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| Author(s): |
Ivo Sechi Nazareno
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) |
| Defense date: | 2003-08-11 |
| Examining board members: |
Newton Geraldo Bretas;
Luís Fernando Costa Alberto;
Laurence Duarte Colvara
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| Advisor: | Newton Geraldo Bretas |
| Abstract | |
In transient stability assessment, the nonlinearities of the systems and the dimension of the problem contribute to the complexity of the analysis in power systems. The classical numerical solution to obtain the critical clearing time (cct) has been used, but it is time-consuming and not adequate for real-time applications. The direct methods have the adequacy for real-time analysis because they get the necessary information for stability without the explicit solution of the set of differential equations associated to the system dynamics. Among the existing methods of power system transient stability analysis, Lyapunov ideas associated to LaSalle´s invariance principle are very important. Inspired by these ideas, methods to estimate the stability region have been obtained. One of them is the BCU, that has been accepted as the most efficient method in the determination of the critical cct. Despite BCU´s efficiency, it fails in many cases. The main objective of this research is to solve two problems associated to the BCU: the first problem is the fact that not always the maximum of potential energy occurs in the neighborhood of PEBS. The second problem is the fact that in many cases the trajectory of the reduced gradient system does not pass in the neighborhood of the controlling unstable equilibrium point. For the solution of these problems it will be used a dynamic method for the exit point detection and the Shadowing Method to calculate the controlling unstable equilibrium point. Tests have shown that the aforementioned robust algorithms find the solutions for many cases for which BCU and PEBS method fails, but many cases of fail persist. Some alternative methods, based in the mentioned algorithms are proposed, and so, aspects to improve its convergency. (AU) | |