Transformer protection based on dynamic state estimation

Abstract

The objective of the proposed research is to detect transformer internal faults or transformer overheating and trip the transformer, with immunity to external faults for which tripping of the transformer is not required. A new transformer protection scheme based on dynamic state estimation has been proposed. Specifically, the proposed scheme continuously monitors transformer terminal voltages and currents and other measurable quantities such as tap settings, temperatures, etc. The measurement data are utilized in a dynamic state estimator of the transformer protection zone. The dynamic state estimation simply determines how well the measured data fit the dynamic model of the transformer. When the fit is within the accuracy of the meters by which the measurements are taking, the dynamic state estimator provides the true operating condition of the transformer. Discrepancies indicate an internal abnormality. The scheme takes decisions based on the operating conditions of the transformer. This scheme does not require any coordination with other protection functions. Several protection gaps, such as the coordination and settings of relays, have been resolved with proposed new method. The proposed method is secure, reliable, more sensitive and faster than legacy protection functions. The applications of the proposed protection method for future research are discussed.