Energy storage converter compensation control method and system based on electric energy quality evaluation

Abstract

The embodiment of the invention relates to the technical field of intelligent compensation control, and provides an energy storage converter compensation control method and system based on electric energy quality assessment, and the method comprises the steps: firstly carrying out the comprehensive quantitative assessment of the electric energy quality of a grid-connected point, and precisely recognizing the severity of voltage deviation, harmonic waves, imbalance and other problems; then, on the basis of a multi-attribute utility theory, converting each electric energy quality index and an active task demand into a dynamic weight so as to scientifically quantify real-time urgency of different compensation tasks; and finally, carrying out optimal allocation on the limited capacity of the energy storage converter according to the dynamic weight system. Through the method, a compensation strategy can be converted from a fixed priority mode to a dynamic self-adaptive mode, and it is ensured that when the capacity of the energy storage converter is limited, the current most urgent electric energy quality problem is preferentially processed, so that the comprehensive compensation effect and the power grid supporting capacity of the energy storage system under the complex working condition are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of intelligent compensation control technology, and in particular to a compensation control method and system for energy storage converters based on power quality assessment. Background Technology

[0002] With the large-scale integration of renewable energy and the widespread application of power electronic equipment, modern power systems face increasingly severe power quality challenges. Voltage deviations, harmonic pollution, and three-phase imbalances not only affect the stable operation of the power grid but may also compromise the safety of user equipment. Energy storage systems, as a key component supporting the power grid, rely on their core component, the power storage converter (PCS), which possesses rapid and flexible regulation capabilities. In addition to performing basic active power tasks such as energy time-shifting, the PCS can also provide multiple ancillary services, including reactive power compensation, harmonic mitigation, and imbalance correction. Therefore, constructing an efficient PCS compensation and control scheme is of great significance for ensuring power grid security and improving power supply quality.

[0003] However, in actual operation, energy storage converters need to simultaneously handle active power dispatch commands and various power quality compensation demands, but their total capacity is limited. When the total demand for multi-dimensional tasks exceeds the rated capacity of the energy storage converter, a reasonable trade-off must be made among the various tasks. Existing compensation control strategies typically employ fixed priority schemes, such as "active power priority" or "reactive power priority," to allocate the limited capacity of the energy storage converter. However, this fixed strategy lacks flexibility and adaptability, and cannot dynamically adjust the compensation focus according to real-time changes in the grid state. For example, when the grid voltage deviates significantly, the fixed "active power priority" strategy may sacrifice necessary voltage support; and when harmonic problems are prominent, harmonic mitigation may not be prioritized. This leads to a significant reduction in the compensation effect of the energy storage converter, and its capacity resources are not effectively utilized to solve the most pressing power quality problems. Summary of the Invention

[0004] The present invention aims to solve at least one of the problems existing in the prior art, and provides a method and system for compensation control of energy storage converter based on power quality assessment.

[0005] One aspect of the present invention provides a compensation control method for an energy storage converter based on power quality assessment, the method comprising: Power quality indicators are decomposed into power quality metrics for the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the critical load to obtain a set of power quality metrics. The set of power quality metrics includes the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage unbalance. Multidimensional demand calculations are performed based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality measurement set to obtain the demand set, which includes the active power demand, reactive power compensation demand, apparent power demand for harmonic compensation, and apparent power demand for imbalance compensation. Dynamic weights are generated based on multi-attribute utility theory for the power quality measurement set, battery state of charge, and active power demand to obtain a dynamic weight set, which includes active weight, reactive weight, harmonic weight, and imbalance weight. Based on the dynamic weight set, the demand set is allocated according to the capacity constraints of the energy storage converter to obtain the instruction set. The instruction set includes the final active power instruction, the final fundamental reactive power instruction, the final harmonic compensation current instruction, and the final imbalance compensation current instruction. The instruction set is used to perform multi-functional compensation current synthesis and PWM signal generation to obtain the IGBT drive signal for the energy storage converter.

[0006] Optionally, the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the critical load are decomposed into power quality metrics to obtain a set of power quality measures, including: The three-phase instantaneous voltage at the PCC point is decomposed into grid voltage synchronization and symmetrical components to obtain the PCC voltage deviation rate, PCC voltage unbalance, and grid fundamental positive sequence voltage synchronization phase-locking angle. The load current harmonic decomposition and distortion rate calculation are performed on the synchronous phase-locked angle of the three-phase instantaneous current of the critical load and the fundamental positive sequence voltage of the power grid to obtain the total harmonic distortion rate of the load current.

[0007] Optionally, a multi-dimensional demand calculation is performed based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality metric set to obtain a demand set, including: Based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, the PCC voltage deviation rate, and the EMS active power command, the active power and fundamental frequency reactive power compensation demand is calculated to obtain the active power task demand and reactive power compensation demand. The apparent power demand for harmonic compensation is calculated based on the three-phase instantaneous voltage at point PCC and the three-phase instantaneous current of the critical load. The apparent power demand for unbalanced compensation is calculated based on the three-phase instantaneous voltage at the PCC point and the equivalent negative sequence impedance upstream of the grid.

[0008] Optionally, based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, the PCC voltage deviation rate, and the EMS active power command, the active power and fundamental frequency reactive power compensation demands are calculated to obtain the active power task demand and the reactive power compensation demand, including: The active power command of EMS is deconstructed into an active power task to obtain the active power demand of the task. Based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, and the PCC voltage deviation rate, the active power and fundamental frequency reactive power compensation demand are calculated using the following formula to obtain the reactive power compensation demand: ; ; in, PCC voltage deviation rate, This represents the voltage deviation error for the current control cycle. This represents the voltage deviation error from the previous control cycle. and These are integral gain and proportional gain, respectively. This is to meet the reactive power compensation requirements of the previous control cycle. This is for the reactive power compensation requirement of the current control cycle.

[0009] Optionally, a dynamic weight set is obtained by dynamically generating weights based on multi-attribute utility theory for the power quality metric set, battery state of charge, and active power demand, including: The power quality measurement set is transformed into utility to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation. The basic weight of the active task is calculated based on the battery state of charge and the power required by the active task. The basic weights of reactive power compensation, harmonic compensation, imbalance compensation, and active power task are aggregated and normalized to obtain a dynamic weight set.

[0010] Optionally, the power quality measurement set is subjected to utility transformation to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation, including: Input the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage imbalance into the general utility function to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation, respectively.

