SVG interphase balance control method, device, equipment, medium and program product

Abstract

The application discloses an SVG phase-to-phase balance control method and device, equipment, medium and program product, relates to the SVG control technical field, and includes the following steps: determining three-phase feedforward power and three-phase DC voltage deviation control power of an SVG; the three-phase feedforward power is generated by interaction between grid voltage and SVG current, and the three-phase DC voltage deviation control power is determined according to the deviation between three-phase DC voltage of the SVG and the average value of three-phase voltage; based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power, three-phase total power to be controlled is determined; based on the three-phase total power to be controlled and zero sequence voltage action power, the zero sequence voltage is determined; the zero sequence voltage action power is generated by interaction between the zero sequence voltage and the SVG current, and the sum of the three-phase total power to be controlled and the zero sequence voltage action power is zero; the zero sequence voltage is superimposed on SVG modulation voltage, and the SVG is driven based on the superimposed SVG modulation voltage. The application can realize phase-to-phase voltage balance control of the SVG.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of SVG phase-to-phase balance control, and particularly relates to an SVG phase-to-phase balance control method, device, equipment, medium and program product. BACKGROUND

[0002] A static var generator (SVG) can provide dynamic reactive support for a power system to suppress voltage fluctuations of the power system and compensate for imbalance of the system. However, due to factors such as internal three-phase bridge arm differences and external grid differences, the SVG may have a phenomenon of unbalanced three-phase DC side voltage, which affects the stable operation of the SVG, and therefore, the three-phase voltage of the SVG needs to be balanced. SUMMARY

[0003] The main purpose of the present application is to provide an SVG phase-to-phase balance control method, device, equipment, medium and program product, which aims to solve the technical problem of unbalanced three-phase DC side voltage of the SVG.

[0004] To achieve the above purpose, the present application provides an SVG phase-to-phase balance control method, which comprises the following steps:

[0005] determining three-phase feedforward power and three-phase DC voltage deviation control power of a static var generator (SVG); the three-phase feedforward power is generated by interaction of grid voltage at a grid connection point of the SVG and SVG current, and the three-phase DC voltage deviation control power is determined by deviation of three-phase DC voltage of the SVG and average value of three-phase voltage;

[0006] determining three-phase total power to be controlled based on sum of the three-phase feedforward power and the three-phase DC voltage deviation control power;

[0007] determining zero sequence voltage of the SVG based on the three-phase total power to be controlled and zero sequence voltage action power; the zero sequence voltage action power is generated by interaction of zero sequence voltage and SVG current, and sum of the three-phase total power to be controlled and the zero sequence voltage action power is zero;

[0008] superimposing the zero sequence voltage on SVG modulation voltage, and driving the SVG based on the superimposed SVG modulation voltage.

[0009] In an embodiment, the three-phase feedforward power comprises first three-phase feedforward power and second three-phase feedforward power.

[0010] Before the step of determining three-phase feedforward power and three-phase DC voltage deviation control power of a static var generator (SVG), the method further comprises:

[0011] acquire grid voltage and SVG current; wherein the grid voltage comprises grid positive sequence voltage and grid negative sequence voltage, and the SVG current comprises SVG positive sequence current and SVG negative sequence current;

[0012] The step of determining the three-phase feedforward power of the static var generator SVG comprises:

[0013] determining a first three-phase feedforward power based on the grid positive sequence voltage and the SVG negative sequence current;

[0014] determining a second three-phase feedforward power based on the grid negative sequence voltage and the SVG positive sequence current.

[0015] In an embodiment, the step of determining the three-phase DC voltage deviation control power of the static var generator SVG comprises:

[0016] determining a voltage deviation value of the SVG three-phase DC voltage and the three-phase voltage average value;

[0017] inputting the voltage deviation value into a proportional-integral controller to obtain the three-phase DC voltage deviation control power.

[0018] In an embodiment, after the step of determining the zero sequence voltage of the SVG based on the three-phase total power to be controlled and the zero sequence voltage action power, the method further comprises:

[0019] adjusting the SVG current in the case that the zero sequence voltage reaches an extreme value.

[0020] In an embodiment, the step of determining that the zero sequence voltage reaches an extreme value comprises:

[0021] judging whether the amplitude difference between the SVG positive sequence current and the SVG negative sequence current is less than a preset threshold value;

[0022] determining that the zero sequence voltage reaches an extreme value in the case that the amplitude difference is less than the preset threshold value;

[0023] The step of adjusting the SVG current comprises:

[0024] adjusting the SVG positive sequence current and / or adjusting the SVG negative sequence current to make the amplitude difference greater than the preset threshold value.

[0025] In an embodiment, the method further comprises:

[0026] performing the step of determining the zero sequence voltage of the SVG based on the three-phase total power to be controlled and the zero sequence voltage action power in a preset working condition; wherein the preset working condition is grid voltage imbalance, grid low voltage drop, SVG absorbing grid negative sequence current, or SVG negative sequence current compensating grid voltage imbalance.

[0027] Furthermore, to achieve the above objectives, this application also proposes an SVG inter-phase equalization control device, which includes:

[0028] The first determining module is used to determine the three-phase feedforward power and the three-phase DC voltage deviation control power of the static var generator (SVG). The three-phase feedforward power is generated by the interaction between the grid voltage at the SVG connection point and the SVG current. The three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage.

[0029] The second determining module is used to determine the total three-phase power to be controlled based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power.

[0030] The zero-sequence voltage calculation module is used to determine the zero-sequence voltage of the SVG based on the total three-phase power to be controlled and the zero-sequence voltage applied power; wherein, the zero-sequence voltage applied power is generated by the interaction between the zero-sequence voltage and the SVG current, and the sum of the total three-phase power to be controlled and the zero-sequence voltage applied power is zero;

[0031] The SVG driver module is used to superimpose the zero-sequence voltage onto the SVG modulation voltage and drive the SVG based on the superimposed SVG modulation voltage.

