A design method for a hybrid deicing system based on wind turbine blade icing characteristics

Abstract

The present invention discloses a design method for a hybrid deicing system based on the icing characteristics of wind turbine blades, which belongs to the field of wind power generation technology. Combined with the actual situation of wind turbine blades, based on wind tunnel icing tests, the time and space development characteristics of blade icing are obtained, and a database of the areas and thicknesses where icing appears and grows in different time periods is established. Combined with the icing characteristics of blades under different freezing levels of weather, in areas not prone to icing, areas where only the gas-heat deicing method is used to solve the blade anti-icing needs are comprehensively screened out, while the remaining areas are assisted by the electric heating anti-icing method; at the same time, the rated power of the electric heating film is customized according to the difference in blade icing intensity. After the system is put into operation, combined with the icing characteristics database and icing monitoring, under different freezing weather conditions, only the gas-heat deicing system is operated or the hybrid deicing system of gas-heat + electric heating is comprehensively controlled, so that the wind turbine blades have efficient anti-icing functions under all climate conditions and low energy consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and in particular relates to a design method of a hybrid deicing system based on icing characteristics of wind turbine blades. Background Art

[0002] Wind farms in southern China, both in low-wind and some high-wind regions, face severe icing problems during winter and spring. Ice accumulation on wind turbine blades alters the blades' aerodynamic shape and weight distribution, disrupting load balance and causing vibrations between the blades and the rotor. This has a direct impact on the economic and safe operation of the turbine and power generation.

[0003] Given the current large base of existing wind power, there is an urgent need for efficient anti-icing technology for wind turbine blades in freezing weather. Currently, anti-icing methods include active methods such as thermal deicing (gas / electric deicing), chemical deicing, and mechanical deicing, as well as passive methods such as anti-icing coatings based on super-hydrophobic coatings.

[0004] At present, there is no mature wind turbine blade anti-icing technology (or combination) that can be widely promoted and applied. In fact, due to the differences in the environment and icing climate conditions of wind turbines, as well as the characteristics of wind turbine blades such as large length and uneven thickness distribution, blade anti-icing technology has different degrees of high energy consumption, short life, high equipment and operation and maintenance costs, and lightning damage. These problems or risks have caused a "bottleneck" in the application of blade anti-icing methods with a single technical route. For example, gas-thermal deicing technology cannot achieve efficient and low-energy deicing effects for the entire blade due to the weak thermal conductivity of the blade material and the difference in thickness distribution; although electric deicing technology does not need to overly consider the problem of heat transfer, it has the risk of lightning strikes (using electric deicing on the entire blade will increase the risk of lightning strikes, etc.); super-hydrophobic anti-icing coatings can only prevent ice, not de-ice, and the anti-icing function of the coating may fail in severe freezing weather, etc.

[0005] Due to the limitations of a single anti-icing technology, wind turbine blades can consider adopting a hybrid anti-icing method. Simply superimposing multiple anti-icing technologies will not only lead to high design, manufacturing, installation and operation and maintenance costs, but also poor de-icing effect and high energy consumption in actual operation. Summary of the Invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a design method for a hybrid deicing system based on the icing characteristics of wind turbine blades, which can enable wind turbine blades to have efficient anti-icing functions under all climatic conditions (including extreme freezing weather), and the system has low construction cost and low energy consumption.

[0007] The present invention is achieved through the following technical solutions:

[0008] A design method for a hybrid deicing system based on the ice coating characteristics of wind turbine blades includes the following steps:

[0009] S1: Collect and analyze environmental and meteorological factors of wind turbines to determine the meteorological parameter combination for blade icing characteristic test;

[0010] S2: Based on the actual blade conditions of the wind turbine, restore and make a blade icing test model;

[0011] S3: In a wind tunnel test facility, based on the meteorological parameter combination determined in S1 and the blade icing test model prepared in S2, combined with the normal operating parameters of the wind turbine, restore the icing environment characteristics of the wind turbine blades; observe the icing characteristics of the blade icing test model to obtain the spatiotemporal characteristics of icing on the blade surface;

[0012] S4: Quantitatively analyze the spatiotemporal characteristics of blade surface icing obtained in S3 to obtain the evolution of blade icing in different time periods after icing begins to form, and obtain an icing characteristics database;

[0013] S5: Based on the icing characteristics database obtained in S4, the blade icing conditions under various typical weather conditions, including extreme icing climates, are selected to comprehensively determine the boundaries of the air-heat deicing area alone and the air-heat / electric-heat hybrid deicing area;

[0014] S6: Design the aerothermal deicing system and optimize its operating parameters based on numerical simulation methods. Then, based on the temperature distribution on the blade outer surface, update and supplement the aerothermal deicing area.

