Mitigating voltage deviations in a residential distribution grid using predictive control of community battery storage system

The increasing adoption of Distributed Energy Resources (DERs), including solar photovoltaic (PV) systems and behind-the-meter battery Systems (BTM batteries), has introduced new challenges for Distribution Network Service Providers (DNSPs) in maintaining power reliability. Low voltage (LV) distribution grids with a mix of PV, BTM batteries, and EVs are constantly experiencing power quality issues due to the intermittent nature of renewable energy sources such as rooftop PV. However, managing these power quality issues, such as voltage fluctuations, remains a critical challenge. This research focuses on real-time control of a community Battery Energy Storage System (BESS) to mitigate voltage deviations resulting from rooftop solar PV's intermittency and generation surplus. A Model Predictive Control (MPC) system is proposed to control the community BESS intelligently. This thesis addresses two research questions; How does the MPC strategy regulate the community BESS's charging and discharging rates to mitigate voltage fluctuations in the network? And What is the minimum size of the community BESS needed for adequate control? The ideal placement of the BESS along the feeder will also be determined. Furthermore, the identified research gaps indicate the need for further investigations into optimal battery sizing and using complex weather conditions for simulations which is out of the scope of this research. Here, the simulations are conducted on an LV residential radial network with fourteen households to evaluate the performance of the MPC-controlled BESS located at the beginning or end of the feeder. The simulation results demonstrate that the proposed MPC controller effectively reduces voltage deviations in the LV residential grid compared to a fixed charging schedule. Notably, the MPC-controlled BESS placed at the end of the distribution feeder exhibits the lowest cumulative voltage error (the best performance). Conversely, applying a fixed charging schedule to a BESS placed at the end of the feeder results in the highest cumulative voltage error (the worst performance). Additionally, the research proposes a minimum size for the community BESS required to implement the MPC. Extensive simulations reveal that the minimum battery size depends on the desired level of voltage deviation that grid operators are willing to accept. In the case of the studied LV residential grid, the minimum battery size that can be used to mitigate the voltage fluctuations while adhering to all the constraints is 43 kWh, with a maximum charging/discharging rate of 10 kW, allowing for a voltage deviation of only 240 ± 6.7 V. These results suggest DNSPs choose the size of the battery based on their desired level of voltage deviation.<p></p>