[0011] Optionally, the general utility function is expressed as: ; in, For general utility functions, This refers to the PCC voltage deviation rate, the total harmonic distortion rate of the load current, or the PCC voltage unbalance. for The corresponding normalized baseline value, for The corresponding risk aversion coefficient.

[0012] Optionally, the basic weights for reactive power compensation, harmonic compensation, imbalance compensation, and active power task are aggregated and normalized to obtain a dynamic weight set, including: The total basic weight value is obtained by adding the basic weights of reactive power compensation, harmonic compensation, imbalance compensation, and active power task. Divide the reactive power compensation base weight, harmonic compensation base weight, unbalanced compensation base weight, and active power task base weight by the total base weight value to obtain the corresponding active power weight, reactive power weight, harmonic weight, and unbalanced weight, respectively.

[0013] Optionally, based on a dynamic weight set, the demand set is allocated according to the capacity constraints of the energy storage converter to obtain an instruction set, including: A comprehensive demand aggregation and overload determination are performed on the demand set and the rated apparent power of the energy storage converter to obtain the fundamental apparent power demand, the total apparent power demand and the overload indicator. In response to the overload flag being true, the apparent power capacity of the demand set is allocated based on the dynamic weight set to obtain the apparent power allocated to the fundamental task, the apparent power allocated to harmonic compensation, and the apparent power allocated to unbalance compensation. The apparent power allocated to the fundamental wave task, the apparent power allocated to harmonic compensation, and the apparent power allocated to unbalance compensation are deconstructed and security-checked to obtain the instruction set.

[0014] Another aspect of the present invention provides a power quality assessment-based energy storage converter compensation control system, the power quality assessment-based energy storage converter compensation control system comprising: The power quality index decomposition module is used to decompose the power quality index of the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the key load to obtain a set of power quality metrics. The set of power quality metrics includes the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage unbalance. The multi-dimensional demand calculation module is used to perform multi-dimensional demand calculations based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality measurement set to obtain the demand set. The demand set includes the active task demand power, reactive power compensation demand power, harmonic compensation demand apparent power, and unbalance compensation demand apparent power. The dynamic weight generation module is used to generate dynamic weights based on the multi-attribute utility theory for the power quality measurement set, battery state of charge and active power demand to obtain a dynamic weight set. The dynamic weight set includes active weight, reactive weight, harmonic weight and unbalance weight. The PCS capacity constraint allocation module is used to allocate the demand set based on dynamic weights to the energy storage converter capacity constraint to obtain the instruction set. The instruction set includes the final active power instruction, the final fundamental reactive power instruction, the final harmonic compensation current instruction, and the final imbalance compensation current instruction. The PWM signal generation module is used to perform multi-functional compensation current synthesis and PWM signal generation on the instruction set to obtain the IGBT drive signal of the energy storage converter.

[0015] Compared to existing technologies, this invention first comprehensively and quantitatively assesses the power quality at the grid connection point, accurately identifying the severity of issues such as voltage deviation, harmonics, and imbalance. Next, based on multi-attribute utility theory, it transforms various power quality indicators and active power requirements into dynamic weights, thereby scientifically quantifying the real-time urgency of different compensation tasks. Finally, it optimally allocates the limited capacity of the energy storage converter according to this dynamic weighting system. This method enables a shift in compensation strategy from a fixed priority mode to a dynamic adaptive mode, ensuring that when the capacity of the energy storage converter is limited, the most urgent power quality issues are addressed first, thus significantly improving the overall compensation effect and grid support capability of the energy storage system under complex operating conditions. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with the corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0017] Figure 1 A flowchart of a power storage converter compensation control method based on power quality assessment provided in one embodiment of the present invention; Figure 2 A schematic diagram of data flow for a power storage converter compensation control method based on power quality assessment, provided for another embodiment of the present invention; Figure 3This is a block diagram of an energy storage converter compensation control system based on power quality assessment, provided as another embodiment of the present invention. Detailed Implementation

[0018] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention; it should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0019] As indicated in the specification and claims of this invention, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0020] While this invention makes various references to certain modules in systems according to embodiments of the invention, any number of different modules can be used and run on user terminals and / or servers. The modules are merely illustrative, and different aspects of the systems and methods may use different modules.

[0021] This invention uses flowcharts to illustrate the operations performed by the system according to embodiments of the invention. 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 them.

[0022] In the technical solution of this invention, a compensation control method for energy storage converters based on power quality assessment is proposed. Figure 1 This is a flowchart of a power storage converter compensation control method based on power quality assessment according to an embodiment of the present invention. Figure 2 This is a schematic diagram of data flow in an energy storage converter compensation control method based on power quality assessment according to an embodiment of the present invention. (In conjunction with...) Figure 1 and Figure 2According to an embodiment of the present invention, a power quality assessment-based energy storage converter compensation control method includes the following steps: S1, decomposing the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the critical load into power quality indicators to obtain a power quality metric set, the power quality metric set including the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage imbalance; S2, performing multi-dimensional demand calculation based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality metric set to obtain a demand set, the demand set including the active power demand, reactive power compensation demand, apparent power demand for harmonic compensation, and apparent power demand for imbalance compensation. S3. Calculate the apparent power; S4. Generate a dynamic weight set based on multi-attribute utility theory for the power quality metric set, battery state of charge, and active power demand. The dynamic weight set includes active power weight, reactive power weight, harmonic weight, and imbalance weight; S5. Based on the dynamic weight set, allocate the demand set to the energy storage converter capacity constraint based on the dynamic weight to obtain the command set. The command set includes the final active power command, the final fundamental reactive power command, the final harmonic compensation current command, and the final imbalance compensation current command; S6. Perform multi-functional compensation current synthesis and PWM signal generation on the command set to obtain the IGBT drive signal of the energy storage converter.

[0023] Specifically, in step S1, the instantaneous three-phase voltage at the PCC point and the instantaneous three-phase current of the critical load are decomposed into power quality indicators to obtain a set of power quality metrics. This set includes the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage imbalance. Since the instantaneous voltage and current waveforms contain complex information, direct use is difficult for control decisions. Therefore, they are decomposed into standardized power quality indicators with clear physical meaning, such as the voltage deviation rate, total harmonic distortion rate, and imbalance. This transforms the abstract power quality problem into specific, quantifiable values, enabling subsequent control algorithms to be executed accurately.

