Hydroelectric power plants need to ensure an uninterrupted energy supply. To achieve this objective, activities of maintenance and inspection are done periodically. The use of divers to do these maintenance in submerged areas, implied high risks for them. In this sense, the automated inspection of such facilities through underwater vehicles can be a satisfactory solution. This article presents a comparison between two control techniques applied to underwater vehicle, Feedback Linearization and Sliding Mode.These strategies are responsible to ensure the following two requirements. First, to make the vehicle overcome the velocity gradient caused by dam's water intakes. Second, to follow the desired trajectory. The control laws were tested by analysing their performance in a helical reference trajectory with the presence of disturbance caused by water intakes.

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Abstract:With the growing energetic need present in the world, it is increasingly necessary for the researches and facilities to seek a better use of renewable natural resources. This paper is applied in the study of the performance of the aeration system of the Francis turbines present in Itaipu Hydroelectric Power Plant. When a Francis turbine operates off its optimal conditions, a vortex is formed inside the draft tube that, besides produces cavitation and pressure fluctuations, can pulse at frequencies with risk of resonance with hydraulic system, producing efforts and vibrations that may cause structural failures in the turbines, generators and civil parts of the power house. These damaging effects can be reduced using atmospheric aeration of the turbines. Because of this, the availability and effectively of the aeration system is fundamental to smooth the behavior of the turbines, helping preserve the health of the power plant. An analysis of the performance of the aeration system will be done using maintenance records and disturbances analysis reports (RAP), allowing verification of the operating conditions of the turbine and fatality of water inlet in air pipes. Through the improvements detected, it is possible to reduce machine stoppages by tripping, thus increasing the availability of the turbines.