A self-feedback anti-icing and de-icing method for fan blades based on DTS system

Abstract

The present invention discloses a self-feedback anti-icing and deicing method for fan blades based on a DTS system, comprising: installing a polymer heating film; laying a temperature measuring optical cable; temperature calibration; low-power heating test; ice point determination; high-power heating and deicing. The present invention uses DTS technology to monitor the ice coverage of fan blades. The temperature change causes the change of the optical signal in the optical fiber. By performing signal demodulation, the temperature distribution at different positions of the optical fiber is obtained; then, the heating resistor at the corresponding position is started according to the temperature distribution of the optical fiber, and the ice-covered area is heated and deiced in real time, thereby realizing a self-feedback electric heating deicing method.

Description

Technical Field

[0001] The invention belongs to the technical field of distributed optical fiber sensing, and in particular relates to a self-feedback anti-icing and deicing method for fan blades based on a DTS system. Background Art

[0002] The excessive consumption of traditional energy has led to increasingly severe energy security and ecological environmental problems. The world is actively exploring the development of clean and renewable energy. Wind energy, as an inexhaustible new energy source, is abundant in the south and developed coastal cities. Vigorously promoting the development of the wind power industry will promote my country's energy structure adjustment and the construction of the entire ecological civilization.

[0003] In order to better obtain wind energy, wind farms are often built in high-altitude mountains and hilly areas. The winter climate in the southern region is low temperature and high humidity, and wind resources are mainly distributed in high-altitude mountainous areas and lakes. With the decrease in temperature, low temperature and freezing weather are often encountered. This high humidity and low temperature weather often causes ice to cover the blades of wind turbines. The ice on the blades of wind turbines has a significant impact on the safe and stable production of wind turbines. It is of great significance to study the anti-icing technology of wind turbines.

[0004] Ice on blades is mainly concentrated in the leading edge and trailing edge, which will significantly affect the shape and roughness of the blades and change the aerodynamic characteristics of the original blades. Ice accumulation and irregular shedding will cause the unit output power to drop, aggravate vibration and damage transmission parts and connectors; seriously affect the life of the wind wheel, transmission chain and the whole machine; under severe working conditions, cause blade breakage. After the blades are covered with ice, as the temperature rises, the ice will fall off, posing a great safety hazard.

[0005] Currently, wind turbine blade icing monitoring is mainly based on manual observation and ground infrared detection, which detects the mass and ice layer directly through reflective lamps, or monitors the power generation through sensors, and determines blade faults based on the experience of staff. The observation efficiency is low, the recognition rate is poor, and the working status of the wind turbine cannot be evaluated objectively and in real time.

[0006] Common deicing methods for wind turbine blades include active deicing and passive deicing. Active deicing includes thermal deicing, electric deicing and mechanical deicing. Passive deicing mainly includes methods such as hydrophobic coatings, photothermal coatings and spraying chemicals. In active deicing, thermal deicing uses various thermal energies to heat the blades to achieve the purpose of deicing and deicing. It has a wide range of applicability, but consumes a lot of electricity and has a high cost of transformation. Electric thermal deicing is to build a heating film into the blade when it is made, which can better achieve deicing and deicing, but this solution is not suitable for the transformation and upgrading of existing blades in wind farms, and there is a greater risk of lightning strikes, and it is difficult to repair after damage. Passive deicing mainly includes methods such as coating deicing and spraying chemicals. The principle of coating deicing is the lotus effect, which makes it difficult for water to infiltrate and adhere to the surface, and the surface is not easy to freeze. However, the existing coating deicing technology cannot completely solve the problem of blade icing, and the coating itself has a short life, and the long-term deicing effect is not ideal.

[0007] In active deicing, electric heating elements are more efficient and are currently the preferred deicing solution by various manufacturers. Traditional electric heating deicing technology generally uses metal resistance wires or metal meshes, which are prone to interface problems with the blades and pose the risk of local overheating.

