Researchers from The Hong Kong Polytechnic University assessed the causes of overvoltage in pantograph arcing and devised an approach to overcome it
High speed, large transportation volume, high efficiency, and low pollution are some of the characteristics of high-speed railway (HSR). The pantograph/catenary system is a major component in the traction system and a passage through which the train draws power from the power system. The most common type of pantograph today is the half-pantograph, which offers a more compact and responsive single-arm design at high speeds. However, pantograph arcing can have an impact on the performance of the catenary system, which can reduce the operational life of the pantograph. The resulting high voltage difference and current surge can impair the train or the regional power system.
Now, a team of researchers from Department of Electrical Engineering, The Hong Kong Polytechnic University assessed the possibilities to protect the main electrical equipment of the traction drive system including the transformer and the back-end converters from effects of pantograph arcing. The team assessed the causes of overvoltage in pantograph arcing and devised an approach to overcome it. The team built an energy recycling system using multiple supercapacitor-based energy balancing subsystems that were capable of withstanding the high voltage and current. To absorb the inductive energy from arcing, the team used bidirectional converters and a supercapacitor system.
The proposed method can be installed at the primary side of the transformer and can control the charging–discharging status of the supercapacitor system and recycle the inductive energy of the transformer. The simulation circuit implemented by Matlab Simulink validated the effectiveness and feasibility of the proposed system. The supercapacitor system can also be used to offer energy for locomotive sensors or other devices and can also provide instantaneous power compensation to overcome the voltage fluctuation of the traction power supply and recycle the braking energy. Although the method is economically costly, the economic cost is more acceptable than resultant safety costs considering the insulation damage and safety issues of pantograph arcing. The research was published in the journal MDPI Energies on March 28, 2019.
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