基于同步控制的微网多工况小信号稳定分析

Small signal stability analysis of synchronized control-based microgrid under multiple operating conditions

针对风机接入微网后较严重的频率稳定和功率平衡问题,提出微网环境下的双馈风机同步控制策略.在风机的转子侧,通过引入风机主动降载控制使双馈风机具有向系统提供功率备用和一次调频的功能,可以更有效地向微网提供频率支持.针对采用同步控制策略的典型风机-储能微网系统进行小信号稳定分析,计算得到的多工况主导特征根表明,微网的主导模式主要与风机轴系以及风机、储能控制内/外环两类控制参数密切相关.通过风速、负荷等扰动仿真分析表明:风机的降载运行有助于改善微网系统的小扰动性能,协调设计风机和储能的有功下垂系数亦可有效改善主导特征根的阻尼.

A synchronized control strategy of double fed induction generator（DFIG）in microgrid was presented to overcome the potential severe problems caused by the integration of large-scale wind turbine generators into microgrid,such as frequency instability and power imbalance.With synchronized control strategy,DFIG had the ability to provide power reserve,frequency regulation and effective support to the microgrid.Further,the small-signal stability（SSS）analysis of a typical microgrid system including DFIG and energy storage system（ESS）under the synchronized control was performed.The calculated dominant eigenvalues under multiple operating conditions indicate that the dominant modes are related to the DFIG shaft and the inner/outer control loop parameters of DFIG or ESS.Finally,the impacts of two types of key control parameters on the dominant eigenvalues were investigated,including the de-loading parameters and the active-power droop control parameters.Further simulation under wind speed variation and load disturbance indicates that the DFIG＇s de-loading operation can improve the system SSS performance.In addition,the coordination design of active-power droop parameters in DFIG and ESS can also improve the damping of the dominant eigenvalues.