[0008] The invention with the publication number CN110118157A discloses a method, device, blade and wind turbine for deicing a wind turbine blade, including: detecting the degree of ice at at least two positions of the leading edge of the blade, judging the ice level of the leading edge of the blade according to the degree of ice, and selecting one of the first heating level, the second heating level or the third heating level for heating according to the ice level of the leading edge of the blade; wherein the at least two positions include the leading edge of the blade tip and the leading edge of the blade root; the heating area of ​​the first heating level is the heating area at the front end of the leading edge of the blade, and the heating area of ​​the second heating level is the heating area on both sides of the leading edge of the blade; the heating power density of the heating area at the front end of the leading edge of the blade is greater than the heating power density of the heating areas on both sides of the leading edge of the blade; the invention can detect the degree of ice at different areas of the leading edge of the blade in real time and accurately, reduce the heating power while being able to quickly and effectively melt ice, and can reduce the cost of deicing and increase the power generation. However, the invention needs to use an ice sensor to judge the degree of ice, and although the heating is carried out in different areas, it does not involve the technical problem of local overheating.

[0009] The invention with publication number CN105089929A ​​discloses a wind turbine blade icing detection system, including: a data monitoring unit, a control unit, a temperature sensor, a speed sensor and anemometer. The data monitoring unit detects the ambient temperature outside the cabin through the temperature sensor, the data monitoring unit detects the real-time wind speed through the anemometer, the data monitoring unit detects the real-time wind rotor speed through the speed sensor, inputs the real-time wind speed and the real-time wind rotor speed into the control unit, and forms a real-time power curve point through the real-time output power of the fan provided by the control unit. The control unit determines whether the fan blades are frozen by comparing the real-time power curve point with the operating power curve when the fan is not frozen. This invention aims at the defects of low stability and reliability of the current icing detection technology, and can use different methods for detection when the fan is in the shutdown and running states, respectively, with accurate detection, high reliability and low cost. However, the operating power curve is affected by many external factors, so the ice detection accuracy is low, and it does not involve technical issues such as how to achieve regional heating or local overheating.

[0010] The invention with publication number CN110425094A discloses a freezing detection device and method for wind turbine blades based on optical principles. By using the difference in light flux received by the optical fiber bundles at different positions in the optical fiber detection head when freezing occurs, the occurrence of freezing, the freezing type and the degree of freezing can be accurately judged, and the detection accuracy is high. By setting a wedge-shaped optical fiber detection head at different positions of the blade, the freezing position can also be effectively located, which plays a guiding role in the subsequent de-icing work of the heating device. This invention solves the problem that it is currently difficult to detect freezing-related conditions of wind turbine blades, responds quickly, plays an important role in the safe and stable operation of wind turbines, and has extremely high practical value. Similarly, this invention only involves the judgment process of whether freezing has occurred and the degree of freezing, and does not involve technical issues such as how to achieve regional heating or local overheating. Summary of the invention

[0011] Technical problem to be solved: The present invention proposes a self-feedback anti-icing and de-icing method for fan blades based on a DTS system, which uses distributed fiber temperature sensing (DTS) technology to monitor the icing condition of the fan blades and realize self-feedback icing and de-icing.

[0012] Technical solution:

[0013] A self-feedback anti-icing and de-icing method for fan blades based on a DTS system, the self-feedback anti-icing and de-icing method for fan blades comprising the following steps:

[0014] S1, installing polymer heating films: using adhesive to distribute and fix multiple sheet-shaped polymer heating films on the fan blades, with gaps between adjacent polymer heating films; in order to achieve a high coverage rate on the fan blade surface, the gap is minimized on the basis of retaining the connection circuit construction distance; the polymer heating films are connected in parallel to the power control module, and the power control module is used to independently control the working state of each polymer heating film;

[0015] S2, laying out the temperature measuring optical cable: on the surface of the polymer heating film away from the fan blade, lay out the loose-sleeved temperature measuring optical cable in an S-shaped coil along the length direction of the blade, so that the optical fiber detection range completely covers the gap between the polymer heating film and the polymer heating film;

[0016] S3, temperature calibration: connect the temperature measuring optical cable to the DTS host for temperature calibration, measure the change of the optical signal in the temperature measuring optical cable over time in the preset ambient temperature range without ice, perform temperature demodulation along the temperature measuring optical cable, and calculate the optical fiber temperature coefficient;

[0017] S4, low-power heating test: connect the DTS host, power control module and polymer heating film in sequence. When the ambient temperature is below 0°C, call the power control module to perform a low-power heating test, monitor the fan blade heating rate when there is no ice, and record the fan blade heating rate data when there is no ice.

