The power electronics based equipments are always installed in traction substations, for the purpose of negative sequence and reactive power compensation. The negative sequence current injected into and the reactive power absorbed from power grid will be none, if the RPC is used in a traction substation with Scott transformer. For the controller is usually adopted as an indirect method, the compensation effect is not very well because of the uncertainty and deviation of parameters and disturbances. Therefore, a direct-control method is proposed, which sample the signals from and follow-up the presetting of the high-voltage coil terminal. For the direct-control method has a closed-loop structure, it will achieve a better control effect. The validity and effectiveness are verified by the simulations.