DE102010019444A1 - rotor blade - Google Patents

Abstract

Disclosed is a rotor blade adjustment device of a wind power plant with a speed and directional variable motor-pump unit which is fluidly connected to a hydraulic actuator via a hydraulic control / regulation system. The actuator is mechanically coupled to at least one rotor blade of the wind power plant for its rotation about its longitudinal axis. According to the invention, an electrical control circuit comprising an emergency power supply device is provided for operating the motor.

Description

The present invention relates to a rotor blade adjusting device of a wind turbine according to the preamble of patent claim 1.

A wind turbine rotates by the buoyancy of the wind on the rotor blades, the wind power increases with the cube of the wind speed. This means for modern wind turbines that usually from a wind speed of about 9 m / s rotor power (generated by the buoyancy force) is greater than the rated power, so that the wind turbine must be limited in their output power to material damage especially to the sensitive Rotor blades to avoid.

Basically, there are two main concepts of power limitation in the prior art:
One possibility is basically to limit the power output by a specifically initiated stall on the rotor blades when exceeding a certain wind speed. This so-called stall control is the simplest and also the oldest control system and is based on designing the rotor blade profile (ie its bulge) so that at a certain analytically determinable wind speed (at constant speed) turbulences occur on the rotor blade, whereby the buoyancy is automatically reduced and so that the performance of the plant can be maintained at rated power. The problem of this type of control, however, is that the rotor blade profile does not remain the same but changes in the course of the operating time due to weather conditions such as rain, ice / snow, wear, etc. The stall wind speed can therefore not be determined exactly in advance, so that the design of the rotor blade profile is difficult. For this reason, stall limits are set so that the rated power is not reached to provide a safety buffer, which, however, degrades the power yield and hence the efficiency of the plant.

• – Bei einem sehr schwachen Wind (0–4 m/s) produziert eine herkömmliche Windkraftanlage nicht, da die Anströmgeschwindigkeit des Winds zu gering ist, um eine ausreichende Auftriebskraft am Rotorblatt zu erzeugen. In diesem Fall werden die Rotorblätter in eine sogenannte Fahnenstellung (Pitchwinkel = 90°; Anströmwinkel = 0°) gedreht, in der kein Auftrieb erzeugt wird.
• – Bei leichtem Wind (4–13 m/s) dreht die Windkraftanlage und produziert nutzbare Leistung, wobei jedoch der Wind zu schwach ist, um die Nennleistung der Anlage zu erreichen. In diesem Fall wird der Pitchwinkel minimal (Pitchwinkel = 0°) und damit der Anstellwinkel maximal, um so viel wie möglich an Windenergie in mechanische Energie umzuwandeln.
• – Bei Starkwind (13–25 m/s) kann die Nennleistung der Anlage überschritten werden. Um dies zu verhindern ist die Anlage dann „gepitcht”, d. h. die Rotorblätter werden kontinuierlich oder stufenweise zurück in Richtung Fahnenstellung gedreht.
• – Bei Sturm (ab 25 m/s) ist das Beschädigungsrisiko zu hoch, sodass aus Sicherheitsgründen dann die Rotorblätter grundsätzlich in Fahnenstellung verdreht werden.

Another possibility of the power restriction concerns the (active) rotation of the rotor blades (pitch), according to which the regulation of the power in pitch-controlled wind turbines is ensured by the rotation of the rotor blades by means of the so-called pitch system. Here, the following flow-mechanical relationships are used:
In the usual operating range of wind turbines, the power coefficient of a rotor blade increases with the angle of attack (comparable to the wing of an aircraft). This means that a low angle of attack provides a low buoyancy force and consequently a lower power. With this principle, the power is now adapted by twisting (pitching) the rotor blades to the wind speed.

• - In a very weak wind (0-4 m / s) produces a conventional wind turbine not, since the flow velocity of the wind is too low to produce a sufficient buoyancy force on the rotor blade. In this case, the rotor blades are rotated in a so-called plume position (pitch angle = 90 °, angle of attack = 0 °), in which no lift is generated.
• - In light wind (4-13 m / s), the wind turbine turns and produces usable power, but the wind is too weak to reach the rated output of the system. In this case, the pitch angle becomes minimum (pitch angle = 0 °) and thus the pitch angle maximum, to convert as much as possible of wind energy into mechanical energy.
• - In case of strong wind (13-25 m / s), the nominal capacity of the system can be exceeded. To prevent this, the system is then "pitched", ie the rotor blades are rotated continuously or stepwise back towards the flag position.
• - In the event of a storm (from 25 m / s), the risk of damage is too high so that, for safety reasons, the rotor blades are always turned into the feathered position.

