Transient Stability Program Output Analysis

The output of a conventional transient stability program is analyzed using transient energy functions for individual machines. The analyst is provided with a quantitative index of the degree of stability or instability for each generator. This index is useful for guiding the selection of subsequent case studies. The transient energy consists of two components: kinetic and potential energy. In the post-disturbance period, profiles of the kinetic energy (VKE), the potential energy (VPE), and the time derivative of the potential energy (VPE) are obtained. These are used to develop a criterion for the degree of stress on a disturbed but stable machine, and to assess the extent of instability for an unstable machine. The method of analysis has been tested on two power networks representing the system of the state of Iowa, and validated by studies on a Philadelphia Electric Co. network.