Active fusion management system applied to high proportion photovoltaic access area power grid

Abstract

This application relates to the field of power grid security management technology, specifically to an active integration management system for distribution network power grids with high photovoltaic (PV) integration. This system includes: a power grid dynamic monitoring module: acquiring power flow distribution maps of the distribution network power grid at various times, collecting three-phase voltages in the power grid lines at various times, and the output power of each PV power generation system at various times; a power flow calculation module: determining the power flow increment from each PV power generation system to each power grid line; determining the power flow coordination coefficient between each PV power generation system and each power grid line; and acquiring the power flow radiation lines of each PV power generation system; and a distribution network power grid integration management module: acquiring the power flow disorder of each power flow radiation line; determining the three-phase imbalance of each power flow radiation line; comprehensively evaluating each power flow radiation line belonging to the trunk line; acquiring the key sections of the distribution network power grid; and actively integrating and managing the distribution network power grid. This application improves the security, stability, and power supply quality of the distribution network power grid.

Description

Technical Field

[0001] This application relates to the field of power grid security governance technology, specifically to an active integrated governance system for distribution grids with a high proportion of photovoltaic grid integration. Background Technology

[0002] With the increasing global demand for clean energy, the installation scale of new energy power generation systems in distribution networks is rapidly expanding, and their application in power systems is becoming increasingly widespread. However, as the penetration rate of photovoltaic power generation in power systems continues to increase, photovoltaic power generation itself has problems such as randomness and intermittency. In particular, with a large number of distributed photovoltaic power sources connected to low-voltage distribution area grids, the traditional distribution network is transformed from a passive network to an active network, making the power flow path and distribution of the distribution system more complex, resulting in prominent power quality problems such as voltage fluctuations and voltage flicker in the distribution system.

[0003] With the current situation of large-scale, high-proportion distributed renewable energy being integrated into the power grid of distribution substations, the cost of rapidly tracking and responding to changes in renewable energy output is high. The high penetration rate of renewable energy not only causes power flow reversal but also leads to heavy or overloaded operation of distribution lines, increasing additional dispatch costs and limiting the consumption of renewable energy. At the same time, the disorderly integration of a large number of single-phase distributed photovoltaic systems will significantly exacerbate the three-phase imbalance of the power grid in distribution substations, resulting in problems with low power supply reliability and security. Summary of the Invention

[0004] To address the aforementioned technical issues, this application provides an active integrated management system for distribution grids with high photovoltaic grid integration, thereby resolving the existing problems.

[0005] The active integration and governance system for distribution grids with high photovoltaic coverage in this application adopts the following technical solution:

[0006] One embodiment of this application provides an active integration and governance system for distribution grids with high photovoltaic integration, the system comprising:

[0007] Power Grid Dynamic Monitoring Module: Used to obtain the power flow distribution map of the power grid at various times based on the topology map of the power grid in the distribution area, collect the three-phase voltage of the lines in the power grid at various times, and the output power of each photovoltaic power generation system at various times.

[0008] Power flow calculation module: Based on the power flow distribution map of the peak power generation time of the photovoltaic power generation system, it obtains the shortest reachable path from each photovoltaic power generation system to each power grid line; analyzes the power change between adjacent power grid lines in the shortest reachable path, and determines the power flow increment from each photovoltaic power generation system to each power grid line;

[0009] The power output of each photovoltaic power generation system during peak power generation is analyzed to compare with the power output of each power grid line during the same period, and the power flow coordination coefficient between each photovoltaic power generation system and each power grid line is determined. Based on the number of lines in the shortest reachable path, the power flow increment, and the power flow coordination coefficient, each power grid line is comprehensively evaluated to obtain the power flow radiation lines of each photovoltaic power generation system.

[0010] The integrated governance module for power grids in the distribution area is used to determine the power flow change of each power flow radiation line by measuring the power change of each power line in the local neighborhood of each power flow radiation line at adjacent times. Combined with the number of power lines in the local neighborhood of each power flow radiation line that experience power flow reversal at adjacent times, the power flow disorder of each power flow radiation line is obtained.

[0011] Based on the degree of deviation between the three-phase voltages at each moment in each power flow radiation line, the three-phase imbalance of each power flow radiation line is determined; the number of photovoltaic power generation systems corresponding to each power flow radiation line is counted; and combined with the power flow disorder and the three-phase imbalance, a comprehensive evaluation is carried out on each power flow radiation line belonging to the trunk line to obtain the key sections of the power grid in the distribution area and to actively integrate and manage the power grid in the distribution area.

