Transient stability assessment for network topology changes: application of energy margin analytical sensitivity

Developments in direct transient stability assessment using the Transient Energy function (TEF) method have included the exit point technique to determine the controlling unstable equilibrium point (u.e.p.). In this paper, analytical sensitivity of the energy margin is coupled with the exit point based TEF method to assess system stability when there is a change in system parameters: plant generation or network configuration. The principal features of this paper include: introduction of a very fast sensitivity technique to account for network configuration changes; elimination of the assumption that the mode of disturbance of the controlling u.e.p. does not change; and correlation of the sensitivity results with time simulation through swing curves. The technique is tested on the 50-generator IEEE test system and the 161-generator Northern States Power (NSP) system