Using Critical Machine Couple Equal Area Criterion to Assess Multi-Machine System Stability

This paper extends consistency of single machine equal area criteria and transient energy function based direct method to multi-machine system. Based on these characteristics, an approach to transient stability assessment is proposed. In multi- machine system, two generators of best forward angle and best lag angle named critical generator couple is selected, equal area criterion (EAC) is applied to them, and incorporating time domain simulation (TDS), transient stability assessment is obtained. The advantage of this approach is that it avoids generators equivalence and network reduction and needs less computation time, less information, it has the same accuracy as time domain simulation in assessing stability and system model is applicable widely. Validity carried out on a New England test system of 10 generators is reported.