Method and device for controlling active power of optical storage magnetic anti-type dynamic voltage restorer

Abstract

The application provides a control method and device for active power of a light energy storage magnetic anti-form dynamic voltage restorer, relates to the technical field of power electronics, and is based on a current time limit sliding time window, collects voltage instantaneous values of a power grid side and a load side, determines a power grid side fundamental wave voltage amplitude, a load actual fundamental wave voltage amplitude and a target frequency voltage harmonic equivalent amplitude, extracts available active power of energy storage, presets a fundamental wave and harmonic compensation coefficient, calculates a fundamental wave voltage deviation rate and a harmonic deviation rate, respectively calculates a fundamental wave and harmonic active power compensation amount when the fundamental wave voltage deviation rate reaches a preset deviation threshold, and superimposes to obtain total compensation active power demand; according to a comparison result of available active power of energy storage and total compensation demand, the distribution proportion of the two is adjusted, based on a monitoring interval containing multiple sliding windows, a fundamental wave voltage amplitude change slope and a fundamental wave voltage deviation rate variance are calculated, and the fundamental wave compensation coefficient is adjusted to correct the total compensation demand.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to a method and apparatus for controlling the active power of a photoelectric storage magnetic reactance dynamic voltage restorer. Background Technology

[0002] As a core device for solving power quality problems and improving the utilization rate of clean energy, the dynamic voltage restorer combining photovoltaic and energy storage has received widespread attention and research. Its energy storage unit needs to respond quickly when transient disturbances occur, output or absorb active power, and maintain the stability of the load voltage.

[0003] In the prior art, CN119315646A discloses a method for controlling the active power of a photovoltaic-storage dynamic voltage restorer. This method addresses normal grid operation, voltage dips, and voltage spikes by using vector control to adjust the phase relationship between the grid and the load, enabling the energy storage unit to output active power according to a preset logic. When a voltage dip occurs, the energy storage unit quickly releases active power to compensate for the voltage drop and maintain a constant load voltage. When a voltage spike occurs, the energy storage unit absorbs excess active power to prevent load damage due to overvoltage. However, this method is difficult to adapt to nonlinear loads. Nonlinear loads mainly generate characteristic harmonics such as the 3rd, 5th, and 7th harmonics, which persist and cause additional active power losses. This results in a phase deviation between the active power output of the energy storage unit and the actual load demand during transient disturbances, reducing compensation accuracy and making it impossible to quickly offset the impact of grid transient disturbances. It may even exacerbate voltage fluctuations at the load end. The voltage of a nonlinear load includes the fundamental frequency and the 3rd, 5th, and 7th harmonics. The distortion of secondary characteristic harmonics is essentially the result of the superposition of harmonics and fundamental frequency, rather than the instantaneous fluctuation of the fundamental frequency itself. The harmonic separation process relies on long-term calculations over a complete cycle, making it difficult to complete separation and compensation decisions within the millisecond-level transient disturbance window such as voltage dips and surges. Furthermore, due to the computational delay and signal acquisition delay of the hardware itself, the compensation action always lags behind the dynamic changes in fundamental frequency deviation and harmonic loss.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for controlling the active power of a photoelectric storage magnetic reactance dynamic voltage restorer, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The active power control method of the photovoltaic storage magnetic reactance type dynamic voltage restorer includes the following specific steps: The current sliding time window is defined based on the current moment, and the amplitude of the grid-side fundamental voltage, the amplitude of the actual load fundamental voltage, and the equivalent amplitude of the target frequency voltage harmonics on the load side are determined based on the instantaneous values ​​of the grid-side voltage and the load-side voltage within the current sliding time window. The available active power of energy storage at the current moment is also extracted. The fundamental voltage compensation coefficient and harmonic compensation coefficient are preset. The fundamental voltage deviation rate is calculated based on the fundamental voltage amplitude of the grid side and the actual fundamental voltage amplitude of the load. The harmonic deviation rate is calculated by comparing the equivalent amplitude of the target frequency voltage harmonic with the actual fundamental voltage amplitude of the load. When the fundamental voltage deviation rate is not less than the preset deviation threshold, the fundamental active power compensation amount is calculated based on the fundamental voltage deviation rate, the fundamental compensation coefficient, and the actual fundamental voltage amplitude of the load. The harmonic active power compensation amount is calculated based on the harmonic compensation coefficient and the equivalent amplitude of the harmonic harmonic of the target frequency voltage. The sum of the fundamental active power compensation amount and the harmonic active power compensation amount is taken as the total compensation active power requirement. Based on the comparison between the available active power of energy storage and the total compensation active power demand, the allocation ratio of fundamental active power compensation and harmonic active power compensation is adjusted. Calculate the slope of the change in the fundamental voltage amplitude on the grid side and the variance of the fundamental voltage deviation rate within the monitoring time interval, and adjust the fundamental compensation coefficient accordingly. Then, use the adjusted fundamental compensation coefficient to correct the total compensation active power demand.

[0007] Furthermore, the sliding time window ends at the current time and has a duration of not less than 5ms, with a sliding step size of 2ms. The monitoring time interval is N-1 consecutive historical sliding time windows that terminate at the current sliding time window. All sliding windows are arranged in a continuous overlapping manner according to a preset sliding step size, where N is an integer from 2 to 4.

