2 is output (step S200). When the second pulse switching command SW2 is output, the carrier frequency switching unit 240 outputs the third frequency fc3 as the carrier command frequency fc * (step S202). When the second pulse switching command SW2 is not output, the carrier frequency switching unit 240 determines whether the first pulse switching command SW1 is output (step S204). Furthermore, when the first pulse switching command SW1 is output, the carrier frequency switching unit 240 outputs the second frequency fc2 as the carrier command frequency fc * (step S206). When the first pulse switching command SW1 and the second pulse switching command SW2 are not output, the carrier frequency switching unit 240 outputs the first frequency fc1 as the carrier command frequency fc * (step S208).
 三角波キャリア生成部250は、キャリア周波数切替部240から出力されたキャリア指令周波数fc*に基づいて、セルCL毎の三角波キャリア信号Tri*を生成する(ステップS210)。電圧指令値演算部220は、交流情報算出部210によって算出された交流系統有効電圧Vd、交流系統無効電圧Vq、及び交流系統電圧位相theta等に基づいて、セルCL毎のセル電圧指令値Vcl*を生成する(ステップS212)。ゲート信号生成部300は、三角波キャリア生成部250によって生成された三角波キャリア信号Tri*と、電圧指令値演算部220によって生成されたセル電圧指令値Vcl*とに基づいて、セルCL毎の第1ゲート信号gtp、及び第2ゲート信号gtnを生成する(ステップS214)。電力変換器10は、ゲート信号生成部300によって生成された第1ゲート信号gtp、及び第2ゲート信号gtnに基づいて、スイッチング素子Qをスイッチング制御し、電力を変換する。 The triangular wave carrier generation unit 250 generates the triangular wave carrier signal Tri * for each cell CL based on the carrier command frequency fc * output from the carrier frequency switching unit 240 (step S210). The voltage command value calculation unit 220, based on the AC system effective voltage Vd, the AC system reactive voltage Vq, the AC system voltage phase theta, and the like calculated by the AC information calculation unit 210, the cell voltage command value Vcl * for each cell CL. Is generated (step S212). The gate signal generation unit 300, based on the triangular wave carrier signal Tri * generated by the triangular wave carrier generation unit 250 and the cell voltage command value Vcl * generated by the voltage command value calculation unit 220, the first for each cell CL. The gate signal gtp and the second gate signal gtn are generated (step S214). The power converter 10 performs switching control of the switching element Q based on the first gate signal gtp and the second gate signal gtn generated by the gate signal generation unit 300, and converts power.
[実施形態のまとめ]
 以上説明したように、本実施形態の電力変換装置1は、通常時において、低周波域のキャリア指令周波数fc*によって電力変換器10を制御することにより、電力変換損失を低減しつつ、コンデンサ電圧Vcのバランスが崩れることを抑制することができる。また、本実施形態の電力変換装置1は、系統事故時において、高周波域のキャリア指令周波数fc*によって短期間、電力変換器10を制御することにより、電力変換損失の積算値である総発熱量が増加することを抑制しつつ、コンデンサ電圧Vcが、過電圧レベルに達することを抑制することができる。したがって、本実施形態の電力変換装置1は、電力変換に係る電力損失を低減しつつ、系統事故時の運転継続性を向上させることができる。
[Summary of Embodiments]
As described above, the power conversion device 1 of the present embodiment controls the power converter 10 by the carrier command frequency fc * in the low frequency range in the normal time, thereby reducing the power conversion loss and reducing the capacitor voltage. It is possible to prevent the balance of Vc from being lost. In addition, the power conversion device 1 of the present embodiment controls the power converter 10 for a short period of time by the carrier command frequency fc * in the high frequency range at the time of a system fault, so that the total heat generation amount that is the integrated value of the power conversion loss. It is possible to prevent the capacitor voltage Vc from reaching the overvoltage level while suppressing an increase in the voltage. Therefore, the power conversion device 1 of the present embodiment can improve the operation continuity at the time of a system fault while reducing the power loss related to the power conversion.
 また、本実施形態の電力変換装置1は、系統事故が起きたタイミングと、系統事故がある程度収束したタイミングとにおいて、異なる高周波域のキャリア指令周波数fc*を用いて電力変換器10を制御することにより、電力変換損失の積算値である総発熱量が増加することを、より抑制することができる。また、本実施形態の電力変換装置1は、キャリア指令周波数fc*が高周波域であるほど、キャリア指令周波数fc*による電力変換器10の制御をより短期間で終了するように制御することによって、電力変換損失の積算値である総発熱量が増加することを、より抑制することができる。さらに、系統事故が起きた最も運転継続性への影響が大きいタイミングで、最も高周波のキャリア指令周波数fc*を用いて電力変換器10を制御することで、より運転継続性を向上させることができる。 Further, the power conversion device 1 of the present embodiment controls the power converter 10 by using the carrier command frequency fc * in different high frequency regions at the timing when the system fault occurs and the timing when the system fault converges to some extent. As a result, it is possible to further suppress an increase in the total heat generation amount, which is the integrated value of the power conversion loss. Further, the power conversion device 1 of the present embodiment controls the power converter 10 by the carrier command frequency fc * so as to finish in a shorter period as the carrier command frequency fc * is in a higher frequency range. It is possible to further suppress an increase in the total heat generation amount that is the integrated value of the power conversion loss. Furthermore, by controlling the power converter 10 using the carrier command frequency fc * having the highest frequency at the timing when the system fault has the greatest influence on the operation continuity, the operation continuity can be further improved. .
