A New Approach for Phase Loss Detection and Protection in Ynd Transformers Primary Using Backup Interface Systems

This paper presents a new method for detecting phase loss in Ynd transformers by integrating a Backup Interface Unit (BUI). Traditional detection techniques often struggle to reliably distinguish between genuine phase loss events and current imbalances caused by load variations, harmonics, or asymmetrical operating conditions, which can lead to delayed response or false triggering. The proposed method combines Clarke and Park transformations with controlled off-grid transition tests to enhance fault identification and validation. By applying these techniques, the system achieves higher sensitivity to true phase loss while maintaining robustness against normal operating disturbances. Simulation and laboratory experimental results confirm improved detection accuracy, reduced false positives, and faster protection response compared to conventional approaches. In addition, the method ensures continued operation and voltage stability during faults, which is critical for maintaining power quality and equipment safety. These advantages make the approach highly suitable for modern industrial facilities and smart grid applications where reliability and resilience are key requirements.