Non-Disruptive Load-Side Control for Frequency Regulation in Power Systems

This paper studies frequency regulation of power systems by using both automatic generation control (AGC) and load-side control. A switched distributed controller is designed for each load bus in a transmission network. The targets of the designed controller are twofold. First, it makes controllable loads work together with generators to restore the system frequency quickly after a real power mismatch occurs in the grid. Second, it restores controllable loads to their nominal working conditions. To achieve the first target, a consensus-based distributed load-side controller is designed. Peer-to-peer communication between loads is used to achieve an average consensus according to which controllable load reacts to the frequency deviation. To achieve the second target, the load-side controller shifts its duties to AGC slowly after the frequency goes back into an ideal region, and hence, controllable loads will restore to their nominal conditions gradually. A switching signal is designed to detect time instants when the load-side controller should work in the mode of frequency restoration or in the mode of load restoration.