A real-time calculation method of circulation for Y/Δ transformer

Y/Δ transformer is widely used in power system and the circulation is difficult to measure accurately. This paper mainly discusses how to use the sample data to calculate the circulation of Y/Δ transformer. The method is deduced by the basic equations of transformer and the relationship of transformer currents. It uses numerical integration and trapezoid method to disperse the middle variables and then obtain the result of circulation. The result of the calculation is in time value, the accuracy is improved by the sample frequency. Simulation shows the accuracy of the circulation. This calculation can be used in parameter calculation and transformer protection.