A network disturbance module for a control device of a wind energy installation having a generator driven by a wind rotor and a converter for producing electrical power fed into a network. The module includes a measurement device configured to measure at least one electrical parameter of the network, a detector configured to identify a network disturbance and output a switching signal, and a reference generator configured to produce a substitute reference vector for the converter based on the at least one electrical parameter. The module also includes a fault management unit comprising a fault classifier, the unit being configured to interact with the measurement device, detector, and reference generator such that, in the event of an undervoltage during island operation, a quick-action frequency regulator is activated. The regulator acts on the converter to vary a real-power feed P in the event of a discrepancy in a network frequency.