随着环境污染问题和能源危机的加剧，越来越多的分布式电源接入电网，而大量的分布式电源接入传统电网会使电网输入和输出功率不匹配，从而造成频率和电压幅值波动严重，威胁了电网电压的稳定。
问题：电流源并网孤岛运行和电压支撑能力差，短时过载能力弱，转动惯量小。（电压支撑能力、故障恢复能力、频率稳定性）
为维持电网输入输出功率平衡及频率稳定，一些学者提出了虚拟同步电机(Virtual Synchronous Generator，VSG)的概念，以增大系统惯性，增强系统的电压频率和幅值的支撑能力。(With the problem of environmental pollution and energy crisis, more and more distributed power grid, and a large number of distributed power grid will make the grid connected to the traditional input and output power do not match, resulting in frequency and voltage fluctuation is serious, threatening the stability of the grid voltage.)