Research on Novel Active Power Quality Comprehensive Compensation Technology Used in Electrified Railway in China

In order to solve the power quality problems caused by traction load of the single-phase 25 kV AC traction power supply system (TPSS), such as the three-phase voltage unbalance, harmonic distortion and low power factor, some power quality comprehensive compensation technologies have been studied in China recently. In this paper, a novel traction power supply system is discussed, which adopts the Scott connection balanced transformer and the active power flow controller (PFC). The equivalent mathematical model of the system is derived using the theory of electrical transformation and algorithm of comprehensive compensation. Moreover, the topology and control method of PFC are presented. Finally, the simulation model is built, the effectiveness of the proposed system is verified and the validity of the control algorithm is demonstrated by the case studies.