基于改进下垂控制的直流微电网功率均衡策略

A Power Balance Strategy of DC Microgrid Based on Improved Droop Control

下垂控制作为一种广泛应用的微电网控制策略,具有无需通信网络、即插即用等优点,但传统下垂控制存在着电流分配精度和母线电压平衡之间的固有矛盾。针对这一问题,提出一种改进下垂控制策略。首先,通过向变换器中注入交流小信号的方式,引入频率作为全局控制变量。然后,利用频率下垂和电压下垂特性,实现各分布式电源间的功率均衡;为了克服注入交流小信号所带来的电能质量问题,在系统达到稳定时停止注入交流小信号。最后,应用MATLAB/Simulink平台进行仿真,验证了所提控制策略在电流分配及维持母线电压等方面的有效性和可行性。

As a widely used control strategy for microgrids,droop control has notable advantages of dispensing with communication networks,plug and play,etc. However,there exists an inherent contradiction between current distribution accuracy and bus voltage balance in traditional droop control. To solve this problem,an improved droop control strategy is proposed in this paper. Firstly,by injecting AC small signal into the converter,the frequency is introduced as the global control variable;secondly,the power balance between DGs is realized in line with the characteristics of frequency droop and voltage droop. In order to improve the poor power quality caused by the injected AC small signal,the injection of AC signal is stopped when the system becomes stable. Finally,the effectiveness and feasibility of the control strategy in current distribution and bus voltage maintenance are verified by MATLAB/Simulink.