Transformer Energization Using Grid Forming Converter

Increasing renewable integration is posing new challenges to reliability of power networks. One of these challenges is to restart the power network and energize power transformers in the event of a blackout. Grid forming converters can provide a potential solution to this issue because they can be controlled as independent, self starting, voltage sources. This study analyzes and compares four grid forming controllers to assess their capabilities to energizing the transformer. Simulations are performed with common parameters with different line lengths and transformer sizes. The results demonstrate that the inrush current and voltage show similar trends for these four controllers but with different magnitudes. The highest magnitude is observed for the matching control while other control schemes demonstrated similar performance. Moreover, each controller show different harmonic response and it is important to consider resonant frequencies of the network.