A distribution area voltage compensation control method and system considering distributed power fluctuation

Abstract

The application relates to the technical field of power distribution system control, in particular to a transformer area voltage compensation control method and system considering distributed power fluctuation, which specifically comprises the following steps: constructing power quality influence coefficients of each grid-connected point in each period according to data changes in voltage data rotating components of each grid-connected point in a low-voltage transformer area in each period and differences between positive, negative and zero sequence components obtained by three-phase voltage decomposition; calculating comprehensive disturbance coefficients of the low-voltage transformer area in each period in combination with voltage differences between different grid-connected points and voltage change trend synchronism; comprehensively considering distribution differences and coupling influence relationships between the grid-connected points, which can more accurately evaluate influence characteristics of the distributed power fluctuation; optimizing gain coefficients in a sliding mode controller based on the obtained comprehensive disturbance coefficients; and adopting the adjusted controller to perform transformer area voltage compensation control, which is helpful to make up for defects of insufficient transformer area voltage compensation accuracy and reliability.

Description

Technical Field

[0001] This application relates to the field of power distribution system control technology, specifically to a method and system for voltage compensation control of distribution transformer areas that takes into account fluctuations of distributed power sources. Background Technology

[0002] With the construction and development of new power distribution systems, the large-scale application of distributed power sources and energy storage has become an inevitable trend. Distribution substations are the basic units for low-voltage distribution management, line loss accounting, and customer service in power systems. As the scale of various distributed power sources and nonlinear loads continues to increase, power quality deteriorates, affecting the safe operation of electrical equipment. To address this issue, reactive and active power flow controllers (RPCs) or grid-connected inverters are typically used for reactive and active power regulation to compensate for substation voltage and ensure voltage stability for customers.

[0003] Considering the significant intermittency and fluctuation in the output of distributed power sources, rapid changes in their output power directly lead to rapid fluctuations and voltage exceedances along the grid connection point and distribution area. This effect is particularly sensitive and severe in low-voltage distribution areas with high impedance, and is also highly uncertain. Furthermore, the strong electrical coupling between multiple grid connection points means that the compensation action of a single node can interfere with the voltage of other nodes, easily causing control conflicts or oscillations. Traditional voltage control methods are ill-suited to the nonlinearity and coupling characteristics of the power grid, and under the influence of these factors, they are prone to deficiencies in the accuracy and reliability of distribution area voltage compensation. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a method and system for voltage compensation control of distribution transformer areas that takes into account fluctuations in distributed power sources. The specific technical solution adopted is as follows:

[0005] In a first aspect, embodiments of this application provide a method for voltage compensation control of distribution transformer areas that takes into account fluctuations in distributed power sources. The method includes the following steps:

[0006] Real-time acquisition of three-phase voltage data at each grid connection point in the low-voltage distribution area;

[0007] The inherent time scale decomposition technique is used to decompose the single-phase voltage data of each grid-connected point in each time period. At the same time, the symmetrical component method is used to decompose the three-phase voltage of each grid-connected point in each time period. For each rotating component obtained by the signal decomposition, it is divided according to the point of maximum data change. The degree of difference between the two parts of data obtained by the division in each rotating component and the difference between the three components obtained by the symmetrical component method are analyzed to determine the power quality influence coefficient of the three-phase voltage data of each grid-connected point in each time period.

[0008] Calculate the per-unit voltage value of each grid connection point at each time; construct the coupling influence value of each grid connection point in each time period based on the difference in per-unit voltage values ​​between different grid connection points in each time period and the synchronization of voltage data change trends; and calculate the comprehensive disturbance coefficient of the low-voltage distribution area in each time period in combination with the power quality influence coefficient.

[0009] The gain coefficient of the controller is adjusted based on the comprehensive disturbance coefficient, and the adjusted controller is used for voltage compensation control of the transformer area.

[0010] In one embodiment, the process of obtaining the power quality influence coefficient is as follows:

[0011] Calculate the difference between the mean values ​​of the two parts of data obtained from the division in each rotating component, and denote it as the first difference; determine the low-frequency components in the rotating component; denote the fusion value of the first difference of all low-frequency components of the single-phase voltage of each grid connection point in each time period as the voltage sag characteristic significance coefficient.