[0024] In its specific implementation, S1 first involves acquiring the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the critical load. The PCC point refers to the grid connection point of the energy storage system. The three-phase instantaneous voltage at the PCC point is obtained by connecting a high-precision voltage transformer (PT) installed at the PCC to the data acquisition system. This voltage directly reflects the power quality at the grid connection point and is a core indicator for evaluating grid voltage stability. The compensation effect of the energy storage converter is ultimately reflected in the improvement of the voltage at this point. The three-phase instantaneous current of the critical load is obtained through current transformers (CTs) installed on the feeders of the main nonlinear or impulsive loads. This current reveals the main sources of power quality problems, and analyzing it helps determine the specific objectives of compensation tasks such as harmonic mitigation.

[0025] Next, the instantaneous three-phase voltage at the PCC point is subjected to grid voltage synchronization and symmetrical component decomposition to obtain the PCC voltage deviation rate, PCC voltage unbalance, and grid fundamental positive sequence voltage synchronization phase-locked angle. During this process, techniques such as Synchronous Reference Coordinate System Phase-Locked Loop (SRF-PLL) are used to process the acquired three-phase voltage signals at the PCC point, accurately tracking the amplitude, frequency, and phase of the grid fundamental positive sequence voltage, thereby obtaining the grid fundamental positive sequence voltage synchronization phase-locked angle. Simultaneously, the symmetrical component method is used to decompose the three-phase unbalanced voltage into positive sequence, negative sequence, and zero sequence components. Based on these decomposition results, the PCC voltage deviation rate and PCC voltage unbalance can be accurately calculated. The PCC voltage deviation rate characterizes the stability level of the grid voltage; excessively high or low values ​​will affect the normal operation of electrical equipment and are an important basis for triggering reactive power compensation for voltage support. The PCC voltage imbalance reflects the symmetry of the three-phase voltage. A high imbalance can cause negative sequence current to be generated in motors and other equipment, increasing losses and even causing damage. Therefore, the PCC voltage imbalance is a key driving indicator for imbalance compensation tasks.

[0026] Furthermore, the load current harmonic decomposition and distortion rate calculation are performed on the instantaneous three-phase current of the key load and the synchronous phase-locked angle of the grid fundamental positive-sequence voltage to obtain the total harmonic distortion (THD) of the load current. That is, the grid fundamental positive-sequence voltage synchronous phase-locked angle obtained in the previous sub-process is used as a reference to process the acquired load current signal. Specifically, the current waveform in the time domain can be transformed to the frequency domain using a Fast Fourier Transform (FFT) algorithm to obtain the amplitude of the fundamental current and the amplitudes of each harmonic current. Based on the amplitudes of these harmonic components, the THD of the load current can be calculated. The THD of the load current is a core indicator for measuring the severity of harmonic pollution generated by the load, and it directly determines how much harmonic compensation current the energy storage converter needs to generate to purify the grid.

[0027] Specifically, S2 involves multi-dimensional demand calculation based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality metric set to obtain a demand set. This demand set includes the active power requirement, reactive power compensation requirement, apparent power requirement for harmonic compensation, and apparent power requirement for imbalance compensation. In other words, it transforms external dispatch commands and internal power quality assessment results into specific tasks that the energy storage converter (PCS) needs to perform in the four dimensions of active, reactive, harmonic, and imbalance. This demand set represents the compensation target under ideal conditions, providing a clear and quantifiable input for subsequent consideration of the energy storage converter's capacity constraints and dynamic allocation.

[0028] In its specific implementation, S2 firstly calculates the active power and fundamental frequency reactive power compensation requirements based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, the PCC voltage deviation rate, and the EMS active power command to obtain the active power task demand and the reactive power compensation demand. That is, the macro-level dispatch command issued by the upper-level energy management system (EMS), i.e., the EMS active power command, is transformed into a specific active power task, and simultaneously, based on the real-time grid voltage conditions, reactive power compensation requirements for voltage stabilization are generated.

[0029] In this process, firstly, the EMS active power command is deconstructed into an active power task to obtain the required active power. In practical applications of energy storage systems, the EMS formulates charging and discharging plans for energy storage units based on information such as electricity price signals and load forecasts, and executes these plans by issuing active power commands. The active power task deconstruction is a deterministic process; its core is to directly parse the EMS command into an active power reference value that the energy storage converter (PCS) must strictly adhere to. For example, when the EMS command is... This means that the energy storage system is required to deliver 400kW of active power to the grid. Therefore, the decomposed active power task demand is... That is, 400kW. This process ensures that the energy storage system can accurately respond to upper-level scheduling, realizing its economic value in applications such as energy time shifting and peak shaving. Secondly, based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, and the PCC voltage deviation rate, the active power and fundamental frequency reactive power compensation demand are calculated using the following formula to obtain the reactive power compensation demand: ; ; in, PCC voltage deviation rate, This represents the voltage deviation error for the current control cycle. This represents the voltage deviation error from the previous control cycle. and These are integral gain and proportional gain, respectively. This is to meet the reactive power compensation requirements of the previous control cycle. This refers to the reactive power compensation requirement for the current control cycle. Specifically, the reactive power compensation requirement for the current control cycle is set to the requirement value of the previous control cycle, with two adjustments added: the first adjustment is a proportional term, obtained by multiplying the difference between the current voltage deviation rate and the voltage deviation rate of the previous cycle by a proportional gain coefficient, reflecting the immediate response to the rate of change of voltage deviation; the second adjustment is an integral term, obtained by directly multiplying the current voltage deviation rate by an integral gain coefficient, used to accumulate and eliminate long-term static voltage deviations. The proportional term ensures the control system's rapid response to disturbances, preventing drastic fluctuations in voltage deviation; the integral term ensures that the system ultimately has no steady-state error, that is, it can accurately adjust the voltage to near the target value, thereby achieving precise and stable control of the PCC point voltage.

