Eddy-Current Tuned Mass Dampers for Mitigation of Wind-Induced Response of the Noor III Solar Tower: Design, Installation, and Validation

The Noor III solar tower of the Ouarzazate Solar Power Station in Morocco is a very slender structure sensitive to wind excitations. Hence, tuned mass dampers (TMDs) were employed to reduce its wind-induced response. Finite-element modeling and wind-tunnel test results were employed to design the parameters of the TMD system. Four 10-t TMDs with eddy-current damping (EC-TMD) were selected for implementation (via a customized steel frame) at the top of the solar tower (i.e., inside the receiver). The effectiveness of the designed TMDs in controlling the tower was numerically studied under free vibration and forced vibration. Then, considering design and modeling errors and the possible need for on-site adjustments of EC-TMD parameters, pendulum-type EC-TMDs were fabricated. Dynamic properties of the tower were identified based on field measurements. With the installation and adjustment of the four designed EC-TMDs, the damping ratio of the Noor III solar tower was enhanced from 0.72% to 3.78%. Field measurements of tower vibrations under strong winds with/without participation of the EC-TMDs showed that significant mitigation of wind-induced response was effectively achieved by the TMDs with eddy-current damping. In addition, the on-site acceleration measured on the prototype tower was compared with the acceleration obtained for the scale model in a wind tunnel to highlight the significant Reynolds number effects on the prediction of the wind-induced response of the solar tower structure.