JP4612342B2 - Power conversion device and superconducting power storage device - Google Patents

Description

  The present invention relates to a power conversion device and a superconducting power storage device for compensating for a sag.

  A conventional superconducting power storage device (SMES) for compensating for a sag supply that continuously supplies required power to a load when the power supply system is sag (instantaneous voltage drop) is a superconducting power storage device that stores electromagnetic energy. The SMES coil and a power converter that converts the DC power output from the SMES coil into AC power and supplies the AC power to the load. Since the superconducting coil is a current source, the circuit configuration can be simplified by applying a current source converter.

As a current source converter, a direct multiplexing method shown in FIG. 11 has been proposed (see, for example, Non-Patent Document 1). In the case of this method, since a cross current is generated between the unit converters 1, a cross current suppression inductance and a cross current suppression control function are required. Further, since the current capacity is increased due to the parallel system, there is a problem that the capacity of the cooling device of the SMES coil increases and the cost of the entire system increases. Further, there is a problem in that the loss of the converter increases as the current capacity increases.
Nagai et al., “Development of Multiple Current Source Converter Applying Multiple Space Vector Control”, 1998, D. D. 118, 5 pp. 630-636

  In the conventional power converter in SMES, a cross current is generated. Therefore, in order to suppress the cross current, an inductance for suppressing the cross current and a cross current suppression control are required. Installation of a cross-flow suppression reactor increases the size and weight of the device. Furthermore, a cross current suppression control function is required, leading to an increase in the cost of the power conversion device. Further, in terms of cost, because of the parallel system, it is necessary to suppress the cost of the cooling device accompanying an increase in the current capacity of the SMES coil.

  The present invention provides a power conversion device and a superconducting power storage device that have a simple and high-performance control system and can significantly reduce the size, weight, capacity, and cost of the SMES coil, cooling device, and main circuit. Objective.

The invention of claim 1 is a power converter, and is a plurality of units that are connected in series to each other and connected to a current source to convert DC power supplied from the current source into one phase of three-phase AC power in two stages. A converter, a capacitor connected to the output terminal of each unit converter, a winding connected to the two-stage capacitor corresponding to one phase of three-phase AC power, and a corresponding three-phase power system A three-winding transformer having a winding connected to one phase of the three-phase AC power supply system, a voltage detection device for detecting the voltage of the three-phase AC power supply system, a voltage detection device for detecting the voltage of each capacitor, and the three-phase AC A current detection device that detects the current of the power supply system, and when detecting the occurrence of a momentary voltage drop in the power supply system, the feedforward control using the detected value of the system current and the capacitor voltage control enable stable capacitor Voltage A three-phase capacitor voltage detection value calculated by adding the voltages of the output-end capacitors of the two-stage unit converters constituting each phase and a system-line voltage detection signal. The capacitor voltage control device that outputs the capacitor voltage control DQ current command value as a result of the capacitor voltage control, the capacitor voltage control DQ current command value, and the system current feedforward control DQ current command value are input. A current command control device that outputs a phase output current command, the three-phase output current command, and a three-phase U-phase first-stage unit converter gate signal, U-phase second-stage unit converter gate signal, three-phase V-phase first-stage unit converter gate signal, V-phase second-stage unit converter gate signal, three-phase W-phase first-stage unit converter gate signal, W-phase second-stage unit converter gate signal In a vessel And a PWM control device that outputs the power supply, and has a voltage sag compensation control function that stably supplies required power to a load for a predetermined time during a sag of the power supply system. To do.

The invention of claim 2 is a plurality of unit converters that are connected in series with each other and connected to a current source to convert DC power supplied from the current source into one phase of three-phase AC power in two stages, A capacitor connected to each output terminal of the unit converter, a winding connected to each of the two-stage capacitors corresponding to one phase of the three-phase AC power, and one phase of the corresponding three-phase power supply system A three-winding transformer having windings, a voltage detection device for detecting the voltage of the three-phase AC power supply system, a voltage detection device for detecting the voltage of each capacitor, and a current of the three-phase AC power supply system And a control device that stably controls the capacitor voltage even during a transition by feedforward control using the detected value of the system current and capacitor voltage control when it is detected that an instantaneous drop has occurred in the power supply system When The control device inputs a three-phase capacitor voltage detection value, which is a value obtained by adding together capacitor voltages between the same type of output capacitor voltages of each unit converter, and performs PI control as a result of simulated system current control A simulated system current control device that outputs an output DQ current command value; a current command control device that inputs the PI control output DQ current command value and a system current detection signal and outputs a three-phase output current command; Input the output current command, three-phase U-phase first-stage unit converter gate signal, U-phase second-stage unit converter gate signal, three-phase V-phase first-stage unit converter gate signal, V-phase two-stage A PWM controller that outputs a unit converter gate signal, a three-phase W phase first stage unit converter gate signal, and a W phase second stage unit converter gate signal to each unit converter, At a predetermined time during the instantaneous drop of the power system Between, and having a sag compensation control function stably supplying the required power to the load.

  According to the present invention, there is provided a power conversion device and a superconducting power storage device that have a simple and high-performance control system and can significantly reduce the size, weight, capacity, and cost of a SMES coil, a cooling device, and a main circuit. be able to.

