Research On Cable Partial Discharge Monitoring Based Online Decision Rules

As the power cable is widely used in the power industry,the number of power cable loop put into operation has been increasing rapidly.The power cable testing technology directly related to the safe operation of the power cable,and power cable line partial discharge detection technology has been one of the hotpots.Thesis studies the problem of power cable partial discharge,proposing cable partial discharge monitoring methods and basic design.In order to test partial discharge,we must understand the principle and characteristics.So first using PSCAD to built simulation model,the simulation model can study the propagation characteristics of the signal PD by changing the cable length.For cable main insulation prone to the problem of gas defects,on-line Decision Rule-based Method about cable partial discharge is proposed,which can roughly detected PD defect location and can distinguish between single or double defect cable segment.A single 35 k V cable network model and PD source(insulating air gap)model is established,and related factors were analyzed,including PD source characteristic and location in defects section,and the number of normal segments between double defect segments,then selects the best energy characteristics of signals from different energy characteristics.Then extracts from cable joints this type of signal energy,and studies the energy distribution pattern consisting of all joints.Finally,obtains a set of decision rules used to detect and differentiate between one or two cable networks PD source.The premise of the decision rule is cable network energy distribution of all joins,through different combinations of defective segment,the characteristics of source PD,PD source location simulation study,simulation results show that the accuracy of the proposed method.This rule can judge energy distribution of all joints,directly determine the cable segment which exists PD source,and judge insulation of the cable network as a whole.In the end,the partial discharge on-line monitoring system of XLPE cable is designed.High-frequency current sensor is designed and produced,and performance of a completed sensor is tested.The passive low-pass filter is designed to filter the signal.Highly integrated RTU module and GPRS module YN4112 is utilized as a wireless remote control terminal.Through communication between GPRS and internet network,by analysis and processing the collected circulation signal which is sent tothe remote integrated information management system to determine the cable insulation condition to achieve overrun warning function,which can effectively prevent the occurrence of cable insulation accidents,improve the safe operation of for power system stability.