Undesired effects of widespread implementation of control and optimisation algorithms in residential electricity grids

The power system is becoming increasingly volatile due to the rise of variable renewables and electrification of demand. Rather than controlling a small number of large-scale generators tuned to demand, multiple smaller generators and large parts of the demand itself need to be controlled. Many kinds of control algorithms will emerge in parts of the power system that will affect each other, possibly in undesirable ways. This paper presents a case study demonstrating the unintended negative effect that home batteries can have on the grid. The simulations consist of households with a rooftop photovoltaic (PV) system and home battery storage with the goals of maximizing the self-consumption of energy and minimizing the electricity bill. The results of the simulations show that while the goal of the home battery was to absorb the generated PV power and use it to later supply the demands of the household, thus limiting voltage rise and reverse power flows to the grid, in practise the opposite occurred. Triggered by electricity prices, the simultaneous battery charging in winter and simultaneous discharging in summer, even though for shorter periods, resulted in more severe overloading and power reversal than when no batteries were used.