[0032] In addition, to achieve the above objectives, this application also proposes an SVG phase-to-phase equalization control device, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the SVG phase-to-phase equalization control method as described above.

[0033] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the SVG phase-to-phase equalization control method described above.

[0034] In addition, to achieve the above objectives, this application also proposes a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the SVG phase-to-phase equalization control method described above.

[0035] One or more technical solutions proposed in this application have at least the following technical effects:

[0036] In the SVG phase-to-phase equalization control method proposed in this application, the total three-phase power to be controlled can be determined by the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power. The three-phase feedforward power is generated by the interaction between the grid voltage and SVG current at the SVG grid connection point, reflecting the power difference caused by grid imbalance. The three-phase DC voltage deviation control power is determined by the deviation between the SVG's three-phase DC voltage and the average three-phase voltage, reflecting the SVG's steady-state error. Then, the zero-sequence voltage is solved using the principle of power balance, ensuring that the zero-sequence voltage generated by the interaction between the SVG's zero-sequence voltage and SVG current exactly cancels out the total three-phase power to be controlled, thus eliminating the power deviation caused by grid power imbalance and system steady-state error. This ensures that the SVG's three-phase voltage can reach a balanced state after zero-sequence voltage regulation. The determined zero-sequence voltage is superimposed on the SVG modulation voltage, and the SVG is driven based on the superimposed SVG modulation voltage to achieve balanced control of the SVG's three-phase voltage. Attached Figure Description

[0037] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the main circuit structure for a star-connected direct-connected SVG.

[0040] Figure 2 This is a schematic diagram of the power module structure;

[0041] Figure 3 This is a flowchart illustrating an embodiment of the SVG phase-to-phase equalization control method of this application.

[0042] Figure 4 A schematic diagram of the zero-sequence voltage amplitude during two-phase low-voltage ride-through;

[0043] Figure 5 This is a schematic diagram of extreme value processing;

[0044] Figure 6 A schematic diagram illustrating the control principle of the SVG phase-to-phase equalization control method;

[0045] Figure 7 This is a schematic diagram of the simulated waveforms under a 0.2 pu two-phase voltage drop during a low-voltage ride-through fault.

[0046] Figure 8 A schematic diagram of the simulation waveform for zero-sequence voltage control under system imbalance compensation;

[0047] Figure 9 This is a schematic diagram of the module structure of the SVG phase-to-phase equalization control device according to an embodiment of this application;

[0048] Figure 10 This is a schematic diagram of the device structure of the hardware operating environment involved in the SVG phase-to-phase equalization control method in the embodiments of this application.

[0049] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0050] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0051] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0052] The main solution of this application embodiment is as follows: determine the three-phase feedforward power and three-phase DC voltage deviation control power of the static var generator (SVG); the three-phase feedforward power is generated by the interaction between the grid voltage at the SVG grid connection point and the SVG current, and the three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage; determine the total three-phase power to be controlled based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power; determine the zero-sequence voltage of the SVG based on the total three-phase power to be controlled and the zero-sequence voltage action power; wherein, the zero-sequence voltage action power is generated by the interaction between the zero-sequence voltage and the SVG current, and the sum of the total three-phase power to be controlled and the zero-sequence voltage action power is zero; superimpose the zero-sequence voltage onto the SVG modulation voltage, and drive the SVG based on the superimposed SVG modulation voltage.

[0053] SVG plays an increasingly important role in new energy sources, providing dynamic reactive power support to the power system, improving the power factor, smoothing voltage fluctuations, and compensating for system imbalances. In related technologies, large-capacity SVGs are generally connected to the grid using cascaded H-bridge modules, while in new energy applications, a star connection of the main circuit is typically used to meet technical and economic requirements. For example, Figure 1 The diagram shows the main circuit structure of a star-connected SVG. The three-phase main circuit of the SVG is connected to the power grid in a star configuration, and each phase arm of the SVG is composed of several cascaded power modules; for example... Figure 2 As shown, Figure 2 This is a schematic diagram of the power module structure. Each power module consists of an H-bridge power unit and a DC capacitor. Figure 1As shown, phase A bridge arm is formed by cascading power modules A1, A2...An; phase B bridge arm is formed by cascading power modules B1, B2...Bn; and phase C bridge arm is formed by cascading power modules C1, C2...Cn. Each phase bridge arm of the SVG is connected to the power grid through a corresponding reactor.

[0054] The three-phase bridge arm module capacitors of the aforementioned star-connected SVG are generally floating. Due to factors such as differences in the three-phase bridge arms inside the SVG or differences in the external power grid, the SVG is prone to three-phase DC side voltage imbalance (especially under asymmetrical faults, this imbalance will be more prominent), which will seriously affect the stable operation of the SVG. Therefore, it is necessary to balance the three-phase voltage of the SVG.

[0055] This application provides a solution that determines the total three-phase power to be controlled by summing the three-phase feedforward power and the three-phase DC voltage deviation control power. The three-phase feedforward power is generated by the interaction between the grid voltage and SVG current at the SVG grid connection point, reflecting the power difference caused by grid imbalance. The three-phase DC voltage deviation control power is determined by the deviation between the SVG's three-phase DC voltage and the average three-phase voltage, reflecting the SVG's own steady-state error. The zero-sequence voltage is then calculated using the principle of power balance, ensuring that the zero-sequence voltage generated by the interaction between the SVG's zero-sequence voltage and SVG current exactly offsets the total three-phase power to be controlled. This eliminates the power deviation caused by grid power imbalance and SVG steady-state error, ensuring that the SVG's three-phase voltage reaches a balanced state after zero-sequence voltage regulation. The determined zero-sequence voltage is then superimposed on the SVG modulation voltage, and the SVG is driven based on the superimposed modulation voltage, thereby achieving balanced control of the SVG's three-phase voltage.

