Method of operating cooling system in nacelle of wind turbine and wind turbine

Abstract

Method for operating a cooling system (12) in a nacelle (9) of a wind turbine (1) wherein the wind turbine (1) comprises a generator (5) and at least one transformer (11) positioned in the nacelle (9) wherein the cooling system (12) comprises: an air cooling subsystem (14) for cooling at least the generator (5), the air cooling subsystem comprises an inflow unit (15) for drawing inflow ambient air (36) into the nacelle (9); a temperature sensor (33, 34, 35) for measuring the temperature of the ambient air and at least one temperature in the nacelle (9); and a control device (31) for controlling the operation of the cooling system (12) using the measured temperature, where the control device (31) performs the following: determining a temperature difference between the ambient air and at least part of the component in the nacelle (9) from the measured temperature values of the temperature sensors (33, 34, 35); and controlling the cooling system (12) to reconcile the inflow ambient air (36) by exchanging heat between the at least one component in the nacelle (9) and the ambient air to reduce the temperature difference when the temperature difference satisfies an exchange criterion indicating a possible condensation of the air humidity on the at least one of the portions of the component in the nacelle (9).

Description

Technical Field

[0001] The present invention relates to a method for operating a cooling system in a nacelle of a wind turbine, wherein the wind turbine comprises a generator and at least one transformer positioned in the nacelle, wherein the cooling system comprises: - an air cooling subsystem for cooling at least the generator, the air cooling subsystem comprising an inflow unit for drawing inflow ambient air into the nacelle, a temperature sensor for measuring the temperature of the ambient air and at least one temperature in the cabin, and - A control device for controlling the operation of the cooling system using the measured temperature.

[0002] The invention further relates to a wind turbine, wherein such a method is implemented. Background Art

[0003] Wind turbines are well known and can be used, for example, as a source of renewable energy. A typical wind turbine includes a plurality of wind turbine blades mounted to a rotor hub. The rotor hub is coupled to a rotor of a generator housed in the wind turbine's nacelle, which is typically located atop a tower. Other equipment, such as converters, transformers, and electrical cabinets, is also typically housed in the nacelle. The generator and other components (such as the transformer) heat up during use and therefore require cooling.

[0004] Cooling systems that use ambient air to cool generators have been proposed in the prior art. Here, air is drawn into the nacelle through an inlet unit that includes at least one opening to direct ambient air into the nacelle. Typically, a blower / ventilator is used to blow air toward the generator components to be cooled (e.g., winding overhangs) and / or through the air gap between the rotor and stator. In some configurations, in addition to the air cooling subsystem, a liquid-based cooling subsystem (liquid cooling subsystem) using a liquid coolant can be provided, for example, to cool transformers, converters, or other components. Of course, the air cooling subsystem can also cool other components, such as electrical cabinets.

[0005] EP2806542A1 discloses an air flow control arrangement for a direct-drive wind turbine having a generator comprising a rotor and a stator. An inflow fan can be used to draw air into the interior of the nacelle. An outflow fan generates suction to draw air through gaps between the generator's winding overhangs and through air gaps between the generator's magnet poles and windings. The air exits the nacelle via an exhaust duct.

[0006] EP3279469A1 discloses a wind turbine with improved cooling. Here, a cooling system for cooling the generator is provided, wherein cooling air can be drawn in through the front assembly air inlet, but can also be drawn in from the tower. The tower air can be used in particular to reduce the humidity of the cooling air.

[0007] Nacelles with openings to the ambient air can be problematic when the wind turbine is not in operation, as temperature fluctuations in the nacelle and its components lead to the risk of condensation of moist air inside the nacelle and generator. In particular, when the dew point (which depends on the pressure, humidity, and temperature of the air, as well as corresponding condensation-sensitive structures) is exceeded, water can condense, potentially leading to corrosion and increasing the risk of short circuits in the electrical system. While the temperature of the ambient air depends on climatic parameters and varies throughout the day, the temperature in the nacelle (particularly that of condensation-sensitive structures) also depends on the amount of heat or cold stored in the wind turbine. For example, transformers may contain large amounts of oil, which keeps nacelle components warm after shutdown or cool during the twilight hours when the ambient air has already warmed. To address this issue, dehumidification of the incoming ambient air, particularly in the inlet unit of the air cooling subsystem, has been proposed, for example by removing water during the dehumidification process. Summary of the Invention

[0008] It is an object of the present invention to provide an improved operation of a cooling system in a wind turbine, in particular with regard to condensation and / or when no energy is being produced in the wind turbine.

