Variable speed heat pump design for frequency regulation through direct load control

Frequency regulation becomes a non-trivial issue due to an increase in renewable resources and power electronics-based loads. Direct load control (DLC), a strategy of autonomous demand response, has been applied to mitigate operational burdens on generation units for frequency regulation. Variable speed heat pumps (VSHPs) have been regarded as promising devices that can respond to the DLC signal updated every 2 or 4 seconds. This paper presents a dynamic model of the VSHP that is simplified for real-time simulation studies but still sufficiently comprehensive to analyze its physical and operational characteristics. Furthermore, a variable speed drive (VSD)-controlled induction motor model is designed together with an indirect torque controller for the adjustment of the VSHP input power. In addition, based on experimental setup and data, a test room was modeled to estimate the effect of the DLC-enabled VSHP on indoor temperature. Simulation case studies performed in Matlab/Simulink verify that the VSHP can be well utilized as DLC-enabled loads for frequency regulation while ensuring residents´ comfort and long-term device performance.