[0008] Furthermore, the method for determining the fundamental voltage amplitude on the grid side, the actual fundamental voltage amplitude at the load, and the equivalent amplitude of the target frequency voltage harmonics on the load side is as follows: Within each sliding time window, the instantaneous values ​​of the grid-side voltage and the load-side voltage collected are respectively constructed into sequences; Extracting the fundamental voltage amplitude on the grid side: The fundamental phase is determined by the synchronous rotating coordinate system phase-locked method for the sequence of instantaneous voltage values ​​on the grid side. Several fundamental voltage components are separated from the sequence based on the fundamental phase, and the root mean square value of the fundamental voltage components is taken as the fundamental voltage amplitude on the grid side. Extracting the actual fundamental voltage amplitude of the load: Determine the fundamental phase based on the sinusoidal waveform of the rated fundamental voltage of the load, select the time period that is consistent with the fundamental phase from the current sliding time window, and calculate the root mean square value of the instantaneous value of the rated fundamental voltage of the load in the time period as the actual fundamental voltage amplitude of the load. The equivalent amplitude of the target frequency voltage harmonics is extracted: the short-time Fourier transform method is used to decompose the full frequency spectrum of the instantaneous voltage value sequence on the load side to obtain the harmonic spectrum distribution. The amplitudes of the 3rd, 5th and 7th harmonics are extracted under the harmonic spectrum distribution, and the ratio of the amplitude of each frequency to the amplitude of the actual fundamental voltage of the load is calculated. The frequencies with a ratio greater than 1% are taken as the target frequencies to extract several target frequency voltage harmonic components and obtain the target frequency current harmonic components. The power factors of voltage harmonics and current harmonics at each target frequency are collected. The product of the voltage harmonic component at the target frequency, the current harmonic component at the same frequency, and the power factor is taken as the active power of the voltage harmonics at each target frequency. The proportion of the active power of the voltage harmonics at each target frequency to the sum of the active power of the voltage harmonics at all target frequencies is taken as a weighting coefficient. The amplitudes of the harmonics at each target frequency are weighted and summed to obtain the equivalent amplitude of the voltage harmonics at the target frequency.

[0009] Furthermore, the fundamental voltage deviation rate is calculated based on the fundamental voltage amplitude on the grid side and the actual fundamental voltage amplitude of the load. The harmonic deviation rate is calculated by comparing the equivalent amplitude of the target frequency voltage harmonics with the actual fundamental voltage amplitude of the load. Using the actual fundamental voltage amplitude of the load as a reference, the relative error between the fundamental voltage amplitude on the grid side and the reference is calculated as the fundamental voltage deviation rate. Using the actual fundamental voltage amplitude of the load as a reference, the ratio of the equivalent amplitude of the target frequency voltage harmonics to the reference is calculated as the harmonic deviation rate.

[0010] Furthermore, the deviation threshold is 10%.

[0011] Furthermore, the method for calculating the fundamental active power compensation based on the fundamental voltage deviation rate, the fundamental compensation coefficient, and the actual fundamental voltage amplitude of the load, and the method for calculating the harmonic active power compensation based on the harmonic compensation coefficient and the equivalent amplitude of the target frequency voltage harmonics, is as follows: First, the fundamental equivalent impedance on the load side is calculated: Extract the amplitude of the fundamental current on the grid side: The fundamental phase is determined based on the sinusoidal waveform of the load's rated fundamental voltage. The time period that matches the fundamental phase is selected from the current sliding time window, and the root mean square value of the instantaneous value of the load's rated fundamental current during that time period is calculated as the actual fundamental current amplitude of the load. The ratio of the fundamental voltage amplitude on the grid side to the fundamental current amplitude on the grid side is used as the fundamental equivalent impedance on the load side. Calculate the fundamental active power compensation: The ratio of the square of the product of the fundamental voltage deviation rate, the fundamental compensation coefficient, and the actual fundamental voltage amplitude of the load to the fundamental equivalent impedance on the load side is used as the fundamental active power compensation amount. The equivalent harmonic impedance at each target frequency on the load side is calculated: For the current harmonic components of each target frequency on the load side, their root mean square values ​​are extracted as the current harmonic amplitude of the corresponding frequency, and the ratio of the voltage harmonic amplitude to the current harmonic amplitude of the same frequency on the load side is used as the harmonic equivalent impedance at that target frequency. Calculate the harmonic active power compensation amount: The product of the harmonic compensation coefficient and the square of the equivalent amplitude of the harmonics at the corresponding target frequency is used as the ratio of the equivalent impedance of the harmonics on the load side at that target frequency. This ratio is then used as the harmonic active power compensation amount for a single target frequency. The sum of the harmonic active power compensation amounts for each target frequency is then used as the harmonic active power compensation amount.

[0012] Furthermore, the method for adjusting the allocation ratio of fundamental active power compensation and harmonic active power compensation based on the comparison between the available active power of energy storage and the total compensation active power demand is as follows: If the available active power of energy storage is not less than the total compensation active power requirement, the allocation ratio of the fundamental active power compensation amount to the harmonic active power compensation amount is the ratio of the two, that is, there is no need to adjust the values ​​of the two. If the available active power of energy storage is less than the total compensation active power demand, but not less than the fundamental active power compensation amount, first calculate the ratio of the fundamental active power compensation amount to the harmonic active power compensation amount, and then allocate the available active power of energy storage according to this ratio. The active power allocated to the fundamental is the available active power of energy storage multiplied by the proportion of the fundamental active power compensation amount to the sum of the fundamental active power compensation amount and the harmonic active power compensation amount. The active power allocated to the harmonic is the available active power of energy storage multiplied by the proportion of the harmonic demand to the total demand. If the available active power of energy storage is less than the fundamental active power compensation amount, the allocation ratio of the fundamental active power compensation amount to the harmonic active power compensation amount is set to 1:0, that is, the available active power of energy storage is fully allocated to the fundamental active power compensation amount.

