Virtual Energy Storage: Converting an AC Drive to a Smart Load

This paper proposes a new smart-load concept using ac drives. The concept is based on a secondary control layer coordinated with the network and the load to provide active power support. The general smart-load concept is developed and synthesized for its practical implementation in network power-frequency support applications. A multi-power-frequency droop line is proposed. The final idea is applied to a fan load powered by an ac drive based on an induction motor and a two-level voltage source converter. Experimental results show that a full power-frequency response can be achieved by the smart load within 2 s of the network frequency deviation.