[0009] This object is achieved by providing a method and a wind turbine according to the independent claims. Advantageous embodiments are described by the dependent claims.

[0010] In the method as initially described, in the control device, according to the invention, the following steps are performed: - determining a temperature difference between the ambient air and at least part of the component in the nacelle from the measured temperature values ​​of the temperature sensor, and When the temperature difference satisfies an exchange criterion indicating possible condensation of air humidity on at least one portion of a component in the nacelle, controlling the cooling system to condition the inflowing ambient air by exchanging heat between the at least one component in the nacelle and the ambient air to reduce the temperature difference.

[0011] This conditioning (i.e., warming or cooling the incoming ambient air) can be performed until the exchange criterion or the stop criterion is no longer met. Most preferably, the conditioning of the ambient air depending on the temperature difference is performed only when the wind turbine is shut down, in particular when the generator is not converting mechanical energy from the wind into electrical energy. Therefore, the proposed method can be most advantageously applied in situations where the wind turbine is not in operation and is exposed to a higher risk of condensation.

[0012] The main concept of the present disclosure is to condition the ambient air drawn into the nacelle using heat sources or heat sinks present in the nacelle to reduce the temperature difference between the ambient air and components within the wind turbine nacelle, particularly condensation-sensitive structures such as steel structures. These condensation-sensitive structures may be part of the components and / or comprised by parts of the components. Condensation on these condensation-sensitive structures within the nacelle can be prevented by controlling the temperature difference between these structures and the internal air / air flow. This control is based on temperature measurements and, preferably, also relative humidity measurements. In particular, the water content of the ambient air is taken into account and condensation is prevented by controlling the temperature difference between the air within the nacelle and the structures within the nacelle. In particular, the exchange criterion may include a temperature difference greater than at least one threshold value, particularly 10 to 12 Kelvin, for example, 11 Kelvin. The threshold value or threshold values ​​applied here (which may differ depending on whether the ambient air or the structure is warmer) may be empirically derived and indicate the likelihood of a relevant heat exchange. In particular, in embodiments, the threshold value may be determined dynamically, for example, taking into account relative humidity measurements and / or other relevant parameters. However, in preferred embodiments, it may be sufficient to select the threshold value based on an approximate and / or empirical selection. 11K (or 11°C) has been shown to be a good approximation.

[0013] Note that in this case, while condensation will primarily occur on cool surfaces of structures exposed to the warmer incoming ambient air, heating the incoming ambient air serves to keep the nacelle and its components generally warmer for a longer period of time, thereby preventing condensation-sensitive structures from cooling for a longer period of time. In the second scenario, cooling the incoming ambient air causes condensation where heat is extracted, thereby dehumidifying the incoming ambient air. On the other hand, the temperature difference between the air and condensation-sensitive structures decreases, resulting in less localized, intense condensation. Thus, both effects serve to prevent condensation on cooler structures. Thus, in both cases, the properties of the nacelle's components as both a heat source / sink and a heat sink are exploited to reduce condensation.

[0014] It should be noted that a wind turbine can have a generally known structure, including a plurality of wind turbine blades mounted to a rotor hub, which is coupled to a rotor of a generator in a nacelle. The nacelle can be positioned atop a tower of the wind turbine. The wind turbine can be a direct-drive wind turbine. Furthermore, other components in the nacelle, such as electrical cabinets, converters, bearings, etc., can also be cooled by a cooling system.

[0015] In a particularly preferred embodiment, heat for conditioning the incoming ambient air can be provided from or to the at least one transformer, in particular from or to the oil in the transformer. In other words, the energy stored in the transformer can be used as a source for heating the incoming ambient air, while during cooling, the transformer, acting as a heat sink, can also absorb heat from the incoming ambient air. In one embodiment, the at least one transformer of the wind turbine can include a large volume of oil with a high heat capacity. In one embodiment, a heat pump can advantageously be used between the preheating device and the transformer, in particular the transformer oil, to further improve conditioning options and efficiency.

