The dual-loop control strategy of railway static power regulator for V/V electric traction system

A kind of RPC (Railway Static Power Conditioner) was discussed to govern power quality in V/V electric traction system of the high-speed railway at 350Km/h, which is used to carry out the comprehensive compensation of negative sequence, reactive power and harmonic currents in the traction substation. The paper analyzed the negative sequence compensation principle, and a dual-loop control strategy was proposed for RPC. A set of optimal PI parameters were obtained for inner-loop recursive PI controller with the method of third-order optimal design. A stable DC-link voltage is the prerequisite for normal operation of RPC, so a sub-PI control strategy was proposed to suppress DC-link voltage fluctuation, which is an accurate feedback control based on energy balance. Finally, the correctness of the analysis has been confirmed by the simulation and experiment results.