High Frequency Partial Discharge Detection Research Articles

Partial Discharge Pulse Segmentation Approach of Converter Transformers Based on Higher Order Cumulant

As one of the most effective methods to detect the partial discharge (PD) of transformers, high frequency PD detection has been widely used. However, this method also has a bottleneck problem; the biggest problem is the mixed pulse interference under the fixed length sampling. Therefore, this paper focuses on the study of a new pulse segmentation technology, which can separate the partial discharge pulse from the sampling signal containing impulse noise so as to suppress the interference of pulse noise. Based on the characteristics of the high-order-cumulant variation at the rising edge of the pulse signal, a method for judging the starting and ending time of the pulse based on the high-order-cumulant is designed, which can accurately extract the partial discharge pulse from the original data. Simulation results show that the location accuracy of the proposed method can reach 94.67% without stationary noise. The field test shows that the extraction rate of the PD analog signal can reach 79% after applying the segmentation method, which has a great improvement compared with a very low location accuracy rate of 1.65% before using the proposed method.

Case Analysis on the Abnormal Heating Defect of a 220kv XLPE Cable Intermediate Joint

In this paper, through the infrared temperature measurement and high frequency partial discharge detection, we found an abnormal heating defect in the intermediate joint of 220kV cable. After dissecting the intermediate joint and measure the insulation resistance of internal epoxy components in the laboratory, the causes of the defects were analyzed. The overall heating of the middle joint of the cable shall be caused by the damp insulation. Partial discharge detection can not detect the cable insulation moisture defects. The effect of The infrared temperature measurement is good. After that, the hidden danger of the equipment was dealt with in time and a serious power grid accident is avoided. This case verifies the practicability of infrared temperature measurement in abnormal heating diagnosis of the cable line, and also verifies the limitations of partial discharge detection for internal damp fault diagnosis. This paper also points out the design defect of intermediate joint of similar structure, which provides the basis and reference for the future work.

Defect simulation and state characteristic analysis of cable joints with tip defects

In recent years, the breakdown of the body and accessories of high voltage cables has increased gradually. Taking the tip defect of 110 kV high voltage cable joint as an example to carry out electric field simulation analysis, the distribution and change law of electric field under this defect are put forward. Based on full working condition detection platform of high voltage cable, the simulation test of the defect is carried out. The effectiveness of various charged detection methods and on-line monitoring methods has been studied, and the variation rules of cable state under different working conditions have been obtained. The results show that, when tip defect is between stress cone silicon rubber and main insulation of cable body, electric field distortion around the tip shows discharge, and the breakdown potential is 83 kV. The high frequency partial discharge detection method and ultrasonic partial discharge detection method can detect the defects effectively, among which anti-interference ability of high frequency partial discharge detection at the capacitive arm is the best, and detection sensitivity of the grounding current is higher in the on-line monitoring. The thermal efficiency of load current has little effect on development of tip defects. But with the increase of test voltage, the high frequency emission volume increases obviously and breakdown occurs easily at higher voltage.

Analysis and Treatment of the Cause of Heating of Single-core XLPE Cable GIS Terminal

In this paper, the heat generation of 110kV cable GIS terminal discovered by infrared thermal imager is briefly described. The causes of heat generation are discussed by means of sheath current detection and circulation calculation, and further analysed by high frequency partial discharge monitoring system, timely handling of equipment hidden dangers, to avoid the occurrence of vicious accidents. Through the analysis and judgment of this accident, the significance of infrared temperature measurement, sheath current detection technology and high frequency partial discharge detection technology for the discovery of cable defects is proved, which provides a basis and reference for future work.