CN-121546520-B - Intelligent checking and early warning method for global feeder protection fixed value of power distribution network

CN121546520BCN 121546520 BCN121546520 BCN 121546520BCN-121546520-B

Abstract

The invention discloses a method for intelligently checking and early warning global feeder protection fixed values of a power distribution network, which belongs to the technical field of relay protection of power systems and comprises the steps of collecting relevant data of the power distribution network, carrying out positive sequence component calculation, establishing a davidian equivalent circuit model, carrying out iterative optimization of parameters, calculating action current based on the davidian parameters, checking the level difference of the fixed values of adjacent feeder lines in real time, generating a set value list, and sending the set value list to a protection device, wherein the relevant data of the power distribution network comprises current and voltage, calculating the instantaneous increment of the current, carrying out 3-layer decomposition by using Daubechies4 wavelet, extracting high-frequency detail coefficients d1-d3, carrying out fault pre-judgment, and carrying out Stockwell transformation and Hilbert transformation analysis on the current data based on fault judgment results. The invention can greatly improve the reaction speed and the processing capacity of the power grid under the emergency, and ensure the safety and the stability of the operation of the power grid.

Inventors

SHI HENGCHU
YANG WANGXIA
ZHANG MIN
LI XIULAN
YOU HAO
CHEN XIAOFAN
SHI ZEBING
LI YINYIN
HU XIAO
DING XIAOLI
SHEN YANG
YAN NINGXIA

Assignees

云南电网有限责任公司

Dates

Publication Date: 20260505
Application Date: 20260116

Claims (5)

