BESS Primary Frequency Control Strategies for the West Africa Power Pool

In recent years, power systems have been moving from conventional power plants toward the integration of renewable energy sources (RES). This trend is taking shape in many developing economies, including in the West Africa Power Pool (WAPP). The integration of RES, however, stresses grid security and stability due to the variability and intermittency of the underlying renewable sources. Battery Energy Storage Systems (BESS) have been identified as a possible solution to address the frequency control challenges in the WAPP Interconnected Transmission System (WAPPITS) in order to help to accommodate high levels of RES. This paper analyzes the application and effectiveness of BESS in providing primary frequency control reserves in the WAPPITS. The analyses are based on numerical simulations that were performed using an open-loop model based on historic frequency measurements from the WAPPITS. The simplified model provided a first-order analysis of the frequency control and state of charge (SOC) restoration logic for BESS installations. This study indicates that a droop-based control strategy that is able to react only to the symmetrical and fast frequency oscillations in the network could be appropriate for regulating BESS in the system. Moreover, it demonstrates that the deployment of BESS alone does not solve frequency control problems and a deep revision of the frequency control service is required, mainly involving traditional power plants.