Single-Tuned Harmonic Passive Filter Design for AC Electric Railway Traction Power Substation

This paper focuses on the design of single-tuned passive harmonic filters to mitigate harmonics found in the load current of an AC railway system. This system is modelled in MATLAB/Simulink as a 50Hz 25kV TPSS connected to an ETS train which acts as the load. The train's load profile is generated based on an energy consumption model which simulates the train stopping at a station and then departing. FFT analysis is performed on the load current to determine the harmonic magnitudes while at the same time the THD and TDD of the load current is calculated. The simulation results show that all these values exceed the threshold values set by the standard IEEE-519. Therefore, single-tuned passive harmonic filters are designed each for the 3rd, 5th, 7th, 9th, and 11th harmonic to mitigate the respective harmonic at a low cost. These filter's reactive power and quality factor are used to determine the filter's RLC parameters. The Bode plot of each filter is also generated and analyzed. After the filters are added to the model, results show that all harmonic magnitudes are reduced to less than 4% whereas TDD is reduced to less than 5%, which successfully meets below the limit set by IEEE-519.