 また、本実施形態の電力変換装置1は、外部システムから受信した外部指令SYSに基づいて、高周波域のキャリア指令周波数fc*によって電力変換器10を制御する。これにより、本実施形態の電力変換装置1は、電力変換装置1の外部保護装置等が電力変換装置1に先行して、又は、単独で系統事故などの異常を検知した場合も迅速に、電力変換装置1が運転継続できるように電力変換器10を制御することができる。 Further, the power conversion device 1 of the present embodiment controls the power converter 10 by the carrier command frequency fc * in the high frequency range based on the external command SYS received from the external system. As a result, the power conversion device 1 according to the present embodiment can quickly perform power conversion when the external protection device or the like of the power conversion device 1 precedes the power conversion device 1 or independently detects an abnormality such as a system accident. The power converter 10 can be controlled so that the converter 1 can continue operation.
 また、本実施形態の電力変換装置1は、上述したように電力変換損失の増加を抑制し、電力変換器10の冷却機能を小容量化することによって、電力変換装置1を低コスト、及び小型化することができる。 Further, the power conversion device 1 of the present embodiment suppresses an increase in power conversion loss and reduces the cooling function of the power converter 10 as described above, thereby reducing the power conversion device 1 cost and size. Can be converted.
(変形例1)
 以下、図面を参照して変形例1のキャリア周波数切替指令部230aについて説明する。実施形態では、キャリア周波数切替指令部230は、系統電圧異常信号ERRと、外部指令SYSとに基づいて、第1パルス切替指令SW1と、第2パルス切替指令SW2とを出力する場合について説明した。変形例1のキャリア周波数切替指令部230aでは、更に、交流系統有効電圧Vdが電圧上限値Vth_Hから電圧下限値Vth_Lによって示される範囲を逸脱した状態の回数(以下、カウント回数ct)に基づいて、第1パルス切替指令SW1と、第2パルス切替指令SW2とを出力する場合について説明する。なお、上述した実施形態と同様の構成については、同一の符号を付して説明を省略する。
(Modification 1)
Hereinafter, with reference to the drawings, the carrier frequency switching command unit 230a of the first modification will be described. In the embodiment, the case where the carrier frequency switching command unit 230 outputs the first pulse switching command SW1 and the second pulse switching command SW2 based on the system voltage abnormality signal ERR and the external command SYS has been described. In the carrier frequency switching command unit 230a of Modification Example 1, further, based on the number of times (hereinafter, the number of counts ct) that the AC system effective voltage Vd deviates from the range indicated by the voltage upper limit value Vth_H and the voltage lower limit value Vth_L, A case where the first pulse switching command SW1 and the second pulse switching command SW2 are output will be described. The same components as those of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.
 図12は、変形例1のキャリア周波数切替指令部230aの処理を概念的に示す図である。変形例1のキャリア周波数切替指令部230aは、キャリア周波数切替指令部230が備える各機能部に代えて(或いは、加えて)、第1比較器231と、判定部232aと、第1パルス出力部233と、第2パルス出力部234と、回数カウンタ235と、第2比較器236と、第3比較器237とを機能部として備える。回数カウンタ235は、第1比較器231の比較結果が、交流系統有効電圧Vdが電圧上限値Vth_Hを上回ったこと、又は電圧下限値Vth_Lを下回ったことを示した情報に基づいて、ある設定時間内(例えば、10秒)での系統電圧異常状態の回数をカウントし、カウント回数ctを第2比較器236と、第3比較器237とに出力する。 FIG. 12 is a diagram conceptually showing the process of the carrier frequency switching command unit 230a of the first modification. The carrier frequency switching command unit 230a of the first modification is replaced with (or in addition to) the functional units included in the carrier frequency switching command unit 230, and the first comparator 231, the determination unit 232a, and the first pulse output unit. 233, a second pulse output unit 234, a number counter 235, a second comparator 236, and a third comparator 237 are provided as functional units. The frequency counter 235 sets a certain set time based on the information indicating that the comparison result of the first comparator 231 indicates that the AC system effective voltage Vd exceeds the voltage upper limit value Vth_H or falls below the voltage lower limit value Vth_L. The number of abnormalities in the system voltage within 10 seconds (for example, 10 seconds) is counted, and the counted number ct is output to the second comparator 236 and the third comparator 237.
 なお、回数カウンタ235は、交流系統有効電圧Vdが細かく振動し、カウント対象の設定時間よりも十分に短い別のある設定時間(例えば、1[秒])の間に、何度も電圧上限値Vth_Hから電圧下限値Vth_Lによって示される範囲を逸脱したり当該範囲内に戻ったりした場合には、それらがまとめて1回の系統電圧異常状態とカウントする。 It should be noted that the frequency counter 235 repeatedly measures the voltage upper limit value during another set time (for example, 1 [second]) that is sufficiently shorter than the set time of the count target because the AC system effective voltage Vd vibrates finely. When Vth_H deviates from the range indicated by the voltage lower limit value Vth_L or returns to the range, they are collectively counted as one system voltage abnormal state.
 第2比較器236は、回数カウンタ235によって出力されたカウント回数ctと、切替回数第1上限値SW_lim1とを比較する。第2比較器236は、カウント回数ctが切替回数第1上限値SW_lim1を上回っていない場合、「False」信号を出力し、カウント回数ctが切替回数第1上限値SW_lim1を上回っている場合、「True」信号を出力する。 The second comparator 236 compares the count number ct output by the number counter 235 with the switching number first upper limit value SW_lim1. The second comparator 236 outputs a "False" signal when the count number ct does not exceed the switching number first upper limit value SW_lim1, and when the count number ct exceeds the switching number first upper limit value SW_lim1, " True ”signal.
 第3比較器237は、回数カウンタ235によって出力されたカウント回数ctと、切替回数第2上限値SW_lim2とを比較する。第3比較器237は、カウント回数ctが切替回数第2上限値SW_lim2を上回っていない場合、「False」信号を出力し、カウント回数ctが切替回数第2上限値SW_lim2を上回っている場合、「True」信号を出力する。 The third comparator 237 compares the count number ct output by the number counter 235 with the switching number second upper limit value SW_lim2. The third comparator 237 outputs a "False" signal when the count number ct does not exceed the switching number second upper limit value SW_lim2, and when the count number ct exceeds the switching number second upper limit value SW_lim2, " True ”signal.
