Research On Electric Vehicle V2G System Based On Virtual Synchronous Generator Control Strategy

New energy vehicles,especially electric vehicles,are becoming more and more popular,which is accompanied by the huge energy storage potential of electric vehicle batteries.If it can be applied to the active distribution network of grid,it will greatly benefit the voltage and frequency stability of the power grid,resulting in huge economic benefits.V2G(Vehicle-to-Grid)technology has subsequently become a hot spot for research at home and abroad.The important basis for the realization of V2G system lies in the reliable converter topology and effective control method.Most of the existing charging pile converter topologies are Vienna circuits.A bidirectional Vienna topology is designed in this paper,which can realize the bidirectional flow of converter power.In this paper,the six diodes of the Vienna circuit are changed to IGBT,and two mode conversion switches are added to the connection of the two bridges,so that the circuit is still a three-level Vienna circuit during rectification and charging.Meanwhile,it is converted into a bridge inverter circuit when feeding,which realizes the bidirectional flow of power.This paper builds a simulation model of this topology in Psim,which verifies the correctness of the bidirectional topology.This paper analyzes the existing control methods of the charging pile converter.In view of the characteristics of low inertia and low damping characteristics when electric vehicle incorporated into the active distribution network,this paper selects the Virtual Synchronous Generator(VSG)strategy as control strategy.This paper analyzes the working principle of common VSG control technology and discusses the problems of d-q transformation in common VSG control.Aiming at the characteristics that V2G systems usually work in non-island mode and can be supported by the power grid with voltage and frequency,a VSG control technology suitable for V2G is proposed.This control strategy simplifies the common PQ-U-I three-loop control of the common VSG control to the PQ-I dual-loop control.It simplifies the control loop and realizes the constant connection mode Power Control.The article gives a mathematical model analysis of the control scheme,and analyzes the control strategy.Subsequently,the article verified the correctness and effectiveness of the control strategy through simulation.It provides a control method for dealing with the problem of lack of inertia and damping in V2G systems in low-voltage distribution networks.Finally,this paper builds a small power experimental platform to verify the effectiveness of the proposed VSG control strategy,designs the main circuit,drive circuit,sampling conditioning circuit schematic and PCB,and writes the system software control program.The effects of different inertia parameters and damping coefficients on the system inertia are analyzed through experimental results.The experimental results are close to the simulation conclusions,verifying that the VSG control can effectively improve the inertia and stability of the V2G system.