[0018] S5, ice point determination: In low temperature, high humidity and ice-prone seasons, start the DTS host, use the temperature measuring optical cable to continuously monitor the temperature, and feed back the temperature monitoring results to the DTS host; when the temperature is detected to be lower than 0°C, call the power control module to use the preset test power to perform low-power active heating on the entire fan blade. The heating power is determined by the resistance of the polymer heating film and the area of ​​the single heating film. Detect the heating rate at different positions and compare it with the heating rate data of the un-iced fan blade recorded in step S4. According to the characteristic that the air heating rate is much higher than the ice under the same heating conditions, for the position point where the actual heating rate is lower than the un-iced heating rate and the rate difference is greater than the preset difference threshold, determine that ice is present at that position point;

[0019] S6, high-power heating and deicing: For locations with ice, call the power control module, combine the comparison results of the actual heating rate and the heating rate without ice, the size of the fan blades and the coverage area of ​​the polymer heating film, calculate the corresponding heating power, and call the polymer heating film for deicing. When the monitored ice point exists on the coverage area of ​​the heating film, start the heating film at the corresponding position for deicing; when the ice point appears in the gap without heating film coverage, select the adjacent heating film closest to the position and heat it for deicing; continue to monitor temperature changes, and when the temperature at the ice point is higher than the freezing point for a duration greater than the preset time threshold, stop heating and return to step S5.

[0020] Furthermore, in step S2, the surface of the temperature measuring optical cable is covered with an epoxy resin protected optical fiber, and the outermost layer of the epoxy resin protected optical fiber is coated with a polyurethane insulating coating.

[0021] Furthermore, the wind turbine blade self-feedback anti-icing and de-icing method further comprises:

[0022] The DTS host, temperature measuring optical cable, power control module and polymer heating film are powered by the hub power supply module inside the fan blade.

[0023] Furthermore, the wind turbine blade self-feedback anti-icing and de-icing method further comprises:

[0024] The heating power is controlled by controlling the conduction time of the AC power supply through thyristors and IGBTs.

[0025] Furthermore, the wind turbine blade self-feedback anti-icing and de-icing method further comprises:

[0026] The AC power output by the hub power supply module inside the fan blade is converted into DC power, and the power is controlled by controlling the applied voltage of the polymer heating film.

[0027] Furthermore, the DTS host selects one of the Brillouin optical time domain reflection technology, Raman optical time domain reflection technology and Brillouin optical time domain analysis technology according to the actual wiring situation and the use environment to measure the temperature distribution of the fan blades.

[0028] Furthermore, the preset ambient temperature range is -20°C to 10°C.

[0029] Furthermore, the wind turbine blade self-feedback anti-icing and de-icing method further comprises:

[0030] The temperature measuring optical cable and polymer heating film are pre-buried in the fan blades.

[0031] Based on the above method, the present invention also mentions a self-feedback anti-icing and deicing system for fan blades based on the DTS system, wherein the self-feedback anti-icing and deicing system for fan blades comprises a DTS host, a loose sleeve temperature measurement optical cable, a power control module and a polymer heating film;

[0032] The polymer heating films are distributed and fixed on the fan blades by adhesive, and there are gaps between adjacent polymer heating films; all polymer heating films are connected in parallel to a power control module, and the power control module independently controls the working state of each polymer heating film;

[0033] The loose tube temperature measurement optical cable is coiled in an S shape along the length direction of the blade on the surface of the polymer heating film away from the fan blade, so that the optical fiber detection range completely covers the gap between the polymer heating film and the polymer heating film;

[0034] The DTS host is connected to the temperature measuring optical cable, and the DTS host is embedded with a temperature calibration module, a low-power heating test module, an ice point judgment module and a high-power deicing module;

[0035] The temperature calibration module is used to measure the change of the optical signal in the temperature measuring optical cable over time without ice in the preset ambient temperature range, perform temperature demodulation along the temperature measuring optical cable, and calculate the optical fiber temperature coefficient; the preset ambient temperature range is -20°C to 10°C;

