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Title:
REDUNDANT HYDRAULIC PITCH CONTROL
Document Type and Number:
WIPO Patent Application WO/2019/134972
Kind Code:
A1
Abstract:
The invention relates to a hydraulic circuit (100) for controlling the pitch angle of a plurality of blades (4) of a wind turbine (1). The hydraulic circuit (100) comprises: - a first plurality of actuating cylinders (110), each of said plurality of blades (4) being actuated by one cylinder of said first plurality of actuating cylinders (110), - a second plurality of actuating cylinders (120), each of said plurality of blades (4) being actuated by one cylinder of said second plurality of actuating cylinders (120), - a first accumulator bank (150) comprising at least one first hydraulic fluid accumulator (151, 152), said first accumulator bank (150) being connected to each of said first plurality of actuating cylinders (110), - a second accumulator bank (160) comprising at least one second hydraulic fluid accumulator (161, 162), said second accumulator bank (160) being connected to each of said second plurality of actuating cylinders (120).

Inventors:
SHEIDER, Jonathan (12819 Waterhaven Circle, Orlando, FL, 32828, US)
KNUDSEN, Tommy Hastrup (Jernbanegade 35, 7470 Karup J, 7470, DK)
Application Number:
EP2019/050169
Publication Date:
July 11, 2019
Filing Date:
January 04, 2019
Export Citation:
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Assignee:
SIEMENS GAMESA RENEWABLE ENERGY A/S (Borupvej 16, 7330 Brande, 7330, DK)
International Classes:
F03D7/02; F03D9/17
Foreign References:
GB2071780A1981-09-23
CN105298744A2016-02-03
CN103340056A2013-10-09
EP2458201A12012-05-30
Other References:
None
Attorney, Agent or Firm:
ASPACHER, Karl-Georg (Postfach 22 16 34, M√ľnchen, 80506, DE)
Download PDF:
Claims:
CLAIMS

1. A hydraulic circuit (100) for controlling the pitch angle of a plurality of blades (4) of a wind turbine (1), the hydraulic circuit (100) comprising:

- a first plurality of actuating cylinders (110), each of said plurality of blades (4) being actuated by one cylinder of said first plurality of actuating cylinders (110),

- a second plurality of actuating cylinders (120), each of said plurality of blades (4) being actuated by one cylinder of said second plurality of actuating cylinders (120),

- a first accumulator bank (150) comprising at least one first hydraulic fluid accumulator (151, 152), said first accumulator bank (150) being connected to each of said first plurality of actuating cylinders (110),

- a second accumulator bank (160) comprising at least one second hydraulic fluid accumulator (161, 162), said second accumulator bank (160) being connected to each of said second plurality of actuating cylinders (120).

2. The hydraulic circuit (100) according to claim 1, wherein the hydraulic circuit (100) comprises:

- a first plurality of security valves (180), each security valve of the first plurality of security valves (180) being respectively interposed between the first accumulator bank (150) and one respective actuating cylinder of the first plurality of actuating cylinders (110),

- a second plurality of security valves (190), each security valve of the second plurality of security valves (190) being respectively interposed between the second accumulator bank (160) and one respective actuating cylinder of the second plurality of actuating cylinders (120).

3. The hydraulic circuit (100) according to claim 1 or 2, wherein the hydraulic circuit (100) comprises:

- a first relief valve (153) connected to the first

accumulator bank (150) for controlling the pressure in the at least one first hydraulic fluid accumulator (151, 152), - a second relief valve (163) connected to the second

accumulator bank (160) for controlling the pressure in the at least one second hydraulic fluid accumulator (161, 162) .

4. The hydraulic circuit (100) according to any of the preceding claims, wherein the hydraulic circuit (100)

comprises :

- a first pressure sensor (155) connected to first

accumulator bank (150) for measuring the pressure in the at least one first hydraulic fluid accumulator (151, 152),

- a second pressure sensor (165) connected to second

accumulator bank (160) for measuring the pressure in the at least one second hydraulic fluid accumulator (161, 162) .

