A method, device and storage medium for determining the optimal deicing airflow temperature of a wind turbine

Abstract

The present invention discloses a method, device and storage medium for determining the optimal deicing airflow temperature of a wind turbine, and belongs to the technical field of wind power generation. First, the fan blade is equally divided into several intervals along the span direction from the deicing airflow outlet to the blade tip, and it is assumed that the internal structure of each interval is uniform, and a two-dimensional steady-state heat transfer analysis model of the fan blade is established, and a two-dimensional steady-state heat transfer numerical analysis is performed on the cross-sections between adjacent intervals; the deicing airflow critical temperature of each cross-section is obtained; then, each interval is used as a calculation unit, and the cross-section closest to the blade tip is used as the calculation starting point, and the deicing airflow critical temperature of each interval is reversely calculated interval by interval; finally, the deicing airflow critical temperature of the deicing airflow outlet is obtained. The present invention can reduce energy consumption, ensure deicing effect, and improve the overall gas-heat deicing efficiency of the fan while simplifying the calculation of the blade deicing model.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and in particular relates to a method, a device and a storage medium for determining an optimal deicing airflow temperature for a wind turbine. Background Art

[0002] For fans operating in high-humidity areas, when the ambient temperature drops to around 0°C, water droplets in the humid air hit the surface of the blade shell (the surface temperature of the blade shell is not greater than the ambient temperature), latent heat is released and ice occurs.

[0003] At present, in order to prevent the impact of ice, the market uses gas heating method, electric heating method and other methods to remove ice. Among them, gas heating method is widely used because of its high safety. However, the energy consumption of gas heating method is high, which will lead to high energy consumption and reduce system efficiency. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method, device and storage medium for determining the optimal deicing airflow temperature of a wind turbine, which can simplify the calculation of the blade deicing model, reduce energy consumption, ensure the deicing effect, and improve the overall air-heat deicing efficiency of the wind turbine.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention discloses a method for determining an optimal deicing airflow temperature of a wind turbine, comprising:

[0007] S1: The fan blade is divided into several equal sections along the span direction from the deicing airflow outlet to the blade tip, and the internal structure of each section is assumed to be uniform. A two-dimensional steady-state heat transfer analysis model of the fan blade is established, and a two-dimensional steady-state heat transfer numerical analysis is performed on the cross-sections between adjacent sections;

[0008] S2: Based on the analysis results of S1 and the steady-state heat balance equation of the outer surface of the fan blade, calculate the critical heat flux density of the deicing airflow in each cross section that makes the outer surface of the fan blade at the critical deicing temperature;

[0009] S3: Calculate the inner surface temperature of each section of the fan blade that makes the outer surface of the fan blade at the critical deicing temperature according to the outer surface temperature of the fan blade and the heat transfer characteristics of each blade layer;

[0010] S4: Calculate the critical temperature of the deicing airflow at each section according to the inner surface temperature of the blade at each section and the heat exchange relationship between the deicing airflow and the inner surface of the fan blade;

[0011] S5: Taking each interval as a calculation unit and the cross section closest to the blade tip as the calculation starting point, the critical temperature of the deicing airflow in each interval is reversely calculated interval by interval; finally, the critical temperature of the deicing airflow at the deicing airflow outlet is obtained.

[0012] Preferably, in S2, the steady-state heat balance equation of the outer surface of the fan blade is:

[0013]

[0014] Where c is the specific heat capacity of the fan blade, m is the mass per unit area of ​​the fan blade surface skin, and q j The total heat flux provided by the heating element, q h It is the total heat flux density of the fan blade surface.

[0015] More preferably, q h is the blade surface temperature T, the ambient temperature T a , a function of the incoming flow relative velocity u and air humidity w.

[0016] Further preferably, in S3, the blade inner surface temperature of each section is calculated using the following formula:

[0017]

[0018] Among them, δ i is the thickness of each ply at the corresponding cross section, λ i is the thermal conductivity of each ply at the corresponding cross section.

[0019] Further preferably, in S4, the critical temperature of the deicing airflow in each section is:

[0020]

[0021] Where h is the convective heat transfer coefficient between the deicing airflow and the inner wall of the blade.

[0022] Further preferably, h is a function of gas flow rate, temperature and viscosity.

