Research And Design On The Low Voltage Hybrid Reactive Power Compensation System

With the rapid development of society,all kinds of power electronic devices and nonlinear loads are used in power system,and these produce a large number of reactive power.This may cause serious influence on the safe and economic operation of the whole power grid.Dynamic reactive power compensation technology has been rapidly developed and applied,which has great significance in improving the power factor of the grid,suppressing the collapse of the grid voltage,and ensuring the safe and stable operation of the grid.In the low voltage power supply system,three level Static Var Generator(SVG)and intelligent capacitor are two effective and widely applied reactive power compensation devices.It has important practical significance to realize hybrid reactive power compensation combing the advantages of the two devices.In this paper,the operating principle of two the kinds of reactive power compensation devices is studied,and the low voltage hybrid reactive power compensation method of SVG+intelligent capacitor is adopted.The reactive current detection,the key technology of SVG compensation control,the reactive power distribution control method and the design of experimental device of the hybrid system are studied respectively.In view of the problem that the response speed and the detection precision of the traditional ip-iq method can not be balanced,an improved ip-iq method is proposed to detect the reactive current,which is based on the Lorentzian function variable step size adaptive filter.The simulation and experiment results show that the proposed method has the characteristics of fast dynamic response and high detection precision compared with the traditional ip-iq method and other variable step size adaptive filter detection method.The PI control method has poor tracking performance for periodic signal and the repetitive control method will lead to the distortion of the compensation current when the load is mutated.In order to solve the problem,a weighted parallel repetitive control method strategy is proposed as the current tracking control strategy.Aiming at the complex computational process of three level space vector pulse width modulation method in 60 degree coordinate system,the improved method is adopted.The simulation results show that the improved modulation method simplifies the operation process,and the control strategy can eliminate the distortion of compensation current well.The power factor after compensation changes smoothly with small fluctuation.The operation characteristics of SVG and intelligent capacitor are analyzed.The basic principle of reactive power distribution is studied,and the specific principle of reactive power distribution is given.Based on this,a hybrid reactive power compensation simulation system is built,and the feasibility and correctness of the reactive power distribution control method are further verified by simulation.Finally,a hybrid reactive power compensation experimental platform is designed.The reactive power detection part,the three level SVG power compensation part and the intelligent capacitor are designed respectively.The corresponding software design is completed.Related experiments are carried out on the experimental platform.The experiment results show that the reactive current can be detected accurately and effectively compensated by the system.