5. The hydraulic circuit (100) according to any of the preceding claims, wherein the hydraulic circuit (100)

comprises :

- a first ball valve (154) connected to first accumulator bank (150) for relieving the pressure from the first

accumulator bank (150),

- a second ball valve (164) connected to second accumulator bank (160) for relieving the pressure from the second

accumulator bank (160) .

6. The hydraulic circuit (100) according to any of the preceding claims, wherein any of the first accumulator bank (150) and the second accumulator bank (160) comprises two respective hydraulic fluid accumulators (151, 152; 161, 162).

Description:
DESCRIPTION

Redundant hydraulic pitch control

Field of invention

The present invention relates to a hydraulic circuit for con trolling the pitch angle of the blades of a wind turbine. The hydraulic circuit of the present invention comprises in par ticular redundant features.

Art Background

Normally, any wind turbine is provided with a pitch actuation circuit for regulating the pitch angle of each blade, i.e. the angular position of each blade about the respective blade longitudinal axis. In particular the pitch actuation circuit may be hydraulic . The pitch angle defines the angle of attack of the blades in relationship to the direction of the wind to control the production of power of the wind turbine.

As the regulation of the pitch angle is essential for the functioning of the wind turbine, some level of redundancy is implemented in the pitch actuation circuit.

Typically, in a hydraulic pitch actuation circuit, two hydraulic cylinders are provided for actuating the pitch angle of each blade, one being able alone to control the pitch angle, in case the other fails. The cylinders are connected to a source of hydraulic pressure for normal operations .

Accumulator banks are provided in the hydraulic pitch

actuation circuit for managing emergency where not enough hydraulic pressure is provided by the hydraulic source to the hydraulic cylinders. The principle of redundancy is applied also to the accumulator banks. Each accumulator banks is normally associated to relief valves, security valves and ball valves for relieving pressure.

The great number of components above described provides the required level of redundancy, but produces as drawback also a high level of associated costs and complexity.

It is therefore still desirable to provide a new hydraulic circuit for controlling the pitch angle of the blades of a wind turbine, limiting costs and complexity of the system without compromising the level of redundancy with respect to the above described prior art.

Summary of the Invention

In order to achieve the object defined above, a hydraulic circuit for controlling the pitch angle of a plurality of blades of a wind turbine is provided in accordance to the in dependent claims. The dependent claims describe advantageous developments and modifications of the invention.

According to an aspect of the present invention, a hydraulic circuit for controlling the pitch angle of a plurality of blades of a wind turbine comprises:

- a first plurality of actuating cylinders, each of said plurality of blades being actuated by one cylinder of said first plurality of actuating cylinders,

- a second plurality of actuating cylinders, each of said plurality of blades being actuated by one cylinder of said second plurality of actuating cylinders,

- a first accumulator bank comprising at least one first hydraulic fluid accumulator, said first accumulator bank being connected to each of said first plurality of actuating cylinders ,

- a second accumulator bank comprising at least one second hydraulic fluid accumulator, said second accumulator bank being connected to each of said second plurality of actuating cylinders .

Two accumulator banks are used for managing emergencies for all the first plurality and the second pluralities of actuating cylinders. With respect to prior art circuits where two accumulator banks for each of the three blades of the wind turbine are used, the present invention permits to use two accumulator banks instead of six, without reducing the level of redundancy.

According to exemplary embodiments of the present invention, the hydraulic circuit comprises:

- a first plurality of security valves, each security valve of the first plurality of security valves being respectively interposed between the first accumulator bank and one

respective actuating cylinder of the first plurality of actuating cylinders,

- a second plurality of security valves, each security valve of the second plurality of security valves being respectively interposed between the second accumulator bank and one respective actuating cylinder of the second plurality of actuating cylinders.

Each plurality of security valves comprises a number of valves which corresponds to the number of blades of the turbine. The total number of security valves according to the present invention is the double of the number of the blades. In prior art circuits where two accumulator banks and two hydraulic cylinders for each blade of the wind turbine are used, the total number of security valves is four times the number of the blades. If the wind turbine comprises three blades, the present invention permits to use six security valves instead of twelve, without reducing the level of redundancy .

