JP6366339B2 - Inverter - Google Patents

Description

  The present invention relates to a power conditioner connected between a power source and a system power source, and more particularly to a power conditioner having an isolated operation preventing function.

  In recent years, interest in protection of the global environment has increased, and a distributed power supply system including a power generation device using a solar cell or a fuel cell and a storage battery such as a lithium ion battery has been put into practical use. The DC power output from these distributed power sources is converted into AC power corresponding to the frequency and voltage of a single-phase three-wire system power source by an electric power company by a power conditioner. In addition, as an operation method, the system is connected to the system power supply, not operated independently from the system power supply.

  In such a grid-connected system, when the power supply of the grid power supply is stopped due to construction, inspection, accident, etc. (during a grid power failure), the distributed power supply and inverter are operated while being linked to the grid power supply. In the single operation state, a reverse power flow caused by a reverse voltage flows into the system power source in the power outage state, which may threaten the safety on the system power source side. Therefore, it is necessary to reliably detect the single operation state of the customer side equipment and stop the inverter.

  For example, Japanese Patent Laid-Open No. 2000-236671 (Patent Document 1) discloses a grid-connected power generation device. The grid-connected power generation device is a detection unit that detects the frequency of the system power source, and compares the frequency of the system power source detected by the detection unit with the frequency of the output power output from the inverter to determine whether they match. And when the frequency of the output power is set to be different from the frequency of the system power supply, it is predetermined in the same direction as the frequency change direction of the output power set last time when it is determined by the comparison means to match. A setting means for setting a frequency so as to change only by a value, and a power failure detection means for detecting whether or not a power failure has occurred in the system power supply based on the setting result of the setting means or the frequency of the system power supply and output power .

JP 2000-236671 A

  However, in the technique disclosed in Patent Document 1, no consideration is given to a case where it is connected to a single-phase three-wire system power supply. In particular, when connected to a single-phase three-wire system power supply, the current value output from the inverter is different for each of the three wires. Have difficulty.

  The present invention has been made to solve the above-described problems, and in a power conditioner linked to a single-phase three-wire system power supply, more accurately detects an independent operation state of an inverter. Thus, an object of the present invention is to provide a power conditioner that can reliably prevent isolated operation.

  According to an embodiment, a power conditioner connected between a DC power source and a system power source is provided. The power conditioner converts a direct current power of a direct current power source into a single phase alternating current power and outputs the inverter, a first power line including a first voltage line and a neutral line, a second voltage line and a medium A power supply line that supplies output power from the inverter, and a first voltage frequency that detects a first voltage frequency of the voltage between the first voltage line and the neutral line. 1 detection means, a second detection means for detecting a second voltage frequency of the voltage between the second voltage line and the neutral line, and a control means for controlling the inverter. The control means sets the first current frequency of the current output to the first power line so as to be different from the first voltage frequency, and sets the first current frequency output to the second power line so as to be different from the second voltage frequency. Whether or not the inverter is in an isolated operation state based on setting means for setting the current frequency of 2, at least one of the first voltage frequency and the second voltage frequency, and a reference range of a predetermined voltage frequency It includes determination means for determining, and stop means for stopping the inverter when the inverter is in the single operation state.

  According to the present invention, in a power conditioner linked to a single-phase three-wire system power supply, it is possible to reliably prevent an isolated operation by detecting the isolated operation state of the inverter with higher accuracy.

It is a figure which shows schematically the whole structure of the electric power supply system with which the power conditioner according to Embodiment 1 is applied. FIG. 3 is a schematic diagram showing a configuration of a control unit according to the first embodiment. 6 is a flowchart showing a current frequency shift setting process executed by a control unit according to the first embodiment. It is a flowchart which shows the acceleration shift process which the control part according to Embodiment 1 performs. It is a flowchart which shows the process at the time of the control part according to Embodiment 1 stopping an inverter. FIG. 7 is a schematic diagram showing a configuration of a control unit according to a second embodiment. 6 is a flowchart showing a processing procedure of a control unit according to the second embodiment. It is a figure which shows roughly the whole structure of the electric power supply system with which the power conditioner according to Embodiment 3 is applied. FIG. 12 is a schematic diagram showing a configuration of a control unit according to a third embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Embodiment 1]
<Overall configuration>
FIG. 1 is a diagram schematically showing an overall configuration of a power supply system to which a power conditioner according to the first embodiment is applied.

  Referring to FIG. 1, the power supply system includes a power conditioner 2, a storage battery 4, loads 5A, 5B, and 5C (hereinafter also collectively referred to as “load 5”), current sensors 61 and 62, and a system power supply. 8 and so on. A part of the power supply system is installed in a house such as a house or an office, for example.

  The system power supply 8 is a single-phase three-wire commercial AC power system, and supplies power to the home via the power line 3.

