Power conversion system

Abstract

To provide a power conversion system which performs current balance control on the basis of output voltage information without performing current detection, the power conversion system being operated by connecting a plurality of power converters in parallel.SOLUTION: A power conversion system comprises: at least two power converters in which AC outputs supplied from a DC power source are connected in parallel via a reactor or a transformer; a control device which controls the power converters on the basis of an output voltage command value; a load voltage detector for detecting a voltage of an AC load to which the AC outputs are connected; and a plurality of output voltage detectors for detecting output voltages of the power converters. The control device defines voltage information obtained from the load voltage detector as a phase reference, converts voltages detected by the output voltage detectors into reactive voltages in accordance with the phase reference and corrects an amplitude component and a phase component of the output voltage command value in accordance with the reactive voltages of the power converters.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present invention relate to a power conversion system. [Background technology]

[0002] In a power conversion system in which multiple power converters are connected in parallel, the output voltage is the same. Even if the transformer impedance is the same, the power converter may be unstable due to variations in the transformer impedance and the line impedance. The output current varies.

[0003] Conventional current balance control methods for multiple power converters include detecting the output current of the converters. A method has been proposed for balancing the output currents by using current information.

[0004] Specifically, the output current is converted into active and reactive current components, and the output is proportional to the reactive current component. The amplitude component of the output voltage command value is corrected, and the phase component of the output voltage or the output This is a method for achieving current balancing by correcting the output frequency reference. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-229701 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is that the current balance control that detects the output current of the converter is As the number of switches increases, the number of current detection points also increases, making the calculations in the control device more complex. A power conversion system that performs current balance control from output voltage information without current detection. to provide. [Means for solving the problem]

[0007] The power conversion system of the present embodiment is connected in parallel via a reactor or a transformer, At least two power converters that convert DC power supplied from a DC voltage source into AC power; A control device that controls the power converter based on a voltage command and the power converter are connected to the control device. a bus voltage detector for detecting a voltage of a bus connected to the power converter; An output voltage detector and the control device detect a phase based on a voltage obtained from the bus voltage detector. A signal is calculated, and the voltage detected by the output voltage detector is converted into a reactive voltage by the phase signal. and correcting an amplitude component and a phase component of the voltage command in accordance with the reactive voltage of the power converter. . [Brief description of the drawings]

[0008] [Figure 1] 1 is a circuit configuration diagram of a power conversion system according to a first embodiment. [Diagram 2] FIG. 2 is a configuration diagram of a control device according to the first embodiment. [Diagram 3] FIG. 11 is a configuration diagram of a correction amount calculation unit according to a second embodiment. [Figure 4] FIG. 13 is a configuration diagram of a correction amount calculation unit according to a third embodiment. [Diagram 5] FIG. 13 is a circuit configuration diagram of a power conversion system showing a modified example of the third embodiment. [Figure 6] FIG. 13 is a configuration diagram of a correction amount calculation unit showing a modified example of the third embodiment. [Figure 7] FIG. 13 is a configuration diagram of a correction amount calculation unit according to a fourth embodiment. [Figure 8] FIG. 13 is a configuration diagram of a correction amount calculation unit according to a fifth embodiment. [Figure 9] FIG. 13 is a configuration diagram of a correction amount calculation unit according to a sixth embodiment. [Figure 10] FIG. 13 is a configuration diagram of a control device according to a seventh embodiment. [Figure 11] FIG. 13 is a configuration diagram of a correction amount calculation unit according to the seventh embodiment. [Figure 12] FIG. 23 is a configuration diagram of a correction amount calculation unit according to the eighth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment for carrying out the invention will be described.

[0010] (First embodiment) A power conversion system according to a first embodiment will be described with reference to FIGS.

[0011] FIG. 1 is a circuit diagram of a power conversion system.

[0012] The power conversion system includes a first DC voltage source 1A, a second DC voltage source 1B, and a first power converter. A first power converter 2A, a second power converter 2B, a first transformer 3A, a second transformer 3B, and an AC A load 6, a first voltage detector 7A, a second voltage detector 7B, and a third voltage detector 7C. The control device 8 includes a first control device 8A and a second control device 8B.