[0013] Furthermore, the method for calculating the slope of the change in the fundamental voltage amplitude on the grid side and the variance of the fundamental voltage deviation rate within the monitoring time interval is as follows: Obtain the fundamental voltage amplitude and fundamental voltage deviation rate of the grid side corresponding to all sliding windows within the monitoring time interval; For a single sliding time window, based on the sinusoidal waveform of the load's rated fundamental voltage, the period within the sliding time window where the fundamental phase is consistent is located. The instantaneous value of the load's rated fundamental voltage during this period is extracted and linearly fitted. The slope is used as the normal reference slope. The fundamental voltage component is linearly fitted to obtain the actual slope. The difference between the actual slope and the normal reference slope is used as the trend deviation of the sliding time window. The average trend deviation of all sliding time windows is used as the slope of the change in the fundamental voltage amplitude on the grid side. Obtain the fundamental voltage deviation rate corresponding to all sliding windows within the monitoring time interval, and use the calculated variance as the variance of the fundamental voltage deviation rate within the monitoring time interval.

[0014] Furthermore, the method for adjusting the fundamental frequency compensation coefficient is as follows: Preset the lower and upper threshold values ​​for slope, and the variance baseline value; When the slope of the fundamental voltage amplitude change is less than the lower threshold of the slope, the fundamental voltage compensation coefficient is increased by 5%. When the slope of the fundamental voltage amplitude change is greater than the upper threshold of the slope, the fundamental voltage compensation coefficient is decreased by 5%. If the slope is between the lower threshold of the slope and the upper threshold of the slope, the variance of the fundamental voltage deviation rate is further analyzed. When the variance of the fundamental voltage deviation rate is greater than the variance benchmark value, the fundamental voltage compensation coefficient is increased by 5%. The lower threshold of the slope is negative, the upper threshold of the slope is positive, and the variance benchmark value is positive.

[0015] Additionally, a control device for the active power of a photoelectric storage magnetic reactance dynamic voltage restorer is provided. This device is used to execute the aforementioned control method for the active power of the photoelectric storage magnetic reactance dynamic voltage restorer, including: The data extraction module is used to define the current sliding time window based on the current moment, and to determine the fundamental voltage amplitude of the grid side, the actual fundamental voltage amplitude of the load, and the equivalent amplitude of the target frequency voltage harmonic of the load side based on the instantaneous voltage values ​​of the grid side and the load side within the current sliding time window, and to extract the available active power of energy storage at the current moment. The deviation calculation module is used to pre-set the fundamental compensation coefficient and harmonic compensation coefficient, calculate the fundamental voltage deviation rate based on the fundamental voltage amplitude of the grid side and the actual fundamental voltage amplitude of the load, and calculate the harmonic deviation rate by comparing the equivalent amplitude of the target frequency voltage harmonic with the actual fundamental voltage amplitude of the load. The demand extraction module is used to calculate the fundamental active power compensation amount based on the fundamental voltage deviation rate, fundamental compensation coefficient, and actual fundamental voltage amplitude of the load when the fundamental voltage deviation rate is not less than the preset deviation threshold. It also calculates the harmonic active power compensation amount based on the harmonic compensation coefficient and the equivalent amplitude of the harmonic harmonic of the target frequency voltage. The sum of the fundamental active power compensation amount and the harmonic active power compensation amount is taken as the total compensation active power demand. The power distribution module is used to compare the available active power of energy storage with the total compensation active power demand, and adjust the distribution ratio of the fundamental active power compensation amount and the harmonic active power compensation amount. The power regulation module is used to calculate the slope of the change in the amplitude of the fundamental voltage on the grid side and the variance of the fundamental voltage deviation rate within the monitoring time interval, and adjust the fundamental compensation coefficient accordingly. The adjusted fundamental compensation coefficient is then used to correct the total compensation active power demand.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention completes the separation and equivalent amplitude calculation of target frequency voltage harmonics on the load side within a sliding time window, and uses DVR to specifically counteract the influence of target frequency harmonics generated by nonlinear loads, thereby rapidly improving power quality stability. This invention also calculates the variance of the slope of the fundamental voltage amplitude change and the fundamental voltage deviation rate within multiple sliding time windows, which has a certain effect on predicting the dynamic change trend and fluctuation stability of the fundamental voltage. In this way, the fundamental compensation coefficient is dynamically adjusted to correct the total compensation active power demand, thereby achieving forward-looking regulation. At the same time, by combining the real-time comparison between the available active power of energy storage and the total compensation demand, the fundamental compensation amount allocation ratio is adjusted, effectively avoiding the accuracy loss caused by traditional lag compensation, and ensuring that the energy storage compensation response under transient disturbances is accurately matched with the fundamental and harmonic active power demand of the nonlinear load. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall method flow of the present invention; Figure 2 This is a schematic diagram of the overall device structure of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0019] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] Example: Please see Figure 1 The present invention provides a technical solution: The active power control method of the photovoltaic storage magnetic reactance type dynamic voltage restorer includes the following specific steps: S1: Determine the current sliding time window based on the current moment, and determine the fundamental voltage amplitude of the grid side, the actual fundamental voltage amplitude of the load, and the equivalent amplitude of the target frequency voltage harmonic of the load side based on the instantaneous voltage values ​​of the grid side and the load side within the current sliding time window, and extract the available active power of energy storage at the current moment. The current sliding time window is defined based on the current moment. The duration of the sliding time window is not less than 5ms, and the sliding step size is 2ms. In each sliding time window, the instantaneous voltage values ​​of the grid side and the load side are collected in real time on the grid side and the load side, and sequences are constructed respectively. The duration is set because the power frequency of the grid is 50Hz, that is, one cycle is 20ms, and 5ms corresponds to 1 / 4 of the cycle. Sufficient voltage instantaneous value samples can be collected to avoid distortion in the extraction of fundamental amplitude and harmonic frequency due to insufficient samples. At the same time, the determination of voltage sag needs to be based on the voltage change trend in a short period of time, so as to ensure rapid compensation in the future. The sliding step size of 2ms can ensure the continuity of the voltage instantaneous value sequence. The overlapping part of adjacent windows can characterize the continuous characteristics of voltage change. When multiple sliding time windows are judged in a comprehensive manner in the future, the active power adjustment will not be delayed due to excessive time. Extracting the fundamental voltage amplitude on the grid side: For the sequence of instantaneous voltage values ​​on the grid side, the fundamental phase is determined using a synchronous rotating coordinate system phase-locked loop (PLL) method. Specifically, the sequence of instantaneous voltage values ​​is transformed into a synchronously rotating dq coordinate system. The phase change of the fundamental voltage is tracked in real time by a proportional-integral regulator to eliminate the influence of voltage harmonics and phase fluctuations on the accuracy of the PLL. Finally, a stable grid-side fundamental voltage phase signal is output. Voltage components with the same frequency and phase as the fundamental phase are retained, and all harmonic components with frequencies different from the fundamental are filtered out. This yields a subsequence of instantaneous grid-side fundamental voltage values ​​containing only the fundamental component, i.e., the fundamental voltage component. The root mean square value calculated for the fundamental voltage component is taken as the grid-side fundamental voltage amplitude. Extracting the actual fundamental voltage amplitude of the load: Determine the fundamental phase based on the sinusoidal waveform of the load's rated fundamental voltage, select the time period that matches the fundamental phase from the current sliding time window, and calculate the root mean square value of the instantaneous value of the load's rated fundamental voltage during the time period as the root mean square value of the actual fundamental voltage amplitude of the load. The equivalent amplitude of the target frequency voltage harmonics is extracted as follows: The short-time Fourier transform is used to decompose the full-frequency spectrum of the instantaneous load-side voltage value sequence. A Hanning window is selected as the transform window function to avoid spectral spread of the signal and maintain the independence of each harmonic spectral peak. The window length is consistent with the sliding time window duration. This transform converts the time-domain instantaneous voltage value sequence into a frequency-domain harmonic spectrum distribution, which contains amplitude and phase information of each harmonic. The amplitude data corresponding to the 3rd, 5th, and 7th harmonics are extracted from the harmonic spectrum distribution. The ratio of each harmonic amplitude to the actual fundamental voltage amplitude of the load is calculated. If the ratio is less than 1%, it is discarded. Harmonic components that meet the conditions are separated to obtain the target frequency voltage harmonic components. The same method is used to decompose the full-frequency spectrum of the instantaneous load-side current value to obtain the target frequency current harmonic components. The 3rd, 5th, and 7th harmonics are the main sources of pollution for nonlinear loads. Among them, higher-order harmonics have less harm to the load and the power grid and basically do not affect power quality. For each target frequency, the phase signals of the voltage harmonic and current harmonic at that frequency are obtained by using the phase spectrum of the short-time Fourier transform. The phase difference between the two is calculated, and the cosine value of the phase difference is taken, which is the power factor of the voltage harmonic and current harmonic at that target frequency. The product of the voltage harmonic component of the target frequency, the current harmonic component of the same frequency, and the power factor is taken as the active power of the voltage harmonic at each target frequency. The proportion of the active power of the voltage harmonic at each target frequency to the sum of the active power of the voltage harmonic at all target frequencies is taken as a weighting coefficient. The harmonic amplitude is weighted and summed to obtain the equivalent amplitude of the voltage harmonic at the target frequency. This value comprehensively represents the degree of joint impact of each high-contribution harmonic on the power quality of the power grid. In this way, the compensation priority can be allocated according to the actual degree of harmonic damage, i.e., active power contribution, to avoid each harmonic occupying active power equally. Available active power of energy storage refers to the maximum active power that the energy storage system can output at the current moment. As the energy storage capacity decreases, the available active power also decreases. Therefore, the available active power of energy storage at the current moment is extracted, and then the processing logic for the fundamental frequency and harmonics is determined in the subsequent judgment.