[0030] Next, step S2 calculates the apparent power requirement for harmonic compensation based on the three-phase instantaneous voltage at point PCC and the three-phase instantaneous current of the critical load to obtain the apparent power required for harmonic compensation. This step aims to determine the apparent power required to eliminate harmonic pollution generated by the critical load. Specifically, the control system uses the harmonic analysis results of the load current from the previous step to obtain the effective value of each harmonic current. Ideal harmonic compensation requires the energy storage converter to emit a compensation current equal in magnitude but opposite in phase to the load harmonic current. Therefore, the total apparent power required for harmonic compensation is the power consumed by injecting this compensation current at the current voltage at point PCC. Specifically, this process is expressed by the formula: ; in, Apparent power is required for harmonic compensation. This represents the effective value of the phase voltage at point PCC. The effective values ​​of the harmonic currents that need to be compensated are: The highest harmonic order that needs to be controlled. The harmonic orders requiring mitigation are numbered. That is, based on the previous harmonic analysis of the load current, the effective values ​​of all harmonic currents requiring mitigation are squared and then taken as the square root to obtain an equivalent total effective value of the total harmonic current. This total effective value of the harmonic current is then multiplied by the effective value of the phase voltage at the PCC point and the number of phases (3 for a three-phase system) to finally obtain the total apparent power required for harmonic compensation. To completely cancel the harmonics generated by the load, the energy storage converter must inject a harmonic current of equal magnitude but opposite phase. This calculation accurately quantifies the apparent power capacity of the energy storage converter required to inject this series of compensation currents under the current grid voltage, providing the most direct physical basis for assessing the power cost of harmonic mitigation tasks. Furthermore, step S2 calculates the apparent power demand for imbalance compensation based on the instantaneous three-phase voltage at the PCC point and the equivalent negative-sequence impedance upstream of the grid to obtain the apparent power required for imbalance compensation. This step aims to determine the apparent power required to correct the voltage imbalance at the PCC point. Through the symmetrical component decomposition in the previous step, the positive-sequence and negative-sequence components of the voltage at the PCC point are obtained. Here, it should be understood that the root cause of voltage imbalance lies in the existence of negative-sequence voltage. By injecting a precisely calculated negative-sequence current into the grid, a voltage drop equal in magnitude and opposite in direction to the original negative-sequence voltage can be generated on the upstream impedance, thereby achieving zeroing of the negative-sequence voltage at the PCC point. This method fundamentally solves the imbalance problem and accurately reflects the energy storage converter capacity required to eliminate the current voltage imbalance. In this process, firstly, based on the negative-sequence voltage component at the PCC point obtained by the symmetrical component method and the known equivalent negative-sequence impedance upstream of the power grid, the negative-sequence compensation current required to completely offset the negative-sequence voltage is calculated using Ohm's law. Then, the effective value of this calculated negative-sequence compensation current is multiplied by the effective value of the positive-sequence voltage component at the PCC point and the number of phases (3 for a three-phase system) to obtain the apparent power required for imbalance compensation. Specifically, this process is expressed by the formula: ; in, To compensate for the imbalance, the apparent power requirement, This represents the effective value of the positive sequence voltage component at point PCC. The negative sequence compensation current required to completely offset this negative sequence voltage This represents the effective value of the negative sequence voltage component at point PCC. The equivalent negative sequence impedance upstream of the grid is given; this calculation clarifies the power cost required to eliminate the current voltage imbalance.

[0031] Finally, S2 integrates the above calculation results and outputs a demand set. This demand set includes active power demand, reactive power compensation demand, apparent power demand for harmonic compensation, and apparent power demand for imbalance compensation. Active power demand refers to the active power required by the energy storage converter to complete economic or dispatchable tasks such as energy time-shifting. Reactive power compensation demand refers to the fundamental reactive power required to maintain voltage stability at the PCC point. Apparent power demand for harmonic compensation refers to the apparent power required to mitigate load harmonic pollution. Apparent power demand for imbalance compensation refers to the apparent power required to correct three-phase voltage imbalance at the PCC point. This demand set comprehensively defines the ideal operating target of the energy storage converter under current operating conditions.

[0032] Specifically, in step S3, dynamic weights are generated based on multi-attribute utility theory for the power quality metric set, battery state of charge, and active power demand to obtain a dynamic weight set. This dynamic weight set includes active power weight, reactive power weight, harmonic weight, and imbalance weight. In other words, to address the limitations of existing technologies employing fixed priority strategies—namely, the inability to dynamically adjust compensation priorities based on real-time changes in grid conditions—the present invention introduces multi-attribute utility theory from decision science to unify power quality indicators (such as voltage deviation percentage and harmonic distortion rate percentage) and system operating states (such as battery state of charge and active power command) of different natures and units into a dimensionless utility scale for scientific evaluation.

[0033] In specific implementation, step S3 first involves performing a utility transformation on the power quality metric set to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation. In an embodiment of the invention, the PCC voltage deviation rate, total harmonic distortion rate of the load current, and PCC voltage imbalance are respectively input into a general utility function to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation, respectively. The general utility function is expressed as follows: ; in, For general utility functions, This refers to the PCC voltage deviation rate, the total harmonic distortion rate of the load current, or the PCC voltage unbalance. for The corresponding normalized baseline value, for The corresponding risk aversion coefficient. In this process, firstly, the measured value of a specific power quality indicator, such as the PCC voltage deviation rate, the total harmonic distortion rate of the load current, or the measured value of the PCC voltage imbalance, is divided by its corresponding preset normalized benchmark value. This converts all indicators (voltage deviation, imbalance, harmonic distortion rate, etc.) in different physical units into a unified, dimensionless severity ratio. When this severity ratio is less than one, it indicates that the problem is within the standard range; when the severity ratio is greater than one, it indicates that the problem has exceeded the standard. The preset normalized benchmark value is usually a limit specified by national or industry standards. Next, this severity ratio is exponentially calculated, i.e., its... The power of power is used to simulate the tendency to avoid risk: when the problem is minor (severity ratio less than one), its utility value (i.e., basic weight) becomes smaller, and its priority is lower; while when the problem is severe (severity ratio greater than one), its utility value increases exponentially, thus obtaining a very high priority, ensuring that the system can concentrate resources to solve the most prominent and riskiest power quality problem. In the technical solution of this invention, by substituting the three indicators—PCC voltage deviation rate, total harmonic distortion rate of load current, and PCC voltage imbalance—into the logic of the above-mentioned general utility function for calculation, the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation, which quantify the severity and urgency of their respective problems, can be obtained.

[0034] Next, step S3 calculates the basic weight of the active task based on the battery's state of charge (SOC) and the power demand of the active task. Unlike power quality tasks, the priority of active tasks depends not only on the magnitude of their power demand but also on the state of the energy storage battery itself. Therefore, the calculation of its basic weight needs to comprehensively consider both factors. A typical implementation is that when the battery's SOC is in a healthy operating range, the basic weight of the active task is mainly determined by its power demand. The system determines the priority of active power tasks. When the battery's state of charge (SPC) approaches its upper or lower limits, its base weight should be significantly reduced or even reset to zero. This ensures that when the battery is in good condition, the system can actively respond to upper-level scheduling commands to obtain economic benefits; while when the battery's SPC approaches the danger boundaries of overcharging or over-discharging, the adjustment factor will be significantly reduced or even the base weight of active power tasks will be reset to zero, thereby forcibly reducing their priority and prioritizing the protection of expensive energy storage battery assets from damage.