According to exemplary embodiments of the present invention, the hydraulic circuit comprises:

- a first relief valve connected to the first accumulator bank for controlling the pressure in the at least one first hydraulic fluid accumulator,

- a second relief valve connected to the second accumulator bank for controlling the pressure in the at least one second hydraulic fluid accumulator.

One relief valve is used in association with each accumulator bank. With respect to prior art circuits where two

accumulator banks for each of the three blades of the wind turbine are used, the present invention permits to use two relief valves instead of six, without reducing the level of redundancy .

According to exemplary embodiments of the present invention, the hydraulic circuit comprises:

- a first pressure sensor connected to first accumulator bank for measuring the pressure in the at least one first

hydraulic fluid accumulator,

- a second relief valve connected to second accumulator bank for measuring the pressure in the at least one second

hydraulic fluid accumulator.

One pressure sensor is used in association with each

accumulator bank. With respect to prior art circuits where two accumulator banks for each of the three blades of the wind turbine are used, the present invention permits to use two pressure sensors instead of six, without reducing the level of redundancy.

According to exemplary embodiments of the present invention, the hydraulic circuit comprises:

- a first ball valve connected to first accumulator bank for relieving the pressure from the first accumulator bank,

- a second ball valve connected to second accumulator bank for relieving the pressure from the second accumulator bank. One ball valve is used in association with each accumulator bank. With respect to prior art circuits where two

accumulator banks for each of the three blades of the wind turbine are used, the present invention permits to use two ball valves instead of six, without reducing the level of redundancy .

According to exemplary embodiments of the present invention, any of the first accumulator bank and the second accumulator bank comprises two respective hydraulic fluid accumulators. This permits to conveniently split the fluid reserve in the accumulator bank in two distinct hydraulic fluid

accumulators . Brief Description of the Drawings

The above mentioned attributes and other features and advantages of this invention and the manner of attaining them will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

Figure 1 shows a schematic section of a wind turbine to which the hydraulic circuit present invention can be applied for controlling the pitch angle of a plurality of blades of the wind turbine.

Figure 2 shows a hydraulic scheme, illustrating the hy

draulic circuit of the present invention,

Detailed Description

The illustrations in the drawings are schematic. It is noted that in different figures, similar or identical elements are provided with the same reference signs.

Figure 1 shows a wind turbine 1 according to the invention. The wind turbine 1 comprises a tower 2, which is mounted on a non-depicted foundation. A nacelle 3 is arranged on top of the tower 2.

The wind turbine 1 further comprises a wind rotor 5 having at least one blade 4 (in the embodiment of Figure 1, the wind rotor comprises three blades 4, of which only two blades 4 are visible) . The wind rotor 5 is rotatable around a rota tional axis Y.

The blades 4 extend substantially radially with respect to the rotational axis Y and along a respective longitudinal ax is X . The wind turbine 1 comprises an electric generator 11, in cluding a stator 20 and a rotor 30. The rotor 30 is rotatable with respect to the stator 20 about the rotational axis Y.

The wind rotor 5 is rotationally coupled with the electric generator 11 either directly, e.g. direct drive or by means of a rotatable main shaft 9 and/or through a gear box (not shown in Figure 1) . A schematically depicted bearing assembly 8 is provided in order to hold in place the main shaft 9 and the rotor 5. The rotatable main shaft 9 extends along the ro tational axis Y.

The wind rotor 5 comprises three flanges 15 for connecting a respective blade 4 to the wind rotor 5. A pitch bearing is interposed between each blade flange 15 and the respective blade 4. A hydraulic pitch actuation circuit 100 is associat ed to the pitch bearings of the blades 4 for regulating the pitch angle of each blade, i.e. the angular position of each blade about the respective blade longitudinal axis X.

With reference to the hydraulic scheme of Figure 2 , the hydraulic pitch actuation circuit 100 for controlling the pitch angle of the blades 4 is described.

