Line fault identification method using pole line fault voltage curve clusters to perform principal component clustering analysis

Abstract

The invention relates to a line fault identification method using pole line fault voltage curve clusters to perform principal component clustering analysis and belongs to the power system relay protection technical field. According to the method, single-pole grounding faults are set along a line from near to far; external faults are set as rectifying-side outlet faults, rectifying-side alternating-current system faults, inversion-side outlet faults and inversion-side alternating-current system faults; under a 10kHz sampling rate, pole line fault voltage curve clusters under internal faults in the range of the whole line and under the external faults of the line are acquired respectively through simulation; data of pole line fault voltage curve clusters within 1ms are selected so as to be subjected to principal component clustering analysis; a two-dimensional PCA space formed by a principal component PC1 and a principal component PC2 is selected; two kinds of clustering point clusters which reflect the line faults and the external faults can be formed on the PCA space; when a fault occurs, in-window pole line fault voltage data are mapped to the two-dimensional PCA space when test data are at 1ms; and Euclidean distance is adopted to measure the distances between the test data and the two kinds of clustering points clusters, and the distances between the test data and the two kinds of clustering points clusters can form fault identification criteria.

Description

technical field [0001] The invention relates to a line fault identification method for performing principal component cluster analysis by utilizing pole line fault voltage curve clusters, and belongs to the technical field of electric power system relay protection. Background technique [0002] At present, the DC transmission line protection that has been put into operation in my country is mainly based on the so-called traveling wave protection, differential undervoltage protection, longitudinal differential protection and low voltage protection based on the change rate and change amount. Among them, traveling wave protection and differential undervoltage protection are the main protections, and the action protection speed is fast, but they are easily affected by interference such as harmonics, lightning strikes, and sampling value jitter, and their ability to withstand transition resistance is relatively poor. The reason why it is susceptible to interference such as harmon...

AI Technical Summary

Problems solved by technology

Among them, traveling wave protection and differential undervoltage protection are the main protections, and the action protection speed is fast, but they are easily affected by interference such as harmonics, lightning strikes, and sampling value jitter, and the ability to withstand transition resistance is relatively poor

The reason why it is susceptible to interference such as harmonics, lightning strikes, and sampling value jitter is because the robustness of the protection algorithm is poor; the traveling wave protection with the voltage change rate du / dt as the core criterion often cannot detect the remote high-impedance fault of the UHVDC line , the fundamental reason is that with the increase of transition resistance and fault distance, du / dt decreases, and it is impossible to effectively distinguish the internal high-impedance grounding fault and the external fault of the line within the stretching time

The longitudinal differential protection and low-voltage protection are used as backup protection, and the action time is longer [4-8]

As a high-impedance fault detection, the longitudinal differential protection relies on time delay to avoid the transient response during the AC system fault to ensure that it does not malfunction. At the same time, in order to avoid malfunction during power adjustment, SIMENS differential protection design The blocking logic is added, so the exit delay of the longitudinal differential protection is too long. On the one hand, the longitudinal differential protection may often fail to function as a backup protection. On the other hand, the protection of the DC control system may act first. Cause unnecessary DC blocking accidents

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