Method for feeding electrical power into an electrical supply network

Abstract

A method for feeding electrical power into an electrical supply network by means of at least one wind power installation having a power control and a generator, comprising the steps of: creating an electrical power gradient for an electrical power to be generated by the wind power installation wherein the power gradient at least: is limited by means of a stabilization operator or is created by means of a prediction operator in such a way that the electrical power gradient is unequal to a predicted wind power gradient, adjusting the created electrical power gradient in the power control of the wind power installation, generating an electrical power by means of the wind power installation depending on the created electrical power gradient for a feed-in time period with a feed-in time.

Claims

1. A method for feeding electrical power into an electrical supply network using at least one wind power installation including a power controller and a generator, comprising: determining an electrical power gradient for the electrical power to be generated by the at least one wind power installation, wherein the electrical power gradient is at least: limited using a stabilization operator; or determined, using a prediction operator, to be unequal to a predicted wind power gradient; adjusting the electrical power gradient in the power controller of the at least one wind power installation; and generating the electrical power using the at least one wind power installation depending on the electrical power gradient for a feed-in time period having a feed-in time duration.

2. The method as claimed in claim 1, comprising: determining, based on at least one monitored wind parameter, the predicted wind power gradient for a future prevailing wind in a rotor field of the at least one wind power installation for a prediction time period having a prediction time duration.

3. The method as claimed in claim 2, wherein the stabilization operator includes at least one of: a stabilization constant that is less than 1, such that the electrical power gradient is less than the predicted wind power gradient; the stabilization constant that is between 0.4 and 0.6 that the electrical power gradient is less than the predicted wind power gradient; a power limit value for a maximum electrical power of the at least one wind power installation that is less than a maximum wind power predicted using the at least one monitored wind parameter; and a rotational speed limit value for a maximum permissible rotational speed change of the generator and/or a maximum permissible rotational speed of the generator.

4. The method as claimed in claim 3, wherein the prediction operator and/or the stabilization operator are selected such that an end of the feed-in time period is time-shifted after an end of the prediction time period.

5. The method as claimed in claim 3, wherein the prediction operator and/or the stabilization operator are selected such that: the generated electrical power is less than the maximum wind power that is predicted using the at least one monitored wind parameter, or the generated electrical power is less than a maximum energy obtainable from a rotor of the at least one wind power installation.

6. The method as claimed in claim 2, wherein the prediction operator includes at least one of: a prediction constant that is less than 1, such that the electrical power gradient is less than the predicted wind power gradient; the prediction constant that is between 0.4 and 0.6 such that the electrical power gradient is less than the predicted wind power gradient; the prediction constant is selected such that the electrical power gradient results in generating an electrical wind power installation activity beginning at a start of the feed-in time period and ending at the end of the feed-in time period corresponding to a wind activity beginning at a start of the prediction time period and ending at an end of the feed-in time period; a power limit value for a maximum electrical power of the at least one wind power installation that is less than a maximum wind power that is predicted using the at least one monitored wind parameter; and a rotational speed limit value for a maximum permissible rotational speed change of the generator and/or a maximum permissible rotational speed of the generator.

7. The method as claimed in claim 2, wherein the prediction operator is selected such that a beginning of the feed-in time period is time-shifted before a beginning of the prediction time period.

8. The method as claimed in claim 2, wherein: the prediction time duration is not equal to the feed-in time duration, the prediction time duration is less than the feed-in time duration, or the prediction time duration is less than half of the feed-in time duration.

9. The method as claimed in claim 2, wherein: the feed-in time period begins before the prediction time period, and the electrical power is generated, based on the electrical power gradient for the feed-in time period, before the prediction time period.

10. The method as claimed in claim 1, comprising: generating the electrical power using wind power moving through a rotor field of the at least one wind power installation; and mechanically extracting stored, mechanical power from the at least one wind power installation by changing a rotational speed of the generator.