It has been found that even with a conventional wind rotor, which generally has three rotor blades, it is sufficient to pitch only one rotor blade in order to adapt the system to changing wind speeds. Incidentally, this mode of operation according to the above explanation also applies to the subject matter of the invention.

From the prior art, for example according to the WO 2009/064 264 a pitch system of this type is known, consisting of an electro-hydraulic actuator for controlling / regulating the rotational position of a rotor blade of a wind turbine. The actuator has a function of the electric current and polarity speed and direction variable electric motor which drives a hydraulic pump via a motor shaft as the primary pressure medium source. The pump thereby delivers a hydraulic fluid via a hydraulic circuit to a hydraulic motor, for example in the form of an actuating cylinder, which is arranged (together with the pump and the electric motor) within a rotor hub and operatively connected to a rotor blade for its rotation about the longitudinal axis. In the hydraulic circuit, a further, secondary pressure medium source is integrated in the form of a pressure accumulator, which feeds a pressurized hydraulic fluid into the hydraulic circuit in the event of failure of the primary pressure medium source, so as to rotate the rotor blade in its (safe) flag position as defined above in the context of emergency running ,

Furthermore, the EP 1 739 807 A2 an electric actuator for a rotation of at least one rotor blade of a wind turbine with an emergency power supply device which is connected to an electrical circuit of the actuator. In this case, the emergency power supply device comprises an energy store which provides a backup voltage which in the present case is less than 80% of the rated operating voltage of the electrical circuit and can then be switched on when the circuit voltage drops below this backup voltage.

The object of the invention is to provide a rotor blade adjustment of a wind turbine, which allows a simplified kinematics, taking advantage of the advantages of an electric and hydraulic Blattverstellsystems.

This object is achieved by a rotor blade adjusting a wind turbine with the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

To solve the problem, a rotor blade adjusting a wind turbine is therefore proposed with a direction variable and preferably variable-speed motor-pump unit, which is fluidly connected via a hydraulic control / regulation with a hydraulic actuator, with at least one rotor blade of the wind turbine for its rotation about its Longitudinal axis is mechanically coupled. According to one aspect of the invention, the electrical control circuit of the motor-pump unit is equipped with an emergency power supply device that supplies at least the control circuit with electrical energy in case of failure of an external power grid. In this way, all the functions of the hydraulic control, including the intermediate, electromagnetically actuated valves, at least for the emergency operation can be maintained. The hydraulic control therefore does not necessarily have to be designed for an (electrically de-energized) emergency operation.

It is advantageous to design the emergency energy supply device as an accumulator or capacitors which can be connected to it at a predetermined voltage drop in the electrical control circuit. Such accumulators are now very durable and even with small dimensions have a high energy density, which is sufficient to run an emergency.

According to another aspect, it is provided that the emergency power supply device for supplying power to the electrical control circuit and the motor-pump unit is switchable. If, therefore, the power supply to the motor is interrupted, it can be maintained at least for emergency operation via the emergency power supply device.

Another aspect of the invention relates to the hydraulic control / regulation, which according to the invention has a hydraulic emergency operation device for supplying the hydraulic actuator with hydraulic pressure energy in case of failure or reduced power of the motor-pump unit. Namely, should the electric drive motor of the hydraulic pump have a fault, the electric emergency power supply would be ineffective. In this case, an auxiliary hydraulic pressure can be ensured at least for emergency running (for rotation of the at least one rotor blade into the feathering position). This dual security has significant advantages over the prior art. The exclusively electrical protection has, as already indicated, no effect in the event that, for example, the electric motor has a malfunction as the last link in the electrical control chain. The hydraulic accumulator acts directly on the hydraulic actuator (actuator) and thus the last link in the hydraulic timing chain. However, pressure accumulators can lose the boost pressure over time. The combination of both safety systems therefore offers the greatest protection against system malfunctions.

