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Incorporation of nonlinear load models and identification of the inter-area mode phenomenon in the transient energy function method

Thesis/Dissertation ·
OSTI ID:6156739

Considerable progress has been made in first swing power system transient stability assessment using the transient energy function (TEF) method. The basic approach consists of representing the effect of nonlinear load models on the stable equilibrium point (SEP) and the controlling unstable equilibrium point (UEP) solution. An alternate network solution procedure is used to reflect the effect of the nonlinear load models, via current injections at the internal generator nodes. The power corresponding to these injections is then included in the mismatch equation for the SEP and UEP solution. A new expression for the TEF is developed to include the term corresponding to the nonlinear load components. The proposed technique has been tested on a 4-generator system and a 17-generator system. The other aspect of this research work deals with the application of the TEF method to stressed large-scale power systems. The theory of modal analysis has been used to identify the inter-area mode phenomenon of stressed systems. The inter-area mode phenomenon can be described as the tendency of a large group of generators (including the small group severely disturbed by the fault initially) to separate from the rest of the system as a result of instability. The post disturbance network of stressed systems are characterized by weak synchronizing forces caused by large transmission impedances, and thus generators away from the fault location may also separate from the system. The proposed techniques has been tested on three test systems, the 17-generator Iowa system, the 50-generator Ontario-Hydro system and the 126-generator western USA system. Both stressed and unstressed systems have been considered in testing this technique.

Research Organization:
Iowa State Univ. of Science and Technology, Ames, IA (USA)
OSTI ID:
6156739
Country of Publication:
United States
Language:
English