Research on the harmonic in new continuous cable traction power supply system and its transmission characteristic

This study does research on resonance and harmonic transmission problems in a new continuous cable traction power supply system (CCTPSS), CCTPSS can realise long-distance co-phase power supply and effectively reduce phase separation and is applicable for extended power supply in areas with the weak power grid. Firstly, the system structure is introduced, a cable traction network is divided into three kinds of subnets for its complicated topology and huge system scale. The equivalent circuit model and mathematical model of each subnet are established with distribution parameters, especially the cable capacitance effect be considered. Then, according to the two-port network analysis theory, the system equivalent circuit is constructed by considering the electrical connection relationship, system harmonic impedance expression is calculated. Resonance influence factors and harmonic transmission mechanisms are analysed. Finally, theoretical analysis validity is verified in simulation; harmonic transmission characteristics CCTPSS including traction cable and overhead catenary, are studied. The new system shows better resonance performance compared with the existing AT traction power supply system.