Power grid voltage unbalance suppression method and device based on static synchronous compensator

Abstract

The invention discloses a power grid voltage unbalance suppression method and device based on a static synchronous compensator, and relates to the technical field related to power grid control, and the method comprises the steps: collecting a three-phase voltage operation signal of a common connection point of a power grid through an input end of the static synchronous compensator; sequence component decoupling is carried out, and a positive sequence component, a negative sequence component and a zero sequence component are extracted; constructing a target sequence component characteristic value, carrying out voltage unbalance degree comparison, and obtaining a compensation current signal meeting the target sequence component characteristic value based on the error signal vector by adopting a weighted least square method; and the static synchronous compensator drives the inverter to perform compensation current signal injection to the power grid common connection point according to the compensation current signal so as to suppress voltage imbalance. The technical problems of slow dynamic response, insufficient compensation precision and weak anti-interference capability of voltage unbalance suppression in the prior art are solved, and the technical effects of quickly and accurately compensating the voltage unbalance of the power grid, improving the electric energy quality and enhancing the operation stability of the power grid are achieved.

Description

Technical Field

[0001] This application relates to the field of power grid control technology, specifically to a method and apparatus for suppressing power grid voltage imbalance based on a static synchronous compensator. Background Technology

[0002] With the large-scale grid connection of distributed renewable energy sources such as photovoltaics and wind power, the problem of voltage asymmetry at the point of common coupling (PCC) caused by grid faults or load imbalances is becoming increasingly prominent. This leads to output current imbalance and power fluctuations in grid-connected converters. Voltage imbalance causes additional losses and increased temperature rise in equipment such as transformers and motors, and may even trigger malfunctions of protection devices, seriously affecting the power quality and reliability of the grid. Although dynamic voltage restorers can alleviate voltage drops through series compensation, they are expensive and require coupling transformers to connect to the grid lines. While grid-connected converters can be connected in parallel at the PCC to provide voltage support, they significantly weaken active power output during compensation. Static synchronous compensators (SSCs) have become the preferred solution for addressing voltage imbalance at the PCC. However, existing SSC solutions cannot adequately suppress negative sequence voltage components, and their support capacity is insufficient when the grid voltage drops severely.

[0003] Therefore, current technologies suffer from problems such as slow dynamic response to voltage imbalance suppression, insufficient compensation accuracy, and weak anti-interference capability. Summary of the Invention

[0004] This application provides a method and apparatus for suppressing grid voltage imbalance based on a static synchronous compensator, which solves the technical problems of slow dynamic response, insufficient compensation accuracy, and weak anti-interference capability in the prior art. It achieves the technical effects of rapidly and accurately compensating for grid voltage imbalance, improving power quality, and enhancing grid operation stability.

[0005] This application provides a grid voltage imbalance suppression method based on a static synchronous compensator (Synchronous Compensator). The method includes: acquiring a three-phase voltage operating signal at the grid point of common coupling (PCC) through the input terminal of the Synchronous Compensator; decoupling the three-phase voltage operating signal by sequence components to extract positive-sequence, negative-sequence, and zero-sequence components; constructing a target sequence component feature value; comparing the voltage imbalance degree based on the target sequence component feature value and the positive-sequence, negative-sequence, and zero-sequence components; and using a weighted least squares method based on the error signal vector to obtain a compensation current signal that satisfies the target sequence component feature value. The Synchronous Compensator then drives an inverter connected to it to inject a compensation current signal into the PCC to suppress voltage imbalance, according to the compensation current signal.

[0006] This application also provides a grid voltage imbalance suppression device based on a static synchronous compensator (SRC). The device includes: a voltage operation signal acquisition module for acquiring three-phase voltage operation signals at the grid common coupling point through the input terminal of the SRC; a sequence component decoupling module for decoupling the three-phase voltage operation signals to extract positive-sequence, negative-sequence, and zero-sequence components; a compensation current signal acquisition module for constructing target sequence component feature values, comparing the voltage imbalance degree based on the target sequence component feature values ​​with the positive-sequence, negative-sequence, and zero-sequence components, and obtaining a compensation current signal that satisfies the target sequence component feature values ​​based on the error signal vector using a weighted least squares method; and a compensation current signal injection module for the SRC to drive an inverter connected to the SRC to inject a compensation current signal into the grid common coupling point according to the compensation current signal to suppress voltage imbalance.

