Investigation and optimization of a pre‐stressed tuned mass damper for wind turbine tower

Abstract

Summary With the development of megawatts wind turbines, excessive vibrations of the flexible and slender wind turbine tower under wind excitation have become increasingly prominent. To enhance implement ability of the passive control device for the tower, a new type of passive pre‐stressed tuned mass damper (PS‐TMD) is proposed in this study. A simplified mechanical calculation model of the tower with the PS‐TMD device is established, and the dynamic coefficient and vibration reduction mechanism are deduced through theoretical analysis. And then the design procedure including the optimal pre‐stress and damping coefficient for the proposed device is presented. The numerical simulation example shows that the tuning effect of PS‐TMD is better than the traditional tuned mass damper under the same conditions. The results from a shaking table test demonstrate that acceleration and dynamic displacement response are reduced about 20% and 30%, respectively.

Vibration Control of Steel Wind Turbine Tower Using a Novel Tuned Mass Damper Refitted via Inner Platform

“…A conventional TMD is usually installed at the nacelle of WTT, but an unavoidable issue is that the maximum stroke of this TMD will reach to 0.75 m under the wind or wave loads [24]. Tis means that it has no enough space to deplete the energy in practical application since the engines and gears are located in the nacelle [27]. On the contrary, the internal available space of tower is close to 4 m, so IP-TMD installed inside the tower can play a practical role in dissipating hysteresis energy.…”

“…In addition, because the blades do not provide the lateral stifness of nacelle motion, the tower can be simplifed as a tapered tubular cantilever column, with a concentrated mass M representing the rotor and nacelle at the tower top [26], as shown in Figure 2. According to the principle of generalized displacement, the horizontal displacement x (z, t) of tower section at the height z can be expressed as follows [27]:…”

“…Q denotes the relative displacement between IP-TMD and tower wall. M 1 , c 1 , k 1 , and F ef (t) are the generalized mass, stifness, damping, and equivalent load of steel WTT, respectively, and they can be gained in terms of virtual work principle as follows [27,28]:…”

“…Te structural dynamic responses of steel WTT and IP-TMD are assumed as the harmonic response forms at steady state, and the motion equation of the linear WTT and IP-TMD system is solved by using the harmonic balance method (HBM) [27,29]. Hence, the dynamic responses of WTT and IP-TMD at steady state can be obtained as…”

“…Te symbols (_) and (_ _) are the frst-and second-order derivative with respect to t, respectively. Te generalized equivalent load of steel WTT is assumed as the sinusoidal form [27], and it can be expressed as…”