[0012] In one embodiment, determining the power flow increment includes:

[0013] Calculate the power difference between each power grid line in the shortest reachable path and its preceding power grid line, where the power flow increment is the sum of all positive power differences in the shortest reachable path.

[0014] In one embodiment, determining the power flow coordination coefficient includes:

[0015] The output power of each photovoltaic power generation system at all times during peak power generation is formed into a first sequence, and the power of each power grid line at all times during peak power generation of the photovoltaic power generation system is formed into a second sequence. The metric distance between the first sequence and the second sequence is calculated, and the power flow coordination coefficient is negatively correlated with the metric distance.

[0016] In one embodiment, obtaining the power flow radiation lines of each photovoltaic power generation system includes:

[0017] The number of lines in the shortest reachable path between each photovoltaic power generation system and each power grid line, the power flow increment, and the power flow coordination coefficient are normalized to form a first evaluation vector; based on the first evaluation vector, a comprehensive evaluation algorithm is used to obtain the first comprehensive score of each photovoltaic power generation system and each power grid line.

[0018] A threshold segmentation is performed on all the first comprehensive scores of each photovoltaic power generation system, and the power grid lines with the first comprehensive score greater than the segmentation threshold are regarded as the power flow radiation lines of the photovoltaic power generation system.

[0019] In one embodiment, determining the power flow change includes:

[0020] Calculate the power difference of each power grid line in the local neighborhood of each power flow radiation line at adjacent times, and calculate the sum of the power differences of all power grid lines in the local neighborhood of each power flow radiation line. The power flow change is the cumulative result of all the sums in the local neighborhood of each power flow radiation line over a preset number of times.

[0021] In one embodiment, determining the current turbulence includes:

[0022] The average number of power grid lines within the local neighborhood of each tidal flow radiation line at the preset number of time intervals is calculated and determined as the tidal flow reversal amount of each tidal flow radiation line. The tidal flow disorder is obtained by combining the tidal flow reversal amount with the tidal flow change amount.

[0023] In one embodiment, the tidal current disorder is the product of the tidal current reversal amount and the tidal current change amount.

[0024] In one embodiment, determining the three-phase imbalance includes:

[0025] The three-phase voltage imbalance is calculated based on the three-phase voltage at each time point, and the three-phase imbalance is the average of all the three-phase voltage imbalances over the preset number of time points.

[0026] In one embodiment, obtaining the key cross-section of the power grid in the distribution area includes:

[0027] The second evaluation vector is composed of the tidal current disorder of each tidal current radiation line belonging to the trunk line, the number of photovoltaic power generation systems corresponding to each tidal current radiation line belonging to the trunk line, and the three-phase imbalance of each tidal current radiation line belonging to the trunk line. The second comprehensive score of each tidal current radiation line belonging to the trunk line is obtained by using a comprehensive evaluation algorithm.

[0028] The second comprehensive score of all power flow radiation lines belonging to the trunk line is divided into threshold segments, and the power flow radiation lines with the second comprehensive score greater than the segmentation threshold are regarded as key sections of the power grid in the distribution area.

[0029] In one embodiment, the proactive integrated governance of the power grid in the distribution area includes:

[0030] By connecting parallel capacitor banks and phase-switching switches at key sections of the power grid in the distribution area, and obtaining the control strategies of the parallel capacitor banks and phase-switching switches, proactive integrated management of the power grid in the distribution area can be carried out.

[0031] This application has at least the following beneficial effects:

[0032] This application first uses a power grid dynamic monitoring module to obtain the power flow distribution map of the distribution area power grid at various times based on the topology map of the distribution area power grid, and collects the three-phase voltage of the lines in the distribution area power grid at various times, as well as the output power of each photovoltaic power generation system at various times. Then, in the power flow calculation module, based on the power flow distribution map at the peak power generation time of the photovoltaic power generation system, it obtains the shortest reachable path from each photovoltaic power generation system to each power grid line; it analyzes the power change between adjacent power grid lines in the shortest reachable path to determine the power flow increment from each photovoltaic power generation system to each power grid line; the power flow increment is used to quantify the power flow decrease phenomenon between the photovoltaic power generation system and the power grid line, improving the accuracy and reliability of determining the power flow radiation line of the photovoltaic power generation system; it analyzes the difference between the output power of each photovoltaic power generation system during the peak power generation period and the power of each power grid line at the same time to determine the power flow coordination coefficient between each photovoltaic power generation system and each power grid line; combining the number of lines in the shortest reachable path, the power flow increment, and the power flow coordination coefficient, it comprehensively evaluates each power grid line to obtain the power flow radiation line of each photovoltaic power generation system; this solves the problem of not being able to analyze the power flow radiation line of the photovoltaic power generation system. Effective identification of problems improves the accuracy of subsequent key section identification; Distribution grid integration and governance module: By analyzing the power changes of each power grid line within its local neighborhood at adjacent times, the power flow variation of each power flow radiation line is determined. Combined with the number of power grid lines experiencing power flow reversal at adjacent times within the local neighborhood of each power flow radiation line, the power flow disorder of each power flow radiation line is obtained. Power flow disorder can effectively assess the impact of photovoltaic power generation on the grid, especially when the photovoltaic system is large-scale or has many access points. By identifying areas of power flow disorder, reasonable access points and access methods can be provided for photovoltaic power generation, thereby avoiding local overload or voltage fluctuation problems and ensuring that the photovoltaic power generation system can maximize grid-connected power generation without affecting grid safety. Based on the deviation between the three-phase voltages at different times in each power flow radiation line, the three-phase imbalance of each power flow radiation line is determined. The number of photovoltaic power generation systems corresponding to each power flow radiation line is counted. Combined with the power flow disorder and the three-phase imbalance, a comprehensive evaluation of each power flow radiation line belonging to the trunk line is conducted to obtain key sections of the distribution grid and proactively integrate and govern the distribution grid. This application selects power flow radiation lines with high power flow disorder and severe three-phase imbalance as key sections, bringing the distribution network governance as close as possible to the user side. It regulates the sources of three-phase imbalance and disordered power flow distribution, comprehensively improving the proactive control capability of the distribution network's power quality. It identifies key sections that restrict the power flow distribution and three-phase imbalance governance of high-proportion distribution network areas, adaptively determines the location of proactive integrated governance of the distribution network, and can effectively reduce the three-phase voltage imbalance and power flow problems caused by high-proportion photovoltaic access, improve the power quality of the distribution network, reduce line losses, and enhance the safety, stability, and power supply quality of the distribution network. Attached Figure Description

[0033] 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.

[0034] Figure 1 A block diagram of an active integrated governance system for distribution grids with high photovoltaic integration, provided in this application;

[0035] Figure 2 This is a schematic diagram of the equivalent circuit of the power grid in the transformer substation.

[0036] Figure 3 This is a functional flowchart of the power flow calculation module;

[0037] Figure 4 This is a functional flowchart of the integrated governance module for the power grid in the distribution area. Detailed Implementation

[0038] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the active integration and governance system for distribution grids with high photovoltaic grid integration 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.

[0039] 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.

[0040] The following description, in conjunction with the accompanying drawings, details the specific scheme of the active integration and governance system for transformer substations with high photovoltaic grid access provided in this application.

[0041] This application provides an embodiment of an active integration and governance system for a distribution grid with a high proportion of photovoltaic (PV) grid integration. Specifically, the following block diagram of the active integration and governance system for a distribution grid with a high proportion of PV grid integration is provided. Please refer to [link / reference]. Figure 1 The system includes: a power grid dynamic monitoring module, a power flow calculation module, and a distribution area power grid integrated management module.

[0042] The power grid dynamic monitoring module is used to obtain the power flow distribution map of the power grid at various times based on the topology map of the power grid in the distribution area, collect the three-phase voltage of the lines in the power grid at various times, and the output power of each photovoltaic power generation system at various times.

[0043] The power supply range of a distribution network is relatively wide, and the equipment is sparsely distributed, with numerous points and a wide area. Photovoltaic power generation is generally achieved through inverters to connect the distribution network to the grid. This embodiment utilizes a distribution network topology identification tool to effectively identify and classify different connection methods in the power grid, obtaining the topology diagram of the distribution network. A distribution network with a high proportion of photovoltaic access transforms the original radial passive network into an active network. The equivalent circuit diagram of the distribution network is shown below. Figure 2 As shown, the power flow in the distribution area is complex, which increases the difficulty of controlling and managing the distribution system.

[0044] in, Figure 2 middle The resistance of the transformer substation line. For the transformer area line reactor, L represents the voltage of the substation in the distribution area, L represents the load in the distribution area, and DG represents the photovoltaic power source in the distribution area. For the active power of the load, For the reactive power of the load, The active power output of the photovoltaic power source. The reactive power output of the photovoltaic power source. This refers to the voltage at the point of common coupling (PCC) of the transformer substation.