 判定部232aは、第1比較器231によって系統電圧異常信号ERRが出力されており、第2比較器236から「False」信号が出力されているか否かを判定する。第1パルス出力部233は、判定部232aによって、系統電圧異常信号ERR、及び「False」信号が出力されている場合(つまり、カウント回数ctが切替回数第1上限値SW_lim1を上回っていない場合)、第1の期間TM1だけ第1パルス切替指令SW1を出力する。また、変形例1の第1パルス出力部233は、系統電圧異常信号ERRが出力されている場合であっても、第2比較器236によって「True」信号が出力されている場合(つまり、カウント回数ctが切替回数第1上限値SW_lim1を超過した場合)には、第1パルス切替指令SW1を出力しない。切替回数第1上限値SW_lim1は、電力変換器10を第2周波数fc2によって制御可能な回数を示す値である。 The determination unit 232a determines whether the first comparator 231 outputs the system voltage abnormality signal ERR and the second comparator 236 outputs the “False” signal. The first pulse output unit 233 outputs the system voltage abnormality signal ERR and the “False” signal by the determination unit 232a (that is, the count number ct does not exceed the switching number first upper limit value SW_lim1). , And outputs the first pulse switching command SW1 only during the first period TM1. In addition, the first pulse output unit 233 of the modified example 1 outputs the “True” signal by the second comparator 236 even when the system voltage abnormality signal ERR is output (that is, the count). When the number of times ct exceeds the switching number first upper limit value SW_lim1), the first pulse switching command SW1 is not output. The switching count first upper limit value SW_lim1 is a value indicating the number of times the power converter 10 can be controlled by the second frequency fc2.
 判定部232aは、第1比較器231によって系統電圧異常信号ERRが出力されており、第3比較器237から「False」信号が出力されているか否かを判定する。第2パルス出力部234は、判定部232aによって、系統電圧異常信号ERR、及び「False」信号が出力されている場合(つまり、カウント回数ctが切替回数第2上限値SW_lim2を上回っていない場合)、第2の期間TM2だけ第2パルス切替指令SW2を出力する。また、変形例1の第2パルス出力部234は、系統電圧異常信号ERRが出力されている場合であっても、第3比較器237によって「True」信号が出力されている場合(つまり、カウント回数ctが切替回数第2上限値SW_lim2を超過した場合)には、第2パルス切替指令SW2を出力しない。切替回数第2上限値SW_lim2は、電力変換器10を第3周波数fc3によって制御可能な回数を示す値である。 The determination unit 232a determines whether or not the system voltage abnormality signal ERR is output by the first comparator 231 and the “False” signal is output from the third comparator 237. The second pulse output unit 234 outputs the system voltage abnormality signal ERR and the “False” signal by the determination unit 232a (that is, the count number ct does not exceed the switching number second upper limit SW_lim2). , And outputs the second pulse switching command SW2 only during the second period TM2. In addition, the second pulse output unit 234 of the modified example 1 outputs the “True” signal by the third comparator 237 even when the system voltage abnormality signal ERR is output (that is, the count). When the number of times ct exceeds the switching number second upper limit value SW_lim2), the second pulse switching command SW2 is not output. The switching count second upper limit value SW_lim2 is a value indicating the number of times the power converter 10 can be controlled by the third frequency fc3.
 なお、切替回数第1上限値SW_lim1と、切替回数第2上限値SW_lim2とは、同じ値であってもよく、互いに異なる値であってもよい。また、切替回数第1上限値SW_lim1、及び切替回数第2上限値SW_lim2は、回数に代えて(或いは、加えて)、時間(期間)によって示されてもよい。この場合、上限値は、電力変換器10を第2周波数fc2、又は第3周波数fc3によって制御可能な時間(期間)を示す値である。切替回数第1上限値SW_lim1は、「第2所定回数」の一例であり、切替回数第2上限値SW_lim2は、「第1所定回数」の一例である。 Note that the switching count first upper limit value SW_lim1 and the switching count second upper limit value SW_lim2 may be the same value or different values. Further, the switching number first upper limit value SW_lim1 and the switching number second upper limit value SW_lim2 may be indicated by time (period) instead of (or in addition to) the number of times. In this case, the upper limit value is a value indicating a time (period) during which the power converter 10 can be controlled by the second frequency fc2 or the third frequency fc3. The switching number first upper limit value SW_lim1 is an example of the “second predetermined number”, and the switching number second upper limit value SW_lim2 is an example of the “first predetermined number”.
 また、キャリア周波数切替部240は、カウント回数ctが切替回数第1上限値SW_lim1を上回っている、又は切替回数第3上限SW_lim3を上回っている場合、交流系統有効電圧Vdの絶対値が所定範囲を超えても、キャリア指令周波数fc*として第1周波数fc1を選択する。この場合、切替回数第1上限値SW_lim1、又は切替回数第3上限SW_lim3は「第3所定回数」の一例である。 Further, when the count frequency ct exceeds the switching frequency first upper limit value SW_lim1 or exceeds the switching frequency third upper limit SW_lim3, the carrier frequency switching unit 240 determines that the absolute value of the AC system effective voltage Vd falls within the predetermined range. Even if it exceeds, the first frequency fc1 is selected as the carrier command frequency fc *. In this case, the switching number first upper limit value SW_lim1 or the switching number third upper limit SW_lim3 is an example of the “third predetermined number”.
