Research On The Characteristic Of Electromagnetic Interferences And The Standardized Test For PD Monitoring In Substation

Electromagetic interference is a most important cause for wrong alarming and failing to alarm of on-line PD detection in substation,and also a key bottleneck for the development of on-line PD detection.The characteristics,sources and influence factors of electromagnetic interference s were studied and the methods of interference simulating and grading also standardized testing scheme were proposed through analyzing the technology of anti-interference on domestic and foreign PD detection.The work is as follow:Typical substations and test points were selected,and UHF and high frequency current PD detection method were used to systematically study the characteristics of electromagnetic interference signal in substation and the location of the interference signal sources was performed.The mobile communication signa ls and the external discharge of HV equipments in substation are the main forms of electromagnetic interferences for PD detection.The amplitude of original signals is above 200 mV and the frequency bands are in UHF detection;the amplitude of the interference signals in the method of high frequency current is in the range of 5.8 to 501 mV,and the spectrum distribution is generally below 90MHz;the switch cabinets in more than 50% of substations exisit the pulse signals.The relationship between dynamic change of electromagnetic interference signals and meteorological conditions(temperature,humidity)and load was studied by the method of data association analysis,the influence of geographical position and voltage level on the dynamic change of electromagnetic interference s was studied by means of comparison.The results show a dominant influence factor on the characteristics of electromagnetic interference signals is temperature,especially the discharge interferences,the correlation degree is above 0.9,the humidit y is the second and the load is the smallest.Geographical position and voltage level can affect the type and amplitude of electromagnetic interference signa l,and the probability of occurrence of signal.According to the source,type,intensity and frequency of electromagnetic interference signals,the simulation scheme and standaried classification of typical electromagnetic interference signa ls and the scheme of standardized interference test platform of PD monitoring devices were exploration to carry out which referenced standard classification method of EMC,combined with the working characteristics and the influence degree of PD monitoring devices,and the corresponding evaluation indexes are given.