1. The method for intelligently checking and early warning the global feeder protection constant value of the power distribution network is characterized by comprising the following steps of, Collecting power distribution network related data, carrying out positive sequence component calculation, establishing a davidian equivalent circuit model, carrying out iterative optimization of parameters, calculating action current based on the davidian equivalent circuit parameters, checking the level difference of the fixed values of adjacent feeder lines in real time, generating a closed value list, and transmitting the closed value list to a protection device; Calculating the current instantaneous increment, performing 3-layer decomposition by using Daubechies4 wavelets, extracting a first-layer detail coefficient d1, a second-layer detail coefficient d2 and a third-layer detail coefficient d3, performing fault pre-judgment, performing Stockwell transformation and Hilbert transformation analysis on current data based on a fault judgment result, calculating a mixed fault index based on an analysis result, performing multi-level fault pre-warning and generating corresponding measures; Aggregating parameters of the equivalent circuit of the whole network Dai Weining, generating a fault thermodynamic diagram and a fixed value conflict report, calculating the optimal fixed value combination of the whole network based on a game theory model, and transmitting an optimal fixed value to an edge node through a GOOSE message; The steps of establishing the davidian equivalent circuit model and performing iterative optimization of parameters include: calculating Dai Weining an equivalent voltage using the positive sequence voltage data, calculating Dai Weining an equivalent impedance from the current and voltage variations; Calculating an initial Dai Weining equivalent voltage and an initial Dai Weining equivalent impedance by using a three-point method; Global optimization is carried out on Dai Weining equivalent voltages and davitin equivalent impedance by using a particle swarm optimization algorithm, and an optimal initial solution is found; Based on optimization of a particle swarm optimization algorithm, carrying out local optimization by using a Gaussian-Newton iteration method, calculating residual errors and a jacobian matrix by using initial parameters obtained by optimization of the particle swarm optimization algorithm, and reflecting partial derivatives of the residual errors on the parameters; Updating Dai Weining parameters of equivalent voltage and equivalent impedance of davitin by using a Gaussian-Newton iterative optimization formula; Setting a convergence threshold, and updating Dai Weining equivalent voltage and davitin equivalent impedance each time until the residual error is smaller than a preset convergence threshold to obtain optimized Dai Weining equivalent voltage and davitin equivalent impedance parameters; the method for calculating the action current based on the davitin equivalent circuit parameters, checking the level difference of the adjacent feeder line constant values in real time, generating a closed value list and transmitting to a protection device comprises the following steps: Calculating the action current in the power grid based on the optimized Dai Weining equivalent voltage and Dai Weining equivalent impedance, and calculating the fixed value range between two adjacent feeder lines according to the action current of the adjacent feeder lines in the power grid; Setting a level difference threshold, if the fixed value range exceeds the level difference threshold, indicating that the fixed value setting of the adjacent feeder line protection is unreasonable, causing misoperation or error protection, marking the subarea of the adjacent feeder line in the power grid as a fixed value conflict subarea, generating alarm information, and reminding an operator to adjust; If the fixed value range does not exceed the level difference threshold, passing fixed value check, and keeping the protection fixed value unchanged; If the fixed value range is equal to the level difference threshold, judging as a critical state, adding a sub-region where adjacent feeder lines in the power grid are positioned into a fixed value optimization task list, and executing fixed value optimization in the next fixed value setting period; generating a complete constant value list based on the obtained action current and a constant value verification result; And using a GOOSE message protocol to send the fixed value list to each protection device.
2. The method for intelligently checking and early warning global feeder protection fixed values of a power distribution network according to claim 1, wherein the method is characterized in that the method for calculating current instantaneous increment and performing 3-layer decomposition by using Daubechies4 wavelets, extracting a first-layer detail coefficient d1, a second-layer detail coefficient d2 and a third-layer detail coefficient d3 for fault pre-judgment comprises the following steps: collecting current data of a current feeder line in real time, preprocessing, calculating a difference value between a current value at the current moment and a current value at the previous moment, obtaining a current instantaneous increment, setting a current instantaneous increment threshold, and performing three-layer decomposition on a current signal of which the instantaneous increment exceeds the current instantaneous increment threshold by using Daubechies4 wavelet transformation; The wavelet decomposition process decomposes the signal into an approximate coefficient and a detail coefficient, a first layer detail coefficient d1, a second layer detail coefficient d2 and a third layer detail coefficient d3 are obtained after three layers of wavelet decomposition are completed, energy calculation is carried out on each layer of detail coefficient, and high-frequency fluctuation in the current signal is analyzed; And performing frequency domain conversion on the detail coefficient of each layer by using Fourier transformation, setting a high-frequency fluctuation threshold, screening out high-frequency fluctuation higher than the high-frequency fluctuation threshold, combining the instantaneous increment of the current with the energy characteristic, and judging that the power grid fails if the instantaneous increment of the current and the energy change of the detail coefficient exceed the set threshold at the same time.
3. The method for intelligently checking and early warning the global feeder protection constant value of the power distribution network according to claim 2, wherein the method for performing Stockwell transformation and Hilbert transformation analysis on the current data based on the fault judgment result, calculating a hybrid fault index based on the analysis result, performing multistage fault early warning and generating corresponding measures comprises the following steps: Denoising the current signal judged as the power grid fault by using wavelet transformation, and capturing short-time frequency characteristics in the current signal by using Stockwell transformation to obtain frequency components corresponding to each moment; Finding out extreme points of the signals, constructing an upper envelope line and a lower envelope line by using a three-time Hermite interpolation method, calculating the average value of the upper envelope line and the lower envelope line, removing the envelope obtained by the average value calculation from the original signals to obtain a first IMF component, removing the extracted first IMF component from the original signals to obtain residual signals, and continuously extracting the IMF components of the residual signals until all IMF components are decomposed; calculating to obtain the resolution of the signal in the frequency domain by analyzing the frequency spectrum width and the time domain width of the signal; Calculating a hybrid fault index of the power grid based on an amplitude spectrum obtained by Stockwell conversion, an instantaneous frequency obtained by Hilbert conversion and a frequency resolution; Setting a high-risk threshold and a medium threshold, wherein the high-risk threshold is larger than the medium threshold, if the mixed fault index is larger than or equal to the high-risk threshold, the high-risk alarm is triggered, fault equipment is automatically isolated, a protection fixed value is adjusted, if the mixed fault index is smaller than the high-risk threshold and larger than or equal to the medium threshold, the medium fault hidden danger is indicated to the power grid, an operator is prompted to pay attention to monitoring the state of the power grid, if the mixed fault index is smaller than the medium threshold, the normal operation of the power grid is indicated, and the power grid is continuously monitored.
4. The method for intelligently checking and early warning the global feeder protection constant value of the power distribution network is characterized in that the method comprises the steps of aggregating all-network davidian equivalent circuit parameters, generating a fault thermodynamic diagram and a constant value conflict report, collecting data from all davidian equivalent circuit parameters and mixed fault index records of the feeder, storing all aggregated data in a cloud platform, generating a fault thermodynamic diagram by using a data visualization technology, classifying regions according to mixed fault indexes according to low, medium and high risk levels, and marking by the depth of the same color; And based on the aggregated data, checking the constant value conflict existing in the power grid, and automatically generating a constant value conflict report.
5. The method for intelligently checking and early warning global feeder protection constant values of a power distribution network according to claim 4, wherein the method is characterized in that a game theory model-based calculation of the optimal constant value combination of the whole network is performed, and a GOOSE message is used for sending the optimal constant value to an edge node to divide the power distribution network into a plurality of subareas based on the overall structure of the power distribution network, and feeder and protection devices in each subarea are modeled; Optimizing the protection constant value of each subarea by using a non-cooperative game model, wherein the protection device of each subarea is regarded as a game participant, and the protection device selects the protection constant value according to the running state of the subarea and an objective function and obtains the optimal combination by solving Nash equilibrium points of the game; In the game process, a gradient descent method is adopted to optimize the protection constant value of each subarea, the constant value parameters of each subarea are updated in an iterative mode, the comprehensive target of the cost and risk of each subarea is minimized, and the optimal protection constant value combination is finally obtained through multiple iterative calculation; Generating a whole network optimal fixed value configuration list based on the optimal protection fixed value combination calculated by the game theory model, and transmitting the optimal fixed value configuration list to each protection device of the power distribution network through a GOOSE message protocol; The positive sequence component calculation is to analyze three-phase current by using a positive sequence component method after current and voltage data are acquired, and calculate a positive sequence component.