[変形例1のまとめ]
 以上説明したように、変形例1の電力変換装置1は、第1パルス切替指令SW1、及び第2パルス切替指令SW2の有効回数に制限を設けることにより、電力変換損失に伴う総発熱量が増加することを抑制し、電力変換装置1が発熱による故障で長時間運転停止することを抑制することができる。また、変形例1の電力変換装置1によれば、電力変換装置1に連系される系統の系統事故、或いは外部システムから外部指令SYSによって報知される系統の系統事故が短時間に頻発する場合であっても、電力変換に係る電力損失を低減しつつ、総発熱量が許容を超えない範囲で系統事故時の運転継続性を向上させることができる。
[Summary of Modification 1]
As described above, the power conversion device 1 of the first modification increases the total heat generation amount due to the power conversion loss by limiting the number of effective times of the first pulse switching command SW1 and the second pulse switching command SW2. It is possible to prevent the power converter 1 from stopping for a long time due to a failure due to heat generation. In addition, according to the power conversion device 1 of the first modification, when a system fault of the system connected to the power conversion device 1 or a system fault of the system notified by the external command SYS from the external system frequently occurs in a short time. Even in this case, it is possible to reduce the power loss related to the power conversion and improve the operation continuity at the time of a system fault within the range in which the total calorific value does not exceed the allowable value.
(変形例2)
 以下、図面を参照して変形例2のキャリア周波数切替指令部230bについて説明する。変形例1のキャリア周波数切替指令部230aでは、更に、交流系統有効電圧Vdが電圧上限値Vth_Hから電圧下限値Vth_Lによって示される範囲を逸脱した状態の回数(以下、カウント回数ct)に基づいて、第1パルス切替指令SW1と、第2パルス切替指令SW2とを出力する場合について説明した。変形例2のキャリア周波数切替指令部230bでは、更に、カウント回数ctに基づいて、電力変換器10の運転を停止させる場合について説明する。なお、上述した実施形態、及び変形例と同様の構成については、同一の符号を付して説明を省略する。
(Modification 2)
Hereinafter, with reference to the drawings, the carrier frequency switching command unit 230b of Modification 2 will be described. In the carrier frequency switching command unit 230a of Modification Example 1, further, based on the number of times (hereinafter, the number of counts ct) that the AC system effective voltage Vd deviates from the range indicated by the voltage upper limit value Vth_H and the voltage lower limit value Vth_L, The case where the first pulse switching command SW1 and the second pulse switching command SW2 are output has been described. In the carrier frequency switching command unit 230b of the second modification, a case where the operation of the power converter 10 is stopped based on the count number ct will be further described. In addition, about the structure similar to embodiment and the modification mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.
 図13は、変形例2のキャリア周波数切替指令部230bの処理を概念的に示す図である。変形例2のキャリア周波数切替指令部230bは、キャリア周波数切替指令部230bが備える各機能部に加えて、第4比較器238を更に備える。第4比較器238は、回数カウンタ235によって出力されたカウント回数ctと、切替回数第3上限SW_lim3とを比較する。第4比較器238は、カウント回数ctが切替回数第3上限SW_lim3を上回っている場合、ゲート信号生成部300に停止指令信号STPを出力する。ゲート信号生成部300は、第4比較器238によって停止指令信号STPが出力された場合、電力変換器10が電力変換を停止するようなゲート信号(例えば、(gtp、gtn)=(0、0))を生成し、出力する。 FIG. 13 is a diagram conceptually showing the process of the carrier frequency switching command unit 230b of the second modification. The carrier frequency switching command unit 230b of Modification 2 further includes a fourth comparator 238 in addition to the functional units included in the carrier frequency switching command unit 230b. The fourth comparator 238 compares the count number ct output by the number counter 235 with the switching number third upper limit SW_lim3. The fourth comparator 238 outputs the stop command signal STP to the gate signal generation unit 300 when the count number ct exceeds the switching number third upper limit SW_lim3. The gate signal generation unit 300, when the stop command signal STP is output by the fourth comparator 238, a gate signal that causes the power converter 10 to stop power conversion (for example, (gtp, gtn) = (0, 0 )) Is generated and output.
 なお、切替回数第3上限SW_lim3は、切替回数第1上限値SW_lim1、及び切替回数第2上限値SW_lim2と比して十分に大きい値である。また、切替回数第3上限SW_lim3は、回数に代えて(或いは、加えて)、時間(期間)によって示されてもよい。この場合、上限値は、電力変換器10を高周波域のキャリア指令周波数fc*(例えば、第2周波数fc2、又は第3周波数fc3)によって制御可能な時間(期間)を示す値である。切替回数第3上限SW_lim3は、「第4所定回数」の一例である。 The switching number third upper limit SW_lim3 is a value sufficiently larger than the switching number first upper limit value SW_lim1 and the switching number second upper limit value SW_lim2. Further, the switching upper limit third upper limit SW_lim3 may be indicated by time (period) instead of (or in addition to) the number of times. In this case, the upper limit value is a value indicating a time (period) during which the power converter 10 can be controlled by the carrier command frequency fc * (for example, the second frequency fc2 or the third frequency fc3) in the high frequency range. The switching count third upper limit SW_lim3 is an example of a “fourth predetermined count”.
[変形例2のまとめ]
 以上説明したように、変形例2の電力変換装置1は、カウントの回数(つまり、ある設定時間内での系統電圧異常状態の回数)が切替回数第3上限SW_lim3を上回った場合、電力変換器10の電力変換を停止させる。ここで、系統電圧異常状態の回数が多い場合とは、連系される系統、或いは外部システムから外部指令SYSによって報知されるの系統の状態が不安定な場合である。また、系統の状態が不安定な場合において電力変換装置1が電力変換を継続すると、コンデンサ電圧Vcが過電圧レベルに達する場合があり、この場合、電力変換器10は、動作を停止させ、コンデンサ電圧Vcを通常レベルまで放電させないと運転再開できない。変形例2の電力変換装置1は、系統電圧異常信号ERRの回数によって電力変換器10を停止させることにより、電力損失を低減しつつ、系統事故時の運転再開を高速化し、運転継続性を向上させることができる。
[Summary of Modification 2]
As described above, in the power conversion device 1 of the modified example 2, when the number of counts (that is, the number of system voltage abnormal states within a certain set time) exceeds the switching count third upper limit SW_lim3, the power converter. The power conversion of 10 is stopped. Here, the case where the number of abnormalities in the system voltage is large is a case where the state of the system to be interconnected or the system informed by the external command SYS from the external system is unstable. Further, when the power conversion device 1 continues the power conversion when the system state is unstable, the capacitor voltage Vc may reach the overvoltage level. In this case, the power converter 10 stops the operation and the capacitor voltage The operation cannot be resumed unless Vc is discharged to the normal level. The power conversion device 1 of the modified example 2 stops the power converter 10 according to the number of the system voltage abnormality signal ERR, thereby reducing power loss, speeding up the operation restart at the time of a system failure, and improving the operation continuity. Can be made.