[0036] The low-power heating test module is used to call the power control module to perform a low-power heating test when the ambient temperature is below 0°C. The heating power is determined by the resistance of the polymer heating film and the area of ​​the single heating film. The heating voltage is selected according to the formula

[0037]

[0038] Calculate, where P is power density, U is voltage, R is resistance, and S is the area of ​​a single polymer electric heating film. Monitor the temperature rise rate of the fan blades when there is no ice, and record the temperature rise rate data of the fan blades when there is no ice;

[0039] The ice point judgment module is used to start the DTS host in the low temperature, high humidity and ice-prone season, and call the temperature measurement optical cable to continuously monitor the temperature; when the temperature is detected to be lower than 0°C, the power control module is called to use the preset test power to actively heat the entire fan blade at low power, detect the heating rate at different positions, and compare it with the locally recorded heating rate data of the fan blade without ice. The maximum temperature rise DT calculation formula within 1 minute is:

[0040]

[0041] Among them, Q is the calorific value of the polymer heating film, SH is the specific heat of the heated material, De is the specific gravity of the heated material, and V is the volume.

[0042] The specific heat and specific gravity of air and ice can be obtained. When the same volume and power are heated, the temperature rise of air within 1 minute is 1478 times that of ice. Therefore, according to the characteristic that the air heating rate is much higher than that of ice under the same heating conditions, for the position point where the actual heating rate is lower than the heating rate without ice and the rate difference is greater than the preset difference threshold, it is determined that ice is present at this position point;

[0043] The high-power heating and deicing module is used to call the power control module, and calculate the corresponding heating power based on the comparison results of the actual heating rate and the heating rate without ice coating, the size of the fan blades and the coverage area of ​​the polymer heating film. When the monitored ice coating point exists on the coverage area of ​​the heating film, the heating film at the corresponding position is started to de-ice; when the ice coating point appears in the gap not covered by the heating film, the adjacent heating film closest to the position is selected, heated for de-icing, and the temperature changes are continuously monitored. When the temperature at the ice coating is higher than the freezing point for a duration greater than the preset time threshold, the heating is stopped.

[0044] The self-feedback anti-icing and deicing method for fan blades based on the DTS system of the present invention can monitor the ice coverage of the fan blades by using the DTS technology. The temperature change causes the change of the optical signal in the optical fiber. By demodulating the signal, the temperature distribution at different positions of the optical fiber can be obtained. The heating resistor at the corresponding position is started according to the temperature distribution of the optical fiber, and the ice-covered area is heated and de-iced in real time, thereby realizing a self-feedback electric heating de-icing method.

[0045] Beneficial effects:

[0046] First, the self-feedback anti-icing and de-icing method for fan blades based on the DTS system of the present invention realizes dynamic real-time monitoring of the surface temperature of the fan blades through the DTS system, has the characteristics of high sensitivity and large coverage area, and greatly reduces the missed reporting rate of icing events.

[0047] Second, in the self-feedback anti-icing and de-icing method for fan blades based on the DTS system of the present invention, the temperature measurement principle of the DTS system can be flexibly selected according to actual needs, and the system can be removed in the non-icing season, which can improve the system utilization rate, reduce the probability of mechanical failure, and effectively increase the service life of the system.

[0048] Third, the self-feedback anti-icing and deicing method for fan blades based on the DTS system of the present invention uses multiple sets of heating films and independently controls the opening and closing, which can achieve point-to-point precise deicing and has the advantages of energy saving, emission reduction and high efficiency.

[0049] Fourthly, the self-feedback anti-icing and deicing method for fan blades based on the DTS system of the present invention can automatically determine the icing situation and perform deicing operations, thereby realizing automatic control and greatly reducing labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a flowchart of a self-feedback anti-icing and de-icing method for wind turbine blades based on a DTS system according to an embodiment of the present invention.

[0051] Figure 2 This is a diagram of the layout of the loose tube temperature measurement optical cable and polymer heating film on the surface of the wind turbine blade.

