Environmental Engineering Reference
In-Depth Information
Fig. 12.9
Semiactive tuned liquid column damper [
2
,
3
]
The semiactive Tuned Liquid Column Damper (S-TLCD) [
2
-
4
] uses the effects
of the tank geometry to change both its natural frequency and damping ratio.
Hereby, a control system identifies the dynamic properties of the turbine tower by
sensors and calculates the optimum parameter of the damper. The semiactive
damping system can tune itself to the changing tower dynamics, which are pri-
marily caused by degradation effects, temperature, and soil conditions. To modify
the frequency, S-TLCD uses movable panels, which change the flow area of the
vertical sections of the damper tank. The damping ratio is adapted by using an
orifice as patented by Sakai [
29
]. As a result, compared to a passive strategy,
thanks of the permanent optimum tuning of the damper parameters, S-TLCD
works more efficiently. Figure
12.9
shows the S-TLCD with a horizontally excited
structure. In the side view of the damper the movable plates are illustrated.
The dynamic properties of S-TLCD can be determined using the Bernoulli
equations as described in the last section for TLCD. Hereby, the effective lengths
L
1
and L
2
are calculated by Eq.
12.16
and
12.17
. The equation of motion and the
frequency equation of TLCD (Eq.
12.8
-
12.9
) can be used furthermore.
L
1
¼
2V
3
þ
V
2
þ
A
V 2
A
V 1
ð
2V
1
þ
V
2
Þþ
A
V 2
A
H
H
ð
12
:
16
Þ
L
2
¼
2V
3
þ
V
2
þ
A
V 1
A
V 2
ð
2V
1
þ
V
2
Þþ
A
H
A
V 2
H
ð
12
:
17
Þ
12.4 Reference Wind Turbine with Tuned Mass Damper
The effectiveness of TMD and TLCD is numerically verified by means of a 5 MW
reference onshore wind turbine. In this chapter, the following calculations are
presented:
• Onshore wind turbine with TMD
• Onshore wind turbine with TLCD
• Seismically excited onshore wind turbine with TMD
• Onshore wind turbine with TMD considering SSI