[0021] S2: Pre-set the fundamental voltage compensation coefficient and harmonic compensation coefficient, calculate the fundamental voltage deviation rate based on the fundamental voltage amplitude of the grid side and the actual fundamental voltage amplitude of the load, and calculate the harmonic deviation rate by comparing the equivalent amplitude of the target frequency voltage harmonic with the actual fundamental voltage amplitude of the load. The core function of pre-setting the fundamental voltage compensation coefficient and harmonic voltage compensation coefficient is to quantify the compensation intensity of the DVR for the fundamental voltage deviation and harmonic voltage deviation, providing an adjustment basis for the subsequent calculation of active power compensation. The core objective of the fundamental voltage compensation coefficient is to quickly restore the fundamental voltage to the rated load level. It is affected by load characteristics, grid conditions, power quality standards, etc., so the value of this coefficient is between 0.8 and 1. The objective of the harmonic compensation coefficient is to suppress high-harmonics, but harmonic compensation has a lower priority than fundamental voltage compensation and must be based on not occupying too much active power of energy storage. Therefore, the value of this coefficient is between 0.3 and 0.7, and is dynamically adjusted according to the severity of harmonics. By independently setting the compensation coefficient, the compensation intensity of the fundamental wave and harmonics can be adjusted separately. While prioritizing the stability of the fundamental wave, harmonics can be suppressed as needed. This is because the fundamental wave voltage deviation directly determines whether the load can operate normally and is a core indicator of power quality. The harmonic deviation mainly affects the load operating efficiency. By independently setting the compensation coefficient, the compensation intensity of the fundamental wave and harmonics can be adjusted separately. The harmonic compensation coefficient is used to define the proportional reference for harmonic suppression in the active power output of the DVR, prioritizing the stability of the fundamental wave while suppressing harmonics as needed. Using the actual fundamental voltage amplitude of the load as a reference, the relative error between the fundamental voltage amplitude of the grid side and the reference is calculated as the fundamental voltage deviation rate. When the fundamental voltage amplitude of the grid side is lower than the reference, the fundamental voltage deviation rate is directly determined to be 0 to avoid treating overvoltage as a voltage sag. Using the actual fundamental voltage amplitude of the load as a reference, the ratio of the equivalent amplitude of the target frequency voltage harmonic to the reference is calculated as the harmonic deviation rate.

