When a power system is at the status of heavy load with line break causing the change of network structure

its power flow calculation is usually difficult to converge and it is hard to carry out the coherent generator identification based on slow coherency method due to the large condition number of Jacobian matrix. In order to improve this

a novel approach of generator coherency identification is proposed considering the line break. The basic processes of the method are as follows. Firstly

by describing the π-equivalent line model as a model with parameters

the event of branch line break is therefore expressed as the process of parameter variation. Then the novel method based on predictor-corrector continuation algorithm is further designed to compute the state matrix's eigenvalues and their corresponding eigenvectors of the new network after the line break. Finally

the coherency indices between each pair generators and the coherent generator groups under the new network structure are acquired. The novel method proposed has good convergence property when the system is verified in the condition of heavy load and line break through the New England 10-unit 39-bus power system.