[0013] The first DC voltage source 1A and the second DC voltage source 1B are connected to the first power converter 2A and the second power The first DC voltage source 1A and the second DC voltage source 1B each supply DC power. B can be anything that can supply DC power, such as a power storage system, Alternatively, the power supply may be configured to supply DC power from a power splitter, converter, or the like.

[0014] The first power converter 2A and the second power converter 2B are respectively connected to the first DC voltage source 1A and the second DC voltage source 2B. The first power converter 2 converts DC power supplied from the DC voltage source 1B into AC power. A, the second power converter 2B is connected in inverse parallel to the switching element The switching element is turned on and off based on a gate signal. This converts DC power into AC power.

[0015] The first power converter 2A and the second power converter 2B are connected to a first transformer 3A and a second transformer 3B. B are connected in parallel through the first and second lines, and further connected in parallel through the third line. In an actual AC circuit network, AC power is supplied to the AC load 6 through a circuit breaker. Although the circuitry includes a filter circuit and the like, their description is omitted here. The current load 6 may be connected to a power grid.

[0016] The first transformer 3A and the second transformer 3B are connected to the first power converter 2A and the second power converter 2B, respectively. The AC voltage output from the converter 2B is transformed and output. The third line has a line impedance (reactor), so The first line impedance 4A, the second line impedance 4B, the third line impedance Shown in number 5.

[0017] First voltage detector 7A (output voltage detector), second voltage detector 7B (output voltage detector) , and the third voltage detector 7C (bus voltage detector) respectively detect the voltage of the first line, the voltage of the second line, Detect the voltage of the first line and the voltage of the third line.

[0018] The first control device 8A and the second control device 8B control the first power converter 2A and the second power converter 2B, respectively. A circuit for controlling the power converter 2B. A first control device 8A and a second control device 8B The voltages detected by the first voltage detector 7A, the second voltage detector 7B, and the third voltage detector 7C are The detected voltage value is input, and the first gate signal 9A and the second gate signal 9B are generated based on the detected voltage value. Generates signal 9B.

[0019] The generated first gate signal 9A and second gate signal 9B are respectively a first power conversion The power converter 2A and the second power converter 2B are connected to the first power converter 2A and the second power converter 2B. The control circuit may include, for example, a processor and a The program is implemented by software or a combination of software and hardware. The combination of the input and output ports can be configured to achieve various functions.

[0020] Next, the control device of the first embodiment will be described.

[0021] FIG. 2 is a configuration diagram of the control device. The first control device 8A and the second control device 8B Since the basic configuration is the same, the second control device 8B will be described below.

[0022] The second control device 8B includes an amplitude detection unit 10, a PLL calculation unit 11, a first adder 13, and , a proportional control device 14, a second adder 15A, a third adder 15B, and a voltage command calculation unit 17, a PWM control unit 18, a first reactive voltage calculation unit 19A, and a second reactive voltage calculation unit 1 9B and a correction amount calculation unit 20.

[0023] The amplitude detection unit 10 receives the third voltage Vc detected by the third voltage detector 7C and detects A pressure amplitude signal is output.

[0024] The PLL calculation unit 11 receives the third voltage Vc detected by the third voltage detector 7C, A phase signal θ is output.

[0025] The first adder 13 calculates an effective voltage command Vdref12 to be output by the second power converter 2B. The difference between the voltage amplitude signal from the width detector 10 is output to the proportional controller 14. .

[0026] The proportional control device 14 performs a proportional operation on the output of the first adder 13 and outputs the proportional control result to the second adder 15A. The voltage command value is then output to the voltage command calculation unit 17 via the voltage command calculation unit 17.

[0027] The voltage command calculation unit 17 receives the output of the proportional control device 14 via the second adder 15A and the third The reactive voltage command Vqref via the adder 15B is input, and the AC A voltage signal is generated.

[0028] The PWM control unit 18 generates a second voltage command based on the AC voltage signal generated by the voltage command calculation unit 17. A gate signal which is a switching pattern for turning on and off the switching element of the force transducer 2B Outputs 9.

[0029] In the above configuration, the amplitude detection unit 10, the PLL calculation unit 11, the first adder 13, and the proportional The control device 14, the voltage command calculation unit 17, and the PWM control unit 18 are connected in parallel. When controlling power supply from multiple power converters to the same bus, the following is generally required: This is the configuration used.