[0023] Further preferably, in S5, the critical temperature of the deicing airflow in each interval is calculated using the following formula:

[0024]

[0025] Among them, A i is the inner surface area of ​​the blade in this interval, c i is the specific heat of the blade in this interval, is the mass flow rate of the deicing airflow, t in,i is the critical temperature of the deicing airflow at the inlet section of this interval, t o,i is the critical temperature of the deicing airflow at the outlet section of this interval.

[0026] Further preferably, in S5, the outlet airflow temperature of the i-1th interval is taken as the theoretical minimum deicing airflow temperature T of the outlet section.g,min,i-1 and the inlet deicing airflow temperature t required to meet the deicing effect of the outlet section of the i-th interval in,i The larger value between the two, t o,i-1 =max[t in,i ,T g,min,i-1 ].

[0027] The present invention discloses a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for determining the optimal deicing airflow temperature of a wind turbine are implemented.

[0028] The present invention discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for determining the optimal deicing airflow temperature of a wind turbine are implemented.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] The method for determining the optimal deicing airflow temperature of a wind turbine disclosed in the present invention divides the fan blades into a number of equal intervals along the span direction from the deicing airflow outlet to the blade tip, establishes a two-dimensional steady-state heat transfer analysis model of the fan blades, and adopts the idea of ​​differentiation to simplify the calculation of the blade deicing model while maximally ensuring the reliability of the calculation results. The relationship between the optimal deicing airflow temperature of the wind turbine and the environmental parameters is considered in the calculation process, which is more in line with the actual situation; at the same time, each interval is used as a calculation unit, and the section closest to the blade tip is used as the calculation starting point, and the critical temperature of the deicing airflow of each interval is calculated inversely one by one. In the process of deduction, in order to meet the deicing airflow temperature required by the outlet section of a certain interval, if the required inlet airflow temperature of the interval calculated by the heat balance equation is less than the optimal deicing airflow temperature of the inlet section, then the optimal deicing airflow temperature of the section is taken as the outlet airflow temperature of the next calculation interval; and if the required inlet airflow temperature of the interval is greater than the optimal deicing airflow temperature of the inlet section, then the required inlet airflow temperature of the interval is taken as the basis for calculating the outlet airflow temperature of the next interval. After comparing the values, it can be ensured that each section meets the deicing conditions and that all parts of the entire fan blade can achieve the ideal deicing effect. The present invention can reduce energy consumption, ensure deicing effect, and improve the overall gas-heat deicing efficiency of the fan while simplifying the calculation of the blade deicing model, providing a theoretical basis for the operation and maintenance of the fan gas-heat deicing system, reducing energy consumption, and improving the economy of fan operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the division of blade intervals;

[0032] Figure 2 Schematic diagram of gas flow in a single blade interval. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0034] A method for determining an optimal deicing airflow temperature for a wind turbine according to the present invention comprises:

[0035] S1: The fan blade is divided into several equal sections along the span direction from the deicing airflow outlet to the blade tip, and the internal structure of each section is assumed to be uniform. A two-dimensional steady-state heat transfer analysis model of the fan blade is established, and a two-dimensional steady-state heat transfer numerical analysis is performed on the cross-sections between adjacent sections;

[0036] S2: Based on the analysis results of S1 and the steady-state heat balance equation of the outer surface of the fan blade, calculate the critical heat flux density of the deicing airflow of each section that makes the outer surface of the fan blade at the critical deicing temperature; the steady-state heat balance equation of the outer surface of the fan blade is:

[0037]

[0038] Where c is the specific heat capacity of the fan blade, m is the mass per unit area of ​​the fan blade surface skin, and q j The total heat flux provided by the heating element, q h is the total heat flux density of the fan blade surface; q h is the blade surface temperature T, the ambient temperature T a , a function of the incoming flow relative velocity u and air humidity w.

[0039] S3: Based on the outer surface temperature of the fan blade and the heat transfer characteristics of each blade layer, calculate the inner surface temperature of each section of the fan blade that makes the outer surface of the fan blade at the critical deicing temperature; the inner surface temperature of each section of the blade is calculated using the following formula:

[0040]

[0041] Among them, δi is the thickness of each ply at the corresponding cross section, and λi is the thermal conductivity of each ply at the corresponding cross section.

