Grid-connected converter is important for distributed generation and microgrid technology in ac system.However,traditional control strategies of grid-connected converter ignores its differences with synchronous generator,which results in excessive rate of change of frequency and other undesired frequency performance.Therefore,virtual synchronous generator is proposed,which aims to imitate synchronous generator to improve frequency dynamics by storages.Considerable researches have investigated virtual synchronous generator control strategies,where active power control and reactive power control are implemented by frequency regulation and voltage regulation respectively.The results suggest its efficiency in relieving frequency problems.This paper discusses control strategies of virtual synchronous generator in voltage control and current control mode,where the active power control corresponding to inertia,droop and damping control and reactive power control are discussed respectively.%由于传统并网变流器控制技术忽略了与同步发电机在旋转惯量等特性上的差异,导致并网运行时的频率变化率过快、频率动态性能不佳,提出虚拟同步发电机的控制策略.讨论了当前不同电压控制型和电流控制型的虚拟同步发电机控制策略,并基于同步发电机的运动方程与电气方程原理,具体介绍VSYNC项目方案、VISMA电流控制及电压控制型方案、KHI代数型方案、Synchronverter方案、虚拟惯性频率方案和ISE实验室方案有功功率控制策略,以及对应的惯性、下垂和阻尼控制方法,并对以上研究当中的无功功率控制方法做简要概述.
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