  The power line 3 includes a voltage line U, a voltage line W, and a neutral line O. The power line 3 is wired in the house through a distribution board (not shown), and is connected between any two of the grounded neutral line O and the voltage lines U and W on both sides. Power is supplied to the loaded load 5. Specifically, the load 5A is connected between the voltage line U and the neutral line O, the load 5B is connected between the voltage line W and the neutral line O, and the load 5C is connected between the voltage line U and the voltage line W. Has been. The voltage between the voltage line U and the neutral line O (between the U and O phases) and the voltage between the voltage line W and the neutral line O (between the W and O phases) are AC (alternating current) 100V, and during this time, AC 100V Electrical equipment is connected. The voltage between the voltage line U and the voltage line W (between the U and W phases) is AC200V, and an electric device for AC200V is connected between them.

  Specifically, an AC100V electrical device includes a power line composed of a voltage line U and a neutral line O (hereinafter also referred to as “U-phase power line”), or a voltage line W and a neutral line O. Power is supplied from a configured power line (hereinafter also referred to as “W-phase power line”). Moreover, since the AC200V electric device is connected to the voltage line U and the voltage line W, power is supplied to the electric device via the U-phase power line and the W-phase power line.

  The load 5 is composed of, for example, a single or a plurality of electric devices. The electric device is, for example, an AC 100 V fan, a vacuum cleaner, a refrigerator, or an AC 200 V air conditioner. Note that the electrical device is not limited to this, and may be a television, a personal computer, a microwave oven, or the like.

  The power conditioner 2 converts DC power output from the storage battery 4 into AC power, and supplies the AC power to the load 5 through the power line 3. The detailed configuration of the power conditioner 2 will be described later.

  The storage battery 4 is a chargeable / dischargeable power storage element. The type of the storage battery 4 is not particularly limited, and is constituted by a secondary battery such as a lithium ion battery, a lead storage battery, a Nas battery, or a nickel metal hydride battery.

  Storage battery 4 is an example of a “DC power supply” according to the first embodiment (and all embodiments described later). The DC power source is not particularly limited to the storage battery 4 as long as it is a power source that supplies DC power. The DC power supply according to the first embodiment is not particularly limited as long as it generates DC power, such as a solar cell, a fuel cell, a wind power generator, an electric vehicle, a plasma generator, and a capacitor. The DC power supply may be a combination of these.

  The power line 3 is provided with current sensors 61 and 62 for detecting a current (power receiving current) flowing through a power receiving point P that receives AC power from the system power supply 8. Specifically, the current sensor 61 is provided at the power receiving point P of the voltage line U, and the current sensor 62 is provided at the power receiving point P of the voltage line W.

  Current sensors 61 and 62 detect received currents Iup and Iwp, respectively, and output the detected values to power conditioner 2. In the present embodiment, each of current sensors 61 and 62 detects a received current from system power supply 8 as a positive value received current, and detects a reverse flow current to system power supply 8 as a negative value received current.

<Configuration of inverter 2>
Referring to FIG. 1, power conditioner 2 includes power line 3, control unit 10, inverter 20, reactors 31 to 33, current sensors 41 and 42, voltage sensors 51 and 52, and DC bus 150. including.

  In the present embodiment, the storage battery 4 is employed as a DC power source connected to the power conditioner 2. In Japan, in consideration of the influence on the system power supply 8, it is not permitted to reversely flow the discharge power from the storage battery or the fuel cell to the system power supply side. Therefore, the power conditioner according to the present embodiment 2 performs reverse power flow prevention control for preventing reverse power flow from the storage battery 4 to the system power supply 8.

  The DC bus 150 is a power line for transmitting DC power supplied from the storage battery 4 to the inverter 20. DC bus 150 includes a positive bus PL and a negative bus SL, which are power line pairs.

  The inverter 20 converts the DC power supplied from the storage battery 4 via the DC bus 150 into AC power in accordance with the switching control signals S1 to S6 from the control unit 10, and the AC power obtained by the conversion is converted into a power line. 3 is output. Inverter 20 includes transistors Q1 to Q6, which are switching elements, and diodes D1 to D6. Transistors Q1 and Q2 are connected in series between positive bus PL and negative bus SL forming DC bus 150. An intermediate point between transistor Q1 and transistor Q2 is connected to voltage line U which is a U-phase line. Reactor 31 is provided on voltage line U.

  Transistors Q3 and Q4 are connected in series between positive bus PL and negative bus SL. An intermediate point between transistors Q3 and Q4 is connected to neutral line O, which is an O-phase line. Reactor 32 is provided on neutral line O.

  Transistors Q5 and Q6 are connected in series between positive bus PL and negative bus SL. An intermediate point between transistors Q5 and Q6 is connected to voltage line W which is a W-phase line. Reactor 33 is provided on voltage line W.

As the transistors Q1 to Q6, for example, an IGBT (Insulated Gate Bipolar)
Transistor) can be used. Alternatively, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) may be used.

  Transistors Q1-Q6 are turned on / off in response to switching control signals S1-S6 from control unit 10, respectively. The DC power supplied from the storage battery 4 can be converted into single-phase AC power by turning on / off the transistors Q1 to Q6 at a predetermined timing.