[0056] It should be noted that the execution subject in this embodiment is an SVG phase equalization control device. This device can be a computing service device with data processing, network communication and program running functions, such as a personal computer, or an electronic device capable of realizing the above functions.

[0057] Based on this, embodiments of this application provide an SVG phase-to-phase equalization control method, referring to... Figure 3 , Figure 3 This is a flowchart illustrating an embodiment of the SVG phase-to-phase equalization control method of this application.

[0058] In this embodiment, the SVG phase-to-phase equalization control method may include steps S100~S400:

[0059] Step S100: Determine the three-phase feedforward power and the three-phase DC voltage deviation control power of the SVG; the three-phase feedforward power is generated by the interaction between the grid voltage and the SVG current at the SVG grid connection point, and the three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage.

[0060] Step S200: Determine the total three-phase power to be controlled based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power.

[0061] Step S300: Determine the zero-sequence voltage of the SVG based on the total three-phase power to be controlled and the zero-sequence voltage applied power; wherein, the zero-sequence voltage applied power is generated by the interaction between the zero-sequence voltage and the SVG current, and the sum of the total three-phase power to be controlled and the zero-sequence voltage applied power is zero.

[0062] In step S400, the zero-sequence voltage is superimposed on the SVG modulation voltage, and the SVG is driven based on the superimposed SVG modulation voltage.

[0063] Specifically, the three-phase feedforward power can quantify the power difference caused by the interaction between the grid voltage and the SVG current, reflecting the grid imbalance. The three-phase DC voltage deviation control power is determined by the deviation between the SVG's three-phase DC voltage and the average three-phase voltage, reflecting the SVG's own steady-state error. Therefore, the three-phase feedforward power and the three-phase DC voltage deviation control power can be determined, and their sum can be taken as the total three-phase power to be controlled by the SVG. This allows for a comprehensive consideration of the grid state and the SVG's own operating state, enabling precise quantification of power deviation.

[0064] In one feasible implementation, the three-phase feedforward power may include a first three-phase feedforward power and a second three-phase feedforward power; wherein, the first three-phase feedforward power is mainly generated by the interaction of the grid positive-sequence voltage and the SVG negative-sequence current; and the second three-phase feedforward power is generated by the interaction of the grid negative-sequence voltage and the SVG positive-sequence current. Therefore, the grid voltage and SVG current can be obtained before step S100; wherein, the grid voltage includes the grid positive-sequence voltage and the grid negative-sequence voltage, and the SVG current includes the SVG positive-sequence current and the SVG negative-sequence current. Thus, the first three-phase feedforward power can be determined based on the grid positive-sequence voltage and the SVG negative-sequence current; and the second three-phase feedforward power can be determined based on the grid negative-sequence voltage and the SVG positive-sequence current.

[0065] Specifically, voltage sensors and other devices can be used to collect the grid voltage at the SVG grid connection point, and the grid voltage can be separated into positive and negative sequences to obtain the positive sequence voltage. and grid negative sequence voltage To facilitate the calculation of feedforward power for each phase, the positive sequence voltage of the power grid can be calculated separately. and grid negative sequence voltage Perform dq transformation to obtain the positive sequence voltage of the power grid. dq components ( and and the negative sequence voltage of the power grid dq components ( and ).

[0066] Similarly, the output current of the SVG (i.e., the SVG current) can be collected using devices such as current sensors, and then the positive sequence current of the SVG can be analyzed separately. and SVG negative sequence current Perform dq transformation to obtain the SVG positive sequence current. dq components ( and and SVG negative sequence current dq components ( and Alternatively, the reference current command injected into the SVG can be used ( , , and The reference current command injected into the SVG is directly used as the dq component of the positive-sequence current and the dq component of the negative-sequence current of the SVG. Understandably, in SVG control, the reference current command is the input command to the SVG control system, guiding the SVG's output current. Ideally, the SVG control system can perfectly track the reference current command, in which case the SVG's output current should be completely consistent with the reference current. Therefore, to simplify the calculation process, the SVG's reference current command can be used as the dq component of the SVG's positive-sequence current. and ) and the dq component of the negative sequence current of SVG ( and ).

[0067] Based on this, the three-phase feedforward power generated by the interaction of grid voltage and SVG current is calculated. This three-phase feedforward power includes the first three-phase feedforward power generated by the interaction of grid positive-sequence voltage and SVG negative-sequence current, and the second three-phase feedforward power generated by the interaction of grid negative-sequence voltage and SVG positive-sequence current; wherein, the first three-phase feedforward power includes the first feedforward power of phase A, the first feedforward power of phase B, and the first feedforward power of phase C; the second three-phase feedforward power includes the second feedforward power of phase A, the second feedforward power of phase B, and the second feedforward power of phase C.

[0068] Specifically, the first three-phase feedforward power can be determined using Equation 1. Equation 1 is:

[0069]

[0070] in, This represents the first feedforward power of phase A. This is the first feedforward power for phase B. This is the first feedforward power for phase C. The d-axis component of the negative sequence current of the SVG. This represents the q-axis component of the negative sequence current of the SVG. The positive sequence voltage of the power grid is represented by its d-axis component. This represents the q-axis component of the positive sequence voltage of the power grid.

[0071] Using Equation 2, the second and third phase feedforward power is determined. Equation 2 is:

[0072]

[0073] in, This is the second feedforward power for phase A. This is the second feedforward power for phase B. This is the second feedforward power for phase C. The d-axis component of the positive sequence current of the SVG. This represents the q-axis component of the positive sequence current of the SVG. This represents the d-axis component of the negative sequence voltage of the power grid. This represents the q-axis component of the negative sequence voltage of the power grid.