[0007] The proposed method and apparatus for suppressing grid voltage imbalance based on a static synchronous compensator (SSC) involves acquiring the three-phase voltage operating signal at the grid's point of common coupling (PCC) through the input of the SSC; decoupling the signal by its sequence components to extract the positive, negative, and zero-sequence components; constructing target sequence component eigenvalues; comparing the voltage imbalance degree; and using a weighted least squares method based on the error signal vector to obtain a compensation current signal that satisfies the target sequence component eigenvalues. The SSC then drives an inverter to inject a compensation current signal into the PCC to suppress voltage imbalance. This method solves the technical problems of slow dynamic response, insufficient compensation accuracy, and weak anti-interference capability in existing technologies, achieving the technical effects of rapid and accurate compensation of grid voltage imbalance, improved power quality, and enhanced grid operational stability. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments of this disclosure will be briefly described below. Flowcharts are used in this application to illustrate the operations performed by the apparatus according to the embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, various steps can be processed in reverse order or simultaneously as needed. Furthermore, other operations can be added to these processes, or one or more steps can be removed from these processes.

[0009] Figure 1 A schematic flowchart of a grid voltage imbalance suppression method based on a static synchronous compensator provided in this application embodiment.

[0010] Figure 2 This is a schematic diagram of the structure of the component for suppressing voltage imbalance at the point of common coupling in the grid voltage imbalance suppression method based on a static synchronous compensator provided in the embodiments of this application.

[0011] Figure 3 A schematic diagram of the grid point of common coupling voltage in the grid voltage imbalance suppression method based on a static synchronous compensator provided in the embodiments of this application.

[0012] Figure 4 This is a schematic diagram illustrating the calculation of the positive and negative sequence components of voltage in the grid voltage imbalance suppression method based on a static synchronous compensator provided in the embodiments of this application.

[0013] Figure 5 A schematic diagram of the grid voltage imbalance suppression device based on a static synchronous compensator provided in this application embodiment.

[0014] Explanation of reference numerals in the attached diagram: Voltage operation signal acquisition module 10, sequence component decoupling module 20, compensation current signal acquisition module 30, and compensation current signal injection module 40. Detailed Implementation

[0015] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below.

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description of this application will be provided in conjunction with the accompanying drawings. The described embodiments should not be considered as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] In the following description, references to "some embodiments" describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same or different subsets of all possible embodiments and can be combined with each other without conflict. The terms "first" and "second" are used merely to distinguish similar objects and do not represent a specific ordering of objects. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or modules not explicitly listed or inherent to these processes, methods, products, or apparatuses. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only.

[0018] This application provides a method for suppressing grid voltage imbalance based on a static synchronous compensator, such as... Figure 1 As shown, the method includes:

[0019] Step S100: Acquire the three-phase voltage operating signal of the power grid common connection point through the input terminal of the static synchronous compensator.

[0020] Preferred, such as Figure 2 , 3 As shown, a Static Synchronous Compensator (SSC) is a reactive power compensation device. Its core components include a voltage source inverter, DC-side capacitors, AC-side connecting reactors / transformers, and control components. It boasts advantages such as fast response speed, high regulation accuracy, and dynamic compensation for reactive power and unbalanced current. It is widely used in voltage regulation, power factor correction, and unbalanced compensation. The SSC injects a controllable compensation current through the voltage source inverter, enabling more flexible regulation of the grid voltage and improving grid dynamic stability. The point of common coupling (PCC) is the electrical connection point between the SSC and the grid, typically the distribution bus or grid connection point. The voltage quality at this point directly affects the SSC's control strategy. The three-phase voltage operating signal at the PCC is acquired through the input terminal of the SSC, i.e., real-time voltage information of the grid is collected using voltage transformers or current transformers. This information mainly includes instantaneous three-phase voltage, fundamental voltage, harmonic components, and sequence components.

[0021] Step S200: Decouple the three-phase voltage operating signal by sequence components and extract the positive sequence component, negative sequence component and zero sequence component.