  The current sensor 41 is provided on the voltage line U, detects the current Iu flowing through the voltage line U, and outputs the detection result to the control unit 10. The current sensor 42 is provided on the voltage line W, measures the current Iw flowing through the voltage line W, and outputs the detection result to the control unit 10.

  The voltage sensor 51 is connected between the voltage line U and the neutral line O, detects the voltage Vu between the U-O phases, and outputs the detection result to the control unit 10. The detection result of the voltage sensor 51 includes the voltage value and frequency of the voltage Vu between the U and O phases. The voltage sensor 52 is connected between the voltage line W and the neutral line O, detects the voltage Vw between the W-O phases, and outputs the detection result to the control unit 10. The detection result of the voltage sensor 52 includes the voltage value and the frequency of the voltage Vw between the W-O phases.

  The control unit 10 controls the power supplied from the power conditioner 2 to the load 5. The control unit 10 may have a hardware configuration such as a circuit, or may include a CPU (Central Processing Unit) (not shown), and may be realized by the CPU executing data and programs stored in a memory (not shown). It may be.

  Control unit 10 receives currents Iu and Iw received from current sensors 41 and 42, voltages Vu and Vw received from voltage sensors 51 and 52, and received currents Iup and Iwp received from current sensors 61 and 62, respectively. Based on the above, switching control signals S1 to S6 for controlling on / off of the transistors Q1 to Q6 are generated according to a control method described later, and the inverter 20 is controlled.

<Configuration of Control Unit 10A>
FIG. 2 is a schematic diagram showing a configuration of control unit 10A according to the first embodiment. Referring to FIG. 2, control unit 10A includes a current value control unit 100A, a current frequency setting unit 110A, an isolated operation determination unit 120A, and a drive unit 130A. The control unit 10A corresponds to the control unit 10 shown in FIG. 2, but for the sake of distinction from the other embodiments, an additional code such as “A” is attached for convenience. The same applies to the second embodiment.

  Current value control unit 100A includes a U-phase current value control unit 101A that controls a current value flowing through voltage line U and a W-phase current value control unit 102A that controls a current value flowing through voltage line W. The U-phase current value control unit 101A constantly monitors the power reception current Iup at the power reception point P of the voltage line U, and the W-phase current value control unit 102A always monitors the power reception current Iwp at the power reception point P of the voltage line W. doing.

  Further, the U-phase current value control unit 101A sets a target value current Iu * that is a target value of the output current to the voltage line U based on the received current Iup. Specifically, the U-phase current value control unit 101A is configured so that the received current Iup becomes the received power target value current Iup * (here, 0A) in order to prevent a reverse flow from the storage battery 4 to the system power supply 8. Set the target current Iu *. More specifically, U-phase current value control unit 101A increases target value current Iu * when power reception current Iup <0, and decreases target value current Iu * when power reception current Iup> 0. Note that the amount by which the target value current Iu * is increased or decreased may be a predetermined amount ΔI, or may be determined according to the difference between the power reception current Iup and the power reception target value current Iup *.

  The W-phase current value control unit 102A sets a target value current Iw * that is a target value of the output current to the voltage line W based on the received current Iwp. Specifically, the W-phase current value control unit 102A is similar to the method in which the U-phase current value control unit 101A sets the target value current Iu *, and the received current Iwp is the received target value current Iwp * (here , 0A), the target value current Iw * is set.

  The current frequency setting unit 110A includes a U phase current frequency setting unit 111A that sets a current frequency Fu of output power to the U phase power line, and a W phase current frequency setting unit that sets the current frequency Fw of output power to the W phase power line. 112A.

  The U-phase current frequency setting unit 111A sets the current frequency Fu so as to be different from the voltage frequency of the voltage Vu detected by the voltage sensor 51 (hereinafter referred to as “detected voltage frequency Fus”). The U-phase current frequency setting unit 111A outputs the target value current Iu ** in which the frequency of the target value current Iu * is set to the current frequency Fu to the single operation determination unit 120A. The detected voltage frequency Fus of the voltage Vu is obtained from the time (cycle) from the zero cross point at which the polarity of the voltage switches to the zero cross point at which the voltage polarity switches next in the same direction.

  For example, the U-phase current frequency setting unit 111A sets the current frequency Fu to a value (Fus ± C) obtained by changing the detection voltage frequency Fus by a predetermined value C. A more specific method for setting the current frequency Fu will be described later with reference to FIGS.

  W-phase current frequency setting unit 112A sets current frequency Fw to be different from the voltage frequency of voltage Vw detected by voltage sensor 52 (hereinafter referred to as “detected voltage frequency Fws”). Specifically, the W-phase current frequency setting unit 112A sets the current frequency Fw by the same method as the setting method of the current frequency Fu in the U-phase current frequency setting unit 111A. W-phase current frequency setting unit 112A outputs target value current Iw ** in which the frequency of target value current Iw * is set to current frequency Fw to independent operation determination unit 120A.

