Primary Frequency Control in Isolated Microgrids Using Thermostatically Controllable Loads

Abstract

Hybrid renewable energy sources (RES)-diesel systems are now being considered as an economic, attractive and clean option for remote isolated microgrids, to offset diesel consumption by displacing generation from conventional units; however, system security and stability is a challenge as the penetration of RES increases. In this context, Demand Response (DR) can be used to increase grid flexibility, improve efficiency, and facilitate the penetration of RES. Thermostatically controllable loads (TCLs), i.e., electric water heaters (EWHs), air conditioners (ACs), and ground source heat pumps (GSHPs), are ideal candidates to participate in such a DR strategy, since their power consumption can be controlled without affecting consumer comfort. Therefore, this paper presents novel, computationally efficient, and adequate thermo-electrical dynamic models of ACs and GSHPs, along with an existing model of EWHs, to adapt and improve a decentralized DR strategy for Direct Load Control (DLC) for primary frequency regulation in hybrid isolated microgrids. Different cases studies are presented for a real microgrid to analyze and compare the system frequency response and determine the adequacy of the proposed approach and models, demonstrating their effectiveness for primary frequency control provision to facilitate higher RES penetrations.