[0045] Resistance in the power grid lines of the transformer substation Much greater than reactance According to the paper (Chen Qian, Feng Yuan, Li Cheng, et al. Real-valued power flow algorithm for new energy transformer substations oriented towards edge computing [J]. Electric Drive, 2025, 55(01):61-69.DOI:10.19457 / j.1001-2095.dqcd25634.), this embodiment simplifies the AC variables from vector sums to scalar sums, and the impedance angle... The impedance angle is very small and can be ignored. This leads to reactance With resistance There is a 90° phase difference between them, and the reactance It is very small; similarly, the impedance angle can be ignored. There exists a situation where a 90° phase difference exists between reactive power Q and active power P, and the reactive power Q is very small. Then, in this embodiment, the complex impedance... and complex power To convert to real numbers, specifically:

[0046] ;

[0047] ;

[0048] in, To convert the complex impedance to a real number, To convert complex power to real numbers, P represents the real part of the complex power, i.e., active power, and Q represents the imaginary part of the complex power, i.e., reactive power. This embodiment uses the same processing method based on the node transformation strategy and power flow algorithm disclosed in the paper "Real Power Flow Algorithm for New Energy Distribution Areas Oriented to Edge Computing" to obtain the power flow distribution map of the distribution area's power grid topology. In this embodiment, the power flow distribution map is collected every 30 minutes, and the power of each power grid line in the power flow distribution map is converted to real numbers using the aforementioned real-number conversion method. The implementation user can set the power flow distribution map collection time interval according to actual conditions; this embodiment does not impose any restrictions.

[0049] It should be noted that the power data collected and analyzed in this embodiment are all real-valued power data.

[0050] The distribution network in the transformer substation adopts a three-phase four-wire main line and a single-phase meter box distribution structure for branch lines. Lines containing three phase wires and one neutral wire are designated as main lines, while lines containing only one phase wire and one neutral wire are designated as branch lines. Traditional transformer substations install metering and data acquisition devices at the power supply point, focusing only on the three-phase imbalance at that point. This approach cannot accurately perceive the overall operating status of the transformer substation, resulting in a problem of overall grid balance but extreme imbalance along the main lines. Therefore, this embodiment deploys metering and data acquisition devices on the transformer substation lines to acquire the phase voltage of each phase and the output power data of each photovoltaic power generation system. The acquisition time interval for both phase voltage and output power data is 30 minutes, which can be set by the implementer and is not limited in this embodiment.

[0051] The power flow calculation module (1) obtains the shortest reachable path from each photovoltaic power generation system to each power grid line based on the power flow distribution map of the peak power generation time of the photovoltaic power generation system; analyzes the power change between adjacent power grid lines in the shortest reachable path, and determines the power flow increment from each photovoltaic power generation system to each power grid line.

[0052] During peak periods of photovoltaic (PV) power generation, the more abundant the voltage support provided by the PV system, the wider the range of its power flow radiation influence. Peak PV power generation typically occurs between noon and afternoon; therefore, this embodiment selects 12:00 noon as the peak power generation time of the PV system and 9:00 to 15:00 as the peak power generation period.

[0053] During peak periods, the output power of photovoltaic (PV) power generation cannot be fully consumed by local loads. Excess power is transmitted radially along the power grid lines, leading to increased power and altered flow direction on nearby grid lines, thus affecting the power flow distribution of the distribution area's grid lines. This embodiment obtains a power flow distribution map of the distribution area's grid at peak power generation times. The more output power from the PV system flows into the grid lines, the greater the power flow on the grid lines, and the more profound the influence of the PV system's power flow on the lines. Therefore, this embodiment identifies the power flow radiation lines of the PV system based on the grid lines in the distribution area affected by the PV system's power flow radiation.

[0054] In this embodiment, the negative of the absolute power value of the power grid line is used as the edge weight of the directed edge in the power flow distribution diagram. Taking the power flow distribution diagram of the power grid in the transformer area at the peak power generation time as an example, the power grid line connected to the photovoltaic power generation system a is taken as the source point. Along the power flow direction of the power grid line, the path selection algorithm is used to obtain the shortest reachable path from the photovoltaic power generation system a to each power grid line. When the shortest reachable path is empty, it means that the power flow from the photovoltaic power generation system to the power grid line is unreachable. The path selection algorithm in this embodiment adopts Dijkstra's algorithm. Dijkstra's algorithm is a well-known existing technology. Implementers can choose other feasible path selection algorithms according to the actual situation. This embodiment does not impose any restrictions.

