Smart management of domestic storage water heater electrification to minimise impact on distribution networks

Increased transport and heating electrification are reported to cause adverse voltage and system loading impacts on electricity distribution networks. This study proposes and demonstrates a novel smart management strategy of domestic electric storage water heaters (EWH) using a 546-bus test distribution network, with the purpose of reducing electrification impacts on the network voltage and system loading. The study first analyses the performance of an electrical distribution network using gas water heaters (GWH) as a baseline. We then apply progressively smarter electric water heating thermodynamic profiles, beginning with traditional EWH, heat pump (HP), and finally coupling intelligent EWH with photovoltaics. Hot water thermodynamic modelling is performed using TRNSYS software to determine new load profiles. Distribution network modelling is performed using DIgSILENT PowerFactory software to assess the grid's response to adjusted water heater management strategies. Simulation results show a significant increase of voltage violations (from 3.8% to 13.7%) when GWH are converted to EWH, particularly after midnight. Transitioning from EWH to HP improves the overnight network voltage performance but exacerbates it during peak consumption hours from 17:00 to 22:00, increasing violations to 26.2%. In both EWH and HP cases, line loading increases beyond 100%. Coupling PV with EWH at the most affected locations reduces the overall voltage violations to 3.5% but does not solve the overnight voltage problems. However, deploying 9% of smart EWH that intelligently operate in periods of excess PV generation at the most affected locations essentially eliminates network voltage violations at the weakest bus. • Detailed coupling of hot water thermodynamic models with distribution network model • Quantification of effects of domestic electric water heating on the power grid • Heat pumps and PV-coupled water heaters need further controls to improve voltage. • Smart management of electric water heaters at key buses shows better network voltage. • 9% network deployment reduces violations from 26% to almost zero at the weakest bus.