Fast transient stability assessment using large step-size numerical integration

The paper is concerned with fast transient stability assessment for online applications. Normally, direct methods are thought of as the only possible candidates for this purpose but the paper shows that the standard step-by-step method can also be slightly modified to make it suitable for online applications. The dynamics of the interconnected power system with numerous generators are complicated indeed but if the intention is to use the dynamic analysis only to ascertain the first swing transient stability then performing the numerical integration with a large step-size is sufficient. The large step-size integration is fast and accurate enough for online applications. This is demonstrated by simulating three test systems, of sufficient complexity, using the large step-size method and comparing the results with the detailed simulation. The paper discusses why this observation is not very surprising. An algorithm is presented for computing the reduced nodal admittance matrix, an essential part of the analysis. Considerable reduction in computation time and memory requirement is achieved.