Feasibility of Shiftable Loads: An Expansion of Deferrable Loads in Distribution Systems

With increasing integration of variable renewable energy resources, ensuring the reliability and stability of a distribution system has become a greater challenge. Through the use of deferrable load, utilities are able to delay a portion of the load of end-users during times of peak load in order to better stabilize the system. In a similar way, energy storage facilitates store energy during times of low demand and deliver energy during times of peak load. In this paper, shiftable load is introduced as an extension of deferrable load, which allows the utility to shift a portion of the end user’s peak load to a later or earlier time based on the load forecasts for the current day. By allowing this shift of load in both directions, the voltage stability of the system can be improved, along with savings on the cost of import. Furthermore, the addition of energy storage to shiftable load can further stabilize the voltages and reduce import costs. Simulation case studies on a modified IEEE 33-Bus test system including solar and wind generation, and energy storage systems, have been demonstrated to validate the effectiveness and efficiency of the proposed model.