CRITICAL ENERGY FOR DIRECT TRANSIENT STABILITY ASSESSMENT OF A MULTIMACHINE POWER SYSTEM.

The authors describe a criterion for determining the critical energy used in direct transient stability assessment of a multimachine power system using the transient energy function method. This criterion provides a method by which the controlling unstable equilibrium point (u. e. p. ), for the disturbance under investigation, is identified. The proposed method is practical and reliable. It is practical in that it offers for a typical multimachine power system a technique for fast determination of the desired controlling u. e. p. , among that several candidate ones. It is reliable in that it has been tested on two medium-size power networks, and in rather complex situations. In all cases the correct u. e. p. was identified and verified using detailed system trajectories.