[0035] Furthermore, step S3 aggregates and normalizes the basic weights for reactive power compensation, harmonic compensation, imbalance compensation, and active power tasks to obtain a dynamic weight set. In this process, firstly, all four basic weights calculated in the first two steps (active power task basic weight, reactive power compensation basic weight, harmonic compensation basic weight, and imbalance compensation basic weight) are added together to obtain a total basic weight value. Then, the basic weights for each task (active power task basic weight, reactive power compensation basic weight, harmonic compensation basic weight, and imbalance compensation basic weight) are divided by this total basic weight value to obtain the active power weight, reactive power weight, harmonic weight, and imbalance weight, respectively. These weights form the dynamic weight set. This method converts the absolute urgency score of each task into a relative importance percentage, ensuring that the sum of all final weights is exactly one. The resulting weight set can be directly and fairly used for the subsequent proportional allocation of the limited capacity of the energy storage converter, making the entire allocation process clear and based on evidence.

[0036] Specifically, in step S4, based on a dynamic weight set, the demand set is allocated according to the capacity constraints of the energy storage converter to obtain a set of instructions. This set of instructions includes the final active power instruction, the final fundamental reactive power instruction, the final harmonic compensation current instruction, and the final imbalance compensation current instruction. It should be understood that in actual operation, the energy storage converter may simultaneously face active power dispatching tasks from the upper-level energy management system (EMS), reactive power compensation requirements to maintain grid voltage stability, harmonic mitigation requirements to improve current waveforms, and imbalance compensation requirements to eliminate three-phase asymmetry. The sum of these multi-dimensional demands may exceed the rated apparent power capacity of the energy storage converter at certain times (e.g., under heavy load, grid disturbance, etc.). Without effective management and allocation, directly executing instructions exceeding the capacity range will lead to overload of the energy storage converter, thereby triggering protective shutdowns or even hardware damage, severely affecting the stability and reliability of the system. Therefore, in the technical solution of this invention, based on a dynamic weight set, the demand set is allocated with dynamic weight constraints to the energy storage converter capacity. When the total demand exceeds the energy storage converter capacity, the limited energy storage converter capacity can be rationally and dynamically allocated according to the real-time importance and urgency of each task. Specifically, by introducing dynamic weights generated based on real-time power quality assessment, the limited energy storage converter capacity is preferentially allocated to the most urgent power quality problems or the most important active power tasks, thereby maximizing the multi-functional value of the energy storage converter while ensuring equipment safety.

[0037] In its specific implementation, S4 first involves comprehensively aggregating the demand set and determining overload based on the rated apparent power of the energy storage converter to obtain the fundamental apparent power demand, total apparent power demand, and overload indicator. It should be understood that the total apparent power output of the energy storage converter (PCS), as a power electronic device, has an upper limit, determined by its hardware design and heat dissipation capacity—that is, the rated apparent power of the energy storage converter. However, the control system simultaneously generates multi-dimensional compensation demands, including active power, reactive power compensation, harmonic mitigation, and imbalance compensation, based on the grid status and upper-level dispatch. These demands are theoretically independent, and their simple superposition may easily exceed the capacity of the energy storage converter under certain extreme conditions (such as severe grid voltage drops coupled with severe load harmonic distortion). Therefore, before translating these idealized demands into actual instructions, comprehensive demand aggregation and overload determination are performed on the demand set and the rated apparent power of the energy storage converter to aggregate all discrete demands into a unified physical quantity directly comparable to the rated capacity of the energy storage converter—that is, the total apparent power demand. The overload flag directly determines the direction of the control strategy: if the energy storage converter has sufficient capacity, it can directly meet all the needs; if the energy storage converter has insufficient capacity, it is necessary to start the subsequent capacity allocation algorithm based on dynamic weights, at the cost of sacrificing the compensation effect of some secondary objectives, in order to ensure the overall stability of the system and the safety of the equipment.

[0038] In this process, the fundamental apparent power demand is first calculated. Both the active power demand and reactive power compensation demand fall under the fundamental frequency of the power grid. To unify these two orthogonal power components into a single apparent power value for subsequent aggregation with the apparent power of other non-fundamental tasks, their vector sum needs to be calculated. Specifically, the squares of the active power demand and reactive power compensation demand are calculated separately, then these two squares are added together, and finally the square root of the sum is taken to obtain the fundamental apparent power demand. The fundamental apparent power demand represents the fundamental frequency capacity of the energy storage converter required to meet the active and reactive power demands. Specifically, the fundamental apparent power demand is calculated using the following formula: ; in, For the fundamental apparent power requirement, Power required for active tasks This refers to the power required for reactive power compensation. It should be understood that active power and reactive power are physically orthogonal components, together constituting the fundamental apparent power. In a power vector diagram, they correspond to the two legs of a right triangle, while the fundamental apparent power is the hypotenuse. Therefore, using the Pythagorean theorem to synthesize these two components accurately reflects the total apparent power required by the energy storage converter to meet the fundamental frequency requirement.

[0039] Next, after calculating the fundamental apparent power demand, it needs to be aggregated with the demands of other non-fundamental components in the demand set to obtain the total apparent power demand. It should be understood that the total output current of the energy storage converter is a vector superposition of the fundamental current, harmonic currents, and negative-sequence current (used for imbalance compensation). According to Passavar's theorem, the square of the total power or total apparent power is equal to the sum of the squares of the power or apparent power of its various orthogonal components (such as fundamental, harmonic, and negative-sequence). Therefore, the apparent power demands of the fundamental, harmonic, and imbalance compensation components can be aggregated by taking the square root of the sum of squares. Specifically, the apparent power demands of the fundamental, harmonic, and imbalance compensation components are squared respectively to obtain their corresponding square values. These three square values ​​are then added together, and finally, the square root of the sum is calculated to obtain the total apparent power demand. The total apparent power demand comprehensively reflects the magnitude of the total apparent power that the energy storage converter needs to provide to perfectly achieve all compensation objectives.