[0022] S3: When the fundamental voltage deviation rate is not less than the preset deviation threshold, the fundamental active power compensation amount is calculated based on the fundamental voltage deviation rate, the fundamental compensation coefficient, and the actual fundamental voltage amplitude of the load. The harmonic active power compensation amount is calculated based on the harmonic compensation coefficient and the equivalent amplitude of the harmonics of the target frequency voltage. The sum of the fundamental active power compensation amount and the harmonic active power compensation amount is taken as the total compensation active power requirement. For the voltage of the power grid in ordinary industrial areas, there will be frequent small dips of 3%-8%. Therefore, the preset deviation threshold is 10%. Only when the deviation rate of the fundamental voltage is not less than the preset deviation threshold is it considered that the voltage restorer needs to be activated to restore the power supply to the rated voltage. The fundamental equivalent impedance is a key parameter reflecting the load's fundamental energy consumption characteristics. It directly relates to the energy relationship between active power and voltage, and its function is to provide a basis for calculating the fundamental active power compensation. First, the fundamental equivalent impedance on the load side is calculated: Extracting the fundamental current amplitude on the grid side: Determine the fundamental phase based on the sinusoidal waveform of the load's rated fundamental voltage, select the time period that matches the fundamental phase from the current sliding time window, and calculate the root mean square value of the instantaneous value of the load's rated fundamental current during the time period as the actual fundamental current amplitude of the load. The ratio of the fundamental voltage amplitude on the grid side to the fundamental current amplitude on the grid side is used as the fundamental equivalent impedance on the load side. The fundamental active power compensation is calculated as follows: the square of the product of the fundamental voltage deviation rate, the fundamental compensation coefficient, and the actual fundamental voltage amplitude of the load, and the ratio of the fundamental equivalent impedance on the load side, is used as the fundamental active power compensation. This fundamental active power compensation is the active power value that the DVR needs to output to restore the fundamental voltage to the load demand level, providing a clear output command for the power conversion unit of the DVR. Similarly, the equivalent harmonic impedance of each target frequency on the load side is calculated. However, the load impedance of different frequency harmonics is significantly different. If a uniform impedance is used to calculate the compensation amount of all harmonics, it will lead to insufficient compensation of some frequency harmonics and failure to achieve harmonic suppression of all target frequencies. For the current harmonic components of each target frequency on the load side, their root mean square value is extracted as the current harmonic amplitude of the corresponding frequency. The ratio of the voltage harmonic amplitude to the current harmonic amplitude of the same frequency on the load side is used as the equivalent harmonic impedance of the target frequency. Calculate the harmonic active power compensation amount: The product of the harmonic compensation coefficient and the square of the equivalent amplitude of the voltage harmonic of the corresponding target frequency, and the ratio of this product to the equivalent impedance of the load-side harmonics at the target frequency, is used as the harmonic active power compensation amount for a single target frequency. Calculating this separately ensures that the compensation amount for each frequency matches its own needs. The compensation active power that matches the needs of each frequency is output independently, avoiding full compensation for all harmonics and improving load operating efficiency. Specifically, the DVR generates the compensation voltage signal corresponding to the frequency, and through power conversion, the compensation signals of each frequency are superimposed and synthesized to achieve the effect of frequency-based cancellation. The sum of the active power compensation amounts for each target frequency harmonic is used as the harmonic active power compensation amount, providing a complete basis for subsequent total compensation power calculation and energy storage allocation, thereby adjusting the compensation amount allocation ratio between the fundamental frequency and harmonics.

[0023] S4: Based on the comparison between the available active power of energy storage and the total compensation active power demand, adjust the allocation ratio of fundamental active power compensation and harmonic active power compensation. The available active power of the energy storage unit is affected by the remaining capacity and cannot meet the total compensation active power demand indefinitely. The importance of fundamental voltage stability and harmonic suppression to the load is hierarchical. Therefore, it is necessary to dynamically adjust the allocation ratio by comparing the available energy storage power with the total compensation demand. If the available active power of the energy storage is not less than the total compensation active power demand, the energy storage supply capacity fully covers the dual needs of fundamental voltage recovery and harmonic suppression. The allocation ratio of the fundamental active power compensation amount to the harmonic active power compensation amount is the ratio of the two, that is, there is no need to adjust the values ​​of the two. If the available active power of energy storage is less than the total compensation active power demand, but not less than the fundamental active power compensation amount, abandoning the proportional allocation will lead to continuous excessive harmonic pollution, increase load loss, and affect load operating efficiency. Therefore, the ratio of the fundamental active power compensation amount to the harmonic active power compensation amount is calculated first, and then the available active power of energy storage is allocated according to this ratio. The active power allocated to the fundamental is the available active power of energy storage multiplied by the proportion of the fundamental demand to the total demand, and the active power allocated to the harmonic is the available active power of energy storage multiplied by the proportion of the harmonic demand to the total demand. This ensures that the higher the proportion of the fundamental demand, the more power is allocated, while reserving reasonable active power for the harmonics and suppressing harmonic pollution as much as possible. If the available active power of energy storage is less than the fundamental active power compensation amount, the energy storage power can only meet the minimum requirements of fundamental compensation. Fundamental voltage stability is the core of load operation. Therefore, the allocation ratio of fundamental active power compensation amount to harmonic active power compensation amount is set to 1:0, that is, the available active power of energy storage is fully allocated to the fundamental active power compensation amount, ensuring that the load can still maintain basic operation when the energy storage power is extremely limited.

