METHOD OF CONTROLLING A WIND TURBINE

Abstract

A method of controlling a wind turbine is provided including at least one fan-cooled unit with a fan adapted to circulate air inside a housing of the fan-cooled unit, which method includes operating the fan-cooled unit in a dryout mode by: disabling a thermal energy reduction the fan-cooled unit, which thermal energy reduction means is adapted to reduce thermal energy of air inside the housing during a normal operation mode of the fan-cooled unit; actuating a fan of the fan-cooled unit to circulate the quantity of air contained in the housing; and monitoring a climate parameter until a target climate condition has been reached. A wind turbine configured to execute the steps of the inventive method is also provided.

Claims

1. A method of controlling a wind turbine comprising at least one fan-cooled unit with a fan configured to circulate air inside a housing of the at least one fan-cooled unit, the method comprising operating the at least one fan-cooled unit in a dryout mode by: disabling a thermal energy reduction means of the at least one fan-cooled unit, the thermal energy reduction means configured to reduce thermal energy of air inside the housing during a normal operation mode of the at least one fan-cooled unit; actuating a fan of the at least one fan-cooled unit to circulate a quantity of air contained in the housing; and monitoring a climate parameter until a target climate condition has been reached.

2. The method according to claim 1, wherein the disabling the thermal energy reduction comprises closing an air exit opening in the housing of the at least one fan-cooled unit.

3. The method according to claim 1, wherein the disabling the thermal energy reduction comprises deactivating a fluid-to-air cooling circuit of the at least one fan-cooled unit.

4. A method according to claim 1, further comprising operating the fan of the least one fan-cooled unit at a maximum rotational speed during a dry-out procedure.

5. The method according to claim 1, wherein the target climate condition is a maximum relative humidity and/or a minimum temperature.

6. The method according to claim 1, further comprising a subsequent step of operating the at least fan-cooled unit in a normal mode when the target climate parameter has been reached.

7. The method according to the claim 6, wherein the operating the at least one fan-cooled unit in the normal mode comprises re-opening an air exit opening, activating a fluid-to-air cooling circuit, and/or reducing the rotational speed of the fan.

8. A wind turbine comprising: at least one fan-cooled unit comprising a fan arranged in an interior of a unit housing and a thermal energy reduction means configured to reduce thermal energy in air in the interior during a normal operation mode of the at least one fan-cooled unit; a sensor arrangement configured to monitor a climate parameter in a wind turbine nacelle; and a dry-out management module configured to receive a dry-out command, and to execute the method according to claim 1 to perform a dry-out procedure.

9. The wind turbine according to claim 8, wherein the thermal energy reduction comprises an air exit opening in the unit housing, and wherein the dry-out management module is configured to close the air exit opening during the dry-out procedure.

10. The wind turbine according to claim 9, wherein a cover of the air exit opening comprises an electromagnetic lock configured to engage with the unit housing of the at least one fan-cooled unit, and wherein the dry-out management module is configured to actuate the electromagnetic lock.

11. The wind turbine according to claim 8, wherein the at least one fan-cooled unit is an air-to-liquid heat-exchanger.

12. The wind turbine according to claim 11, wherein the thermal energy reduction means of the heat-exchanger comprises a fluid cooling circuit, and wherein the dry-out management module is configured to deactivate the fluid cooling circuit during the dry-out procedure.

13. The wind turbine according to claim 8, wherein the at least one fan-cooled unit is a ventilation unit.

14. The wind turbine according to claim 13, wherein the thermal energy reduction the ventilation unit comprises louvers, and wherein the dry-out management module is configured to close the louvers during the dry-out procedure.

15. A computer program product, comprising a computer readable hardware storage device having computer readable program code stored therein, the program code executable by a processor of a computer system to implement a method according to claim 1.