(変形例3)
 以下、図面を参照して変形例3の変換器制御装置20aについて説明する。実施形態の変換器制御装置20において、電圧指令値演算部220は、電力変換器10の出力する有効電力PEと、無効電力QEとが、予め定められた有効電力指令値PE*と、無効電力指令値QE*とになるように、各セルCLのセル電圧Vclを指示するセル電圧指令値Vcl*を算出する場合について説明した。変形例3の変換器制御装置20aにおいて、電圧指令値演算部220は、第1パルス切替指令SW1の有無に基づいて、有効電力指令値PE*と、無効電力指令値QE*とに制限を設る場合について説明する。なお、上述した実施形態、及び変形例と同様の構成については、同一の符号を付して説明を省略する。
(Modification 3)
Hereinafter, the converter control device 20a of the third modification will be described with reference to the drawings. In the converter control device 20 of the embodiment, the voltage command value calculation unit 220 determines that the active power PE output by the power converter 10 and the reactive power QE have a predetermined active power command value PE * and reactive power. The case has been described in which the cell voltage command value Vcl * for instructing the cell voltage Vcl of each cell CL is calculated so as to be the command value QE *. In the converter control device 20a according to the modification 3, the voltage command value calculation unit 220 sets limits on the active power command value PE * and the reactive power command value QE * based on the presence / absence of the first pulse switching command SW1. The case will be described. In addition, about the structure similar to embodiment and the modification mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.
 図14は、変形例3の変換器制御装置20aの構成の一例を示す図である。変形例3の変換器制御装置20aは、変換器制御装置20が備える構成に代えて(或いは、加えて)、電圧指令値演算部220と、キャリア周波数切替指令部230と、キャリア周波数切替部240と、三角波キャリア生成部250と、変換器260とを機能部として備える。変換器260は、キャリア周波数切替指令部230によって第1パルス切替指令SW1が出力されている場合、予め定められる有効電力指令値PE*、及び無効電力指令値QE*を制限する。変換器260は、例えば、第1パルス切替指令SW1が出力されている場合、有効電力指令値PE*を、有効電力上限指令値+P*_limから、有効電力下限指令値-P*_limの範囲に制限し、無効電力指令値QE*を、無効電力上限指令値+Q*_limから、無効電力下限指令値-Q*_limの範囲に制限する。ここで、P*_limの値は、電力変換器10の定格有効電力未満の値であり、Q*_limの値は、電力変換器10の定格無効電力未満の値である。 FIG. 14 is a diagram illustrating an example of the configuration of the converter control device 20a according to the third modification. Instead of (or in addition to) the configuration included in the converter control device 20, the converter control device 20a according to the modification 3 has a voltage command value calculation unit 220, a carrier frequency switching command unit 230, and a carrier frequency switching unit 240. The triangular wave carrier generation unit 250 and the converter 260 are provided as functional units. The converter 260 limits the predetermined active power command value PE * and reactive power command value QE * when the first pulse switching command SW1 is output by the carrier frequency switching command unit 230. For example, when the first pulse switching command SW1 is output, the converter 260 changes the active power command value PE * from the active power upper limit command value + P * _lim to the active power lower limit command value −P * _lim. The reactive power command value QE * is limited to a range from the reactive power upper limit command value + Q * _lim to the reactive power lower limit command value −Q * _lim. Here, the value of P * _lim is less than the rated active power of the power converter 10, and the value of Q * _lim is less than the rated reactive power of the power converter 10.
 電圧指令値演算部220は、変換器260によって制限された有効電力指令値PE*、及び無効電力指令値QE*に基づいて、セル電圧指令値Vcl*を算出するため、ゲート信号生成部300は、結果的に電力変換器10の有効電力PEと無効電力QEに比例する電力損失を抑えるようなゲート信号を生成することができる。 The voltage command value calculation unit 220 calculates the cell voltage command value Vcl * based on the active power command value PE * and the reactive power command value QE * limited by the converter 260. As a result, it is possible to generate a gate signal that suppresses power loss proportional to the active power PE and the reactive power QE of the power converter 10.
[変形例3のまとめ]
 以上説明したように、変形例3の電力変換装置1は、第1パルス切替指令SW1が出力され、電力変換器10が高周波域のキャリア指令周波数fc*(例えば、第2周波数fc2、又は第3周波数fc3)によってスイッチング制御される状態において、電力変換器10の電力損失を低減させることができる。
[Summary of Modification 3]
As described above, in the power conversion device 1 of the modified example 3, the first pulse switching command SW1 is output, and the power converter 10 outputs the carrier command frequency fc * in the high frequency range (for example, the second frequency fc2 or the third frequency fc2). The power loss of the power converter 10 can be reduced in the state where the switching is controlled by the frequency fc3).
