During power reduction transitions of a fuel cell power plant, the excess electric energy generated by consumption of reactants is extracted, during one or more periods of time, by a voltage limiting device control (200) in response to a controller (185) as i) energy dissipated in a resistive auxiliary load or ii) as energy applied to an energy storage system (201) (a battery), in boost and buck embodiments. The controller operates the voltage limiting device control in response to the positive time derivative of the voltage of one or more of the fuel cells exceeding a predetermined limiting value.