[0052] Figure 3 FIG. 4 is a circuit diagram of a power control module according to an embodiment of the present invention.

[0053] Figure 4 Schematic diagram of the local position of the loose tube temperature measurement optical cable and the heating film.

[0054] Figure 5 Schematic diagram of the relationship between modules in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following examples will enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0056] Figure 1 This is a flow chart of a self-feedback anti-icing and de-icing method for wind turbine blades based on a DTS system according to an embodiment of the present invention. Figure 1 The self-feedback anti-icing and de-icing method for fan blades includes the following steps:

[0057] S1, installing polymer heating films: using adhesive to distribute and fix multiple sheet-shaped polymer heating films on the fan blades, with gaps between adjacent polymer heating films; the gaps should be selected on the basis of not affecting the normal connection of the circuit and achieving maximum coverage of the fan blade surface; the polymer heating films are connected in parallel to the power control module, and the power control module is used to independently control the working state of each polymer heating film;

[0058] S2, laying out the temperature measuring optical cable: on the surface of the polymer heating film away from the fan blade, lay out the loose-sleeved temperature measuring optical cable in an S-shaped coil along the length of the blade, so that the optical fiber detection range completely covers the gap between the polymer heating film and the polymer heating film.

[0059] S3, temperature calibration: connect the temperature measuring optical cable to the DTS host for temperature calibration, measure the change of the optical signal in the temperature measuring optical cable over time in the preset ambient temperature range without ice, perform temperature demodulation along the temperature measuring optical cable, and calculate the fiber temperature coefficient.

[0060] S4, low-power heating test: connect the DTS host, power control module and polymer heating film in sequence. When the ambient temperature is below 0°C, call the power control module to perform a low-power heating test, monitor the temperature rise rate of the fan blades when there is no ice, and record the temperature rise rate data of the fan blades when there is no ice.

[0061] S5, ice point determination: In low temperature, high humidity and ice-prone seasons, start the DTS host, use the temperature measuring optical cable to continuously monitor the temperature, and feed back the temperature monitoring results to the DTS host; when the temperature is detected to be lower than 0°C, call the power control module to use the preset test power to perform low-power active heating on the entire fan blade. The heating power is determined by the resistance of the polymer heating film and the area of ​​the single heating film. Detect the heating rate at different positions and compare it with the heating rate data of the un-iced fan blade recorded in step S4. According to the characteristic that the air heating rate is much higher than the ice under the same heating conditions, for the position point where the actual heating rate is lower than the un-iced heating rate and the rate difference is greater than the preset difference threshold, determine that ice is present at that position point;

[0062] S6, high-power heating and deicing: For locations with ice, call the power control module, combine the comparison results of the actual heating rate and the heating rate without ice, the size of the fan blades and the coverage area of ​​the polymer heating film, calculate the corresponding heating power, and call the polymer heating film for deicing. When the monitored ice point exists on the coverage area of ​​the heating film, start the heating film at the corresponding position for deicing; when the ice point appears in the gap without heating film coverage, select the adjacent heating film closest to the position and heat it for deicing; continue to monitor temperature changes, and when the temperature at the ice point is higher than the freezing point for a duration greater than the preset time threshold, stop heating and return to step S5.

[0063] For existing fan blades, it is required to lay loose tube temperature measuring optical cables and polymer heating films on the outer surface of the fan blades, and coat the outermost layer with polyurethane insulating coating to reduce the risk of lightning strikes; for newly built fan blades, temperature measuring optical cables and heating films can be pre-embedded during the manufacturing process to achieve one-piece molding, reduce the risk of damage and increase service life.

