Modular Hybrid Transformers Toward Grid Resilience: Efficiency Analysis and Operation

This article proposes modular hybrid transformer architectures to improve grid resilience. The conventional line-frequency transformer is augmented with a partially rated power electronics converter to realize a hybrid transformer system. The proposed modular approach is envisioned to replace a single large power low-frequency transformer with multiple smaller rated hybrid transformer systems during disasters and emergencies. A hybrid transformer system enables controlled current sharing between the modular system. The efficiency analysis and operational aspects of a modular hybrid transformer architecture are thoroughly discussed in this article. The proposed efficiency analysis combines empirical data and numerical analysis of the overall modular hybrid transformer system. The optimum current sharing ratio to achieve maximum efficiency operation is presented for the proposed architectures. One of the proposed architectures (Configuration B) also offers load voltage regulation in case of grid voltage sag/swell occurrence. The proposed concept and analyses are experimentally validated through a scaled-down hardware prototype. The total ownership cost of the proposed system is also presented to emphasize the potential cost-benefits. Supplementary video files accompany this article to showcase the extensive experimental validation cases.