Study on Harmonic Detection Methods In Traction Power Supply System

In this paper, two methods based on fast Fourier transform (FFT) and instantaneous reactive power theory are compared in order to detect the harmonic current of traction power supply system. Both theory analysis and simulation results indicate that they can detect the harmonic current of traction power supply system precisely and real-time. FFT can detect the separate amplitude and angle of any order harmonics while it is not prefect in real time. The method based on instantaneous reactive power theory can detect harmonic component in real time while the detect results contain the whole information of amplitude and angle which can not be separated. This method also needs proper cut-off frequency to meet the measurement precision and dynamic response speed. Considering both measurement precision and real-time, the method based on instantaneous reactive power theory is better.