Studies On The Low-Voltage Dynamic Reactive Power Compensation Device

Due to increasing loads of electric power system, demand on reactive power was also increasing. Because transmission of reactive power in electric network can lead to network loss and step-down voltage, resulted in reduction of using efficiency of power energy and severely effected voltage quality. It became necessary means that reactive power compensation devices were installed in proper position of electric network.This paper introduced the principle and objective of var compensation, and presented the developmental actuality and trend of reactive power compensation system. Based on compensation principle and connection way, this paper studied switches of capacitors and the model of reactive power optimization planning about low voltage system. Based on analysis of other criterion methods, the paper introduced fuzzy control into var compensation. This new method can manage the relationship between voltage quality and power factor properly and eliminate the repeatedly switching problem.A TSC reactive power compensation device which was fit for low-voltage distribution network was introduced in this paper. The compound criterion whose main criterion is reactive power and whose assistant criterion is voltage was applied in the device, which effectively overcame the defects of the power factor criterion in which switching oscillation was often resulted in under light load and compensation was insufficient under heavy load, and the compound criterion gave attention to decreasing power loss and improving voltage quality.The system adopted thyristor as switch that connect capacitors to main circuit, and the Thyristor was triggered by a special device in the zero-voltage condition and thus greatly reduced surge current. This sort of switch circuit achieved switching of capacitors without transition course and was simple and reliable. The device took the AT89C51 which is a sort of cheap single chip micro-controller as main control chip. This device could fleetly and truly compensate reactive power and was low-cost. It processed preferably practicability and wide application foreground in low voltage network.At last, the device was simulated through software MATLAB/Simlink, and simulation and experiment show that the basic principle and method was totally feasible and effectual.