[0015] S7: Install electric heating films in the air-heat / electric-heat hybrid deicing area outside the air-heat deicing area, and customize the rated power of the electric heating films at each location to complete the design of the blade hybrid deicing system.

[0016] Preferably, in S1, the environmental and meteorological factors include wind speed, air pressure, temperature, humidity and particle size distribution of supercooled water droplets in the air.

[0017] Preferably, in S1, the meteorological parameter combination includes main meteorological characteristics that can reflect normal icing weather and extreme freezing weather in which the wind turbine is located.

[0018] Preferably, in S2, the blade condition includes surface material, airfoil, length and surface roughness.

[0019] Preferably, in S3, the icing characteristics include the type, occurrence area and formation speed of blade icing.

[0020] Preferably, S4 is specifically as follows: based on the spatiotemporal characteristics of ice formation on the blade surface obtained in S3, the temporal and spatial development characteristics of the appearance and growth of ice on the blade under different levels of freezing climate are analyzed, the law of ice appearance area and thickness development at different spanwise positions of the blade is obtained, and the critical thickness at which the ice condition deteriorates within a specific time is determined, thereby forming a database of ice characteristics of specific blades under different freezing climates in the environment in which they are located.

[0021] Preferably, S5 is specifically as follows: based on the icing characteristic database obtained in S4, combined with the icing conditions of the blades in various typical icing climates, the boundaries of the gas-thermal deicing area and the gas-thermal / electric-thermal mixed deicing area are comprehensively determined; in extreme icing climates, the position where a specific ice thickness is formed within a preset time after icing begins and the area close to the trailing edge of the blade are selected as the gas-thermal deicing area; the remaining area of ​​the blade is the gas-thermal / electric-thermal mixed deicing area.

[0022] Preferably, S6 is specifically as follows: combining conventional hot air deicing technology, observing the difference in the effect of hot air on blade heating based on numerical simulation methods, adjusting and iteratively optimizing the hot air delivery parameters, so that the blade surface temperature corresponding to the gas-heat separate deicing area is not lower than 0.5-1.5°C, and the maximum heating air temperature does not exceed 70°C; combining the blade outer surface temperature distribution under the optimized hot air delivery parameters, the gas-heat separate deicing area is updated and supplemented.

[0023] Preferably, S7 specifically includes: installing an electric heating film in the gas-heating / electric-heating mixed deicing area other than the gas-heating deicing area, and differentially determining the rated power of the electric heating film based on the temperature distribution of the outer surface of the blade, the internal thermal conductivity of the blade, and the icing characteristics database.

[0024] Preferably, under normal icing climate conditions, based on the icing characteristics database and combined with the icing monitoring system, the operating parameters of the gas-heat deicing system are adjusted to meet the blade anti-icing needs in lighter freezing weather; in more severe or extreme freezing weather, combined with the icing monitoring and icing characteristics database of the electric heating film covering area, the operating power of the electric heating film in each area on the blade is optimized, and the gas-heat deicing system and the electric heat storage system are used to collaboratively remove ice from the blade.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention discloses a design method for a hybrid de-icing system based on the icing characteristics of wind turbine blades. Combined with the formation and development patterns of icing on the target blades, a customized design of an efficient anti-icing system and its operation mode is developed. This design method is significantly different from the hybrid technology that simply superimposes multiple anti-icing technologies on the same blade, and is relatively more technically difficult. This is because the blades are large in size, and the airfoils at different positions in the spanwise direction of the blades have different relative velocities with the incoming atmospheric flow, resulting in differences in the interaction between water vapor or tiny water droplets in the atmosphere and the blades, which directly affects the icing process, causing the formation and development process of icing on the entire blade to exhibit certain regularities and differences. Designing a hybrid anti-icing system based on this regularity has advantages in reducing equipment requirements, reducing system energy consumption, and reducing lightning protection risks.

