Sustainability assessment of novel transformer technologies in distribution grid applications

Abstract

Abstract As more renewable energy sources are integrated in the distribution grid, congestions might arise due to voltage band violations or overloaded grid components. Novel transformer technologies have the potential to extend the otherwise limited grid capacity without necessitating extensive grid enforcements. A comparative sustainability analysis is provided covering generic transformer technologies such as state-of-the-art line-frequency transformers, transformers equipped with on-load tap changers, entirely power electronic based solid-state transformers, and hybrid transformers. An accurate and realistic system environment is modeled based on real grid topologies combined with yearly measurement data. The life-cycle assessment shows that the conventional line-frequency transformer is most eco-friendly. However, if the transformer’s ability to extend the grid’s capacity for integrating renewable energy sources is considered, a negative environmental impact can be compensated. We recommend hybrid transformers as future replacements of conventional line-frequency transformers in situations where grid congestions arise in the course of implementing the goals of the Swiss Energy Strategy 2050. Hybrid transformers are capable of enhancing the grid capacities on both, medium- and low-voltage level, while being highly eco-friendly at the same time.