[0012] The significant unbalance values ​​of the three-phase voltage at each grid connection point in each time period are constructed based on the differences between the moduli of the three components obtained by the symmetrical component decomposition method.

[0013] The power quality influence coefficients of the three-phase voltage data of each grid connection point in each time period are determined based on the voltage sag characteristic significance coefficient and the imbalance significance value. The power quality influence coefficients are positively correlated with the voltage sag characteristic significance coefficient and the imbalance significance value, respectively.

[0014] In one embodiment, the process of obtaining the significant imbalance value is as follows:

[0015] Calculate the difference between the magnitude of the negative-order component and the magnitude of the positive-order component, and the difference between the magnitude of the zero-order component and the magnitude of the positive-order component, respectively, for the three components obtained by the symmetric component decomposition, and then average the two to obtain the unbalanced significance value.

[0016] In one embodiment, the process of obtaining the coupling influence value is as follows:

[0017] The voltage deviation of each grid connection point in each time period is calculated based on the difference in voltage per unit value between each grid connection point and other grid connection points in each time period; the correlation coefficient between the voltage per unit value of each grid connection point and other grid connection points in each time period is calculated using a correlation algorithm.

[0018] The degree of coupling influence of each grid connection point in each time period is determined based on the voltage deviation and the correlation coefficient.

[0019] In one embodiment, the process of obtaining the degree of voltage deviation is as follows:

[0020] Calculate the average per-unit voltage value of each grid connection point at all times within each time period, and calculate the difference between the average per-unit voltage value of each grid connection point and the average per-unit voltage value of each other grid connection points within each time period, which is denoted as the second difference;

[0021] The voltage deviation of each grid connection point within each time period is the average of all the second differences of each grid connection point within each time period.

[0022] In one embodiment, the degree of coupling influence is positively correlated with the degree of voltage deviation and the correlation coefficient, respectively.

[0023] In one embodiment, the comprehensive disturbance coefficient is positively correlated with the coupling influence of all grid-connected points in the distribution area and the power quality influence coefficient in each time period.

[0024] In one embodiment, the expression for adjusting the gain coefficient of the controller based on the integrated disturbance coefficient is:

[0025]

[0026] In the formula, P is the adjusted gain coefficient. , These represent the maximum and minimum values ​​of the gain coefficient, respectively, and R is the normalized mean of the comprehensive disturbance coefficients for all time periods within the current detection window.

[0027] In one embodiment, the process of using the adjusted controller to perform substation voltage compensation control is as follows:

[0028] Calculate the power factor of the transformer substation within each preset detection window. If the power factor obtained in the current detection window is lower than the preset threshold, or if the per-unit voltage value of any grid-connected point in the transformer substation exceeds the preset safety range at the current moment, then the adjusted gain coefficient of the current detection window is used as the gain coefficient of the controller in the next detection window to compensate for the voltage of the transformer substation.

[0029] Secondly, embodiments of this application also provide a transformer area voltage compensation control system that takes into account distributed power source fluctuations, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0030] The embodiments of this application have at least the following beneficial effects:

[0031] This application collects three-phase voltage data from each grid-connected point in a low-voltage distribution area in real time. It obtains the rotating components of the grid-connected point voltage data within each time period using a signal decomposition algorithm. By analyzing the differences in data before and after the mid-to-high frequency rotating components, it reflects the voltage sag characteristics of the grid-connected point. Simultaneously, it decomposes the three-phase voltage of each grid-connected point within each time period using the symmetrical component method. By analyzing the differences between the positive-sequence, negative-sequence, and zero-sequence components obtained from the decomposition, it reflects the unbalance characteristics of the three-phase current at the grid-connected point. Combining these two methods, it constructs the power quality influence coefficient for each grid-connected point within each time period. It analyzes the per-unit voltage differences and the synchronization of voltage data change trends between different grid-connected points within each time period. Combined with the power quality influence coefficient, it calculates the comprehensive disturbance coefficient of the low-voltage distribution area for each time period. This comprehensive consideration of the distribution differences and coupling effects between grid-connected points enables a more accurate assessment of the impact characteristics of distributed power source fluctuations. Based on the obtained comprehensive disturbance coefficient, it optimizes the gain coefficient in the sliding diaphragm controller and uses the adjusted controller for distribution area voltage compensation control, which helps to compensate for the deficiencies in the accuracy and reliability of distribution area voltage compensation. Attached Figure Description

