A method (36) of short-circuiting a faulty submodule (12, 12', 12") for a voltage-source power converter (8) is disclosed. The submodule (12, 12', 12") is based on a full-bridge, asymmetric full-bridge or half-bridge circuit design having power semiconductor switches(T1-T4) with anti-parallel freewheeling diodes (D1-D4) and optionally non-controllable semiconductor valves (D1'-D4'). The method 36 includes identifying a faulty semiconductor device and determining a failure mode selected from a short-circuit failure mode and an open circuit failure mode. The method further includes selecting a minimum number of power semiconductor switches suitable to provide a bypass path through the submodule depending on the identified faulty semiconductor device and the determined failure mode and driving the selected power semiconductor switches by a modified driving voltage compared to normal operation to cause them to break down in order to provide a durable, stable, low impedance short-circuit path (37a-37d) between the AC voltage terminals (28, 29) of the submodule (12, 12', 12"). A power converter (8) comprising a series connection of such submodules (12, 12', 12") and supporting the method (36) of short-circuiting a faulty submodule (12, 12', 12") is also disclosed.