基于双回柔性直流两区域异步互联系统频率一致性控制

Frequency Consensus Control for Two-area Asynchronous Interconnected System Based on Double-loop

为提高基于双回柔性直流两区域异步互联系统电网频率稳定性,提出一种基于“就地控制”与“上层集中”相结合的频率一致性控制。“上层集中”控制层通过对就地电压及功率信息进行处理及控制,为“就地控制”层提供直流电压参考及辅助功率参考;“就地控制”层在常规控制基础上,两端换流站均引入通用化频率-电压辅助控制结构;同时引入直流电压信号调整系数α。最后,通过PSCAD/EMTDC仿真,验证了所提策略可有效改善受扰电网频率动态特性,实现了系统旋转备用共享,同时实现了紧急支撑功率由双回线路依据其备用容量比进行承担,电压信号可灵活切换,提高了通信故障等紧急工况下系统可靠性。

To improve the grid frequency stability of a two-area asynchronous interconnected system based on doubleloop,a frequency consensus control based on“local control”and“upper coordination”is proposed in this paper.In the“upper coordination”layer,the DC voltage and auxiliary power references for the“local control”layer are provided by processing and controlling the collected local voltage and power information.In the“local control”layer,a general auxiliary frequency-voltage control structure is introduced to both the voltage-terminal and power-terminal VSCs on the basis of the traditional control.Meanwhile,a regulation coefficientαof DC voltage signals is introduced to the“local control”layer.Finally,the simulation results in PSCAD/EMTDC verify that the proposed strategy can effectively improve the dynamic characteristics of the disturbed grid frequency,thus realizing spinning reserves sharing and the emergency power of DC system that can be reasonably shared by the double loops according to their own reserve capacity ratios.In addition,a flexible switching between voltage signals can be realized,which enhances the system reliability in urgent conditions such as communication failure.