LAUSR

Direct methods have been a promising development for decades, receiving, however, less attention recently. One of the reasons is the limited capacity to include more realistic models of the power systems equipment. This paper derives a structure-preserving analytical energy function for a sixth-order synchronous generator model with subtransient dynamics included. The procedure used to construct the energy function is demonstrated to be applicable to simple governor models as well. The energy function is used to assess critical clearing times for multiple contingencies via a potential energy boundary surface method in the IEEE 10-generator 39-bus benchmark system. Some comparative analysis with transient fourth-order models is performed. The results are validated against simulations using a commercial transient stability package.