Stability assessment of highly stressed power systems using the sparse formulation of the direct method

In the stability assessment of large-scale power systems using the direct method, slow convergence and ill conditioning of computation often occur when highly stressed systems are analyzed. The authors describe a robust computerized technique to assess the transient stability of such systems using the sparse formulation of the transient energy function method. This technique combines a direct method of Gaussian elimination and a least-squares iterative method to calculate the Newton step needed in the calculation process of the unstable equilibrium point. The technique is applied to a 108 generator, 252 bus highly stressed utility system, characterized by large power flows over weak transmission links. The superiority of the sparse formulation to handle large-scale ill-conditioned systems is demonstrated