[0064] Fiber optic sensing technology detects the intensity, frequency, phase, polarization and other parameters of the transmitted light in the optical fiber to achieve online monitoring of various basic physical parameters such as body temperature, stress, vibration, etc. Distributed fiber optic sensing technology uses sensing optical cables as sensing sensitive elements and signal transmission media, combined with different signal demodulation equipment, to detect physical quantity information such as strain, temperature, vibration, etc. along the laying of sensing optical cables, and achieves a spatial resolution of meters at a sensing distance of tens of kilometers, providing a high-density, low-cost, long-distance distributed temperature monitoring solution for structural health monitoring, so it is very suitable for distributed temperature monitoring of large-scale infrastructure. At present, the commonly used distributed fiber optic sensing temperature sensing technologies mainly include Brillouin optical time domain reflectometry technology (BODTR), Raman optical time domain reflectometry technology (ROTDR) and Brillouin optical time domain analysis technology (BOTDA). In this embodiment, the DTS host can flexibly select Brillouin optical time domain reflectometry technology (BODTR), Raman optical time domain reflectometry technology (ROTDR) and Brillouin optical time domain analysis technology (BOTDA) to achieve temperature sensing according to the actual wiring situation and the use environment.

[0065] For example, the power control module can select thyristors to control the conduction time of the AC power supply according to actual needs to control the heating power, and can also realize the conversion of AC power into DC power, and realize power control by controlling the external voltage of the electric heating film. Since the polymer electric heating film is a planar conductive material, it forms a maximum heat conduction surface with the heated body. When powered on for heating, the heat can be quickly transferred to the heated body. It has the characteristics of stable structure, good processability, aging resistance, low attenuation, complex structural design, high conversion efficiency, and easy functional composite. By selecting a suitable matrix, it can have a good interface bonding force with the blade material. Therefore, the polymer electric heating film has great advantages in active anti-icing and de-icing wind turbine blades.

[0066] Examples

[0067] This example uses a 5kW wind turbine blade with a length of 2.65m, a wingspan of 0.3m at its widest point, a tip width of 0.13m, and a root thickness of 0.05m.

[0068] Polymer heating film is evenly laid on the windward side and leading edge of the fan blades, covering an area of Figure 2 As shown. In this experiment, thyristors are used for circuit control. The on and off time of the thyristor control circuit in each AC cycle is used to control the heating power. The advantage of using thyristors for circuit control is that it reduces the cost of the system and has a high cost performance ratio. At the same time, the structure is simple and easy to implement. Connect the polymer heating film to the parallel circuit, and connect it to the thyristor, power control module and 220V AC power supply. The circuit structure is shown in Figure 3 shown.

[0069] On the surface of the polymer heating film, the loose tube temperature measurement optical cable is arranged in an S-shaped coil and arranged along the length of the blade so that the optical fiber detection range includes all polymer heating films. After the arrangement is completed, epoxy resin is applied to the surface of the optical fiber to protect the optical fiber and reduce the air resistance when the blade rotates. Polyurethane coating is applied to reduce the risk of lightning strikes. The local position of the loose tube temperature measurement optical cable and the polymer heating film is shown in the figure below. Figure 4 shown.

[0070] After the installation of the loose tube temperature measurement optical cable and the polymer heating film is completed, a temperature calibration experiment is required. The optical cable is connected to the DTS host, and the change of the optical signal in the optical fiber over time in the absence of ice is measured. The temperature is demodulated along the sensing optical fiber, and the optical fiber temperature coefficient is calculated. Specifically, BOTDR was used in this experiment to measure the change of the optical fiber Brillouin frequency shift (BFS) over time in the absence of ice. The calibration system uses a high and low temperature alternating wet heat chamber, and the instrument temperature control accuracy is ±0.1℃. In the temperature calibration test, the temperature control range is -20℃~10℃, with a step size of 5℃. 10 sets of data are collected under each temperature condition, and the average value is taken as the Brillouin frequency shift value of the temperature section. The temperature coefficient is obtained by fitting the curve of the optical fiber temperature BFS and temperature change. The relationship between each module is as follows. Figure 5 shown.

[0071] In order to accurately determine the icing condition, it is required to conduct active heating experiments in the non-icing season. The selection of heating voltage is based on the formula

[0072]

[0073] Calculate, where P is power density, U is voltage, R is resistance, and S is the area of ​​a single polymer electric heating film. Connect the optical cable to the DTS host, heat at low power, detect the temperature rise rate of the fan blades when there is no ice, and record the data. Specifically, connect the optical cable to the DTS host and the power control module to heat the parallel circuit at low power. This experiment uses a 49V voltage for heating, detect the temperature rise rate of the fan blades when there is no ice, and record the data. Record the temperature rise rate curve when there is no ice by heating for a short time.

