Grid-forming battery energy storage systems (GFM-BESS) have been identified as pivotal technologies for increasing grid strength and enabling black start, given their capacity for autonomously establishing voltage and frequency. The present study investigates the black start capability and fault response of GFM-BESS in a Wind-BESS hybrid plant, conducting multi-scenario site tests to provide practical insights for its large-scale application in modern power systems.

The research is divided into three phases: The soft start-up capability of the GFM-BESS within the 35kV bus is validated in Phase I. The voltage build-up is achieved within 10 seconds, with steady-state voltage stabilized at 1.06–1.08p.u. and frequency deviation confined to ±0.2Hz, demonstrating rapid voltage restoration. Phase II extends to plant-level black start and load operation. The findings indicate that the fully deployed GFM-BESS maintains bus voltage at 0.9–1.0p.u., with transient voltage peaks ≤1.35p.u. during main transformer switching or 220kV transmission line energisation. The transient durations of these peaks, which are no more than 7 milliseconds, indicate the robustness of the isolated system when confronted with complex disturbances. Phase III is centred on the execution of artificial short-circuit test. In the context of a 250-millisecond three-phase short circuit, the BESS terminal voltage undergoes a reduction to 0.3 p.u., accompanied by a peak fault current of 2.97 p.u. It is noteworthy that the post-fault recovery process is characterised by its swiftness and efficacy.

The findings emphasise superior voltage/frequency regulation and transient stability of GFM-BESS across black start, load energisation, and fault scenarios. These capabilities offer critical references for enhancing grid resilience in high IBR penetration systems.