A comprehensive control strategy of railway power quality compensator for AC traction power supply systems

The development of electrical railway systems leads to critical power quality problems in the power grid. This paper discusses a kind of half-bridge-based railway power quality compensator system (HBRPQC) that can compensate negative sequence currents, harmonics, and reactive power simultaneously. In order to keep the HBRPQC performance efficient for the different kinds of transformers used in traction power supply substations, a new multifunctional control strategy that performs better than previous methods is proposed. Due to the fast dynamicity of traction loads, a recessive self-tuning PI controller based on fuzzy logic is adopted in the current control system. The output control variables are integrated with carrier-based pulse width modulation techniques to generate the pulse signals of HBRPQC switches. The performance of the proposed control strategy is verified for V/V, Yd11, and Scott transformers by simulation and the results prove the effectiveness of the strategy.