(First embodiment)
(Constitution)
FIG. 1 shows a configuration of a power conversion device 101 according to the first embodiment of this invention.
The load 112 is connected to the power supply system 111 via the grid interconnection device 109, and the power conversion device 101 is connected between the grid interconnection device 109 and the load 112.

  The power conversion device 101 includes a plurality of unit converters 102 connected in series with each other to convert DC power into AC power, a capacitor 103 connected to an output terminal of the unit converter 102, a capacitor 103, and a power supply system 111. Transformer 104 to be connected, voltage detection device 106 for detecting the system voltage, voltage detection device 107 for detecting the voltage of the capacitor 103, system current detection device 108 for detecting the system current, and an instantaneous drop occurred in the system When this is detected, feed-forward control of the system current is performed, and transients are made by capacitor voltage feedback control in which the capacitor voltage vector amplitude and system phase voltage vector phase immediately before the voltage sag are set to the capacitor voltage amplitude command value and the capacitor voltage phase command value, respectively. And a control device 105 that stably controls the capacitor voltage. There.

  The unit converters 102 are connected in series with each other. The unit converters 102 at both ends connected in series are respectively connected to both ends of a current source 110 formed of a SMES coil. A capacitor 103 is connected between the output terminals of the unit converter 102. Capacitor 103 is connected to the secondary side terminal of transformer 104. One terminal on the primary side of each transformer 104 is connected to the power line of each phase of the power supply system 111, and the other terminal is connected to one terminal of the other transformer 104.

(Function)
The control device 105 detects the line voltage of the power supply system 111 via the voltage detection device 106 and detects the voltage of the capacitor 103 at the output terminal of each unit converter 102 via the voltage detection device 107.

  When the magnitude of the system voltage vector calculated from the detected system voltage signal is smaller than the reference value, the control apparatus 105 determines that an instantaneous drop has occurred in the system, opens the system interconnection apparatus 109, and loads the load 112. Is disconnected from the power supply system 111.

  The control device 105 inputs the voltage signal between the three-phase system lines detected by the voltage detection device 106, and the system line whose phase is delayed by 90 degrees with respect to the reference coordinate axis in the horizontal axis direction in the stationary coordinate system by the three-phase two-phase conversion. Generate an inter-voltage vector. The phase of the phase voltage vector of the power supply system 111 is calculated by adding 60 degrees to the phase of the system line voltage vector delayed by 90 degrees. When a voltage drop is detected, the phase of the phase voltage vector immediately before the voltage drop is used as the capacitor voltage vector phase command signal. Further, the magnitude of the voltage vector of the capacitor 103 immediately before the occurrence of the instantaneous drop is used as the capacitor voltage amplitude command signal. Based on the capacitor voltage amplitude command signal and capacitor voltage vector phase command signal thus calculated, the voltage of the capacitor 103 is feedback-controlled.

Further, the control device 105 improves the transient response performance by feedforward control using the detected value of the system current.
As a result, when a voltage sag occurs in the power supply system 111, the power conversion device 101 continuously supplies power to the load 112 for a predetermined time and performs sag compensation control.

(effect)
According to the power conversion device of the present embodiment, it is possible to increase the DC voltage of the SMES coil and decrease the DC current by connecting a plurality of unit converters 102 in series to increase the capacity. This eliminates the need for the cross current suppression reactor and control required in the conventional parallel-type SMES power converter, thereby reducing the size, weight, and cost of the power converter. Further, since the direct current capacity is reduced, the current capacity and cost of the SMES coil and the cooling device can be reduced.

  Furthermore, the feedforward control using the detected value of the system current makes it possible to improve the transient response performance, and when the system interconnection device 109 is OFF, the overcurrent flows through the system or the load voltage decreases. Thus, it is possible to provide a SMES power conversion device for low voltage, high performance instantaneous voltage compensation.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS.
(Constitution)
FIG. 2 shows a configuration of the power conversion device 201 of the present embodiment.

  The load 112 is connected to the power supply system 111 via the grid interconnection device 209, and the power conversion device 201 is connected between the grid interconnection device 209 and the load 112.

  The power conversion device 201 includes a unit converter 202, a capacitor 203, a three-winding transformer 204, a control device 205, a voltage detection device 206 that detects a system line voltage of the power supply system 111, and each unit converter 202. A voltage detection device 207 connected between the AC output terminals, a current detection device 208 that detects a three-phase AC current of the power supply system 111, and a grid interconnection that connects the load 112 and the power conversion device 201 to the power supply system 111. Device 209.

  In this embodiment, six unit converters 202 are connected in series to constitute a power conversion device 201. The unit converters 202 at both ends connected in series are respectively connected to both ends of the current source 110 formed of a SMES coil. A capacitor 203 is connected between the output terminals of the unit converter 202. The capacitor 203 is connected to the secondary winding of the three-winding transformer 204. One terminal on the primary side of the three-turn transformer 204 is connected to the power line of each phase of the power supply system 111, and the other terminal is connected to the other terminal of the other three-turn transformer 204.

FIG. 3 shows the configuration of unit converter 202 in the present embodiment.
The unit converter 202 has a single-phase bridge configuration. Each arm includes a reverse blocking diode 301 and a switching element 302. The unit converter 202 is a low-cost power converter by using a general single-phase bridge and a general-purpose element.