[0022] Preferably, the imbalance of three-phase voltage or current is usually manifested as unequal amplitude or phase asymmetry of the three phases. By using coordinate transformation or digital filtering to decouple the three-phase voltage operating signal into sequence components, the three-phase voltage signal is decomposed into positive sequence components, negative sequence components, and zero sequence components to characterize different imbalance characteristics. Among them, the positive sequence component represents the normal three-phase symmetrical component, with equal amplitudes and a phase difference of 120°, rotating in the ABC sequence, and is the main component of power transmission in the power grid; the negative sequence component reflects the unbalanced or reverse rotating component of the three-phase voltage, which may have unequal amplitudes and still have a phase difference of 120°, but the rotation direction is opposite to the positive sequence (ACB), usually caused by unbalanced loads or faults; the zero sequence component represents the in-phase component of the three-phase voltage, with the same amplitude and no phase difference, usually caused by grounding faults or three-phase asymmetry, and may not exist in a system without a neutral line.

[0023] Furthermore, such as Figure 4As shown, step S200 further includes the sequence component decoupling method including dual second-order generalized integral phase-locked loop (PLL) technology. Step S210 transforms the three-phase voltage operating signal to obtain α voltage signal and β voltage signal in the αβ coordinate system. Step S220 inputs the α voltage signal and β voltage signal into an orthogonal dual second-order generalized integrator for orthogonal differential to obtain an orthogonal output signal. Step S230 inputs the orthogonal output signal into a synchronous phase-locked loop module for frequency synchronization processing and then performs symmetrical component separation processing to extract the positive sequence component and negative sequence component. Step S240 sums and averages the three-phase voltage operating signal to obtain the zero sequence component.

[0024] Preferably, the sequence component decoupling method includes dual second-order generalized integral phase-locked loop (PLL) technology. This technology is a composite control algorithm combining dual second-order generalized integrators and an improved phase-locked loop. It is mainly used for precise synchronization of grid voltage / current, rapid separation of positive and negative sequence components, and high-precision frequency / phase tracking under harmonic and noise environments. The dual second-order generalized integrator consists of two parallel second-order generalized integrator (SOGI) units. SOGI-α processes the α-axis signal, and SOGI-β processes the β-axis signal, generating orthogonal components of the αβ-axis signals to form an orthogonal signal generator. The improved phase-locked loop uses the orthogonal signal output from the orthogonal signal generator as input and employs a negative sequence component elimination loop to suppress unbalanced disturbances.

[0025] Preferably, the acquired three-phase voltage operating signals are subjected to coordinate transformation, that is, the three-phase stationary coordinate system is converted into a two-phase stationary coordinate system to obtain α-axis voltage signals and β-axis voltage signals. The α-axis voltage signal is the component in phase with the A-phase voltage, and the β-axis voltage signal is the quadrature component synthesized from the B and C-phase voltages. The α-axis voltage signals and β-axis voltage signals are then input into a quadrature dual second-order generalized integrator for quadrature differential analysis. The input signals are filtered to determine the quadrature output signals, that is, two output signals that are in phase with the input signals and quadrature with the input signals, and the quadrature signals strictly maintain a 90° phase difference. Then, the quadrature output signals are input into a synchronous phase-locked loop module for frequency synchronization processing to accurately track the fundamental frequency of the power grid and provide a synchronous rotation angle, and then output a synchronous rotation reference signal after phase-locking.

[0026] Preferably, the orthogonal signals are further separated into positive and negative sequences based on the synchronous rotation angle. Specifically, the αβ signal is converted to a positive-sequence synchronous rotating coordinate system, and the DC component (positive-sequence voltage) is extracted through low-pass filtering. Similarly, the αβ signal is converted to a negative-sequence synchronous rotating coordinate system, and the DC component (negative-sequence voltage) is extracted through low-pass filtering. Finally, the three-phase voltage operating signals are summed and averaged to obtain the zero-sequence component, reflecting the common-mode component of the three-phase voltage, such as the neutral point offset caused by a ground fault. Theoretically, the zero-sequence component is zero. Through multi-stage signal processing and coordinate transformation, high-precision and rapid extraction of the grid voltage imbalance components is achieved.

[0027] Step S300: Construct target sequence component feature values, compare the voltage imbalance with the positive sequence component, negative sequence component and zero sequence component based on the target sequence component feature values, and use the weighted least squares method to obtain the compensation current signal that satisfies the target sequence component feature values ​​based on the error signal vector.