[0032] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A flowchart illustrating the steps of a transformer area voltage compensation control method considering distributed power source fluctuations provided in one embodiment of this application;

[0034] Figure 2 This is a schematic diagram illustrating the process of obtaining the power quality influence coefficient. Detailed Implementation

[0035] To further illustrate the technical means and effects adopted by this application to achieve the intended inventive objective, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the transformer area voltage compensation control method and system considering distributed power source fluctuations proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0037] The following description, in conjunction with the accompanying drawings, details the specific scheme of the distribution voltage compensation control method and system for considering distributed power source fluctuations provided in this application.

[0038] Please see Figure 1 The diagram illustrates a flowchart of a transformer substation voltage compensation control method considering distributed power source fluctuations according to an embodiment of this application. The method includes the following steps:

[0039] Step S1: Collect three-phase voltage data of each grid connection point in the low-voltage distribution area in real time.

[0040] A low-voltage distribution area refers to a low-voltage region supplied by one or more distribution transformers. Its core structure typically consists of load units, high-voltage incoming lines, distribution transformers, low-voltage outgoing lines, and related protection and control equipment. Considering that fluctuations in distributed power sources directly affect the voltage stability of the grid connection points, this application uses smart meters to acquire real-time three-phase voltage data for each grid connection point in the low-voltage distribution area to monitor power quality. In this embodiment, the voltage data sampling frequency is set to 2kHz. In other embodiments of this application, the implementer can set the voltage data sampling frequency according to actual conditions.

[0041] Step S2: The inherent time scale decomposition technique is used to decompose the single-phase voltage data of each grid connection point in each time period. At the same time, the symmetrical component method is used to decompose the three-phase voltage of each grid connection point in each time period. For each rotating component obtained by the signal decomposition, it is divided according to the maximum value of data change. The degree of difference between the two parts of data obtained by the division in each rotating component and the difference between the three components obtained by the symmetrical component method are analyzed to determine the power quality influence coefficient of the three-phase voltage data of each grid connection point in each time period.

[0042] Distribution networks with a high proportion of distributed generation connected to the grid face numerous operational risks. While voltage compensation control in distribution areas is an effective measure to mitigate these risks, its effectiveness is susceptible to the uncertainties of distributed generation fluctuations and the coupling relationships between grid connection points. Therefore, the following analysis addresses these influencing characteristics.

[0043] First, the prerequisite for effective voltage compensation and management in distribution transformer areas is a precise assessment of the power quality status within those areas. As the scale of distributed power sources and nonlinear loads continues to increase, the structure of distribution transformer areas becomes more complex, leading to more severe voltage sags and three-phase imbalances. These issues affect grid stability and equipment safety. Furthermore, the response rate of compensation control varies under different power quality conditions, significantly interfering with the effectiveness of voltage compensation.

[0044] When a voltage sag occurs, the voltage data waveform at the grid connection point will show a momentary drop in voltage amplitude, recovering after tens to hundreds of milliseconds, accompanied by a certain degree of harmonic distortion. Because the voltage data of low-voltage distribution substations exhibits strong nonlinear and non-stationary characteristics, containing composite signals with multiple frequency components, conventional time-domain analysis methods are insufficient for effective and accurate feature extraction. This application employs Inherent Time Scale Decomposition (ITD) to decompose the acquired voltage data into rotating components of different scales, thereby separating the transient characteristics of the voltage sag event from the power frequency background. Specifically, taking single-phase voltage data at a certain grid connection point as an example, a sampling period of 1 second is set. The single-phase voltage data at that grid connection point within one sampling period is used as the input to the ITD algorithm. The number of rotating components is set to 8, and the output is the decomposed rotating components. The Inherent Time Scale Decomposition (ITD) technique is a known technique, and its specific process will not be elaborated further.

