Experimental study on demand response by use of commercial heat pump water heater in SPA facility

Recent increase of variable renewable energy sources such as photovoltaics and wind turbines makes balancing power supply and demand difficult. One of the methods to support balancing supply and demand in power grid is demand response. In this research, demand response by use of heat pump water heater (HPWH) in spa facility was considered. To predict power consumption of HPWH, HPWH was modeled using real operation data. Hot water demand model was also made using real operation data to predict hot water consumption and avoid hot water shortage. Using both HPWH and demand model, daily operation schedule which satisfies both demand response requirement and spa users' convenience. Demand response experiment was conducted to evaluate demand control error and effect on users' convenience. From the result, daily operation schedules were generated and HPWHs were operated without water shortage. However, power consumption errors occurred due to HPWH model error, water demand error, input ambient temperature error and reheat operation. In the future, power consumption errors will be reduced to increase accuracy of input ambient temperature and consider tank heat loss into operation schedule. © 2019 The Institute of Electrical Engineers of Japan.