ارزیابی و پهنه‌بندی پتانسیل سرعت باد در کشور به‌منظور برنامه‌ریزی جهت تولید برق بادی

Introduction
Wind has long been considered and used by humans as the oldest source of energy. The conversion of wind energy and the energy extraction have been carried by humans since the ancient times, and since about 5000 BC, wind power has been used to navigate the Nile. At present, over 83 percent of wind power is used in only five countries of the world including Germany, the United States, Denmark, India and Spain.  Therefore, most of the wind energy knowledge can be found in these countries, yet the use of wind energy technology is expanding rapidly to other areas of the world, and the information needed is extended throughout the world (Patel et al., 1999). The energy crisis, in particular that of  oil, and air pollution, are the issues that will require the continuation and strengthening of meteorological and climatological studies in search of new sources of clean energies. The most important of these sources are solar and wind energy. Of course, in the design of energy conversion tools, there should also be considered the type of use and storing it. Today, energy is being developed through electric grids, static generating motors (diesel, gasoline or hybrid), hydropower, fossil fuels, and gas-powered plants, generators and wind turbines, and other newly developed technologies. In a paper titled Wind Turbines and Wind Power Potential Assessment in Iran, while studying the types of wind turbines and the amount of wind energy and the speed required to produce wind power, using the five- year wind data (1981 to 1985) in the country's synoptic stations, Kaviani (1995),    evaluated the potential of wind energy in Iran and concluded that in the whole country, Zabol station (Sistan region) has the best conditions for the construction of wind farms. Ghahreman and Ghareh Khani (2010), also investigated the process of time variation of wind speed in 40 synoptic stations of Iran during 1975-2005 with two nonparametric methods of Man Kendal and Spearman coefficient and two parametric methods of regression and Pearson correlation coefficient, in annual and seasonal scale. Bakhtiari et al. (2013) examined the wind energy potential based on short-term 10-minute data in Kerman, Jiroft, and Bam areas using probability distribution and density function calculations. Roshan et al. (2014) investigated the potential of wind energy at selected Iranian stations and concluded that Zabol, Ardebil and Kish stations had the highest wind power at 3042, 1675 and 1092 watts per square meter, respectively, among stations studied.
Wan and et al. (2010) examined the wind speed near the ground level of 117 stations in Canada; the results showed that the wind speed in the western parts of Canada and most of its southern parts was decreasing in all seasons, but in the central and northern parts in all seasons and in marine areas, there is an increasing trend in the spring and autumn seasons. Bilal et al. (2013) examined the feasibility of using wind energy to generate electricity on the coast of western Senegal, and estimated wind power density in the area to be between 30 and 120 watts per square meter.
In this research, we tried to identify suitable locations for wind turbines in the country by studying the wind variable in the country. Therefore, this study aimed to identify the windy regions of the country and the potential of wind energy.
Materials and methods
 In this study, the three- hour wind speed and direction in synoptic stations of the country were used to study the wind energy in the country. At first, the wind speed and direction statistics were surveyed for 183 stations in the country at three –hour frequency  (hours 00, 03, 06, 09, 12, 15, 18, and 21, based on GMT), and according to the required time period (twenty years from January 1, 1991 to December 31, 2010,) 145 stations were selected with full-time statistics for the entire period, and then the average wind speed and wind power potential and   probability of suitable speed winds for wind power usage (About 8 knots or 4 m / s and more) were calculated. In order to identify windy regions in the country for wind power generation, cluster analysis was used in SPSS software. Finally, the potential wind energy in the windy regions of the country was calculated according to the following equation:
Results and discussion
According to a cluster analysis on wind speed data in 145 synoptic stations of the country, the stations in the country were classified according to the wind speed into five main categories.
The first group consists of three stations, Manjil, Nehbandan and Zabol, which are very suitable for wind power use to produce electrical energy in most days and months in that the average annual wind speed at these stations is about 10.55 knots.
The second group includes stations of Abadan, Aligudarz, Ardebil, Ardestan, Bandar Dir, Bandarlangeh, Mahshahr, Bijar, Bostan, Borujerd, Qorveh, Jask, Qeshm, Kish, Kahnuj, Khoramdareh, Nain, Sabzevar, Torbat Jam, Zahedan, and Zarina Obato. Which also have the potential of wind energy to produce electric energy in some months of the year or at some times of the day. This makes it possible to place them in the appropriate category. The average annual wind speed in these areas is about 7.2 knots.
The third group includes the stations of Ahar, Baft, Bam, Bandar Abbas, Biarjamand, Birjand, Bushehr, Chahbahar, Nojeh Hamedan, Kangan Cham, Kerman, Khash, Khodabandeh, Malayer, Marahtepeh, Ravansar, Rabat Pashtbadam, Saravan, Sardasht, Shahrbabak, Reza shahr, Tehran, Shoshtar, Tabriz and Yazd, which are not very suitable for wind power generation in terms of wind potential, and the annual average wind speed in these areas is about 5.6 knots.
The fourth and fifth groups include stations with an average annual wind speed of less than 4 knots in these areas, not having the potential to produce electric energy from wind.
 
Regarding the importance of wind speed continuity to move wind turbines, the percentage of wind speed frequency   in windy stations of the country was also studied and ranked in five categories. The first rank includes stations where the frequency of winds of more than 4 m / s over the year is well above 40%, which only includes the Manjil station. The second rank relates to stations where the frequency of winds at speeds of more than 4 m / s during the year is between 30 and 40%, including Zabol, Torbat Jam and Bandar Dir stations. The third rank goes for the stations with frequency of winds of more than 4 m / s between 20% and 30%, while the fourth rank belongs to the stations with an frequency of winds of more than 4 m / s between 10% and 20%, and the fifth rank is allocated to the station with frequency of wind speed exceeding 4 m/s less than 10%. Finally, based on the calculations performed on wind data, it was found out that the highest wind energy potential in the country with a value of over 1500 J / m 2 is in the region of Manjil and Zabol.  Followed by these stations is  Nehbandan area with values ​​between 1,000 and 1,500 J per square meter, ranking the second highest wind power potential in the country to produce wind energy. The third rank in terms of the potential of wind energy in the country with the values ​​of 500 to 1,000 J / m2 is related to the stations of Mahshahr, Bijar, Torbat Jam, Jask, Kish, Khoramdareh, Aligudarz, Ardestan and Ardabil stations, which also have the potential for launching  wind turbines to produce  wind energy.
Conclusion
  Iran is rich in renewable and non-renewable energy sources. The geographic location of Iran has caused a huge source of solar and wind to exist all over the year. These two renewable energy sources are free and environmentally friendly, and wind energy can produce a significant amount of electrical energy. The eastern part of Iran, from the south east to the northeast, is the windiest region of the country, and in most cases it has wind power production capacity. Thereafter, Khuzestan plain, islands and coasts of the Persian Gulf and Oman Sea, the western regions of the country in the provinces of Kurdistan, Kermanshah, Lorestan and Hamedan, and small and scattered areas including: Manjil, Ardebil, Firouzkooh, Rafsanjan and Ardestan, posses the capacity of wind energy production in many months of the year. Wind power. Most of the country's windy regions are deprived, arid and less developed regions, with low levels of electrical energy production, and the cost of bringing electricity to these areas is also of high costs. Therefore, creating wind farms in these areas is a necessity. Most of the energy consumption in Iran is in the summer in order to cope with the warmth, and the windiest time in Iran is summer.