[0045] The sudden energy generated by voltage sags is mainly concentrated in the mid-to-low frequency band. The rotational components in the mid-to-low frequency band experience significant rises or falls near the sag event. Therefore, in this embodiment, the last five rotational components are selected as the mid-to-low frequency rotational components for subsequent processing. It should be noted that implementers can determine the selection range of the mid-to-low frequency rotational components according to actual conditions; this application does not impose specific restrictions. Taking any rotational component in the mid-to-low frequency band as an example, firstly, the first-order difference sequence of the rotational component is calculated. Each value in this difference sequence reflects the degree of difference between adjacent data in the component. Therefore, the time when the absolute value of the element in the first-order difference sequence reaches its maximum value is taken as the approximate time of the voltage sag event. There is a significant amplitude difference between the rotational component data on the left and right sides of the approximate time. Therefore, the maximum value is used as the dividing point to divide the rotational component into left and right parts. The mean of all data on the left side and the mean of all data on the right side of the dividing point are calculated respectively. The difference between these two means is recorded as the first difference, which reflects the step jump characteristic of the rotational component. The difference can be the absolute value of the difference, the square of the difference, etc. In this embodiment, the first difference is the absolute value of the difference between the two means.

[0046] Further, the positive fusion value of the first difference among all mid- and low-frequency rotating components of the single-phase voltage at each grid connection point within each time period is calculated as the voltage sag characteristic significance coefficient A of the single-phase voltage at each grid connection point within each time period. This significance coefficient reflects the degree to which the single-phase voltage is affected by voltage sag within a certain time period. Here, "positive fusion" refers to combining two or more indicators by addition or multiplication. Preferably, in this embodiment, the positive fusion of the first difference among all mid- and low-frequency rotating components is the sum of the first differences among all mid- and low-frequency rotating components.

[0047] Furthermore, to obtain the three imbalance characteristics under the influence of distributed generation fluctuations, this application uses the symmetrical component method to decompose the three-phase voltage data of each grid-connected point within a certain time period, obtaining the positive-sequence component, negative-sequence component, and zero-sequence component of the three-phase voltage of the grid-connected point during that time period. The results of each component are represented by complex numbers. When the influence of distributed generation fluctuations is small, the three-phase voltage is relatively balanced, and the obtained negative-sequence and zero-sequence components will be smaller. Conversely, if the magnitude of the obtained negative-sequence or zero-sequence component is higher, it indicates that the three-phase imbalance characteristics of the corresponding time period are more obvious. The magnitude of the positive-sequence component is relatively stable under different states, but in actual power systems, the magnitude of the corresponding positive-sequence component will not be 0. Therefore, the ratio of the magnitude of the negative-sequence component to the magnitude of the positive-sequence component, and the ratio of the magnitude of the zero-sequence component to the magnitude of the positive-sequence component of the three-phase voltage of the grid-connected point during that time period are calculated respectively. The average of the two ratios is taken as the significant imbalance value C of the three-phase voltage of the grid-connected point during that time period. The significant imbalance value reflects the imbalance characteristics of the three-phase current of the grid-connected point under a certain time period.

[0048] Based on the above analysis, the power quality influence coefficient of the three-phase voltage data at each grid connection point in each time period is calculated. This power quality influence coefficient is positively correlated with both the voltage sag characteristic significance coefficient and the imbalance significance value. Preferably, in this embodiment, the expression for the power quality influence coefficient is:

[0049]

[0050] In the formula, The power quality impact coefficient is the three-phase voltage data of the b-th grid connection point in the a-th time period. It is the average value of the voltage sag characteristic significance coefficients of the three single-phase voltages at the b-th grid connection point during the a-th time period; The significant unbalance value of the three-phase voltage at the b-th grid connection point during the a-th time period; This is the normalized function. The result is... The larger the value, the greater the impact on the power quality of the grid-connected point during that period. In this embodiment, the normalization function used is maximum-minimum normalization, which normalizes the product of B and C for all grid-connected points across all time periods, obtaining the normalized value of the product of B and C for each grid-connected point in each time period. It should be noted that, when performing maximum-minimum normalization calculations, to prevent the denominator from being zero due to consistent data, a very small positive number is added to the denominator. To avoid the inability to perform normalization properly, this embodiment will... Set to 0.01.

