Comparative Evaluation of Black Start Capabilities in Synchronous and Asynchronous Generators for Enhancing Grid Resilience

ABSTRACT Power system resilience relies heavily on the ability to recover from widespread blackouts through black start procedures. Traditionally, synchronous generators, such as hydroelectric and gas turbines, have been the backbone of black starts due to their inherent inertia, voltage control capabilities, and proven operational record. However, the global shift towards renewable-dominated, low-inertia grids has introduced asynchronous resources, including inverter-based wind, solar, and battery energy storage systems, into restoration planning. This chapter compares synchronous and asynchronous generators in the context of black start, highlighting their strengths, limitations, and complementarities. Synchronous units remain crucial as stability anchors but face growing challenges from ageing infrastructure, fuel and cooling dependencies, and geographic constraints. In contrast, asynchronous resources offer rapid deployment, modularity, and distributed restoration potential; however, they require advanced control strategies, regulatory adaptation, and robust cybersecurity safeguards. Case studies from the UK, Texas (ERCOT), Japan, Europe, and island systems, such as La Palma, illustrate the challenges of relying on legacy approaches and the opportunities offered by emerging technologies. The findings emphasise the importance of hybrid black start frameworks that integrate synchronous reliability with asynchronous speed and flexibility. Such approaches will be key to ensuring fast, stable, and resilient system restoration in renewable-dominated power systems of the future. Keywords: Black Start Capability, Synchronous Generators, Asynchronous Generators, Inverter-Based Resources IBRs), Grid Resilience, Hybrid Restoration Strategies