Comparative Analysis of Grid-Forming Control of Energy Storage Systems for Black - Start

Large-scale integration of renewable energy sources (RES) with power electronics is challenging the stability of the power system. This has increased the risk of wide-area blackouts. Thus, the changing electricity generation profile in the power system necessitates the use of energy storage (ES) systems to provide black-start services. However, this requires the grid-forming (GFM) control of ES systems rather than the traditionally prevalent current control architecture. With the above, this paper benchmarks the droop control and virtual synchronous generator (VSG) control for ES systems in the GFM mode for black-start. The performances at different stages during the black-start are analyzed and compared. Specifically, dynamics during transformer energization, load pick-up, and connection to the equivalent grid have been compared to highlight the pros and cons of each strategy. Simulations and hardware-in-the-Ioop experimental tests are provided to validate the analysis.