  Here, a basic concept when determining whether or not the inverter 20 (and the storage battery 4 that is a distributed power source) is in a single operation state will be described. Normally, the power supplied from the system power supply 8 is very large compared to the power output from the storage battery 4 that is a distributed power supply. Therefore, when the power of the system power supply 8 is not reduced due to a power failure of the system power supply 8 or the like, the voltage even if the current frequency of the output power output from the inverter 20 (the above current frequencies Fu and Fw) is changed. The detection voltage frequency detected by the sensors 51 and 52 is not affected by the current frequency. That is, in this case, the detected voltage frequency is the reference frequency of the system power supply 8.

  However, when the power of the system power supply 8 is reduced due to a power failure or the like, the detected voltage frequency matches the current frequency. Specifically, the detection voltage frequency Fus matches the current frequency Fu, and the detection voltage frequency Fws matches the current frequency Fw. For this reason, the current frequency is shifted with respect to the reference frequency (detection voltage frequency) of the system power supply 8, and if the reference frequency (detection voltage frequency) changes more than a certain value due to the influence of the current frequency, the inverter It can be determined that 20 is a single operation state.

  The isolated operation determination unit 120A determines whether the inverter 20 is in the isolated operation state based on the detected voltage frequency Fus, the detected voltage frequency Fws, and a reference range of a predetermined voltage frequency. Specifically, the isolated operation determination unit 120A determines that the inverter 20 is in the isolated operation state when at least one of the detected voltage frequency Fus and the detected voltage frequency Fws is out of the reference range. Specifically, the reference range is a voltage frequency settling range. The settling range is, for example, 49 Hz to 51 Hz when the reference frequency of the system power supply 8 is 50 Hz, and 59 Hz to 61 Hz when the reference frequency of the system power supply 8 is 60 Hz. As the reference range, any value can be used as long as it is a value within which the system power supply 8 can reliably determine that the power supply 8 is in a power outage and the inverter 20 is in the single operation state.

  The drive unit 130A stops the inverter 20 when the inverter 20 is in the single operation state. Specifically, drive unit 130 </ b> A generates a switching control signal for stopping inverter 20, and outputs the generated switching control signal to inverter 20. For example, drive unit 130A generates switching control signals S1 to S6 that turn off transistors Q1 to Q6, respectively, and outputs them to inverter 20.

  The drive unit 130A normally drives the inverter 20 when the inverter 20 is not in the single operation state. Specifically, the drive unit 130A causes the current Iu detected by the current sensor 41 to become the target value current Iu **, and the current Iw detected by the current sensor 42 becomes the target value current Iw **. As described above, the switching control signals S1 to S6 for turning on / off the transistors Q1 to Q6 are generated and output to the inverter 20.

<Processing procedure>
(Current frequency setting)
With reference to FIG. 3 and FIG. 4, the current frequency shift setting process executed by the control unit 10A will be described. The shift setting process is mainly realized by the function of the current frequency setting unit 110A in the control unit 10A. As described above, since the setting method of the current frequency Fu and the setting method of the current frequency Fw are basically the same, the case where the current frequency Fu is set as a representative will be described below.

  FIG. 3 is a flowchart showing current frequency shift setting processing executed by control unit 10A according to the first embodiment.

  Referring to FIG. 3, control unit 10A acquires detected voltage frequency Fus detected by voltage sensor 51 (step S10). The controller 10A determines whether or not the current current frequency Fu (that is, the current frequency set most recently) matches the detected voltage frequency Fus (step S12).

  If current current frequency Fu and detected voltage frequency Fus match (YES in step S12), control unit 10A executes an acceleration shift process described later with reference to FIG. 4 (step S28) and ends the process. To do. On the other hand, when the current frequency Fu and the detected voltage frequency Fus do not match (NO in step S12), the control unit 10A has a frequency difference ΔF between the current current frequency Fu and the previous current frequency Fu. It is determined whether or not negative (step S14). That is, the control unit 10A determines whether the current current frequency Fu is changed in the minus direction or changed in the plus direction with respect to the previous time.

  When frequency difference ΔF is negative (YES in step S14), control unit 10A clears counter Cn that counts the number of shifts in the negative direction (Cn = 0) (step S16), and shifts in the positive direction. The counter Cp that counts the number of times of counting is counted up (Cp = Cp + 1 = 1) (step S18). Then, the control unit 10A sets the next current frequency Fu so as to increase by a predetermined value C (for example, 0.5 Hz) with respect to the detected voltage frequency Fus (step S20), and ends the process.

  When the frequency difference ΔF is not negative (positive or 0) (NO in step S14), the control unit 10A clears the positive counter Cp (Cp = 0) (step S22), and the negative counter Cn is counted up (Cn = Cn + 1 = 1) (step S24). Then, the control unit 10A sets the next current frequency Fu so as to decrease by a predetermined value C with respect to the detected voltage frequency Fus (step S26), and ends the process.

