Rule-based demand-side management of domestic hot water production with heat pumps in zero energy neighbourhoods

Abstract

Grid saturation has been reported in electricity distribution systems with a high penetration of photovoltaic (PV) systems. This saturation is often caused by overvoltage and results in curtailing or shutting down of the PV inverters, leading to a loss of renewable electricity generation. The presented work assesses the potential of rule-based demand-side management (DSM) applied to domestic hot water (DHW) production with heat pumps in dwellings for reducing the non-renewable energy use of the neighbourhood. The studied case consists of 33 single-family dwellings connected to a single phase distribution grid in a moderate European climate. Each dwelling is designed as a net-zero energy building by adequate design of a heat pump and PV system. A detailed dynamic simulation model is implemented by use of a cross-domain Modelica library for integrated district energy assessment. The user behaviour is obtained from a stochastic model based on Markov chains and survival analysis. Different rule-based DSM control strategies are applied to the individual dwelling's DHW systems. The results show that for balancing the PV production, active thermal energy storage in the DHW storage tanks is very promising. Even with very basic control algorithms and small storage tanks of 0.3 m3, curtailing losses can be reduced by 74%. This represents a net energy saving on a neighbourhood level of 3.4%.