A new design solution for photovoltaic (PV) power plants is the use of
Floating PV systems (FPVS), which are generally installed on bodies
of water such as natural lakes, dams, reservoirs, or the ocean. This
market is expected to expand because floating PV systems cause
less environmental pollution problems than the traditional
approach to the development of solar power. This paper
introduces a method to conduct the hydrodynamic analysis
of floating PV structures using ANSYS AQWA as well as a
structural analysis of floating PV structures that considers the
response characteristics over time.
The analysis process
The installed floating photovoltaic module structure is
exposed to severe environmental loads such as winds and waves.
Therefore, the FPVS engineers needed to establish an analytical
process for conducting a structural evaluation of the robustness of the
solar structure and the solar modules. To this end, our team proposes
a four-step process of numerical analysis of the FPVS to understand
the hydrodynamics and structural characteristics of floating solar
structures, consisting of:
- CAD modeling using ANSYS SpaceClaim
- Computational fluid dynamics (CFD) analysis of wind load
using ANSYS AIM or ANSYS Fluent
- Hydrodynamic analysis of wave and wind speed using ANSYS
AQWA
- Time response analysis of the overall structures using ANSYS
Mechanical
To summarize, firstly we used ANSYS CFD AIM for fluid dynamics
analysis on the extraction of load data. Then, we used ANSYS AQWA
for hydrodynamic analysis of the aquatic conditions and environmental
loads. Lastly, we used ANSYS Mechanical for the structural analysis
of the Floating PV structure, including the frames and solar panels.
Model description (TSNE’s Arbitrary Model)
We used three types of models for the different analyses (Fig.1)
Hydrodynamic analysis using ANSYS AQWA
Since the use of AQWA in this analysis process is different from
the general analysis method, we have explained it in more detail.
The fluid dynamic analysis to derive the loads on the panels of the
floating solar structure was conducted with ANSYS CFD AIM, and the
hydrodynamic analysis of the water conditions and the environmental
loads was conducted with ANSYS AQWA. It is important to emphasize
the use of ANSYS AQWA in our analysis process. Firstly, we ran a
Hydrodynamic Diffraction analysis of the floating body to check
its stability. Secondly, we obtained the specific behaviors of the
floating body itself using hydrodynamic response analysis. Then,
we conducted a simulation that considered the environmental loads
created by the wind and waves to obtain the data of the structural
position of the floating body. (Please see the red-dotted box in Fig. 2)
Results
Fig. 3 shows the results of the CFD analysis in terms of the total
speed and pressure of wind from the direction of 90 degrees and
from 180 degrees.
We extracted each X, Y, Z Force component according to the wind
direction from -180 degrees to 180 degrees of total wind force with CFD analysis using
parametric variables, as
shown in Fig. 4.
We transferred these wind
force data to wind load
coefficients by dividing by
the square of the velocity.
This wind load coefficient
condition applies to the
hydrodynamic analysis of
floating structures.
Fig. 5 shows the wave surface elevation over time using the
hydrodynamic diffraction with the above-mentioned wind coefficient
results. This result shows the wave properties such as diffraction
and radiation around the floating structure according to the wave
conditions such as wave direction and wave height. The highest wave
height was found to be 0.26m at the 0.2sec period.
Finally, Fig. 6 shows the results of the transient structural analysis.
These represent the maximum stress on the structure over time with
the solar sample model installed in the water-based environment.
The analysis revealed that the sample model
experienced its most unstable structural
state at 0.4 sec and a maximum stress of
184 MPa.
Conclusions
Since no analysis process exists for the
structural evaluation of a Floating PV
installation, it was necessary to establish an analysis process to
accurately examine the environmental loads and structural stability
of a Floating PV. With this purpose in mind, this paper presents a
method of conducting a hydrodynamic analysis of a Floating PV in
its water-based environment and a structural analysis for examining
its structural stability according to the characteristics of motion it
undergoes. ANSYS AQWA enables various problems to be included
in the analysis such as multiple environmental conditions including
the fender, the joint, the cable winch, irregular waves, birds, etc.
Furthermore, a fatigue analysis can be conducted to evaluate the
fatigue life of the Floating PV.
Newsletter EnginSoft Year 16 n°4
By Jeongpil Hwang and Eunsil Han | Taesung S&E
References
[1] “ANSYS AQWA Reference Manual Release 2019 R2”, 2019
[2] “ANSYS AIM Manual Documentation 2019 R2”, 2019
[3] Yeom Duckjun, Dynamics of Marine Structure, UUP, 2010