(Function)
(Detection of system voltage, capacitor voltage, system current)
The control device 205 detects the system voltage via the voltage detection device 206 and also detects the voltage of the capacitor 203 at the output terminal of each unit converter 202 via the voltage detection device 207. Further, the control device 205 detects a three-phase system current via the current detection device 208.

(Generation of capacitor voltage phase command signal)
The control device 205 inputs the three-phase system voltage detected via the voltage detection device 206 to the primary delay filter.
The control device 205 performs three-phase to two-phase conversion on the first-order lag output signal obtained by the first-order lag filter, and generates a two-phase system line voltage signal whose phase is delayed by 90 degrees. The control device 205 calculates the phase of the system line voltage vector from the two-phase system line voltage signal. The control device 205 generates a phase signal of the system phase voltage vector by adding π / 3 [rad] to this system line voltage vector phase signal. The control device 205 uses the phase signal of the system phase voltage vector as the capacitor voltage vector phase command signal.

(Capacitor voltage feedback)
The control device 205 adds the detected voltages of the first-stage and second-stage capacitors 203 to generate a U-phase capacitor voltage that is one of the three phases.

  Further, the control device adds the voltages of the capacitors 203 in the third and fourth stages to generate a V-phase capacitor voltage that is one of the three phases.

  Further, the control device 205 adds the voltages of the capacitors 203 in the fifth and sixth stages to generate a W-phase capacitor voltage that is one of the three phases. The control device 205 performs three-phase to two-phase conversion on the UVW three-phase capacitor voltage signal to generate a two-phase capacitor voltage.

  The control device 205 calculates the positive square root of the square sum of the two-phase capacitor voltage as the magnitude of the capacitor voltage vector.

  The control device 205 outputs the magnitude of the calculated capacitor voltage vector as a three-phase capacitor voltage amplitude command signal by passing through the first-order lag filter. The three-phase capacitor voltage amplitude command signal is three-phase to two-phase converted, and a two-phase capacitor voltage amplitude signal is output.

  The control device 205 DQ-converts the two-phase capacitor voltage amplitude signal with the capacitor voltage vector phase command signal, and outputs a DQ capacitor voltage amplitude signal. The DQ conversion is a coordinate conversion for converting a stationary coordinate system component into a rotating coordinate system that rotates at the same frequency as the system voltage.

(System current feedforward control)
The control device 205 inputs the detected three-phase system current to the first-order lag filter, and performs three-phase to two-phase conversion using the three-phase system current signal output from the first-order lag filter.
The control device 205 performs DQ conversion on the two-phase system current obtained by three-phase to two-phase conversion using the capacitor voltage vector phase command signal, and outputs a DQ system current signal.

(Instantaneous voltage drop detection judgment)
The control device 205 calculates the positive square root of the square sum of each component of the two-phase system line voltage signal and outputs it as a system line voltage vector amplitude signal. If this system line voltage vector amplitude signal is below the threshold value, it is determined that a voltage sag has occurred in the system, and a voltage sag detection signal is output.

(Standby control)
When the power supply system 111 is healthy, the control device 205 conducts the upper and lower arms of each unit converter 202 to hold the current of the current source 110 (SMES coil) and stands by.

(Instantaneous voltage drop compensation control)
If a voltage drop occurs in the power supply system 111, the control device 205 holds the three-phase capacitor voltage amplitude command signal and the capacitor voltage vector phase command signal immediately before the voltage drop, and the capacitor voltage vector phase command signal by the system power supply frequency. Advance the phase of.

Control device 205 calculates a three-phase capacitor voltage command signal using the three-phase capacitor voltage amplitude command signal and the capacitor voltage vector phase command signal.
The control device 205 performs three-phase to two-phase conversion on the three-phase capacitor voltage command signal, performs DQ conversion on the capacitor voltage vector phase command signal, and generates a DQ capacitor voltage command signal.

The control device 205 converts the two-phase capacitor voltage detection signal into a DQ capacitor voltage detection signal using the capacitor voltage vector phase command signal.
The control device 205 generates a capacitor voltage control output signal by PI control using the DQ capacitor voltage command signal and the DQ capacitor voltage detection signal.

The control device 205 adds the capacitor voltage control output signal and the DQ system current signal to generate a DQ current command signal.
The control device 205 adds the DQ system current signal that is the feedforward control of the system current, thereby turning off the system interconnection device 209 at high speed and shutting off the power system 111.

  As a result, the power conversion device 201 continues to supply power stably to the load 112 during the sag period. As a result, when a power sag occurs in the power supply system 111, the power conversion device 201 stably supplies power to the load 112 for a predetermined time, and performs power sag compensation control.

(effect)
According to the second embodiment, a SMES power converter can be easily configured by using a plurality of single-phase bridge circuits. As a result, a low-cost power conversion device can be constructed and the reliability of the system can be improved. Further, since the direct current capacity is reduced, the current capacity and cost of the SMES coil and the cooling device can be reduced.

  Furthermore, the feedforward control using the detected value of the system current makes it possible to improve the transient response performance, and when the system interconnection device 209 is OFF, the overcurrent flows through the system or the load voltage decreases. Thus, it is possible to provide a SMES power conversion device for low voltage, high performance instantaneous voltage compensation.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS. The present embodiment relates to the control device 205 shown in FIG.

