同步定频微电网无通信二次调压策略

Secondary voltage regulation strategy of synchronous fixedfrequency microgrid without communication

同步定频微电网采用电流电压(I-U)下垂控制策略易于实现分配功率、消除频率偏差。但在孤岛模式运行该策略时,负荷变化会引起电压波动。文章提出了基于就地信息的同步定频微电网二次调压策略,根据可调度型分布式电源(Distributed Generation,DG)出口实时电压动态调整下垂曲线,实现DG输出电压的二次调节,使负载端电压始终在设定的范围内。针对无通信条件下可能出现的多个DG调整下垂曲线动作不同步的问题,提出了基于卫星授时信号同步调整下垂曲线的方法,微网内各DG同步检测就地电压,同时根据线路阻抗大小设计各DG输出电压最大、最小阈值,使各DG同步调整下垂曲线。二次调压策略对功率分配影响较小,且可以提高DG输出功率。Simulink仿真和实验结果验证了所提二次调压策略的有效性。

The synchronous fixed-frequency microgrid adopts current-voltage(I-U)droop control strategy,which is easy to distribute power and eliminate frequency deviation.However,when running this strategy in the island mode,the load change will cause voltage fluctuation of the microgrid.The article proposes a synchronous fixed-frequency microgrid secondary voltage regulation strategy based on local infor-mation.The droop curve is dynamically adjusted according to the real-time voltage at the outlet of schedulable distributed generation(DG)to realize the secondary regulation for the output voltage of the DG,so that the voltage at the load end is kept within the set range all the time.Considering the problem that the actions of multiple DGs adjusting the droop curve may not be synchronized under the condition of no communication,a method of synchronously adjusting the droop curve based on satellite time service signal is investigated.To be specific,each DG in the microgrid synchronously detects the local voltage,and the maximum and minimum threshold of output voltage of each DG is designed according to the line impedance which will make each DG adjust the droop curve synchronously.The secondary voltage reg-ulation strategy has little influence on power distribution and can improve the output power of DG.Finally,the simulation by Simulink and experiments are carried out and the corresponding results verify the effectiveness of the secondary voltage regulation strategy proposed in this paper.