Development Of Arc-suppression And Over-voltage Protection Device

Ineffectively grounded systems of 7.2-35kV neutral point are widely used in power distribution network in china, namely the neutral non-grounded system, the neutral grounded system via resistance and the neutral grounded system via arc suppression coil, and the single phase-to-earth fault happens most frequently in this network. Arc grounding is a serious trouble threatening the safe operation of power distribution network. Arc suppression coil grounding or resistance grounding functions as protection, it can eliminate the power-frequency arc. During a single phase to ground fault caused by an intermittent arc, both the over-voltage on the healthy phase and the arcing current flowing through the faulty position are of high frequency properties. Arc suppression coil cannot compensate and the arc is difficult to extinguish by it, but certain shortcomings still exist.Firstly, this paper introduces the neutral point connection mode of power system, analyzes the fundamental principle and its function characteristics of the three modes. Furthermore, a simulated model of neutral non-grounded system is established in this paper, sets line parameters and simulink package of Matlab, analyzes the metal grounding fault and arc grounding fault, these process are simulated by Matlab, and presents the simulation results and the waveform, and set metal grounding and arc grounding fault criterion.A new type method is put forward, which can eliminate arcing grounding over-voltage. The method is that the neutral grounding method based on metal grounding and dividing current technique, which makes residual current at fault point low to nearly zero, slow down the muzzle velocity of voltage restoring and restrict its maximum to avoid arc restriking as well as simulated by Matlab, proved it feasible.The paper analyses the line selection ago and compare with these method, put forward to adopt line selection module to select fault line in order that making arc-suppression device and line selection protection reliable cooperation. This paper describes briefly the structure and working principle of the arc extinguishing and over-voltage protection device and gives detailed presentation to the features. The paper analyzed its design idea, and hardware composition, and described its software and anti-interference design.Lastly, a 380V experiment model was built up with which some propositions are proved by experiment in this paper.