[0051] In other embodiments of this application, the expression for the power quality influence coefficient may also be: ,in, for The normalized value, for The normalized value.

[0052] Parameter B analyzes the step jump characteristics of the rotating component obtained by ITD decomposition technology to assess the magnitude of the voltage sag at the grid connection point. Parameter C reflects the three-phase imbalance characteristics of the voltage data corresponding to the grid connection point, thereby comprehensively assessing the degree of power quality disturbance at the grid connection point during a specific period.

[0053] Step S3: Calculate the per-unit voltage value of each grid connection point at each time. Based on the differences in per-unit voltage values ​​between different grid connection points in each time period and the synchronization of voltage data change trends, construct the coupling influence value of each grid connection point in each time period. Combined with the power quality influence coefficient, calculate the comprehensive disturbance coefficient of the low-voltage distribution area in each time period.

[0054] Furthermore, with the integration of distributed generation in low-voltage distribution areas, voltage exceedance issues are more likely to occur at grid connection points. Generally, exceedance problems accumulate gradually from the power source side towards the end load, meaning the voltage at the grid connection point exhibits a gradually increasing distribution along the power flow direction. Severe voltage exceedances affect the stable operation of the power grid. Moreover, the voltage states of each grid connection point are closely linked under the influence of power flow, and the distribution of exceedance problems dynamically changes with the output fluctuations of distributed generation, exhibiting a more complex spatial distribution characteristic due to the coupling effect between grid connection points. For example, when the output of a distributed generation exceeds the local load, the excess power will be fed back towards the power source side, forming a reverse power flow. This complex voltage exceedance distribution directly interferes with the accuracy of subsequent voltage compensation control.

[0055] Therefore, firstly, the per-unit voltage value of each grid-connected point at each time point is calculated. The per-unit voltage value is the ratio of the measured voltage to the reference voltage, and ideally, the per-unit voltage value is 1. Then, the average per-unit voltage value of each grid-connected point at all times within each time period is obtained. The difference between the average per-unit voltage value of each grid-connected point and every other grid-connected point within a certain time period is calculated and denoted as the second difference. In this embodiment, the second difference is specifically the absolute value of the difference between the average per-unit voltage values. Then, the mean value S of the second difference between each grid-connected point and all other grid-connected points within a certain time period is calculated. This mean value reflects the degree of voltage deviation between different grid-connected points.

[0056] Furthermore, the maximum mutual information coefficient (MIC) between the voltage per-unit values ​​of the grid-connected point and all other grid-connected points within each time period is calculated. The MIC value ranges from [0,1], with a closer value to 1 indicating a stronger correlation between the two. The average of all the maximum mutual information coefficients is used as the coupling influence coefficient F of the grid-connected point for that time period. The larger the coupling influence coefficient, the stronger the synchronization between the voltage change of the grid-connected point and the change trend of other grid-connected points, i.e., the more significant the influence of network coupling. The calculation of the maximum mutual information coefficient is a well-known technique, and the specific process will not be elaborated further.

[0057] It should be noted that this application provides only one correlation algorithm for calculating the correlation coefficient between the per-unit voltage values ​​of different grid-connected points within a single time period. There are many existing correlation algorithms, and implementers may also use other correlation algorithms, such as Spearman correlation coefficient, Kendall correlation coefficient, etc., to calculate the correlation coefficient between the per-unit voltage values ​​of different grid-connected points within a single time period. This application does not impose any specific restrictions.