[0074] In one feasible implementation, the step of determining the three-phase DC voltage deviation control power of the static var generator (SVG) in step S100 may specifically include: determining the voltage deviation value between the three-phase DC voltage and the average value of the three-phase voltage of the SVG; inputting the voltage deviation value into the proportional-integral controller to obtain the three-phase DC voltage deviation control power.

[0075] The three-phase DC voltage of the SVG can be acquired using devices such as voltage sensors. The three-phase DC voltage of the SVG includes the DC voltages of phases A, B, and C; the average value of the three-phase voltages is the average of the DC voltages of phases A, B, and C. For each phase DC voltage of the SVG, the difference between each phase DC voltage and the average value of the three-phase voltages is calculated to obtain the corresponding voltage deviation value; then, the voltage deviation value of each phase is input into a proportional-integral controller to calculate the corresponding DC voltage deviation control power to be adjusted.

[0076] Specifically, the three-phase DC voltage deviation control power can be determined using formula three. The three-phase DC voltage deviation control power includes the DC voltage deviation control power for phase A, phase B, and phase C. Formula three is:

[0077]

[0078] in, ; The power for controlling the DC voltage deviation of phase A. The power for controlling the DC voltage deviation of phase B. The power for controlling the DC voltage deviation of phase C. This is the DC voltage of phase A. This is the DC voltage of phase B. This is the DC voltage of phase C. This is the average value of the three-phase voltage; The proportional control coefficient of the proportional-integral controller. The integral control coefficient of the proportional-integral controller. For the Laplace operator.

[0079] After determining the three-phase feedforward power and the three-phase DC voltage deviation control power, they can be summed to obtain the total three-phase power to be controlled. That is, the total three-phase power to be controlled can be determined by the following formula four:

[0080]

[0081] in, The total power to be controlled for phase A. The total power to be controlled for phase B. The total power to be controlled for phase C.

[0082] Utilizing the principle of power balance, the total three-phase power to be controlled cancels out the zero-sequence voltage's effect power to determine the corresponding zero-sequence voltage. The zero-sequence voltage's effect power is generated by the interaction between the zero-sequence voltage and the SVG current. By adjusting the zero-sequence voltage, voltage fluctuations caused by imbalances in the power grid can be balanced. Therefore, the goal of making the sum of the total three-phase power to be controlled and the zero-sequence voltage's effect power zero is to use the zero-sequence voltage's effect power to offset the total three-phase power to be controlled corresponding to the grid and SVG deviations, thereby effectively regulating the SVG's three-phase voltage and achieving three-phase voltage balance.

[0083] Specifically, the zero-sequence voltage can be expressed as ;in, It is the zero-sequence voltage. The zero-sequence voltage is represented by its d-axis component. is the q-axis component of the zero-sequence voltage, and j is the imaginary unit.

[0084] The zero-sequence voltage effect power is mainly generated by the interaction of the zero-sequence voltage and the SVG current. Similar to the determination of the three-phase feedforward power mentioned above, the SVG current can include both the positive-sequence SVG current and the negative-sequence SVG current. Correspondingly, the zero-sequence voltage effect power includes the first zero-sequence voltage effect power generated by the interaction of the zero-sequence voltage and the positive-sequence SVG current, and the second zero-sequence voltage effect power generated by the interaction of the zero-sequence voltage and the negative-sequence SVG current. The first zero-sequence voltage effect power can be determined using Equation 5. Equation 5 is:

[0085]

[0086] in, The power applied by the first zero-sequence voltage of phase A. The power applied by the first zero-sequence voltage of phase B. This is the power applied by the first zero-sequence voltage of phase C.

[0087] The power applied by the second zero-sequence voltage can be determined using formula six. Formula six is:

[0088]

[0089] in, The power applied by the second zero-sequence voltage of phase A. The power applied by the second zero-sequence voltage of phase B. This is the power applied by the second zero-sequence voltage of phase C.

[0090] To achieve phase-to-phase equalization control of the SVG, the zero-sequence voltage generated by the interaction of the zero-sequence voltage and the SVG current can be reverse-coupled with the previously determined total three-phase power to be controlled, thus obtaining the zero-sequence voltage. That is, the zero-sequence voltage can be determined using the following formula (Formula 7):

[0091]

[0092] Therefore, the dq component of the zero-sequence voltage, as shown in Equation 8, can be obtained. Equation 8 is:

[0093]

[0094] The determined zero-sequence voltage is superimposed on the SVG modulation voltage. The SVG is then driven by the SVG modulation voltage after the zero-sequence voltage is superimposed, adjusting the power flow in each phase to achieve phase-to-phase balance. The previously obtained zero-sequence voltage can be converted into a time-domain expression: ;in, The phase-locked angle is the positive sequence voltage of the power grid.

[0095] Then Superimposed on the modulation fundamental frequency (SVG modulation voltage): ;in, The superimposed SVG modulation voltage. The voltage is for SVG modulation. Compared to triangular carrier waves, PWM (Pulse Width Modulation) signals can be generated to drive the switching devices in the H-bridge power unit of the SVG.

[0096] It is worth mentioning that since the zero-sequence voltage may have extreme values ​​(i.e., points that reach the maximum or minimum value), this will cause modulation distortion of the SVG modulation voltage after the zero-sequence voltage is superimposed, affecting the stable control of the SVG. Therefore, after step S300, it can be determined whether the zero-sequence voltage has extreme values; if it is determined that the zero-sequence voltage has extreme values, the SVG current is adjusted.

[0097] Specifically, as can be seen from the aforementioned formula eight, the denominator of the zero-sequence voltage calculation formula includes the square of the positive-sequence current amplitude of SVG minus the square of the negative-sequence current amplitude of SVG. Therefore, when the amplitude of the positive-sequence current of the SVG is close to that of the negative-sequence current of the SVG, the zero-sequence voltage may have an extreme value, which will cause the overall output voltage of the SVG to be too high and result in overmodulation. Therefore, optimization is required.