[0024] S5: Calculate the slope of the change in the fundamental voltage amplitude and the variance of the fundamental voltage deviation rate within the monitoring time interval, and adjust the fundamental compensation coefficient accordingly. Then, use the adjusted fundamental compensation coefficient to correct the total compensation active power demand. First, the monitoring interval is defined as follows: taking the current sliding time window as the ending window, it sequentially includes N-1 consecutive historical sliding time windows. All sliding windows are arranged in a continuous overlapping manner according to a preset sliding step size, where N is an integer from 2 to 4, covering at least 1 / 4 of a cycle and not exceeding one cycle, so as to quickly adjust the fundamental compensation coefficient. The duration of the sliding time window is not less than 5ms, and the sliding step size is 2ms. The number of sliding time windows for each sampling point in this monitoring time interval can be not less than 2, avoiding distortion caused by instantaneous disturbances in the power grid in a single window. The fundamental voltage amplitude and fundamental voltage deviation rate of the power grid side corresponding to each window in all sliding time windows in the monitoring time interval are obtained. For a single sliding time window, based on the sinusoidal waveform of the load's rated fundamental voltage, the period within the sliding time window where the fundamental phase is consistent is located. The instantaneous value of the load's rated fundamental voltage during this period is extracted and linearly fitted. The slope is used as the normal reference slope. The actual slope is obtained by linearly fitting the fundamental voltage component. The difference between the actual slope and the normal reference slope is used as the trend deviation of the sliding time window. The average of the trend deviations of all sliding time windows is used as the slope of the change in the fundamental voltage amplitude on the grid side. The core significance of this slope is to quantify the dynamic change direction and speed of the fundamental voltage. The result of the difference between the actual slope and the normal reference value reflects the degree of deviation and the significance of drop or rise. This phenomenon can be quantified by averaging multiple sliding time windows, and adjustments can be made accordingly. That is, the DVR has a certain predictive function for voltage change trends, avoiding continuous passive response to voltage deviations that have already occurred. Obtain the arithmetic mean of the fundamental voltage deviation rate corresponding to each sliding time window within all sliding time windows. Then, calculate the squared deviation of the fundamental voltage deviation rate of each window from the arithmetic mean. The arithmetic mean of all the squared deviations is taken as the variance of the fundamental voltage deviation rate in the monitoring time interval. The larger the variance, the more drastic the fluctuation of the fundamental voltage deviation rate in each window. Conversely, the smaller the variance, the more consistent the fundamental voltage deviation rate in each window tends to be, indicating that the voltage is in a stable state and no additional compensation is required.

[0025] The system presets a lower slope threshold, an upper slope threshold, and a variance benchmark value. Setting the lower and upper slope thresholds provides the conditions for initiating adjustments to the compensation coefficient, thus preventing frequent fluctuations. When the slope of the fundamental voltage amplitude change is less than the lower limit threshold, the fundamental compensation coefficient is increased by 5% to curb the voltage drop trend. When the slope of the fundamental voltage amplitude change is greater than the upper limit threshold, the fundamental compensation coefficient is decreased by 5% to prevent voltage overshoot from damaging the equipment. If the slope is between the lower and upper slope thresholds, the condition for adjusting the compensation coefficient is provided based on the variance benchmark value. By further analyzing the variance of the fundamental voltage deviation rate, voltage fluctuations are smoothed, voltage stability is improved, and the load's demand for stable power supply is met. Specifically, when the variance of the fundamental voltage deviation rate is greater than the variance benchmark value, the fundamental compensation coefficient is increased by 5%. The lower slope threshold is negative, the upper slope threshold is positive, the variance benchmark value is positive, and the deviation threshold is 10%. According to engineering experience, this is relatively stable. When the fundamental voltage deviation rate of the sliding time window within the monitoring time interval is less than the preset deviation threshold, the voltage restorer is exited. This ensures that the voltage stabilizes and meets the standard before timely exit, avoiding unlimited continuous compensation by the DVR. Only looking at the slope may ignore situations where the slope is normal but the fluctuation is severe. For example, if the voltage change rate is stable but the fundamental voltage deviation rate fluctuates, the voltage stability is poor, and the active power output needs to be increased.

[0026] Please see Figure 2 The present invention further provides a control device for the active power of a photoelectric storage magnetic reactance dynamic voltage restorer, used to execute the above-described control method for the active power of the photoelectric storage magnetic reactance dynamic voltage restorer, comprising: The data extraction module is used to define the current sliding time window based on the current moment, and to determine the fundamental voltage amplitude of the grid side, the actual fundamental voltage amplitude of the load, and the equivalent amplitude of the target frequency voltage harmonic of the load side based on the instantaneous voltage values ​​of the grid side and the load side within the current sliding time window, and to extract the available active power of energy storage at the current moment. The deviation calculation module is used to pre-set the fundamental compensation coefficient and harmonic compensation coefficient, calculate the fundamental voltage deviation rate based on the fundamental voltage amplitude of the grid side and the actual fundamental voltage amplitude of the load, and calculate the harmonic deviation rate by comparing the equivalent amplitude of the target frequency voltage harmonic with the actual fundamental voltage amplitude of the load. The demand extraction module is used to calculate the fundamental active power compensation amount based on the fundamental voltage deviation rate, fundamental compensation coefficient, and actual fundamental voltage amplitude of the load when the fundamental voltage deviation rate is not less than the preset deviation threshold. It also calculates the harmonic active power compensation amount based on the harmonic compensation coefficient and the equivalent amplitude of the harmonic harmonic of the target frequency voltage. The sum of the fundamental active power compensation amount and the harmonic active power compensation amount is taken as the total compensation active power demand. The power distribution module is used to compare the available active power of energy storage with the total compensation active power demand, and adjust the distribution ratio of the fundamental active power compensation amount and the harmonic active power compensation amount. The power regulation module is used to calculate the slope of the change in the amplitude of the fundamental voltage on the grid side and the variance of the fundamental voltage deviation rate within the monitoring time interval, and adjust the fundamental compensation coefficient accordingly. The adjusted fundamental compensation coefficient is then used to correct the total compensation active power demand.