[0040] Then, the total apparent power demand is directly compared with the known rated apparent power of the energy storage converter. If the total apparent power demand is greater than the rated apparent power of the energy storage converter, it means that the energy storage converter is about to face the risk of overload, and the overload flag is set to true; conversely, if the total apparent power demand is less than or equal to the rated apparent power of the energy storage converter, it means that the energy storage converter has sufficient capacity to meet all demands at the same time, and the overload flag is set to false.

[0041] Subsequently, in response to the overload flag being true, a weighted apparent power capacity allocation is performed on the demand set based on a dynamic weight set to obtain the apparent power allocated to the fundamental wave task, the apparent power allocated to harmonic compensation, and the apparent power allocated to imbalance compensation. It should be understood that when the overload flag is true, the energy storage converter is in an overload state. In this case, directly executing the original demand command would cause the energy storage converter current or internal DC bus voltage to exceed the safety threshold, triggering hardware protection and causing the energy storage converter to trip, thereby interrupting all its functions, including important active power support and critical power quality management. Simply reducing all tasks proportionally fails to reflect the priority differences of different tasks at specific times. For example, when the grid voltage deviates significantly from the normal range, reactive power compensation (belonging to the fundamental wave task) should have a much higher priority than harmonic compensation. Conversely, when the voltage is stable but the load harmonics are extremely high, the priority of harmonic compensation should be increased. Therefore, in the technical solution of this invention, a dynamic weight is introduced as a quantitative priority indicator to ensure that, under the predicament of limited resources, the energy storage converter can prioritize the use of its valuable capacity to solve the most prominent problems at present, thereby maximizing the system utility and achieving smooth operation.

[0042] In this process, firstly, the weights are integrated to obtain The dynamic weight set includes active power weights and reactive power weights. Both tasks fall under the fundamental frequency category and share the same fundamental frequency apparent power capacity. Therefore, these two weights need to be merged to form a unified fundamental frequency task weight, so that it can be compared and allocated at the same level as the harmonic weights and unbalanced weights. Specifically, this process is expressed by the following formula: ; in, For reactive weights, As a result of merit, Weights for fundamental wave tasks; Next, the total weight of the fundamental frequency task weight, harmonic weight, and unbalance weight is calculated; this process is expressed by the formula: ; in, For the total weight, For harmonic weights, The weights are unbalanced; then, the rated apparent power of the energy storage converter is allocated according to the proportion of each task's weight to the total weight. The apparent power allocated to the fundamental wave task The calculation formula is: ; Apparent power allocated to harmonic compensation The calculation formula is: ; Apparent power allocated to imbalance compensation The calculation formula is: ; The above calculations yielded the following results. , and In other words, under overload conditions, after priority arbitration, new and safe capacity limits are separately allocated for the fundamental frequency, harmonics, and imbalance compensation tasks. The rated apparent power of the energy storage converter.

[0043] Furthermore, the apparent power allocated to the fundamental wave task, the apparent power allocated to harmonic compensation, and the apparent power allocated to imbalance compensation are subjected to instruction deconstruction and safety verification to obtain an instruction set. Instruction deconstruction involves breaking down a unified apparent power capacity quota into specific instruction components that constitute that apparent power (e.g., decomposing the fundamental wave apparent power into active and reactive power instructions). Safety verification is a validation process designed to check whether the final generated instruction set satisfies the hardware constraints of the energy storage converter in all dimensions, particularly the total apparent power and phase current limits.

[0044] In this process, firstly, the apparent power allocated to the fundamental wave task is decomposed into the final active power command and the final fundamental wave reactive power command. The principle of decomposition is to maintain the original ratio between active and reactive power demand to reflect the original task's intent, only reducing it proportionally. First, the original fundamental wave apparent power demand needs to be calculated. Then, by comparing the allocated capacity with the original demand capacity, a uniform reduction factor is calculated; specifically, the reduction factor... The calculation formula is: ; After obtaining the reduction factor, multiply it by the original active power demand and reactive power demand respectively to obtain the final command value. Among them, the final active command The calculation formula is: ; Final fundamental reactive power command The calculation formula is: ; It is worth mentioning that if the system does not experience overload, the allocated capacity is equal to the demand capacity, the reduction factor is 1, and the final instruction is equal to the original demand.

[0045] Next, for harmonic and unbalanced compensation tasks, the compensation effect is ultimately achieved by injecting currents of specific frequencies and sequences. Therefore, the goal of instruction deconstruction is to generate the final harmonic compensation current command and the final unbalanced compensation current command. This process is similar to that of the fundamental frequency task, that is, proportionally reducing the originally calculated ideal compensation current command so that the apparent power generated by the final current command is exactly equal to the apparent power upper limit allocated to them. In practice, the reduction coefficients for each harmonic and unbalanced task can be calculated, and then these coefficients can be applied to the original ideal compensation current vector or its harmonic components to obtain the final compensation current command.

[0046] Furthermore, all the deconstructed final commands are aggregated and verified to confirm that the total apparent power generated by their combined action does not exceed the rated apparent power of the energy storage converter. Next, the final active, reactive, harmonic, and unbalanced compensation current commands are synthesized into a final three-phase instantaneous current reference signal. Then, this synthesized current signal is checked to ensure that its peak or RMS value in any phase does not exceed the maximum permissible single-phase output current specified by the energy storage converter hardware. If the check reveals an over-limit risk, the system can adopt further reduction strategies, such as fine-tuning or limiting all commands again, to ensure absolute safety. Only the set of commands that passes all safety checks is considered the final valid command.

[0047] Specifically, in step S5, the instruction set is processed to perform multi-functional compensation current synthesis and PWM signal generation to obtain the IGBT drive signal for the energy storage converter. It should be understood that the physical essence of the energy storage converter (PCS) is a high-frequency switching power converter composed of semiconductor switches (such as IGBTs), which cannot directly understand or execute high-level instructions in the instruction set. The direct control object of the energy storage converter is the on / off state of the IGBTs on its bridge arms. To achieve specific power output, in the technical solution of this invention, the specific output voltage and current waveforms are determined by precisely controlling the switching actions of these IGBTs at the microsecond level. Specifically, firstly, the instruction set containing multiple targets such as active power, reactive power, harmonics, and imbalance is translated into a single, comprehensive three-phase instantaneous current reference signal; then, through a high-performance control loop and modulation strategy, this ideal reference signal is converted into a pulse width modulation (PWM) signal capable of precisely controlling the IGBT switching state. Among them, PWM signal generation is a power electronic technology that generates a low-frequency sine wave (or other waveform) voltage or current with a specific amplitude and phase by changing the width of a series of high-frequency pulses. The resulting IGBT drive signal is a set (usually 6 channels) of precise, high-low level alternating digital logic signals. These signals are sent to the gate driver of the IGBT to directly control the turn-on and turn-off of the corresponding IGBT.

