Development Of TSC/TCR Combination Petersen Coil Controller

When single-phase ground fault occurs, it is easy to form arc on the earthing point. Neutral earthing via Petersen coil system is an effective solution to extinguish arc in single-phase earthing fault. It makes great sense to improve power supply reliability and keep safe operation. In this paper, TSC/TCR combination Petersen coil was proposed based on TSC Petersen coil. The hardware and software of controller were designed.Firstly, the working principle and structure of Petersen coil were analyzed. Through the establishment of equivalent circuit and mathematical model, parameters were determined. 3-point method of capacitance current measure- ment and the criterion of single-phase ground fault were analyzed.In the hardware circuit design of Petersen coil controller, Seatech sx-340 was selected as the main board, ZhongTai PM511P as data acquisition card. TSC trigger circuit was designed, including the zero-crossing detection circuit and thyristor trigger circuit. And contactor was combined with the thyristor switch used in TSC. Then a software system was designed. Controller's operating system was DOS6.22 with Turbo 2.0 compiling environment. C lan- guage was used to program the procedures of controller interface, time and parameter setting, fault recording and auto-tracking compensation, etc. In the auto-tracking compensation procedure, the three-point measurement was to track capacitive current. The instantaneous value of neutral point voltage was to judge the grounding fault quickly. Look-up table method was used to determine the required capacitance groups and thyristor trigger angle.The prototype experiment in the static simulation system of 10 kV distri- bution network verified the advantage of this Petersen coil controller.