[0027] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0028] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0029] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0030] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for controlling the active power of a photoelectric storage magnetic reactance type dynamic voltage restorer, characterized in that, The specific steps include: The current sliding time window is defined based on the current moment, and the amplitude of the grid-side fundamental voltage, the amplitude of the actual load fundamental voltage, and the equivalent amplitude of the target frequency voltage harmonics on the load side are determined based on the instantaneous values ​​of the grid-side voltage and the load-side voltage within the current sliding time window. The available active power of energy storage at the current moment is also extracted. The fundamental voltage compensation coefficient and harmonic compensation coefficient are preset. The fundamental voltage deviation rate is calculated based on the fundamental voltage amplitude of the grid side and the actual fundamental voltage amplitude of the load. The harmonic deviation rate is calculated by comparing the equivalent amplitude of the target frequency voltage harmonic with the actual fundamental voltage amplitude of the load. When the fundamental voltage deviation rate is not less than the preset deviation threshold, the fundamental active power compensation amount is calculated based on the fundamental voltage deviation rate, the fundamental compensation coefficient, and the actual fundamental voltage amplitude of the load. The harmonic active power compensation amount is calculated based on the harmonic compensation coefficient and the equivalent amplitude of the harmonic harmonic of the target frequency voltage. The sum of the fundamental active power compensation amount and the harmonic active power compensation amount is taken as the total compensation active power requirement. Based on the comparison between the available active power of energy storage and the total compensation active power demand, the allocation ratio of fundamental active power compensation and harmonic active power compensation is adjusted. Calculate the slope of the change in the fundamental voltage amplitude and the variance of the fundamental voltage deviation rate within the monitoring time interval, and adjust the fundamental compensation coefficient accordingly. Then, use the adjusted fundamental compensation coefficient to correct the total compensation active power demand. Within each sliding time window, the instantaneous values ​​of the grid-side voltage and the load-side voltage collected are respectively constructed into sequences; Extracting the fundamental voltage amplitude on the grid side: The fundamental phase is determined by the synchronous rotating coordinate system phase-locked method for the sequence of instantaneous voltage values ​​on the grid side. Several fundamental voltage components are separated from the sequence based on the fundamental phase, and the root mean square value of the fundamental voltage components is taken as the fundamental voltage amplitude on the grid side. Extracting the actual fundamental voltage amplitude of the load: Determine the fundamental phase based on the sinusoidal waveform of the rated fundamental voltage of the load, select the time period that is consistent with the fundamental phase from the current sliding time window, and calculate the root mean square value of the instantaneous value of the rated fundamental voltage of the load in the time period as the actual fundamental voltage amplitude of the load. The equivalent amplitude of the target frequency voltage harmonics is extracted: the short-time Fourier transform method is used to decompose the full frequency spectrum of the instantaneous voltage value sequence on the load side to obtain the harmonic spectrum distribution. The amplitudes of the 3rd, 5th and 7th harmonics are extracted under the harmonic spectrum distribution, and the ratio of the amplitude of each frequency to the amplitude of the actual fundamental voltage of the load is calculated. The frequencies with a ratio greater than 1% are taken as the target frequencies to extract several target frequency voltage harmonic components and obtain the target frequency current harmonic components. The power factor of voltage harmonics and current harmonics at each target frequency is collected. The product of the voltage harmonic component at the target frequency, the current harmonic component at the same frequency, and the power factor is taken as the active power of voltage harmonics at each target frequency. The proportion of the active power of voltage harmonics at each target frequency to the sum of the active power of voltage harmonics at all target frequencies is taken as a weighting coefficient. The amplitude of each target frequency harmonic is weighted and summed to obtain the equivalent amplitude of voltage harmonics at the target frequency. First, the fundamental equivalent impedance on the load side is calculated: Extract the amplitude of the fundamental current on the grid side: The fundamental phase is determined based on the sinusoidal waveform of the load's rated fundamental voltage. The time period that matches the fundamental phase is selected from the current sliding time window, and the root mean square value of the instantaneous value of the load's rated fundamental current during that time period is calculated as the actual fundamental current amplitude of the load. The ratio of the fundamental voltage amplitude on the grid side to the fundamental current amplitude on the grid side is used as the fundamental equivalent impedance on the load side. Calculate the fundamental active power compensation: The ratio of the square of the product of the fundamental voltage deviation rate, the fundamental compensation coefficient, and the actual fundamental voltage amplitude of the load to the fundamental equivalent impedance on the load side is used as the fundamental active power compensation amount. Calculate the equivalent harmonic impedance for each target frequency on the load side: For the current harmonic components of each target frequency on the load side, their root mean square values ​​are extracted as the current harmonic amplitude of the corresponding frequency, and the ratio of the voltage harmonic amplitude to the current harmonic amplitude of the same frequency on the load side is used as the harmonic equivalent impedance at that target frequency. Calculate the harmonic active power compensation amount: The product of the harmonic compensation coefficient and the square of the equivalent amplitude of the voltage harmonic at the corresponding target frequency, and the ratio of this product to the equivalent impedance of the load-side harmonic at the target frequency, are used as the harmonic active power compensation amount for a single target frequency. The sum of the harmonic active power compensation amounts for each target frequency is used as the harmonic active power compensation amount. If the available active power of energy storage is not less than the total compensation active power requirement, the allocation ratio of the fundamental active power compensation amount to the harmonic active power compensation amount is the ratio of the two, that is, there is no need to adjust the values ​​of the two. If the available active power of energy storage is less than the total compensation active power demand, but not less than the fundamental active power compensation amount, first calculate the ratio of the fundamental active power compensation amount to the harmonic active power compensation amount, and then allocate the available active power of energy storage according to this ratio. The active power allocated to the fundamental is the available active power of energy storage multiplied by the proportion of the fundamental active power compensation amount to the sum of the fundamental active power compensation amount and the harmonic active power compensation amount. The active power allocated to the harmonic is the available active power of energy storage multiplied by the proportion of the harmonic demand to the total demand. If the available active power of energy storage is less than the fundamental active power compensation amount, the allocation ratio of the fundamental active power compensation amount to the harmonic active power compensation amount is set to 1:0, that is, the available active power of energy storage is fully allocated to the fundamental active power compensation amount.