[0058] Therefore, the degree of coupling impact caused by distributed power source fluctuations at each grid connection point within a certain time period is calculated. This degree of coupling impact is positively correlated with both the second difference and the maximum mutual information coefficient. Preferably, in this embodiment, the expression for the degree of coupling impact is:

[0059]

[0060] In the formula, This represents the degree of coupling influence of the b-th grid connection point during the a-th time period; The mean of the second difference between the b-th grid connection point and all other grid connection points during the a-th time period; The maximum mutual information coefficient between the per-unit voltage values ​​of the b-th grid connection point and all other grid connection points during the a-th time period; This is the normalized function. The result is... The larger the value, the more pronounced the complex distribution differences and coupling effects of the grid-connected point voltages within that time period. In this embodiment, the normalization function used is the maximum-minimum normalization, which normalizes the product of S and F for all grid-connected points across all time periods, obtaining the normalized value of the product of S and F for each grid-connected point in each time period. It should be noted that, when performing the maximum-minimum normalization calculation, a very small positive number is added to the denominator to prevent the denominator from being zero due to consistent data. To avoid the inability to perform normalization properly, this embodiment will... Set to 0.01.

[0061] In other embodiments of this application, the expression for the coupling influence degree value may also be: In the formula, for The normalized value, for The normalized value.

[0062] Parameter S assesses the degree of difference in voltage between the grid connection point and other grid connection points in the spatial dimension, while parameter F reflects the strength of the dynamic correlation between the voltage of the grid connection point and other grid connection points. Grid connection points with a larger H are often nodes that are more severely affected by distributed generation fluctuations.

[0063] Therefore, it can be seen that the fluctuations of distributed generation sources may significantly interfere with the power quality and spatial distribution of voltage exceedances at each grid-connected point in the distribution area. During the voltage compensation control process in the distribution area, the transformer needs to be adjusted according to the actual voltage conditions at the grid-connected points. The response rate of the adjustment varies depending on the degree of influence of the distributed generation source fluctuations. Therefore, based on the power quality influence coefficient and coupling influence value of all grid-connected points in each time period, the comprehensive disturbance coefficient of the corresponding voltage state of the low-voltage distribution area in each time period is calculated. Preferably, in this embodiment, the expression for the comprehensive disturbance coefficient is:

[0064]

[0065] In the formula, is the comprehensive disturbance coefficient of the low-voltage distribution area in the a-th time period; N represents the total number of grid connection points in the low-voltage distribution area; , These are the first weighting coefficient and the second weighting coefficient, respectively. The power quality impact coefficient is the three-phase voltage data of the b-th grid connection point in the a-th time period. Let be the coupling influence value of the b-th grid connection point in the a-th time period. This embodiment sets , The values ​​are all 0.5, in order to... and The products are added with equal weights. In other embodiments of this application, the implementer may set the weights according to the actual situation. , The larger the value of L, the worse the voltage condition of each grid connection point in the low-voltage distribution area during that period.

[0066] In other embodiments of this application, the expression for the comprehensive disturbance coefficient may also be: .

[0067] Step S4: Adjust the gain coefficient of the controller based on the comprehensive disturbance coefficient, and use the adjusted controller to perform voltage compensation control for the transformer area.

[0068] This application conducts an in-depth analysis of the power quality of each grid connection point in a low-voltage distribution area and the coupling relationship between these points, thereby accurately assessing the impact of distributed power source fluctuations. Due to the high impedance of the low-voltage distribution area, this application utilizes a power flow controller (RPC) for voltage compensation control. This voltage compensation control involves an inverter generating a compensation voltage synchronized with the system voltage but with adjustable amplitude and phase. The inverter employs a sliding mode controller to generate a PWM control signal, thereby precisely controlling the output compensation voltage. The sliding mode controller maintains millisecond-level real-time voltage tracking control. The gain coefficient of the sliding mode controller determines the dynamic response performance of the system. A larger overall disturbance coefficient indicates that distributed power source output fluctuations cause significant deviations in the grid connection point voltage. In this case, setting a high gain coefficient improves the controller's dynamic response speed and better suppresses external disturbances. Conversely, a smaller overall disturbance coefficient indicates relatively good voltage at each grid connection point in the distribution area, allowing for a smaller gain coefficient to avoid system chattering.

[0069] Specifically, the first step is to determine whether the power factor of the distribution area is within the allowable fluctuation range. To avoid over-adjustment caused by instantaneous fluctuation interference, a detection window is set. In this embodiment, the duration of a single detection window is set to 15 minutes. The power factor of the low-voltage distribution area in each detection window is calculated. The calculation of the power factor is a well-known technique, and the specific process will not be described in detail.

