Dynamic Active and Reactive Power Control with Utility-Scale Battery Energy Storage Systems

In this paper, a control algorithm is presented which provides a charge/discharge power output with respect to changes in the grid frequency and the ramp-rate limits imposed by the Turkish Electricity Transmission Corporation (TEIAS), whilst managing the Battery Energy Storage System’s (BESS) State-of-charge (SOC) to maximize the use of the available energy capacity. A new control algorithm is developed to provide coordinated reactive power support along with grid frequency support, which is one of the grid balancing services provided by grid-tied BESS, to ensure flexibility and reliability in electricity networks. The algorithm is evaluated in a Simulink-based system model, which includes a transmission line model with a bi-directional model predicted controlled voltage source converter connected to the BESS. The model initially detects frequency and voltage fluctuations relative to reference values, and reference currents are then generated via an energy management algorithm based on the magnitude of fluctuations and the battery state of charge. Furthermore, switching signals for the inverter are determined with model predictive control. Simulations are conducted using one-day frequency data and by connecting or disconnect the loads randomly that cause the voltage drop/increases. The voltage fluctuations obtained from the model have demonstrated that both active and reactive power references are provided by the 2MW/1MWh BESS system successfully.