The application and analysis on three different current compensation methods used in transformer differential protection

This paper analyzes used in wye-delta connected transformer differential protections, impacts of these current compensation methods to identify inrush current under different conditions of occurring inrush, i.e. single phase, two phases and three phases, are studied. Based on the simulation of MATLAB, this paper emphasizes the second harmonic component contained in differential current when transformer is energized without loads, and concludes that the compensation methods only using currents in wye side of transformer has the same effect to discriminate inrush currents compared with other two compensation methods. In addition, It analyses the relationship between the first and second harmonic components contained in the differential current, and points out that the method using phase angle in the second harmonic component in differential current is not suitable for three different current compensation methods.