Grid Impact of Different Types of Heat Pumps

Abstract

The Netherlands is committed to reducing carbon emissions in all sectors. This will cause the electricity production to be dominated by wind and solar power, and sectors such as mobility and industry will be heavily electrified. This poses significant challenges for the electricity grid. In addition, the government plans to phase out the use of natural gas in buildings by 2050. Local governments are now choosing alternative heating sources for specific neighbourhoods, and heat pumps are one of the options. As these use electricity for heating, it is important to consider their impact on the grid.

Therefore, this thesis analyses the impact of different types of heat pumps on a real Dutch low-voltage grid, focussing on transformer overload and voltage limit problems. A simulation model based on Powerfactory and Python is built, where different types of heat pumps are considered, including air- and ground-source heat pumps, as well as electric-resistive and natural gas hybrid heat pumps. Different control methods are also considered. In addition to heat pumps, public and private electric vehicle chargers and photovoltaic systems are also included in the model. Additionally, the effects of dynamic energy prices and domestic hot water production are investigated. The simulation is performed on an hourly basis using real data from the two coldest weeks of the winter of 2021.

The results show that air-source heat pumps have a significantly higher impact on transformer overload and voltage limit violations than ground-source heat pumps, and modulating heat pumps have a slightly lower impact on the grid than on-off controlled heat pumps. Gas-hybrid heat pumps are found to cause almost no grid problems on the low-voltage grid studied and have a significantly lower impact than the all-electric air-source heat pump. The presence of an electric-resistive backup heater in the heat pump significantly increases transformer overload and voltage limit problems. Scenarios for 2030 and 2050 show that problems are unlikely to occur in 2030, but the current grid will not be sufficient in 2050 if air-source heat pumps dominate the grid. More research is needed to determine whether the current grid is sufficient when ground-source heat pumps are dominant.

It was also found that dynamic energy prices will not be a problem for the grid at current rates of heat pump and home charging for electric vehicles. However, if every household has a heat pump, a penetration rate of 20\% or more of dynamic energy contracts will substantially increase transformer overloads and voltage level violations. Finally, domestic hot water production does not significantly increase overloading and voltage limit problems.

In conclusion, heat pumps can cause significant problems for the low-voltage network. However, the impact can be reduced by choosing the right type of heat pump. It is recommended that future research considers cooling, heat and electricity storage, thermal ratings of transformers, and variable capacity tariffs.