Reactive Current Detection And Control Method Research Of Static Var Generator

With the using of power electronic device and nonlinear equipment, and the continuous increasing demands on power quality by customers, the reactive compensation of power quality become more and more important. In power electronics, it is one of the most active areas that researches into realizing dynamic reactive compensation by static var generator (SVG). At the present time, the research on SVG is mainly focus on the reactive compensation of power transmission system, and the control method is based on indirect-current control. In our country, it is very little that the SVG is applied to low-voltage distribution system and load compensation for industry. Relative mature product has been offered by some foreign manufactures and scientific research institutions, but the price is very high.Based on the low-voltage distribution system or load compensation for industry, the aim of the thesis is to study the SVG that adopts direct-current control.In this thesis, the SVG has been studied and analyzed deeply. Firstly, the existing compensation devices have been compared and the superior performance for SVG is analyzed. According to dynamic compensation principle on SVG, characteristic of SVG based on direct-current control is analyzed. At the meantime, the compensation performance for SVG is discussed and the math deduction based on switch function and d - q coordinate is given in detail. Secondly, in this thesis, a structure of BP Neural Network for detecting reactive current is designed and the corresponding algorithm is given. Then, the thesis generalizes typical control methods of indirect-current control and direct-current control. After analyzing the merits and drawbacks of these control methods, a control strategy which combines voltage loop, current loop and phase-locked loop is put forward. Before giving Design method of analog governor and digital governor, error governor in control strategy has been analyzed and studied. In the end, selection of the main circuit structure and the design method of corresponding parameter for SVG are given. The hardware circuit based on DSP digital control system is designed and corresponding algorithm routine is given.