Modelling and design of a virtual energy storage system (VESS) for power system frequency regulation

The thermal control loads such as air conditioner can be treated as a Virtual Energy Storage System (VESS) to provide valuable frequency regulation for power systems with intermittent renewables. This paper proposes a thermal model of a VESS to mitigate the high-level wind power fluctuations in a distribution network so as to regulate system frequency. A center-free control scheme based on the consensus algorithm is designed for VESSs to share the fluctuating wind generation in a fully distributed manner. The scheme is robust and flexible to users’ practical behaviors including switching off and switching on of air conditioner, maximum and minimum temperature set by users. Massive simulations on a distribution network with coal and diesel generators, several wind farms and 50000 VESSs in 10 buildings demonstrate that the proposed VESS control scheme could effectively regulate the system frequency in the real time while the customers’ requirements could be satisfied.