What is the model selection?
In the process of building a wind farm, the choice of wind turbines is subject to conditions such as natural environment, transportation, and hoisting. At the same time, the choice of wind turbines determines the investment and power generation of the construction site. The selection of the wind turbine is to choose the best fit between the two. Under the premise of advanced technology and reliable operation, according to the wind energy resources of the wind farm, select economically feasible wind turbines, calculate the annual power generation of the wind farm, and select the wind turbine with the best comprehensive index.
The selection of wind turbines not only affects the investment in wind farms, but also affects the amount of power generation and operating costs after commissioning, and ultimately affects the on-grid price. Therefore, in the fixed asset investment of wind power projects, the selection of wind turbines is of great significance.
Basic principles and main requirements for model selection
(1) Basic principles
First of all, the performance price ratio is optimal, that is, the wind turbine generator with the best performance and quality is purchased at the lowest price.
Secondly, taking the minimum power generation cost as an indicator, fully consider the benefits of generator input and output. In some special cases, if the power generation of each wind turbine is not much different, then the wind turbine should be selected to consider whether it can be converted to the maximum capacity factor with the minimum power generation cost.
1. Quality certification. Wind turbine manufacturing must have ISO9001 quality assurance system certification, which is the most fundamental guarantee system for ensuring the normal operation and maintenance of wind farm units.
2. Unit power curve. The power curve is one of the most important curves reflecting the performance of wind turbine generator output.
3. Manufacturer's performance. Performance is one of the important indicators for judging the level of a wind power manufacturing enterprise.
4. Special environmental requirements. Special environments such as typhoon, low temperature, thunderstorm, and dust will affect wind turbines. Therefore, in these special circumstances, different requirements are imposed on wind turbines.
Main factors affecting the selection of wind turbines
The first is the factors related to wind energy resources. It mainly includes several important indicators such as rated wind speed, ultimate wind speed and cut-out wind speed. The difference in output of different wind turbines is mainly concentrated in the interval below the rated wind speed. Therefore, the determination of the rated wind speed is directly related to the output index of the wind turbine. The closer the rated wind speed is to the annual average wind speed of the wind farm, the wind turbine The full load generation rate is higher.
The other is the limit wind speed. It is mainly related to the safety of wind turbines. If the ultimate wind speed of the wind farm exceeds the limit wind speed of the wind turbine, the wind turbine may be destroyed. However, if blindly pursuing safety and improperly selecting wind turbines with extreme wind speeds, it will increase investment insignificantly. Since the wind turbine is in a full-power generation state from the rated wind speed to the cut-out wind speed, it is advantageous to cut off the product with high wind speed to facilitate multi-generation. However, it is necessary to increase the input of the product with high wind speed in the control of the rated wind speed to the cut-out wind speed. Investors must comprehensively consider the advantages and disadvantages according to the characteristics of the wind energy resources of the wind farm.
This is followed by factors related to wind turbine type and capacity. The main types of wind turbines can be divided into fixed pitch and pitch, passive stall and active stall, constant speed constant frequency and variable speed constant frequency. In addition, as the single unit capacity of the wind turbine increases or decreases, the cost per kilowatt will increase to some extent. The wind turbine diameter, tower height, and equipment weight of a unit with a large single unit capacity will increase, resulting in an increase in unit cost.
Again consider the low voltage ride through capability of wind turbines. Low voltage ride through means that when the grid has a transient, certain amplitude voltage drop for various reasons, the wind turbine can continue to maintain normal operation without stopping. Wind turbines with poor low-voltage ride-through capability will have a protective shutdown and automatically cut out the grid when the grid voltage drops. A wind turbine cuts out of the grid and causes the grid voltage to fall further, causing the entire wind turbine to shut down completely, eventually leading to The grid collapsed. Therefore, the low voltage ride-through capability of wind turbines is an important indicator to measure the grid-connected performance of wind turbines, which directly affects the selection of wind turbines.
Finally, the economic factor. It mainly includes on-grid tariffs, fixed asset investment and equipment utilization, as well as the impact of wind turbine transportation, hoisting and maintenance.
Wind turbine selection
The selection of wind turbines is divided into single capacity selection and model selection.
1, single machine capacity selection
According to the current status of the domestic and international wind turbine market and the installed capacity of domestic wind farms, the fans can be divided into four levels according to the capacity of the single machine.
1600kW class unit
With a stand-alone capacity of 600kW or 750kW, it is suitable for installation in wind farms with complex terrain. Such foreign units have begun to exit the wind turbine market. The domestic manufacturers of this level of wind turbines include Xinjiang Goldwind and Zhejiang Yunda.
2850kW class unit. The single unit capacity is between 850 kW and 1000 kW. These units are mature in technology and have good operating performance. They are suitable for wind farms with poor site conditions and difficult transportation. There is still room and potential in the market. This level of wind turbines is installed in large numbers in the country.
