Study On The Adjustment To Unbalanaced Threephase Load In The Low Voltage Distribution Network Of SVG

With the rapid development of economy in our country,electrical equipment has entered every household in a large number,which makes the single-phase load increase and the three-phase unbalanced operation of low-voltage distribution network become more and more serious.It is a serious threat to the safe and stable operation of the power network.The reactive power compensation of power workers can be traced back to the era of synchronous condenser,but the equipment has many shortcomings.The technology of reactive power compensation has been reformed for several generations and advanced equipments such as static Var compensator have appeared,but it also has shortcomings.If the harmonic content is high and the three-phase can not be compensated in active power,after that,the static Var Generator was born.SVG is the most advanced reactive power compensation device at present.Compared with SVC,its reactive power compensation ability is basically not affected by the voltage fluctuation,and the device itself can hardly bring harmonics to the power network.And when the three-phase active power is unbalanced,the active power can also be adjusted.This paper first introduces the development of reactive power compensation device,and the current research results of SVG at home and abroad.Then,the structure and principle of SVG are described in detail.Finally,the simulation model of compensation device is established to simulate the compensation performance of SVG.It is the premise that SVG can adjust the unbalanced load effectively by obtaining the compensation current accurately.In this paper,several common reactive current detection methods are analyzed.Finally,a method is used to calculate the fundamental active current accurately even when the voltage is distorted.In the modulation,the twodimensional and three-dimensional vector modulation methods are studied,and the simple calculation is finally selected.Single modulation is an accurate modulation method,that is,three-dimensional space vector method in abc stationary coordinate system to modulate the compensation current.Based on the research of compensation current and modulation method,the simulation model of three-phase unbalanced compensation device SVG is established by using MATLAB simulation software,and several different loads are simulated to verify the compensation effect of SVG.The SVG designed in this paper has good compensation effect,when the load changes,it can adjust the compensation current in time and give correct feedback to the unbalanced system.