Resistance-variable crowbar protection circuit and resistance-variable crowbar resistance setting method thereof

The invention discloses a resistance-variable crowbar protection circuit and a resistance-variable crowbar resistance setting method thereof. According to the resistance-variable crowbar protection circuit, by arranging a resistance-variable crowbar protection unit in a doubly-fed wind power system, the working time of a crowbar during the failure duration can be effectively shortened, the reactive power absorbed by a doubly-fed induction generator operating with the crowbar can be reduced, the stator voltage can be supported, the reactive power oscillation peak of the doubly-fed induction generator during failure clearing can be lowered maximally, power grid voltage recovery can be accelerated, and the power grid voltage stability of areas around a wind power plant can be improved; and inaddition, the resistance-variable crowbar protection unit further can adaptively adjust the dynamic crowbar resistance value to provide effective reactive power support for a failed power grid according to different power gr