3MW class unit. The unit capacity is between 1MW and 3MW. These units are relatively mature in technology. At present, China's 1.5~2MW units have become mainstream mature models, and 3MW units have achieved mass production. The performance has grown rapidly. Stepping up the pace of launching 5MW and 6MW models, the prototypes of Huarui, Mingyang and Guodian combined power 6MW models have been installed, and Huarui, Xiangdian, and Haizhuang have installed 5MW prototypes, which will gradually accumulate practical experience and step into batch production. Production stage.
4 multi-MW class units. The components of this type of fan are ultra-long, overweight, and difficult to transport and hoist. Currently, there are a certain number of installations in developed countries such as Europe and the United States, mainly installed in offshore wind farms, and have not been put into commercial operation on a large scale.
2, the choice of model
In the field of wind power technology, the types of fans are mainly differentiated according to their different adjustment technologies. In the current fan market, there are two main types: fixed pitch and variable pitch. The pitch adjustment technology mainly includes: slip, pitch, variable speed, frequency conversion and double feed. The fixed pitch fan has simple structure, simple adjustment mode, firm and firm structure, and is used by small and medium-sized units. It is suitable for installation in wind farms with relatively complicated wind conditions.
The pitch is lighter than the fixed pitch fan structure, and the structure is complicated. It can be adjusted according to the change of wind speed to obtain more power. Most of the MW-class units use pitch, variable speed, and doubly-fed technology. Each adjustment technology represents a different type of fan, and has its own characteristics, suitable for different wind farm conditions, there is no pure advantage.
At present, wind turbines are rapidly developing in the direction of large-scale and high-efficiency. After several decades of development, the grid-connected wind turbines have basically eliminated some models that are not practical, technically flawed or not of commercial value, forming the most common horizontal axis, 3-blade, upwind, and tubular The unified mode of the tower.
Technical, practical and economical selection of wind turbines
1. Technicality of wind turbine generator selection
The technical characteristics of wind turbine selection are mainly reflected in the following aspects: wind resource assessment; wind power calculation; on-grid electricity estimation; unit reliability.
1 Wind resource assessment
Wind farm construction, first of all, the wind resource assessment of the selected wind farm. At present, many testing equipment and evaluation software have been developed for testing and evaluation of wind resources at home and abroad. Commercial software has been developed for wind farm site selection, especially for micro-site selection, such as WASP, a resource analysis tool developed for the micro-location of wind farms developed by the Danish RIS National Research Laboratory; meteodyn WT developed by France Medic Wait. There are similar softwares in China, such as the electric field design and optimization software WINDFARMER, which makes the wind resources have certain guarantees during the evaluation, which provides an important basis for the selection of the next-machine capacity.
2 wind power calculation
According to the conclusion of wind resource assessment, determine the annual average wind speed and annual wind power density of the wind farm, and further determine whether the wind direction of the wind farm is stable, whether the turbulence intensity is small, and the measured air density and wind shear index and wind power density in the field. Wait. According to the "Wind Power Plant Wind Energy Resource Assessment Method" (GB/T18710-2002), it is qualitative which wind field belongs to the wind farm, so that the high-efficiency wind turbine suitable for the wind farm is selected in the wind turbine selection.
3 estimation of online electricity
According to several types of models suitable for the wind farm, the calculation of the annual theoretical power generation is also required. That is, according to the power and thrust coefficient curves of the wind field under standard conditions, the arrangement of the wind turbine and the topographic map of the wind farm, the theoretical power generation in the standard state is calculated by a program. Then consider the air density correction, wake correction, control and turbulence reduction, blade pollution reduction, power curve reduction, plant power, line loss and other energy losses and climate impact shutdown, etc., estimate the wind farm engineering year Internet power.
4 unit reliability
The reliability of the unit refers to the reliability of the stable operation of the unit considering the structure and composition of different models. In addition, reliability is also related to the quality, production quality and installation quality of the components selected for the unit.
2. Practicality of wind turbine generator selection
The practicality of wind turbine selection mainly refers to the constraints of the wind farm's natural conditions, transportation, and hoisting according to the characteristics of the wind farm. At the same time, we must also consider the overall planning and scale of the wind farm, combined with the technical nature of the selection, and thus decide to use a practical type of unit.
3. Economics of wind turbine selection
The economics of wind turbine selection mainly refers to the evaluation of the economic benefits generated by the investment in the wind farm. For a wind power project, the main risk variables are fixed asset investment, annual on-grid electricity and on-grid electricity prices. In the case that the grid price is temporarily uncertain, due to the large fluctuations in wind turbine equipment prices, the wind power project investment return problem has become a major factor affecting wind power project investment. Therefore, in the case of grid price given, for the construction and investment of a wind farm, it is necessary to consider the cost of the unit kilowatt, the annual on-grid power generation and the internal rate of capital. Through the calculation, comparison and analysis of various schemes for wind farm construction, economic indicators that reflect each scheme are obtained.