Research On Calibration Technique Of The UHF Partial Discharge Detection System

In UHF partial discharge (PD) detection, the performance of the sensor and the detection system determines whether the insulation defects could be detected timely and effectively. However, the common principles of the calibration and evaluation on the performance of the UHF sensor and the detection system have not been established until now, both in China and abroad, which would greatly influence the utilization of this technology.This paper presents a method and platform to realize the goal of calibration of the UHF PD detection system in the laboratory and site conditions.Firstly,by using time-domain pulse referencing method under laboratory conditions, a calibration and evaluation platform of PD UHF detection is built based on the GTEM cell,in which three core quantitative characteristics are proposed:the frequency-domain equivalent height to evaluate the coupling performance of the sensor, the minimum detectable peak impulsive electric field value and the maximum saturation peak impulsive electric field value to represent the sensitivity and effective reception range of the UHF detection system. Through the comparison results between the calibration in laboratory and the simulated PD detection in a real G1S, the practical effect is well verified that the method and the test system can effectively determine the parameters of the UHF PD sensor and the detection device, and realized quantitative calibration and appropriate evaluation on them.On the basis of different types of discharge signal characteristics, the signal source which can simulate the signal of partial discharge is developed.The propagation and attenuation characteristics of the UHF signals and the injection pulse signals from typical simulated PD models in different GIS are experimentally studied in TAIKAI factory on110kV GIS and in XIKAI factory on220kV.At last, the paper puts forward the equivalent damping prediction method and equivalent pulse injection method to implement UHF detection system sensitivity verification in the field condition, which is being proved effectively by experiment.