[0027] The present invention comprehensively selects areas with lower ice levels on the upper and lower surfaces of the blades, and relies on the optimization of the operating parameters of the gas-thermal deicing system to achieve the anti-icing effect; in the remaining areas with higher ice levels, the blade tips and other places are relatively thin, and the operation of the gas-thermal deicing system can achieve partial deicing effect, and the remaining areas comprehensively consider the contribution of the gas-thermal deicing system and the severity of ice, assisted by the covering of the electric heating film, and can quantitatively select the rated power of the electric heating film, to achieve customized design for the anti-icing needs of the entire blade, thereby solving the anti-icing needs of the wind turbine blades in freezing weather of different degrees in the specific environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0030] like Figure 1 The present invention's hybrid deicing system design method based on wind turbine blade icing characteristics begins by collecting and organizing environmental and meteorological factors (including but not limited to wind speed, air pressure, air temperature, humidity, and the particle size distribution of supercooled water droplets in the air) for the specific wind turbine for which the hybrid anti-icing solution is designed. Combined with historical extreme weather conditions when the wind turbine blades experienced the most severe freezing, multiple meteorological parameter combinations are selected and designed for blade icing characteristic testing. The selection and design of these meteorological parameter combinations must reflect the primary meteorological characteristics of both normal and severe (extreme) freezing weather conditions within the turbine.

[0031] Secondly, based on the blade conditions of the target wind turbine for anti-icing and de-icing modification (such as surface material, airfoil, length, surface roughness, etc.), an identical blade icing test model is restored and produced;

[0032] Then, in the blade icing wind tunnel test facility, based on the above-mentioned meteorological data settings and test blade design, combined with the normal operation of the wind turbine (such as speed, etc.), the icing environment characteristics of the wind turbine blades are set and restored.

[0033] Blade icing tests were carried out to observe the icing characteristics of wind turbine blades, including the type, occurrence area, and formation speed of blade icing, and to obtain the spatiotemporal characteristics of icing on the blade surface, that is, the appearance and development characteristics of icing over time.

[0034] A quantitative analysis of the test results, combined with existing icing theory, shows that ice primarily forms at the blade tip and the leading edge of the mid-to-back section of the blade. This is because the blade tip and the incoming air flow have a greater relative velocity, and tiny supercooled water droplets in the air collide with the faster-moving blade, making them more likely to undergo a morphological change, transforming into a solid state and adhering to the collision zone to form ice. The leading edge of the mid-to-back section of the blade is more susceptible to ice formation because the incoming air collides with it first. In contrast, ice formation on other parts of the blade is more likely to be due to the impact of ice formation on the blade's overall aerodynamic shape, causing the ice layer to gradually spread and grow.

[0035] Quantify the temporal and spatial development characteristics of ice on the blade surface. Critical values ​​are set for blade ice accumulation to become severe (or uncontrolled) at different spanwise locations. For example, within a specific time after ice onset, the percentage of ice coverage in the blade chord-wise direction reaches a certain critical value, or the ice thickness at a specific location on the blade exceeds a certain critical value within a specific time. Beyond this critical value, the blade will quickly become completely covered by growing ice due to the failure of the blade's aerodynamic properties.

[0036] Under these conditions, the temporal and spatial characteristics of blade icing were analyzed to determine the evolution of icing on the entire blade under different icing climates (including the ice area and thickness development). This database, which allows for the query of the time when ice appeared at a specific blade location and the evolution of ice thickness over time, was constructed. Generally, within a specific period of time after icing, ice may form on blade areas that are less susceptible to icing (such as the trailing edge). This is partly due to ice forming on the leading edge, which changes the blade's aerodynamic shape and affects the icing resistance of the corresponding area. Alternatively, it may be due to the growth and spread of ice.

[0037] From the aforementioned icing characteristics database, blade icing conditions under various typical weather conditions, including extreme icing, are selected to comprehensively determine the boundaries between the air-heat deicing zone and the air-heat / electric-heat hybrid deicing zone. Prioritizing, in extreme icing conditions, the area near the trailing edge of the blade where ice reaches a certain thickness within a certain period of time after the onset of ice (e.g., ice exceeding 2mm in 30 minutes) is selected as the deicing prevention range for the air-heat deicing technology. This area, in other words, is where deicing can be achieved solely with the air-heat deicing system. The selected areas can be appropriately adjusted based on the icing characteristics of typical icing conditions.

[0038] When the air-heat deicing system is in operation, based on the industry-standard hot air deicing technology, hot air is transported from the air duct into the blade cavity and begins to heat the entire blade. Due to the difference in blade thickness in the span direction and the chord direction, and the temperature drop of the transported hot air during the flow process, under the designed transport air parameters (temperature, flow rate, air pressure at the air duct outlet, etc.), the heating effect of the above-selected blade areas will be different, which is directly reflected in the difference in blade surface temperature.

[0039] Numerical simulation methods are used to observe the differences in the effects of hot air blowing on blade heating. That is, the target blade is modeled, and based on the above-mentioned conveying wind parameters, the boundary conditions between the atmospheric environment and the blade are set considering extreme icing weather, and the flow in the blade's internal flow channel and the heat transfer process are observed.

