An Exponential Droop Control Strategy for Distributed Energy Storage Systems Integrated With Photovoltaics

The integration of photovoltaics (PVs) in low-voltage (LV) grids is expected to rise within the following years posing technical challenges to the reliable operation of the electrical system. To tackle these challenges, distributed energy storage systems (ESSs) coupled with PVs at prosumer side arise as a promising solution. Therefore, during the last years several control schemes have been developed to manage ESSs. To overcome disadvantages of conventional control strategies, a new localized control strategy is proposed in this paper. The proposed control aims to improve voltage profile along distribution feeders, by mitigating the peaks of the net injected/absorbed power at prosumers' point of common coupling. Additionally, the new control aims to maximize prosumers' self-consumption. To achieve peak mitigation at the net power profile, an exponential droop is introduced that charges/discharges ESSs with different rates based on the residual power between PV generation and load demand. Using this droop, ESS charging/discharging power is exponentially increased as the residual power becomes greater. To maximize the self-consumption of the installation, an optimization procedure is developed that properly adjusts the exponential droop parameters to prosumer's generation and consumption profile. The effectiveness of the control strategy is validated by both simulation and experimental results.