[0074] In the low temperature and high humidity icing season, temperature monitoring is carried out continuously. When the temperature is detected to be below 0°C, low-power active heating is carried out to detect the heating rate at different positions. The maximum temperature rise DT within 1 minute is calculated as:

[0075]

[0076] Among them, Q is the calorific value of the polymer heating film, SH is the specific heat of the heated material, De is the specific gravity of the heated material, and V is the volume. By taking into account the specific heat and specific gravity of air and ice, it can be obtained that when heated at the same volume and power, the temperature rise of air within 1 minute is 1478 times that of ice. Therefore, according to the characteristic that the air heating rate is much higher than that of ice under the same heating conditions, for the position point where the heating rate is significantly lower than the heating rate without ice, it is determined that ice is present at that location. After the detection is completed, the power control module is called to control the high-power heating of the polymer heating film closest to the ice-covered position. Continuously monitor the temperature changes. When the temperature at the ice-covered location is higher than 0°C after a period of time (such as 10 minutes), it is determined that the deicing is completed and the heating is stopped.

Claims

1. A self-feedback anti-icing and de-icing system for wind turbine blades based on a DTS system, characterized in that: The wind turbine blade self-feedback anti-icing and de-icing system includes a DTS host, a loose sleeve temperature measurement optical cable, a power control module and a polymer heating film; The polymer heating films are distributed and fixed on the fan blades by adhesive, and there are gaps between adjacent polymer heating films; all polymer heating films are connected in parallel to a power control module, and the power control module independently controls the working state of each polymer heating film; The loose tube temperature measurement optical cable is coiled in an S shape along the length direction of the blade on the surface of the polymer heating film away from the fan blade, so that the optical fiber detection range completely covers the gap between the polymer heating film and the polymer heating film; The DTS host is connected to the temperature measuring optical cable, and the DTS host is embedded with a temperature calibration module, a low-power heating test module, an ice point judgment module and a high-power deicing module; The temperature calibration module is used to measure the change of the optical signal in the temperature measuring optical cable over time without ice in the preset ambient temperature range, perform temperature demodulation along the temperature measuring optical cable, and calculate the optical fiber temperature coefficient; the preset ambient temperature range is -20°C to 10°C; The low-power heating test module is used to call the power control module to perform a low-power heating test when the ambient temperature is lower than 0°C, monitor the temperature rise rate of the fan blades when there is no ice, and record the temperature rise rate data of the fan blades when there is no ice; The ice point judgment module is used to start the DTS host in the low temperature, high humidity and easy ice season, and call the temperature measurement optical cable to continuously monitor the temperature; when the temperature is detected to be lower than 0°C, the power control module is called to use the preset test power to actively heat the entire fan blade at low power, detect the heating rate at different positions, and compare it with the locally recorded heating rate data of the fan blade without ice. For the position point where the actual heating rate is lower than the heating rate without ice, and the rate difference is greater than the preset difference threshold, it is determined that ice is present at the position point; The high-power heating and deicing module is used to call the power control module, and calculate the corresponding heating power based on the comparison results of the actual heating rate and the heating rate without ice, the size of the fan blades and the coverage area of ​​the polymer heating film. The polymer heating film corresponding to the ice-covered position is called to de-ice the ice-covered point using the calculated heating power, and the temperature changes are continuously monitored. When the temperature at the ice-covered position is higher than the freezing point for a period of time greater than a preset time threshold, the heating is stopped.

