Realizing load reduction functions by aperiodic switching of load groups

This paper investigates the problem of scheduling ON/OFF switching of residential appliances under the control of a Load Management System (LMS). The scheduling process is intended to reduce the controlled appliances' power demand in accordance with a predefined load reduction profile. To solve this problem, a solution approach, based on the methodology of Pulse Width Modulation (PWM), is introduced. This approach provides a flexible mathematical basis for studying different aspects of the scheduling problem. The conventional practices in this area are shown to be special cases of the PWM technique. By applying the PWM-based technique to the scheduling problem, important classes of scheduling errors are identified and analytical expressions describing them are derived. These expressions are shown to provide sufficient information to compensate for the errors. Detailed simulations of load groups' response to switching actions are used to support conclusions of this study.