Aiming at the deficiency of the voltage support from static var. generator (SVG) in the fault control of adaptive STATCOM and line converter (SLCC) systems, a voltage proportional feed-forward control strategy is proposed. By analyzing the operation mechanism of SLCC, this paper holds that accelerating the Commutation Recovery Stage is the key to suppressing commutation faults. On this basis, a proportional feed-forward controller was designed to rapidly enhance the equivalent voltage of SVG, thereby accelerating the recovery of commutation capability. A proportional gain optimization criterion was established to balance fault mitigation and device safety. PLECS simulation shows that this method significantly improves the commutation safety under fault conditions and achieves zero commutation faults in the most common single-phase grounding faults.