A number of standard power system models implement non-windup limits on control blocks in ways that can lead to trajectory deadlock. This deadlock behaviour takes the form of infinitely fast switching, due to incompatibility between the conditions that govern switching on either side of the switching surface. Solutions can only be continued in a Filippov sense. The paper explores this phenomenon in the context of a standard voltage regulator model, and an industry-standard model of a doubly-fed induction generator that is widely used to represent wind turbine generators. Two approaches to preventing deadlock are considered: the first employs a deadband, while the second uses feedback.