Title of Invention

WIND ENERGY PLANT WITH A ROTER BLADE ADJUSTING MECHANISM

Abstract

Wind energy plant (10) with a rotor (12) that has at least one angularly adjustable rotor blade (14) and a generator for generating electrical power that is directly or indirectly coupled with the rotor (12). It is directly or indirectly coupled with a supply network (25) for the feeding of electrical power. It has is directly or indirectly coupled with a supply network (25). It has rotor blade adjusting mechanism for adjusting the angle of the rotor blade (14), consisting of at least one blade adjusting drive (20) with at least one D.C. motor (23) that is coupled with the electrical supply network (25) through an inverter (24), a control unit (33) coupled with the inverter (24) through which the control or regulation of the blade adjusting drive (20) takes place, and a D.C. voltage source (31) that ensures energy supply to the blade adjusting drive (20) in case of interruption in power supply (25). The D.C. voltage source (31) is alternatively coupled directly with the blade adjusting drive (20) or indirectly with the adjusting drive (20) through the inverter (24), whereby in case the D.C. voltage source (31) is coupled indirectly with the blade adjusting drive (20) through the inverter (24), and the invertor (24) alternatively converts the A.C. voltage coming from the main power supply (25) or the D.C. voltage coming from the D.C. voltage source (31).

