Partial Discharge Orientation Method in Substation Based on Ultra-High Frequency Phased Array Theory

The detection and localization of partial discharge (PD) using ultra-high frequency (UHF) sense array is applied in air-insulated substation (AIS) nowadays. However, the relevant system is of some disadvantages. For example, the volume of the sense array is so bulky, which is not convenient for on-site application. Considering phased array radar's great advantages in electronic countermeasure field, this paper researched on the feasibility and orientation accuracy of PD orientation based on phased array theory applied in AIS. The electrical equipment in AIS could be regarded as two- dimensional distribution, so uniform linear array (ULA) was used to calculate the azimuth angle. Firstly the paper explained the mathematical model of ULA and the principle of multiple signal classification (MUSIC) algorithm applied in narrow-band signal orientation. However, the PD signal is usually wide-band, causing the orientation precision decreases. So digital band pass filter was used to transform array accepted data at different frequency. Then two-sided correlation transformation (TCT) algorithm was applied to focus the wide-band UHF signal to narrow-band signal, which increased orientation precision of MUSIC algorithm. Based on theories foundation, firstly, the orientation accuracy of the method was simulated with different signal to noise ratio (SNR), the results showed that the errors of direction-of-arrival (DOA) were about 0.8°; and then the results from some experiments showed that the errors of DOA were about 2°. It indicates that this orientation method is of good accuracy and could be applied in PD orientation in AIS.