The Control Strategy On Combined Reactive Power Compensation

In recent years, inductive, non-linear, impact load are widely used. Theyproduced a lot of reactive power demand, resulting in reducing grid power factor,decreasing voltage stability and seriously affecting the quality of the grid. Dynamicreactive power compensation can effectively improve the power factor, stable powergrid voltage. It is very important in transmission and distribution systems.Thyristor switched capacitor (TSC) and Static Var Generator (SVG) are twoimportant and widely used reactive power compensation device. Considering therunning characteristics and economy of the two devices, a modular topology isproposed. A control strategy for this combined system is studied to coordinate andensure an orderly work to fulfill fast large capacity dynamic reactive powercompensation.This article first analysed and selected TSC and SVG circuit topology andcontrol algorithm. The main circuit topology of TSC is Triangle Connection. Basedon the analysis of the transient process of switching capacitor, zero thyristor voltageswitching TSC control algorithm is proposed. The topology of SVG usesvoltage-bridge inverter circuit, selecting the timing controled instantaneous valuecomparing as direct current control strategy. The control precision is high andreactive output current responses speedly.Based on the analysis of combined system operating characteristics,coordinated control strategy is proposed in this paper, consisting of coordinationlayer, reactive control layer and perform layer. A combination of the open-loopcontrol and closed-loop control is used in reactive current detection. The use ofinstantaneous reactive power algorithm ensured quickly and accurately reactivecurrent detection; details of the reactive power distribution principle are given. TSCand SVG coordinated work produced a corresponding compensation current.MATLAB simulation analysis further verified the feasibility of the control strategy.At last, relevant experiments are done on the experimental platform.Experimental results show that the system can achieve accurate and fast largecapacity reactive power compensation, during the compensation process, SVG andTSC work coordinately, systematic compensation effect and dynamic responsespeed requirements are met.