中文摘要：

针对传统下垂控制器在微网并网模式运行时受电网频率或电压幅值波动的影响，难以实现恒功率输出的问题，提出了一种动态调节下垂系数实现恒功率输出的控制策略。同时为平抑微网孤岛模式运行时因连网线路阻抗不同而产生的环流设计了无功环流抑制单元。此外，为了保证微网在运行模式切换时平滑过渡而设计了预同步控制器。所提出的控制策略通过Matlab／Simulink仿真平台验证了其正确性和可行性。

英文摘要：

The conventional droop controller is difficult to achieve the constant power output on the micro-grid grid-connected operation mode when the frequency or voltage magnitude of the grid fluctuate, the improved droop control scheme which can dynamically adjust the drooping coefficient is proposed for realizing the con- stant power output on grid-connected mode. At the same time, a suppressor is designed to suppress the reac- tive circulation current on island operation mode caused by the different connection impedance. Moreover, a pre-synchronizing controller is designed for insuring micro-grid smooth transition between the island operation mode and grid-connected operation mode. Lastly, the proposed control scheme have been validated in accuracy and feasibility by Matlab/Simulink simulation.