Re-energization of a power system with a distribution network

The evolving energy mix increasingly integrates variable renewable energy systems into power grids, prompting the exploration of alternative black-start approaches at the distribution network. This study focuses on the use of distributed resources connected via power electronics converters to supply loads at the distribution level through transformers, following a blackout of the transmission system. Energizing transformers generates high unbalanced inrush currents with harmonics due to iron core saturation, posing a significant challenge. Unlike synchronous machines, power electronic converters cannot support large inrush currents. This paper demonstrates a grid-forming control that provides high-quality voltage while protecting the converter by limiting the inrush current. A benchmark is then implemented to illustrate the use of grid-forming to energize multiple transformers during a distributed black-start. It also demonstrates the ability of the proposed grid-forming to synchronize with an existing grid.