A direction finding method for partial discharge in air-insulated substation based on UHF array

Summary

Partial discharge (PD) is a symptom of incipient faults in high-voltage (HV) equipment, and provides useful information for insulation diagnosis. Generally, online PD monitoring instruments are assembled on high-cost apparatuses such as transformers. However, in the air-insulated substation (AIS), it may be too expensive and inefficient to install PD monitoring instruments for every equipment such as current/voltage transformer, circuit breaker and lightning arrester. Therefore, a movable platform with ultra-high-frequency (UHF) antenna array has been tried to apply for PD localization in AIS. Nevertheless, the size of present antenna array is so large that it is not convenient for onsite detection. In this paper, a direction finding method for PD is proposed for reducing the array size and improving the directional accuracy. The detected signal from antenna array is converted to several frequency points by using discrete Fourier transform (DFT). Then the signal subspace transformation (SST) algorithm is used to focus wideband PD signal to narrowband signal. Finally the multiple signal classification method (MUSIC) algorithm is applied to estimate the direction-of-arrival (DOA). The uniform rectangle array (URA) is employed to estimate both elevation and azimuth of PD source, and the directional accuracy for different array size is investigated with numerical simulations. The directional error is less than 3° in the simulated low signal to noise ratio (SNR) condition, and it indicates that this direction finding method has a good anti-jamming performance. Experimental results show that the directional error is less than 4.2º, which proves the feasibility of this direction finding method applied in AIS.

Additional informations

Authors

M-X. ZHU, Y-B. WANG, J-B. DENG, Y. Li, H-B. MU, G-J. ZHANG, H. Li

Keywords

Partial discharge, air-insulated substation, ultra-high frequency, phased array, direction finding