Development of test-bed system for hybrid distribution transformers using controller hardware-in-the-loop simulation

The recent increase in inverter-based resources (IBR) in power grids has led to active research to ensure reliable grid operation and power quality. Hybrid distribution transformers (HDTs) integrate conventional transformers and power electronic converters to provide high reliability and cost-effectiveness while maintaining good power quality. However, to effectively utilize HDTs in real power systems, it is essential to validate that the fault-response algorithms operate reliably under severe grid incidents and unstable conditions. To address these issues, this paper presents a controller-hardware-in-the-loop (CHIL) simulation test-bed that can test grid incidents and validate the protection algorithm of the HDT. The proposed algorithm ensures stable HDT operations through real-time fault detection and reaction, protecting the converter side of the HDT, as verified using the CHIL simulation test-bed. A 5 kW HDT test-bed is developed using an OP5707 real-time simulator. The validated CHIL test-bed and the protection strategy establish a practical framework for deploying HDTs in distribution networks, enabling reliable operation and effective fault coordination in grid applications.