Methods And System Design Of Partial Discharge Detecting Of High-voltage Cable Accessories

The application of power cable in the power supplies is getting increased and the reliability of the supplied power is becoming more and more important for power providers and consumers. The power cable accessories is a significant part, which are connectors between cables and cables, cables and other equipments, whose fault will cause cable transmission system to collapse directly. So the operation states of the cable accessories determine the reliability of the power supplied.The cable accessory is a weak link in transmission lines,whose failure rate is very high especially in high voltage.So,it is badly necessory to detect cable accessories'fault.Partial discharge is one of the most mainly reasons which cause cable accessories breakdown, and also is closely correlated with the status of internal insulation. From the view point of on-line detection of partial discharge, the insulation properties of cable accessories were analyzed. Through the detection the internal insulation defect can be detected. If there are some potential faults in the cable accessories, an alarm signals is reported. And then some measures will be taken for the questionable cable accessories timely to ensure the security operation of the cable network. Based on the discussion of the internal insulation structure and all kinds of methods used in partial discharge on-line detection for accessories, the paper puts forward method that detecting partial discharge of cable accessories in ultra high frequency band, the method owns high SNR,which could screen most part of background noise effectively.according to the propagating features of the partial discharge signals., the partial discharge signals were coupled by UHF sensor, and then the signals were sampled by high speed data acquisition system.Several on-line detecting methods for partial discharge in high voltage cable accessories were studied in detail in this paper,including frequency response of sensors, propagation properties of PD signal, and etc.The hardware system of partial discharge detection was designed. Modularizing design method was employed which makes the design more clear. The modules of power supply, optical fiber communication, ADC, Data latched circuit, preamplifier and filter circuit etc. were designed in detail. Lastly, parts of simulation are analyzed.Finally, this paper analyses all kinds of interferences existing in high-speed circuit, including crosstalk,power noise and EMI. And then, taking some corresponding measures to the circuit, the improved PCB board was anti-interence simulated.