Study On Rapid Identification And Inhibition Of Arc Grounding Over-voltage

With the rapid development of the national economy, stricter requirements to security and stability of power system operation and power quality are proposed by the society. In power system, over-voltage is an important factor affecting safe operation of power grid. Arc over-voltage, as one type of the most common internal over-voltage of distribution network, is a tremendous threat to the security and stability of power system due to its long duration.The establishment of over-voltage real-time monitoring and analysis systems is the basis of over-voltage suppression. The paper analyzes the over-voltage waveforms measured from HG-ZXJ91 series over-voltage online monitoring system. It also researches and analyzes the development mechanism of arc grounding over-voltage theoretically. Based on these, a method which can identify arc grounding over-voltage quickly and accurately after analyzing a large number of simulation waveform is proposed. Meanwhile, an improved operation is presented against existing methods'disadvantages: keeping neutral point separated when system is under routine operation, then measuring grid-to-ground capacitance current regularly. if it changes, the arc suppression coil should be tunned immediately. Once arc grounding over-voltage signals from over-voltage classification system is received, operation mode should be changed to resonant grounding mode; after program judges the grounding fault is eliminated, make the coil quit and the neural point grounded quickly.Based on arc suppression coil self-loss conductance and line-to-ground conductance, the power grid-to-ground capacitive current and arc suppression coil tuning parameters is calculated. By sampling the voltage and current on the neutral point during normal operation, calculating the system-to-ground capacitance in real-time and finding the value of arc suppression coil compensation inductance, the conditions for real-time arc suppression coil tuning are provided. This method can calculate the capacitive current with a residual current less than 0.5 A, and the compensation is more precise than the conventional method.