Development Of A System In Partial Discharge Signals Detector Based On Virtual Instrument

XLPE cables have been used in HV power network more and more extensively. The safeoperation of the power grid is closely related with the insulation state of the power cable.Partial Discharge is one of the main causes for insulation failure of power cables. And it’s theimportant indicator to reflect the cable insulation condition. Partial Discharge signal detectioncan show potential failure of power cables and guarantee safety and reliable operation of thepower system. Therefore, how to detect the Partial Discharge signal that is great significanceto carry out the safety work of power grid.This paper analyzes the characteristics of the Partial Discharge signal and methods ofPartial Discharge signal detection. As the traditional Partial Discharge detector can’t meet thedemand of field test, this paper proposes a solution of using the oscillating wave and virtualinstrument technology on Partial Discharge signal detection, and a technical solution forvirtual instrument system which is used on Partial Discharge signal acquisition.This paper designs the structures of the Partial Discharge signal detection system, anddetermines the hardware design of the system. It includes the design of oscillating waveoccurred circuit, circuit design of the Partial Discharge signals measuring, calibrator circuitdesign and system anti-interference design. Partial Discharge signals measuring circuit uses aNI-DAQ act as data acquisition unit, and determinates the parameters of data acquisitiondevice.Then this paper designs the software part of the system. The whole software is developedon the base of C++platform. It mainly includes sampling and saving of signals, handling ofPartial Discharge signals. And it can locate the failure position. Two key software modules areintroduced in this paper: calibration test and Partial Discharge test control. Parts of sourcecode are introduced in this paper and show some representative software operation interfaces.In the end, the paper presents the detection and evaluation results of cables withinsulation failure. The results show that the system can operate well and the Partial Dischargesignals which are captured by the system have good signal characteristic, so it can beeffectively used to evaluate and locate insulation failure.