  As described above, the control unit 10A sets the current frequency Fu so as to alternately shift in the plus direction and the minus direction with respect to the detected voltage frequency Fus when no power failure occurs in the system power supply 8.

  Next, the acceleration shift process will be described with reference to FIG. FIG. 4 is a flowchart showing acceleration shift processing executed by control unit 10A according to the first embodiment.

  Referring to FIG. 4, control unit 10A determines whether or not frequency difference ΔF between current current frequency Fu and previous current frequency Fu is negative (step S50).

  When frequency difference ΔF is negative (YES in step S50), control unit 10A counts up counter Cn in the negative direction (Cn = Cn + 1) (step S52). Subsequently, the control unit 10A determines whether or not the counter Cn is equal to or greater than the predetermined number N (step S54).

  If the counter Cn is equal to or greater than the predetermined number N (YES in step S54), the control unit 10A sets the next current frequency Fu so that the amount of change in the current frequency Fu decreases according to the number of counters Cn. (Step S56), the process ends. Specifically, if the value obtained by subtracting the predetermined number of times N from the counter Cn is a (= Cn−N), the control unit 10A determines that the next current so as to decrease by C × a with respect to the current current frequency Fu. Set the frequency Fu. On the other hand, when the counter Cn is less than the predetermined number N (NO in step S54), the control unit 10A sets the next current frequency Fu so as to decrease by the predetermined value C with respect to the current current frequency Fu. After setting (step S58), the process is terminated.

  If frequency difference ΔF is not negative (NO in step S50), control unit 10A counts up positive counter Cp (Cp = Cp + 1) (step S60). Subsequently, the control unit 10A determines whether or not the counter Cp is equal to or greater than the predetermined number N (step S62).

  If the counter Cp is equal to or greater than the predetermined number N (YES in step S62), the control unit 10A sets the next current frequency Fu so that the amount of change in the current frequency Fu increases according to the number of counters Cp. (Step S64), the process ends. Specifically, if the value obtained by adding the predetermined number N from the counter Cp is a (= Cp + N), the control unit 10A determines that the current frequency Fu for the next time is increased by C × a with respect to the current current frequency Fu. Set. On the other hand, when the counter Cp is less than the predetermined number N (NO in step S62), the control unit 10A sets the next current frequency Fu so as to increase by the predetermined value C with respect to the current current frequency Fu. After setting (step S66), the process is terminated.

  As described above, the control unit 10A causes the change amount (shift amount) to increase while accelerating according to the number of times when the current frequency Fu is continuously changed in the same direction (increase direction or decrease direction). Set to.

(Inverter stop)
FIG. 5 is a flowchart showing a process when control unit 10A according to the first embodiment stops inverter 20.

  Referring to FIG. 5, control unit 10A determines whether or not at least one of detection voltage frequencies Fus and Fws is outside the reference range of the voltage frequency (step S82). If it is out of the reference range (YES in step S82), control unit 10A determines that inverter 20 is in the single operation state, stops inverter 20 (step S84), and ends the process. If it is within the reference range (NO in step S82), control unit 10A normally drives inverter 20 (step S86) and ends the process.

<Advantages>
According to the first embodiment, the voltage frequency is monitored between the U-O phase and the W-O phase, and if the voltage frequency is out of the reference range in any one, it is determined that it is in the single operation state. Stops the inverter. Therefore, even when the power (current) output to each of the U-phase and W-phase is different when connected to a single-phase three-wire system power supply, the single operation of the inverter is detected more quickly and accurately. It becomes possible. Moreover, this makes it possible to reliably prevent the inverter from operating independently.

[Embodiment 2]
In the second embodiment, a configuration for performing the isolated operation detection in any one of the U phase and the W phase will be described. In addition, since <overall configuration> and <configuration of power conditioner> in Embodiment 2 are substantially the same as those in Embodiment 1, detailed description thereof will not be repeated.

<Configuration of Control Unit 10B>
FIG. 6 is a schematic diagram showing a configuration of control unit 10B according to the second embodiment. Referring to FIG. 6, control unit 10B includes a current value control unit 100B, a current frequency setting unit 110B, an isolated operation determination unit 120B, and a drive unit 130B. Since current value control unit 100B and drive unit 130B have substantially the same configurations as current value control unit 100A and drive unit 130A shown in FIG. 3, detailed description thereof will not be repeated.

  The current frequency setting unit 110B includes a U phase current frequency setting unit 111B that sets the current frequency Fu of the output power to the U phase power line, and a W phase current frequency setting unit that sets the current frequency Fw of the output power to the W phase power line. 112B.

  Current frequency setting unit 110B acquires target value current Iu * and target value current Iw * output from current value control unit 100B. Current frequency setting unit 110B determines which of target value current Iu * and target value current Iw * is greater. When the target value current Iu * is larger than the target value current Iw *, the current frequency setting unit 110B (U-phase current frequency setting unit 111B) sets the current frequency Fu so as to be different from the detection voltage frequency Fus of the voltage Vu. At this time, current frequency setting unit 110B (W-phase current frequency setting unit 112B) maintains the previous current frequency Fw without performing shift setting of current frequency Fw.