[0028] Step S300 further includes the following: the target sequence component feature value includes the expected positive sequence component value, the expected positive sequence component phase, the expected negative sequence component value, the expected negative sequence component phase, the expected zero sequence component value, and the expected zero sequence component phase; wherein the expected negative sequence component value, the expected negative sequence component phase, the expected zero sequence component value, and the expected zero sequence component phase are defined as zero.

[0029] Preferably, the target sequence component characteristic value refers to the ideal sequence component reference value set according to the power grid operation standard, which is used to guide the static synchronous compensator to generate accurate compensation current. It includes the expected positive sequence component value, the expected positive sequence component phase, the expected negative sequence component value, the expected negative sequence component phase, the expected zero sequence component value, and the expected zero sequence component phase. Among them, the expected positive sequence component value refers to the positive sequence voltage amplitude that the power grid voltage should reach under ideal balance conditions, which is usually the rated voltage, such as 220V or 380V; the expected positive sequence component phase refers to the ideal phase angle of the positive sequence voltage, usually with phase A as the reference, and phases B and C lagging by 120° respectively; the expected negative sequence component value is set to zero, which means that there should be no negative sequence component in the target power grid voltage, that is, the voltage imbalance should be completely eliminated; the expected negative sequence component phase is also set to zero, the negative sequence component itself needs to be completely suppressed, and the phase is meaningless; the expected zero sequence component value is set to zero, which means that there should be no zero sequence component in the target power grid voltage, such as the neutral point offset needs to be eliminated in a three-phase four-wire system; the expected zero sequence component phase is set to zero, the zero sequence component needs to be completely eliminated, and the phase does not need to be considered. By setting the expected values ​​of the negative sequence and zero sequence components to zero, the control target is used to completely eliminate voltage asymmetry, thereby achieving high-precision voltage imbalance compensation and restoring the power grid to a three-phase symmetrical state.

[0030] Preferably, the voltage imbalance is compared with the target sequence component eigenvalue and the positive, negative, and zero sequence components. Specifically, the real-time detected actual sequence components (positive, negative, and zero sequence) of the power grid are compared with the pre-set target sequence component eigenvalue. After root mean square calculation, the amplitudes of the positive and negative sequence components of the voltage are obtained. The voltage imbalance at the point of common coupling of the power grid is obtained using the amplitudes of the positive and negative sequence components, and a quantitative index of voltage imbalance is established to determine the error signal vector. Then, the weighted least squares method is used to obtain the compensation current signal that satisfies the target sequence component eigenvalue based on the error signal vector. That is, the coupling relationship of positive, negative, and zero sequence errors is processed simultaneously. According to the power grid operation requirements, priority is assigned to different sequence components. Then, the sequence component error is converted into an error vector in a rotating coordinate system, and the compensation current signal that satisfies the target sequence component eigenvalue is solved.

[0031] Further, step S300 also includes step S310, wherein the error signal vector is the difference between the target sequence component eigenvalue and the positive sequence component, negative sequence component, and zero sequence component; step S320, establishing a linear response model, the linear response model including the three-phase compensation current vector signal to be determined, the voltage response matrix of the target power grid, and the response error term; step S330, introducing a weighting coefficient matrix, the weighting coefficient matrix including positive sequence weighting coefficients, negative sequence weighting coefficients, and zero sequence weighting coefficients; step S340, based on the error signal vector, the weighting coefficient matrix, and the linear response model, using the weighted least squares method to solve for the compensation current, obtaining the compensation current signal.

[0032] Furthermore, step S330 also includes that the negative order weighting coefficients of the weighting coefficient matrix are greater than the positive order weighting coefficients, which are greater than the zero order weighting coefficients.