[0042] S4: Calculate the critical temperature of the deicing airflow at each section according to the inner surface temperature of the blade at each section and the heat exchange relationship between the deicing airflow and the inner surface of the fan blade; the critical temperature of the deicing airflow at each section is:

[0043]

[0044] Where h is the convective heat transfer coefficient between the deicing airflow and the inner wall of the blade; h is a function of the airflow velocity, temperature and viscosity.

[0045] S5: Taking each interval as a calculation unit and the cross section closest to the blade tip as the calculation starting point, the critical temperature of the deicing airflow in each interval is reversely calculated interval by interval; finally, the critical temperature of the deicing airflow at the deicing airflow outlet is obtained.

[0046] The critical temperature of the deicing airflow in each zone is calculated using the following formula:

[0047]

[0048] Among them, A i is the inner surface area of ​​the blade in this interval, c i is the specific heat of the blade in this interval, is the mass flow rate of the deicing airflow, t in,i is the critical temperature of the deicing airflow at the inlet section of this interval, t o,i is the critical temperature of the deicing airflow at the outlet section of this interval.

[0049] The outlet airflow temperature of the i-1th interval is the theoretical minimum deicing airflow temperature T of the outlet section. g,min,i-1 and the inlet deicing airflow temperature t required to meet the deicing effect of the outlet section of the i-th interval in,i The larger value between the two, t o,i-1 =max[t in,i ,T g,min,i-1 ].

[0050] The present invention is further explained below with a specific embodiment:

[0051] Taking 0.1 wind turbine radius R (i.e., wind turbine blade length) as a unit, the wind turbine blade is divided into different intervals, which are respectively recorded as interval ①, interval ②, ... interval ⑩. Within the same interval, it is approximately assumed that the heat transfer performance of different sections is consistent. Generally speaking, the heating pipe of gas-heat deicing can extend to 0.2R, so the deicing airflow outlet can be approximately considered to be at 0.2R. It should be noted that in this embodiment, the root of the fan blade is used as the starting point for dividing the interval, so as to analyze the structure of the entire blade at the same time, and the analytical calculation results of the deicing airflow outlet temperature are consistent with taking the deicing airflow outlet as the starting point for dividing the interval. The inlet and outlet sections of each interval are selected as the research sections, that is, the sections at 0.2R, 0.3R, ... 0.9R, and steady-state thermal balance calculations are performed separately according to the ply structure information and heat transfer characteristics of each section. Simplified modeling is performed on each two-dimensional section, and a steady-state heat balance equation is established to solve the deicing heat flux density and the corresponding deicing airflow temperature when the blade surface temperature reaches the critical deicing temperature under specific environmental conditions (temperature, humidity, wind speed, tip speed ratio, etc.). In order to confirm the deicing airflow temperature at the outlet of the gas-heat deicing heater when each section reaches the critical deicing point, a deduction algorithm is adopted, with the fan blade interval of 0.1R as the calculation unit and the outlet section of the farther section ⑨ as the calculation starting point, to reversely infer the deicing airflow temperature at the outlet of the heater. In the deduction process, in order to meet the deicing airflow temperature required for the outlet section of a certain interval, if the required inlet airflow temperature of the interval calculated by the heat balance equation is less than the optimal deicing airflow temperature of the inlet section, the optimal deicing airflow temperature of the section is taken as the outlet airflow temperature of the next calculation interval; and if the required inlet airflow temperature of the interval is greater than the optimal deicing airflow temperature of the inlet section, the required inlet airflow temperature of the interval is taken as the basis for calculating the outlet airflow temperature of the next interval. Finally, the outlet airflow temperature at 0.3R is combined with the heat transfer in the range of 0.2R to 0.3R of the blade to obtain the outlet temperature of the deicing airflow of the fan at 0.2R. This temperature is the optimal deicing airflow temperature that allows the blade to be fully deiced.