[0016] In a particularly advantageous embodiment, the cooling system may further comprise: a liquid cooling subsystem using a liquid coolant for cooling at least the transformer, said liquid cooling subsystem comprising at least one pumping and / or distribution unit for the coolant, a cooling device for cooling said coolant, and coolant pipes forming a cooling circuit for the coolant, and - a preheating device positioned in the inflow unit or directly downstream of the inflow unit for heat exchange between the inflowing ambient air and the liquid coolant, The control device controls the cooling system to use the preheating device to condition the inflowing ambient air.

[0017] Therefore, it is proposed to use a liquid cooling subsystem, which can use water as the coolant, to transport heat between the transformer (and optionally other components) and the inflow unit. Heat stored in the transformer and transferred to the coolant can then be transferred to a preheating device, where it can be transferred to the incoming ambient air. Conversely, heat from the incoming ambient air can be transferred to the coolant in the preheating device and then to the transformer, where a corresponding reservoir is present, thereby reducing temperature differences. In a specific embodiment, the preheating device can include a heat exchanger.

[0018] In a specific example, if the wind turbine has just been shut down, heat remains stored in the transformer, particularly in its oil. However, the ambient temperature may be very cold. Here, this heat can be transferred to the coolant and actively used to warm the incoming ambient air and maintain a relatively high temperature in the nacelle's air and structures. On the other hand, if, for example, the nacelle, transformer, and other components are still very cold after dark when the wind turbine is not in operation, extracting heat energy from the incoming ambient air in the preheating device can keep the incoming ambient air temperature low, particularly by causing condensation and thus reducing the humidity in the incoming ambient air. In particular, the preheating device will be cold, and the incoming ambient air will have a higher temperature. This provides another advantageous effect of the present invention: the condensation that occurs in the preheating device reduces the relative humidity of the incoming ambient air.

[0019] Preferably, the liquid cooling subsystem can include a subcircuit comprising a preheating device and a heat exchanger for the transformer, in particular transformer oil, wherein the control device controls the liquid cooling subsystem so that the coolant circulates at least in the subcircuit, in particular only in the subcircuit. For example, a pumping and / or distribution unit for the coolant can be controlled accordingly. Of course, such a subcircuit can also include connections to other components to be cooled near the transformer (e.g., at least one converter). However, even in this case, the operation of other devices and subcircuits of the liquid cooling subsystem, such as components to be cooled located elsewhere, an expansion tank, and / or a cooling tower, is not required for the described heat transfer.

[0020] In an embodiment, the nacelle may include at least two transformers, wherein a liquid cooling subsystem and corresponding preheating device are provided for each transformer and controlled by the control device to condition the inflowing ambient air. Here, during the control, temperature differences between the two transformers, etc. may also be taken into account.

[0021] In a preferred embodiment, in addition to conditioning the incoming ambient air, the cooling system can also be controlled to condition at least one condensation-sensitive structure (particularly a steel structure) in the nacelle, particularly to at least approximately match the temperature of multiple condensation-sensitive structures, particularly in the shut-down state. If the condensation-sensitive structure is part of the cooling system (particularly a liquid cooling subsystem) or is cooled by another component of the cooling system (particularly a liquid cooling subsystem), corresponding configurations used in normal cooling system operation and known from the prior art can also be used to condition the corresponding condensation-sensitive structure. For other condensation-sensitive structures, corresponding cooling measures can be provided. For example, to accommodate or stabilize the structure, cooling channels can be provided in the liquid cooling subsystem so that coolant can flow through the structure. By directly heating the condensation-sensitive structure (particularly a steel structure) through the coolant circulation, excessive local temperature differences in the nacelle that could lead to condensation can be more reliably prevented. For example, some condensation-sensitive structures may be further away from the transformer (which may itself be or include a condensation-sensitive structure) and therefore be substantially cooler. By controlling the cooling system to increase the temperature of the condensation-sensitive structure (particularly the steel structure), the control objective of reducing and, in particular, even preventing condensation can be better achieved.