[0070] If the power factor obtained in the current detection window is lower than the preset threshold M (in this embodiment, M is set to 0.9) or the per-unit voltage value of any grid-connected point in the transformer area exceeds the preset safety range (in this embodiment, it is set to [0.95, 1.05]) at the current moment, voltage compensation adjustment is performed in a timely manner via RPC. During the voltage compensation adjustment process, the gain coefficient of the sliding diaphragm controller in the next detection window is adjusted by the comprehensive disturbance coefficient of all time periods in the current detection window. The power factor calculation is a well-known technique, and the specific process will not be elaborated further. In this embodiment, the threshold M is set to 0.9, and the safety range is set to [0.95, 1.05]. In other embodiments of this application, the implementer can set the threshold M and the safety range according to the actual situation.

[0071] This application uses a trial-and-error method to obtain the range of values ​​for the gain coefficient, denoted as [ The maximum-minimum normalization method is used to normalize the comprehensive disturbance coefficients for all time periods. Based on the normalized values ​​of the comprehensive disturbance coefficients, the gain coefficient of the sliding diaphragm controller is adjusted. The expression is as follows:

[0072]

[0073] In the formula, P is the adjusted gain coefficient. , These represent the maximum and minimum values ​​of the gain coefficient, respectively, and R is the mean of the normalized values ​​of the comprehensive disturbance coefficient across all time periods within the current detection window. The adjusted gain coefficient calculated in the current detection window is used as the gain coefficient of the sliding mode controller in the next detection window. The PWM control signal output by the sliding mode controller is obtained, and the compensation voltage is output through the inverter, which helps to compensate for the insufficient accuracy and reliability of voltage compensation in the transformer substation.

[0074] A schematic diagram illustrating the process of obtaining the power quality influence coefficient is shown below. Figure 2 As shown.

[0075] Based on the same inventive concept as the above methods, embodiments of this application also provide a transformer area voltage compensation control system that considers distributed power source fluctuations, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described transformer area voltage compensation control methods that consider distributed power source fluctuations.

[0076] In summary, this application provides a distribution area voltage compensation control method considering distributed power source fluctuations. It collects three-phase voltage data from each grid-connected point in a low-voltage distribution area in real time, obtains the rotating components of the grid-connected point voltage data within each time period using a signal decomposition algorithm, analyzes the differences between data before and after the mid-to-high frequency rotating components to reflect the voltage sag characteristics of the grid-connected point, and simultaneously decomposes the three-phase voltage of each grid-connected point within each time period using a symmetrical component method. It analyzes the differences between the obtained positive-sequence, negative-sequence, and zero-sequence components to reflect the unbalance characteristics of the three-phase current at the grid-connected point. Combining these two methods, it constructs a power quality influence coefficient for each grid-connected point within each time period. It analyzes the per-unit voltage differences and the synchronization of voltage data change trends between different grid-connected points within each time period, and calculates the comprehensive disturbance coefficient of the low-voltage distribution area for each time period based on the power quality influence coefficient. By comprehensively considering the distribution differences and coupling effects between grid-connected points, it can more accurately assess the impact characteristics of distributed power source fluctuations. Based on the obtained comprehensive disturbance coefficient, it optimizes the gain coefficient in the sliding diaphragm controller and uses the adjusted controller for distribution area voltage compensation control, which helps to compensate for the deficiencies in the accuracy and reliability of distribution area voltage compensation.

