Leakage Current Detection for Surge Arrester in Switchgear Based on Time-Frequency Analysis Method

Abstract

[Introduction] In the power system, the surge arrester in switchgear plays an important role in suppressing transient overvoltage and discharging large pulse currents, which is of great significance to maintain its normal and stable operation. [Method] A time-frequency analysis method based on the autocorrelation coefficient and the Chi-squared test optimization was proposed in the research to effectively suppress the noise interference on leakage current signal detection. Firstly, the measurement results of the current sensor and the shunt were analyzed. Then, the wavelet transform based on the autocorrelation coefficient and the Chi-squared test optimization was used to eliminate the noise interference in the signal in order to determine the optimal decomposition size to better suit the occasion of small signal-noise ratio. [Result] Based on the analysis in the software platform, it is concluded that the optimized wavelet algorithm denoising has stronger anti-interference capability and better waveform quality on the basis of measurement of the shunt. Finally, an online leakage current detection device is developed to verify the leakage current detection model proposed in the research. [Conclusion] The experimental results show that the device can realize the real-time detection of leakage current of the surge arresters.

Keywords

• leakage current detection
• noise interference
• optimized wavelet
• time-frequency analysis method
• anti-interference capability