[0052] Figure 1 A schematic diagram of the interval division of the blade is given. Since the structure of the blade is relatively complex, it not only has bending but also a certain degree of torsion. Therefore, the structure of the blade is simplified. The blade is equally divided into 10 intervals, and the blade structure is considered to be uniform inside each interval. The inlet and outlet sections of each interval, that is, the 8 sections in the interval of 0.2R~0.9R, are taken as the research objects, and the two-dimensional steady-state heat transfer numerical analysis is performed on the 8 planes respectively. For the outer surface of the blade, a steady-state heat balance equation is established. The heat flux density provided by the heated gas inside the blade should be balanced with the radiation heat dissipation, convection heat dissipation, and evaporation heat dissipation of the water droplets on the outer surface of the blade, that is:

[0053]

[0054] Where c is the specific heat capacity of the blade, m is the mass per unit area of ​​the blade surface skin, q j The total heat flux provided by the heating element, q h is the total heat flux density of the blade surface, q h It can also be expressed as blade surface temperature T, ambient temperature T a , relative velocity u of incoming flow, air humidity w, etc. When the blade surface is in thermal equilibrium, dT / dt = 0, and the critical deicing temperature of the blade outer surface is set to T = 3°C. According to the thermal equilibrium equation, the critical heat flux density q that makes the blade outer surface at the critical deicing temperature can be obtained: j,c .

[0055] According to the outer surface temperature of the blade and the heat transfer characteristics of each blade layer, the inner surface temperature of the blade is obtained when the outer surface of the blade reaches the critical deicing temperature. Among them, δ i , i They correspond to the thickness and thermal conductivity of each layer at the cross section.

[0056] According to the inner surface temperature of the blade and the heat exchange between the deicing airflow and the inner surface of the blade, the critical deicing airflow temperature is inversely calculated. h is the convective heat transfer coefficient between the deicing airflow and the inner wall of the blade, which is determined by airflow velocity, temperature, viscosity and other parameters. The above steady-state heat balance calculation is performed on each section to obtain the minimum deicing airflow temperature T corresponding to each section. g,min,i .

[0057] Since the deicing airflow in the blade flows in a constant direction, near the leading edge of the blade, the airflow flows from the blade root to the blade tip. Therefore, the temperature of the airflow cannot be controlled locally, and the airflow temperature at a certain position is determined by the heat transfer characteristics upstream of that position. The airflow temperature at the heater outlet should be able to satisfy the requirement that the deicing airflow temperature at any cross section is greater than or equal to its minimum deicing airflow temperature. In order to confirm the deicing airflow temperature at the outlet of the gas-heated deicing heater when each cross section reaches the critical deicing point, a differential method is used and a deductive algorithm is adopted. The fan blade interval of 0.1R is used as the calculation unit, and the farther end 0.9R is used as the calculation starting point to reverse the deicing airflow temperature at the heater outlet. Taking the blade unit between 0.8R and 0.9R as an example, if Figure 2 It is approximately assumed that within this range, the geometric parameters and structural parameters of the 0.9R section are used as the benchmark, and the material and structure are evenly distributed. Taking the lowest deicing airflow temperature at the 0.9R section as the calculation starting point, the minimum deicing heat flux density required for this section is q j,c,9 , as the outlet of this interval, the corresponding critical deicing air flow temperature is t o,9 =T g,min,9The surface area of ​​the blade in this interval is A9, the specific heat of the blade in this interval is c9, and the mass flow rate of the deicing airflow is According to the law of conservation of energy, The inlet air temperature t in this interval to meet the deicing air temperature at the outlet can be inferred in,9 At this time, the following comparison is performed. If t in,9 ≥T g,min,8 , then t in,9 As the minimum deicing air flow temperature at the outlet of the 0.7R~0.8R interval, t o,8 =t in,9 Otherwise, T g,min,8 As the minimum deicing air flow temperature at the outlet of the 0.7R~0.8R interval,

[0058] t o,i-1 =max[t in,i ,T g,min,i-1 ].

[0059] By analogy, in intervals, we can infer the minimum deicing airflow temperature T required at the outlet of the heat pipe at 0.2R. o,2 , which is the minimum temperature of the deicing airflow under specific operating conditions.

[0060] By changing the ambient temperature, humidity, wind speed and other parameters and following the same calculation method, the minimum deicing airflow temperature required at the heater outlet under different environmental conditions can be obtained.

[0061] It is worth noting that the present invention uses the idea of ​​differentiation to divide the blade into 10 intervals along the span direction. Generally, the blade can be divided into N intervals along the span direction (N is an integer). The larger N is, the higher the corresponding calculation accuracy is.

[0062] The present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for determining the optimal deicing airflow temperature of a wind turbine described in the present invention are implemented.