[0077] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this application. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0078] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0079] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A method for voltage compensation control of distribution transformer areas considering distributed power source fluctuations, characterized in that, The method includes the following steps: Real-time acquisition of three-phase voltage data at each grid connection point in the low-voltage distribution area; The inherent time scale decomposition technique is used to decompose the single-phase voltage data of each grid-connected point in each time period. At the same time, the symmetrical component method is used to decompose the three-phase voltage of each grid-connected point in each time period. For each rotating component obtained by the signal decomposition, it is divided according to the point of maximum data change. The degree of difference between the two parts of data obtained by the division in each rotating component and the difference between the three components obtained by the symmetrical component method are analyzed to determine the power quality influence coefficient of the three-phase voltage data of each grid-connected point in each time period. Calculate the per-unit voltage value of each grid connection point at each time; construct the coupling influence value of each grid connection point in each time period based on the difference in per-unit voltage values ​​between different grid connection points in each time period and the synchronization of voltage data change trends; and calculate the comprehensive disturbance coefficient of the low-voltage distribution area in each time period in combination with the power quality influence coefficient. The gain coefficient of the controller is adjusted based on the comprehensive disturbance coefficient, and the adjusted controller is used for transformer area voltage compensation control. The process for obtaining the power quality influence coefficient is as follows: Calculate the difference between the mean values ​​of the two parts of data obtained from the division in each rotating component, and denote it as the first difference; determine the low-frequency components in the rotating component; denote the fusion value of the first difference of all low-frequency components of the single-phase voltage of each grid connection point in each time period as the voltage sag characteristic significance coefficient. The significant unbalance values ​​of the three-phase voltage at each grid connection point in each time period are constructed based on the differences between the moduli of the three components obtained by the symmetrical component decomposition method. Based on the voltage sag characteristic significance coefficient and the unbalance significance value, the power quality influence coefficient of the three-phase voltage data of each grid connection point in each time period is determined. The power quality influence coefficient is positively correlated with the voltage sag characteristic significance coefficient and the unbalance significance value, respectively. The process for obtaining the coupling influence value is as follows: The voltage deviation of each grid connection point in each time period is calculated based on the difference in voltage per unit value between each grid connection point and other grid connection points in each time period; the correlation coefficient between the voltage per unit value of each grid connection point and other grid connection points in each time period is calculated using a correlation algorithm. The degree of coupling influence of each grid connection point in each time period is determined based on the voltage deviation and the correlation coefficient. The expression for adjusting the controller gain coefficient based on the integrated disturbance coefficient is as follows: ； In the formula, P is the adjusted gain coefficient. , These represent the maximum and minimum values ​​of the gain coefficient, respectively, and R is the normalized mean of the comprehensive disturbance coefficients for all time periods within the current detection window.

2. The transformer area voltage compensation control method considering distributed power source fluctuations as described in claim 1, characterized in that, The process for obtaining the significant imbalance value is as follows: Calculate the difference between the magnitude of the negative-order component and the magnitude of the positive-order component, and the difference between the magnitude of the zero-order component and the magnitude of the positive-order component, respectively, for the three components obtained by the symmetric component decomposition, and then average the two to obtain the unbalanced significance value.

3. The transformer area voltage compensation control method considering distributed power source fluctuations as described in claim 1, characterized in that, The process for obtaining the degree of voltage deviation is as follows: Calculate the average per-unit voltage value of each grid connection point at all times within each time period, and calculate the difference between the average per-unit voltage value of each grid connection point and the average per-unit voltage value of each other grid connection points within each time period, which is denoted as the second difference; The voltage deviation of each grid connection point within each time period is the average of all the second differences of each grid connection point within each time period.

4. The transformer area voltage compensation control method considering distributed power source fluctuations as described in claim 1, characterized in that, The degree of coupling influence is positively correlated with the degree of voltage deviation and the correlation coefficient, respectively.

5. The transformer area voltage compensation control method considering distributed power source fluctuations as described in claim 1, characterized in that, The comprehensive disturbance coefficient is positively correlated with the coupling influence degree of all grid-connected points in the substation area and the power quality influence coefficient in each time period.

6. The transformer area voltage compensation control method considering distributed power source fluctuations as described in claim 1, characterized in that, The process of using the adjusted controller to perform substation voltage compensation control is as follows: Calculate the power factor of the transformer substation within each preset detection window. If the power factor obtained in the current detection window is lower than the preset threshold, or if the per-unit voltage value of any grid-connected point in the transformer substation exceeds the preset safety range at the current moment, then the adjusted gain coefficient of the current detection window is used as the gain coefficient of the controller in the next detection window to compensate for the voltage of the transformer substation.

7. A distribution transformer voltage compensation control system considering distributed power source fluctuations, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-6.

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