Research On Reactive Power Compensation Of Electric Vehicle Charging Station Based On SVG

With the rapid development of power industry,the influence of nonlinear load and unbalanced access on power quality is more and more,and the reactive compensation device is more and more widely concerned,especially for static Var generator,it has its superior performance and unlimited development space,and it has been universally recognized by the power sector.The static Var generator is of great significance in the field of reactive power compensation because of its high performance dynamic reactive compensation characteristics.This paper is aimed at the reactive power compensation research of the static var generator in the electric vehicle charging station.This article first introduces the engineering background of the electric vehicle charging station,then through the comparison and analysis of several kinds of reactive power compensation equipment,the importance of static Var generator used in electric vehicle charging station as reactive compensation device is determined.Then,the topological structure and working principle of the static var generator circuit are analyzed,and the input-output dynamic mathematic model is established based on three-phase third-wire system.Secondly,this paper introduces the method of reactive current detection and control strategy of SVG,and through analyzing several methods of reactive power detection,the p-q detection method based on instantaneous reactive power theory,the ip-iq detection method and the d-q detection method under dq Coordinate transformation are established by search coordinate transformation.In the unbalanced charging load access system,a d-q double sequence synchronous detection method is proposed.In the aspect of control strategy,this paper compares the advantages and disadvantages of direct current control and indirect current control,and designs the d-q synchronization control strategy under unbalanced mode.The direct current control strategy of dq coordinate transformation based on triangular wave is compared,and the control method is double closed loop control,i.e.voltage outer loop control and current inner loop control.Moreover,the feed forward decoupling control of positive sequence and negative sequence is used to separate tracking control active and reactive current instruction signals,and the d-q synchronization control strategy is studied in detail.The basic composition of the electric vehicle charging station is analyzed.According to the principle of the charger,the topological structure of the charger is simplified and theequivalent model is built.The reactive power compensation is then carried out for the charging load of the AC charging pile in the electric vehicle charging station in an unbalanced way.Through the simulink simulation software analysis and verification of the balance mode and unbalanced mode of operation,simulation results show that the application of SVG in the charging station system for reactive power compensation is feasible.