[0063] The method for determining the optimal deicing airflow temperature of a wind turbine of the present invention may be implemented in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may be implemented in the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. If the method for determining the optimal deicing airflow temperature of a wind turbine of the present invention is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0064] Based on such understanding, in an exemplary embodiment, a computer-readable storage medium is also provided. The present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing related hardware through a computer program. The computer program can be stored in the computer-readable storage medium. When the computer program is executed by the processor, the steps of each of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable storage media include permanent and non-permanent, removable and non-removable media, and information storage can be achieved by any method or technology. Information can be computer-readable instructions, data structures, program modules or other data. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals. Among them, the computer storage medium can be any available medium or data storage device that can be accessed by the computer, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NANDFLASH), solid-state drive (SSD)), etc.

[0065] In an exemplary embodiment, a computer device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for determining the optimal deicing airflow temperature of a wind turbine when executing the computer program. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc.

[0066] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

[0067] The above description is only a specific implementation of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for determining the optimal deicing airflow temperature of a wind turbine, characterized in that: include: S1: The fan blade is divided into several equal sections along the span direction from the deicing airflow outlet to the blade tip, and the internal structure of each section is assumed to be uniform. A two-dimensional steady-state heat transfer analysis model of the fan blade is established, and a two-dimensional steady-state heat transfer numerical analysis is performed on the cross-sections between adjacent sections; S2: Based on the analysis results of S1 and the steady-state heat balance equation of the outer surface of the fan blade, calculate the critical heat flux density of the deicing airflow in each cross section that makes the outer surface of the fan blade at the critical deicing temperature; S3: Calculate the inner surface temperature of each section of the fan blade that makes the outer surface of the fan blade at the critical deicing temperature according to the outer surface temperature of the fan blade and the heat transfer characteristics of each blade layer; The blade inner surface temperature of each section is calculated using the following formula: T i = q j,c in, is the thickness of each ply at the corresponding cross section, is the thermal conductivity of each ply at the corresponding cross section, T is the blade surface temperature; S4: Calculate the critical temperature of the deicing airflow at each section according to the inner surface temperature of the blade at each section and the heat exchange relationship between the deicing airflow and the inner surface of the fan blade; The critical temperature of deicing airflow at each section is: T g,min= + T i in, h is the convective heat transfer coefficient between the deicing airflow and the inner wall of the blade; h It is a function of air flow rate, temperature and viscosity; S5: Taking each interval as a calculation unit and the cross section closest to the blade tip as the calculation starting point, the critical temperature of the deicing airflow of each interval is calculated inversely one by one; finally, the critical temperature of the deicing airflow at the outlet of the deicing airflow is obtained; The critical temperature of the deicing airflow in each zone is calculated using the following formula: c i （ t in,i - t o,i ）= q j,c,i A i in, A i is the inner surface area of ​​the blade in this interval, c i is the specific heat of the blade in this interval, is the mass flow rate of the deicing airflow, t in,i is the critical temperature of the deicing airflow at the inlet section of this interval, t o,i is the critical temperature of the deicing airflow at the outlet section of this interval; No. i The outlet airflow temperature of the -1 interval is the theoretical minimum deicing airflow temperature of the outlet section. T g,min,i-1 and to satisfy the i The inlet deicing airflow temperature required for the deicing effect of the outlet cross-section of the interval t in,i The larger value between the two, t o,i-1 = max [ t in,i , T g,min,i-1 ].

2. The method for determining the optimal deicing airflow temperature of a wind turbine according to claim 1, characterized in that: In S2, the steady-state heat balance equation of the outer surface of the fan blade is: in, c is the specific heat capacity of the fan blade, m is the mass per unit area of ​​the fan blade surface skin, q j The sum of the heat flux provided to the heating element, q h It is the total heat flux density of the fan blade surface.

3. The method for determining the optimal deicing airflow temperature of a wind turbine according to claim 2, characterized in that: q h is the blade surface temperature T , Ambient temperature T a , relative velocity of incoming flow u and air humidity w function.

4. A computer device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method for determining the optimal deicing airflow temperature of a wind turbine as claimed in any one of claims 1 to 3 are implemented.

5. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for determining the optimal deicing airflow temperature for a wind turbine according to any one of claims 1 to 3 are implemented.

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