The Control System Designed To Thyristor Switched Filter Based On CAN Bus

At present, because of the growing number of non-linear loads and the increasing of the total load in the power grid, a large number of harmonics are generated and inject into the grid, and cause the grid voltage distortion to get more and more worse. At the same time, a large number of reactive load in the power grid affects the stability of grid voltage and thr efficiency of the entire power grid severely. Therefore, the problems of the harmonic control and reactive power compensation attracts more and more attention and study, and how to consider simultaneously the harmonic control and the reactive power compensation is one of the important research topics in reactive power compensation technology. The theorem of simultaneous harmonic controlling and reactive power compensating are developing relatively rapidly, but the practical applications are still needed.This dissertation reseaches comprehensive control technology on simultaneous harmonic controlling and reactive power compensating according to the current situation of power quality in China. The dissertation firstly reviews on of harmonic and reactive power about their definition, generation, their dangers to power grid, their relationship, and current development situation, then design a thyristor switched filter control system based on CAN bus, which can switch thyristor switched capacitor (TSC) for simultaneous harmonic controlling and reactive power compensating, in order to ensure balance between supply and demand of reactive power grid, improve power quality, and reduce energy loss. This filter control system can be applied to harmonic sources of0.4KV voltage and large consumers of reactive power consumption, such as residential quarters, office buildings and large rectifier devices.The dissertation mainly describes the hardware and software design of the filter control system.In hardware design, the dissertation designs the hardware structure of the filter control system using TSC based on CAN bus, and finishes the design of its main components such as the main controller, trigger-protector, and zero-crossing switching board.In software dsign, the dissertation design and implement several important embedded software of the filter control system such as sampled data processing and calculation for the main controller and the trigger-protector, switching control strategy for the main controller, zero-crossing checking for the zero-crossing switching board, CAN bus commnucition and PC monitoring. Sampled data processing and calculation includes fundamental, harmonics, active power, reactive power and other calculations, switching control strategy is based on actual customer demand, zero-crossing checking algorithm achieves fast zero-crossing, integrated Actual operation of the filter control system is in the substation of a plant. Run through a complete test proves the filter control system has high reliability and its switching effect is obvious, which can reduce the input harmonic into the power plant from routine power, and can achieve local consumption of harmonic current and reactive current of user’s power.