WIND ENERGY SYSTEM AND METHOD FOR IDENTIFYING LOW-FREQUENCY OSCILLATIONS IN AN ELECTRICAL SUPPLY NETWORK

Provided is a method for identifying low-frequency oscillations, in particular subsynchronous resonances, in an electrical supply network, wherein the electrical supply network has a line voltage with a nominal line frequency, comprising the steps: detecting at least one electrical signal of the electrical supply network as at least one test signal and filtering and/or transforming the at least one detected test signal into at least one check signal, temporal derivation of the at least one check signal or difference formation of temporally separated values of the check signal, in order to obtain a gradient signal in each case, identifying the presence of a low-frequency oscillation if the gradient signal or at least one of the gradient signals meets a predetermined check criterion, in particular at least one predetermined check limit is exceeded.