基于混合储能的孤岛微网VSG控制策略

针对虚拟同步发电机(VSG)控制策略中改变惯性系数会引起系统不稳定的问题,提出基于混合储能无需改变惯性系数的控制策略。首先,在常规VSG控制策略基础上,将负荷或可再生能源波动量经一阶高通滤波器滤波后作为常规VSG额定功率的附加量。其次,利用VSG直流端接入的蓄电池提供下垂功率,超级电容器提供虚拟惯性功率和额外引入的惯性功率,改善微网的频率动态特性。然后,引入与超级电容器荷电状态和额外惯性功率相关的出力系数,实现超级电容器的自适应控制,在惯性强化过程中优化超级电容器荷电状态。最后在Matlab/Simulink中搭建了以VSG为逆变器控制接口的孤岛微网,通过在不同负荷、光照强度和超级电容器荷电状态下进行仿真,验证了所提策略的有效性。

VSG control strategy of an isolated microgrid based on hybrid energy storage

Changing the inertia coefficient in the Virtual Synchronous Generator (VSG) control strategy will cause system instability. Thus a hybrid energy storage-based control strategy without changing the inertia coefficient is proposed. First, the load or new energy fluctuation is regarded as the additional quantity of VSG rated power after passing through the first-order high pass filter as with a conventional VSG control strategy. Secondly, the battery connected to the DC terminal of the VSG is used to provide droop power, and the super capacitor provides virtual inertial power and additional inertial power. This improves the frequency dynamic characteristics of the microgrid. Then, the output coefficient related to the state of charge of the supercapacitor and the additional inertial power is introduced to realize the adaptive control of the supercapacitor and optimize the state of charge of the supercapacitor in the inertia strengthening process. Finally, an islanded microgrid with VSG as the inverter control interface is built in Matlab/Simulink. The effectiveness of the proposed strategy is verified by simulation under different loads, light intensities and supercapacitor states of charge. This work is supported by the National Key Research and Development Program of China (No. 2018YFB0905304).