Short-term monitoring of turbine supporting structure in ambient and in-operation conditions

Abstract

Paper presents research of short-term monitoring of vibration response of turbine table top foundation structure in Power Plant Nikola Tesla - A: unit A4 in Obrenovac – Republic of Serbia. Research included short-term monitoring of vibration of the structure in ambient and in-operation condition, numerical modelling of the structure according to available information of masses and stiffness of structural elements, as well as extraction of mode shapes and operational deflection shapes. Measurement of vibrations, during in and out of operating conditions, carried at the same set of points on the upper slab of foundation supporting structure using sensitive accelerometers in frequency range of 0 - 300 Hz, while acquisition carried out using 24-bits acquisition system. Extraction of modes, frequencies and shapes, carried out using state of the art software package ARTeMIS. The same extraction procedure applied for extraction of deflection shapes according to acquired acceleration data during in-operation conditions. Numerical modelling performed using SAP2000 software package for structural static and dynamic analysis, with application of beam elements and additional masses with eccentricity from top level of the foundation structure. Additional masses, according to available data of weights of turbines, turbogenerator and other installed equipment, are taken into account. Finally, during analysis and comparison of experimental and numerical results, find out quite good matches of mode shapes and operational deflection shapes, which clearly have been discussed in conclusion.