[0033] Preferably, the error signal vector is a quantified deviation between the current operating state of the power grid and the ideal target. That is, the error signal vector is the difference between the target sequence component characteristic value and the positive sequence component, negative sequence component, and zero sequence component. Specifically, the positive sequence error vector = expected positive sequence component - measured positive sequence component; the positive sequence deviation reflects the difference between the power grid voltage amplitude / phase and the rated value, such as the actual positive sequence voltage of 215V and the target of 220V. The negative sequence error vector = 0 - measured negative sequence component (the target is complete elimination); the negative sequence deviation directly reflects the degree of voltage imbalance, such as the need to completely cancel a 2% negative sequence voltage. The zero sequence error vector = 0 - measured zero sequence component (the target is complete elimination); the zero sequence deviation characterizes the neutral point potential shift, commonly seen during grounding faults in distribution systems. A linear response model is constructed using the three-phase compensation current vector signal to be determined, the voltage response matrix of the target power grid, and the response error term. The power grid voltage response matrix reflects the influence of the compensation current on the sequence component, determined by the power grid impedance characteristics. The response error term includes measurement noise, unmodeled dynamics, etc. Then, a weighting coefficient matrix is ​​introduced. This includes positive-order weighting coefficients, negative-order weighting coefficients, and zero-order weighting coefficients to distinguish the compensation priority of different order components, ω + These are the positive-order weighting coefficients, which are usually small. The positive order should be maintained rather than forced to zero. ω - ω and ω0 are negative sequence weighting coefficients, respectively, with larger values ​​to reflect the strong suppression requirement; the negative sequence weighting coefficient is greater than the positive sequence weighting coefficient, which is greater than the zero sequence weighting coefficient, in order to enhance the error suppression capability of the negative sequence component; finally, based on the error signal vector, the weighting coefficient matrix and the linear response model, the weighted least squares method is used to solve the compensation current, that is, by minimizing the weighted error to solve the optimal compensation current, the power quality control problem is transformed into a numerical calculation problem that can be solved in real time, and the accurate compensation current is obtained.

[0034] Furthermore, step S340 also includes step S341, constructing a weighted error objective function based on the error signal vector, the weighting coefficient matrix, and the linear response model; step S342, establishing a weighted least squares optimization model with the goal of minimizing the weighted error objective function; and step S343, solving the weighted least squares optimization model using the weighted least squares method to obtain the optimal three-phase compensation current command vector.

[0035] Preferably, a weighted error objective function is constructed by integrating the error signal vector, weighting coefficient matrix, and power grid response model to reflect the overall error of positive-sequence maintenance, negative-sequence elimination, and zero-sequence suppression, quantifying the comprehensive deviation between the current voltage state and the ideal target. Among them, the negative-sequence weighting coefficient is the largest, reflecting the strong suppression requirement for imbalance; the positive-sequence weighting coefficient is the second largest, depending on the grounding system requirements; and the zero-sequence weighting coefficient is the smallest, allowing for small fluctuations. Different optimization weights are assigned to different sequence components through the weighting coefficient matrix, and the actual impact of compensation current on voltage is reflected through a linear response model. Then, with minimizing the weighted error objective function as the optimization goal, a complete weighted least squares optimization model is established. Specifically, the optimization variable is the three-phase compensation current command, and the constraints are the physical laws implicit in the grid response matrix, such as the maximum current limit. The weighted least squares method is then used to numerically solve the optimization model, and the problem of minimizing the weighted error is solved using linear algebra methods to find the optimal current combination that minimizes the overall weighted error, i.e., the three-phase compensation current command vector. This vector includes the magnitude of the compensation current to be injected into each phase, the phase relationship of the compensation current relative to the grid voltage, and the dynamically changing current command waveform. This ensures excellent voltage imbalance suppression performance under complex grid environments, guaranteeing that the grid voltage quality meets requirements.

[0036] In step S400, the static synchronous compensator drives the inverter connected to the static synchronous compensator to inject a compensation current signal into the grid common coupling point according to the compensation current signal to suppress voltage imbalance.

[0037] Preferably, the static synchronous compensator suppresses voltage imbalance by injecting precisely controlled compensation current into the grid. Specifically, the static synchronous compensator generates a corresponding PWM pulse width modulation drive signal based on the three-phase compensation current command calculated by the weighted least squares method, and clarifies the characteristics of the compensation current that the inverter needs to output, including negative sequence compensation current, zero sequence compensation current and positive sequence adjustment current. The negative sequence compensation current is out of phase with the detected negative sequence voltage and is used to cancel the negative sequence component in the grid. The zero sequence compensation current is for neutral point imbalance in a three-phase four-wire system, and the positive sequence adjustment current is used to fine-tune the positive sequence voltage amplitude to the rated value.

