On-load tap changer control method for a power excitation chain, related unit and power excitation chain comprising such unit

The present invention relates to an on-load tap changer control method for a power excitation chain (1), said chain (1) comprising - a generator (3), - a step-up transformer (5) equipped with an on-load tap changer (7) and connected on the one hand to the output of said generator (3) and on the other hand to a transmission bus (9), and - an excitation control system (11) comprising a generator automatic voltage regulator (AVR G ) and at least one excitation limiter (OEL G , UEL G ), comprising the following steps : - monitoring the excitation conditions of the generator, - activating said at least one excitation limiter (OEL G , UEL G ) when the monitored excitation conditions are outside a predefined range, inhibiting temporarily the change of step of said on-load tape changer (7), when said excitation limiter (OEL G , UEL G ) is active.