11. The method as claimed in claim 1, wherein the predicted wind power gradient is predicted using a LIDAR system.

12. The method as claimed in claim 11, wherein the LIDAR system is aimed at a sector having a median line substantially perpendicular to a rotor field of the at least one wind power installation or on a normal of prevailing wind.

13. The method as claimed in claim 1, wherein the electrical power gradient is limited using precontrol of the power controller and/or a gradient limiter.

14. The method as claimed in claim 1, wherein feeding the electrical power into the electrical supply network is performed using a mass inertia of the generator.

15. A wind power installation, comprising: a power controller configured to: determine an electrical power gradient for an electrical power to be generated by the wind power installation, wherein the electrical power gradient is at least: limited using a stabilization operator; or determined, using a prediction operator, to be unequal to a predicted wind power gradient; adjust the electrical power gradient in the power controller of the wind power installation; and cause the electrical power to be generated using the wind power installation depending on the electrical power gradient for a feed-in time period having a feed-in time duration.

16. A wind farm, comprising: a plurality of wind power installations including the wind power installation as claimed in claim 15; a wind farm controller; and a LIDAR system.

17. A method for generating an electrical current, comprising: determining an electrical power gradient for an electrical power to be generated by at least one wind power installation, wherein the electrical power gradient is at least: limited using a stabilization operator; or determined, using a prediction operator, to be unequal to a predicted wind power gradient; repeatedly adjusting the electrical power gradient in a power controller of the at least one wind power installation, wherein an adjusted power gradient has an opposite sign and the same magnitude as a power gradient prior to adjustment; and generating the electrical power using the at least one wind power installation depending on the electrical power gradient for a feed-in time period having a feed-in time duration.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The present invention will now be explained in detail below by way of example on the basis of example embodiments with reference to the accompanying figures:

(2) FIG. 1 shows schematically a perspective view of a wind power installation;

(3) FIG. 2 shows schematically a power control of a wind power installation;

(4) FIG. 3 shows schematically the sequence of a method in a block diagram;

(5) FIG. 4 shows schematically the sequence of a preferred method;

(6) FIG. 5 shows schematically the sequence of a particularly preferred method; and

(7) FIG. 6 shows schematically a wind farm.

DETAILED DESCRIPTION

(8) FIG. 1 shows a wind power installation 100, in particular of a wind farm, with a tower 102 and a nacelle 104. A rotor 106 with three rotor blades 108 and a spinner 110 is arranged on the nacelle 104. The rotor 106 moves through a rotor field A.sub.Rotor and is set in rotational motion by the wind, as a result of which a generator in the nacelle 104 is driven. The generator thereby produces an electrical current which is preferably modulated by means of an inverter and is fed into an electrical supply network. The inverter itself is controlled by means of a power control which is configured to carry out a method described above or below.

(9) A LIDAR system 200 is provided in order to carry out the method described above or below by means of the wind power installation 100.

(10) FIG. 2 shows schematically a power control 150 of a wind power installation.

(11) The power control 150 is part of the installation control of the wind power installation and comprises a power input signal P.sub.Input which is converted by the power control 150 by means of a gradient control 152 into a first power gradient dP.sub.1/dt.

(12) This power gradient dP.sub.1/dt created in this way is converted by means of a stabilization operator V or a prediction operator P into an electrical power gradient dP.sub.A_elec/dt which is preferably flatter than the power gradient dP.sub.1/dt.

(13) The electrical power gradient dP.sub.A_elec/dt is then fed to an inverter or to a power control of the wind power installation WT in order to generate an electrical power P.sub.A_elec by means of the wind power installation depending on the created electrical power gradient dP.sub.A_elec/dt for a feed-in time period with a feed-in time.