2. A self-feedback anti-icing and de-icing method for fan blades based on a DTS system, characterized in that: The self-feedback anti-icing and deicing method for fan blades is based on the self-feedback anti-icing and deicing system for fan blades according to claim 1; and comprises the following steps: S1, installing polymer heating films: using adhesive to distribute and fix multiple sheet-shaped polymer heating films on the fan blades, with gaps between adjacent polymer heating films, and minimizing the gaps while retaining the construction distance of the connection circuit; connecting the polymer heating films in parallel with the power control module, and using the power control module to independently control the working state of each polymer heating film; S2, laying out the temperature measuring optical cable: on the surface of the polymer heating film away from the fan blade, lay out the loose-sleeved temperature measuring optical cable in an S-shaped coil along the length direction of the blade, so that the optical fiber detection range completely covers the gap between the polymer heating film and the polymer heating film; S3, temperature calibration: connect the temperature measuring optical cable to the DTS host for temperature calibration, measure the change of the optical signal in the temperature measuring optical cable over time in the preset ambient temperature range without ice, perform temperature demodulation along the temperature measuring optical cable, and calculate the optical fiber temperature coefficient; S4, low-power heating test: connect the DTS host, power control module and polymer heating film in sequence. When the ambient temperature is below 0°C, call the power control module to perform a low-power heating test, monitor the fan blade heating rate when there is no ice, and record the fan blade heating rate data when there is no ice. S5, ice point determination: in low temperature, high humidity and ice-prone seasons, start the DTS host, use the temperature measuring optical cable to continuously monitor the temperature, and feed back the temperature monitoring results to the DTS host; when the temperature is detected to be lower than 0°C, call the power control module to use the preset test power to actively heat the entire fan blade at low power, and the heating power is determined by the resistance of the polymer heating film and the area of ​​the single heating film; detect the heating rate at different positions and compare it with the heating rate data of the fan blade without ice recorded in step S4. According to the characteristic that the air heating rate is much higher than the ice under the same heating conditions, for the position point where the actual heating rate is lower than the heating rate without ice, and the rate difference is greater than the preset difference threshold, it is determined that ice is present at the position point; S6, high-power heating for deicing: For locations with ice, call the power control module, combine the comparison results of the actual heating rate and the heating rate without ice, the size of the fan blades and the coverage area of ​​the polymer heating film, calculate the corresponding heating power, and call the polymer heating film for deicing; when the monitored ice point exists on the coverage area of ​​the heating film, start the heating film at the corresponding position for deicing; when the ice point appears in the gap not covered by the heating film, select the adjacent heating film closest to the position and heat it for deicing; continuously monitor the temperature change, when the temperature at the ice point is higher than the freezing point for a period of time greater than the preset time threshold, stop heating and return to step S5.

3. The wind turbine blade self-feedback anti-icing and de-icing method based on the DTS system according to claim 2 is characterized in that: In step S2, the surface of the temperature measuring optical cable is covered with epoxy resin to protect the optical fiber, while reducing the air resistance when the blades rotate; the outermost layer of the epoxy resin to protect the optical fiber is coated with polyurethane insulating coating.

4. The wind turbine blade self-feedback anti-icing and de-icing method based on the DTS system according to claim 2, characterized in that: The wind turbine blade self-feedback anti-icing and deicing method further comprises: The DTS host, temperature measuring optical cable, power control module and polymer heating film are powered by the hub power supply module inside the fan blade.

5. The wind turbine blade self-feedback anti-icing and de-icing method based on the DTS system according to claim 4, characterized in that: The wind turbine blade self-feedback anti-icing and deicing method further comprises: The heating power is controlled by controlling the conduction time of the AC power supply through thyristors and IGBTs.

6. The wind turbine blade self-feedback anti-icing and de-icing method based on the DTS system according to claim 4, characterized in that: The wind turbine blade self-feedback anti-icing and deicing method further comprises: The AC power output by the hub power supply module inside the fan blade is converted into DC power, and the power is controlled by controlling the applied voltage of the polymer heating film.

7. The wind turbine blade self-feedback anti-icing and de-icing method based on the DTS system according to claim 2, characterized in that: The DTS host selects one of the Brillouin optical time domain reflection technology, Raman optical time domain reflection technology and Brillouin optical time domain analysis technology according to the actual wiring situation and the use environment to measure the temperature distribution of the fan blades.

8. The wind turbine blade self-feedback anti-icing and de-icing method based on the DTS system according to claim 2, characterized in that: The preset ambient temperature range is -20°C to 10°C.

9. The wind turbine blade self-feedback anti-icing and de-icing method based on the DTS system according to claim 2, characterized in that: The wind turbine blade self-feedback anti-icing and deicing method further comprises: The temperature measuring optical cable and polymer heating film are pre-buried in the fan blades.

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