Correction of the Relationship between Optical-electrical Signal and Charge Quantity in Partial Discharge Combined Detection

The internal insulation defects of gas insulated electrical equipment will cause partial discharge (PD). The accurate and effective PD detection has important significance for fault assessment. Using the fluorescent fiber as the PD sensor, the PD of the four typical defects was tested. The relationship between the UHF signal and the discharge amount at different pressures, the relationship between optical signal and the discharge amount at different size defects were corrected. The results show that under different pressures, the UHF signal energy and the discharge square can always maintain a good linear relationship. For different defects, the UHF signal energy-discharge amount increases with the gas pressure. Whether there are defects of different types or different sizes of the same type, there is a good linear relationship between the integral value of the optical signal and the discharge amount. For the free metal particle defect, it is difficult to summarize the law between the particle size and the discharge amount. When the pressure in the simulated cavity is 0.3 MPa, the correction value is compared with the measured value, the relative error of the free metal particles defect is 14.4%, and the relative error of other defects is less than 5%. Taking the smallest size defect in the experiment, the calculated value of the slope k is also compared with the measured value, and the relative error obtained is less than 10%.