Distinguish between partial discharge and external interference signal for GIS on-line monitoring
Jing Yang · Dianli zidonghua shebei · 2007
The electromagnetic wave excitated by partial discharge inside GIS(Gas-Insulated Switch-gear) and external corona-generated interference are analyzed using the wavelet transform in time-frequency-domain.The feasibility of distinguishing between internal discharge and exte rnal interference is discussed.When only single signal exists,the frequency of corona-generated interference in substation is commonly under 130 MHz with less than 70 MHz bandwidth.However,the bandwidth of whatever electro-magnetic wave excited by partial discharge inside GIS is at least double times of that of corona-generated interference.When both signals exist,they can be synthetically distinguished by band-width and advancing front.The result shows that the method is easy and effective,meeting the requirements of signal distinguish for on-line monitoring.