[0098] Taking two-phase low-voltage ride-through as an example, under different drop depths and initial reactive power conditions, if we assume that the negative sequence current reference value is proportional to the negative sequence voltage, and the direction is to absorb the negative sequence current to reduce the negative sequence voltage, we can obtain the following: Figure 4 The diagram shows the zero-sequence voltage amplitude. From... Figure 4 As can be seen from this, in the reactive current (reference) Figure 4 The reactive base value) and negative sequence current (reference) Figure 4 The calculated zero-sequence voltage exhibits extreme values ​​near the range of AC port voltages, requiring optimization. In one feasible implementation, it can be determined whether the amplitude difference between the SVG positive-sequence current and the SVG negative-sequence current is less than a preset threshold; if the amplitude difference is less than the preset threshold, an extreme value for the zero-sequence voltage is identified. If an extreme value for the zero-sequence voltage is identified, the SVG positive-sequence current and / or the SVG negative-sequence current can be adjusted so that the amplitude difference between them exceeds the preset threshold, thereby eliminating the risk of an extreme value for the zero-sequence voltage.

[0099] For example, when the zero-sequence voltage exhibits an extreme value, it can be handled as follows: Figure 5 The diagram shown illustrates the extreme value handling to adjust the positive sequence current of the SVG. and SVG negative sequence current This makes the positive sequence current of the SVG and SVG negative sequence current It can satisfy: The conditions are set to ensure that there can be a certain difference between the amplitude of the positive-sequence current and the amplitude of the negative-sequence current of the SVG; among which, , ; The preset threshold can be used to determine its appropriate range based on the engineering safety margin and actual working conditions.

[0100] Then, based on the adjusted SVG current and the aforementioned calculation formula eight, the corresponding zero-sequence voltage is calculated, and the newly determined zero-sequence voltage is superimposed on the SVG modulation voltage for SVG control. In this way, the three-phase voltage phase-to-phase balance control of the SVG can be achieved while eliminating the extreme value of the zero-sequence voltage.

[0101] Furthermore, under preset operating conditions, the aforementioned step of determining the zero-sequence voltage of the SVG based on the total power to be controlled in three phases and the zero-sequence voltage action power can be executed; wherein, the preset operating conditions are grid voltage imbalance, grid low voltage drop, SVG absorbing grid negative-sequence current, or SVG negative-sequence current compensating for grid voltage imbalance. That is, the SVG phase-to-phase equalization control method in this embodiment can be used when the grid voltage contains positive and negative sequence voltages, such as when the grid voltage is slightly unbalanced, or when there is a symmetrical or asymmetrical low voltage drop; it is also applicable when the SVG output current contains positive and negative sequence currents, such as when the SVG needs to absorb grid negative-sequence current, or when the SVG needs to use negative-sequence current to compensate for grid voltage imbalance.

[0102] It is not difficult to understand that the SVG phase-to-phase equalization control method provided in this application can determine the total three-phase power to be controlled by the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power. Among them, the three-phase feedforward power is generated by the interaction between the grid voltage and the SVG current at the SVG grid connection point, which can reflect the power difference caused by grid imbalance. The three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage, which can reflect the steady-state error of the SVG. Then, the zero-sequence voltage is solved by the principle of power balance, so that the zero-sequence voltage generated by the interaction between the SVG zero-sequence voltage and the SVG current can just offset the total three-phase power to be controlled, that is, eliminate the power deviation caused by grid power imbalance and system steady-state error, so as to ensure that the three-phase voltage of the SVG can reach a balanced state after the zero-sequence voltage is regulated. The determined zero-sequence voltage is superimposed on the SVG modulation voltage, and the SVG is driven based on the superimposed SVG modulation voltage to realize the equalization control of the SVG three-phase voltage.

[0103] For example, to help understand the implementation process of the SVG phase-to-phase equalization control method in this embodiment, please refer to... Figure 6 , Figure 6 A schematic diagram of the control principle of an SVG phase-to-phase equalization control method is provided, specifically:

[0104] grid voltage ( , and Phase-locked angle of the positive sequence voltage of the power grid The input is processed by the voltage positive and negative sequence decomposition module, which performs positive and negative sequence decomposition and dq transformation on the grid voltage to obtain... , , and ; The current reference command injected into the SVG ( , , and ) directly used as the dq component of the positive and negative sequence current of SVG ( , , and ).

[0105] Using the aforementioned calculation formulas one and two, the three-phase feedforward power is obtained ( , , , , and The DC voltage of each phase of the SVG ( , and ) respectively with the average value of the three-phase voltage Perform a difference operation and input the result to the PI controller for processing to obtain the three-phase DC voltage deviation control power. , and ).

[0106] The total power to be controlled in the three phases is determined by summing the three-phase feedforward power and the three-phase DC voltage deviation control power. , and Using the principle of power balance, the total power of the three phases to be controlled is made to cancel out the power of the zero-sequence voltage, and the corresponding zero-sequence voltage is obtained by solving the problem. and For the specific solution process, please refer to the aforementioned embodiment section.

[0107] Considering the influence of extreme values ​​in the zero-sequence voltage, further prediction and adjustment of zero-sequence voltage extreme values ​​can be performed. If extreme values ​​exist in the zero-sequence voltage, an adjustment command for the reference current is returned to adjust the SVG current. This ensures a certain difference between the amplitudes of the SVG positive-sequence current and the SVG negative-sequence current, keeping the calculated zero-sequence voltage within a reasonable range and preventing over-modulation of the SVG voltage. The zero-sequence voltage is then redefined based on the adjusted SVG current, and the redefined zero-sequence voltage (after eliminating extreme values) is used to... and SVG control is performed.