Description

BRIEF DESCRIPTION

[0028] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0029] FIG. 1 shows an embodiment of the inventive wind turbine:

[0030] FIG. 2 is a graph to illustrate the inventive method:

[0031] FIG. 3 is a flowchart to illustrate steps of the inventive method;

[0032] FIG. 4 illustrates a conventional approach; and

[0033] FIG. 5 shows components of a conventional wind turbine.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a simplified schematic representation of an exemplary embodiment of a wind turbine 1 according to embodiments of the invention. The diagram indicates only the aspects that are relative to embodiments of the invention and shows: a number of fan-cooled units 2 and a dry-out management module 1M. On the right, the diagram shows three fan-cooled units 2. Each fan-cooled unit 2 comprises a housing 20 enclosing a quantity of air 2.sub.air in its interior 200: one or more fans 2F disposed in the interior 200, and a removing thermal energy during normal operation of that unit 2. A fan-cooled unit 2 may also enclose one or more critical components that must be dry before being switched on. In descending order, these fan-cooled units 2 are: a cooling unit of a climate control arrangement: a wind turbine nacelle or wind turbine tower containing various electrical components (collectively referred to by the label 2C); and a forced ventilation unit 2. Each fan-cooled unit 2 includes one or more sensors S for monitoring climate parameters in the housing interior 200. The dry-out management module 1M may be realized as part of the wind turbine controller of the wind turbine 1, but is shown here as a functional module in order to explain embodiments of the invention.

[0035] The dry-out management module 1M is configured to receive a dry-out command 1 dryout after a prolonged off-grid state of the wind turbine 1, and to execute steps of the inventive method in order to perform a dry-out procedure.

[0036] In this exemplary embodiment, one fan-cooled unit 2 is an air-to-liquid heat-exchange unit or cooling unit, with a pump 2P that can transport cooling fluid through pipes of a cooling circuit 24. This cooling unit may be constructed to circulate air through the generator during normal operation in order to cool the armature and/or field windings (not shown). During normal operation of that unit 2, a fan 2F blows warm air (heated during normal operation of the wind turbine) over the pipes 24. The cooling fluid in the pipes absorbs heat from the airflow and transports the warmed fluid to an external heat exchanger 2X, for example arranged in a panel at the rear of the nacelle. The thermal energy extraction this fan-cooled unit is realized by the cooling circuit 24 and the motor-driven pump 2P, and the dry-out management module is configured to issue a control signal 2M.sub.off to switch the pump motor 2M off during the dry-out procedure. The dry-out management module 1M also issues a control signal 2F.sub.on to switch on the fan 2F during the dry-out procedure. After completion of the dryout procedure, the fan is operated in the normal manner, and the pump is restarted.

[0037] The second fan-cooled unit 2 in this example represents any component 2C that is enclosed in a housing 20 with an air exit opening 21, which can be closed by a cover 22 actuated by the dry-out management module 1M, and wherein a fan 2F is arranged in the housing interior 200 and controllable by the dry-out management module 1M. An example of such a housing 20 may be the nacelle, a section of the wind turbine tower, the hub, etc. Here, the dry-out management module 1M issues a control signal 2.sub.shut to close the cover 22 and a control signal 2F.sub.on to switch on the fan 2F during a dry-out procedure. After completion of the dryout procedure, the fan is no longer required, and the cover can be left open. In an exemplary embodiment, the moveable cover 22 can engage with the housing 20 by an electromagnetic lock, which can be actuated by a signal 2.sub.shut issued by the dry-out management module 1M.

[0038] The third fan-cooled unit 2 in this example is a ventilation unit 2 with two louvers 23 and a fan 2F that, during normal operation of the wind turbine, is used for forced ventilation of the nacelle interior. Here, the dry-out management module 1M issues a control signal 2.sub.shut to close both louvres 23 during the dry-out procedure and opened again afterwards. The dry-out management module 1M also issues a control signal 2F.sub.on to switch on the fan 2F of this unit during a dry-out procedure. After completion of the dryout procedure, the fan is operated in the normal manner, and the louvers are controlled accordingly.

[0039] During the dry-out procedure, the dry-out management module 1M can operate the fans 2F to turn at their highest speed. For example, a fan control signal 2F.sub.on may be a voltage reference that determines the fan speed. Because the unit housings are closed off (e.g., by control signals 2.sub.shut), the air inside each housing is heated by waste heat generated by the fan 2F, and also by the kinetic energy of the agitated air. As time passes, the heated air ensures that standing water evaporates from any surfaces inside the unit 2, and that the temperature of sensitive equipment 2C within the unit 2 is raised towards an acceptable level at which any critical components inside the unit 2 can be switched on.