(14) For this purpose, the stabilization operator V comprises at least, for example, a stabilization constant c.sub.1 which is less than 1, in particular such that the electrical power gradient dP.sub.A_elec/dt is smaller than the wind power gradient dP.sub.W/dt, and furthermore or alternatively a prediction constant c.sub.2 which is between 0.4 and 0.6, preferably 0.5, in particular such that the electrical power gradient dP.sub.A_elec/dt is smaller than the wind power gradient dPw/dt and/or the power gradient dP.sub.1/dt, and furthermore or alternatively a power gradient for a maximum electrical power P.sub.A_max of the wind power installation which is less than a maximum wind power which has been predicted by means of the at least one monitored wind parameter, and furthermore or alternatively a rotational speed limit value of a maximum permissible rotational speed change dω.sub.G_max of the generator and/or a maximum permissible rotational speed ω.sub.G_max of the generator.

(15) For this purpose, the prediction operator P comprises at least, for example, a prediction constant k.sub.1 which is less than 1, in particular such that the electrical power gradient dP.sub.A_elec/dt is smaller than the wind power gradient dP.sub.W/dt, and furthermore or alternatively a prediction constant k.sub.2 which is between 0.4 and 0.6, preferably 0.5, in particular such that the electrical power gradient dP.sub.A_elec/dt is smaller than the wind power gradient dP.sub.W/dt, and furthermore or alternatively a prediction constant k.sub.3 which is chosen in such a way that the electrical power gradient dP.sub.A_elec/dt generates an electrical wind power installation activity beginning with the start of the feed-in time period with the start feed-in time and ending with the end of the feed-in time period with the end feed-in time which essentially corresponds in terms of amount to a wind activity beginning with the start of the prediction time period with the start prediction time and ending with the end of the feed-in time period with the end feed-in time, and furthermore or alternatively a power limit value for a maximum electrical power P.sub.A_max of the wind power installation which is less than the maximum wind power which has been predicted by means of the at least one monitored wind parameter, and furthermore or alternatively a rotational speed limit value of a maximum permissible rotational speed change dω.sub.G_max of the generator and/or a maximum permissible rotational speed ω.sub.G_max of the generator.

(16) The power control is therefore configured to perform a gradient limitation with power limitation as described above or below by means of the stabilization operator V, in particular utilizing reserve power and mass inertia of the rotor.

(17) The power control is therefore also further configured to perform a gradient limitation described above or below with precontrol by means of the prediction operator P, in particular by means of LIDAR and utilizing the mass inertia of the rotor, in particular the rotor-generator system.

(18) In one particularly preferred embodiment, the power control of the wind power installation is configured to switch between a first operating mode with the stabilization operator V and a second operating mode with the prediction operator P.

(19) The power control therefore has two operating modes between which it is possible to switch, in particular according to requirements and/or in response to a signal of a network operator, or if the LIDAR signal is not available, for example due to fog or air that is too pure.

(20) FIG. 3 shows schematically the sequence of a method in a block diagram 300.

(21) The method for feeding electrical power into an electrical supply network by means of at least one wind power installation having a power control and a generator first comprises the step of: creating an electrical power gradient dP.sub.A_elec/dt for an electrical power P.sub.A_elec to be generated by the wind power installation. This is indicated by the block 310.

(22) A stabilization operator V described above or below and/or a prediction operator P described above or below is/are used for this purpose. This is indicated by the block 320.

(23) The creation of the electrical power gradient dP.sub.A_elec/dt is described, in particular, in FIG. 2.

(24) The electrical power gradient dP.sub.A_elec/dt is then adjusted in the power control 150 of the wind power installation. This is indicated by the block 330.

(25) An electrical power P.sub.A_elec is then generated by means of the wind power installation depending on the created electrical power gradient dP.sub.A_elec/dt for a feed-in time period with a feed-in time. This is indicated by the block 340.

(26) FIG. 4 shows schematically the sequence of a preferred method 400, in particular a gradient limitation with power limitation, preferably utilizing a reserve power and mass inertia of the rotor-generator system.

