AUXILIARY POWER SUPPLY

Abstract

An auxiliary power supply arrangement of a wind turbine is provided, including a standby power supply configured to cover the average power requirements of auxiliary devices of the wind turbine; and an energy storage unit, which energy storage unit is configured to cover transient power requirements of the auxiliary devices and/or to supplement the standby power supply in covering the transient power requirements of the auxiliary devices. Also provided is a wind turbine including such an auxiliary power supply arrangement adapted to supply power to auxiliary devices of the wind turbine during an off-grid state of the wind turbine; and a method of operating such a wind turbine.

Claims

1-15. (canceled)

16. An auxiliary power supply arrangement of a wind turbine, comprising: a standby power supply configured to cover the average power requirements of auxiliary devices of the wind turbine; and an energy storage unit, which energy storage unit is configured to cover transient power requirements of the auxiliary devices and/or to supplement the standby power supply in covering the transient power requirements of the auxiliary devices, wherein the auxiliary devices are permanently installed devices and/or devices required temporarily during stages of installation, commissioning, or maintenance.

17. The auxiliary power supply arrangement according to claim 16, wherein the energy storage unit is a rechargeable energy storage module.

18. The auxiliary power supply arrangement according to claim 17, wherein the energy storage unit comprises any of: a lithium-ion battery, a supercapacitor arrangement.

19. The auxiliary power supply arrangement according to claim 16, wherein the energy storage unit has an energy storage capacity in the order of 5 kWh-1 MWh and a rated power output in the order of 50 kVA-400 kVA.

20. The auxiliary power supply arrangement according to claim 16, wherein the standby power supply generates power from a renewable energy source.

21. The auxiliary power supply arrangement according to claim 16, wherein the standby power supply comprises any of: a photovoltaic arrangement, a gas turbine, a fuel cell, a wave energy converter, a compressed-air energy storage module, a diesel generator.

22. The auxiliary power supply arrangement according to claim 16, wherein the energy storage unit and the standby power supply are connected in an inline arrangement.

23. The auxiliary power supply arrangement according to claim 16, wherein the energy storage unit and the standby power supply are connected in a line-interactive arrangement.

24. A wind turbine comprising: an aerodynamic rotor mounted to a hub; a nacelle mounted on a tower; a generator arranged in the nacelle; a number of auxiliary devices; and an auxiliary power supply arrangement according to claim 16 configured to supply power to the auxiliary devices during an off-grid state of the wind turbine.

25. The wind turbine according to claim 24, wherein the capacity of the standby power supply of the auxiliary power supply arrangement is at most 20% of the capacity of a conventional art standby power supply required to provide power to the auxiliary devices.

26. The wind turbine according to claim 24, comprising a monitoring unit configured to monitor power consumed by the auxiliary devices.

27. The wind turbine according to claim 26, comprising a monitoring unit configured to control the operation of an auxiliary device on the basis of data provided by the monitoring unit.

28. A method of operating a wind turbine according to claim 24, comprising: detecting an off-grid state; controlling the standby power supply of the auxiliary power supply arrangement to cover the average power requirements of the auxiliary devices; and discharging the energy storage unit to cover transient power requirements of the auxiliary devices.

29. The method according to claim 28, comprising recharging the energy storage unit from the standby power supply.

30. The method according to claim 28, wherein the energy storage unit is recharged when power consumption of the auxiliary devices is below the output power capacity of the standby power supply.

Description

[0030] Other objects and features of the present invention will become apparent from the following detailed descriptions considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for the purposes of illustration and not as a definition of the limits of the invention.

[0031] FIGS. 1-3 show an offshore wind turbine equipped with an auxiliary power supply arrangement according to the invention;

[0032] FIG. 4 shows an embodiment of the inventive auxiliary power supply arrangement;

[0033] FIGS. 5-6 show alternative configurations of the auxiliary power supply arrangement according to the invention;

[0034] FIG. 7 shows power provided to the auxiliary devices of a wind turbine equipped with an embodiment of the inventive auxiliary power supply arrangement;

[0035] FIG. 8 shows a wind turbine equipped with a prior art standby power supply;

[0036] FIG. 9 shows power supply to the auxiliary devices of the wind turbine of FIG. 8;

[0037] FIG. 10 shows a further embodiment of the invention

[0038] In the diagrams, like numbers refer to like objects throughout. Objects in the diagrams are not necessarily drawn to scale.