[0055] Due to the high penetration rate of photovoltaic (PV) power systems in the power grid of the distribution area, the later power lines in the shortest reachable path may not be within the power flow radiation range of PV system a, making it impossible to effectively identify the power flow radiation line of PV system a. The power flow between the PV system and the power flow radiation line shows a decreasing trend. The earlier power lines in the shortest reachable path are more likely to be the power flow radiation line of PV system a. Furthermore, due to the power inflow from PV system a, the power flow of the power grid lines is more coordinated with the output power of the PV system.

[0056] Based on the above analysis, this embodiment obtains the shortest reachable paths from photovoltaic power generation system a to each grid line, counts the number of grid lines within the shortest reachable paths, and calculates the power difference between each grid line within the shortest reachable path and its preceding grid line. The sum of all positive power differences is calculated as the power flow increment from photovoltaic power generation system a to each grid line, used to quantify the decreasing power flow phenomenon between photovoltaic power generation system a and the grid lines. The more the power flow between the photovoltaic power generation system and the grid lines conforms to the decreasing phenomenon, the smaller the power flow increment value.

[0057] (2) Analyze the difference between the output power of each photovoltaic power generation system during peak power generation and the power of each power grid line during the same period, and determine the power flow coordination coefficient between each photovoltaic power generation system and each power grid line; combine the number of lines in the shortest reachable path, the power flow increment, and the power flow coordination coefficient to comprehensively evaluate each power grid line and obtain the power flow radiation line of each photovoltaic power generation system.

[0058] During the peak power generation period of photovoltaic power generation system a, the output power of photovoltaic power generation system a at all times is arranged into a first sequence according to the time sequence. Taking grid line x in the distribution area power grid as an example, during the peak power generation period, the power of grid line x at all times is obtained and arranged into a second sequence according to the time sequence. The power flow coordination coefficient between photovoltaic power generation system a and grid line x is then calculated. Specifically:

[0059] In the formula, It is the first sequence of photovoltaic power generation system a during peak power generation. It is a function of the dtw (Dynamic Time Warping) algorithm. This represents the second sequence of power grid line x during peak power generation. To ensure that the value is greater than 0 and to avoid a denominator of 0, this embodiment... The implementer can set it according to the actual situation, and this embodiment does not impose any restrictions.

[0060] It should be understood that this embodiment only provides a method for calculating the distance between the first sequence and the second sequence. Implementers can choose other feasible distance measurement algorithms. The higher the similarity between the first sequence and the second sequence, the more significant the synergistic characteristics between the power flow of the grid line x and the output power of the photovoltaic power generation system a, and the more likely the power flow of the grid line x is the power inflow of the photovoltaic power generation system a.

[0061] This embodiment normalizes the number of lines in the shortest reachable path from photovoltaic (PV) system a to each grid line, the power flow increment from PV system a to each grid line, and the power flow coordination coefficient between PV system a and each grid line. The normalized results form the first evaluation vector for PV system a and each grid line. It's important to note that when there is a power flow unreachable condition from the PV system to a certain grid line, the first evaluation vector takes the value [1, 1, 0]. This first evaluation vector from PV system a to each grid line is used as input to the comprehensive evaluation algorithm. The number of lines in the shortest reachable path and the power flow increment are minimal indicators; the smaller the value, the higher the final evaluation score. The power flow coordination coefficient is a large indicator; the larger the value, the higher the final evaluation score. The output is the first comprehensive score from PV system a to each grid line, reflecting the power flow influence of PV system a on each grid line in a high-proportion PV grid connection scenario.

[0062] The greater the influence of a photovoltaic (PV) power generation system on the power flow of the grid lines, the more power the PV system injects into the grid lines, and the higher the likelihood that the grid lines will act as power flow radiation lines. Therefore, in this embodiment, the first comprehensive score of the PV system a to each grid line is used as the input of the Otsu method, and the first segmentation threshold is output. Grid lines with a first comprehensive score greater than the first segmentation threshold are designated as power flow radiation lines of the PV system a.

[0063] At this point, power flow radiation zoning processing has been performed on all power grid lines in the distribution area. It should be noted that a power grid line can simultaneously serve as a power flow radiation line for multiple photovoltaic power generation systems. In this embodiment, the normalization processing uses the Sigmoid function. The comprehensive evaluation algorithm and Otsu's method are both existing well-known technologies, and their specific processes will not be elaborated upon. The functional flowchart of the power flow calculation module is as follows: Figure 3 As shown.

