Optimising power grids using batteries and fuzzy control of photovoltaic generation

Germany's energy turnaround is leading towards an increasing integration of photovoltaics throughout its distribution grid. As solar power generation fluctuates greatly, distribution system operators are faced with the challenge of preventing grid component overload and voltage range violations. One solution might be to integrate battery storage systems into private households and reduce active peak power at the grid connection point. Since peak shaving is often impossible with the conventional operating strategy of the storage system, solar plants must sometimes be throttled back. In this study, a fuzzy control system is introduced that reduces peak feed-in and thus also energy losses due to throttling back solar power. The system uses solar surplus and battery charge level as input parameters, and standardises them to ensure easy adjustment to different combinations of plant size and storage capacity. Load flows for a complete year were modelled using real-world measurement data, which showed that even small electrical storage capacities (<5 kWh) reduce energy losses considerably and produce only small losses in self-consumption. Thus, there is an economic benefit for plant operators which switch from a conventional to a grid-optimised operating strategy.