[0039] FIGS. 1-3 show an offshore wind turbine 2 equipped with an auxiliary power supply arrangement 1 according to the invention. In each case, the auxiliary power supply arrangement 1 comprises a standby power supply 1S configured to supply the average power required by auxiliary devices 2.sub.aux of the wind turbine 2, and an energy storage unit 1E configured to supply peak power, or supplement the supply of peak power required by the auxiliary devices 1E. The auxiliary devices 2.sub.aux can be permanently installed device such as yaw motors, pitch motors, climate control arrangement etc., or temporarily required tools and/or equipment, and can be distributed in various locations throughout the wind turbine 2, for example inside the nacelle 20, in the hub 21, in the tower, on a tower platform, etc. In FIG. 1, the standby power supply 1S is located on an external platform 23, and can be a diesel genset for example. The energy storage unit 1E is arranged on a platform 220 in the tower 22. The standby power supply 1S and the energy storage unit 1E are connected by a socket 11. In FIG. 2, the standby power supply 1S is a wave power device secured to a supporting structure of the wind turbine. Here, the energy storage unit 1E is arranged inside the nacelle 20, and the auxiliary power supply arrangement 1 provides power to the same arrangement of auxiliary devices 2.sub.aux (not shown). In FIG. 3, the standby power supply 1S is arranged on top of the nacelle, and can be a photovoltaic module. The standby power supply 1S, as explained above, can comprise one or more modules that collectively provide standby power to the auxiliaries.

[0040] In any of the above configurations, the energy storage unit 1E can be a battery such as a lithium-ion battery, and can be located as indicated in the tower interior or inside the nacelle 20. The devices are connected by means of a socket 11 as shown in FIG. 4. The energy storage unit 1E is to contribute power to the auxiliary devices 2.sub.aux when their peak power consumption exceeds the power produced by the standby power supply 1S. A monitoring unit 10 can keep a wind turbine controller (WTC) informed of the total capacity of the auxiliary power supply arrangement 1, so that the WTC canif necessaryissue commands to reduce power consumption of one or more auxiliary devices 2.sub.aux in order to ensure that the wind turbine 2 can remain operational until it is once again connected to the grid. The monitoring unit 10 can be part of the auxiliary power supply arrangement 1.

[0041] The standby power supply 1S and the energy storage unit 1E can be connected in series as shown in FIG. 5. Alternatively, the standby power supply 1S and the energy storage unit 1E can be connected in parallel as shown in FIG. 6.

[0042] During an on-grid mode M.sub.ongrid operation of the wind turbine, power is supplied to the auxiliary devices 2.sub.aux by the wind turbine itself or by the grid as shown in FIG. 7. The diagram indicates a fluctuating power demand 70. The demand of the auxiliary devices 2.sub.aux is regularly below an average or steady-state level P.sub.stst. Occasionally, the auxiliary devices 2.sub.aux draw a high current as indicated by the brief transients or peaks 70.sub.trans, for example resulting from high inrush currents drawn by a yaw motor or pitch motor upon startup. During the on-grid mode M.sub.ongrid, the power peaks 70.sub.trans are easily covered by the essentially unlimited grid power.

[0043] However, in an off-grid mode M.sub.offgrid, power to the auxiliary devices 2.sub.aux must be supplied by the standby power supply 1S and the energy storage unit 1E. The power peaks 70.sub.trans are no longer covered by a limitless power supply, but by the comparatively small standby power supply 1S and energy storage unit 1E of FIGS. 1-4. The average or steady-state power P.sub.stst is covered by the standby power supply 1S. When auxiliary devices draw a high current, the standby power supply 1S is not required to cover the power peak, and instead the deficit P is made up by the energy storage unit 1E, which discharges power as required during the peak 70.sub.trans until power consumption is once again at or below the power level P.sub.stst delivered by the standby power supply. Whenever power consumption is below that power level P.sub.stst, the energy storage unit 1E may be recharged from the standby power supply 1S, as necessary.

[0044] FIG. 8 shows a wind turbine 8 with a prior art standby power supply 8S. The specification of the standby power supply 8S is based on the peak power consumption that must be covered when an auxiliary device 8.sub.aux draws a high inrush current for a brief period as explained above.

[0045] FIG. 9 illustrates the management of prior art auxiliary power for the wind turbine of FIG. 8. When the wind turbine 8 is operated in an off-grid mode M.sub.offgrid, power to the auxiliary devices must be supplied by the standby power supply 8S. The diagram indicates a fluctuating power demand 90. Here also, while the demand of the auxiliary devices 8.sub.aux is regularly below an average level P.sub.stst, an auxiliary device may occasionally draw a high current as indicated by the peaks 90.sub.trans. Any such peak demand must be covered by the standby power supply 8S alone, so that the capacity of the standby power supply 8S must be accordingly large, for example in the order of 150 kVA-400 kVA.

[0046] FIG. 10 shows a further embodiment of the invention, in which the inventive auxiliary power supply arrangement 1 is configured to supply power to multiple wind turbines 2. A scaled-up standby power supply 1S may be provided at a wind park substation to provide standby power to all auxiliaries 2aux of all wind turbines 2 in the event of a grid outage. Such an auxiliary power supply arrangement 1 can provide standby power to the wind turbines 2 over a suitable network of power cables connecting the wind turbines of the wind park. Of course, the standby power supply 1S can comprise any number of units that collectively cover the average power requirements of the auxiliary devices of the wind turbines 2. The energy storage arrangement can comprise any number of energy storage units 1E, for example an energy storage unit 1E local to each wind turbine 2 as shown here, to cover transient power requirements of the auxiliary devices 2aux as explained above.

[0047] Although the invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0048] 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. The mention of a unit or a module does not preclude the use of more than one unit or module.