Online identification of coherence based on nongenerator bus voltage angles correlation coefficients

In this paper, a new approach for identifying coherent groups of generators in power systems based on the correlation coefficients between bus phase angles is presented. The method uses a new clustering index based on the correlation coefficients of bus phase angles. The proposed approach uses real time data of bus phase angles via PMUs, so it is able to easily take into account the effect of system detailed modeling, generators and system controllers and type of events. The proposed correlation index evaluated from the real time behavior of power system in time-domain following disturbances are used to evaluate the degree of coherency between any pair of buses. The bus phase angle can be obtained from synchronized measurements of system quantities using PMUs. Hence, the proposed method could be integrated into a wide-area measurement system enabling fast identification of coherent groups of generators. The proposed method is tested on the IEEE 39-bus with 10 generators.