[0108] Depend on Figure 6 As shown in the schematic diagram of the control principle, this application employs a combination of feedforward power and DC voltage control power for SVG regulation, which can quickly achieve voltage balance between the three phases of the SVG and maintain stable operation. Furthermore, considering the extreme value phenomenon of zero-sequence voltage, a current optimization method is adopted to improve the adaptability of the zero-sequence voltage method.

[0109] The aforementioned SVG phase-to-phase balancing control method can be applied to various situations where the reference current command contains specific control objectives. Taking asymmetrical low-voltage fault ride-through as an example, according to the latest grid connection standard for photovoltaic power plants, the SVG needs to absorb negative sequence current to ensure that the voltage imbalance at the grid connection point does not increase. Therefore, a zero-sequence voltage method is required for phase-to-phase balancing. Figure 7 The simulated waveforms are for a 0.2 pu two-phase voltage drop during a low-voltage ride-through fault. Figure 7 From top to bottom, the following parameters represent the system voltage Vsys (V_sysa is the AC voltage output of phase A at the SVG grid connection point, V_sysb is the AC voltage output of phase B at the SVG grid connection point, and V_sysc is the AC voltage output of phase C at the SVG grid connection point), the SVG system current Isys (I_svga is the AC current output of phase A at the SVG grid connection point, I_svgb is the AC current output of phase B at the SVG grid connection point, and I_svgc is the AC current output of phase C at the SVG grid connection point), the SVG three-phase DC voltage Vcap (VdcA_Avg is the DC voltage of phase A, VdcB_Avg is the DC voltage of phase B, and VdcC_Avg is the DC voltage of phase C), and the current reference dq command Currets. Ref (in the figure, ipdo1 is the reference value of the positive sequence current d-axis component, iqpu is the optimized and adjusted reference value of the positive sequence current q-axis component, indo1 is the reference value of the negative sequence current d-axis component, and inqo1 is the reference value of the negative sequence current q-axis component), zero sequence voltage U0 (uzd is the zero sequence voltage d-axis component, and uzq is the zero sequence voltage q-axis component), and the three-phase modulation voltage Vref of SVG (Vcaref1 is the A-phase modulation voltage, Vcbref1 is the B-phase modulation voltage, and Vccref1 is the C-phase modulation voltage), from Figure 7As can be seen, when entering and exiting asymmetrical drops, the three-phase DC voltage fluctuation of the SVG is in the range of approximately 0.9~1.1 pu, and during the drop, its three-phase DC voltage remains around 1.0 pu, indicating that the method of this application has achieved a good phase-to-phase balancing effect.

[0110] Taking system imbalance compensation as an example, the SVG needs to output negative-sequence current according to the negative-sequence voltage component of the power grid. Alternatively, zero-sequence voltage can be used to achieve phase-to-phase balance of the SVG. The simulation waveform of zero-sequence voltage control under system imbalance compensation is shown below. Figure 8 As shown, Figure 8 The waveforms from top to bottom are: system voltage Vsys (V_sysa is the AC voltage of phase A output at the SVG grid connection point, V_sysb is the AC voltage of phase B output at the SVG grid connection point, and V_sysc is the AC voltage of phase C output at the SVG grid connection point), system current Isys (I_svga is the AC current of phase A output at the SVG grid connection point, I_svgb is the AC current of phase B output at the SVG grid connection point, and I_svgc is the AC current of phase C output at the SVG grid connection point), SVG three-phase DC voltage Vcap (VdcA_Avg is the DC voltage of phase A, VdcB_Avg is the DC voltage of phase B, and VdcC_Avg is the DC voltage of phase C), and current reference dq command Currets. Ref (ipdo1 is the reference value of the positive sequence current d-axis component, iqpu is the optimized and adjusted reference value of the positive sequence current q-axis component, indo1 is the reference value of the negative sequence current d-axis component, inqo1 is the reference value of the negative sequence current q-axis component), zero-sequence voltage U0 (uzd is the zero-sequence voltage d-axis component, uzq is the zero-sequence voltage q-axis component), and the three-phase modulation voltage Vref of SVG (Vcaref1 is the modulation voltage of phase A, Vcbref1 is the modulation voltage of phase B, Vccref1 is the modulation voltage of phase C), and the negative sequence voltage amplitude UampN1. Figure 8 It can be seen that the three-phase DC voltage fluctuation of SVG is in the range of 0.97~1.04 pu, indicating that the zero-sequence voltage can also play a good role in phase balancing when compensating for unbalanced voltage in the system.

[0111] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the SVG phase-to-phase equalization control method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0112] This application also provides an SVG phase-to-phase equalization control device, please refer to... Figure 9 The SVG phase-to-phase equalization control device includes:

[0113] The first determining module 10 is used to determine the three-phase feedforward power and the three-phase DC voltage deviation control power of the static var generator (SVG). The three-phase feedforward power is generated by the interaction between the grid voltage at the SVG connection point and the SVG current. The three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage.

[0114] The second determining module 20 is used to determine the total three-phase power to be controlled based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power;

[0115] The zero-sequence voltage calculation module 30 is used to determine the zero-sequence voltage of the SVG based on the total three-phase power to be controlled and the zero-sequence voltage applied power; wherein, the zero-sequence voltage applied power is generated by the interaction between the zero-sequence voltage and the SVG current, and the sum of the total three-phase power to be controlled and the zero-sequence voltage applied power is zero;

[0116] The SVG driver module 40 is used to superimpose the zero-sequence voltage onto the SVG modulation voltage and drive the SVG based on the superimposed SVG modulation voltage.

