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DEVELOPING MAINTENANCE PROGRAM FOR SMALL HYDROELECTRIC POWER PLANT USING VIBRATION MEASUREMENTS AND SIMULATION

Assoc. Prof. Cornel Dumitru Ilinca, Assoc. Prof. Vlad Florin PIRAIANU

Abstract

Small hydroelectric power plants (SHPP) are accepted by the legislation of EU Member States to benefit from renewable energy promotion scheme through various market mechanism. The SHPPs are a particular form and case of hydroelectric power plants (HPP) and are having a maximum capacity of 10 MW. Since the green certificate (GC) promotion scheme was awarded in Romania (2008), a considerable number of SHPP were constructed and commissioned in the last years. These projects have the same philosophy as a large hydro, but their impact on the environment is considered to be less due to the dimensions of their structures. Also the dimensions of units below 10 MW are much reduced than bigger units. The entire technical parameters are different in SHPP than regular HPP therefore we find higher speeds of the machines, simple construction of hydraulic structures, less equipment and auxiliary systems, reduced dimensions of turbines, generators or inlet valves that are having an important influence in their complexity. Comparing to a 55 MW Francis unit that has a nominal speed of 375 rpm, a 400 kW Francis unit could reach easily 1000 or 1500 rpm. This will reduce the number of electromagnetic pols of generator and therefore its dimensions and more important the manufacturing cost. However, the maintenance requirements of the other components remain the same as in large project or even higher. As an example, the bearings of the turbine are subject to a higher speed and wear, the water has a higher speed through turbine and guided vanes. Also a SHPP that is built on a derivation layout, does not have a large reservoir that allows the regulation of discharge in order to limit the number of start-ups per day. The SHPP will start depending on the water availability in the forebay tank and will shut down when the minimum level its achieved. This is causing higher stress of material, fatigue and additional wear of mechanical equipment. Most of the SHPP that were built are subject to maintenance works as they exceeded warranty period. It is very important to plan the maintenance during periods with low hydrology, especially in summer. The limitation in water storage capability of any SHPP generates significant energy losses when maintenance is required. It is very important to know and understand the actual state of the machines in order to optimize maintenance in order to maximize energy generation and minimize any losses. Therefore, it might be the case of establishing a limitation in operation until maintenance conditions are met. This article aims to presents the results in the field of SHPP maintenance by using vibrations measurements and numerical simulation in order to determine the actual state of the units and for their components, and to obtain enough knowledge to properly organize the entire maintenance program.

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DOI resolver: doi.org/10.5593/sgem2017/42/s17.024

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