Research On Controller Of Arc-Suppression Coil Based On Programmable Logic Controller

Neutral grounded system though arc-suppression coil (also be known as resonance grounding system) are being used more and more widely in China recently. Arc is easy to be extinguished due to current in arc-suppression coil compensate grid-to-ground capacitive current which greatly improve continuity and reliability of power supply. The rapid and accurate compensation function depends on development of control technology, so it is significant to make depth research in arc-suppression coil controller in order to achieve rapid and accurate control of arc-suppression coil.A variety of resonant grounding system and arc-suppression coil controller were introduced in this paper, also three main part of resonance grounding system:capacitance current measurement technology, auto-tuning control method and single-phase to ground fault line selection were described in detail. At last, the developmental programm based on PLC was selected. Then fault line selection model in resonant grounding system was built by SIMLINK toolbox in MATLAB to find the characteristics of the fault line and provide a theoretical basis for the choice of the fault line selection.Functions of capacitance current measurement, appropriate operating point setting, manual shift regulating and fault alarm of arc-suppression coil were achieved by PLC; functions of zero sequence current collection, single-phase to ground fault line selection and liquid crystal display were achieved by embedded system in the development of arc-suppression coil controller; they complement each other to achieve a rapid flexible control of arc-suppression coil. Main control program and each functional module subprogram of PLC and embedded control system were compiled according to control requirements. In order to achieve these function successfully, neutral point displacement voltage collection circuit, zero sequence current collection circuit and32-5line priority coding circuit were designed.The controller is the combination of PLC and embedded system, arc extinguishment and fault line selection, software programming and hardware design. After repeated modification and debugging, trinity functions of capacitance current measurement arc extinguishment and fault line selection are achieved. And it has high practical value.