[0030] In the second control device 8B, the effective voltage command Vdref to be output by the second power converter 2B and the The voltage Vc detected by the third voltage detector 7C is used as the voltage Vc calculated by the amplitude detector 10. The difference between the voltage amplitude signal and the third voltage detected by the third voltage detector 7C is proportional to the voltage amplitude signal. The voltage converter outputs a phase signal θ calculated by the PLL calculation unit 11 based on Vc. By generating an AC voltage signal to be output, it is possible to achieve phase synchronization of the output voltage.

[0031] Next, a configuration for current balance control of the power converter will be described.

[0032] The first reactive voltage calculation unit 19A calculates the second voltage Vb detected by the second voltage detector 7B. The phase signal θ calculated by the PLL calculation unit 11 is input, and the reactive voltage of the second power converter 2B is Calculate the following.

[0033] The second reactive voltage calculation unit 19B calculates the first voltage Va detected by the first voltage detector 7A. The phase signal θ calculated by the PLL calculation unit 11 is input, and the reactive voltage of the first power converter 2A is Calculate the following.

[0034] The correction amount calculation unit 20 calculates the reactive voltage of the second power converter 2B calculated by the first reactive voltage calculation unit 19A. and the reactive voltage of the first power converter 2A calculated by the second reactive voltage calculation unit 19B. For example, the first reactive voltage calculation The reactive voltage of the second power converter 2B calculated by the reactive voltage calculation unit 19A and the reactive voltage of the second power converter 2B calculated by the reactive voltage calculation unit 19B The reactive voltage of the first power converter 2A calculated in step (2) is corrected by multiplying the reactive voltage by a predetermined constant. Calculate the amount.

[0035] The correction amount calculated by the correction amount calculation unit 20 is input to a second adder 15A and a third adder 15B. is output.

[0036] The second adder 15A subtracts the output of the correction amount calculation unit 20 from the output of the proportional control device 14. Then, the effective voltage signal (amplitude component) is corrected by outputting the voltage command to the voltage command calculation unit 17. cormorant.

[0037] The third adder 15B subtracts the output of the correction amount calculation unit 20 from the reactive voltage command Vqref to obtain a current By outputting the result to the pressure command calculation unit 17, the reactive voltage signal (phase component) is corrected.

[0038] The voltage command calculation unit 17 performs PLL calculation using the output of the second adder 15A and the third adder 15B. Based on the output of the PWM control unit 11, an AC voltage signal is generated, and the PWM control unit 18 outputs a gate signal 9. To exert effort.

[0039] As described above, in the control device according to the first embodiment, the current output of the power converter having a large current output is A large reactive voltage is generated in the output voltage, and a small reactive voltage is generated in the output voltage of a power converter with a small current output. When a voltage is generated, the effective voltage signal (amplitude component) and the reactive voltage signal are generated based on this reactive voltage. Correction is performed for both the phase component and the phase component.

[0040] This makes it possible to correct the output voltage of each power converter according to the difference in reactive voltage. This makes it possible to balance the current without detecting the output current of the power converter. ,The difference between the reactive voltage and the active voltage becomes larger when the output current differs. Based on the reactive voltage, both the effective voltage signal (amplitude component) and the reactive voltage signal (phase component) are By correcting the difference, it is possible to perform efficient current balance control.

[0041] Next, a control device according to a second embodiment will be described.

[0042] FIG. 3 is a configuration diagram of the correction amount calculation unit of the control device. Since this is the same as the second control device 8B, detailed description thereof will be omitted.

[0043] The correction amount calculation section 20-2 includes a fourth adder 21 and a correction calculation section 22.

[0044] The fourth adder 21 receives the output of the first reactive voltage calculation unit 19A and the output of the second reactive voltage calculation unit 19 The output of B is input and the difference between each output is calculated.

[0045] The correction calculation unit 22 calculates a correction amount based on the output of the fourth adder 21, and outputs the second adder The result is output as a correction amount to a third adder 15A and a third adder 15B.

[0046] This allows the power converter with a large reactive voltage to reduce the output voltage and suppress the output current. In this way, a power converter with a small reactive voltage operates in such a way that it increases its output voltage and increases its output current. This allows current balancing without detecting the output current of the power converter. .

