Power distribution network high-resistance fault identification method based on wavelet packet energy ratio

Abstract

The invention discloses a power distribution network high-resistance fault identification method based on a wavelet packet energy ratio. The method comprises the following steps: 1, obtaining a voltage signal of a monitoring point of a power distribution network, and extracting a zero-sequence voltage signal of the monitoring point; 2, performing frequency domain analysis on the zero-sequence voltage of the monitoring point by using a wavelet packet decomposition method, and performing energy extraction on nodes; 3, calculating a high-frequency-band energy proportion Eh_% and a low-frequency-band energy proportion El_% of the zero-sequence voltage; and 4, calculating the ratio of the low-frequency-band energy E1 to the high-frequency-band energy Eh of the zero-sequence voltage, and takingthe ratio as an identification characteristic quantity of the high-resistance fault, i.e., comparing the zero-sequence voltage wavelet packet energy ratio with the zero-sequence voltage wavelet packetenergy ratio in a normal operation state so as to judge whether the power distribution network has the single-phase high-resistance fault or not. According to the method, the high-resistance fault and the normal state can be effectively identified.

Description

technical field [0001] The invention belongs to the technical field of distribution network fault identification, and in particular relates to a method for identifying high-resistance faults in a distribution network based on wavelet packet energy ratios. Background technique [0002] The difficulty in the study of high-resistance faults in distribution networks lies in the extraction of high-resistance fault features. In the case of high-resistance faults, the fault current is weak, the three-phase voltage and current are almost the same as before the fault, the steady-state characteristics are not obvious, and the detection difficulty increases. [0003] At present, the research on feature extraction of high-resistance faults is mainly carried out through steady state method and transient state method. In the steady-state method, the high-resistance ground fault judgment method based on the difference between the neutral point current and the zero-sequence current project...

AI Technical Summary

Problems solved by technology

[0004] In the transient signal analysis method, the fault location method is partially based on the analysis and processing of the transient zero-sequence current signal, although it is not affected by the fault location, fault angle and fault resistance, but the start-up criterion needs to set a threshold; using HHT (Hilber As the fault resistance increases, the identification method of extracting transient information of zero-sequence voltage decreases; the current method based on wavelet analysis to extract transient characteristics of high-resistance faults is effective, but it lacks the consideration of normal conditions such as load fluctuations A comparative study on the impact of the proposed method on the identification results

[0005] In general, the current research on high-resistance fault feature extraction lacks stable fault feature quantities that are not related to factors such as fault resistance, and lacks research on the influence of other operating states on feature quantities

Images