The invention discloses a dynamic unbalance online testing and fault identification method and
system for wind
turbine generators. The method includes the following steps that within a set
time duration, synchronous sampling on the generator power, the
pitch angle position, the wind wheel rotating speed and the accelerated speed of a cabin in the front and back direction is carried out; according to the generator power and the
pitch angle position collected according to synchronous sampling, whether a draught fan runs under the designed testing work condition or not is judged; if it is judged that the draught fan runs under the designed testing work condition, at least
spectral analysis is carried out on
time series of the collected wind wheel rotating speed; according to results of the
spectral analysis on the
time series of the collected wind wheel rotating speed, whether the draught fan has
impeller unbalance faults or not is judged; if the draught fan has
impeller unbalance faults, either pneumatic imbalance or quality moment imbalance is the reason of unbalancedness is judged according to the results of the
spectral analysis on the
time series of the accelerated speed of the cabin in the front and back direction. The invention further discloses a corresponding
system.