[0022] The invention further relates to a wind turbine comprising a nacelle with a cooling system, at least one transformer and a generator, wherein the cooling system comprises: - an air cooling subsystem for cooling at least the generator, said air cooling subsystem comprising an inflow unit for drawing inflow ambient air into the nacelle, a temperature sensor for measuring the temperature of the ambient air and at least one temperature in the cabin, and - a control device that uses the measured temperature to control the operation of the cooling system, Therein, the control device is configured to execute the method according to the present invention.

[0023] All comments and features regarding the method according to the invention apply analogously to the wind turbine according to the invention, so that the same advantages can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. However, the drawings are only schematic diagrams designed only for illustrative purposes and do not limit the present invention. The drawings show: Figure 1 A wind turbine according to the invention is shown, Figure 2 a functional diagram showing components in the nacelle of the wind turbine, Figure 3 A flow chart showing a method according to the present invention is shown, Figure 4 shows a first possible flow of heat in a first condition, and Figure 5 A second possible flow of heat in a second condition is shown. DETAILED DESCRIPTION

[0025] Figure 1 is a schematic diagram of a wind turbine 1 according to the present invention. The wind turbine 1 comprises a plurality of wind turbine blades 2, in this case three wind turbine blades, mounted to a rotor hub 3, which is coupled to an outer rotor 4 of a generator 5 of the wind turbine 1. In this case, the wind turbine 1 is a direct-drive wind turbine. In the generator 5, an outer rotor 4, comprising at least one permanent magnet 6, rotates around an inner stator 7 having corresponding stator windings 8.

[0026] The generator 5 is housed in a nacelle 9, where other components, such as a converter 10 and in this case two transformers 11, are also located. Of course, the nacelle 9 will also house other components, such as electrical cabinets and electrical conduits connecting the components.

[0027] The generator 5 , the converter 10 , the transformer 11 and other components in the nacelle 9 need to be cooled, so the nacelle 9 further includes a cooling system 12 .

[0028] In this case, mechanical energy from the wind turbine blades 2 and rotor 4 is converted into electrical energy by a generator 5 and conditioned for input into the grid by a converter 10 and transformer 11. Connection to the grid is achieved via a tower 13 carrying the nacelle 9.

[0029] Figure 2A functional diagram shows a cooling system 12 and some of the components cooled in the nacelle 9. The cooling system 12 includes an air cooling subsystem 14 having an inflow unit 15 for drawing ambient air into the nacelle 9 according to arrow 16. In some embodiments, the inflow unit 15 may include at least one filter and / or at least one dehumidifier. The inflowing ambient air is then used, for example, using a blower / ventilator, to cool the generator 5. Specifically, it is drawn along the overhang of the stator coils 8 and / or through the air gap between the rotor 4 and the stator 7 before being discharged back into the environment according to arrow 17. According to arrow 19, the inflowing ambient air can also be used to cool other components 18, such as electrical conduits and / or electrical cabinets. While in the nacelle, the inflowing ambient air naturally also comes into contact with other components, particularly components including condensation-sensitive structures, as exemplified by arrow 20 for the transformer 11.

[0030] For each transformer 11, particularly those located on opposite sides of the nacelle 9, the cooling system 12 further includes a liquid cooling subsystem 21 that uses a liquid coolant, such as water, to cool the transformer 11 and other components, including the converter 10. Each liquid cooling subsystem includes a pumping and / or distribution unit 22 for circulating the coolant through coolant pipes in a corresponding sub-circuit and / or to and from a cooling device 23, in this case a cooling tower 24 and / or an expansion tank 25. One sub-circuit 26 may be provided to cool components 27 in the front portion of the nacelle 9, such as the bearings of the rotor, while another sub-circuit 28 is connected to heat exchangers (not shown) for the respective transformer 11 and converter 10. It should be noted that, particularly if a segmented stator 7 is used, multiple converters 10 may be provided and distributed for cooling between the liquid cooling subsystems 21.

[0031] The sub-circuit 28 also includes a preheating device 29 flowing into the unit 15, which has a heat exchanger 30 for exchanging heat between the coolant in the sub-circuit 28 and the inflowing ambient air. It is noted that, in addition or as an alternative, a heat pump can be provided between the respective transformer 11 and the preheating device 29.