[0064] The integrated management module of the power grid in the distribution area (1) determines the power flow change of each power grid line by the power change of each power grid line in the local neighborhood of each power flow radiation line at adjacent times, and obtains the power flow disorder of each power flow radiation line by combining the number of power grid lines that have power flow reversal in the local neighborhood of each power flow radiation line at adjacent times.

[0065] Critical sections refer to specific cross sections or nodes in a power grid that have a critical impact on the operation and stability of the power system. They play a vital role in power system planning, three-phase imbalance management, and power flow regulation. In distribution grids with a high proportion of photovoltaic (PV) integration, selecting power flow radiation lines with high power flow disorder and severe three-phase imbalance as critical sections, and placing them as close as possible to the user side, can fully leverage the proactive integration and management effects of the power grid. This allows for regulation targeting the sources of three-phase imbalance and disordered power flow distribution, reducing line losses, and improving the operational stability of the distribution grid.

[0066] Because photovoltaic output is affected by weather uncertainties, photovoltaic power generation systems in distribution grids have strong randomness and volatility. Photovoltaic access transforms traditional distribution grids from passive to active networks, causing changes in the values ​​and directions of active and reactive power on distribution lines, resulting in a dynamic evolution of power flow distribution in distribution grids and exacerbating the power flow changes on distribution grid lines.

[0067] In this embodiment, in the power grid topology diagram of a high-proportion photovoltaic (PV) grid access area, a graph search algorithm is used to obtain the shortest path between any two grid lines, and the number of grid lines passing through the shortest path is calculated as the topological distance between the two grid lines. This embodiment uses each power flow radial line as the center and obtains all nodes and lines within the topological neighborhood scale with a topological distance smaller than the topological neighborhood scale, as the power flow distribution sub-graph of each power flow radial line. The purpose of setting the topological neighborhood scale is to extract the local neighborhood power flow information of the power grid along the power flow radial line. Therefore, provided this condition is met, the size of the topological neighborhood scale can be set by the implementer. In this embodiment, the topological neighborhood scale is set to 5. Based on this, this embodiment calculates the power flow variation of each power flow radial line. The specific calculation method is as follows:

[0068] In the formula, Let y be the change in tidal current along the tidal current radiation line. These are the power values ​​of power grid line m at time t and time t+1 in the power flow distribution sub-graph of the power flow radiation line y, respectively, where T is the length of a preset number of time points. In this embodiment, T=48. Let y be the total number of power grid lines in the power flow distribution subplot of the power flow radiation line y.

[0069] It should be understood that the greater the difference in power flow of the power flow lines within the power flow distribution sub-map, the higher the degree of change in the power flow distribution of the power flow radiation lines. The power flow change is used to reflect the dynamic evolution of the power flow distribution of the power flow radiation lines.

[0070] In a distribution network, power flow reversal can exacerbate the complexity of power quality management and lead to stability issues. Taking a power flow radial line y as an example, in the power flow distribution sub-diagram of power flow radial line y, this embodiment counts the number of power flow reversals occurring from time t to time t+1, which is taken as the reversal value at time t. The average of the reversal values ​​from time t=1 to time t=T-1 is calculated as the power flow reversal amount of power flow radial line y.

[0071] This embodiment calculates the power flow disorder of a power flow radiation line y by multiplying its power flow change and power flow reversal. The power flow change reflects the dynamic evolution of power flow distribution along the radiation line within the power grid. The purpose of calculating the power flow reversal is to assign greater weight to power flow radiation lines with frequent power flow reversals, thus preventing overload or even damage to power grid lines or equipment due to changes in power receiving direction. A higher power flow disorder indicates a greater need for power grid regulation within the distribution area, and a greater likelihood that the power flow radiation line will be selected as a critical section.

[0072] (2) Determine the three-phase imbalance of each power flow radiation line based on the degree of deviation between the three-phase voltages at each time in each power flow radiation line; count the number of photovoltaic power generation systems corresponding to each power flow radiation line; combine the power flow disorder and the three-phase imbalance to conduct a comprehensive evaluation of each power flow radiation line belonging to the trunk line, obtain the key sections of the power grid in the distribution area, and actively integrate and manage the power grid in the distribution area.

