Establishment and Application of Online Detection Method for Load Loss of Dyn11 Type Distribution Transformers

The load loss value of distribution transformers not only determines their economic operation level but also affects their temperature rise and electrical insulation performance. Traditional offline tests during power outages fail to accurately reflect the power loss of equipment under actual operating conditions. To monitor the operational status of distribution transformer windings in real-time and enhance the equipment's ability to prevent and respond to failures, it is necessary to study online detection and fault diagnosis methods for winding losses. The paper uses a Dyn11-type 10kV distribution transformer as an example to calculate the equivalent resistance of each phase winding, thereby obtaining real-time load loss values during operation. The proposed online detection method is validated through comparisons with modeling simulation tests and offline detection data. Results indicate that this method can accurately detect the equivalent resistance of distribution transformers, with a discrepancy of less than 2% compared to offline test data, enabling online detection of winding load losses and facilitating the diagnosis of transformer winding status during operation.