(変形例4)
 以下、図面を参照して変形例4の電力変換装置1について説明する。上述した実施形態、及び変形例では、変換器制御装置20のキャリア周波数切替指令部230は、電力変換装置1の保護装置等の外部システムから出力される外部指令SYSに基づいて、キャリア指令周波数fc*としての周波数を選択する場合について説明した。変形例4の電力変換装置1では、電力変換装置1に連系される系統ののうち、直流側に接続される他の電力変換装置1から出力される信号に基づいて、キャリア指令周波数fc*としての周波数を選択する場合について説明する。なお、上述した実施形態、及び変形例と同様の構成については、同一の符号を付して説明を省略する。
(Modification 4)
Hereinafter, the power converter 1 of the modification 4 is demonstrated with reference to drawings. In the above-described embodiment and modification, the carrier frequency switching command unit 230 of the converter control device 20 is based on the external command SYS output from the external system such as the protection device of the power conversion device 1 and the carrier command frequency fc. The case of selecting the frequency as * has been described. In the power conversion device 1 of the modification 4, the carrier command frequency fc * is based on the signal output from another power conversion device 1 connected to the DC side in the system connected to the power conversion device 1. A case of selecting the frequency as will be described. In addition, about the structure similar to embodiment and the modification mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.
 図15は、変形例4における電力変換装置1の使用環境の一例を示す図である。変形例4において、直流系統の一端と、他端とには、それぞれ電力変換装置1αと、電力変換装置1βとが対向して接続される。電力変換装置1αは第1交流系統と、直流系統との連系点に設けられ、第1交流系統が供給する交流電力と、直流系統が供給する直流電力とを相互に変換する。電力変換装置1βは、第2交流系統と、直流系統との連系点に設けられ、第2交流系統が供給する交流電力と、直流系統が供給する直流電力とを相互に変換する。 15: is a figure which shows an example of the usage environment of the power converter device 1 in the modification 4. As shown in FIG. In the modified example 4, the power conversion device 1α and the power conversion device 1β are connected to one end and the other end of the DC system so as to face each other. The power converter 1α is provided at a connection point between the first AC system and the DC system, and mutually converts the AC power supplied by the first AC system and the DC power supplied by the DC system. The power converter 1β is provided at a connection point between the second AC system and the DC system, and mutually converts the AC power supplied by the second AC system and the DC power supplied by the DC system.
 変形例4において、第1パルス出力部233は、第1パルス切替指令SW1をキャリア周波数切替部240、及び他の電力変換装置1に出力する。また、変形例4において、キャリア周波数切替指令部230は、他の電力変換装置1によって出力された第1パルス切替指令SW1を、外部指令SYSとして取得する。 In Modification 4, the first pulse output unit 233 outputs the first pulse switching command SW1 to the carrier frequency switching unit 240 and the other power conversion device 1. Moreover, in the modified example 4, the carrier frequency switching command unit 230 acquires the first pulse switching command SW1 output by another power conversion device 1 as the external command SYS.
 なお、上述した一例では、2つの電力変換装置1が直流系統の一端と、他端とに接続される場合について説明したが、これに限られない。電力変換装置1は、例えば、2以上の複数の電力変換装置1と直流系統を介して接続されてもよい。 In the above example, the case where the two power conversion devices 1 are connected to one end and the other end of the DC system has been described, but the present invention is not limited to this. The power conversion device 1 may be connected to, for example, two or more power conversion devices 1 via a DC system.
[変形例4のまとめ]
 以上説明したように、変形例4の電力変換装置1は、他の電力変換装置1から取得した外部指令SYSに基づいて、キャリア指令周波数fc*を選択し、対向の他の電力変換装置1が検知した交流系統事故によって自装置および自装置に連系される系統が受ける影響を早急に収束することができる。したがって、変形例4の電力変換装置1は、電力損失を低減しつつ、系統事故時の運転継続性を向上させることができる。
[Summary of Modification 4]
As described above, the power conversion device 1 of the modified example 4 selects the carrier command frequency fc * based on the external command SYS acquired from the other power conversion device 1, and the other power conversion device 1 in the opposite direction selects the carrier command frequency fc *. The influence of the detected AC system fault on the self-device and the system connected to the self-device can be quickly settled. Therefore, the power conversion device 1 of Modification 4 can improve the operation continuity at the time of a system fault while reducing the power loss.
 本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれると同様に、特許請求の範囲に記載された発明とその均等の範囲に含まれるものである。 Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the invention described in the claims and the equivalents thereof as well as included in the scope and the gist of the invention.

Claims (15)

  1.  直流と交流とを相互に変換可能な電力変換装置であって、
     互いに並列に接続されるコンデンサとスイッチング素子とを含む単位変換器が少なくとも1つ以上直列に接続されたアームユニットと、
     前記交流の周波数に第1非整数値を乗じた第1周波数と、前記交流の周波数に前記第1非整数値以上の第2非整数値を乗じた第2周波数と、前記第2周波数より高い周波数である第3周波数とのうち、いずれかの周波数の三角波キャリア信号を選択的に生成する生成部と、
     前記生成部によって生成された前記三角波キャリア信号に基づいて、前記スイッチング素子を制御する制御部と、
     前記生成部に、いずれの周波数の前記三角波キャリア信号を生成させるかを切り替える切替部と、を備え、
     前記切替部は、前記生成部に、
     前記交流の電圧の絶対値が所定範囲にある場合、前記第1周波数の三角波キャリア信号を生成させ、
     前記交流の電圧の絶対値が前記所定範囲にない場合、前記第3周波数の三角波キャリア信号を第1の期間の間、生成させ、
     前記交流の電圧の絶対値が前記所定範囲になく、且つ前記生成部が前記第3周波数の三角波キャリア信号を生成していない場合、前記第2周波数の三角波キャリア信号を第2の期間の間、生成させる、
     電力変換装置。
    A power conversion device capable of mutually converting DC and AC,
    An arm unit in which at least one unit converter including a capacitor and a switching element connected in parallel to each other is connected in series;
    A first frequency obtained by multiplying the frequency of the alternating current by a first non-integer value, a second frequency obtained by multiplying the frequency of the alternating current by a second non-integer value equal to or greater than the first non-integer value, and higher than the second frequency. A generator for selectively generating a triangular wave carrier signal having any one of the third frequencies, which is the frequency,
    A control unit for controlling the switching element based on the triangular wave carrier signal generated by the generation unit,
    The generation unit, a switching unit for switching which frequency of the triangular wave carrier signal is generated, and,
    The switching unit, in the generation unit,
    When the absolute value of the AC voltage is within a predetermined range, the triangular wave carrier signal of the first frequency is generated,
    When the absolute value of the alternating voltage is not within the predetermined range, the triangular wave carrier signal of the third frequency is generated during the first period,
    When the absolute value of the AC voltage is not within the predetermined range and the generator does not generate the triangular wave carrier signal of the third frequency, the triangular wave carrier signal of the second frequency is generated during the second period. Generate,
    Power converter.
