Method for stopping and locking a wind turbine rotor by short-circuiting generator stator windings

Abstract

A method for locking the rotor of a wind turbine includes providing the rotor with at least one rotor blade which can be displaced about its longitudinal axis by an adjusting device from an operating position into a vane position, in which substantially no torque acts upon the rotor. The rotor drives a generator and can be prevented from rotation in a locking position by inserting a locking bolt into a rotor-side receiving opening. A wind turbine for performing the method includes a rotor which is induced into a creeping rotational movement at such a low rotational speed by short-circuiting at least one stator winding of the generator that a locking bolt can be inserted into a rotor-side receiving opening while the rotor is rotating.

Claims

1. A method for locking a rotor of a wind turbine, the rotor configured for driving a generator having at least one stator winding which can be short-circuited in order to brake the rotor into a creeping rotation, the rotor having at least one rotor blade which is adjustable by an adjusting device about a longitudinal axis from an operating position to a vane position in which substantially no torque is exerted on the rotor by wind, the rotor being blocked against a rotation in a locking position by inserting a locking bolt into a rotor-side receiving opening, the method comprising the following steps: moving the wind turbine to an idling mode defined by a state in which the rotor blade is in the vane position by adjusting the at least one rotor blade from the operating position to the vane position; checking a wind direction after moving the wind turbine to the idling mode and tracking a nacelle of the wind turbine to cause a rotor axis of the rotor to point substantially in the wind direction; checking a rotor rotation speed to verify the idling mode; after verifying that the wind turbine is in the idling mode, short-circuiting the at least one stator winding for braking the rotor to initiate the creeping rotation of the rotor, moving the rotor to the locking position with a rotor rotation speed of less than 1 degree/second by adjusting the at least one rotor blade in relation to the vane position depending on the wind speed; and inserting the locking bolt into the receiving opening after reaching the locking position while the rotor is rotating at the rotor rotation speed of less than 1 degree/second.

2. The method according to claim 1, which further comprises adjusting the at least one rotor blade in an angular range of between approximately 95° and 85° relative to a rotation plane of the rotor in order to move the rotor to the locking position.

3. The method according to claim 1, wherein the creeping rotation is defined by a rotor rotation speed between 0.00 and 0.15 degree/second.

4. The method according to claim 1, which further comprises performing the step of: adjusting the at least one rotor blade from the operating position to the vane position manually depending on at least one of a currently prevailing wind speed or wind direction.

5. The method according to claim 1, wherein the step of tracking the nacelle is performed depending on at least one of a currently prevailing wind speed or wind direction.

6. The method according to claim 1, which further comprises: automatically performing the step of inserting the locking bolt into the receiving opening after reaching the locking position.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will be described below using the example of a wind turbine according to the invention for carrying out the above-described method according to the invention with reference to drawings, in which:

(2) FIG. 1 is a schematic illustration of a wind turbine according to the invention, and

(3) FIG. 2 is an electrical equivalent circuit diagram which shows the short-circuited generator during the creeping rotation movement.

DESCRIPTION OF THE INVENTION

(4) As shown in FIG. 1, a wind turbine 1 according to the invention comprises a tower 2, only a detail of which is illustrated, having a nacelle 4 which can be pivoted about the tower longitudinal axis and on which a rotor 6 is held in a rotatable manner by means of schematically indicated bearings 8. The rotor 6 comprises two, three or more rotor blades 10, of which at least one rotor blade 10, but preferably all of the rotor blades, can be rotated about its rotor blade axis 14 by means of a schematically indicated adjusting device 12 in order to rotate said rotor blade out of the illustrated operating position to a position which is called the vane position in which the angle between an imaginary central center plane of the rotor blade 10 and the rotation plane which is spanned by the rotating rotor 6 is 90°.

(5) As can further be gathered from the illustration in FIG. 1, the rotor 6 is drive-coupled to a generator 16 which, in the illustrated embodiment of the wind turbine 1 according to the invention, is designed as a directly driven external rotor synchronous generator of which the radially outer generator rotor 18 is fitted around its inner face with permanent magnets 20 which extend around the stator 22, which is held on the nacelle 4 or on the tower 2 in a manner fixed to a frame, by way of their inner face with a small spacing. A large number of stator windings 24 are arranged opposite the permanent magnets on the stator 22 of the generator 16, said stator windings being interconnected to one another in such a way that an alternating voltage is induced in the stator windings 24 when the rotor 6 rotates, said alternating voltage being tapped off at the three schematically indicated phases 26a, 26b and 26c of the stator windings 24 and being fed to an electrical supply system in a known manner by means of an inverter, not shown, or the like.

(6) As is further shown in the illustration in FIG. 1, a short-circuiting switch 28 is preferably arranged within the nacelle 4, it being possible for said short-circuiting switch to be preferably manually operated by an operator, who is located in the nacelle 4, in accordance with the double-headed arrow 30 in order to electrically short-circuit the three phases 26a, 26b and 26c in relation to one another or to interrupt the short-circuited line connection.

(7) As a result, it is possible, in conjunction with adjusting the rotor blades 10 from the vane position in a range of between preferably approximately 95° and 85° degree in relation to the rotation plane of the rotor 6, to set the rotor 6 into a creeping rotational movement at a rotational speed which is so low that a locking bolt 32, only schematically indicated, which is held in a movable manner in a guide bore 34 which is connected to the stator 22 of the generator 16, or to the nacelle 4, in a manner fixed to a frame, can be inserted into a rotor-side receiving opening 36, which moves together with the rotor 6, while the rotor 6 is rotating, in order to lock said rotor.

(8) FIG. 2 shows the electrical equivalent circuit diagram of the short-circuited generator 16, wherein U.sub.p is the internal phase e.m.f. (voltage, which is generated by movement induction, in a phase), L.sub.h is the main inductance of a phase, L.sub.σ is the stray inductance of a phase, and R.sub.S is the phase resistance of the stator winding 24.

LIST OF REFERENCE SYMBOLS

(9) 1 Wind turbine according to the invention 2 Tower 4 Nacelle 6 Rotor 8 Bearing for the rotor 10 Rotor blade 12 Adjusting device 14 Rotor blade axis 16 Generator 18 Generator rotor 20 Permanent magnets 22 Stator of the generator 24 Stator windings 26a, b, c Phases 28 Short-circuiting switch 30 Double-headed arrow 32 Locking bolt 34 Guide bore which is fixed in a frame 36 Rotor-side receiving opening U.sub.p Internal phase e.m.f. L.sub.h Main inductance of a phase L.sub.σ Stray inductance of a phase R.sub.S Phase resistance of the stator winding