[0032] The control unit 31 is configured to control the operation of the cooling system 12, in particular based on data from temperature sensors 32, 33, and 34. The temperature sensor 32 measures the temperature of the ambient air outside the nacelle 9 and may also provide a measurement of relative humidity. The temperature sensor 33 measures the temperature of components in the nacelle, in particular condensation-sensitive structures, which in this example are primarily steel structures. The temperature sensor 34 measures the coolant temperature, in particular at the inflow and / or outflow of the coolant in the unit 22, in this case primarily located in the pumping and / or distribution unit 22.

[0033] While control unit 31 is generally configured to control the normal operation of cooling system 12 during normal operation of wind turbine 1, in this case, the control unit is also configured to prevent condensation, particularly when no electrical energy is being generated. Here, the temperature values ​​measured by temperature sensors 32, 33, and / or 34 are used to determine the temperature difference between the ambient air and condensation-sensitive structures in nacelle 9, and when an exchange criterion is met, preheating device 29 is used to reduce the temperature difference. In other words, control unit 31 is configured to carry out the method according to the present invention.

[0034] The flowchart of this method according to the present invention is Figure 3 is shown in FIG. In step S1, as already explained, the temperature difference between the ambient air and at least some of the components in the nacelle (particularly their condensation-sensitive structures) is determined from the temperature values ​​measured by temperature sensors 32, 33, and 34. In step S2, the temperature difference is evaluated using an exchange criterion that indicates the exchangeability of heat between the incoming ambient air and the components in the nacelle 9, particularly the transformer 11. The temperature difference can be compared with a threshold value. The threshold value can be a fixed, empirically determined value, such as 11 K / 11°C, but can also be determined, for example, based on air humidity information from sensor 32 or other sensors configured to provide air humidity information.

[0035] When the switching criterion is not satisfied, the process returns to step S1.

[0036] However, if the exchange criteria in step S2 are met, then in step S3, cooling system 12 is controlled by control device 31 to use preheating device 29 to reduce this temperature difference with respect to the inflowing ambient air. Here, the coolant circulates through sub-circuit 28, particularly because transformer 11 (which itself includes at least one condensation-sensitive structure) serves as a heat reservoir. In particular, the oil contained in transformer 11 has a very high heat capacity. Therefore, the coolant circulating in sub-circuit 28 can transfer heat from transformer 11 to the inflowing ambient air, and vice versa, via preheating device 29. In particular, in the first case, when transformer 11 is still very warm compared to the ambient air, liquid cooling subsystem 21 can be controlled to also heat other condensation-sensitive structures of other components in nacelle 9 to maintain a high temperature for all of these condensation-sensitive structures.

[0037] In step S4, it is checked whether the switching criterion is still satisfied or whether the stopping criterion is not satisfied. When the stopping criterion is not satisfied and / or the switching criterion is still satisfied, the process returns to step S3, otherwise it returns to step S1.

[0038] In any case, in step S3 , the goal of the control is to reduce or even prevent condensation inside the nacelle 9 .

[0039] Figure 4 and Figure 5 Explain two situations. Figure 4 In the first scenario, wind turbine 1 has been shut down a short time ago, leaving components in nacelle 9 (particularly transformer 11) still hot. Therefore, to reduce the temperature difference between the incoming ambient air and the condensation-sensitive components, heat from transformer 11, which itself includes at least one condensation-sensitive structure 35, is transferred to the incoming ambient air 36 via preheating device 29. This keeps the air inside nacelle 9 warm. Furthermore, heat is transferred to other condensation-sensitive structures 37, which have been cooled further. Overall, this keeps nacelle 9 and its components warmer for longer and prevents condensation.

[0040] Figure 5 A second situation arises, in which condensation-sensitive structures 35, 37 are cooler than ambient air 36. In this case, heat is transferred from ambient air 36 to transformer 11, thereby reducing the temperature differential. In this second situation, preheating device 29 (particularly heat exchanger 30) is also cool, causing condensation to occur in preheating device 29, significantly reducing the relative humidity of the incoming ambient air before it enters the nacelle, thereby reducing condensation. Due to the reduced temperature differential between the air and structures 35, 37, localized condensation on cold structures 35, 37 is also reduced.

[0041] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art will be able to derive other variations from the examples without departing from the scope of the present invention.

