The Design And Application Of High Voltage Shunt Capacitor Device For Monitoring Its State

With rapid development of the national economy, the scale of power grid and its capacity is increasing year by year, causing the structure and power distribution of power system having changed significantly. The reactive power compensation plays an particularly improtant role in ultra high voltage system. Reactive power compensation device especially capacitor compensation applications is not only directly related to the merits of the quality of power system supply, but also directly affects the safety and economy of power system.Due to the shortage of shunt capacitor running state monitoring device can not be applied to the analysis of existing 35 kV and above voltage capacitor group, the meticulous research on the fault characteristics and harmonic characteristic of 35 kV capacitor in 500 kV substation was presented firstly. On this basic, analyzing various factors of capacitor group which casuse it break and calculating the current changes of various fault conditions to sum up the law. The mehod of fault judgement and measurement of capacitor group was presented. Then the model of shunt capacitor bank monitoring was established to simulate the current and voltage changes under various fault conditions. Analysis and comparison of the results between laboratory tests and the theory was done to lay the foundation for on-site installation and commissioning.Based on the above theory, a high voltage shunt capacitor device for monitoring its state was designed and developed. The device can achieve real-time monitoring the running state of the whole group and single capacitor, and has potential isolation and good communication ability, can find the reasons for failure and fault of capacitor. Besides,it can do maintenance and operation of the capacitor with purpose, plan, target, and improve the electric device and power system reliability.A group of 35 kV capacitor in a 500 kV substation was selected as the application object to install the high voltage shunt capacitor group graded insulation state-monitoring device. Analysis and comparison between simulation test results and operation results were done to test the similarities and differences in laboratory and field operation for providing the basis to further improve the monitoring system, finding out the capacitor failure at the same time and puting forward the improvement measures to improve the stability of the system.