Reactive Power Injection from Battery Energy Storage During Voltage Dips at a Thermal Power Plant

Battery energy storage systems (BESS) are being deployed to provide a range of power system services. In this paper, the voltage support capabilities of a 10 MVA, 5 MWh BESS installed at a thermal power plant are explored. The study specifically relates to the voltage dips caused by starting of large boiler feed pump motors on the 11 kV supply of the power plant. The benefits of reactive power injection from BESS are explored via simulation and validation is provided from tests on the actual plant. The likely reduction in voltage dip if the BESS can contribute its rated reactive current is quantified. As a result, the motors experience higher starting torque and peak current, however as they start more quickly, the contribution to heating is expected to reduce. The effect on provision of other services demanded from the BESS and wider opportunities to provide voltage support are discussed.