Fuzzy assessment of power system transient stability level based on steady-state data

Following extensive analysis of the relationships between the transient instability behaviour of large-scale power systems and the corresponding prefault operating states, a novel heuristic method based on fuzzy reasoning is proposed in the paper for the fast evaluation of the power system transient stability level (TSL). A notable feature of this method is that it does not rely on the step-by-step simulation process and only system load-flow data under normal operating conditions are used for the assessment. A generalised critical clearing time (GCCT) is defined that can be predicted by the proposed method to describe the TSL. Digital simulations based on two power systems show that the proposed method provides broadly conclusive and decisive real-time information about the stability states of the studied power systems.