基于改进下垂法的微网并网控制策略研究

Research on control strategy of micro-grid-connected based on the improved droop method

分布式微网并网控制策略研究对提高微网可靠运行有重要意义。针对微网系统孤岛运行时分布式电源间存在环流的问题,设计了无功环流抑制环节以改进下垂控制,通过平移下垂控制曲线实现了分布式电源在并网模式下的恒功率输出,在此基础上设计了并网预同步控制器,以保证并网时不会对电网产生大的冲击电流,最后,在Matlab/Simulink中对微网孤岛运行时无功环流的抑制、微网运行模式切换时的控制及微网并网后的恒功率控制进行了建模仿真,结果验证了改进下垂控制法的正确性和可行性。

Study on distributed micro-grid-connecting control strategy has important significance to improve the reliability of micro-grid operation. In terms of loop current that existed in distributed generation when micro-grid system is under island model,restrain link of reactive loop current is designed for improving droop control,constant power output of distributed generation under grid-connecting model is realized through translating droop control curve in this paper,and on this basis,grid-connected presynchronization controller is designed for insuring that there won＇t be great shock current when grid is connected. At last,the restrain of constant loop current during island model operation,control of switching under microgrid running model and constant power control after micro-grid is connected are simulated through Matlab / Simulink. The results verify the validity and availability of the improved droop control method.