[0038] Preferably, the connected voltage source inverter, based on the drive signal, converts the energy stored in the DC-side capacitor into a precisely synchronized AC current with dynamically adjustable amplitude and controllable harmonic spectrum through the rapid switching of power devices such as insulated-gate bipolar transistors. The injected compensation current neutralizes the negative-sequence current at the grid's point of common coupling (PCC), thus canceling out the original negative-sequence current in the grid and restoring voltage symmetry; it also performs zero-sequence path compensation, providing a return path for unbalanced current and eliminating neutral point offset; and it provides positive-sequence voltage support, improving voltage amplitude through reactive current regulation. This suppresses voltage imbalance, effectively protecting the normal operation of sensitive equipment, and simultaneously handles imbalance, harmonics, and voltage dips, thereby improving power quality and enhancing grid stability.

[0039] Furthermore, step S400 also includes step S410, updating the three-phase voltage operating signals of each grid common coupling point in the target grid in real time; step S420, analyzing whether the updated three-phase voltage operating signals meet the voltage balance condition, and if the voltage balance condition is met, stopping the injection of compensation current signals from the inverter to the target grid; step S430, wherein the voltage balance condition includes the positive sequence component, negative sequence component and zero sequence component of the abnormal grid common coupling point satisfying the target sequence component characteristic value.

[0040] Preferably, the static synchronous compensator continuously collects the three-phase voltage operating signals of each grid common coupling (PCC) in the target grid. High-speed sampling enables real-time data updates. The updated three-phase voltage operating signals are then analyzed to determine if they meet voltage balance conditions. These conditions include ensuring that the positive-sequence, negative-sequence, and zero-sequence components of the abnormal grid common coupling point meet the target sequence component characteristic values. Specifically, the positive-sequence component must simultaneously meet the following requirements: positive-sequence component compliance (measured positive-sequence voltage amplitude = target positive-sequence voltage value ± allowable deviation, phase difference meets three-phase symmetry requirements); negative-sequence component compliance (negative-sequence voltage content ≤ target threshold, negative-sequence phase angle stable within allowable range); and zero-sequence component qualification (zero-sequence voltage amplitude ≤ set limit). If the voltage balance conditions are met, the inverter stops injecting compensation current signals into the target grid, avoiding frequent switching and thus achieving precise and energy-saving voltage imbalance management, extending equipment lifespan.

[0041] In the above text, refer to Figure 1 A method for suppressing grid voltage imbalance based on a static synchronous compensator according to an embodiment of the present invention is described in detail. Next, reference will be made to... Figure 5 A grid voltage imbalance suppression device based on a static synchronous compensator according to an embodiment of the present invention is described.

[0042] The grid voltage imbalance suppression device based on a static synchronous compensator according to embodiments of the present invention is used to solve the technical problems of slow dynamic response, insufficient compensation accuracy, and weak anti-interference capability in the prior art, achieving the technical effects of rapid and accurate compensation of grid voltage imbalance, improving power quality, and enhancing grid operation stability. Figure 5 As shown, the grid voltage imbalance suppression device based on static synchronous compensator includes: a voltage operation signal acquisition module 10, a sequence component decoupling module 20, a compensation current signal acquisition module 30, and a compensation current signal injection module 40.

[0043] The voltage operation signal acquisition module 10 is used to acquire the three-phase voltage operation signal at the grid common connection point through the input terminal of the static synchronous compensator; the sequence component decoupling module 20 is used to decouple the three-phase voltage operation signal into sequence components and extract the positive sequence component, negative sequence component, and zero sequence component; the compensation current signal acquisition module 30 is used to construct the target sequence component feature value, compare the voltage imbalance with the positive sequence component, negative sequence component, and zero sequence component based on the target sequence component feature value, and use the weighted least squares method to obtain the compensation current signal that satisfies the target sequence component feature value based on the error signal vector; the compensation current signal injection module 40 is used by the static synchronous compensator to drive the inverter connected to the static synchronous compensator to inject the compensation current signal into the grid common connection point according to the compensation current signal to suppress voltage imbalance.