Full Text

WIND ENERGY PLANT WITH A ROTOR BLADE ADJUSTING MECHANISM This invention relates to a wind energy plant with a rotor. Known wind energy plants generally have a rotor with three rotor blades, whereby the rotor for generating an eleetrical power is eoupled directly or indirectly with a generator. The generator could further be coupled with an electrical mains power supply for feeding the generated electrical power. In generic wind energy plants the rotor blades are designed in such a way that they can be angularly adjusted. In this way. the alignment of the rotor blades could be adjusted for strong wind force in such a way, that the energy consumption from the wind can be reduced. For adjustment of the rotor blades the generic wind energy plants are designed in such a way, that at least one blade adjustment mechanism is foreseen for all three rotor blades. Known wind energy plants are designed in such a way, that a rotor blade adjusting mechanism is foreseen for each rotor blade, whereby the rotor blade adjusting mechanism, among other things, has a blade adjusting drive with a D.C. motor that is connected to the electrical power supply through an inverter. Generally the high rotation speed of the drive motor is transmitted through a high step-up gear to a slowly rotating driving pinion that mates with a ring gear connected directly to the rotor blade. The rotor blade adjusting mechanism further has a control unit that regulates the blade adjusting drive. On safety grounds, and for protecting wind energy plant, it has to be ensured that the wind energy plant can be shut down at any time or in case of any operational problems. As a rule, known wind energy plants are shut down by rotating the rotor blades into the so-called flag position. By flag position one means turning out the rotor blades from the wind, so that, like in the case of a flag, only a minimum acting surface is offered to the wind and thus the required energy for maintaining the rotation movement of the blade can no longer be taken up from the wind and. as a result the plant stops or is at least brought to a very slow rotation movement. One operational problem could be, for example, a power cut from the main supply. In such a case, the power supplier could instruct, that for protecting the electrical power supply, the wind energy plant has to be cut off from the electrical mains within a defined time span. By cutting off the wind energy plant from the power supply, the generated power can no longer be fed into the network, which could very quickly lead to critical conditions of over-speed in rotation. Therefore, for the sake of its own protection in case of power cuts, it should be possible to shut down the plant. A cut in power supply however also has the consequence, that even the electrical blade adjusting drive is no longer supplied with energy from the mains and the wind energy plant can no longer be shut down by adjusting the rotor blades. In order to nevertheless ensure shutting down of wind energy plants by rotating the rotor blades into flag position, an additional D.C. voltage source is provided in the rotor blade adjusting mechanism of known wind energy plants, which in case of power cuts, gets directly connected to the blade adjusting drive, so that power supply to the blade adjusting drive is ensured at all times. However, the disadvantage of these known wind energy plant is, that on account of direct coupling of the D.C. voltage source with the blade adjusting drive, it is only possible to rotate the rotor blades in an unregulated manner, generally in the direction of the flag position. Regulation to a precise setting of a desired rotor blades angle, or especially a rotor blade adju.sting velocity, is not possible in case of operational problems, with the help of generic wind energy plants. This means that in case of interruption of power supply, the rotor blades of a wind energy plant are always forcibly rotated into the braking or flag position and the plant is generally shut down abruptly. An abrupt standstill of a plant however also implies the coming into play of loads that have to be taken into account while dimensioning the plant, and thus essentially lead to higher plant costs. Forced shutting down of the plant also always means additional economic losses for the operator. These losses are especially annoying if, for example, the interruption in power supply is for a very short duration, as shutting down and starting of the plant generally takes a much longer times than the duration of the power cut. It is the task of this invention to extend a known wind energy plant in such a way, that an optimum regulation of the rotor blade angle is possible in normal operation, but also especially in case of various operational problems, e.g. in case of a power cut. The various aspects of this task are fulfilled with the help of the wind energy plant as described hereunder. The wind energy plant has a rotor with at least one angle-adjustable rotor blade. It further comprises of a generator for generation of electrical power that can be directly or indirectly coupled with the rotor, and for feeding the electrical power, can be coupled directly or indirectly with an electrical supply network, as well as at least one rotor blade adjusting mechanism for adjusting the angle of the rotor blade, whereby in case of several rotor blades - generally there are three blades per wind energy plant - a rotor blade adjusting mechanism can be provided with each rotor blade. The rotor blade adjusting mechanism consists of, among other things, at least one blade adjusting drive with at least one D.C. motor that can be coupled with the electric supply network through an inverter, a control unit coupled with the converter by which the control and/or regulation of the blade adjusting drive takes place, and a D.C. voltage source that ensures energy supply to the blade adjusting drive in case of an interruption of power supply. It is pointed out that no distinction is made between control and regulation here below, as with the help of this invention a control as well as a regulation of the rotor blade adjusting mechanism is possible. The expression 'control unit' therefore always also includes the possibility of regulation of the blade angle. According