The Study On DCPD Pattern Recognition Of Large Capacity Storage Capacitors

The High Voltage Storage Capacitor (HVSC), which is the kernel of impulse power, has small volume and large capacity. Its insulation capability determines the service reliability of impulse power system. Nowadays, only capacitance, insulation resistance, leakage current, dielectric loss or discharge times are counted as characteristics of capacitors. These parameters, a) can't find out the failure inside when it comes out of manufacturer; b) can't evaluate the capacitors when they're in service. Recently, Partial Discharge (PD), which is widely used as a preventative test method in much electric power equipment, is considered that it should be useful in capacitor. But, almost all the PD tests are based on power frequency and low capacitance sample, whose sensitivity, analysis methods etc. are not suitable for HVSC.This thesis works on the DC PD detection system which is designed for HVSC specially. It started off PD mechanism, analyzed the noise and tested the parameters of capacitors. Then, a high sensitivity and noise rejection DC PD detection system was designed. Through the DC PD test of various capacitors, test criterions of different measurement periods, including transient and stable period, were established. At last, based on the different statistic parameters, such as the magnitude of discharge and the wave shape, preliminary recognition of defect types was realized.All the work the thesis introduced can be used in HVSC factory detection and in service performance check, and it's useful for manufacturer to improve their craft or check their equipments. At the same time, it's also the basic of further PD research on the patterns how discharge developed.