Study on transformer winding deformation using low-voltage impedance diagnostic method

The short-circuit damage of a power transformer is the serious main equipment accident in power grid. Thus to reduce transformer short-circuit accident by detecting transformer winding deformation is extremely important. This paper proposes a methodology to interpret low-voltage impedance measurements of a deformed or undeformed transformer winding. To achieve that, geometrical structures and leakage flux distribution of a power transformer winding is analyzed by analytical method, a mathematical model for the relative position of the transformer winding and short-circuit impedance is built, and then the diagnostic principle and criteria for winding deformation based on low-voltage impedance method is demonstrated in this study. In the end, a case study and some routine tests further verify the validity and accuracy of this diagnostic method.