A new hybrid simulation integrating transient-state and steady-state models for the analysis of reversible DC traction power systems

This paper presents a new hybrid simulation method for reversible traction power supply systems (RTPSSs) supplied by four-quadrant converters (4QC). RTPSSs overcome several drawbacks of conventional DC electrification systems, such as wasting of braking energy, output voltage fluctuation, and low power factor at light load conditions. The paper introduces the system topology of a RTPSS and illustrates its advantages over standard DC systems. A hybrid simulation method is proposed to study the performance of the RTPSS taking into account the dynamics of multiple trains. This hybrid simulation integrates train motion, steady-state and transient-state models, and is able to evaluate both the system-level steady-state performance (voltage, current, power and energy) and the equipment-level transient-state performance (harmonics, ripple, power factor and stability). Structure and signals flow of this hybrid simulation system have been introduced, and the methodology of modeling has been presented. The validity and applicability of the proposed hybrid simulation method have been proved by a case study of a 10 km railway line with 6 substations. To date, no other work has accomplished the steady-state and transient-state study using a single integrated simulation.