Turn-to-turn protection method and device for converter transformer

The invention relates to the field of direct current transmission converter transformer protection, in particular to a turn-to-turn protection method and device for a converter transformer. The method comprises the following steps: acquiring a grid-side three-phase current value and a valve-side three-phase current value of a converter transformer, calculating a differential current effective value and a differential current instantaneous value, carrying out differential protection judgment according to a brake current effective value and the current differential current effective value, carrying out periodic sudden change judgment according to a memory differential current effective value and the current differential current effective value, and carrying out cyclic sudden change judgment according to the memory differential current effective value and the current differential current effective value. If yes, intermittent locking judgment is carried out according to the memory differential current instantaneo