(Constitution)
As shown in FIG. 4, the control device 205 in the present embodiment includes a capacitor voltage control device 401, a current command control device 402, and a PWM control device 403.

  As shown in FIG. 5, the capacitor voltage control device 401 includes three-phase / two-phase conversion means 501a, 501b, 501c, 501d for delaying the voltage vector phase by 90 degrees, capacitor voltage amplitude detection means 502, and capacitor voltage amplitude control means 503. System line voltage phase detection means 504, adder 525, capacitor voltage phase control means 505, capacitor voltage command generation means 506, two-phase DQ conversion means 507a, 507b, 507c, subtraction means 508, PI control means 509, primary delay filters 523 a, 523 b, 523 c, an adder 525, and instantaneous drop determination means 526 are provided.

  As shown in FIG. 6, the current command control device 402 includes a limiter unit 601, a vector limit unit 602, a minimum ON pulse width control unit 603, a DQ two-phase conversion unit 604, and a two-phase three-phase conversion unit 605. And three-phase current command control means 606.

FIG. 7 shows the configuration of one PWM control device 403.
The PWM controller 403 includes a first-stage converter PWM controller 701 and a second-stage converter PWM controller 702. The first-stage converter PWM control device 701 includes a PWM control device 703, a NOT circuit 704, and a polarity inversion circuit 705. The second stage converter PWM control device 702 has the same configuration as the first stage converter PWM control device 701, but the phase of the carrier signal 711 is 90 relative to the carrier signal 706 of the first stage converter PWM control device 701. It is late.

(Function)
As shown in FIG. 4, the capacitor voltage control device 401 constituting the control device 205 inputs a three-phase capacitor voltage detection value 404 and a system line voltage detection signal 210, and the capacitor voltage control DQ current is obtained as a result of the capacitor voltage control. The command value 405 is output. Here, the three-phase capacitor voltage detection value 404 is a three-phase voltage calculated by adding the voltages of the output end capacitors 203 of the two-stage unit converter 202 constituting each phase.

The current command control device 402 receives the capacitor voltage control DQ current command value 405 and the system current feedforward control DQ current command value 406 and outputs a three-phase output current command 407.
The PWM controller 403 receives a three-phase output current command 407, receives a U-phase first-stage unit converter gate signal 408, a U-phase second-stage unit converter gate signal 409, and a V-phase first-stage unit converter gate signal. 410, V phase second stage unit converter gate signal 411, W phase first stage unit converter gate signal 412, and W phase second stage unit converter gate signal 413 are output to each unit converter 202.

  As shown in FIG. 5, the three-phase to two-phase conversion means 501a constituting the capacitor voltage control device 401 receives the three-phase capacitor voltage detection value 404, and the two-phase capacitor voltage that is the two-axis component of the stationary two-phase coordinate system. Convert to signal 511.

  Capacitor voltage amplitude detector 502 receives a two-phase capacitor voltage signal 511 and outputs the positive square root of the sum of squares as capacitor voltage amplitude 512.

  The first-order lag filter 523a receives the capacitor voltage amplitude 512, removes the high frequency ripple component of the capacitor voltage amplitude 512, and outputs a capacitor voltage amplitude command filter output value 524.

  Capacitor voltage amplitude control means 503 receives capacitor voltage amplitude command filter output value 524 and voltage sag occurrence signal 522. When voltage sag occurs, capacitor voltage amplitude command filter output value 524 immediately before the time of voltage sag is converted to capacitor voltage. This is held as the amplitude command value 513.

  The three-phase / two-phase conversion means 501b inputs the three-phase system line voltage detection signal 210 via the first-order lag filter 523b, and converts the system line voltage into a voltage vector signal having a phase delay of 90 degrees.

  The line voltage phase detection means 504 receives a voltage vector whose phase is delayed by 90 degrees, calculates a system voltage phase signal, and outputs it. Adder 525 adds the phase of the system voltage phase signal and π / 3 [rad], and outputs system phase voltage phase signal 514.

Capacitor voltage phase control means 505 inputs system phase voltage phase signal 514 and voltage sag occurrence signal 522, and when voltage sag occurs, system voltage phase signal 514 immediately before the occurrence of voltage sag is used as capacitor voltage phase command signal. And the phase is advanced at the rated frequency of the system voltage, and a capacitor voltage phase command signal 515 is output.
Capacitor voltage command generation means 506 receives capacitor voltage amplitude command value 513 and capacitor voltage phase command signal 515 and outputs a three-phase capacitor voltage command value 516.

The three-phase / two-phase conversion means 501c receives a three-phase capacitor voltage command value 516 and outputs a DQ capacitor voltage command value 517 of a stationary two-phase component.
The two-phase DQ conversion means 507a receives the two-phase capacitor voltage command value 517 and the capacitor voltage phase command signal 515 and outputs the DQ capacitor voltage command value 518.

Subtraction means 508 calculates DQ capacitor voltage deviation 520 by subtracting DQ capacitor voltage detection value 519 from DQ capacitor voltage command value 518.
The PI control means 509 receives the DQ capacitor voltage deviation 520 and outputs a capacitor voltage control DQ current command value 405 as a result of PI (integration and integration) control.

