Research On Distributed On - Line Monitoring Technology For Intelligent Substation Capacitive Equipment

The intelligentialize of substation is one of the important developing direction of smart grids the number of high-voltage capacitor-type accounts for approximately40%to50%of the total number of substation device, and the probability to be fault is higher, the monitoring of its insulation condition is of great significance in promoting the intelligentialize of substation. Currently, the capacitive device monitoring methods can be divided into two kinds:off-line and on-line mode. The off-line test can measure the relatively accurate dielectric loss and capacitance of device under ideal conditions, but can’t monitor the variation of device insulation state in real-time. Thus, insulation on-line monitoring technology of power device gradually developed on the basis of off-line preventive tests. This paper makes a in-depth research to the key technology of intelligent substation capacitive device distributed on-line monitoring based on problems from the development, on-site installation and data analysis during the latter time of capacitive device distributed on-line monitoring equipment in a110kV substation in Yunnan province. Firstly, a in-depth analysis is made to the research status of capacitive device online monitoring and problems existed. Secondly, a comparative analysis is made among online and offline measurement in terms of measuring principle, method and environment. Note that there is essentially different between online and offline measurement, and both of them have their own advantages. Then, a comparative analysis is made among distributed and centralized measurement used by online monitoring, pointing out the advantages of distributed measurement. Simultaneously, the key technique of distributed implementations is analyzed, such as wireless communication technology, time synchronization programs based on wireless, and absolute and relative method of dielectric loss measurement. Next, explore the equipment on-site installation, proposed engineering measures to reduce errors of leakage current, dielectric loss and capacitance. Finally, against the differences between measurement data in scene and theoretical value, collect leakage current waveform both upon normal operation and off-line preventive test to analyze it, do a measurement to the leakage current sensor used by equipment, and make a relevant evaluation to measured data from multiple dimensions.