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All Journal International Journal of Power Electronics and Drive Systems (IJPEDS)
Chuen Ling Toh
Universiti Tenaga Nasional
Control & Systems Engineering Electrical & Electronics Engineering

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Design a nine-level modular multilevel converter for DC railway electrification system Chuen Ling Toh; P. C. Ooi
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 11, No 1: March 2020
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (534.096 KB) | DOI: 10.11591/ijpeds.v11.i1.pp151-159

Abstract

A recuperating converter is highly demanded in traction power substation to deliver the braking energy generated by a traction vehicle. Conventional voltage source inverter had been implemented in the traction power station. However, large ac line filters must be installed to improve the quality of ac voltages and currents. This paper proposes to install a nine-level Modular Multilevel Converter (MMC) as a recuperating converter. The main aim is to eliminate the need of ac line filters while producing good quality of ac voltage and current waveforms. The MMC is designed and modelled using MATLAB/Simulink Simulation tool. A centralized control of balancing all the sub-module capacitor voltage level is proposed with Third Harmonic Voltage Injection Level Shifted Pulse Width Modulation (THVI-LSPWM) technique. The simulation results prove that with the application of MMC, good quality of ac voltages and currents are being produced. The Total Harmonic Distortion indexes are found less than 3.5 % without using any ac line filters in the system. In addition, the classic DC link capacitance has also being eliminated. 
DC traction power substation using eighteen-pulse rectifier transformer system Chuen Ling Toh; Chee Wei Tan
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 12, No 4: December 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijpeds.v12.i4.pp2284-2294

Abstract

Twelve-pulse rectification system had been widely integrated in today’s DC traction power sub-station (DC-TPSS). This configuration had successfully mitigated low order harmonic distortion. As some research findings had confirmed that the dc voltage and current ripple factors may further minimize by increasing the number of rectification pulses to 18, 24, or 36. This paper had presented a simulation study to investigate the prospect of implementing an eighteen-pulse rectification system in a DC-TPSS. The theory of phase-shifting transformer used to produce an 18-pulse rectifier is presented with simulation verification. Simulation result shows that 3.69% of grid current distortion index is recorded without installing any filters. In addition, the dc voltage and current ripple may also be further reduced for about 30% compared to a conventional twelve-pulse rectification system.
LCL-filter design and analysis for PWM recuperating system used in DC traction power substation Najwatul Alisa Sabran; Chuen Ling Toh; Chee Wei Tan
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 13, No 4: December 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijpeds.v13.i4.pp2244-2254

Abstract

Voltage source inverter (VSI) had been used in dc traction power substation to deliver the trains braking energy back to the utility grid. To mitigate low order harmonics components, pulse-width-modulation (PWM) technique is commonly used in VSI controlled. As a result, the ac voltage and current waveforms may contain high frequency ripples. This paper proposes to mitigate the high frequency harmonics using LCL-filter with series R-damper. This filter offers good attenuation on harmonics with smaller size compare to other passive filter topologies. Theoretical analysis and simulation verification are conducted in designing the proposed filter. System level simulation had also been carried out. Sinusoidal grid current and voltage waveforms are recorded (THD<2%). This paper also includes damping losses analysis in conjunction with resonance peak suppression in designing the R-damper.
Co-Authors Chee Wei Tan Najwatul Alisa Sabran P. C. Ooi