[0047] Next, a control device according to a third embodiment will be described.

[0048] FIG. 4 is a configuration diagram of the correction amount calculation unit of the control device. The second control device 8B is the same as the second control device 8B, so detailed description will be omitted. The same components as those in the correction amount calculation unit of the embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0049] The correction amount calculation unit 20-3 includes a fifth adder 23, a multiplier 24, a fourth adder 21, and a correction calculation unit 22.

[0050] The fifth adder 23 receives the output of the first reactive voltage calculation unit 19A and the output of the second reactive voltage calculation unit 19 The output of B is input and the sum of each output is calculated.

[0051] The multiplier 24 divides the output of the fifth adder 23 by the number of power converters to obtain the average reactive voltage. In FIG. 4, the number of power converters is set to 2, so the average value is calculated as 1 / 2.

[0052] The fourth adder 21 receives the output of the first reactive voltage calculation unit 19A and the output of the multiplier 24. , and calculate the difference between their outputs.

[0053] The correction calculation unit 22 calculates a correction amount based on the output of the fourth adder 21, and outputs the second adder The result is output as a correction amount to a third adder 15A and a third adder 15B.

[0054] FIG. 5 is a circuit configuration diagram of a power conversion system showing a modified example of the third embodiment. The same components as those in the power conversion system of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Omitted.

[0055] The power conversion system of FIG. 5 is different from the power conversion system of the first embodiment shown in FIG. 1, the difference is that a plurality of power converters are connected in parallel.

[0056] The first power converter 2A to the n-th power converter 2n each have the same configuration. The power conversion devices are connected in parallel.

[0057] FIG. 6 is a configuration diagram of a correction amount calculation unit of a control device showing a modified example of the third embodiment. The same components as those in the correction amount calculation unit of the third embodiment are indicated with the same reference numerals, and detailed explanations thereof will be omitted.

[0058] The correction amount calculation unit 20-31 includes a sixth adder 23-2, a second multiplier 24-2, and a fourth The adder 21 and the correction calculation unit 22 are provided.

[0059] The sixth adder 23-2 receives the output of the first reactive voltage calculation unit 19A or the output of the reactive power calculation unit 19 The outputs of n are input and the sum of each output is calculated.

[0060] The second multiplier 24-2 divides the output of the sixth adder 23-2 by the number of power converters. In FIG. 6, the number of power converters is n, and the average value of the reactive voltage is calculated as 1 / n. is.

[0061] The fourth adder 21 receives the output of the first reactive voltage calculation unit 19A and the output of the second multiplier 24-2. Forces are input and the difference between the outputs is calculated.

[0062] The correction calculation unit 22 calculates a correction amount based on the output of the fourth adder 21, and outputs the second adder The result is output as a correction amount to a third adder 15A and a third adder 15B.

[0063] This allows the power converter with a large reactive voltage to reduce the output voltage and suppress the output current. In this way, a power converter with a small reactive voltage operates in such a way that it increases its output voltage and increases its output current. The average reactive voltage of each power converter is used as the basis for comparison. Current balance control is possible not only when two converters are connected in parallel, but also when three or more converters are connected in parallel. become.

[0064] Next, a control device according to a fourth embodiment will be described.

[0065] FIG. 7 is a configuration diagram of the correction amount calculation unit of the control device. Since the second control device 8B is the same as the second control device 8B, detailed description will be omitted. The same components as those in the correction amount calculation unit of the embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0066] The correction amount calculation unit 20-4 includes a fifth adder 23, a multiplier 24, a fourth adder 21, It includes a correction calculation unit 22 and an output limit 25 .

[0067] The output limiter 25 receives the output of the correction calculation unit 22 and detects if the output exceeds a predetermined upper limit or lower limit. When the correction amount is to be calculated, it is limited to a predetermined value, and the correction amount of the second adder 15A and the third adder 15B is calculated. and output it.

[0068] This makes it possible to limit the signal output to the maximum value of the correction amount calculated from the rated current, etc. , overcorrection can be avoided.

[0069] Next, a control device according to a fifth embodiment will be described.