[0073] A single power grid line can simultaneously serve as a power flow radiation line for multiple photovoltaic power generation systems. Through power electronic equipment, grid regulation can be implemented to comprehensively control the three-phase imbalance and disordered power flow distribution caused by multiple photovoltaic power generation systems. In this embodiment, the number of photovoltaic power generation systems corresponding to each power flow radiation line is counted as the multi-photovoltaic access coupling degree of each power flow radiation line.

[0074] The asymmetry of load distribution, the differences in the temporal and spatial characteristics of load consumption, and the high proportion of single-phase photovoltaic power integration in the distribution network are the main reasons for the significantly exacerbated three-phase imbalance in the distribution network, posing a great challenge to the power supply reliability and security of the distribution network. The distribution network adopts a distribution structure of three-phase four-wire main line and single-phase meter box on branch lines. Therefore, the power flow radiation lines belonging to the main line are more suitable as key sections for grid regulation.

[0075] This embodiment obtains the three-phase voltage of each power flow radiation line. And calculate the average phase voltage value. Using the three-phase voltage imbalance defined in "IEEE Std. 112-1991" The calculation method is expressed as follows: In the formula, max{} is the maximum value function. In this embodiment, the mean value of the three-phase voltage imbalance of each power flow radiation line from t=1 to t=T-1 is calculated as the three-phase imbalance of each power flow radiation line.

[0076] Based on the above steps, this embodiment obtains the power flow disorder, multi-photovoltaic access coupling degree, and three-phase imbalance degree of each power flow radial line belonging to the trunk line. These are sequentially combined into a vector as input to the comprehensive evaluation algorithm. The power flow disorder, multi-photovoltaic access coupling degree, and three-phase imbalance degree are all extremely large indicators; that is, the larger the value, the higher the final evaluation score. The output is the second comprehensive score of each power flow radial line belonging to the trunk line, which serves as the integrated governance value of each power flow radial line belonging to the trunk line. The integrated governance value reflects the value of proactive integrated governance of power grid lines, thereby identifying key sections that constrain the power flow distribution and three-phase imbalance governance of high-proportion transformer areas. Power grid lines with high integrated governance value should be treated as key sections for power quality governance.

[0077] The second comprehensive score of all power flow radiating lines belonging to the trunk line is used as the input of the Otsu method, and the second segmentation threshold is output. Power flow radiating lines with a second comprehensive score greater than the second segmentation threshold are designated as key sections of the distribution network. Parallel capacitor banks and phase-changing switches are connected to the key sections of the distribution network. The functional flowchart of the distribution network integrated management module is as follows: Figure 4 As shown.

[0078] This method acquires the active and reactive power of all nodes in the distribution network, the active power of photovoltaic devices, and the node voltage amplitude. A set of five-tuples is set as the coordinates for model construction, and a Markov decision model is built. A deep neural network (DQN) is used to fit the function, resulting in control strategies for parallel capacitor banks and commutator switches. This achieves proactive integrated management of the distribution network, effectively reducing three-phase voltage imbalance and power flow problems caused by high-proportion photovoltaic integration, improving power quality, reducing line losses, and enhancing the safety, stability, and power supply quality of the distribution network. Specifically, a multi-timescale control method is used to collaboratively train and construct the upper-level agent of the Markov decision model. The five-tuples consist of the upper-level agent's state space, action space, reward function, state transition probability function, and discount factor.

[0079] It should be noted that the control strategy for obtaining the parallel capacitor bank and the commutation switch is a well-known existing technology, and will not be described in detail in this embodiment.

[0080] 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, specific embodiments of this specification have been described above. 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.

[0081] The various embodiments in this specification 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.