to the invention it is foreseen that the D.C. voltage source can be coupled with the plate adjusting drive either directly or even indirectly through the inverter, whereby the D.C. voltage source is preferably coupled indirectly with the plate adjusting drive through the inverter, and the inverter is designed in such a way. that it is in a position to convert A.C. voltage coming from the mains supply as well as also the D.C. voltage coming from the D.C. voltage source. fhe wind energy plant according to this invention offers the advantage, that the plate adjusting drive can be regulated even in case of interruption in the power supply, by means of the control unit. In case of interruption of power supply and the thereby warranted necessity of shutting down the plant, the rotor blade is no longer rotated immediately or in an unregulated manner into the flag position, but there exists the possibility that the rotor blade is rotated into the flag position slowly with a pre-givcn regulation speed. This offers the advantage that the plant does not come to a standstill abruptly but can be shut down smoothly. Like before, the possible alternative of directly coupling the D.C. voltage source with the blade adjusting drive offers the advantage, that in case of failure of the inverter, on safety grounds and for protecting the plant, it can be ensured that the wind energy plant can be shut down by rotating the rotor blades into the flag position. It is known from wind energy plants whose blade adjusting drive has an A.C. motor instead of a D.C. motor, that the D.C. voltage source is coupled directly with the inverter. However, the disadvantage of these not-generic wind energy plants is. that in case the inverter fails to function, e.g. due to a lightning strike, simultaneously the rotor blade adjusting mechanism also fails and therefore there is no possibility of shutting down the wind energy plant in case of an emergency. Therefore, use of a D.C. motor in the blade adjusting drive should be considered as particularly advantageous, as the D.C. motor can be coupled with the D.C. voltage source directly even in case the inverter fails to function, and thus it is ensured that the rotor blades can be rotated to the flag position in any case, in order to shut down wind energy plant. As already mentioned above, the wind energy plant in the state-of-the-art technology can be shut down in case of interruption in power supply only by forcibly rotating the rotor blades to the flag position, The forced rotation of the rotor blades however leads to the fact, that the plant is shut down relatively abrupfly, which can generate very high loads in the plant. On account of the possibility of shutting down the wind energy plant according to the invention in a regulated manner, these high loads can also be reduced, so that this does not have to be taken into account in the dimensioning of the plant to that extent, and the plant can be manufactured in a cost-effective and advantageous manner. Besides, a synchronous run of the rotor blades can be ensured while rotating to the flag position by means of the super-ordinate control unit, fhis means that the rotor blades can be rotated synchronously into the Hag position, by which lower loads can be attained in the plant. This invention further offers the advantage, that the plant does not have to be forcibly shut down in case of interruption in power supply, but there exists the possibility in case of interruption in power supply to keep the rotation speed of the wind energy plant as per the invention constant over a defined time span by means of the also regulate-able rotor blade angle, or to regulate it in a different manner as desired. Thus operation of the plant can be maintained in case of interruption in power supply for a short period of time, whereby the economical losses, that would otherwise have been incurred in case of a sudden standstill of the plant, gets reduced. In an advantageous extension of the invention, the regulation of the rotor blade adjustment of a wind energy plant as per the invention can take place by means of an operational fault mode, in case of interruption in power supply, with the help of the control unit. The operational fault mode can be stored in the plant. However, there is also the possibility that the mode is generated in the control unit only on occurrence of an operational fault, or the operational fault mode can be fed to the control unit by an operations computer that regulates the entire operations of the plant or the entire wind park. Through the operational fault mode one can determine how the regulation of the blade adjustment should be in case of an operational fault. The operational fault mode can be programmed in such a way that it is in a position to distinguish between the different operational faults and carry out regulation measures accordingly. For example, it could be stored in the operational fault mode, that in case of interruption of power supply in one or more phases, the rotation speed of the rotor can be kept constant over a defined time span and the wind energy plant is shut down only after expiry of the time span, if the interruption in power supply continues. In the operational fault mode it can also be stored, that in case the inverter fails, the battery/batteries can get directly connected to the blade adjusting drive. Furthermore, it can also be stored in the operational fault mode, as to how to effect a manual emergency- off, as in that case the plant has to be connected voltage-free to a great extent, in order to increase the safety of personnel. In the operational fault mode, it can also be stored that the plant is brought to a standstill as quickly as possible, but while also protecting the plant as far as possible, with the help of a regulated blade adjusting velocity. In yet another extension, the wind energy plant as per the invention offers the advantage, that in case of a standstill of a wind energy plant and simultaneous absence of power supply, the blade adjusting drive can be controlled by indirect coupling with the D.C. voltage source by means of a control unit, for starting the plant, whereby the absence of power supply could mean a power cut or even an intended switching-offof the power supply. In a liirther