  2.  前記切替部は、前記交流の電圧の絶対値が所定範囲にある場合において、他の装置から指令信号を取得した場合、前記第2周波数の三角波キャリア信号を前記第2の期間の間、生成させる、
     請求項1に記載の電力変換装置。
    When the command value is obtained from another device when the absolute value of the AC voltage is within a predetermined range, the switching unit causes the triangular wave carrier signal of the second frequency to be generated during the second period. ,
    The power conversion device according to claim 1.
  3.  前記第2の期間は、前記第1の期間よりも長い期間である、
     請求項1又は請求項2に記載の電力変換装置。
    The second period is longer than the first period,
    The power conversion device according to claim 1 or 2.
  4.  前記第3周波数は、前記交流の周波数に前記第2非整数値以上の第3非整数値を乗じた周波数である、
     請求項1から請求項3のうちいずれか一項に記載の電力変換装置。
    The third frequency is a frequency obtained by multiplying the frequency of the alternating current by a third non-integer value equal to or higher than the second non-integer value.
    The power conversion device according to any one of claims 1 to 3.
  5.  前記第3周波数は、前記交流の周波数に前記第2非整数値以上の整数値を乗じた周波数であり、前記整数値は、4以上である、
     請求項1から請求項3のうちいずれか一項に記載の電力変換装置。
    The third frequency is a frequency obtained by multiplying the frequency of the alternating current by an integer value of the second non-integer value or more, and the integer value is 4 or more,
    The power conversion device according to any one of claims 1 to 3.
  6.  前記第3周波数は、予め定められた固定周波数である、
     請求項1から請求項3のうちいずれか一項に記載の電力変換装置。
    The third frequency is a predetermined fixed frequency,
    The power conversion device according to any one of claims 1 to 3.
  7.  前記生成部は、所定時間内において、前記交流の電圧の絶対値が前記所定範囲を超えた状態の回数が第1所定回数以上である場合、前記第3周波数の三角波キャリア信号を生成しない、
     請求項1から請求項6のうちいずれか一項に記載の電力変換装置。
    The generation unit does not generate the triangular wave carrier signal having the third frequency when the number of times the absolute value of the AC voltage exceeds the predetermined range is a first predetermined number or more within a predetermined time,
    The power conversion device according to any one of claims 1 to 6.
  8.  前記生成部は、所定時間内において、前記交流の電圧の絶対値が前記所定範囲を超えた状態の回数が第2所定回数以上である場合、前記第2周波数の三角波キャリア信号を生成しない、
     請求項1から請求項7のうちいずれか一項に記載の電力変換装置。
    The generating unit does not generate the triangular wave carrier signal having the second frequency when the number of times the absolute value of the AC voltage exceeds the predetermined range is a second predetermined number or more within a predetermined time.
    The power conversion device according to any one of claims 1 to 7.
  9.  前記生成部は、所定時間内において、前記交流の電圧の絶対値が前記所定範囲を超えた状態の回数が第3所定回数以上である場合、前記交流の電圧の絶対値が前記所定範囲を超えても前記第1周波数の三角波キャリア信号を生成し続ける、
     請求項1から請求項8のうちいずれか一項に記載の電力変換装置。
    If the number of times that the absolute value of the AC voltage exceeds the predetermined range is a third predetermined number of times or more within a predetermined time, the generation unit causes the absolute value of the AC voltage to exceed the predetermined range. Even if the triangular wave carrier signal of the first frequency is continuously generated,
    The power conversion device according to any one of claims 1 to 8.
  10.  前記生成部は、所定時間内において、前記交流の電圧の絶対値が前記所定範囲を超えた状態の回数が第4所定回数以上である場合、
     前記制御部は、前記スイッチング素子の動作を停止させる、
     請求項1から請求項9のうちいずれか一項に記載の電力変換装置。
    If the number of times the absolute value of the AC voltage exceeds the predetermined range is a fourth predetermined number or more within a predetermined time,
    The control unit stops the operation of the switching element,
    The power conversion device according to any one of claims 1 to 9.
  11.  前記制御部は、前記生成部によって前記第2周波数または前記第3周波数の三角波キャリア信号が生成されている場合、前記アームユニットを流れる電流が所定の電流値未満になるように、前記スイッチング素子を制御する、
     請求項1から請求項10のうちいずれか一項に記載の電力変換装置。
    The control unit controls the switching element so that the current flowing through the arm unit becomes less than a predetermined current value when the triangular wave carrier signal of the second frequency or the third frequency is generated by the generation unit. Control,
    The power conversion device according to any one of claims 1 to 10.
  12.  前記生成部は、自装置の直流側に接続される他の交直変換装置からの指令信号に基づいて、前記第2周波数の三角波キャリア信号を前記第2の期間の間、生成させ、
     前記指令信号は、前記他の交直変換装置の交流側で系統電圧異常が生じたことに伴い出力される信号である、
     請求項1から請求項11のいずれか一項に記載の電力変換装置。
    The generator generates a triangular wave carrier signal of the second frequency during the second period based on a command signal from another AC / DC converter connected to the DC side of the own device,
    The command signal is a signal output when a system voltage abnormality occurs on the AC side of the other AC-DC converter.
