Combined frequency regulation control of electric vehicles and thermal power units based on VMD and MPC

Reasonable signal allocation strategy and effective signal tracking control method are the keys to using aggregate electric vehicles (AEVs) combined with thermal power units to perform the control, improve the quality, and enhance the economy in frequency regulation. Therefore, a frequency regulation control strategy with the participation of AEVs is proposed based on variational mode decomposition (VMD) and double-layer model predictive control (MPC). Firstly, the coordinated optimization control structure of AEVs combined with traditional thermal power units is designed for frequency regulation. The models for thermal power units and load frequency control are established. The AEVs are converted into virtual frequency regulation units, and the load frequency control model of single-area multi-unit with the participation of AEV is constructed. Then, the frequency regulation signal is decomposed into intrinsic mode functions with different frequency components using VMD. The high-frequency components and the low-frequency components are integrated as the frequency regulation signals of AEVs and thermal power units respectively. Optimal redistribution and tracking control of frequency regulation signals within AEVs and thermal power units are realized by double-layer MPC, respectively. Finally, the proposed control strategy is verified by the simulations, and the results show that it can adjust the system frequency effectively and keep a balance between the economy and dynamic performance in frequency regulation.