[0117] The SVG phase-to-phase equalization control device provided in this application, employing the SVG phase-to-phase equalization control method in the above embodiments, can solve the technical problem of unbalanced phase-to-phase voltage on the three-phase DC side of the SVG. Compared with related technologies, the beneficial effects of the SVG phase-to-phase equalization control device provided in this application are the same as those of the SVG phase-to-phase equalization control method provided in the above embodiments, and other technical features in the above SVG phase-to-phase equalization control device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0118] This application provides an SVG phase-to-phase equalization control device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the SVG phase-to-phase equalization control method in the above embodiment 1.

[0119] The following is for reference. Figure 10 The diagram illustrates a structural schematic of an SVG phase-to-phase equalization control device suitable for implementing embodiments of this application. The SVG phase-to-phase equalization control device in the embodiments of this application may include, but is not limited to, mobile terminals such as laptops and fixed terminals such as desktop computers. Figure 10 The illustrated SVG phase equalization control device is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0120] like Figure 10As shown, the SVG phase-to-phase equalization control device may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the SVG phase-to-phase equalization control device. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to the I / O interface 1006: input devices 1007 including, for example, a touchscreen, touchpad, keyboard, mouse, image sensor, microphone, accelerometer, gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), speaker, vibrator, etc.; storage devices 1003 including, for example, magnetic tape, hard disk, etc.; and communication devices 1009. Communication device 1009 allows the SVG phase-to-phase equalization control device to communicate wirelessly or wiredly with other devices to exchange data. Although the figures show SVG phase-to-phase equalization control devices with various systems, it should be understood that implementation or possession of all the systems shown is not required. More or fewer systems may be implemented alternatively.

[0121] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0122] The SVG phase-to-phase equalization control device provided in this application, employing the SVG phase-to-phase equalization control method in the above embodiments, can solve the technical problem of unbalanced phase-to-phase voltage on the three-phase DC side of the SVG. Compared with related technologies, the beneficial effects of the SVG phase-to-phase equalization control device provided in this application are the same as those of the SVG phase-to-phase equalization control method provided in the above embodiments, and other technical features in this SVG phase-to-phase equalization control device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0123] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0124] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0125] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the SVG phase-to-phase equalization control method in the above embodiments.

[0126] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0127] The aforementioned computer-readable storage medium may be included in the SVG phase-to-phase equalization control device; or it may exist independently and not be assembled into the SVG phase-to-phase equalization control device.

[0128] The aforementioned computer-readable storage medium carries one or more programs. When the aforementioned one or more programs are executed by the SVG phase-to-phase equalization control device, the SVG phase-to-phase equalization control device causes the SVG to: determine the three-phase feedforward power and the three-phase DC voltage deviation control power of the static var generator (SVG); the three-phase feedforward power is generated by the interaction between the grid voltage at the SVG grid connection point and the SVG current, and the three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage; determine the total three-phase power to be controlled based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power; determine the zero-sequence voltage of the SVG based on the total three-phase power to be controlled and the zero-sequence voltage action power; wherein the zero-sequence voltage action power is generated by the interaction between the zero-sequence voltage and the SVG current, and the sum of the total three-phase power to be controlled and the zero-sequence voltage action power is zero; superimpose the zero-sequence voltage onto the SVG modulation voltage, and drive the SVG based on the superimposed SVG modulation voltage.

[0129] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0130] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0131] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0132] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described SVG phase-to-phase equalization control method, which can solve the technical problem of phase-to-phase voltage imbalance on the three-phase DC side of the SVG. Compared with related technologies, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the SVG phase-to-phase equalization control method provided in the above embodiments, and will not be repeated here.

[0133] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the SVG phase-to-phase equalization control method described above.

[0134] The computer program product provided in this application can solve the technical problem of phase-to-phase voltage imbalance on the three-phase DC side of the SVG. Compared with related technologies, the beneficial effects of the computer program product provided in this application are the same as those of the SVG phase-to-phase equalization control method provided in the above embodiments, and will not be repeated here.

[0135] The above description is only a part of the embodiments of this application and does not limit the scope of protection. All equivalent structural transformations made under the technical concept of this application and using the content of this application specification and drawings, or direct / indirect applications in other related technical fields, are included within the scope of protection.

Claims

1. An SVG phase-to-phase equalization control method, characterized in that, The SVG phase-to-phase equalization control method includes: The three-phase feedforward power and three-phase DC voltage deviation control power of the static var generator (SVG) are determined; the three-phase feedforward power is generated by the interaction between the grid voltage and the SVG current at the SVG grid connection point, and the three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage. The total power to be controlled for the three phases is determined based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power. Based on the total three-phase power to be controlled and the zero-sequence voltage applied power, the zero-sequence voltage of the SVG is determined; wherein, the zero-sequence voltage applied power is generated by the interaction of the zero-sequence voltage and the SVG current, and the sum of the total three-phase power to be controlled and the zero-sequence voltage applied power is zero; the zero-sequence voltage applied power includes the first zero-sequence voltage applied power generated by the interaction of the zero-sequence voltage and the positive-sequence current of the SVG and the second zero-sequence voltage applied power generated by the interaction of the zero-sequence voltage and the negative-sequence current of the SVG. The zero-sequence voltage is superimposed on the SVG modulation voltage, and the SVG is driven based on the superimposed SVG modulation voltage; After the step of determining the zero-sequence voltage of the SVG based on the total power to be controlled in the three phases and the zero-sequence voltage applied power, the method further includes: If the zero-sequence voltage is determined to have an extreme value, the SVG current is adjusted; The step of determining that the zero-sequence voltage has an extreme value includes: Determine whether the amplitude difference between the positive-sequence current and the negative-sequence current of the SVG is less than a preset threshold. If the amplitude difference is less than a preset threshold, it is determined that the zero-sequence voltage has an extreme value; The step of adjusting the SVG current includes: Adjust the positive sequence current of the SVG and / or adjust the negative sequence current of the SVG until the amplitude difference is greater than a preset threshold. The first zero-sequence voltage applied power is determined by calculation formula five, which is: ;in, The power applied by the first zero-sequence voltage of phase A. The power applied by the first zero-sequence voltage of phase B. The power applied by the first zero-sequence voltage of phase C; The d-axis component of the positive sequence current of the SVG. This represents the q-axis component of the positive sequence current of the SVG. The zero-sequence voltage is represented by its d-axis component. This represents the q-axis component of the zero-sequence voltage. The second zero-sequence voltage applied power is determined by calculation formula six, which is: ;in, The power applied by the second zero-sequence voltage of phase A. The power applied by the second zero-sequence voltage of phase B. The power applied by the second zero-sequence voltage of phase C; The d-axis component of the negative sequence current of the SVG. The q-axis component of the negative sequence current of the SVG; The zero-sequence voltage is determined by calculation formula eight, which is: ;in, The total power to be controlled for phase A. ; The total power to be controlled for phase B. ; The total power to be controlled for phase C. .

