Power Hardware-in-the-Loop Simulation Study on Frequency Regulation Through Direct Load Control of Thermal and Electrical Energy Storage Resources

Variable-speed heat pumps (VSHPs) and battery energy storage systems (BESSs) have been considered as promising energy storage resources (ESRs) that can be used for grid frequency regulation (GFR) through direct load control (DLC). In this paper, a power hardware-in-the-loop (PHIL) simulation setup has been developed to analyze the effects of real DLC-enabled VSHP and BESS units (not simulation models) on real-time GFR. Using the PHIL application, the dynamic response characteristics of the complicated hardware units have been comprehensively incorporated into the GFR analysis. In addition, a new real-time GFR scheme has been proposed to reduce the frequency deviation and the required reserve capacity of generators in a laboratory-scale islanded microgrid. In the proposed GFR method, the fast-response BESS compensates for the high-frequency components of load demand variations, while the rotary VSHP and the conventional generators are controlled to mitigate the low-frequency variations. PHIL simulation studies have been performed to compare the conventional and proposed GFR schemes under various conditions. The simulation results show that the VSHP and BESS can be effectively exploited as DLC-enabled ESRs to improve frequency stability.