[0048] Specifically, firstly, the discrete command set is transformed into a continuous three-phase instantaneous current reference signal. This can be accomplished in a synchronously rotating coordinate system (dq coordinate system). First, the fundamental power command is transformed into a fundamental current command in the dq coordinate system. The final active power command corresponds to the d-axis current, and the final fundamental reactive power command corresponds to the q-axis current. The conversion logic depends on the dq components of the current grid voltage and the power calculation formula. Secondly, the final harmonic compensation current command and the final unbalance compensation current command are also transformed into the fundamental synchronously rotating dq coordinate system. Finally, all components, including the fundamental, harmonic, and unbalance compensation dq-axis current components, are vector-superimposed to obtain the total dq-axis reference current. This total reference current is then transformed back to the three-phase stationary coordinate system through an inverse coordinate transformation to obtain the final three-phase instantaneous current reference signal. Secondly, to ensure that the actual output current of the energy storage converter accurately tracks the reference current generated in the previous step, the actual three-phase output current of the energy storage converter is first measured by sensors and converted to the dq coordinate system to obtain the actual d-axis and q-axis current components. Then, the reference current is compared with the actual current to obtain the current error of the d-axis and q-axis. The PI controller calculates the required control voltage based on the error and adds a decoupling term to eliminate the coupling effect between the d-axis and q-axis, thus obtaining the dq-axis voltage reference value that the energy storage converter needs to generate. Next, the continuous voltage command obtained in the previous step is converted into discrete IGBT switching signals. During this process, the Space Vector Pulse Width Modulation (SVPWM) algorithm calculates the basic voltage vectors required within one PWM cycle and their respective durations based on the input voltage command. Based on these durations, the algorithm ultimately determines the on-time of the upper and lower switches of the three-phase bridge arms and generates six PWM waveforms. After processing such as dead-time insertion, these PWM waveforms form the final IGBT drive signals, which are sent to the IGBT gate drive circuit to control the precise switching of the IGBTs.

[0049] In summary, the energy storage converter compensation control method based on power quality assessment according to embodiments of the present invention is explained. First, it comprehensively and quantitatively assesses the power quality at the grid connection point, accurately identifying the severity of problems such as voltage deviation, harmonics, and imbalance. Next, based on multi-attribute utility theory, it transforms various power quality indicators and active power requirements into dynamic weights, thereby scientifically quantifying the real-time urgency of different compensation tasks. Finally, it optimally allocates the limited capacity of the energy storage converter according to this dynamic weight system. This method enables a shift in compensation strategy from a fixed priority mode to a dynamic adaptive mode, ensuring that when the capacity of the energy storage converter is limited, the most urgent power quality issues are addressed first, thereby significantly improving the comprehensive compensation effect and grid support capability of the energy storage system under complex operating conditions.

[0050] This invention also provides a power storage converter compensation control system based on power quality assessment.

[0051] Figure 3 This is a block diagram of an energy storage converter compensation control system based on power quality assessment according to an embodiment of the present invention. Figure 3 As shown, the energy storage converter compensation control system 300 based on power quality assessment according to an embodiment of the present invention includes: a power quality index decomposition module 310, used to decompose the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the critical load into power quality indexes to obtain a power quality metric set, the power quality metric set including the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage imbalance; and a multi-dimensional demand calculation module 320, used to perform multi-dimensional demand calculation based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality metric set to obtain a demand set, the demand set including the active power demand, the reactive power compensation demand, the apparent power demand for harmonic compensation, and the apparent power demand for imbalance compensation. The dynamic weight generation module 330 is used to generate a dynamic weight set based on the multi-attribute utility theory of the power quality measurement set, battery state of charge, and active power demand. The dynamic weight set includes active power weight, reactive power weight, harmonic weight, and imbalance weight. The PCS capacity constraint allocation module 340 is used to allocate the energy storage converter capacity constraint based on the dynamic weight set to the demand set to obtain a command set. The command set includes the final active power command, the final fundamental reactive power command, the final harmonic compensation current command, and the final imbalance compensation current command. The PWM signal generation module 350 is used to synthesize multi-functional compensation current and generate PWM signals from the command set to obtain the IGBT drive signal of the energy storage converter.

[0052] The specific implementation method of the energy storage converter compensation control system based on power quality assessment provided in this embodiment of the invention can be found in the description of the energy storage converter compensation control method based on power quality assessment provided in this embodiment of the invention, and will not be repeated here.

[0053] The energy storage converter compensation control system 300 based on power quality assessment according to embodiments of the present invention can be implemented in various wireless terminals, such as servers with energy storage converter compensation control algorithms based on power quality assessment. In one possible implementation, the energy storage converter compensation control system 300 based on power quality assessment according to embodiments of the present invention can be integrated into the wireless terminal as a software module and / or a hardware module. For example, the energy storage converter compensation control system 300 based on power quality assessment can be a software module in the operating system of the wireless terminal, or it can be an application developed for the wireless terminal; of course, the energy storage converter compensation control system 300 based on power quality assessment can also be one of many hardware modules of the wireless terminal.

[0054] Alternatively, in another example, the energy storage converter compensation control system 300 based on power quality assessment and the wireless terminal can also be separate devices, and the energy storage converter compensation control system 300 based on power quality assessment can be connected to the wireless terminal via wired and / or wireless networks, and transmit interactive information in accordance with an agreed data format.

[0055] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A compensation control method for an energy storage converter based on power quality assessment, characterized in that, The energy storage converter compensation control method based on power quality assessment includes: Power quality indicators are decomposed into power quality metrics for the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the critical load to obtain a set of power quality metrics. The set of power quality metrics includes the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage unbalance. Multidimensional demand calculations are performed based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality measurement set to obtain the demand set, which includes the active power demand, reactive power compensation demand, apparent power demand for harmonic compensation, and apparent power demand for imbalance compensation. Dynamic weights are generated based on multi-attribute utility theory for the power quality measurement set, battery state of charge, and active power demand to obtain a dynamic weight set, which includes active weight, reactive weight, harmonic weight, and imbalance weight. Based on the dynamic weight set, the demand set is allocated according to the capacity constraints of the energy storage converter to obtain the instruction set. The instruction set includes the final active power instruction, the final fundamental reactive power instruction, the final harmonic compensation current instruction, and the final imbalance compensation current instruction. The instruction set is used to perform multi-functional compensation current synthesis and PWM signal generation to obtain the IGBT drive signal for the energy storage converter.