The three-phase / two-phase conversion 501d receives a three-phase system current detection signal 211 and outputs a two-phase system current detection signal by the three-phase / two-phase conversion.
The two-phase DQ conversion means 507c receives a two-phase grid current detection signal and outputs a grid current feedforward control DQ current command value 406 by DQ conversion.

  As shown in FIG. 6, the limiter means 601 constituting the current command control device 402 adds a system current feedforward control DQ current command value 406 and a capacitor voltage control DQ current command value 405 to generate a DQ current command value 600. When the absolute value of the D-axis current command value and the Q-axis current command value exceeds the respective limit values, a limit DQ current command 607 that limits the DQ-axis current command value to a predetermined limit value is displayed. Output.

  The vector limit means 602 receives the limit DQ current command 607, and when the amplitude of the current vector composed of the D-axis and Q-axis limit current commands exceeds the specified value, the amplitude of the current vector becomes the specified value. Thus, the limit current command for the D axis and the Q axis is converted, and the vector limit DQ current command 608 is output.

  The minimum ON pulse width control means 603 receives the vector limit DQ current command 608, and as a result of PWM control using this current command, the PWM shorter than the minimum ON pulse width defined by the elements constituting the power converter 202. A minimum ON pulse width control DQ current command 609, which is a value obtained by limiting the vector limit DQ current command value, is output so that no pulse is generated.

The DQ two-phase conversion means 604 receives the minimum ON pulse width control DQ current command 609 and the capacitor voltage phase command value 515 and outputs a two-phase current command 610.
The two-phase / three-phase conversion means 605 receives the two-phase current command 610, performs two-phase / three-phase conversion, and outputs a voltage drop compensation control three-phase output current command 612.

  The three-phase current command control means 606 receives the standby control three-phase output current command 613, the sag compensation control three-phase output current command 612, and the sag occurrence signal 522. The three-phase current command control means 606 outputs the standby control three-phase output current command 613 as the three-phase output current command 407 unless the voltage sag occurrence signal 522 is set to the value of the voltage sag occurrence. If the voltage sag occurrence signal 522 is set to the value of the voltage sag occurrence, the voltage sag compensation control three-phase output current command 612 is output as the three-phase output current command 407.

  As shown in FIG. 7, the PWM signal generator 703 constituting the first-stage converter PWM control device 701 receives a current command signal corresponding to one of the three-phase output current commands 407 and the carrier signal 706. If the current command signal corresponding to one of the phase output current commands 407 is larger than the carrier signal 706, a PWM signal for turning on the switching element is output, and if not, a PWM signal for turning off the switching element is output. The generated PWM signal is output via the NOT circuit 704 as gate signals 707 and 708 of the switching elements constituting the upper arm of the single-phase bridge circuit.

  PWM control for the switching elements constituting the lower arm of the single-phase bridge circuit is performed using a current command signal obtained by inverting the current command signal 407 for one phase by the polarity inverting circuit 705. PWM control is performed by the inverted current command signal and carrier signal 706, and a gate signal for the switching element constituting the lower arm of the single-phase bridge circuit is output.

  The PWM control for the second stage unit converter is realized by shifting the phase of the carrier signal 711 by 90 ° from the phase of the carrier signal 706 in the PWM control for the first stage unit converter. The reason why the phase difference of 90 ° is provided in the PWM control carrier signal for the first-stage and second-stage unit converters is to suppress the generated harmonics.

The other-phase PWM control is similarly realized by using the current command signal 407 of the other phase.
As a result of the above control, the output-end filter capacitor voltage of each unit converter can be controlled to a voltage immediately before the system instantaneously drops.
This control makes it possible to realize the required power compensation for the load when the system is instantaneously low.

(effect)
According to the power converter of the third embodiment, the conventional triangular wave comparison PWM control can be used. As a result, the cost of the control system can be suppressed, and a low-cost power conversion device can be provided. Further, since the direct current capacity is reduced, the current capacity and cost of the SMES coil and the cooling device can be reduced.

  Furthermore, the feedforward control using the detected value of the system current makes it possible to improve the transient response performance, and solves the problem that the overcurrent flows through the system or the load voltage decreases when the system interconnection device 209 is OFF. In addition, it is possible to provide a SMES power converter for compensating for a sag with high performance at low cost.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS. The present embodiment also relates to the control device 205 shown in FIG. 2 as in the third embodiment.

(Constitution)
As shown in FIG. 8, the control device 205 in the present embodiment includes a simulated system current control device 801, a current command control device 802, and a PWM control device 403.

  As shown in FIG. 9, the simulated system current control device 801 includes a system line voltage phase detection unit 901, a three-phase / two-phase conversion unit 902 a, 902 b, 902 c that delays the phase of the input voltage vector by 90 degrees, and a capacitor voltage. Amplitude detection means 903, first-order lag filter 927, capacitor voltage amplitude control means 904, capacitor voltage phase control means 906, simulated system three-phase voltage generation means 907, two-phase DQ conversion means 908a, 908b, subtraction Means 909, simulated system current calculation means 910, and PI control means 911 are provided.

  As shown in FIG. 10, the simulated system current calculation means 910 includes subtractors 1001a and 1001b, a divider 1002, multipliers 1003a and 1003b, an integrator 1004, and a delay element 1005.