[0040] After the simulation converges, the temperature distribution of the blade outer surface in the above-defined area is observed. Combined with the blade icing characteristics database, it is required that the blade outer surface temperature in the selected area where icing occurs should not be lower than 0.5-1.5°C (in fact, when the outer surface temperature exceeds 0°C, it is difficult for supercooled water droplets in the air to collide with the blade surface to form ice, which is also conducive to the melting of ice that has spread to the area, achieving the expected anti-icing effect).

[0041] The airflow parameters of the air-heat deicing system were optimized and adjusted to ensure that the air temperature did not exceed the maximum allowable internal blade temperature (generally 70-75°C, with 70°C being chosen). This was done to meet the blade surface temperature requirements within the designated area as an iterative constraint. The energy consumption of the thermal deicing system was comprehensively compared to determine the optimal parameter combination. Areas with ice accumulation and poor heating performance due to factors such as blade thickness were removed from the designated area.

[0042] At the same time, based on numerical simulation results, the outer surface temperature distribution of the remaining blade areas (i.e., locations where ice formation occurs early and is most severe, such as the leading edge and blade tip) was observed under the designed input hot air parameters. Because the blade tip and other locations are thinner, the aerothermal deicing system alone can successfully prevent deicing, even if ice formation is severe there. Areas with blade outer surface temperatures exceeding 1.5°C were selected and added to the above-delineated area.

[0043] Blade areas outside of these designated zones are where ice formation and growth are most severe, and where the hot air blast heating is ineffective. In these areas, additional electric heating films are installed to create a regional electric heating anti-icing system, providing a hybrid air-heating and electric-heating anti-icing approach for the entire blade. A customized design is developed based on a database of blade surface temperature distribution, internal heat conductivity, and icing characteristics, taking into account the varying ice intensity in various regions under severe icing conditions. This involves selecting the rated power of the electric heating films at each location within the zone, creating a comprehensive design solution.

[0044] Finally, during the anti-icing modification construction phase of the target wind turbine blades, gas-thermal deicing modification is first performed on the inside of the blades, and then an electric heating film is laid on selected areas of the outer surface.

[0045] The above design primarily targets the specific icing climate of the target unit, customizing the design of the gas-heat deicing zones and electric deicing systems to ensure the unit's anti-icing requirements in extreme icing conditions. Under normal icing conditions, the gas-heat and electric deicing systems (or the gas-heat deicing system alone) can operate at lower power to meet blade anti-icing requirements. Specifically, based on a blade icing characteristics database developed through experimental analysis and combined with an ice monitoring system, the operating parameters of the gas-heat deicing system are adjusted to meet blade anti-icing requirements in mild freezing weather. If icing is detected in the area where the electric deicing system is deployed, the operating power of the electric heating film in each zone is similarly adjusted based on the blade icing characteristics database to collaboratively remove ice. This hybrid gas-heat and electric deicing system, combined with the ice characteristics database and surface ice monitoring system, not only achieves efficient anti-icing requirements for the target wind turbine under all historical climatic conditions but also reduces system energy consumption through optimized operating modes.

[0046] This invention proposes a design and operation method for a hybrid, high-efficiency anti-icing system for wind turbine blades that combines hot air blast and electric heating technologies. Based on wind tunnel icing tests, the temporal and spatial development characteristics of ice accumulation on the target wind turbine blades are determined, taking into account the actual conditions of the blade environment, weather conditions, and blade parameters. A database of the areas and thicknesses of ice accumulation during different time periods is then established. Based on the blade icing characteristics under different freezing levels, areas on the suction and pressure surfaces of the blades that are less susceptible to ice formation are comprehensively screened for air-heat deicing alone. Electric heating is used as a supplement for the remaining blade areas. Furthermore, the rated power of the electric heating film is tailored to the varying blade ice accumulation levels. After the system is operational, the blade icing characteristics database and ice monitoring are combined to determine whether to operate solely with the air-heat deicing system or a hybrid deicing system combining air-heat and electric heating under different freezing conditions. This ensures efficient anti-icing of wind turbine blades under all weather conditions (including extreme freezing conditions) while maintaining low energy consumption.

[0047] It should be noted that the above is only part of the embodiments of the present invention. Equivalent changes made to the system described in the present invention are all included in the scope of protection of the present invention. Those skilled in the art of the present invention may make similar substitutions for the specific examples described, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, and all such substitutions are within the scope of protection of the present invention.

