Short-Term Voltage Stability Improvement via Dynamic Voltage Support Capability of ESS Devices

Abstract

Modern power systems are undergoing a steady increase in the loading level and higher penetration of renewables. Induction motor (IM) loads and fixed-speed induction generator (FSIG) based wind turbines (WTs) are broadly used in many power systems. Both IMs and FSIGs draw high amounts of reactive power during large disturbances, which pose major problems for short-term voltage stability (ST-VS). In this paper, the effects of IMs, FSIG-based WTs, and over-excitation limiter (OEL) of synchronous generators on ST-VS are analyzed and illustrated. Then, the use of energy storage systems (ESSs) to provide dynamic voltage support (DVS) to power system during and after large disturbances is investigated, as a countermeasure against short-term voltage instability. To implement ESS's DVS capability, the required power injection by the ESS is dynamically determined and then tracked after the occurrence of a disturbance. The effects of implementing fault ride through and time-overload capabilities of ESS's inverter, on ST-VS of the system, are also analyzed. Optimal power factor adjustment for power injection by ESS, from an ST-VS viewpoint, is discussed as well. It is shown that the DVS capability of an ESS can be effectively used against detrimental effects of IMs, FSIGs, and OELs on ST-VS.