(Function)
As shown in FIG. 8, the simulated system current control device 801 of the control device 205 inputs a three-phase capacitor voltage detection value 404 and outputs a PI control output DQ current command value 805 as a result of the simulated system current control. Here, the three-phase capacitor voltage detection value 404 is a value obtained by adding the capacitor voltages between the same type of the output capacitor voltages of the unit converters.

  The current command control device 802 receives the PI control output DQ current command value 805 and the system current detection signal 211 and outputs a three-phase output current command 407.

  The PWM controller 403 receives a three-phase output current command 407, receives a U-phase first-stage unit converter gate signal 408, a U-phase second-stage unit converter gate signal 409, and a V-phase first-stage unit converter gate signal. 410, V phase second stage unit converter gate signal 411, W phase first stage unit converter gate signal 412, and W phase second stage unit converter gate signal 413 are output to each unit converter 202.

  As shown in FIG. 9, the three-phase two-phase conversion means 902a of the simulated system current control device 801 receives a three-phase capacitor voltage detection value 404, and a two-phase capacitor voltage signal that is a biaxial component of a stationary two-phase coordinate system. Convert to 914.

  The capacitor voltage amplitude detector 903 receives the two-phase capacitor voltage signal 914 and outputs the positive square root of the sum of squares as the capacitor voltage amplitude 915. The first-order lag filter 927 receives the capacitor voltage amplitude 915 and outputs a capacitor voltage amplitude command filter output value 928 from which the high frequency ripple has been removed.

  Capacitor voltage amplitude control means 904 receives capacitor voltage amplitude command filter output value 928 and sag occurrence signal 522, and when sag occurs, capacitor voltage amplitude 915 immediately before the occurrence of sag is obtained as capacitor voltage amplitude command value. 917 is held.

The system line voltage detection signal 210 is input to the three-phase / two-phase conversion means 902c via the first-order lag filter 523b.
The three-phase / two-phase conversion means 902c receives the first-order lag filter output value of the system line voltage detection signal 210 and outputs a 2-phase system line voltage phase signal 912.

The system line voltage phase detection means 901 receives the 2-phase system line voltage phase signal 912 and outputs the system line voltage phase signal 913.
The adder 905 adds π / 3 [rad] to the system voltage level signal 913 and outputs a capacitor voltage phase signal 918.

  Capacitor voltage phase control means 906 receives capacitor voltage phase signal 918 and voltage sag occurrence signal 522, and when voltage sag occurs, capacitor voltage phase signal 918 immediately before the voltage sag occurs is used as a reference for the capacitor voltage phase command signal. The value is held as a value, the phase is advanced at the rated frequency of the system voltage, and the capacitor voltage phase command signal 919 is output.

The simulated system three-phase voltage generation means 907 receives the capacitor voltage amplitude command value 917 and the capacitor voltage phase command signal 919, and outputs a simulated system power supply three-phase voltage command value 920.
The three-phase / two-phase conversion means 902b receives the simulated system power supply three-phase voltage command value 920 and outputs a simulated two-phase power supply voltage two-phase voltage command value 921 of a stationary two-phase component.

The two-phase DQ conversion means 908a inputs the simulated system power supply two-phase voltage command value 921 and the capacitor voltage phase command value 919 and outputs the simulated system power supply DQ voltage 922.
The subtracting unit 909 calculates the simulated system DQ voltage 924 by subtracting the capacitor DQ voltage detection value 923 from the simulated system power supply DQ voltage 922.

The simulated system current calculation means 910 calculates and outputs a simulated system current deviation 925 from the simulated system DQ voltage 924.
The PI control means 911 receives the simulated system current deviation 925 and outputs a PI control output DQ current command value 805 as a result of PI control.

  As shown in FIG. 10, in the subtracter 1001a, the simulated system current calculation means 910 converts the resistance value 1007 of the power system 111 from the simulated system DQ voltage 924 to the previous simulated system current calculated value 1006 held by the delay element 1005. Is subtracted from the voltage drop 1008 due to the resistance of the power supply system 111, thereby calculating the voltage drop 1009 due to the inductance of the power supply system 111.

  Next, the divider 1002 divides the voltage drop 1009 due to the inductance of the power supply system 111 by the inductance value 1010 of the power supply system 111 to obtain a value 1011 obtained by dividing the voltage drop due to the inductance of the power supply system 111 by the inductance of the power supply system 111. calculate. Next, the multiplier 1003b calculates the current change amount 1013 of the power supply system 111 by multiplying the value 1011 obtained by dividing the voltage drop due to the inductance of the power supply system 111 by the inductance of the power supply system 111 by the sampling time 1012.

  The integrator 1004 calculates the current calculation value 1014 of the power supply system 111 by integrating the current change amount 1013 of the power supply system 111. The subtractor 1001b outputs a simulated system current deviation 925 by subtracting the calculated current value 1014 of the power system 111 from the current command value 1015 of the power system 111. By setting the current command value 1015 of the power supply system 111 to zero, the capacitor voltage is controlled so as to control the simulated system current to zero.

(effect)
According to the power conversion device of this embodiment, the SMES power conversion device can be easily configured by using a plurality of single-phase bridge circuits. As a result, a low-cost power conversion device can be constructed and the reliability of the system can be improved. Further, since the direct current capacity is reduced, the current capacity and cost of the SMES coil and the cooling device can be reduced.