Claims

1. A design method for a hybrid deicing system based on the icing characteristics of wind turbine blades, characterized in that: The following steps are involved: S1: Collect and analyze environmental and meteorological factors of wind turbines to determine the meteorological parameter combination for blade icing characteristic test; S2: Based on the actual blade conditions of the wind turbine, restore and make a blade icing test model; S3: In a wind tunnel test facility, based on the meteorological parameter combination determined in S1 and the blade icing test model prepared in S2, combined with the normal operating parameters of the wind turbine, restore the icing environment characteristics of the wind turbine blades; Observe the icing characteristics of the blade icing test model and obtain the temporal and spatial characteristics of icing on the blade surface; S4: Quantitatively analyze the spatiotemporal characteristics of blade surface icing obtained in S3 to obtain the evolution of blade icing in different time periods after icing begins to form, and obtain an icing characteristics database; S5: Based on the icing characteristics database obtained in S4, the blade icing conditions under various typical weather conditions, including extreme icing climates, are selected to comprehensively determine the boundaries of the air-heat deicing area alone and the air-heat / electric-heat hybrid deicing area; S6: Design the aerothermal deicing system and optimize its operating parameters based on numerical simulation methods. Then, based on the temperature distribution on the blade outer surface, update and supplement the aerothermal deicing area. S7: Install electric heating membranes in the air-heat / electric hybrid deicing area outside the air-heat deicing area, and customize the rated power of the electric heating membranes at each location to complete the design of the blade hybrid deicing system. S4 is specifically as follows: Based on the spatiotemporal characteristics of ice formation on the blade surface obtained in S3, the temporal and spatial development characteristics of ice appearance and growth on the blade under different freezing climate levels are analyzed, the patterns of ice appearance area and thickness development at different spanwise positions of the blade are obtained, and the critical thickness at which the ice condition deteriorates within a specific time is determined, thereby forming a database of ice characteristics of specific blades under different freezing climates; S5 specifically includes: based on the icing characteristics database obtained in S4 and in combination with the icing conditions of the blades under various typical icing climates, comprehensively determining the boundaries of the gas-heat deicing area alone and the gas-heat / electric-heat hybrid deicing area; In extreme icing climates, locations where a specific ice thickness forms within a preset time after ice begins to form and areas near the blade trailing edge are selected as separate gas-heat deicing areas. The rest of the blade area is the gas-heat / electric-heat hybrid deicing area.

2. The design method of a hybrid deicing system based on wind turbine blade icing characteristics according to claim 1, characterized in that: In S1, the environmental and meteorological factors include wind speed, air pressure, temperature, humidity and particle size distribution of supercooled water droplets in the air.

3. The design method of a hybrid deicing system based on wind turbine blade icing characteristics according to claim 1, characterized in that: In S1, the meteorological parameter combination includes main meteorological characteristics that can reflect normal icing weather and extreme freezing weather in which the wind turbine is located.

4. The design method of a hybrid deicing system based on wind turbine blade icing characteristics according to claim 1, characterized in that: In S2, the blade conditions include surface material, airfoil, length and surface roughness.

5. The design method of a hybrid deicing system based on wind turbine blade icing characteristics according to claim 1, characterized in that: In S3, the icing characteristics include the type, occurrence area and formation speed of blade icing.

6. The design method of a hybrid deicing system based on wind turbine blade icing characteristics according to claim 1, characterized in that: S6 specifically includes: combining conventional hot air deicing technology, observing the differences in the effects of hot air on blade heating based on numerical simulation methods, adjusting and iteratively optimizing the hot air delivery parameters, so that the blade surface temperature corresponding to the gas-heated deicing area is not lower than 0.5~1.5℃, and the maximum heating air temperature does not exceed 70℃; combining the blade outer surface temperature distribution under the optimized hot air delivery parameters, the gas-heated deicing area is updated and supplemented.

7. The design method of a hybrid deicing system based on wind turbine blade icing characteristics according to claim 1, characterized in that: S7 specifically includes: installing an electric heating film in the gas-heating / electric-heating mixed deicing area outside the gas-heating deicing area, and determining the rated power of the electric heating film in a differentiated manner based on the temperature distribution on the outer surface of the blade, the thermal conductivity rate inside the blade, and the icing characteristics database.

8. The design method of a hybrid deicing system based on wind turbine blade icing characteristics according to claim 1, characterized in that: Under normal icing climate conditions, based on the icing characteristics database and combined with the icing monitoring system, the operating parameters of the gas-heat deicing system are adjusted to meet the blade anti-icing needs in lighter freezing weather; in more severe or extreme freezing weather, combined with the icing monitoring and icing characteristics database of the electric heating film covering area, the operating power of the electric heating film in each area on the blade is optimized, and the gas-heat deicing system and the electric heat storage system are used to collaboratively remove ice from the blade.

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