Research and design of distributed online monitoring system for power capacitor in substation based on WiFi wireless communication

During the operation of power capacitor, leakage, expansion and other abnormal phenomena may occur due to overvoltage, tide, thermal degradation and harmonic overload. Failure to monitor the performance and state of power capacitors in time may lead to power accidents, which will affect the safe operation of power system. Therefore, the monitoring method of performance of power capacitor was studied in this paper. Firstly, the defects and shortcomings of the existing monitoring methods were pointed out based on the analysis of the characteristics of power capacitors. Then the dielectric loss tangent was selected as the characteristic parameter to measure the performance, and the detection principle was proposed. After that, the distributed on-line monitoring system based on WiFi wireless communication was designed against the operating environment of power capacitors in substation, which included the overall scheme, the local signal detection terminal taking DSP as the main control unit and the centralized human-computer interaction designed in LabVIEW. Finally, the design system was tested. The results show that the measurement error of characteristic parameter is less than 10%, and the accuracy of state discrimination is 100%, so the design system have advanced technique and functionality. In addition, higher monitoring efficiency can be achieved because the performance of multiple power capacitors can be monitored at the same time by the distributed monitoring. Therefore, the system has high practical and popularization value.