Coherency Analysis of Disturbed Generator Groups Based on TwoStep Cluster

Based on TwoStep Cluster, a new method to analyze the coherency of disturbed generator groups is proposed. Firstly, the generator rotor speed gathered from the Wide Area Measurement System (WAMS) is disposed to build CF tree and produce sub-clusters by dint of BIRCH algorithm method; then through hierarchical clustering, the sub-clusters are clustered into the specified number of clusters that is automatically determined; finally the clustering result is used to analyze the coherency of the disturbed generator groups. The effectiveness of applying the proposed method to identify the coherent generators, as well as the feature to determine the clustering numbers automatically, is verified by simulation of New England 10-machine 39-bus system and by comparing the results of different methods of identification of coherent generators.