advantageous extension, it is foreseen that the D.C. voltage source is a battery. A battery offers the advantage of being a constant energy feeder that is in a position provide the required energy for operating the D.C. motor. However, there is also the possibility of using the so-called ultracaps as D.C\ voltage source, whereby these are compact condensers with high energy density that are in a position to store the required energy for driving the D.C. motor. One could also think of providing a D.C. generator, which is driven with the rotation movement of the rotor, i.e. by means of its kinetic energy. For this, an active part of the generator is coupled in a rotating manner with the wind rotor (preferably with the rotor hub), while the other active part stays fixed with the machine car. As soon as the rotor rotates, a rotation speed-dependent D.C. voltage can be tapped at the generator clamps, which can be directly applied to the blade adjusting drive or to the intermediate inverter circuit after conversion, if required (e.g. step-up device). For energy supply, the D.C. motor of the blade adjusting drive is connected during normal operation through a converter to the A.C. power supply of the power supplier, whereby the inverter converts the A.C. energy provided from the main supply into a DC. energy. According to this invention, the inverter is further in a position to convert a fed D.C. voltage energy in such a way, that the D.C. motor can be operated in a regulated manner through the inverter. According to an advantageous extension of the invention, the inverter can be designed in such a way that it has a rectifier, by means of which the A.C. voltage fed from the mains is converted into a pulsating D.C. voltage, as well as an intermediate D.C. voltage circuit that has the task of stabilizing the voltage between the rectifier and the D.C. motor. I he D.C. voltage intermediate circuit mainly serves as buffer for compensating transient load demands (voltage surges). However, as a D.C. energy with variable current and voltage values is required for regulated operation of the D.C. motor, the inverter additionally has a D.C. current provider with active switches, where the active switches can be operated through the control unit. By suitable control of the active switches, the energy in the intermediate circuit can be converted into an adjustable D.C. current energy that is designed in such a way, that the D.C. motor rotates the rotor blade with a desired adjusting velocity to the desired angular position. According to a further advantageous extension, the active switch in the D.C. current provider can be an IGBT-power transistor, IGBT-power transistors have the great advantage that they can be switched on and off as required. This advantage creates the possibility of operating the D.C. motor in a regulated manner through the inverter, irrespective of whether the inverter is coupled with the electrical power supply or with the D.C. voltage source. In a further advantageous extension of the invention, it is foreseen that the coupling of the D.C. voltage source with the inverter takes place through the D.C. voltage intermediate circuit. The coupling can take place through diodes; in that case, the voltage difference between the D.C. voltage source and the D.C. voltage intermediate circuit should be accordingly adjusted, in order to avoid loads on individual components. This extension offers the advantage that the D.C. voltage source, on the one hand, supports the D.C. voltage intermediate circuit in case of interruption of power supply; on the other hand, in this way, the required energy for regulated operation of the D.C. motor despite interruption in power supply, is made available in the converter. According to another extension, it is foreseen that the rotor blade adjusting mechanism has an angle transmitter that determines the actual angle of the rotor blade and conveys the determined actual value to the control unit. 1 his offers the advantage that the control unit, or an operations computer coupled to the control unit, can determine a rotor blade angle on the basis of the determined value, even taking other plant parameter into account; this angle allows an optimum operation and hence an optimum energy utilisation. Provision of the angle transmitter further offers the possibility of controlling and, if required, correcting the prescribed angle by means of the control unit. The measures described so far relate to the solution of operational faults that could occur in case of electrical power supply to the rotor blade adjusting mechanism. The objective is to enable a regulated adjustment of the rotor blade, e.g. in case of interruption in power supply. This addresses an important problem that could occur in the operation of the wind energy plant. However, devices/mechanisms for rotor blade adjustment are relatively complex, fhere could also be other feults/disturbances that could impair the regulated adjustment of the rotor blade, so that basically there is always the need for optimisation. Another approach to the solution is described below, in which the regulated adjustment of the rotor blade is optimised and ensured, particularly in case of some other fault that is not related to the electrical system. Both approaches to the solution discussed within the scope of the invention, separately or even combined, allow that the plant can be controlled and/or regulated in an optimum manner and can remain operational even when various operational faults occur, fhe main objective of designing a wind energy plant in such a way, that the occurrence of operational faults gets compensated and the plant has to be shut down only in case of mainly major operational faults, is thus achieved in a simple manner. According to another approach to the solution, it is foreseen that the rotor blade adjusting mechanism has at least two angle transmitters, whereby the control unit is designed in such a way, that if one angle transmitter fails, then one can switch over to the other angle transmitter. In an advantageous extension of the invention, the first angle transmitter can be arranged on the motor shaft of the D.C. motor of the blade adjusting drive, whereby the motor shaft forms the drive side or so-called "fasf side (on