Description

Intelligent checking and early warning method for global feeder protection fixed value of power distribution network Technical Field The invention relates to the technical field of relay protection of power systems, in particular to a method for intelligently checking and early warning a global feeder protection fixed value of a power distribution network. Background Conventional power distribution network protection methods typically rely on static fixed value protection schemes that set protection fixed values based on historical experience and are operated and maintained through periodic inspection and manual adjustment. However, with the continuous change of the load of the distribution network, the gradual intellectualization of the equipment and the diversification of fault types, the traditional static protection scheme shows some obvious defects. The existing power distribution network protection fixed value checking scheme is mainly used for simply judging based on fixed current and voltage data and lacks response capability to dynamic change. In addition, the interaction between feeder lines in the power grid is complex, and the traditional method cannot effectively process the factors, so that constant value conflict and error protection are easily caused, and the stability and reliability of the system are affected. Therefore, how to further improve the intelligent degree and response speed of the protection fixed value check of the power distribution network becomes the key point of the current research. Disclosure of Invention The present invention has been made in view of the above-described problems. Therefore, the invention solves the technical problem of how to further improve the intelligent degree and response speed of the protection fixed value check of the power distribution network. The method comprises the following steps of collecting power distribution network related data, carrying out positive sequence component calculation, establishing a dyvin equivalent circuit model, carrying out iterative optimization of parameters, calculating action current based on the dyvin equivalent circuit parameters, checking the level difference of adjacent feeder fixed values in real time, generating a closed value list, and sending the closed value list to a protection device, calculating current transient increment, carrying out 3-layer decomposition by using Daubechies4 wavelet, extracting a first-layer detail coefficient d1, a second-layer detail coefficient d2 and a third-layer detail coefficient d3, carrying out Stockwell transformation and Hilbert transformation analysis on the current data based on the fault judgment result, carrying out multistage fault index calculation based on the analysis result, generating corresponding measures, polymerizing the full-network dyvin equivalent circuit parameters, generating a fault thermal and fixed value conflict report, calculating the full-network optimal fixed value combination based on the game model, and sending the optimized fixed value to an edge node by GOOSE message. The optimal scheme of the method for intelligently checking and early warning the global feeder protection constant value of the power distribution network comprises the steps of establishing a dyvin equivalent circuit model and performing iterative optimization of parameters, calculating Dai Weining equivalent voltages by using positive sequence voltage data, calculating Dai Weining equivalent impedance through current and voltage changes, calculating initial Dai Weining equivalent voltages and initial dyvin equivalent impedance by using a three-point method, performing global optimization on Dai Weining equivalent voltages and dyvin equivalent impedance by using a particle swarm optimization algorithm to find an optimal initial solution, performing local optimization by using a Gauss-Newton method on the basis of PSO optimization, calculating initial parameters obtained by PSO optimization, reflecting partial derivatives of residual errors on all parameters by using a jacobian matrix, updating Dai Weining equivalent voltage and dyvin equivalent impedance parameters by using a Gauss-Newton optimization formula, setting a convergence threshold, and updating Dai Weining equivalent voltage and dyvin equivalent impedance each iteration until the residual errors are smaller than preset convergence threshold, and obtaining the optimized Dai Weining equivalent voltage and dyvin equivalent impedance parameters. The method comprises the steps of calculating action current based on the Davidin equivalent circuit parameters, checking the level difference of adjacent feeder fixed values in real time, generating a closed value list and sending the closed value list to a protection device, calculating action current in a power grid based on optimized Dai Weining equivalent voltage and Dai Weining equivalent impedance, calculating the fixed value limit between two adjacent feeders according to