Extraction of Inertial and Droop Response from Utility Scale Battery Pack at the State of Charging

Abstract

In weak grids, high penetration of renewable energy sources (RES) poses a major threat to the overall system stability and reliability. Absence/lack of rotational inertia worsens stability issues like frequency support in case of a disturbance. After the loss of a generating unit, fast-acting battery energy storage system (BESS) can emulate the role of the lost generator by providing the dynamic frequency support until, corrective actions are taken to restore the frequency. Unlike others, this work focuses mainly to make the BESS emulate a real generator, providing inertial and droop response at its charging state. To achieve the objective, a modification in battery charge control algorithm has been introduced. It ensures the provision of ancillary services free of cost and exclusion of any additional wear and tear on the BESS. As a test case, a customized model of a small microgrid has been used and the effect of droop and inertial response from the BESS on system's transient response, has been investigated using time domain simulations in PSCAD/EMTDC.