Development Of New Arc-Suppression And Over-Voltage Protection Device

Distribution network of 6~35kV of China operates mainly on the mode of neutral point non-effectively grounding, which include neutral non-grounded and resonant grounded. The signal phase-to-earth fault happens most frequently in the neutral non-effectively grounded system. Especially, the signal-phase arc grounding has been threatening the safe operation of our distribution network. This paper mainly studies the effective method to solve single-phase grounding fault, especially to solve single-phase arc grounding.The current arc-suppression devices are mainly automatic tuning arc-suppression coil and grounding phase quick-ground device. But these two types of arc-suppression devices are all flawed. In this paper, the merits and demerits of present arc-suppression devices are analyzed; a new arc-suppression device coordinately used grounding phase quick-ground device and arc-suppression coil is proposed; the overall construction of this arc suppression device are designed. Besides, analyzing the merits and demerits of present system capacitance current measurement methods and ground fault line selection methods, and considering the structure and working characteristics of new arc-suppression and over-voltage protection device, this paper proposes the right tuning program. The paper also discusses the working flow of this device when single-phase grounding fault occurs.Analyzing the generation mechanism and fault characteristics of major faults in the medium-voltage distribution network, this paper proposes the comprehensive determination method of faults in the distribution network, which provides a premise for the arc-suppression device to determine and dealing with the fault when it happens. According to the functional requirements of this device, a monitoring and control unit based on dsPIC digital signal controller (DSC) is designed. And its hardware and software implementations are elaborated. The software procedures are written by the MPLAB C30 C compiler.This paper simulates the working flow of the device by Matlab/Simulink to verify the feasibility of the device work and the method to measure system-to-ground capacitance current.Although this device adds the cost of arc-suppression work in a certain extent, it could compensate earth current and extinguish arc quickly, and enabled the problem of signal-phase ground arcing faults to obtain a good solution. For the occasions which have huge arc harms and require highly in arc-suppression effect, it is a good choice.