Topical Article: The role of Heat Pump Control in Decentralized Energy Flexibility Exploitation

In 2019, the combination of space heating/cooling and domestic hot water accounted for more than 75% of the final energy consumption within the European residential sector, while the residential heat pump market share was only 6% at the end of 2020. Fuel burner replacement by heat pump (HP) allows further decarbonization of the energy sector while increasing the renewable energy production allows a more sustainable energy provision as well. Due to their market potential, renewable character and coupling to the electricity grid, HPs are seen as one of the appropriate technologies for energy flexibility services.

Though, reaching an accurate short-term behavior control of HP is not straightforward as HP manufacturers already implement internal control strategies to ensure safety, reliability, and satisfaction of the end-user comfort. As grid users will be allowed to trade energy and flexibility services in the near future, an accurate estimation of the actual HP behavior is thus required. Though the coupling with the wholesale energy market is mainly kept for energy security and to allow users to buy/sell energy from/to energy retailers.

A comparison of HP modeling approaches showed that an accurate energy performance representation is the main focus within the literature, while internal control strategies are mainly neglected. A calibrated model and experimental measurements can be used to develop a digital twin of the HP. Digital twins permit end-users or an energy management system to determine the HP behavior with a limited set of hardware requirements. Focusing on the HP control during energy trading, the digital twin is used to determine the energy level and related price.

A potential solution for HP electricity consumption control, while leaving the direct control up to the manufacturer, is the implementation of onboard flexibility interfaces. Hence, without any knowledge of such behavior, an estimation of the amount of flexible energy is rather difficult to obtain. Finally, as variable capacity HP allows to modulate their power, the part-load efficiency influences the price of the offered energy flexibility. A preliminary step is to obtain an accurate knowledge of the heat pump’s internal control strategies, already implemented by the manufacturer, as these control rules can generally not be bypassed. Also, energy trading by end-users in microgrids requires an accurate estimation of the heat pump behavior and energy flexibility potential during the trading interval.

Maarten Evens, Alessia Arteconi, KU Leuven, Belgium
The text has been shortened by the HPC team

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