Power Quality Improvements in Traction Power Supply System

Lee, Jun Sheng (2022) Power Quality Improvements in Traction Power Supply System. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

As traction railway system is widely used worldwide, its stability and performance need to be ensured by investigate issue occurring in the traction power supply system (TPSS). The paper reviewed the harmonic issues that frequently occurs in TPSS. Low Frequency Oscillation (LFO) issue is chosen to be the focus of this research. During LFO, the input line voltage and current of the traction network experienced oscillation and fluctuation. Thus, the objectives of the research are analysing the LFO by investigating its influential factors, and design the approaches to mitigate the impacts LFO. After investigation, the influence factors have been marked which are the number of trains and catenary length. Thus, an advance converter’s control technique, DQ current control (DQCC) is adopted. The performance is then verified by comparing to conventional method, transient current control (TCC). By using DQCC, the overshoot and fluctuation of DC-link voltage reduced by 98.77% and 80% respectively, and the THD of input current have reduced by 58.73%. The THD of the grid voltage and current reduced by 49.84% and 25.68% respectively. This showed that the DQCC strengthen the dynamic performance of the grid-train network thus increase the stability of the TPSS. With that, the analysis results verified the performance of the DQCC, and it can replace the conventional TCC to be the control techniques of the 4QC to mitigate the LFO effect.