[0070] FIG. 8 is a configuration diagram of the correction amount calculation unit of the control device. Since the second control device 8B is the same as the second control device 8B, detailed description will be omitted. The same components as those in the correction amount calculation unit of the embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0071] The correction amount calculation unit 20-5 includes a fifth adder 23, a multiplier 24, a fourth adder 21, The device includes a dead zone 26, a correction calculation section 22, and an output limit 25.

[0072] The dead zone 26 is provided between the fourth adder 21 and the correction calculation unit 22. When the output of 1 is within the range of the specified upper and lower limits, it outputs 0. In other words, When the difference in the reactive voltage is small, zero is output, and the calculated value of the correction amount by the correction calculation unit 22 is also zero. B is output.

[0073] This allows the compensation calculation to function when the reactive voltage difference exceeds the set value. , without operating the current balance control at all times, This allows you to correct the distortion.

[0074] Next, a control device according to a sixth embodiment will be described.

[0075] FIG. 9 is a configuration diagram of the correction amount calculation unit of the control device. The details of the control device 8B are the same as those of the second control device 8B, so they will not be described in detail. The same components as those in the correction amount calculation unit of the embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0076] The correction amount calculation unit 20-6 includes a fifth adder 23, a multiplier 24, a fourth adder 21, It includes a dead band 26, a proportional controller 27, and an output limit 25.

[0077] The proportional controller 27 performs a proportional calculation based on the output of the fourth adder 21 to obtain the reactive voltage difference The correction amount proportional to the second adder 15A and the third adder 15B are calculated as Output.

[0078] This allows the output voltage of the power converter to be adjusted so as not to increase the reactive voltage difference. It becomes like this.

[0079] Next, a control device according to a seventh embodiment will be described.

[0080] FIG. 10 is a configuration diagram of the control device. The first control device 8A and the second control device 8B However, since the basic configuration is the same, the following description will be given as the control device 8-2. The same components as those in the control device of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0081] The control device 8-2 is different from the control device of the first embodiment shown in FIG. 8 is different.

[0082] The correction amount calculation unit 28 calculates the correction amount for the effective voltage signal (amplitude component) and the reactive voltage signal (phase component). The correction amounts for the second adder 15A and the third adder 15B are calculated. The result is output as the correction amount of the detector 15B.

[0083] FIG. 11 is a configuration diagram of a correction amount calculation unit of the control device. The same components as those in the calculation unit are indicated by the same reference numerals, and detailed explanations are omitted.

[0084] The correction amount calculation unit 28 includes a fifth adder 23, a multiplier 24, a fourth adder 21, and an insensitive A band 26, a first correction calculation unit 29A, a second correction calculation unit 29B, and a first output limit The first output limiter 30A and the second output limiter 30B.

[0085] The fifth adder 23 receives the output of the first reactive voltage calculation unit 19A and the output of the second reactive voltage calculation unit 19 The output of B is input and the sum of each output is calculated.

[0086] The multiplier 24 divides the output of the fifth adder 23 by the number of power converters to obtain the average reactive voltage. In FIG. 11, the number of power converters is set to 2, so the average value is set to 1 / 2.

[0087] The fourth adder 21 receives the output of the first reactive voltage calculation unit 19A and the output of the multiplier 24. , and calculate the difference between their outputs.

[0088] The dead zone 26 receives the output of the fourth adder 21 and detects the difference between a predetermined upper limit and a predetermined lower limit. When the input is in the range 0 to 100, the output is zero.

[0089] The first correction calculation unit 29A calculates the effective voltage signal (amplitude component) based on the output of the dead zone 26. The correction amount for the difference is calculated.

[0090] The second correction calculation unit 29B corrects the reactive voltage signal (phase component) based on the output of the dead zone 26. The correction amount for the difference is calculated.

[0091] The first output limiter 30A receives the output of the first correction calculation unit 29A and adjusts it to a predetermined upper limit value. When the lower limit is exceeded, the value is limited to a predetermined value and used as the correction amount of the second adder 15A. Output.

[0092] The second output limiter 30B receives the output of the second correction calculation unit 29B and adjusts it to a predetermined upper limit value. When the lower limit is exceeded, the value is limited to a predetermined value and used as the correction amount of the third adder 15B. Output.

[0093] This makes it possible to control the active voltage correction signal and the reactive voltage correction signal separately. Correction calculation and output limit suitable for active voltage correction, correction calculation and output limit suitable for reactive voltage calculation It is possible to apply the mitt.

