Synthesis and Robustness Analysis of a Damping Control Systems subject to Parametric Uncertainties
Leiliane Borges Cunha1; Erick Melo Rocha1; Anderson de França Silva1; Walter Barra Junior1; José Augusto Lima Barreiros1
1 Federal University of Pará
doi:10.20906/CPS/USM-2016-0041
Resumo
Different control techniques for electrical power systems have been developed in the last years, mainly to damp low frequency oscillations, which are harmful for system operation and impose limitations on the power transfer, lowering the total transmission capacity of the system, which can lead it the instability. With this purpose, damping controllers were designed following certain control specifications, such as minimal damping desired for the dominant electromechanical modes, and robustness for parametric uncertainties of system operating parameters. Conventional techniques for Power Systems Stabilizers (PSS) design consider only a specific point of operation and, therefore, disregard parametric uncertainties common to the real systems, jeopardizing the dynamic performance of the system. For this reason, this paper presents the design of a damping controller for an infinite bus machine system using techniques of robust control as Convex linear programming and the Chebyshev theorem. The goal is to determine the controller parameters, and to compare the results with the performance obtained by using a conventional method for different system operating conditions. The Convex linear programming is used in order to perform convex optimization of an objective function based in a linear inequations set, which covers polytopic uncertainties of the plant, and estimates the optimal values of the controller parameters, satisfying system performance. Traditional techniques such as Pole-placement are also shown for comparison purposes. The two controllers have been tested and it was verified that both were successful on damping the system oscillations, but the robust controller presented a more smooth and robust response when both were subjected to parametric variations in the mechanical power of the machine, providing a controller with smaller effort during the transient, principally when shifted the operating point.
Palavras-chave: Robustness; Power Systems Stabilizers ; electromechanical modes; parametric uncertainties