  Furthermore, the feedforward control using the detected value of the system current makes it possible to improve the transient response performance, and when the system interconnection device 209 is OFF, the overcurrent flows through the system or the load voltage decreases. Thus, it is possible to provide a SMES power conversion device for low voltage, high performance instantaneous voltage compensation. In addition, by providing the simulated system current control device 801, it is possible to smoothly switch between power supply by the power supply system 111 and power supply by the current source 110.

The circuit diagram which shows the power converter device of the 1st Embodiment of this invention. The circuit diagram which shows the power converter device of the 2nd Embodiment of this invention. The circuit diagram which shows the structure of the unit converter in the 2nd Embodiment of this invention. The figure which shows the structure and signal flow of a control apparatus in the 3rd Embodiment of this invention. The figure which shows the structure and signal flow of a capacitor voltage control apparatus in the 3rd Embodiment of this invention. The figure which shows the structure and signal flow of a current command control apparatus in the 3rd Embodiment of this invention. The figure which shows the structure and signal flow of the structure (equivalent to 1) of the PWM control apparatus in the 3rd Embodiment of this invention. The figure which shows the structure and signal flow of a control apparatus in the 4th Embodiment of this invention. The figure which shows the structure and signal flow of the simulation system current control apparatus in the 4th Embodiment of this invention. The figure which shows the structure and signal flow of the simulation system | strain electric current calculation means in the 4th Embodiment of this invention. The circuit diagram which shows the structure of the conventional power converter device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Unit converter, 2 ... Transformer, 101 ... Power converter, 102 ... Unit converter, 103 ... Capacitor, 104 ... Transformer, 105 ... Control apparatus, 106 ... Voltage detection apparatus, 107 ... Voltage detection apparatus, 108 DESCRIPTION OF SYMBOLS ... Current detection apparatus, 109 ... Grid connection apparatus, 110 ... Current source, 111 ... Power supply system, 112 ... Load, 201 ... Power converter, 202 ... Unit converter, 203 ... Capacitor, 204 ... Three-turn transformer, 205 DESCRIPTION OF SYMBOLS ... Control apparatus, 206 ... Voltage detection apparatus, 207 ... Voltage detection apparatus, 208 ... Current detection apparatus, 209 ... System interconnection apparatus, 210 ... System line voltage detection signal, 211 ... System current detection signal, 212 ... Capacitor voltage detection Signal 301, diode 302, switching element 401, capacitor voltage controller 402, current command controller 403 PWM controller, 4 4 ... Three-phase capacitor voltage detection value, 405 ... Capacitor voltage control DQ current command value, 406 ... System current feedforward control DQ current command value, 407 ... Three-phase output current command, 408 ... U-phase first stage unit converter gate Signal: 409 ... U phase second stage unit converter gate signal, 410 ... V phase first stage unit converter gate signal, 411 ... V phase second stage unit converter gate signal, 412 ... W phase first stage unit converter Gate signal, 413 ... W-phase second stage unit converter gate signal, 501a, 501b, 501c, 501d ... Three-phase two-phase conversion means, 502 ... Capacitor voltage amplitude detection means, 503 ... Capacitor voltage amplitude control means, 504 ... System line voltage phase detection means, 505... Capacitor voltage phase control means, 506... Capacitor voltage command generation means, 507a, 507b, 507c. 508 ... Subtraction means 509 ... PI control means 511 ... 2-phase capacitor voltage signal 512 ... Capacitor voltage amplitude 513 ... Capacitor voltage amplitude command value 514 ... System phase voltage phase signal 515 ... Capacitor voltage phase command signal, 516 ... Three-phase capacitor voltage command value, 517 ... Two-phase capacitor voltage command value, 518 ... DQ capacitor voltage command value, 519 ... DQ capacitor voltage detection value, 520 ... DQ capacitor voltage deviation, 522 ... Instantaneous power failure occurrence signal, 523a, 523b, 523c ... primary delay filter, 524 ... capacitor voltage amplitude command filter output value, 525 ... adder, 526 ... instantaneous drop determination means, 600 ... DQ current command value, 601 ... limiter means, 602 ... vector limit means, 603 ... Minimum ON pulse width control means, 604 ... DQ two-phase conversion means, 605 ... Two-phase three-phase conversion means 606 ... Three-phase current command control means, 607 ... Limit DQ current command, 608 ... Vector limit DQ current command, 609 ... Minimum ON pulse width control DQ current command, 610 ... Two-phase current command, 612 ... For instantaneous drop compensation control Three-phase output current command, 613 ... Three-phase output current command for standby control, 701 ... First-stage converter PWM control device, 702 ... Second-stage converter PWM control device, 703 ... PWM signal generator, 704 ... NOT circuit 705 ... Polarity inversion circuit, 706 ... Carrier signal, 707 ... First stage converter U arm gate signal, 708 ... First stage converter V arm gate signal, 709 ... First stage converter X arm gate signal, 710 ... 1st stage converter Y arm gate signal, 711 ... carrier signal, 712 ... 2nd stage converter U arm gate signal, 713 ... 2nd stage converter V arm gate signal, 714 ... 2 stages Eye converter X arm gate signal, 715 ... Second stage converter Y arm gate signal, 801 ... Simulated system current control device, 802 ... Current command control device, 805 ... PI control output DQ current command value, 901 ... Between system lines Voltage phase detection means, 902a, 902b, 902c ... three-phase to two-phase conversion means, 903 ... capacitor voltage amplitude detection means, 904 ... capacitor voltage amplitude control means, 905 ... adder, 906 ... capacitor voltage phase control means, 907 ... simulation System three-phase voltage generation means, 908a, 908b ... two-phase DQ conversion means, 909 ... subtraction means, 910 ... simulated system current calculation means, 911 ... PI control means, 912 ... two-phase system line voltage phase signal, 913 ... system Line voltage phase signal, 914 ... Two-phase capacitor voltage signal, 915 ... Capacitor voltage amplitude, 917 ... Capacitor voltage amplitude command value, 918 ... Denser voltage phase signal, 919 ... Capacitor voltage phase command signal, 920 ... Simulated system power supply three-phase voltage command value, 921 ... Simulated system power supply two-phase voltage command value, 922 ... Simulated system power supply DQ voltage, 923 ... Capacitor DQ voltage detection value 924 ... Simulated system DQ voltage, 925 ... Simulated system current deviation, 927 ... Primary delay filter, 928 ... Capacitor voltage amplitude command filter output value, 1001a, 1001b ... Subtractor, 1002 ... Divider, 1003a, 1003b ... Multiplier , 1004 ... integrator, 1005 ... delay element, 1006 ... previous simulation system current calculation value, 1007 ... power system resistance value, 1008 ... voltage drop due to power system resistance, 1009 ... voltage drop due to power system inductance, 1010 ... Inductance value of power supply system, 1011 ... Voltage drop due to inductance of power supply system Value obtained by dividing the lower part by the inductance of the power supply system, 1012... Sampling time, 1013... Current change amount of the power supply system, 1014.

