Towards A Full Automatizated Ultrafast Blackstart Through Inverter-Based Generation

This paper describes a fast black start strategy for the Swiss railways electrical grid that speeds up the recovery by means of automatisation and the use of inverter-based resources. First, a concept for black start relying on a soft energization of a backbone structure is described. The energization is carried out with a grid-forming unit due to its flexibility and controllability, despite its limited power ratings in comparison with conventional power plants. Second, the grid model including generation plants, transformers and loads are defined for both RMS and EMT studies and validated against field measurements. Furthermore, a framework has been developed that facilitates the study of different blackstart methodologies, including adequate switching sequence and admissible ramp rates for loads. The black start concept is validated both via thorough simulations and through field tests, covering each step of the process and analysing possible overvoltages, inrush currents, frequency behaviour and adequate power distribution among plants and lines.