基于虚拟同步发电机的微电网延时补偿二次频率控制

Secondary Frequency Control Including Delay Compensation in Microgrids Based on Virtual Synchronous Generator

虚拟同步发电机控制能够为电网提供虚拟惯量,提高系统的频率稳定,但在通信线路传输延时的影响下,传统二次频率控制动态特性显著恶化。建立包含二次调频环节、通信延时环节的微电网完整小信号状态模型,基于该模型对虚拟同步发电机接入后的微电网频率稳定进行了研究,讨论虚拟惯量等重要控制参数对微电网频率控制延时边际的影响。针对通信延时对频率控制的负面作用,设计含虚拟同步发电机的微电网延时补偿二次频率控制策略,在原有控制回路中增加延时响应预测环节以补偿通信延时影响。利用PSCAD/EMTDC仿真对比了是否包含延时补偿下系统的频率响应,结果表明所提延时补偿控制策略能够有效提高微电网频率控制对通信延时的鲁棒性并增强系统的频率稳定。

Virtual synchronous generators can provide the virtual inertia for the power network to improve the frequency stability.However,the delays in communication lines will deteriorate the performance of the traditional secondary frequency control.The whole small-signal model including secondary frequency control and communication delay was built and used to investigate the impacts of the virtual synchronous generator on microgrid stability.The effects of the important control parameters such as virtual inertia on the delay margin were discussed.In terms of the negative effects of the communication delay,a corresponding delay compensation strategy for virtual synchronous generator was proposed to compensate the impacts of communication delay,where a predicting loop was added to the control.The comparisons of simulation results in PSCAD/EMTDC on dynamics with and without the communication delay compensation were carried out.It is shown that the proposed control strategy can effectively improve robustness of the microgrid frequency control on the communication delay,and enhance the frequency stability.