[0044] The specific configuration of the compensation current signal acquisition module 30 will be described in detail below. The compensation current signal acquisition module 30 further includes: the target sequence component characteristic value includes a desired positive sequence component value, a desired positive sequence component phase, a desired negative sequence component value, a desired negative sequence component phase, a desired zero sequence component value, and a desired zero sequence component phase; wherein, the desired negative sequence component value, the desired negative sequence component phase, the desired zero sequence component value, and the desired zero sequence component phase are defined as zero.

[0045] The specific configuration of the compensation current signal acquisition module 30 will be described in detail below. The compensation current signal acquisition module 30 further includes: wherein the error signal vector is the difference between the target sequence component eigenvalue and the positive sequence component, negative sequence component, and zero sequence component; establishing a linear response model, the linear response model including the three-phase compensation current vector signal to be determined, the voltage response matrix of the target power grid, and the response error term; introducing a weighting coefficient matrix, the weighting coefficient matrix including positive sequence weighting coefficients, negative sequence weighting coefficients, and zero sequence weighting coefficients; and using the weighted least squares method to solve for the compensation current based on the error signal vector, the weighting coefficient matrix, and the linear response model to obtain the compensation current signal.

[0046] The specific configuration of the compensation current signal acquisition module 30 will be described in detail below. The compensation current signal acquisition module 30 further includes: constructing a weighted error objective function based on the error signal vector, the weighting coefficient matrix, and the linear response model; establishing a weighted least squares optimization model with the objective of minimizing the weighted error objective function; and solving the weighted least squares optimization model using the weighted least squares method to obtain the optimal three-phase compensation current command vector.

[0047] The specific configuration of the compensation current signal acquisition module 30 will be described in detail below. The compensation current signal acquisition module 30 further includes: the negative-order weighting coefficients of the weighting coefficient matrix are greater than the positive-order weighting coefficients, which are greater than the zero-order weighting coefficients.

[0048] The specific configuration of the compensation current signal injection module 40 will be described in detail below. The compensation current signal injection module 40 further includes: real-time updating of the three-phase voltage operating signals at each grid common coupling point in the target grid; analyzing whether the updated three-phase voltage operating signals meet the voltage balance condition; if the voltage balance condition is met, stopping the injection of compensation current signals from the inverter into the target grid; wherein, the voltage balance condition includes the positive sequence component, negative sequence component, and zero sequence component of the abnormal grid common coupling point satisfying the target sequence component characteristic value.

[0049] The specific configuration of the sequence component decoupling module 20 will be described in detail below. The sequence component decoupling module 20 further includes: transforming the three-phase voltage operating signal to obtain an α voltage signal and a β voltage signal in the αβ coordinate system; inputting the α voltage signal and the β voltage signal into an orthogonal dual second-order generalized integrator for orthogonal differential processing to obtain an orthogonal output signal; inputting the orthogonal output signal into a synchronous phase-locked loop module for frequency synchronization processing and then performing symmetrical component separation processing to extract the positive-sequence component and the negative-sequence component; and performing summation and averaging processing on the three-phase voltage operating signal to obtain the zero-sequence component.

[0050] The grid voltage imbalance suppression device based on static synchronous compensator provided in the embodiments of the present invention can execute the grid voltage imbalance suppression method based on static synchronous compensator provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method.

[0051] Although this application makes various references to certain modules in the apparatus according to the embodiments of this application, any number of different modules can be used and run on user terminals and / or servers. The various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional unit are only for easy distinction between each other and are not intended to limit the scope of protection of this invention.

[0052] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for suppressing grid voltage imbalance based on a static synchronous compensator, characterized in that, The method includes: The three-phase voltage operating signal at the power grid's point of common coupling is acquired through the input terminal of the static synchronous compensator. The three-phase voltage operating signal is decoupled by sequence components to extract the positive sequence component, negative sequence component and zero sequence component; Construct target sequence component feature values, compare the voltage imbalance with the positive sequence component, negative sequence component and zero sequence component based on the target sequence component feature values, and use the weighted least squares method to obtain the compensation current signal that satisfies the target sequence component feature values ​​based on the error signal vector; The static synchronous compensator drives the inverter connected to the static synchronous compensator to inject a compensation current signal into the grid common coupling point in accordance with the compensation current signal to suppress voltage imbalance.