Finally, it should be pointed to another aspect of the invention, according to which the rotor blade adjusting device is also equipped with a direction variable and preferably variable-speed motor-pump unit, which is fluidly connected via a hydraulic control / regulation with a hydraulic actuator. The actuator is mechanically connected to at least one rotor blade for its pitch adjustment. It is intended to form the actuator as a pressure cylinder of multi-chamber design (preferably three pressure chambers), wherein a pressure chamber is fluid-connected exclusively for emergency with the pressure accumulator, whereas the other pressure chambers acted upon by the pressure pump with hydraulic fluid exclusively for the normal control / control operation are. In this way, the emergency-pressure chamber with respect to the accumulator pressure and storage volume of the pressure accumulator adapted and thus the emergency operation system can be optimized without the rest of the hydraulics must be adapted accordingly. It should be noted at this point that this last-mentioned aspect of the invention can be implemented independently of or in combination with the previously enumerated aspects in a rotor blade adjusting device, and therefore can also be claimed separately from the other aspects.

The invention will be explained below with reference to preferred embodiments with reference to the accompanying drawings.

1 1 shows a block diagram relating to a rotor blade adjusting device of a wind power plant for illustrating the possible combinations of the individual components of an electric and hydrostatic drive,

2 shows a rotor blade adjusting a wind turbine according to a first preferred embodiment of the invention,

3 shows a Rotorblattverstelleinrichtung a wind turbine according to a second preferred embodiment of the invention and

4 shows a rotor blade adjusting a wind turbine according to a third preferred embodiment of the invention.

In the 1 schematically a rotor blade adjustment of a wind turbine according to the invention shown with a hydraulic system 1 , preferably consisting of a direction variable and preferably variable-speed motor-pump unit 2 that have a hydraulic control / regulation 4 with a hydraulic actuator 6 fluidly connected. The actor 6 is mechanically coupled to at least one (not shown) rotor blade of the wind turbine for the rotation about its longitudinal axis. To operate the engine 8th is an emergency power supply device according to the invention 10 comprehensive electrical control circuit 12 intended. Alternatively or in addition to this, the hydraulics 1 with an emergency operation device (emergency storage) 14 be provided. Accordingly, the rotor blade adjusting device according to the invention has at least one, preferably two safety systems, with the aid of which, in the event of a malfunction, the at least one rotor blade of the wind power plant can be rotated into the flag position as part of an emergency operation.

On the one hand is an electric emergency storage 10 provided, the electric drive (electrical control circuit 12 and possibly engine 8th , which together form an electric servo drive) supplied in the event of failure of a primary power grid with electrical energy sufficient for at least one emergency run as defined above.

On the other hand, the hydraulics can optionally also be added 1 (Pump 16 , hydraulic regulation / control 4 , Actuator 6 , which together form a hydrostatic transmission) with a hydraulic emergency accumulator 14 be equipped, that of the hydraulics 1 supplying a hydraulic energy, for example in the form of a hydraulic fluid flow. This hydraulic emergency storage 14 makes sense, for example, if the engine 8th is disturbed at the end of the electric drive chain and therefore an emergency electrical supply would be ineffective.

In the 2 shows a first embodiment of the invention is shown, in which the above-explained basic principle is technically implemented.

Accordingly, a not further illustrated rotor blade of a wind turbine by a Gleichgangzylinder 6 rotated about its longitudinal axis, which is coupled via a likewise not shown lever mechanism with the rotor blade. For actuating the cylinder 6 is a pressure pump 16 provided parallel to the cylinder 6 is switched, ie whose two connections to a respective pressure chamber 6A . 6B of the cylinder 6 connected. The pressure pump 16 can promote a hydraulic fluid in both directions, the hydraulic fluid in the pressure chambers 6A . 6B The cylinder is only ever pumped.

Parallel to the pressure pump 16 is an (inverted) shuttle valve 18 in a pressure pump bypass line 20 connected to a reservoir 22 for tracking (sucking in) hydraulic fluid via the shuttle valve 18 connected.

Furthermore, to one of the pressure chambers 6B of the cylinder 6 , which must be pressurized to rotate the rotor blade in its flag position, a secondary pressure medium source, for example in the form of a pressure accumulator 14 connected via a control valve 24 , Preferably, an electromagnetically controlled (openable) 2/2-way valve with this pressure chamber 6B is fluid-connectable. The pressure chamber 6B opposite pressure chamber 6A has an additional access 26 to the expansion tank / tank 22 where in this access 26 On-off valve 28 , Preferably, an electromagnetic opening 2/2-way valve is interposed, which is spring-biased in a blocking position.

