2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 311 -
Abstract--
Wind Resource assessment in complex site is a
challenging task . A study with a Computational Fluid
Dynamics(CFD) model is explained in this paper.
Sakkulathumedu falls in the high ranges of Western Ghats
in Kerala, India. Western Ghats in general, presents a
succession of cliffs, ridges and conical peaks and is of highly
irregular and rugged in topography i.e. highly complex in
nature. The elevation of the hills gradually decreases
towards west. The complexity of the terrain makes the use
of a linear model impossible. CWET (Centre for Wind
Energy Technology in India) has performed wind flow
computations analysis with the CFD software Meteodyn WT
recently. A fine resolution grid was used, allowing
recirculation zones and flow detachments to be taken into
consideration. The forest areas were modeled by a drag
term approach. Data from four meteorological masts have
been used for the validation of results.
Index Terms
- CFD, complex terrains, forest modeling,
uncertainties
I. I
NTRODUCTION
The wind resource assessment in India estimates the
total wind power potential about 48 000 MW. This
potential is distributed mainly in the states of Tamil
Nadu, Andhra Pradesh, Karnataka, Gujarat, Maharashtra,
and Rajasthan. In India, the wind resources fall in the low
wind regime, the wind power density being in the range
of 200 - 450 W/m
2
and most of the windy areas are in
mountainous complex terrains.
The precise assessment of the wind power potential is
more important as the economics of a project are
crucially dependent on the site wind resource. A change
of wind speed a fewer precent thus makes an enormous
difference in financial terms of both debt and equity.
Generation
of electrical energy from wind can be
economically achieved only
where a significant wind
resource exists. The accurate and thorough monitoring of
wind
resource at potential sites is a critical factor in the
siting of wind turbines. The existing wind data available
at
most of the meteorological stations worldwide is
measured at lower
heights. Therefore,
wind speeds
measured at anemometer heights are extrapolated to the
hub height of the wind turbine. Wind speeds can vary
spatially also. However the extrapolated value may not
give an accurate wind speed values in any of the sites.
The extrapolation in complex site is highly challenging
task.
Computational Fluid Dynamics (CFD) based tools
provide good wind speed prediction for the flows over
complex terrain in micro scale level. The complete set of
the non-linear Navier-Stokes equations, including a
transport equation for the turbulence intensity is solved.
To calibrate the CFD simulations, on-site measurements
from one or more met towers are required. Wind flow
computations have been done over
Western Ghats’s
complex terrain using the CFD software METEODYN
WT and compared the results to onsite measurements.
The error calculated is found to be small so we may use
the CFD solutions as reference to evaluate the accuracy
of two different prediction strategies.
Being the official Wind Energy Certification Centre in
India, C-WET is working on the projects in highly
complex terrain. The past few year results show the
necessity of non-linear applications in order to reduce
uncertainties. Wind flow computations have been
performed in the high ranges of Western Ghats
(Sakkulathumedulathumedu) site in Kerala. The
Sakkulathumedu laid on the Western Ghats 680 km²
mountainous and forested areas with complex
climatological characteristics. The altitude variation in
this area is greater than 1200m.The uncertainties in the
extrapolation are evaluated by the four meteorological
masts: Sakkulathumedu (altitude: 1151 m), Kailasamedu
(altitude: 1120m), Perampukettimedu (altitude :1135m)
and Meenakshipuram (altitude: 440m).
Fig. 1. Topography, mapping area, and met mast locations
(Sakkulathumedu, Meenakshipuram, Perampukettimedu and
Kailasamedu).
Assessment and Analysis of Wind Resource in
Indian Complex Terrain with CFD Model and
Validation
Sreevalsan.E*, Boopathi.K**, and Karim. Fahssis**
*Centre for Wind Energy technology, Pallikaranai, Velachery,
(India)
**Meteodyn (Beijing), RM D 28E, Oriental Kenzo Building,
(China)