2. The grid voltage imbalance suppression method based on a static synchronous compensator as described in claim 1, characterized in that, Construct target sequence component feature values, which include expected positive sequence component value, expected positive sequence component phase, expected negative sequence component value, expected negative sequence component phase, expected zero sequence component value, and expected zero sequence component phase; The expected negative sequence component value, the expected negative sequence component phase, the expected zero sequence component value, and the expected zero sequence component phase are defined as zero.

3. The grid voltage imbalance suppression method based on a static synchronous compensator as described in claim 1, characterized in that, The method employs weighted least squares to obtain a compensation current signal that satisfies the target sequence component eigenvalue based on the error signal vector. include: Wherein, the error signal vector is the difference between the target sequence component feature value and the positive sequence component, negative sequence component and zero sequence component; A linear response model is established, which includes the three-phase compensation current vector signal to be determined, the voltage response matrix of the target power grid, and the response error term; A weighted coefficient matrix is ​​introduced, which includes positive-order weighted coefficients, negative-order weighted coefficients, and zero-order weighted coefficients; Based on the error signal vector, the weighted coefficient matrix, and the linear response model, the weighted least squares method is used to solve for the compensation current, and the compensation current signal is obtained.

4. The grid voltage imbalance suppression method based on a static synchronous compensator as described in claim 3, characterized in that, The compensation current signal is obtained by solving the weighted least squares method. The method includes: Based on the error signal vector, the weighting coefficient matrix, and the linear response model, a weighted error objective function is constructed. A weighted least squares optimization model is established with the objective of minimizing the weighted error objective function. The weighted least squares optimization model is solved using the weighted least squares method to obtain the optimal three-phase compensation current command vector.

5. The grid voltage imbalance suppression method based on a static synchronous compensator as described in claim 3, characterized in that, The negative order weighted coefficients of the weighted coefficient matrix are greater than the positive order weighted coefficients, which are greater than the zero order weighted coefficients.

6. The grid voltage imbalance suppression method based on a static synchronous compensator as described in claim 1, characterized in that, After driving the inverter connected to the static synchronous compensator to inject a compensation current signal to the grid point of common coupling, the method further includes: Real-time updates of the three-phase voltage operating signals at each grid common connection point in the target power grid; Analyze whether the updated three-phase voltage operating signal meets the voltage balance condition. If the voltage balance condition is met, stop injecting compensation current signal into the target grid from the inverter. The voltage balance condition includes the positive sequence component, negative sequence component, and zero sequence component of the abnormal power grid common connection point satisfying the target sequence component characteristic value.

7. The grid voltage imbalance suppression method based on a static synchronous compensator as described in claim 1, characterized in that, The three-phase voltage operating signal is decoupled using a sequence component decoupling method, which includes a dual second-order generalized integral phase-locked loop (PLL) technique. The method includes: The three-phase voltage operating signal is transformed to obtain the α voltage signal and β voltage signal in the αβ coordinate system; The α voltage signal and β voltage signal are input into an orthogonal dual second-order generalized integrator for orthogonal differential analysis to obtain an orthogonal output signal; The orthogonal output signal is input into the synchronous phase-locked loop module for frequency synchronization processing, and then symmetrical component separation processing is performed to extract the positive sequence component and the negative sequence component. The three-phase voltage operating signals are summed and averaged to obtain the zero-sequence component.

8. A grid voltage imbalance suppression device based on a static synchronous compensator, characterized in that, The apparatus is used to implement the grid voltage imbalance suppression method based on a static synchronous compensator as described in any one of claims 1 to 7, and the apparatus comprises: The voltage operation signal acquisition module is used to acquire the three-phase voltage operation signal at the power grid common connection point through the input terminal of the static synchronous compensator. The sequence component decoupling module is used to decouple the three-phase voltage operating signal by sequence components and extract the positive sequence component, negative sequence component and zero sequence component. The compensation current signal acquisition module is used to construct the target sequence component feature value, compare the voltage imbalance with the positive sequence component, negative sequence component and zero sequence component based on the target sequence component feature value, and use the weighted least squares method to obtain the compensation current signal that satisfies the target sequence component feature value based on the error signal vector. The compensation current signal injection module is used to drive the inverter connected to the static synchronous compensator to inject a compensation current signal into the grid common coupling point according to the compensation current signal to suppress voltage imbalance.

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