account of higher revolution speed) of the rotor blade adjusting drive. Ideally, the second angle transmitter is provided directly on the rotor blade axis or on a pinion mating with the gear of the blade bearing. This means that the second angle transmitter is arranged on the so-called drive blade side or rotor blade side or "slow" side of the rotor blade adjusting mechanism. Provision of at least one more angle transmitter offers the advantage that the measured blade angles can be compared with one another and thus, in case of great fluctuation in the measured values, an eventual defect of a sensor or failure (breaking) of the blade drive can be detected. In such a case, the control unit can then switch over to the second angle transmitter to ensure that the actual blade angle can be determined at any point of time. It is particularly advantageous if both the approaches to the solution are combmed. In this way. one can attain a highly safe and optimally regulated plant, even for a normal operation. However, the last described solution can also be realized separately, i.e. not only in a claimed wind energy plant that has a rotor blade adjusting mechanism with a D.C. drive. Use of one or more angle transmitters can also be realized easily in other rotor blade adjusting mechanisms that, for example, have an A.C. drive. Further features, aspects and advantages of this invention are partly revealed by the following description and partly recommended by the description, or manifest themselves in the practical application of the invention. A design form of the invention is described in details below. It is obvious that other design forms can also be used and changes can be made without moving away from the scope of the invention. Brief description of the accompanying drawings: Fig. 1 shows a wind energy plant in frontal view; Fig. 2 shows a rotor blade adjusting mechanism in schematic depiction. Fig. 1 shows a wind energy plant 10 with a tower 11, on the upper end of which a rotor 12 is arranged. The rotor 12 consists of a rotor hub 13 and three rotor blades 14 that are arranged on the hub 13. The rotor blades 14 are connected with the rotor hub 13 in a rotate-able manner and for adjusting the energy consumption of the rotor 2 from the wind, can be individually adjusted around their longitudinal axis. The connection of the rotor blade 14 with the rotor hub 13 is done through bearings, e.g. four-point contact bearings or ball bearings, whereby the bearing components on to which the rotor blade is fixed, has an internal gear. Adjustment of the rotor blades 14 takes place through a rotor blade adjusting mechanism (not shown in details) with a blade adjusting drive, whereby the blade adjusting drive has a driving pinion that is arranged in such a way that it mates with the internal gear of the bearing. The blade adjusting drive further has a drive motor that is coupled with the drive pinion through a gear, so that the drive pinion can be brought into rotation movement through the drive motor. As the drive pinion mates with the internal gear of the bearing components, on to which the rotor blade is fixed, the rotor blade can thus be adjusted with the help of the drive motor. Fig. 2 schematically shows a rotor blade adjusting mechanism with a blade adjusting drive 20. The shown blade adjusting drive 20 has a driving pinion 21, a gear 22 and a drive motor 23, whereby in the shown design example, it is a D.C. motor. The D.C. motor 23 can be coupled with an electric supply network 25 through an inverter 24, whereby the electric supply network 25 supplies a three-phase A.C. current energy. Additional switching elements 26 are foreseen between the inverter 24 and the electric supply network 25, whereby one gets the possibility of cutting off the inverter 24 and thus the rotor blade adjusting mechanism from the electric supply network 25. rhe inverter 24 has the task of converting the A.C. current energy supplied by the electric supply network into a D.C. current energy that would allow operation of the D.C. motor. For this purpose, the inverter 24 consists of a rectifier 27, a D.C. voltage intermediate circuit 28 and a D.C. provider 30. The rectifier 27 has active switches, whereby in the shown example, these are IGBT- power transistors that can be switched on and off through a control unit 33, whereby a control unit 33 is coupled with an operations computer 34 that monitors and regulates the entire operation of the wind energy plant. The installation of the active switches offers the advantage, that the A.C. energy fed from the electric power supply 25 is modified by the control unit 33, using the pulse phase modulation method by appropriately switching the active switches on and off. so that a D.C. energy with pre-determined parameters gets generated, that drives the D.C. motor 23 in a specific manner for adjusting the rotor blade to a pre-given position. In case of interruption in electric power supply 25, or in case the electric power supply 25 has been shut off intentionally by opening the switching elements 26 of the wind energy plant 10, there results a coupling of the D.C. motor 23 with a battery 31, so that an energy supply to the D.C. motor is ensured. Coupling of the battery 31 with the D.C. motor 23 can take place in two ways: On the one hand, the D.C. motor 23 can be directly connected to the battery 31 through a switching element 35. Additionally, the battery 31 can however also be coupled indirectly with the D.C. motor 23 through the inverter 24. f'or this, a switchover olthc switching elements 35 takes place, whereby the D.C. motor 23 gets coupled with the inverter 24. At the same time, by closing a switch 36 the D.C. voltage intermediate circuit 28 gets coupled with the battery 31, whereby the energy supply to the D.C. motor 23 is maintained through the inverter 24. The indirect coupling of the battery 31 offers the advantage that the D.C. energy provided by the battery 31 can be modified with the help of the inverter 24 in such a way, that the D.C. motor 23 can be operated in a regulated manner and thus also a regulated blade adjustment is possible. The direct coupling of the battery 31 with the D.C. motor 23 allows only the unregulated rotation of the rotor blade, e.g. out of the wind to a so-called flag