The Research Of Capacitance Current Automatic Measuring And Tuning Method Based On The Approach Of Signal Injection

The neutral resonant grounding by arc-suppression coils is widely utilized in intermediate voltage distribution network in our country. In order to improve the compensatory precision, the grounding capacitance of the network should be exactly measured. However, the existing detection methods, which mainly adopt indirect approaches, have the characteristics of low detective precision, complex detection processes and weak anti-disturbances ability. Moreover, frequent operations on electric apparatus will do harm to the safety of the network. Nowadays, the signal injection approaches for capacitance current measurement prevail, otherwise, the approaches with injection signal of conversed frequency, working frequency have limitations in their concepts.To solve the above-mentioned problems, this paper analyzes the principles of resonant grounding network, and discusses the capacitance current detection methods in use all over the world, then presents the improved method based on special frequency signal injection approach. With such method, the currents are injected from the secondary windings of PT to the distribution network, and the voltages of the second windings are measured. Then, by the simultaneous equations, the grounding capacitance can be calculated. This method adopts the vector to calculate, in order to reduce the times of injection signals. Compared with other approaches, this method has a more precise model;it can effectively measure the capacitance currents without adjusting the apparatus in the network. Moreover, it can be easily realized by computer controlling. This method enjoys the features of safety, quickness and exactness.At last, the Simulink and SimPowerSystems of MATLAB emulator are utilized, in order to build up the model of compensation network. The simulation results are used to prove the feasibility and the validity of such method in capacitance current detection.The realization of the method is also discussed in this paper. 80C196KC singlechip is used in the hardware design. The procedure of capacitance current measurement and auto-tuning is programmed. The above studies can lay the foundation for the realization of auto-compensation equipments.This subject is meaningful to perfect the measurement of capacitance current in...