2. The method for controlling the active power of the photoelectric storage magnetic reactance type dynamic voltage restorer according to claim 1, characterized in that: The sliding time window ends at the current time and lasts for no less than 5ms, with a sliding step size of 2ms. The monitoring time interval is N-1 consecutive historical sliding time windows that terminate at the current sliding time window. All sliding windows are arranged in a continuous overlapping manner according to a preset sliding step size, where N is an integer from 2 to 4.

3. The method for controlling the active power of the photoelectric storage magnetic reactance type dynamic voltage restorer according to claim 1, characterized in that: The fundamental voltage deviation rate is calculated based on the fundamental voltage amplitude on the grid side and the actual fundamental voltage amplitude of the load. The harmonic deviation rate is calculated by comparing the equivalent amplitude of the target frequency voltage harmonics with the actual fundamental voltage amplitude of the load. Using the actual fundamental voltage amplitude of the load as a reference, the relative error between the fundamental voltage amplitude on the grid side and the reference is calculated as the fundamental voltage deviation rate. Using the actual fundamental voltage amplitude of the load as a reference, the ratio of the equivalent amplitude of the target frequency voltage harmonics to the reference is calculated as the harmonic deviation rate.

4. The method for controlling the active power of the photoelectric storage magnetic reactance type dynamic voltage restorer according to claim 1, characterized in that: The deviation threshold is 10%.

5. The method for controlling the active power of the photoelectric storage magnetic reactance type dynamic voltage restorer according to claim 1, characterized in that: The method for calculating the slope of the change in the fundamental voltage amplitude and the variance of the fundamental voltage deviation rate within the monitoring time interval is as follows: Obtain the fundamental voltage amplitude and fundamental voltage deviation rate of the grid side corresponding to all sliding windows within the monitoring time interval; For a single sliding time window, based on the sinusoidal waveform of the load's rated fundamental voltage, the period within the sliding time window where the fundamental phase is consistent is located. The instantaneous value of the load's rated fundamental voltage during this period is extracted and linearly fitted. The slope is used as the normal reference slope. The fundamental voltage component is linearly fitted to obtain the actual slope. The difference between the actual slope and the normal reference slope is used as the trend deviation of the sliding time window. The average trend deviation of all sliding time windows is used as the slope of the change in the fundamental voltage amplitude on the grid side. Obtain the fundamental voltage deviation rate corresponding to all sliding windows within the monitoring time interval, and use the calculated variance as the variance of the fundamental voltage deviation rate within the monitoring time interval.

6. The method for controlling the active power of the photoelectric storage magnetic reactance type dynamic voltage restorer according to claim 5, characterized in that: The method for adjusting the fundamental frequency compensation coefficient is as follows: Preset the lower and upper threshold values ​​for slope, and the variance baseline value; When the slope of the fundamental voltage amplitude change is less than the lower threshold of the slope, the fundamental voltage compensation coefficient is increased by 5%. When the slope of the fundamental voltage amplitude change is greater than the upper threshold of the slope, the fundamental voltage compensation coefficient is decreased by 5%. If the slope is between the lower threshold of the slope and the upper threshold of the slope, the variance of the fundamental voltage deviation rate is further analyzed. When the variance of the fundamental voltage deviation rate is greater than the variance benchmark value, the fundamental voltage compensation coefficient is increased by 5%. The lower threshold of the slope is negative, the upper threshold of the slope is positive, and the variance benchmark value is positive.

7. A control device for the active power of a photoelectric storage magnetic reactance type dynamic voltage restorer, characterized in that: The device is used to execute the active power control method of the photoelectric storage magnetic reactance dynamic voltage restorer according to any one of claims 1-6: The data extraction module is used to define the current sliding time window based on the current moment, and to determine the fundamental voltage amplitude of the grid side, the actual fundamental voltage amplitude of the load, and the equivalent amplitude of the target frequency voltage harmonic of the load side based on the instantaneous voltage values ​​of the grid side and the load side within the current sliding time window, and to extract the available active power of energy storage at the current moment. The deviation calculation module is used to pre-set the fundamental compensation coefficient and harmonic compensation coefficient, calculate the fundamental voltage deviation rate based on the fundamental voltage amplitude of the grid side and the actual fundamental voltage amplitude of the load, and calculate the harmonic deviation rate by comparing the equivalent amplitude of the target frequency voltage harmonic with the actual fundamental voltage amplitude of the load. The demand extraction module is used to calculate the fundamental active power compensation amount based on the fundamental voltage deviation rate, fundamental compensation coefficient, and actual fundamental voltage amplitude of the load when the fundamental voltage deviation rate is not less than the preset deviation threshold. It also calculates the harmonic active power compensation amount based on the harmonic compensation coefficient and the equivalent amplitude of the harmonic harmonic of the target frequency voltage. The sum of the fundamental active power compensation amount and the harmonic active power compensation amount is taken as the total compensation active power demand. The power distribution module is used to compare the available active power of energy storage with the total compensation active power demand, and adjust the distribution ratio of the fundamental active power compensation amount and the harmonic active power compensation amount. The power regulation module is used to calculate the slope of the change in the amplitude of the fundamental voltage on the grid side and the variance of the fundamental voltage deviation rate within the monitoring time interval, and adjust the fundamental compensation coefficient accordingly. The adjusted fundamental compensation coefficient is then used to correct the total compensation active power demand.

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