  On the other hand, when the target value current Iu * is equal to or less than the target value current Iw *, the current frequency setting unit 110B (W-phase current frequency setting unit 112B) has a current frequency Fw that is different from the detection voltage frequency Fws of the voltage Vw. Set. At this time, the current frequency setting unit 110B (U-phase current frequency setting unit 111B) maintains the previous current frequency Fu without setting the shift of the current frequency Fu.

  From the above, the current frequency setting unit 110B shifts one of the current frequency Fu and the current frequency Fw according to the magnitude of the target value current. The current frequency shift setting method is the same as the setting method described with reference to FIGS.

  When the current frequency Fu is set by the current frequency setting unit 110B (U-phase current frequency setting unit 111B) to be different from the detection voltage frequency Fus, the isolated operation determination unit 120B sets the reference range of the voltage frequency. When disconnected, it is determined that inverter 20 is in a single operation state. In addition, when the current frequency Fw is set to be different from the detected voltage frequency Fws by the current frequency setting unit 110B (W-phase current frequency setting unit 112B), the isolated operation determination unit 120B sets the detected voltage frequency Fws as a reference for the voltage frequency. When it is out of range, it is determined that inverter 20 is in a single operation state.

<Processing procedure>
(Current frequency setting and inverter stop)
FIG. 7 is a flowchart showing a processing procedure of control unit 10B according to the second embodiment. Here, a process until the control unit 10B sets a current frequency according to the target value current and stops the inverter 20 will be described.

  Referring to FIG. 7, control unit 10B determines whether or not target value current Iu * is larger than target value current Iw * (step S102). When target value current Iu * is larger than target value current Iw * (YES in step S102), control unit 10B executes a shift setting process for current frequency Fu (step S104). Specifically, the control unit 10B executes the processes shown in FIGS. 3 and 4 described above for the current frequency Fu.

  Subsequently, the control unit 10B determines whether or not the detected voltage frequency Fus is outside the voltage frequency reference range (step S106). If it is out of the reference range (YES in step S106), control unit 10B determines that inverter 20 is in the single operation state, stops inverter 20 (step S108), and ends the process. If it is within the reference range (NO in step S106), control unit 10B normally drives inverter 20 (step S114) and ends the process.

  If target value current Iu * is equal to or smaller than target value current Iw * (NO in step S102), control unit 10B executes a shift setting process for current frequency Fw (step S110). Specifically, the control unit 10B executes the processes shown in FIGS. 3 and 4 described above for the current frequency Fw.

  Subsequently, the control unit 10B determines whether or not the detected voltage frequency Fws is outside the voltage frequency reference range (step S112). When it is out of the reference range (YES in step S112), control unit 10B determines that inverter 20 is in the single operation state, stops inverter 20 (step S108), and ends the process. If it is within the reference range (NO in step S112), control unit 10B normally drives inverter 20 (step S114) and ends the process.

<Advantages>
According to the second embodiment, only the current frequency corresponding to the phase with the larger output current from the inverter is set to be different from the detected voltage frequency. When the output current is larger, more reactive currents can be superimposed when the current frequency is shifted, and it becomes easier to detect isolated operation, so that the accuracy of isolated operation detection is maintained. Further, since the frequency is set only for one phase and the frequency is not set for the opposite phase, the opposite phase side can be operated with high efficiency, and the power quality output from the inverter can be improved overall.

[Embodiment 3]
<Overall configuration>
FIG. 8 schematically shows an entire configuration of a power supply system to which power conditioner 2C according to the third embodiment is applied.

  Referring to FIG. 8, the power supply system includes a power conditioner 2 </ b> C, a storage battery 4, loads 5 </ b> A, 5 </ b> B, 5 </ b> C, current sensors 61, 62, and a system power supply 8. Power conditioner 2C according to the third embodiment corresponds to power conditioner 2 according to the first embodiment. Since the configuration other than power conditioner 2C in the third embodiment is the same as those in the first embodiment, detailed description thereof will not be repeated.

<Configuration of power conditioner 2C>
Power conditioner 2 </ b> C includes power line 3, control unit 10 </ b> C, inverter 20, reactors 31 to 33, current sensors 41 and 42, voltage sensor 53, and DC bus 150. Since configurations of power line 3, inverter 20, reactors 31 to 33, current sensors 41 and 42, and DC bus 150 are the same as those in power conditioner 2 according to the first embodiment, detailed description thereof will be repeated. Absent.

  The voltage sensor 53 is connected between the voltage line U and the voltage line W, detects the voltage Vuw between the U and W phases, and outputs the detection result to the control unit 10C. Note that the detection result of the voltage sensor 53 includes the voltage value and the frequency of the voltage Vuw.

