With the increasing use of cables in distribution networks, it has become more difficult to extinguish arcs in single line-to-ground (SLG) faults. To address this, a novel and flexible voltage arc suppression technique for SLG faults in distribution networks based on power routers (PR) is proposed. First, a modular multilevel converter (MMC)-based PR topology with a grounded high-voltage DC is introduced. A proportional integral resonance (PIR) controller in the dq0 synchronous rotating frame (SFR) is applied to track the zero-axis vector without steady-state error. This enables real-time regulation of the system zero-sequence voltage so that it matches the magnitude but opposes the phase of the power source electromotive force of the faulty phase. As a result, the fault phase voltage is suppressed below the arc reignition voltage at the fault point, achieving active voltage arc suppression for grounding faults. Then, by precisely controlling the linear reduction of the system zero-sequence voltage and observing whether the zero-sequence current varies linearly with it, the method can determine whether the fault is transient. Considering various fault conditions, MATLAB/Simulink simulations show that the fault phase voltage can be reduced to about 10 V. Further experiments on a physical system platform verify the effectiveness and reliability of the proposed PR-based flexible voltage arc suppression method.