Design And Research On A Novel Arc-Suppression Coil Based On Magnetic Flux Controllable

With the large-scale reconstruction of city power system in recent years, the power supply network is becoming larger and larger. In addition, the enormous use of cables in city power system increases the current through the grounded capacitor. These make the single-phase fault current get greater, which lead to more and more instantaneous grounding faults unable to eliminate naturally. To solve these problems, the compensating method of neutral point grounding through Arc-Suppression Coil is commonly used in our country. After the neutral point is grounded through Arc-Suppression Coil, it can decrease the capacitor current through fault point and the over-voltage caused by the grounding fault, which is advantage for the extinguishments of electric arc.Refered to the summarization of the existing technique and method of grounding through Arc-Suppression Coil, a novel Arc-Suppression Coil is designed in terms of the principle of magnetic flux controllable. According to this theory, the reactance in the primary winding of a transformer can be controlled exactly by controlling the current of secondary winding of the transformer, which is implemented by a single phase voltage source PWM inverter. The control of the inverter's current and DC link voltage is discussed., and a control method adapt to this system is formed.A whole design idea in engineering of Arc-Suppression Coil is proposed. An apparatus, the capacity of which is up to 500kVA, is designed to industrial application in terms of the practical need in the project. The parameter choice of main circuit is dissertated. The pivotal aspects in hardware and software design have been discussed.Some problems on electromagnetic interference and cut-in action of Arc-Suppression Coil in experiments is analysed. The reasons of these problems are discussed in terms of the waveform of the experiments and the solutions are proposed.Three phase simulative experiments have been carried out on the 500kVA apparatus. Experimental results proved that the novel arc-suppression coil apparatus has the characteristic of high precision in capacitance detection, wide compensation range, fast response and few harmonics. It can be anticipated that this new arc-suppression coil have expectable future in the reformation of power network in the cities of our country.