What is the model selection?
During the construction of wind farms, the selection of wind turbines is constrained by conditions such as the natural environment, transportation, and lifting. At the same time, the choice of wind turbines determines the investment in construction and power generation, and the selection of wind turbines 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 wind farms, economically viable wind power generating units are selected to calculate the annual power generation capacity of the wind farms, and the wind power generating unit with the best comprehensive index is selected.
The selection of wind turbines not only affects the amount of investment in wind farms, but also affects the amount of power generation and operating costs after production, and ultimately affects the on-grid tariff. Therefore, in the investment in fixed assets of wind power projects, the selection of wind turbines is of great significance.
Basic principles and main requirements for model selection
(a) Basic principles
First of all, the cost performance ratio is optimal, that is, the wind turbines with the best performance and quality are purchased at the lowest price.
Secondly, with the minimum cost of power generation as an indicator, the efficiency of generator inputs and outputs should be fully considered. In some special cases, if the power generation of the wind turbines is not much different, when selecting a wind turbine, it is necessary to consider whether the maximum capacity factor can be converted into the largest capacity factor.
(b) Requirements
1, quality certification. The wind turbine manufacturing must have ISO9001 quality assurance system certification, which is the most fundamental guarantee system to guarantee the normal operation and maintenance of wind farm units.
2. Unit power curve. Power curve is one of the most important curves reflecting the output performance of wind turbines.
3, the manufacturer's performance. Performance is one of the important indicators for judging the level of a wind power manufacturing company.
4, special environmental requirements. Typhoon, low temperature, thunderstorms, dust and other special environments will affect the wind turbines, so in these special circumstances, various requirements are put forward for wind turbines.
The 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, limit 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 indicators of wind turbines. The closer the rated wind speed is to the annual average wind speed of wind farms, the closer the wind turbines are The higher the full-rate electricity generation rate.
The other is the limit wind speed. It is mainly related to the safety of wind turbines. If the wind speed of the wind farm exceeds the limit wind speed of the wind turbine, the wind turbine may be damaged. However, blindly pursuing safety and inappropriately selecting wind turbines with extreme wind speeds will increase investment without any sense. Because the wind turbine is in the state of full power generation between the rated wind speed and the cut-out wind speed, choosing a product with high wind speed is beneficial to multi-generation. However, in order to increase the control of the wind speed from the rated wind speed to the cut-out wind speed, the products with high wind speed must be increased. Investors must consider the pros and cons of the wind energy resources of the wind farm.
Followed by factors related to the type and capacity of wind turbines. The main types of wind turbines can be divided into fixed pitch and variable pitch, passive stall and active stall, constant speed constant frequency and variable speed constant frequency. In addition, with the increase or decrease of the stand-alone capacity of wind turbines, the cost per kilowatt will increase to some extent. The diameter of a wind turbine, the height of a tower, and the weight of a unit of a unit with a large stand-alone capacity will increase, resulting in an increase in the cost of the unit.
Once again, consider the low-voltage ride-through capability of wind turbines. Low-voltage ride-through refers to the ability of a wind turbine to maintain normal operation without stopping when an instantaneous, certain-level voltage drop occurs in the power grid due to various reasons. Wind turbines with poor low-voltage ride-through have a protective shutdown when the grid voltage drops and automatically cut out the grid. Cutting out a grid from a wind turbine will lead to a further drop of the grid voltage, resulting in total downtime of the whole wind turbine, 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 and directly affects the selection of wind turbines.
The last is economic factors. Including the on-grid price, investment in fixed assets and equipment utilization, as well as the impact of wind turbines transportation, lifting and maintenance.
Wind turbine selection
The selection of wind turbines is divided into single capacity selection and model selection.
1, single capacity selection
According to the current status of the domestic and foreign fan market and the installed capacity of domestic wind farms, the fan can be divided into four levels according to the size of the single machine.
1600kW class unit
The stand-alone capacity is 600kW or 750kW, suitable for installation on wind farms with complex terrain. Such foreign units have begun to withdraw from the fan market. Domestic manufacturers of this level of wind turbines include Xinjiang Goldwind and Zhejiang Yunda.
2850kW unit. Single machine capacity is between 850kW and 1000kW. The technology of this type of unit is mature and has good performance. It is suitable for wind farms with poor site conditions and transportation difficulties. There is still a certain space and potential in the market. Wind turbines of this class are installed in large numbers in China.
