A device for cancellation of parasitic voltage on the neutral line and for adjusting phase-to-neutral voltage at the remote end of a long power line comprises an autotransformer and at least two single-port-to-multi-port controllable selectors and a controller. The controller is adapted to enable educated selection of taps of the autotransformer by the controllable single-port-to-multi-port controllable selectors, for setting the phase-to-neutral output voltage to nominal voltage and for canceling the parasitic neutral-to-ground voltage.