An Approach to Suppress Low-Frequency Oscillation with CHB-STATCOM based on improved sliding mode control in Vehicle-Grid System

To suppress the low-frequency oscillation (LFO) phenomenon in vehicle-grid coupling system, the single-phase cascaded H-bridge static synchronous compensator (CHB-STATCOM) is applied to traction network to compensate reactive power. To improve dynamic performance and robustness of the system, this paper proposes an improved sliding mode control (SMC) strategy for CHB-STATCOM. First, to completely decouple active and reactive power, the exact linearized model of CHB-STATCOM in dq frame is deduced by coordinate transformation and state feedback. Then, the voltage outer loop and the current inner loop are both designed as sliding mode control. Finally, the simulation results show that the proposed method has good control performance and LFO suppression effect.