Comparison study of partial discharge detection methods for switchgears

Metal enclosed switchgears are widely used in distribution networks. According to the investigation, most of power outages are caused by switchgears thermal or partial discharge failure directly. So, more attentions are focused on the detection of switchgear cabinets. For the partial discharge detection, there are many PD detection methods can be used for switchgears, such as acoustic emission (AE), ultrahigh frequency (UHF), transient earth voltage (TEV), high-frequency current, et al. However, the comparative analysis of the sensitivity and locating effect of the above methods is not enough. In this paper, a real switchgear partial discharge test platform with three cabinets was set up, partial discharges from three kind of typical models in different locations of the switchgear under various voltages were measured by the four methods, and the sensitivity of detection and locating for the four methods were compared. The test results show that the AE method has the best sensitivity on the switchgear PD detection, TEV method has largest amplitude of PD signal; the four methods can locate the partial discharge all. The union of AE and TEV is the most effective measure to detect the PD of switchgears in the on-site detection environment with a high background noise.