  Based on currents Iu and Iw received from current sensors 41 and 42, voltage Vuw received from voltage sensor 53, and received currents Iup and Iwp received from current sensors 61 and 62, control unit 10C is described later. In accordance with the control method, switching control signals S1 to S6 for controlling on / off of the transistors Q1 to Q6 are generated, and the inverter 20 is controlled.

<Configuration of Control Unit 10C>
FIG. 9 is a schematic diagram showing a configuration of a control unit 10C according to the third embodiment. Referring to FIG. 9, control unit 10C includes a current value control unit 100C, a current frequency setting unit 110C, an isolated operation determination unit 120C, and a drive unit 130C. Since current value control unit 100C and drive unit 130C have substantially the same configurations as current value control unit 100A and drive unit 130A shown in FIG. 3, detailed description thereof will not be repeated.

  The current frequency setting unit 110 </ b> C sets the current frequency Fu and the current frequency Fw to be the same, and sets the same set current frequency to be different from the detected voltage frequency Fuws detected by the voltage sensor 53. The current frequency shift setting method is the same as the setting method described with reference to FIGS. For example, the current frequency setting unit 110C sets the current frequency Fu to be different from the detection voltage frequency Fuws by the setting method described with reference to FIG. Then, the current frequency setting unit 110C also sets the current frequency Fw so as to be the set current frequency.

  Since the current frequencies Fu and Fw are set to be the same by the current frequency setting unit 110C, when the power of the system power supply 8 is reduced due to a power failure or the like, the detected voltage frequency Fuws matches the same set current frequency. Will do.

  Therefore, the isolated operation determination unit 120C determines whether or not the inverter 20 is in the isolated operation state based on the detected voltage frequency Fuws and the reference range of the voltage frequency. Specifically, the isolated operation determination unit 120C determines that the inverter 20 is in the isolated operation state when the detected voltage frequency Fus is out of the reference range.

<Advantages>
According to the third embodiment, the current frequency of the output power to each of the U phase and the W phase is set to be the same, and the current frequency is set to be different from the detection voltage frequency Fuws. Therefore, voltage detection in the U phase and the W phase is not necessary as compared with the first embodiment, so that the cost and size of the power conditioner can be reduced.

[Summary]
Embodiments of the present invention can be summarized as follows.

  (1) It is the power conditioner 2 connected between the storage battery 4 and the system power supply 8, Comprising: The inverter 20 which converts the direct current power of the storage battery 4 into single phase alternating current power, and outputs, voltage line U, and neutrality A power line 3 including a U-phase power line composed of line O, a W-phase power line composed of voltage line W and neutral line O, and supplying output power from inverter 20, voltage line U and neutral line A voltage sensor 51 that detects a detection voltage frequency Fus of a voltage between O, a voltage sensor 52 that detects a detection voltage frequency Fws of a voltage between the voltage line W and the neutral line O, and a control unit that controls the inverter 20 10A. Control unit 10A sets current frequency Fu of output power to the U-phase power line so as to be different from detection voltage frequency Fus, and sets current frequency Fw of output power to the W-phase power line so as to be different from detection voltage frequency Fws. Based on the current frequency setting unit 110A, at least one of the detected voltage frequencies Fus and Fws, and the settling range of the voltage frequency, the single operation determination unit 120A that determines whether or not the inverter 20 is in the single operation state, and the inverter 20 And a drive unit 130 </ b> A that stops the inverter 20 when it is in a single operation state.

  According to the above configuration, even when the power (current) output to each of the U-phase and the W-phase is different from that of the single-phase three-wire system power supply, it can be detected with high accuracy. .

  (2) The isolated operation determination unit 120A determines that the inverter 20 is in the isolated operation state when at least one of the detected voltage frequency Fus and the detected voltage frequency Fws is outside the voltage frequency settling range.

  According to the said structure, the independent operation of an inverter can be detected earlier. In addition, this makes it possible to reliably prevent the inverter from operating independently.

  (3) The control unit 10B monitors the received current Iup at the receiving point of the voltage line U and the received current Iwp at the receiving point of the voltage line W, and the target value of the output current to the voltage line U based on the received current Iup And a current value control unit 100B that sets a target value current Iw * that indicates a target value of the output current to the voltage line W based on the received current Iwp. When the target value current Iu * is larger than the target value current Iw *, the current frequency setting unit 110B sets the current frequency Fu different from the detection voltage frequency Fus, and the target value current Iu * is equal to or less than the target value current Iw *. In this case, the current frequency Fw is set to be different from the detection voltage frequency Fws.

  According to the above configuration, since the current frequency is set only for one of the phases with a large output current, the power quality output by the inverter can be improved.

  (4) When the current frequency Fu is set by the current frequency setting unit 110B, the single operation determination unit 120B determines that the inverter 20 is in the single operation state when the detected voltage frequency Fus is outside the voltage frequency settling range. When the current frequency Fw is set by the current frequency setting unit 110B, it is determined that the inverter 20 is in the single operation state when the detected voltage frequency Fws is outside the voltage frequency settling range.