position, whereby the wind energy plant gets forcibly shut down. The direct coupling comes into application only if a rotor blade adjustment is no longer possible through the inverter 24. e.g. when the inverter 24 is no longer functional. The direct coupling of the battery 31 with the D.C. motor 24 is foreseen only on account of safety-related reasons, mainly to ensure that in case of failure of the inverter, it is still possible to shut down the wind energy plant by rotating the rotor blades to the flag position. Nevertheless the switching element 35 is preferably designed in such a way, that in powerless condition the indirect coupling of the battery 31 on to the D.C. motor 23 is activated. By means of this so-called failsafe arrangement, even in case of a lightning strike that might destroy the mains power supply and also the inverter, a safe shut down of the machine is ensured. Fig. 2 further shows schematically a first angle transmitter 37 and a second angle transmitter 38, whereby the first angle transmitter 37 is arranged in the motor shaft of the D.C. motor of the blade adjusting drive and the second angle transmitter 38 is designed as pinion that mates with a ring gear arranged on the blade root (not shown). WE CLAIM: 1. Wind energy plant (10) with a rotor (12) that has at least one angularly adjustable rotor blade (14), a generator for generating electrical power that is directly or indirectly coupled with the rotor (12) and, for the feeding of electrical power is directly or indirectly coupled with a supply network (25), at least one rotor blade adjusting mechanism for adjusting the angle of the rotor blade (14), consisting of at least one blade adjusting drive (20) with at least one D.C. motor (23) that is coupled with the electrical supply network (25) through an inverter (24), a control unit (33) coupled with the inverter (24) through which the control or regulation of the blade adjusting drive (20) takes place, and a D.C. voltage source (31) that ensures energy supply to the blade adjusting drive (20) in case of interruption in power supply (25), characterized in that the D.C. voltage source (31) is alternatively coupled directly with the blade adjusting drive (20) or indirectly with the adjusting drive (20) through the inverter (24), whereby in case the D.C. voltage source (31) is coupled indirectly with the blade adjusting drive (20) through the inverter (24), and the inverter (24) alternatively converts the A.C. voltage coming from the main power supply (25) or the D.C. voltage coming from the D.C. voltage source (31). 2. Wind energy plant (10) as claimed in claim 1, wherein a direct coupling of D.C. voltage source (31) with the blade adjusting drive (20) takes place only if the inverter (24) fails. 3. Wind energy plant (10) as claimed in claim 1, wherein in the case of indirect coupling of the D.C. voltage source (31) with the blade adjusting drive (20), the blade adjusting drive (20) is controlled through a control unit (30) with the help of an operation fault mode that is stored in the control unit (33), or generated in the control unit (33) or is fed to the control unit 33. 4. Wind energy plant (10) as claimed in claim 1, wherein in case of a standstill of the plant (10) and simultaneous failure of the electrical supply network (25) and indirect coupling of the D.C. voltage source (31) with the blade adjusting drive (20), the blade adjusting drive (20) is controlled through the control unit (33) for starting the plant (10). 5. Wind energy plant (10) as claimed in claim 1, wherein the D.C. voltage source (31) is a battery. 6. Wind energy plant (10) as claimed in claim 1, wherein the inverter (24) has a rectifier (27), a D.C. voltage intermediate circuit (28) and a D.C. provider with at least one active switch. 7. Wind energy plant (10) as claimed in the previous claim, wherein the active switch is an IGBT. 8. Wind energy plant (10) as claimed in one of the previous claims, wherein the D.C. voltage source (31) is alternatively coupled with the D.C. voltage Intermediate circuit (28). 9. Wind energy plant (10) as claimed in claim 1, wherein the rotor blade adjusting mechanism has at least one angle transmitter (37, 38) that determines the actual angle of the rotor blade (14) and conveys it to the control unit (33). 10. Wind energy plant (10) as claimed in claim 1, wherein the rotor blade adjusting mechanism has at least two angle transmitters (37, 38), whereby the control unit (33) operates such a way, that in case one angle transmitter (37, 38) fails, it switches over to the other angle transmitter (37, 38). 11. Wind energy plant (10) as claimed in the previous claim, wherein the blade adjusting drive (20) has a drive-on side and a drive-off or rotor blade side, whereby one of the angle transmitters (37, 38) is arranged on the drive side and the other one is arranged on the drive-off or rotor blade side of the blade adjusting drive (20). Wind energy plant (10) with a rotor (12) that has at least one angularly adjustable rotor blade (14) and a generator for generating electrical power that is directly or indirectly coupled with the rotor (12). It is directly or indirectly coupled with a supply network (25) for the feeding of electrical power. It has is directly or indirectly coupled with a supply network (25). It has rotor blade adjusting mechanism for adjusting the angle of the rotor blade (14), consisting of at least one blade adjusting drive (20) with at least one D.C. motor (23) that is coupled with the electrical supply network (25) through an inverter (24), a control unit (33) coupled with the inverter (24) through which the control or regulation of the blade adjusting drive (20) takes place, and a D.C. voltage source (31) that ensures energy supply to the blade adjusting drive (20) in case of interruption in power supply (25). The D.C. voltage source (31) is alternatively coupled directly with the blade adjusting drive (20) or indirectly with the adjusting drive (20) through the inverter (24), whereby in case the D.C. voltage source (31) is coupled indirectly with the blade adjusting drive (20) through the inverter (24), and the invertor (24) alternatively converts the A.C. voltage coming from the main power supply (25) or the D.C. voltage coming from the D.C. voltage source (31).