[0082] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A district network active fusion management system applied to high proportion photovoltaic access, characterized in that, The system comprises: A power grid dynamic monitoring module: used for obtaining the power flow distribution diagram of each time of the transformer area power grid based on the topological structure diagram of the transformer area power grid, collecting the three-phase voltage of each time of the line of the transformer area power grid, and collecting the output power of each photovoltaic power generation system at each time; A power flow calculation module: used for obtaining the shortest reachable path of each photovoltaic power generation system to each power grid line based on the power flow distribution diagram of the peak power generation time of the photovoltaic power generation system; analyzing the power change between adjacent power grid lines in the shortest reachable path to determine the power flow power increment of each photovoltaic power generation system to each power grid line; Analyzing the difference between the output power of each photovoltaic power generation system at the power generation peak period and the power of each power grid line at the same period to determine the power flow coordination coefficient of each photovoltaic power generation system and each power grid line; combining the number of lines in the shortest reachable path, the power flow power increment, and the power flow coordination coefficient to comprehensively evaluate each power grid line and obtain the power flow radiation line of each photovoltaic power generation system; A transformer area power grid fusion management module: used for determining the power flow change of each power flow radiation line by the power change of each power grid line in the local neighborhood of each power flow radiation line at adjacent times, combining the number of power grid lines in the local neighborhood of each power flow radiation line that have power flow reversal at adjacent times to obtain the power flow confusion degree of each power flow radiation line; According to the deviation degree between the three-phase voltages of each power flow radiation line at each time, the three-phase imbalance degree of each power flow radiation line is determined; the number of photovoltaic power generation systems corresponding to each power flow radiation line is counted, and the power flow confusion degree and the three-phase imbalance degree are combined to comprehensively evaluate each power flow radiation line that belongs to the trunk line, obtain the key section of the transformer area power grid, and actively manage the fusion of the transformer area power grid; The determination of the power flow change includes: Calculating the power difference of each power grid line in the local neighborhood of each power flow radiation line at adjacent times, calculating the sum of the power differences of all power grid lines in the local neighborhood of each power flow radiation line, and the power flow change is the cumulative result of all the sum values in the local neighborhood of each power flow radiation line in the preset number of times; The determination of the power flow confusion degree includes: Calculating the average value of the number of power grid lines that have power flow reversal in the local neighborhood of each power flow radiation line in the preset number of times to determine the power flow reversal amount of each power flow radiation line, and the power flow confusion degree is the product of the power flow reversal amount and the power flow change.

2. The active fusion management system for high proportion photovoltaic access district network of claim 1, wherein, The determination of the power flow power increment includes: Calculating the power difference between each power grid line and its previous power grid line in the shortest reachable path, and the power flow power increment is the cumulative sum of all positive power differences in the shortest reachable path. 3.The district network active fusion management system applied to high proportion photovoltaic access of claim 1, wherein, The determination of the power flow coordination coefficient includes: The output power of each photovoltaic power generation system at the power generation peak period is arranged into a first sequence, and the power of each power grid line at all times during the power generation peak period of the photovoltaic power generation system is arranged into a second sequence, the metric distance between the first sequence and the second sequence is calculated, and the power flow coordination coefficient is negatively correlated with the metric distance.

4. The application of the district network active fusion management system for high proportion photovoltaic access according to claim 1, characterized in that, The power flow radiation line of each photovoltaic power generation system is obtained, including: The number of lines in the shortest reachable path, the power flow increment, and the power flow synergy coefficient of each photovoltaic power generation system and each power grid line are normalized to form a first evaluation vector; based on the first evaluation vector, a comprehensive evaluation algorithm is used to obtain a first comprehensive score of each photovoltaic power generation system and each power grid line; All the first comprehensive scores of each photovoltaic power generation system are threshold segmented, and the power grid lines with a first comprehensive score greater than a segmentation threshold are regarded as power flow radiation lines of the photovoltaic power generation system.

5. The active fusion management system for high proportion photovoltaic access of the district network according to claim 1, wherein, The determination of the three-phase imbalance degree comprises: The three-phase voltage imbalance degree at each moment is calculated based on the three-phase voltage at each moment, and the three-phase imbalance degree is the average of all the three-phase voltage imbalance degrees in the preset number of moments.

6. The active fusion management system for high proportion photovoltaic access of the district power grid of claim 1, wherein, The acquisition of the key section of the substation area power grid comprises: The power flow confusion degree of each power flow radiation line belonging to the trunk line, the number of corresponding photovoltaic power generation systems of each power flow radiation line belonging to the trunk line, and the three-phase imbalance degree of each power flow radiation line belonging to the trunk line are combined to form a second evaluation vector, and a comprehensive evaluation algorithm is used to obtain a second comprehensive score of each power flow radiation line belonging to the trunk line; The second comprehensive scores of all the power flow radiation lines belonging to the trunk line are threshold segmented, and the power flow radiation line with a second comprehensive score greater than a segmentation threshold is regarded as a key section of the substation area power grid.

7. The application of the district network grid active fusion management system for high proportion photovoltaic access according to claim 1, characterized in that, The active fusion management of the substation area power grid comprises: Parallel capacitor banks and phase-changing switches are connected to the key section of the substation area power grid, the control strategy of the parallel capacitor banks and the phase-changing switches is obtained, and the active fusion management of the substation area power grid is performed.

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