Study and evaluation of operating parameters of project wind Villonaco of

province Loja-Ecuador

Hans G. Ollague Armijos, Eng – U.P.S. Hugo E. Crespo Azanza, Eng – U.P.S.

Universidad Politécnica Salesiana

The Universidad Politécnica Salesiana is an Ecuadorian university belonging to the Salesian Congregation. The U.P.S. was founded in 1994 in the city of Cuenca and has headquarters in Quito and Guayaquil. It is characterized by technical and Christian education provided to its students.

Insitutional Image. Universidad Politecnica Salesiana sede Cuenca-Ecuador.

Universidad Politécnica Salesiana

MISION:The Universidad Politécnica Salesiana is an institution of higher humanistic education and polytechnic, of Christian inspiration with Catholic character, e Salesian nature; directed preferential manner to youth of popular sectors; seeks to form "honest citizens and good Christians" with academic ability and investigative that contribute to local and national development.

VISION:Being an institution of higher education of reference in the search for truth and the development of the cultural, of investigation scientific and technological; recognized socially for its academic quality, university social responsibility, and for their capacity to incidence in the intercultural.

Universidad Politécnica Salesiana

The UPS has acquired the ANSYS software does aproximately 1 year. This major software has enabled teachers and students to develop and solve problems in fluid dynamics, heat transfer, inter alia.

Goals:

General:

• Characterize, simulate and analyze wind flow in the wind farm Villonaco to determine operating conditions.

Specifics:

• Analyze the wind potential of the wind and the orography of the area of emplacement of the wind farm Villonaco.

• Characterize and simulate the wind flow in the Wind Farm Villonaco, through specialized software in fluid dynamics.

• Perform validation and the analysis of the results obtained of the simulation with experimental data and of operation of the Project eolic.

Problem Description

Ecuador has with wind power projects in some parts of the country, the current project and of higher power generation is Villonaco wind farm located in Loja province south of the country, this being the highest of its kind not only in Ecuador but also globally and also is located in complex terrain, which justifies the need for a characterization study of wind flow, with the help of a software that manages the dynamics of fluids.

Methodology of simulation

Creation of the geometry and domain of the knoll with Inventor (parallelepiped).

Importing geometry with ANSYS-FLUENT.

Creation of geometry planar and meshing of knoll with component "Mesh ".

Independent analysis of meshing in the surface and the profile of the knoll.

Ingress of the boundary conditions and emplacement data.

Numerical Simulation of the knoll.

Analysis of wind potential.

Process

• Collect characteristic data of emplacement.

• Manipulate the parameters of the area and its respective data, for introduce them in the simulation model in the software of engineering and thereby obtain results of wind speed and turbulence values .

• Perform the simulation and modeling of wind flow with the software ANSYS-FLUENT, appropriate for problem solving of fluid and of heat transfer.

• Effect the validation of process used, in accordance a own measurements and scientific studies that have been conducted in other projects of different authors.

• Compare the simulation results with the results and operating data Villonaco wind farm.

Creation of the geometry and domain.

Creation of geometry planar and meshing.

Ingress of the boundary conditions and emplacement data.

Numerical Simulation of the knoll.

Obtain of results

Analysis of wind potential.

Analysis of wind potential.

Energía cinética turbulenta en la cima de la loma X/D = 0. Perfil de velocidades en la cima de la loma X/D = 0.

Validation

One time elaborated computational numerical simulation of the problem presented, it is necessary to perform a validation of method developed, to be certain that what was reported by the specialized software was really a rough prediction of the actual behavior of the wind farm operation method. The validation is performed making a new simulation, this time with a standard knoll which possessing scientific studies with different procedures to the exposed out in this project.

Validation

The standard knoll for the present study is the Askervein hill located in Scotland.

Validation

Validation

A-A AA-AA

Validation A-A

Validation AA-AA

Comparison

Once generated the mesh, set the boundary conditions, performed numerical simulation and obtained the resulting values in the process, we proceed to compare the results of wind speed and power with the operating data registered in the Wind Farm Villonaco , for know the goodness of ANSYS software in the development of the wind problem.

Speed Comparison

Because the speed measurement records for Villonaco wind farm were elaborated with regularly to heights of 30 and 40 meters, analysis and comparison is done with these data. Thus the speeds obtained are:

Height Speed

489 m (30 m) 9,8 m/s

499 m (40 m) 9,7 m/s

Speed Comparison

Of the Records of speeds wind of farm wind , is obtained the following speeds:

Meses 30 m 40 mEnero 7,3 m/s 7 m/s

Febrero 8,9 m/s 8,8 m/sMarzo 11,4 m/s 11 m/sAbril 9,1 m/s 8,7 m/sMayo 13,1 m/s 12,6 m/sJunio 18,6 m/s 17,7 m/sJulio 15,1 m/s 14,5 m/s

Agosto 20,5 m/s 20,1 m/sSeptiembre 14,6 m/s 14,4 m/s

Octubre 7,8 m/s 7,9 m/sNoviembre 6,8 m/s 7,1 m/sDiciembre 6,6 m/s 6,6 m/s

Velocidad Promedio anual 11,65 m/s 11,37 m/s

Comparison of turbulence

Obtaining turbulence intensities to 30 and 40 meters high, are:

AlturasIntensidad

Turbulencia489 m (30 m) 18 %499 m (40 m) 14 %

Comparison of turbulence

Based on average of velocity values measured monthly over the course of a year, will be developed the following expression:

The standard deviation obtained at 30 and 40 meters using a statistical treatment of ENERSUR EP is 0.88 m / s. Therefore, the turbulence intensity obtained in 30 m to 11.65 m/s, is:

Similarly, is performed the same procedure of calculating for the height of 40 m, whose value of speed is 11.37 m / s.