  According to the above configuration, since the isolated operation is detected based on the voltage frequency of the phase with the larger output current from the inverter, the accuracy of the isolated operation can be maintained.

  (5) A power conditioner 2 </ b> C connected between the storage battery 4 and the system power supply 8, which converts the DC power of the power supply into single-phase AC power and outputs it, a voltage line U, and a neutral line A U-phase power line composed of O, a W-phase power line composed of a voltage line W and a neutral line O, and a power line 3 for supplying output power from the inverter 20; The voltage sensor 53 which detects the detection voltage frequency Fuws of the voltage between, and the control part 10C which controls the inverter 20 are provided. The control unit 10C sets the current frequency Fu of the output power to the U-phase power line and the current frequency Fw of the output power to the W-phase power line to be the same, and the voltage sensor 53 detects the same set current frequency. Whether or not the inverter 20 is in the single operation state based on the current frequency setting unit 110C that is set to be different from the detected voltage frequency Fuws, the detected voltage frequency Fuws detected by the voltage sensor 53, and the settling range of the voltage frequency. An independent operation determination unit 120C for determining whether or not the independent operation determination unit 120C determines that the inverter 20 is in an independent operation state, and a drive unit 130C that stops the inverter 20.

  According to the above configuration, the current frequency Fu and the current frequency Fw are set to be the same, and the current frequency is set to be different from the detection voltage frequency Fuws. Therefore, it is possible to detect isolated operation with high accuracy and to promote cost reduction and downsizing of the power conditioner.

  (6) The isolated operation determination unit 120C determines that the inverter 20 is in the isolated operation state when the detected voltage frequency Fuws is outside the voltage frequency settling range.

  According to the above configuration, it is possible to provide a power conditioner capable of detecting an isolated operation without preparing two voltage sensors as compared with the power conditioner according to the first embodiment.

  The configuration illustrated as the above-described embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part of the configuration is omitted without departing from the gist of the present invention. It is also possible to change the configuration.

  In the above-described embodiment, the processing and configuration described in the other embodiments may be adopted as appropriate.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  2, 2C power conditioner, 3 power line, 4 storage battery, 5 power load, 8 system power supply, 10, 10A, 10B, 10C control unit, 20 inverter, 31, 32, 33 reactor, 41, 42, 61, 62 current sensor , 51, 52, 53 Voltage sensor, 100A, 100B, 100C Current value control unit, 101A U phase current value control unit, 102A W phase current value control unit, 110A, 110B, 110C Current frequency setting unit, 111A, 111B U phase Current frequency setting unit, 112A, 112B W-phase current frequency setting unit, 120A, 120B, 120C Independent operation determination unit, 130A, 130B, 130C driving unit, 150 DC bus.

Claims (4)

A power conditioner connected between a DC power supply and a system power supply,
An inverter that converts the DC power of the DC power source into single-phase AC power and outputs it;
A first power line constituted by a first voltage line and a neutral line; and a second power line constituted by a second voltage line and the neutral line, and supplying output power from the inverter. A power supply line;
First detection means for detecting a first voltage frequency of a voltage between the first voltage line and the neutral line;
Second detection means for detecting a second voltage frequency of a voltage between the second voltage line and the neutral line;
Control means for controlling the inverter,
The control means includes
The first current frequency of the current output to the first power line is set to be different from the first voltage frequency, and the first current frequency to be output to the second power line is set to be different from the second voltage frequency. Setting means for setting the current frequency of 2;
Determining means for determining whether or not the inverter is in a single operation state based on at least one of the first voltage frequency and the second voltage frequency and a reference range of a predetermined voltage frequency;
A power conditioner including stop means for stopping the inverter when the inverter is in a single operation state.   2. The determination unit according to claim 1, wherein the determination unit determines that the inverter is in a single operation state when at least one of the first voltage frequency and the second voltage frequency is out of a reference range of the voltage frequency. Power conditioner. The control means includes
Current monitoring means for monitoring a first power receiving current at a power receiving point of the first voltage line and a second power receiving current at the power receiving point of the second voltage line;
A first target value current indicating a target value of an output current to the first voltage line is set based on the first power receiving current, and the second voltage line is set based on the second power receiving current. Target value setting means for setting a second target value current indicating a target value of the output current of
The setting means includes
If the first target value current is greater than the second target value current, the first current frequency is set to be different from the first voltage frequency;
The power conditioner according to claim 1, wherein when the first target value current is equal to or less than the second target value current, the second current frequency is set to be different from the second voltage frequency. The determination means includes
When the first current frequency is set by the setting means, it is determined that the inverter is in a single operation state when the first voltage frequency is out of a reference range of the voltage frequency;
4. When the second current frequency is set by the setting means, it is determined that the inverter is in a single operation state when the second voltage frequency is out of a reference range of the voltage frequency. The listed inverter.

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