[0094] Next, a control device according to an eighth embodiment will be described.

[0095] FIG. 12 is a block diagram of the correction amount calculation unit of the control device. This is the same as the control device 8-2, so detailed description will be omitted. The same components as those in the correction amount calculation unit of the embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0096] The correction amount calculation unit 28-2 includes a fifth adder 23, a multiplier 24, a fourth adder 21, A dead zone 26, a first proportional controller 31A, a second proportional controller 31B, and a first output limit The first output limiter 30A and the second output limiter 30B.

[0097] The first proportional controller 31A performs a proportional calculation based on the output of the dead zone 26, and calculates the reactive voltage. A correction amount proportional to the difference is calculated to calculate the correction amount for the effective voltage signal (amplitude component).

[0098] The second proportional controller 31B performs proportional calculation based on the output of the dead zone 26, and calculates the reactive voltage. A correction amount proportional to the difference is calculated to calculate the correction amount for the effective voltage signal (amplitude component).

[0099] This allows the effective voltage compensation signal and the reactive voltage compensation signal to be proportionally controlled separately, Proportional control and output limit suitable for reactive voltage calculation are applied. This makes it possible to adjust the output voltage of the power converter so as not to increase the difference in reactive voltage. You will be able to do it.

[0100] Although several embodiments of the present invention have been described, these embodiments are presented by way of example. These novel embodiments are not intended to limit the scope of the invention. It is possible to embody various forms, and various omissions may be made without departing from the spirit of the invention. These embodiments and modifications are within the scope and spirit of the invention. This invention is intended to be encompassed by the spirit and scope of the present invention as defined in the claims and their equivalents. [Explanation of symbols]

[0101] 1A…First DC voltage source 1B…Second DC voltage source 2A…First power converter 2B…Second power converter 3A…First transformer 3B…Second transformer 6…AC load 7A…First voltage detector 7B…Second voltage detector 7C…Third voltage detector 8A…First control device 8B...Second control device 10...Amplitude detection section 11...PLL calculation section 13...First adder 14...Proportional control device 15A…Second adder 15B…Third adder 17…Voltage command calculation section 18...PWM control unit 19A…First reactive voltage calculation section 19B…Second reactive voltage calculation unit 20…Correction amount calculation section 21...4th adder 22...Correction calculation section 23...5th adder 24...Multiplier 25…Output limit 26…Blind zone 27…Proportional controller 28…Correction amount calculation section 29A...First correction calculation unit 29B...Second correction calculation unit 30A…First output limit 30B…Second output limit 31A…First proportional controller 31B…Second proportional controller

Claims

1. They are connected in parallel via reactors or transformers and receive DC power from a DC voltage source. At least two power converters for converting to AC power; A control device that controls the power converter based on a voltage command; a bus voltage detector for detecting a voltage of a bus to which the power converter is connected; a plurality of output voltage detectors for detecting output voltages of the power converter; The control device calculates a phase signal based on the voltage obtained from the bus voltage detector, The voltage detected by the output voltage detector is converted into a reactive voltage by the phase signal, and the power converter Correcting the amplitude component and the phase component of the voltage command in accordance with the reactive voltage Power conversion systems.

2. In the case where there are two power converters, the difference between the reactive voltages of the respective power converters is The amplitude component and the phase component of the voltage command are corrected by the control device.

2. The power conversion system of claim 1.

3. The reactive voltage of each of the power converters is the average of the reactive voltages of all the power converters. The amplitude and phase components of the voltage command are corrected by the control device according to the difference from the average value.

2. The power conversion system of claim 1.

4. An output limit is set for the correction signal calculated by the control device to limit the correction signal within a set range. do The power conversion system of claim 1 .

5. A dead band is provided for the reactive voltage difference calculated by the control device. The power conversion system according to claim 2 or 3.

6. Proportional control is performed to correct the amplitude and phase components of the voltage command. The power conversion system of claim 1 .

7. The amplitude component and the phase component of the voltage command are individually corrected. It is characterized by The power conversion system of claim 1 .

8. The amplitude and phase components of the voltage command are proportionally controlled separately. It is characterized by controlling The power conversion system of claim 1 .

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