The pressure pump is driven 16 by an electric motor 8th which in turn is controlled by an electric circuit (driving circuit), not shown, such that the direction of rotation and preferably the speed of the motor 8th is variable. The electrical circuit is equipped with an emergency power supply device in the form of a rechargeable battery, which is the electrical circuit and possibly the electric motor 8th for a certain (limited) time or a certain max. Actuating movement of the cylinder 6 can supply with emergency power.

The functioning of in 1 Rotorbladeverstelleinrichtung described can be described as follows:
In normal (trouble-free) operation, all the directional control valves are energized, so that the directional control valve 24 between accumulator 24 and pressure chamber 6B and the directional valve 28 between tank 22 and pressure chamber 6A in locked position. Thereby the pressure pump becomes 16 via the variable-speed and direction-variable electric motor 8th operated so that at least one rotor blade receives a certain pitch angle as a function of the wind force, in which the rotor power does not exceed the rated power of the system. It should be mentioned that as an alternative to the variable speed electric motor 8th also the pressure pump 16 can be performed variable displacement. To the accumulator 14 to load, must be removed from the hydraulic fluid circuit. For this purpose, the shuttle valve 18 via an external suction line with the tank 22 fluid-connected, as already described above, so that the pressure pump 16 Fluid from the tank into the accumulator 14 nachfördern until it contains a predetermined boost pressure.

When a fault occurs, ie a drop in the regular voltage / power supply of the electrical circuit and / or a decrease in the delivery rate of the pump 16 and / or reducing the hydraulic pressure in the hydraulic control 4 an emergency operation is triggered below a respective predetermined value, after which the rotor blade adjustment device is operated for an emergency operation for adjusting the rotor blade into the feathering position.

In this case, the electrical emergency power supply is applied to the electrical circuit, wherein the electrical control circuit 12 the hydraulic circuit 4 so driven that the cylinder 6 is pressurized for a rotation of the rotor blade in the flag position. Should the electric motor 8th be disturbed, ie the connection of the electrical emergency power supply device have no effect, the hydraulic emergency operation device is activated. In this case, therefore, the electric power to all directional valves 24 . 28 interrupted, so that they are switched by the corresponding spring preload in the open position. Accordingly, the pressure accumulator 14 via the upstream directional valve 24 to the hydraulic control 4 unlocked and a corresponding actuation pressure in the cylinder 6 for a rotation of the rotor blade in the flag position builds. Because the pump 16 can stand, the hydraulic fluid from the chamber 6A not over the pump 16 escape. However, the chamber has 6A in this (emergency) case via the directional control valve 28 direct access to the tank 22 so that hydraulic fluid in the emergency movement of the cylinder out of the chamber 6A in the tank 22 is pressed.

The 3 shows a second preferred embodiment of the invention, which corresponds in principle to the first embodiment described above, but dispenses with the arrangement of a hydraulic emergency device. In this case, only an electric emergency power supply device is provided to the electric motor 8th to power for operating the hydrostatic transmission. Since no pressure accumulator is provided in the second embodiment, the (pumpless) operation of the actuator 6 is also no external access with interposed 2/2-way valve between the one pressure chamber 6A of the actor 6 and the tank 22 necessary, as described in the first embodiment.

Finally, a third embodiment of the invention with reference to the 4 described, which corresponds in principle to the first embodiment of the invention, in which, however, a multi-chamber cylinder 6 , Preferably, a three-chamber cylinder is used for a rotation of the at least one rotor blade.

In this case, the accumulator is 14 for emergency operation to a single chamber 6B via the electromagnetically openable directional control valve 24 connected, which is pressurized in this case, however, exclusively for rotating the rotor blade in the feathered position in an emergency. For this purpose, the (emergency) pressure chamber 6B a pressure relief or access line 26 connected directly to the tank 22 leads and in the likewise an electromagnetically openable 2/2-way valve 28 is interposed. The directional valve 28 is energized in normal operation and thus in the open position, so that the piston during an axial movement hydraulic fluid from the (emergency) pressure chamber 6B via the access line 26 can displace or suck.

