ES220411 test WHG

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Wind, Hydro and Geothermal Power Generation AY 2021-22 11th April 2022 Prof. Paolo Silva Time: 90 minutes Instructions for the examination: 1) Clearly indicate your name on all the sheets you will deliver. 2) Give a synthetic and clear answer to as many questions as possible. The final score will be normalized according to the average results. 3) Talk with colleagues and / or cheating will cause the cancellation of the exam. 1. Considering a large scale three-bladed horizontal axis wind turbine, discuss the regulation strat- egies adopted by the control system in the range between the nominal and cut-off wind speed, explaining the main pros and cons of each of them. In particular highlight the velocity triangle modification introduced by a gust. (5 points) 2. Considering a geothermal power plant, highlight pros and cons of a binary cycle configuration versus a direct-steam cycle one. Which kind of geothermal source has the greatest advantages in adopting a binary cycle? (5 points) 3. Consider a pumped-storage hydro power plant operating with a nominal head of 250 m and a given average head loss within the penstock of 15 m. Explain how to compute the minimum energy price differential required to make the operati on of the plant cost-effective. Illustrate the assumptions made for the unknown parameters. (5 points) 4. Discuss the characteristics of floating technology with respect to offshore wind installations based on foundations. What are the main advantages and disadvantages? (5 points) Exercise (10 points) A geothermal source has the following characteristics at the outlet of the well: temperature 180 °C, enthalpy 1800 kJ/kg. Consider a single flash direct steam cycle plant, based on a cooling tower condenser with a condensation pressure of 0.07 bar. The flash…