Study On A Novel Real-time Optimum Control System Of Neutral Grounding Impedance For Distribution Systems

It’s difficult to solve the problems of high neutral displacement voltage,large grounding fault current and high arc grounding overvoltage by using single kind of neutral grounding mode.So,a novel real-time optimum control system of neutral grounding impedance based on IGBT is proposed in this paper.Based on the existing technology of IGBT grounding arc-suppression control system research, the principle of novel neutral grounding impedance real-time optimum control system is presented.When the operation of distribution system is normal,the IGBT is cutoff, the arc-suppression coil L is not put into operation.When the grounding fault occurs,the switch-on and switch-off of IGBT can be controlled by PWM,the grounding impedance can be adjusted continuously, and then the grounding fault current can be compensated efficiently. Two kinds of novel real-time optimum control methods of neutral grounding impedance for distribution systems is proposed in the paper:based on passive IGBT and based on active IGBT; the PWM control strategy and the technique data of real-time optimum control technology are presented; the theory is analyzed in detail,the control circuit is designed,and the ATP simulation of 35KV power system is carried out.The desired results are obtained.The simulation results show that the novel neutral grounding impedance real-time optimum control system is with inductance continue regulating,excellent dynamic responding,high control precision and the residual fault current approaching to zero, accelerating grounding fault arc self-extinguishing,preventing neutral displacement overvoltage.The proposed novel control system will improve the level of distribution automation, and enhance power quality and power supply safety, has a broad prospect of application.