Quantification Method For The Potential Downward Flexibility of Full-Electric Heat Pumps During Congestion Events

The increasing number of full-electric heat pumps (HPs) could potentially lead to congestion issues in future distribution grids. However, most modern HPs have the possibility to reduce demand during expected congestion events in a flexible manner. This study proposes a new approach for characterizing the potential downward flexibility of full-electric air-water heat pumps during parameterized congestion events. The congestion events are characterized by their start time, duration, and moment of announcement. Better insights into how these factors influence the downward flexibility of HPs can guide grid operators to assess whether grid reinforcements or flexibility activation is a better solution to address the expected congestion. The method combines a rule-based and an optimization-based (mixed-integer linear program) control strategy for baseline and flexible operation respectively. It produces power shift profiles over the congestion event, which give a more complete characterization of the downward flexibility than existing flexibility metrics. Using the new method, it is shown that the two studied modern Dutch buildings were completely able to reduce their baseline load for the first 2 hours of every congestion period in the year 2020. Furthermore, by announcing the congestion 2 hours prior to the event, a median energy reduction of 84% could be achieved during a congestion event of 6 hours in December 2020.