𝐼𝑢=𝜎𝑢=

0,88𝑚 /𝑠11,65𝑚/𝑠=0,0755=7,55%

𝐼𝑢=0,88𝑚/ 𝑠11,37𝑚 /𝑠=0,0774=7,74 %

𝐼𝑢=𝜎𝑢=

𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛 (𝑚/ 𝑠 )𝑎𝑣𝑒𝑟𝑎𝑔𝑒𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 (𝑚/𝑠 )

Power comparisonWith the value of resultant velocity, we proceed to perform the construction of the power curve for get the power supplied by the wind turbine. The construction of the curve need some parameters to solve the following expression:

Where:

The above parameters are own of the site for the wind farm Villonaco and of simulation. The Using them to solve the formula of power, generate a set of points that when put together establish the called power curve for different speed ranges.

Wind density at the emplacement: 0,923 kg/m³Swept área of rotor: 3848,45 m²

Wind speeds: 0, 1, 2, 3……30 m/sPower coefficient: 0,52

𝑃=12 ·𝐶𝑝 · 𝜌 ·𝐴 ·𝑈

3

Power comparison

0 5 10 15 20 250

200

400

600

800

1000

1200

1400

1600

Velocidad (m/s)

Pote

ncia

(kW

)

0 5 10 15 20 250

200

400

600

800

1000

1200

1400

1600

1357.50773890601

1460.28860436675

Velocidad (m/s)

Pote

ncia

(kW

) Of register 30 metros 40 metros

Average Speed(m/s)

11,65 11,37

Power(kW)

1460288,60 1356314,15

Of Simulation 30 metros 40 metros

Average Speed(m/s)

9,8 9,7

Power(kW)

869,238 842,900

Comparison

Description Simulation Data Measured data DifferenceHeight (m) 30

Annual Avg speed (m/s) 9,8 11,65 1,85Annual Power (kW) 869,238 1460,288 591,049

Record (Hrs) 4206,73Annual energy (kWh) 3,66E+09 6,14E+09 2,49E+09

Turbulence Intensity (%) 18 7,55 6,45

Description Simulation Data Measured data Difference

Height (m) 40Annual Avg speed (m/s) 9,7 11,37 1,67

Annual Power (kW) 842,900 1357,507 514,607Record (Hrs) 4206,73

Annual energy (kWh) 3,55E+09 5,71E+09 2,16E+09Turbulence Intensity (%) 14 7,74 10,26

Conclusions:

• Ecuador has many important renewable energy resources for benefit the local economy and the environment, particularly the wind is the resource that has been come using for power generation, same which has had tremendous growth in Ecuador and worldwide , being a very good alternative to reduce the use of fossil resources.

• The wind farm Villonaco due which to is situated at a big height above sea level and has a complex terrain, obtained a large influence of the wind, therefore it is ideal for applying the model of turbulence k-epsilon, the which assumes that the flow is fully turbulent, and despises the viscosity effects.

Conclusions:

• For the simulation, the size finest of mesh refinement in the profile of the knoll is very important because it is where the boundary layer is located and therefore the most significant changes in wind speed occur. Of such a way, which according to the quality of refinement that is applied in the meshing, can affect notably in the accuracy of the problem and results.

• The software validation was performed using as a reference the knoll Askervein located in Scotland, by entering the boundary conditions of the place, and obtaining results comparative very acceptable, namely the velocity values of the simulation are approaching to those recorded in the different points of the knoll.

Conclusions:

• By locating the simulation results performed in the ANSYS FLUENT software in the velocity profile is obtained as the result that the speeds are very similar to those values recorded at the emplacement .

• The turbulence intensity recorded at the emplacement compared to the turbulence intensity resulting from the simulation are not similar because the standard deviation depends on the values of record of speed, of which are variables in the course of measurements taken year to year.

Conclusions:

• The potencies obtained from 0.8 MW and 1.3 MW, starting from the resulting speed of the simulation is an acceptable value because the guaranteed power of 1.5 MW in the Villonaco windfarm is assumes in ideal conditions namely, that always have velocity values between 12 and 25 m/s, and is something that really can not be achieved, because the wind speed is variable during a given time, provoking the oscillation of its values.

• The results obtained by the simulation with the model used, are very close to the values which resulting from the data of records. Based on these good results are achieved affirm that the behavior of the wind flow in the Villonaco wind farm is described in a very rough way by the different values , graphs, contour, etc., whom were were extracted of post-processing of simulation.

Recommendations:

• Projects resulting from this study, require sufficient knowledge about the turbulence models, basic management and medium of ANSYS FLUENT and the boundary conditions of the study area.

• At the time of perform the meshing of the knoll, should be take into account which; if the meshing is very coarse, the values which is obtain, they'll be away from the actual data, and if it is too fine, the convergence were not will perform by excessive set of tetrahedra, causing a convergence error. Therefore, the meshing must adequately capture the characteristics of the knoll. For this, you must perform the tests necessary to have a criterion correct of meshing and the subsequent obtaining of the results.

Recommendations:

• Projects resulting from this study, require sufficient knowledge about the turbulence models, basic management and medium of ANSYS FLUENT and the boundary conditions of the study area.

• For future projects is recommended to analyze the possibility of perform the same study of operation, with a threedimensional simulation, to interpret and compare the results presents in two dimensions with the that can be obtained in three dimensions.

Recommendations:

• Once it has been possible to determine the behavior of the wind flow through simulation and obtaining the velocity profile; is considered necessary to study in depth the impact it could have on other locations inside and outside the country, the velocities and turbulence that occur in emplacement where be want to implement wind projects.