Documents:

00226-kolnp-2006-abstract.pdf

00226-kolnp-2006-claims.pdf

00226-kolnp-2006-description complete.pdf

00226-kolnp-2006-drawings.pdf

00226-kolnp-2006-form 1.pdf

00226-kolnp-2006-form 2.pdf

00226-kolnp-2006-form 3.pdf

00226-kolnp-2006-form 5.pdf

00226-kolnp-2006-international publication.pdf

00226-kolnp-2006-international search authority.pdf

226-KOLNP-2006-FORM 27.pdf

226-KOLNP-2006-FORM-27.pdf

226-kolnp-2006-granted-abstract.pdf

226-kolnp-2006-granted-claims.pdf

226-kolnp-2006-granted-correspondence.pdf

226-kolnp-2006-granted-description (complete).pdf

226-kolnp-2006-granted-drawings.pdf

226-kolnp-2006-granted-examination report.pdf

226-kolnp-2006-granted-form 1.pdf

226-kolnp-2006-granted-form 18.pdf

226-kolnp-2006-granted-form 2.pdf

226-kolnp-2006-granted-form 26.pdf

226-kolnp-2006-granted-form 3.pdf

226-kolnp-2006-granted-form 5.pdf

226-kolnp-2006-granted-reply to examination report.pdf

226-kolnp-2006-granted-specification.pdf

226-kolnp-2006-granted-translated copy of priority document.pdf

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