9th International Renewable Energy Storage Conference (IRES 2015)
The increase of renewable energy penetration in the distribution grid creates a problem concerning the power quality. One of the most critical scenarios occurs in times of excessive power generation combined with low load consumption, which may lead to an overvoltage due to reverse power flows. Grid expansion is often used as a solution to reduce the voltage rise. However as this new cables or transformers are only used a few hours per year, energy storage might be used as a voltage support among other alternatives. This research is embedded in the project SmartPower- Flow1, which deals with the optimization of grid expansion versus energy storage at low voltage levels, where the grid expansion results due to increasing renewable power flows. Since both community and residential batteries have their own control and are connected to the same grid, the interaction between these battery systems has to be studied. This study focuses on residential batteries. Current control strategies for residential photovoltaic (PV) storage systems do not efficiently use the battery as a grid voltage support. Therefore, an investigation on the more intelligent control strategy has been conducted. The objective of the study is to determine the best control strategy for residential PV storage systems in Germany based on technical and economic perspectives. The strategy should be able to control the voltage at the point of common coupling (PCC) while still exhibiting a high selfconsumption rate (SCR). Finally a qualitative evaluation of the strategies in respect of the SCR, the self-supply ratio (SSR), the curtailment losses rate (CLR) and the ability to limit the peak voltage at the point of common coupling (PVR) is presented.