The hydraulic circuit 100 comprises a first plurality of actuating cylinders 110 and a second plurality of actuating cylinders 120. Each of the plurality of blades 4 are actuated by one cylinder of the first plurality of actuating cylinders 110 and, for redundancy purposes, by one cylinder of the second plurality of actuating cylinders 120. With reference to the wind turbine 1 of figure 1 with three blades 4, each of the first plurality and second plurality of actuating cylinders 110, 120 comprises therefore three cylinders.

For each of the plurality of blades 4, both the first

actuating cylinder 110 and the second actuating cylinder 120 are connected between a source of pressure 200 and a pressure discharge 300. A distribution valve 210 with three positions and four ports is connected between the first actuating cylinder 110 and the source of pressure 200 and the pressure discharge 300 and between the second actuating cylinder 120 and the source of pressure 200 and the pressure discharge 300, in order to assure the regulation of the pitch angle during normal operations. To such purpose, i.e. normal regulation of the pitch angle, the working of the first plurality and second plurality of actuating cylinders 110,

120 and of distribution valve 210 is not a specific object of the present invention and therefore not described in further detail .

To manage emergency cases, where not enough hydraulic

pressure is provided by the hydraulic source 200 to the first hydraulic cylinders 110, the hydraulic circuit 100 comprises a first accumulator bank 150 connected to each of the first plurality of actuating cylinders 110. The first accumulator bank 150 comprises two first hydraulic fluid accumulators 151, 152.

To manage overpressures in the branches connecting the first accumulator bank 150 and the first hydraulic cylinders 110 a first plurality of security valves 180 is provided. Each security valve 180 is respectively interposed between the first accumulator bank 150 and one respective actuating cylinder of the first plurality of actuating cylinders 110. The hydraulic circuit 100 further comprises a first relief valve 153 connected to the first accumulator bank 150 for controlling the pressure in the first hydraulic fluid

accumulators 151, 152. The first relief valve 153 is also connected in a way that it will additionally relieve any overpressure in the first plurality of actuating cylinders 110.

A first pressure sensor 155 is connected to the first

accumulator bank 150 for measuring the pressure in the first hydraulic fluid accumulators 151, 152. A first ball valve 154 is connected to the first accumulator bank 150 for relieving the pressure from the first accumulator bank 150, thus permitting for example the maintenance and/or substitution of any of the first hydraulic fluid accumulators 151, 152.

For redundancy reasons during emergency cases, where not enough hydraulic pressure is provided by the hydraulic source 200 to the second hydraulic cylinders 120, the hydraulic circuit 100 comprises a second accumulator bank 160 connected to each of the second plurality of actuating cylinders 120. The second accumulator bank 160 comprises two second

hydraulic fluid accumulators 161, 162.

To manage overpressures in the branches connecting the second accumulator bank 160 and the second hydraulic cylinders 120 a second plurality of security valves 190 is provided. Each security valve 190 is respectively interposed between the second accumulator bank 160 and one respective actuating cylinder of the second plurality of actuating cylinders 120. The hydraulic circuit 100 further comprises a second relief valve 163 connected to the second accumulator bank 160 for controlling the pressure in the second hydraulic fluid accumulators 161, 162. The second relief valve 163 is also connected in a way that it will additionally relieve any overpressure in the second hydraulic cylinders 120.

A second pressure sensor 165 is connected to the second accumulator bank 160 for measuring the pressure in the second hydraulic fluid accumulators 161, 162. A second ball valve 164 is connected to the second accumulator bank 160 for relieving the pressure from the second accumulator bank 160, thus permitting the maintenance and/or substitution of any of the second hydraulic fluid accumulators 161, 162.

The hydraulic circuit 100 of the present invention permits to achieve the required level of redundancy also during

emergency cases with a total number of:

- two accumulator banks 150, 160,

- six safety valves 180, 190,

- two relief valves,

- two pressure sensors 155, 165,

- two ball valves 154, 164.

In accordance to the present invention the required level of redundancy is achieved by a minimum number of each of the above mentioned components.