    The power conversion device according to any one of claims 1 to 11.
  13.  請求項1から請求項11のいずれかに記載の電力変換装置を二つ以上備え、前記二つ以上の電力変換装置の直流側が互いに接続されて構成される電力変換システムであって、
     前記生成部は、自装置の直流側に接続される他の交直変換装置からの指令信号に基づいて、前記第2周波数の三角波キャリア信号を前記第2の期間の間、生成させ、
     前記指令信号は、前記交直変換装置の交流側で系統電圧異常が生じたことに伴い出力される信号である、
     電力変換システム。
    A power conversion system comprising two or more power conversion devices according to any one of claims 1 to 11, wherein direct current sides of the two or more power conversion devices are connected to each other.
    The generator generates a triangular wave carrier signal of the second frequency during the second period based on a command signal from another AC / DC converter connected to the DC side of the own device,
    The command signal is a signal that is output when a system voltage abnormality occurs on the AC side of the AC / DC converter,
    Power conversion system.
  14.  直流と交流とを相互に変換可能であり、互いに並列に接続されるコンデンサとスイッチング素子とを含む単位変換器が少なくとも1つ以上直列に接続されたアームユニットを備える電力変換装置が、
     前記交流の周波数に第1非整数値を乗じた第1周波数と、前記交流の周波数に前記第1非整数値以上の第2非整数値を乗じた第2周波数と、前記第2周波数より高い周波数である第3周波数とのうち、いずれかの周波数の三角波キャリア信号を選択的に生成し、
     生成された前記三角波キャリア信号に基づいて、前記スイッチング素子を制御し、
     いずれの周波数の前記三角波キャリア信号を生成させるかを切り替えることにより、
     前記交流の電圧の絶対値が所定範囲にある場合、前記第1周波数の三角波キャリア信号を生成させ、
     前記交流の電圧の絶対値が前記所定範囲にない場合、前記第3周波数の三角波キャリア信号を第1の期間の間、生成させ、
     前記交流の電圧の絶対値が前記所定範囲になく、且つ前記第3周波数の三角波キャリア信号を生成していない場合、前記第2周波数の三角波キャリア信号を第2の期間の間、生成させる、
     電力変換方法。
    A power converter including an arm unit in which at least one unit converter including a capacitor and a switching element, which are capable of mutually converting direct current and alternating current and are connected in parallel, are connected in series,
    A first frequency obtained by multiplying the frequency of the alternating current by a first non-integer value, a second frequency obtained by multiplying the frequency of the alternating current by a second non-integer value equal to or greater than the first non-integer value, and higher than the second frequency. Selectively generate a triangular wave carrier signal of any one of the third frequency, which is the frequency,
    Controlling the switching element based on the generated triangular wave carrier signal,
    By switching which frequency the triangular wave carrier signal is generated,
    When the absolute value of the AC voltage is within a predetermined range, the triangular wave carrier signal of the first frequency is generated,
    When the absolute value of the alternating voltage is not within the predetermined range, the triangular wave carrier signal of the third frequency is generated during the first period,
    When the absolute value of the AC voltage is not within the predetermined range and the triangular wave carrier signal of the third frequency is not generated, the triangular wave carrier signal of the second frequency is generated for the second period,
    Power conversion method.
  15.  直流と交流とを相互に変換可能であり、互いに並列に接続されるコンデンサとスイッチング素子とを含む単位変換器が少なくとも1つ以上直列に接続されたアームユニットを備える電力変換装置に、
     前記交流の周波数に第1非整数値を乗じた第1周波数と、前記交流の周波数に前記第1非整数値以上の第2非整数値を乗じた第2周波数と、前記第2周波数より高い周波数である第3周波数とのうち、いずれかの周波数の三角波キャリア信号を選択的に生成させ、
     生成された前記三角波キャリア信号に基づいて、前記スイッチング素子を制御させ、
     いずれの周波数の前記三角波キャリア信号を生成させるかを切り替えさせることにより、
     前記交流の電圧の絶対値が所定範囲にある場合、前記第1周波数の三角波キャリア信号を生成させ、
     前記交流の電圧の絶対値が前記所定範囲にない場合、前記第3周波数の三角波キャリア信号を第1の期間の間、生成させ、
     前記交流の電圧の絶対値が前記所定範囲になく、前記第3周波数の三角波キャリア信号を生成していない場合、前記第2周波数の三角波キャリア信号を第2の期間の間、生成させる、
     プログラム。
    A power conversion device including an arm unit in which at least one unit converter including a capacitor and a switching element, which are capable of mutually converting direct current and alternating current and are connected in parallel to each other, are connected in series,
    A first frequency obtained by multiplying the frequency of the alternating current by a first non-integer value, a second frequency obtained by multiplying the frequency of the alternating current by a second non-integer value equal to or greater than the first non-integer value, and higher than the second frequency. Selectively generate a triangular wave carrier signal of any one of the third frequency, which is the frequency,
    Based on the generated triangular wave carrier signal, to control the switching element,
    By switching which frequency the triangular wave carrier signal is generated,
    When the absolute value of the AC voltage is within a predetermined range, the triangular wave carrier signal of the first frequency is generated,
    When the absolute value of the alternating voltage is not within the predetermined range, the triangular wave carrier signal of the third frequency is generated during the first period,
    When the absolute value of the AC voltage is not within the predetermined range and the triangular wave carrier signal of the third frequency is not generated, the triangular wave carrier signal of the second frequency is generated for the second period.
    program.
PCT/JP2018/038886 2018-10-18 2018-10-18 Power conversion device, power conversion system, power conversion method, and program WO2020079817A1 (en)

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