3MW class unit. Stand-alone capacity is between 1MW and 3MW. This type of unit is relatively mature in technology. At present, the 1.5~2MW class units in China have become the mainstream mature models. The 3MW class units have achieved mass production and the performance has grown rapidly. Goldwind and other manufacturers are Stepping up the pace of launching 5MW and 6MW models, Huarui, Mingyang and Guodian United Power 6MW models have been installed with prototypes. Huarui, Xiangdian, Haishang have installed 5MW prototypes, and will gradually accumulate practical experience and step into batch production. Production stage.
More than 4 MW class units. The components of this type of fan are extremely long and heavy, and it is difficult to transport and hoist. Currently, there are a certain number of installations in developed countries such as Europe and the United States, which are mainly installed in offshore wind farms and have not yet been put into commercial operation on a large scale.
2, the choice of models
In the field of wind power technology, the type of fan is mainly differentiated according to the different adjustment technologies. The current fan market mainly consists of two types: pitch and pitch. Pitch adjustment technology mainly includes: slip, pitch, variable speed, variable frequency and double feed. The fixed-pitch fan has a simple structure, a simple adjustment method, a strong and firm structure, and a large number of small and medium-sized units, suitable for installation in wind farms with relatively complex wind conditions.
The variable pitch is lighter than the pitched fan structure, and the structure is complex. It can be adjusted according to the change of wind speed to obtain more power. Most of the MW-class turbines use pitch, speed, and double feed. Each regulation technique represents a different type of fan and has its own characteristics. It is suitable for different wind farm conditions, and there are no pure advantages or disadvantages.
At present, wind turbines are rapidly developing toward large-scale and high-efficiency. After several decades of development, grid-connected wind turbines have basically eliminated some models that are impractical, technically flawed or have no commercial value, forming the most common horizontal axis, 3-blade, upwind, and tube type. The unified model of the tower.
The technical, practical and economical characteristics of wind turbine selection
1. The technical characteristics of the selection of wind turbines
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
In the construction of wind farms, wind resources assessment must first be performed on the selected wind farms. At present, testing and evaluation of wind resources at home and abroad have developed many test equipments and evaluation softwares. Commercialized software has been developed for site selection of wind farms, especially for microscopic site selection, such as WASP, a resource analysis tool for microsite selection of wind farms developed by Danish RIS National Research Laboratory, and meteodyn WT developed by Meidi, France. Wait. There are also similar domestic software, such as electric field design and optimization software WINDFARMER, making wind resources have a certain degree of protection in the evaluation, providing an important basis for the next choice of single-machine capacity.
2 wind power calculation
According to the assessment results of wind resources, determine the annual average wind speed and annual wind power density, determine whether the prevailing wind direction of the wind farm is stable, the turbulence intensity is small, and the measured air density and wind shear index, wind power density in the field Wait. According to "Wind Power Resources Assessment Method for Wind Power Plants" (GB/T18710-2002), qualitative wind farms belong to which type of wind farms, so that high-efficiency fans suitable for the wind farms are selected for the selection of wind power generators.
3 Estimated on-grid electricity
According to several types of models suitable for the wind farm, the annual theoretical power generation amount should also be calculated. That is, according to the power and thrust coefficient curve of the wind field in the standard state, the arrangement of the wind turbine and the topographic map of the wind farm, the theoretical power generation under the standard state is calculated by using a program. Then consider the correction of air density, wake correction, control and turbulence reduction, blade pollution reduction, power curve reduction, plant power, line loss and other energy loss and climate impact shutdown and other factors, estimate the current wind farm project year Internet power.
4 Unit reliability
The reliability of the unit refers to the degree of reliability of the unit's stable operation, which is proposed considering the structure and composition of different models. In addition, the reliability is also related to the quality of the components selected by the unit equipment, production quality and installation quality.
2. Practicality of selection of wind turbines
The practicality of the selection of wind turbines mainly refers to the fact that depending on the characteristics of the wind farm, considering the unit selection will also be constrained by the natural conditions of wind farms, transportation, lifting and other conditions. At the same time, the overall planning and scale of wind farms must also be considered, combined with the technical nature of the selection, so as to decide on the selection of practical types of units.
3, the economics of the selection of wind turbines
The economics of the selection of wind turbines mainly refer to the evaluation of the economic benefits of the wind farm investment. For a wind power project, the main risk variables are investment in fixed assets, annual on-grid electricity, and on-grid tariffs. Under the situation that the grid electricity price is temporarily uncertain, due to the large fluctuation in the price of wind turbine equipment, the issue of investment return on wind power projects has become a major factor affecting the investment in wind power projects. Therefore, in the case of a given grid price, for the construction and investment of a wind farm, it is necessary to consider factors such as the cost per unit of kilowatts, annual on-grid power generation, and internal fund yield. Through the calculation, comparison and analysis of various schemes for the construction of wind farms, economic indicators that can reflect each scenario are drawn.
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