Frequency Response Capabilities of Utility-scale Battery Energy Storage Systems, with Application to the August 2018 Separation Event in Australia

Abstract

This paper is aimed to investigate the capabilities of utility-scale energy storage system (BESS) in provision of both contingency and regulation frequency control ancillary services (FCAS). In particular, the fast mode-change capability of battery and its corresponding impacts on its frequency support ability is investigated through dynamic modelling of the 100 MW Hornsdale battery during the August 2018 separation events in Australia. In this regard, a converter-based battery dynamic model is presented which includes current- bidirectional DC-DC converter, thereby being able to observe its fast mode change as a response to severe frequency excursions. Also, an active power-frequency characteristic is proposed which considers the impact of battery pre-contingency operating point on its available headroom for primary frequency response provision. Moreover, an active power reference generation strategy is suggested which takes into account regulation FCAS provision through automatic generation control (AGC) as well as contingency FCAS provision through droop controller. Finally, it will be shown how BESS installed in Victoria might have potentially prevented the severity of the August 2018 event by prevention of both under-frequency load shedding (UFLS) and secondary photovoltaic (PV) trip.