[0042] Independent of grammatical term usage, individuals having either masculine or feminine identities are included within the term.

Claims

1. A method for operating a cooling system (12) in a nacelle (9) of a wind turbine (1), wherein: The wind turbine (1) comprises a generator (5) and at least one transformer (11) positioned in the nacelle (9), wherein the cooling system (12) comprises: an air cooling subsystem (14) for cooling at least the generator (5), the air cooling subsystem (14) comprising an inflow unit (15) for drawing inflow ambient air (36) into the nacelle (9), - a temperature sensor (33, 34, 35) for measuring the temperature of the ambient air and at least one temperature in the cabin (9), and - a control device (31) for controlling the operation of the cooling system (12) using the measured temperature, characterized in that the following operations are performed by the control device (31): - determining a temperature difference between the ambient air and at least part of the components in the nacelle (9) from the measured temperature values ​​of the temperature sensors (33, 34, 35), and - when the temperature difference satisfies an exchange criterion indicating a possible heat exchange between the inflowing ambient air (36) and at least one component in the nacelle (9), controlling the cooling system (12) to condition the inflowing ambient air (36) by exchanging heat between at least one component in the nacelle (9) and the ambient air to reduce the temperature difference.

2. The method according to claim 1, characterized in that The switching criteria include the temperature difference being greater than at least one threshold value.

3. The method according to claim 1 or 2, characterized in that Heat for conditioning the inflowing ambient air (36) is provided from or to the transformer (11), in particular from or to the oil in the transformer (11).

4. The method according to any one of the preceding claims, characterized in that The cooling system (12) further comprises: a liquid cooling subsystem (31) using a liquid coolant, said liquid cooling subsystem being used to cool at least said transformer (11), and comprising at least one pumping and / or distribution unit (22) for said coolant, a cooling device (23) for cooling said coolant, and coolant pipes forming a cooling circuit for said coolant, and a preheating device (29) positioned in the inflow unit (15) or directly downstream of the inflow unit (15), the preheating device being used for heat exchange between the inflowing ambient air (36) and the liquid coolant, The control device (31) controls the cooling system (12) to condition the inflowing ambient air (36) using the preheating device (29).

5. The method according to claim 4, characterized in that The preheating device (29) comprises a heat exchanger (30).

6. The method according to claim 4 or 5, characterized in that The liquid cooling subsystem (21) comprises a subcircuit (28), the subcircuit (28) comprising the preheating device (29) and a heat exchanger leading to the transformer (11), the heat exchanger being in particular transformer oil, wherein the control device (31) controls the liquid cooling subsystem (21) so that the cooling liquid circulates at least in the subcircuit (28).

7. The method according to any one of claims 4 to 6, characterized in that The nacelle (9) comprises at least two transformers (11), wherein a liquid cooling subsystem (21) and a corresponding preheating device (29) are provided for each transformer (11) and are controlled by the control device (31) to condition the inflowing ambient air (36).

8. The method according to any one of the preceding claims, characterized in that In particular, in the closed state, in addition to conditioning the inflowing ambient air (36), at least one condensation-sensitive structure (35, 37), in particular a steel structure, in the nacelle (9) is conditioned by controlling the cooling system (12), in particular to at least approximately match the temperature of a plurality of the condensation-sensitive structures (35, 37).

9. The method according to any one of the preceding claims, characterized in that The conditioning of the ambient air depending on the temperature difference is performed when the wind turbine (1) is switched off, in particular only when the wind turbine (1) is switched off, in particular when the wind turbine is unable to convert mechanical energy from the wind into electrical energy via the generator (5).

10. A wind turbine (1) comprising a nacelle (9) with a cooling system (12), at least one transformer (11) and a generator (5), wherein: The cooling system (12) comprises: - an air cooling subsystem (14) for cooling at least the generator (5), said air cooling subsystem comprising an inflow unit (15) for drawing inflowing ambient air (36) into the nacelle (9), - a temperature sensor (33, 34, 35) for measuring the temperature of the ambient air and at least one temperature in the cabin (9), and - a control device (31) for controlling the operation of the cooling system (12) using the measured temperature, Characterized in that the control device (31) is configured to carry out the method according to any one of the preceding claims.

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