The two, the pressure chamber 6B opposite pressure chambers 6A . 6C of the multi-chamber cylinder are at the two ports of the pump 16 connected, so that the cylinder piston in dependence of the conveying direction of the pump 16 in a normal operation back and forth is movable. These two pressure chambers 6A and 6C are also connected directly via a short-circuit line in the one electromagnetically openable 2/2-way valve 30 is interposed. after all, it's up to the pump 16 the pressure pump by-pass line 20 arranged in which the (inverted) shuttle valve 18 is in between, with the tank 22 fluidly connected

With regard to the operation of the third preferred embodiment, the following is carried out:
As stated above, the pump is 16 with the chambers 6A and 6C fluidly connected to move the cylinder piston during normal operation. In regular operation, the directional control valves are 24 . 28 and 30 energized. This is the valve 28 opened and the valves 24 and 30 closed. Ie. the accumulator 14 is from the chamber 6B disconnected and there is a connection over the line 26 between the tank 22 and the chamber 6B while chambers & A and & C are separated. In the regular movement of the piston thus the corresponding volume of fluid between the two chambers 6A and 6C pumped and simultaneously between the chamber 6B and the tank 22 replaced.

In an emergency (for example, in power failure valves are no longer energized) is the memory 14 with the chamber 6B connected while the chambers 6A and 6C over the valve 30 be shorted together. The memory pressure on the chamber 6B acting pressure force pushes the piston according to the 4 to the left (in flag position). The volume of oil from the chamber 6A to the chamber 6C repressed. Possible differences in volume due to possible area ratios are achieved via the shuttle valve 18 balanced.

The advantage of such a multi-chamber cylinder consists essentially in the fact that by a suitable choice of the area ratios interconnection of the cylinder chambers and the position of the memory on a piston surface dynamic, energetic and advantages in space can occur.

LIST OF REFERENCE NUMBERS

1

hydraulic

2

Motor-pump unit

4

Hydraulic control

6

Actuator / cylinder

6A, 6B, 6C

cylinder chambers

8th

Electric engine

10

Emergency power supply device

12

Electrical control circuit

14

Emergency operation / accumulator

16

pump

18

shuttle valve

20

Pressure pump bypass line

22

tank

24

Control valve between pressure accumulator and cylinder

26

Access (managed)

28

2/2 way valve

30

Switching valve for pressure chamber 6C

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2009/064264 [0006]
• EP 1739807 A2 [0007]

Claims (9)

Rotor blade adjusting device of a wind turbine with a direction-variable motor-pump unit ( 2 ) via a hydraulic control system ( 4 ) with a hydraulic actuator ( 6 ) is fluidly connected, which is mechanically coupled to at least one rotor blade of the wind turbine for rotating about its longitudinal axis, characterized by an emergency power supply device ( 10 ) comprehensive electrical control circuit ( 12 ) of the motor-pump unit ( 2 ). Rotor blade adjusting device according to claim 1, characterized in that the emergency power supply device ( 10 ) are an accumulator or capacitors which at a predetermined voltage drop in the electrical control circuit ( 12 ) are switchable to these. Rotor blade adjusting device according to claim 2, characterized in that the emergency power supply device ( 10 ) for supplying power to the electrical control circuit ( 12 ) and the motor-pump unit ( 2 ) is provided. Rotor blade adjusting device according to claim 1 or 2, characterized by a hydraulic emergency operating device ( 14 ) for the supply of the hydraulic actuator ( 6 ) with hydraulic pressure energy in case of failure or reduced power of the motor-pump unit ( 2 ). Rotor blade adjusting device according to one of claims 1 to 4, characterized in that the hydraulic actuator ( 6 ) is a hydraulic piston-cylinder unit. Rotor blade adjusting device according to one of the preceding claims 1 to 5, characterized in that the motor-pump unit ( 2 ) through the electrical control circuit ( 12 ) Variable speed is controllable. Rotor blade adjusting device according to one of claims 1 to 6, characterized in that the hydraulic piston-cylinder unit is a multi-chamber cylinder, preferably of the three-chamber design. Rotor blade adjusting device according to claim 7, characterized in that only one of the chambers ( 6B ) for rotation of the at least one rotor blade meanwhile flag position in an emergency with hydraulic fluid from an emergency operation device ( 14 ) preferably a pressure accumulator ( 14 ) is acted upon whereas at least two other chambers ( 6A . 6C ) can be acted upon for rotation of the at least one rotor blade and in the direction of the flag position in a regular operation with hydraulic fluid. Rotor blade adjusting device according to claim 8, characterized in that only one chamber ( 6B ) the hydraulic emergency operation device ( 14 ) via a control valve, preferably an electromagnetically openable 2/2-way valve ( 24 ) connected.

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