Frequency Support Strategy for Fast Response Energy Storage Systems

Power systems are facing the displacement of conventional power plants by converter-interfaced generation, which does not inherently provide inertia; as a result, large frequency deviations can occur after a power imbalance, compromising the frequency stability. Energy storage systems (ESSs) are becoming key elements in improving the performance of both the electrical grid and renewable generation systems. They are able to store and release energy with a fast response time, thus participating in short-term frequency control. This letter proposes a strategy to minimize the frequency nadir in the event of a frequency disturbance using the energy stored in ESSs. An analytical procedure is presented to determine the optimal time to inject ESS power into the grid after a power imbalance. Different parameter scenarios and injected power waveforms are discussed.