Three Frequency Method Of Capacitive Current Of Power Grid Measurement And The Research Of The Compensation Arc Suppression Device

With the increase of the power distribution network capacity, the requirements for power safety are also increasing. In the fault types of power system, the three-phase short-circuit is the most serious fault, while the single-phase short-circuit is the most frequent fault. Generally speaking,In order to solve the single-phase grounding fault,We use the arc suppression coil. There will be distributed capacitance in the power line,which will makes the capacitance current. Inductive current of arc suppression coil can offset the capacitance current, Achieve the purpose of arc suppression.However, the arc suppression coil is also has problems, it has Large volume and weight, and it response very slowly. We replace the traditional arc suppression coil with the active arc suppression device. The arc suppression device can realize the precise compensation of the electric current in the electric network, And it response very fast.In order to compensate for the capacitive current of the system, Capacitance current measurements must be carried out in the normal condition of the system. In capacitance current measurement technology, Signal injection method is to inject Different frequency current in PT, Establish the equations to solve the system to the ground capacitance value by establishing the equation set. But this method is affected by leakage resistance and leakage inductance. The error of the measurement and the range of the measurement is small.Aiming at the problem of the measurement of capacitive current, this paper proposed an improving method, that is Neutral point injection three frequency method. The paper analysed the measuring principle and made the simulation, then verified the feasibility and accuracy of the method. The simulation and experiment results show that, the improved measuring method is easy to operate, the measure precision is high, and no impact to power grid.It can make the measurement of capacitive current of power distribution network more accurate and convenient.This paper projected a active power compensator based on PWM technology. This device constituted by system busbar, active inverter and control system, providing a hardware platform for the research of full compensation arc suppression coil. The experimental data show that, all active compensation arc suppression device carried out an effective compensation of single phase ground fault capacitive current,verified the feasibility of active full compensation control scheme.