2. The SVG phase-to-phase equalization control method as described in claim 1, characterized in that, The three-phase feedforward power includes the first three-phase feedforward power and the second three-phase feedforward power; Before the step of determining the three-phase feedforward power and three-phase DC voltage deviation control power of the static var generator (SVG), the method further includes: Obtain the grid voltage and SVG current; wherein the grid voltage includes the grid positive-sequence voltage and the grid negative-sequence voltage, and the SVG current includes the SVG positive-sequence current and the SVG negative-sequence current; The steps for determining the three-phase feedforward power of the static var generator (SVG) include: The first three-phase feedforward power is determined based on the positive sequence voltage of the power grid and the negative sequence current of the SVG; The second three-phase feedforward power is determined based on the negative sequence voltage of the power grid and the positive sequence current of the SVG.

3. The SVG phase-to-phase equalization control method as described in claim 1, characterized in that, The steps for determining the three-phase DC voltage deviation control power of the static var generator (SVG) include: Determine the voltage deviation between the three-phase DC voltage of the SVG and the average value of the three-phase voltage; The voltage deviation value is input into the proportional-integral controller to obtain the three-phase DC voltage deviation control power.

4. The SVG phase-to-phase equalization control method as described in claim 1, characterized in that, The method further includes: Under preset operating conditions, the step of determining the zero-sequence voltage of the SVG based on the total power to be controlled in the three phases and the zero-sequence voltage action power is performed; wherein, the preset operating conditions are grid voltage imbalance, grid low voltage drop, SVG absorbing grid negative sequence current or SVG negative sequence current compensating for grid voltage imbalance.

5. An SVG phase-to-phase equalization control device, characterized in that, The SVG inter-phase equalization control device includes: The first determining module is used to determine the three-phase feedforward power and the three-phase DC voltage deviation control power of the static var generator (SVG); the three-phase feedforward power is generated by the interaction between the grid voltage at the SVG grid connection point and the SVG current, and the three-phase DC voltage deviation control power is determined by the deviation between the SVG three-phase DC voltage and the average value of the three-phase voltage. The second determining module is used to determine the total three-phase power to be controlled based on the sum of the three-phase feedforward power and the three-phase DC voltage deviation control power; The zero-sequence voltage calculation module is used to determine the zero-sequence voltage of the SVG based on the total three-phase power to be controlled and the zero-sequence voltage applied power; wherein, the zero-sequence voltage applied power is generated by the interaction of the zero-sequence voltage and the SVG current, and the sum of the total three-phase power to be controlled and the zero-sequence voltage applied power is zero; the zero-sequence voltage applied power includes a first zero-sequence voltage applied power generated by the interaction of the zero-sequence voltage and the positive-sequence current of the SVG and a second zero-sequence voltage applied power generated by the interaction of the zero-sequence voltage and the negative-sequence current of the SVG; An SVG driving module is used to superimpose the zero-sequence voltage onto the SVG modulation voltage and drive the SVG based on the superimposed SVG modulation voltage; The SVG phase-to-phase equalization control device is further configured to adjust the SVG current when the zero-sequence voltage is determined to have an extreme value; determine whether the amplitude difference between the SVG positive-sequence current and the SVG negative-sequence current is less than a preset threshold; determine that the zero-sequence voltage has an extreme value when the amplitude difference is less than the preset threshold; and adjust the SVG positive-sequence current and / or adjust the SVG negative-sequence current until the amplitude difference is greater than the preset threshold. The first zero-sequence voltage applied power is determined by calculation formula five, which is: ;in, The power applied by the first zero-sequence voltage of phase A. The power applied by the first zero-sequence voltage of phase B. The power applied by the first zero-sequence voltage of phase C; The d-axis component of the positive sequence current of the SVG. This represents the q-axis component of the positive sequence current of the SVG. The zero-sequence voltage is represented by its d-axis component. This represents the q-axis component of the zero-sequence voltage. The second zero-sequence voltage applied power is determined by calculation formula six, which is: ;in, The power applied by the second zero-sequence voltage of phase A. The power applied by the second zero-sequence voltage of phase B. The power applied by the second zero-sequence voltage of phase C; The d-axis component of the negative sequence current of the SVG. The q-axis component of the negative sequence current of the SVG; The zero-sequence voltage is determined by calculation formula eight, which is: ;in, The total power to be controlled for phase A. ; The total power to be controlled for phase B. ; The total power to be controlled for phase C. .

6. An SVG phase-to-phase equalization control device, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the SVG phase-to-phase equalization control method as described in any one of claims 1 to 4.

7. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the steps of the SVG phase-to-phase equalization control method as described in any one of claims 1 to 4.

8. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the steps of the SVG phase-to-phase equalization control method as described in any one of claims 1 to 4.

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