Design of Single-Tuned Harmonic Passive Filters for DC Electric Railway Traction Power Supply System

The development of the electric railway system in Malaysia is growing rapidly since 1995. The use of a twelve-pulse rectifier to convert AC to DC supply in TPSS will generate the 11^th and 13^th harmonic current to the distribution lines. In this paper, a DC urban electric railway system is modeled and its harmonic analysis is discussed. It was found that the harmonic current distortion caused by the TPSS has exceeded the TDD and IHDi limits based on IEEE 519–2014 standard. Thus, the harmonic filter is chosen to mitigate this harmonic problem. The single-tuned harmonic passive filters are designed as they are more cost-effective, simple to design, and have high flexibility. The three-dimensional perspective of impedance, quality factor, and reactive power is analyzed to reduce the harmonic, improve the power factor, and prevent interharmonics at a low cost. The reactive power and quality factor selected based on the three-dimensional perspective are used to determine the capacitance, inductance, and resistance of the single-tuned harmonic passive filter. In addition, the graph of impedance against harmonic order and the bode diagram are plotted to analyze the characteristics of the filters. The results show that the designed filters can reduce the TDD to 1.97% and below. Besides, the 11^th IHDi is reduced to 1.94% and below while the 13^th IHDi is reduced to 1.97% and below. Therefore, the harmonic current distortion is complying with the IEEE 519-2014 standard limits with the presented single-tuned harmonic passive filters.