[0040] Ultimately, an acceptable level of relative humidity and/or an acceptable temperature is reached, so that the dry-out procedure can conclude. The wind turbine may then be restarted safely. The dry-out management module 1M can then issue control signals to re-open previously closed covers 22, 23, and to allow the fans 2F to operate at a normal speed.

[0041] FIG. 2 illustrates the inventive method. After an off-grid mode M.sub.offgrid comes to an end at time to, and the wind turbine is once again connected to the grid (in mode M.sub.ongrid), the inventive method is initiated by setting a dry-out flag I.sub.dryout (this can be done by the wind turbine controller, for example). The dry-out management module 1M then issues one or more signals to close off the housings of one or more fan-cooled units 2. Each fan-cooled unit 2 will now be operated in a dry-out mode 2.sub.dryout. The dry-out management module 1M also issues suitable fan control signals 2F.sub.on to switch on the fans 210. These can be controlled to raise the rotational speed .sub.2F to a maximum .sub.max as shown here. The dry-out management module 1M also issues a motor control signal 2M.sub.off to keep the motor 2M of a fluid circuit pump 2P in its off state. With these control measures, the fan action causes the air temperature in the unit housings to increase, raising the air temperature and evaporating any standing water. The air temperature in the fan-cooled units 2 will ultimately reach a target minimum T.sub.min, and the relative humidity RH.sub.12 in the fan-cooled units 2 will ultimately drop to a target maximum RH.sub.max. At this time t.sub.OK, the dry-out procedure can be deemed complete, and the wind turbine may be restarted. Any cooling unit that was operated as a fan-cooled unit during dryout can then resume operation in its normal mode 2.sub.normal.

[0042] FIG. 3 is a flowchart to illustrate the method steps. In a first step 30, a dry-out flag I.sub.dryout is set to initiate the dry-out procedure. In step 31, the dry-out management module then issues signals 2.sub.shut, 2F.sub.on, 2M.sub.off to close the air exit openings of any fan-cooled unit, to switch on the fans in the fan-cooled unit(s), and to switch off a pump motor of any fluid cooling circuit. In a next step 32, a measured parameter is compared to a target parameter (the relative humidity RH in the interior 200 of a fan-cooled unit 2, for example). The dry-out mode persists until the measured parameter has reached the target parameter. The dry-out procedure then concludes in step 33, and the dry-out management module clears the control signals as appropriate.

[0043] FIG. 4 illustrates a conventional art approach. After an off-grid mode M.sub.offgrid comes to an end at time to, and the wind turbine is once again connected to the grid, the conventional art control method commences with a dry-out procedure (indicated by setting a flag I.sub.dryout for example) that persists until a fixed dry-out duration has elapsed. This can extend over several days, for example 72 hours, terminating here at time t.sub.fixed, when the dry-out procedure is deemed complete and the wind turbine may be restarted. However, the temperature Tint and relative humidity RH.sub.int in the nacelle may have reached a suitable levels T.sub.min, RH.sub.max some time previously, indicated here at time t.sub.OK. Therefore, the wind turbine could have been started at time t.sub.OK instead of the later time t.sub.fixed, and revenue has been lost in the intervening time D.sub.wait.

[0044] FIG. 5 shows a number of heaters 51 installed within housings of temperature-sensitive components 5C of a conventional art wind turbine 5. The heaters 51 are switched on when the wind turbine controller 52 detects the on-grid state, so that dry-out can be performed. While the heaters 51 can permit a shorter fixed dryout duration, the need to include heaters 51 adds to the overall cost of manufacture and maintenance. As described in FIG. 4 above, the dry-out procedure is performed for a set duration, for example 48 hours, but satisfactory startup conditions may be reached several hours before the predetermined duration elapses and remain undetected. Here also, potential revenue may be lost.

[0045] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of embodiments of the invention. For example, any wind turbine component that requires dry starting conditions but is not already enclosed in the housing of a fan-cooled unit may be adapted to benefit from the inventive method. This can be done by constructing a suitable housing (with one or more actuatable apertures) to enclose the component and by arranging one or more fans in the housing interior, so that the fans can be actuated by the dry-out management module. Particularly in the case of a large interior such as the interior of a large nacelle, or the interior of a tower, the cost of adapting a component as a fan-cooled unit may be insignificant compared to the benefits of a short dry-out procedure and the attendant gain in revenue.

[0046] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.