2. The energy storage converter compensation control method based on power quality assessment according to claim 1, characterized in that, Power quality metrics are decomposed from the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the critical load to obtain a set of power quality measures, including: The instantaneous three-phase voltage at the PCC point is decomposed into grid voltage synchronization and symmetrical components to obtain the PCC voltage deviation rate, PCC voltage unbalance, and grid fundamental positive sequence voltage synchronization phase-locking angle. The load current harmonic decomposition and distortion rate calculation are performed on the synchronous phase-locked angle of the three-phase instantaneous current of the critical load and the fundamental positive sequence voltage of the power grid to obtain the total harmonic distortion rate of the load current.

3. The energy storage converter compensation control method based on power quality assessment according to claim 1, characterized in that, A multi-dimensional demand calculation is performed based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality metrics set to obtain the demand set, including: Based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, the PCC voltage deviation rate, and the EMS active power command, the active power and fundamental frequency reactive power compensation demand is calculated to obtain the active power task demand and reactive power compensation demand. The apparent power demand for harmonic compensation is calculated based on the three-phase instantaneous voltage at point PCC and the three-phase instantaneous current of the critical load. The apparent power demand for unbalanced compensation is calculated based on the three-phase instantaneous voltage at the PCC point and the equivalent negative sequence impedance upstream of the grid.

4. The energy storage converter compensation control method based on power quality assessment according to claim 3, characterized in that, Based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, the PCC voltage deviation rate, and the EMS active power command, the active power and fundamental frequency reactive power compensation demands are calculated to obtain the active power task demand and reactive power compensation demand, including: The active power command of EMS is deconstructed into an active power task to obtain the active power demand of the task. Based on the reactive power compensation demand of the previous control cycle, the voltage deviation error of the previous control cycle, and the PCC voltage deviation rate, the active power and fundamental frequency reactive power compensation demand are calculated using the following formula to obtain the reactive power compensation demand: ； ； in, PCC voltage deviation rate, This represents the voltage deviation error for the current control cycle. This represents the voltage deviation error from the previous control cycle. and These are integral gain and proportional gain, respectively. This is to meet the reactive power compensation requirements of the previous control cycle. This is for the reactive power compensation requirement of the current control cycle.

5. The energy storage converter compensation control method based on power quality assessment according to claim 1, characterized in that, Dynamic weight set is obtained by generating dynamic weights based on multi-attribute utility theory for the power quality metric set, battery state of charge, and active power demand, including: The power quality measurement set is transformed into utility to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation. The basic weight of the active task is calculated based on the battery state of charge and the power required by the active task. The basic weights of reactive power compensation, harmonic compensation, imbalance compensation, and active power task are aggregated and normalized to obtain a dynamic weight set.

6. The energy storage converter compensation control method based on power quality assessment according to claim 5, characterized in that, The power quality metrics set is transformed into utility values ​​to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation, including: Input the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage imbalance into the general utility function to obtain the basic weights for reactive power compensation, harmonic compensation, and imbalance compensation, respectively.

7. The energy storage converter compensation control method based on power quality assessment according to claim 6, characterized in that, The general utility function is expressed as: ； in, For general utility functions, This refers to the PCC voltage deviation rate, the total harmonic distortion rate of the load current, or the PCC voltage unbalance. for The corresponding normalized baseline value, for The corresponding risk aversion coefficient.

8. The energy storage converter compensation control method based on power quality assessment according to claim 5, characterized in that, The basic weights for reactive power compensation, harmonic compensation, imbalance compensation, and active power tasks are aggregated and normalized to obtain a dynamic weight set, including: The total basic weight value is obtained by adding the basic weights of reactive power compensation, harmonic compensation, imbalance compensation, and active power task. Divide the reactive power compensation base weight, harmonic compensation base weight, unbalanced compensation base weight, and active power task base weight by the total base weight value to obtain the corresponding active power weight, reactive power weight, harmonic weight, and unbalanced weight, respectively.

9. The energy storage converter compensation control method based on power quality assessment according to claim 1, characterized in that, Based on a dynamic weight set, the demand set is allocated according to the capacity constraints of energy storage converters to obtain the instruction set, including: A comprehensive demand aggregation and overload determination are performed on the demand set and the rated apparent power of the energy storage converter to obtain the fundamental apparent power demand, the total apparent power demand and the overload indicator. In response to the overload flag being true, the apparent power capacity of the demand set is allocated based on the dynamic weight set to obtain the apparent power allocated to the fundamental task, the apparent power allocated to harmonic compensation, and the apparent power allocated to unbalance compensation. The apparent power allocated to the fundamental wave task, the apparent power allocated to harmonic compensation, and the apparent power allocated to unbalance compensation are deconstructed and security-checked to obtain the instruction set.

10. A power storage converter compensation control system based on power quality assessment, characterized in that, The energy storage converter compensation control system based on power quality assessment includes: The power quality index decomposition module is used to decompose the power quality index of the three-phase instantaneous voltage at the PCC point and the three-phase instantaneous current of the key load to obtain a set of power quality metrics. The set of power quality metrics includes the PCC voltage deviation rate, the total harmonic distortion rate of the load current, and the PCC voltage unbalance. The multi-dimensional demand calculation module is used to perform multi-dimensional demand calculations based on the three-phase instantaneous voltage at the PCC point, the three-phase instantaneous current of the critical load, the EMS active power command, and the power quality measurement set to obtain the demand set. The demand set includes the active task demand power, reactive power compensation demand power, harmonic compensation demand apparent power, and unbalance compensation demand apparent power. The dynamic weight generation module is used to generate dynamic weights based on the multi-attribute utility theory for the power quality measurement set, battery state of charge and active power demand to obtain a dynamic weight set. The dynamic weight set includes active weight, reactive weight, harmonic weight and unbalance weight. The PCS capacity constraint allocation module is used to allocate the demand set based on dynamic weights to the energy storage converter capacity constraint to obtain the instruction set. The instruction set includes the final active power instruction, the final fundamental reactive power instruction, the final harmonic compensation current instruction, and the final imbalance compensation current instruction. The PWM signal generation module is used to perform multi-functional compensation current synthesis and PWM signal generation on the instruction set to obtain the IGBT drive signal of the energy storage converter.

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