Claims (4)

A plurality of unit converters connected in series with each other and connected to a current source to convert the DC power supplied from the current source into one phase of three-phase AC power in two stages;
A capacitor connected to the output terminal of each unit converter;
A three-winding transformer having windings respectively connected to the two-stage capacitors corresponding to one phase of three-phase AC power and windings connected to one phase of the corresponding three-phase power supply system;
A voltage detection device for detecting the voltage of the three-phase AC power supply system;
A voltage detection device for detecting the voltage of each capacitor;
A current detection device for detecting a current of the three-phase AC power supply system;
A controller that stably controls the capacitor voltage even during a transition by feedforward control using the detected value of the system current and the capacitor voltage control when it is detected that an instantaneous drop has occurred in the power supply system,
The controller is
Capacitor voltage control as a result of capacitor voltage control by inputting the three-phase capacitor voltage detection value calculated by adding the voltage of the output capacitor of the two-stage unit converter constituting each phase and the voltage detection signal between system lines A capacitor voltage control device for outputting a DQ current command value;
A current command control device that inputs the capacitor voltage control DQ current command value and the system current feedforward control DQ current command value and outputs a three-phase output current command;
Input the three-phase output current command, three-phase U-phase first-stage unit converter gate signal, U-phase second-stage unit converter gate signal, three-phase V-phase first-stage unit converter gate signal, V-phase A PWM controller that outputs a second stage unit converter gate signal, a three-phase W phase first stage unit converter gate signal, and a W phase second stage unit converter gate signal to each unit converter. And
A power converter having a voltage sag compensation control function that stably supplies required power to a load for a predetermined time during a power sag. A plurality of unit converters connected in series with each other and connected to a current source to convert the DC power supplied from the current source into one phase of three-phase AC power in two stages;
A capacitor connected to the output terminal of each unit converter;
A three-winding transformer having windings respectively connected to the two-stage capacitors corresponding to one phase of three-phase AC power and windings connected to one phase of the corresponding three-phase power supply system;
A voltage detection device for detecting the voltage of the three-phase AC power supply system;
A voltage detection device for detecting the voltage of each capacitor;
A current detection device for detecting a current of the three-phase AC power supply system;
A control device that stably controls the capacitor voltage even during a transition by feedforward control using the detected value of the system current and capacitor voltage control when it is detected that an instantaneous drop has occurred in the power supply system,
The controller is
Inputs the three-phase capacitor voltage detection value, which is the value obtained by adding together the capacitor voltages between the same type of the output capacitor voltage of each unit converter, and outputs the PI control output DQ current command value as a result of simulated system current control A simulated system current control device,
A current command control device for inputting the PI control output DQ current command value and the system current detection signal and outputting a three-phase output current command;
Input the three-phase output current command, three-phase U-phase first-stage unit converter gate signal, U-phase second-stage unit converter gate signal, three-phase V-phase first-stage unit converter gate signal, V A PWM controller for outputting a phase second stage unit converter gate signal, a three-phase W phase first stage unit converter gate signal, and a W phase second stage unit converter gate signal to each unit converter; Have
A power converter having a voltage sag compensation control function that stably supplies required power to a load for a predetermined time during a power sag.   The power converter according to claim 1 or 2, wherein said unit converter is constituted by a single phase bridge circuit.   A superconducting power storage device comprising: the power conversion device according to any one of claims 1 to 3; and a SMES coil as the current source.

Images