Hydrostatic transmission in wind turbines : Development of test platform

University essay from Linköpings universitet/Fluida och mekatroniska system; Linköpings universitet/Fluida och mekatroniska system


This master thesis project is a part of a larger project with the goal of develop-ing a drivetrain, utilizing a hydrostatic transmission, for horizontal axis mid-sizewind turbines. Some of the benefits from using a hydrostatic transmission are thata variable speed operation is possible without the use of a frequency converter,the generator may be placed on the ground and thus reduce weight in the nacelleand also using hydraulic components can increase lifetime and robustness of thesystem. The thesis work is a part of the second step towards this goal, whichcontains constructing a test platform of the concept.

The test platform is being built at the Laboratory of Hydraulic and PneumaticSystems (LASHIP) in Florianópolis, Brazil, where also the master thesis projecthas been conducted. Two companies are involved in the construction of the plat-form, Parker Hannifin and Reivax. Parker Hannifin is a multinational diversifiedmanufacturer of motion and control technologies and systems. Reivax developtechnologies for control systems and automation applied in Hydroelectric, Ther-moelectric and Nuclear power plants.

The project was performed during the period of February to August 2015 andgoverns dimensioning and selection of hydraulic components for the test platform,development of simulation model in AMESim, evaluation of control strategies andalso a dynamic analysis of the system.

Dimensioning the platform resulted in a drivetrain with an output power of28 kW. Standard hydraulic components with high efficiencies where selected fromParker’s product portfolio. These components were then modeled in AMESimwhere simulations of the whole system could be performed. Control strategieswere tested and results showed that the best performance is reached when usinga regulator that is able to compensate for pressure changes in the system. Re-sults also indicated that the hydrostatic transmission can perform very well as areplacement of frequency converters, in terms of stable frequency output of a vari-able wind turbine. The dynamic analysis showed that the parameter that sets themain characteristics of the system is the aerodynamic rotor with its large inertia.

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