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Comparative study of PID controller designs for AVR using different optimization techniques

Hesham Haya, Ezzat M., Swief Rania A.

Archives of Electrical Engineering

2021

Vol. 70, nr 3

567--583

This paper presents the optimal PID tuning study to improve the dynamic performance of an automatic voltage regulation (AVR) system. The system under study consists of a synchronous generator whose reference voltage changes in a step function and tries to overcome the transient behavior of its terminal voltage smoothly. To optimally control the performance, different optimization techniques are applied to tune the controller gains to obtain the minimum steady state error (main objective) and better dynamic characteristics (rise time, settling time, max overshoot, etc.). Then the AVR system responses with a PID controller based on different optimization techniques are compared to find out which is the best technique.

Free convection effects on a perfectly conducting couple stress fluid

Ezzat M., Zakaria M., Samaan A., Abd-el Bary A.

Journal of Technical Physics

2006

Vol. 47, no 1

5-30

We have introduced a magnetohydrodynamic model of boundary-layer equations for a perfectly conducting couple-stress fluid. This model is applied to study the effects of free convection currents with thermal relaxation on the flow of a polar fluid through a porous medium, which is bounded by a vertical plane surface. The state space formulation developed in EZZAT [1] and [2j is introduced. The formulation is valid for problems with or without heat sources. The resulting formulation, together with the Laplace transform technique, are applied to a variety of problems. The solution to a thermal shock problem and to the problem of the flow in the whole space with a plane distribution of heat sources are obtained. It is also applied to a semispace problem with a plane distribution of heat sources located inside the fluid. A numerical method is employed for the inversion of the Laplace transforms. The effects of Grashof number, material parameters, Alfven velocity, relaxation time, Prandtl number and the permeability parameter on the velocity, the temperature and the angular velocity distributions are discussed. The effects of cooling and heating of a couple-stress fluid have also been discussed. Numerical results are given and illustrated graphically for the problems considered.