(27) The development of the wind P.sub.W is mapped in the upper diagram 410, said wind having a (predicted) wind power gradient dP.sub.W/dt which results in a rotational speed ω.sub.ROT of the wind power installation.

(28) If a wind gust develops, i.e., if, for example, the wind changes at the time t.sub.p1, this produces a wind power gradient dP.sub.W/dt which changes the rotational speed ω.sub.ROT of the wind power installation. This is shown in the upper diagram 410.

(29) In the lower diagram 420, the electrical power gradient dP.sub.A_elec/dt is then limited by means of a stabilization operator, in particular such that the electrical power gradient dP.sub.A_elec/dt is smaller than the wind power gradient dP.sub.W/dt.

(30) The power limitation results in an electrical wind power installation activity W.sub.A_elec which is less than a wind activity W.sub.W which the prevailing wind makes available.

(31) If the wind gust dies down at a later time t4, a flatter power gradient is similarly used which is, in particular, smaller than a power gradient of the prevailing wind. This can have the result that the wind power installation has to generate more electrical power in a time period [t5; t7] than is obtainable from the prevailing wind. This power deficit is preferably provided by means of a withdrawal W.sub.inertia from the rotor-generator system.

(32) The wind power installation can be operated particularly sparingly on the electrical supply network by means of the stabilization. It is ensured by means of the power limitation that the rotor energy is sufficient to enable a gradient limitation in a negative direction.

(33) FIG. 5 shows schematically the sequence of a particularly preferred method 500, in particular a gradient limitation with precontrol, preferably by means of a LIDAR system and utilization of the mass inertia of the rotor.

(34) The development of the wind P.sub.W is mapped in the upper diagram 510, said wind having a (predicted) wind power gradient dP.sub.W/dt which results in a rotational speed ω.sub.ROT of the wind power installation.

(35) If a wind gust develops, i.e., if, for example, the wind changes at the time t.sub.p1, this produces a wind power gradient dP.sub.W/dt which changes the rotational speed ω.sub.ROT of the wind power installation. This is shown in the upper diagram 510.

(36) In the lower diagram 520, the electrical power gradient dP.sub.A_elec/dt is now limited by means of a prediction operator in such a way that the electrical power gradient dP.sub.A_elec/dt is unequal to a predicted wind power gradient dP.sub.W/dt.

(37) The prediction operator P is chosen in such a way that the feed-in time period with the feed-in time Δt.sub.E begins with a time shift Δt1 before the prediction time period with the prediction time Δt.sub.P.

(38) The gradient limitation therefore results in an electrical wind power installation activity W.sub.A_elec which is essentially equal to the wind activity W.sub.W which the prevailing wind makes available.

(39) It is therefore proposed, in particular, to begin the feed-in of electrical power before the development of the wind gust in order to stabilize the feed-in of the wind power installation. In cases where the wind power installation generates more electrical power than is obtainable from the prevailing wind, energy is extracted mechanically from the wind power installation by changing the rotational speed of the generator, i.e., mechanical activity W.sub.inertia is provided by means of the rotor-generator system.

(40) According to FIG. 5, the power control therefore comprises a precontrol which is achieved by means of a prediction operator which takes account of developing wind conditions.

(41) The wind power installation can be operated particularly sparingly on the electrical supply network by means of the stabilization.

(42) FIG. 6 shows schematically a wind farm 1000, comprising a plurality of wind power installations 100 and a wind farm control 600 which is configured to carry out a method described above or below, in particular using a LIDAR system 200.

(43) For this purpose, the LIDAR system 200 preferably comprises a wind parameter Par.sub.Wind, preferably the wind speed, in order to control the individual wind power installations as above or below depending on this parameter in such a way that the feed-in of the wind power installation 100 or the windfarm 1000 is stabilized.

(44) According to FIG. 6, a power control with a precontrol is similarly proposed which is achieved by means of a prediction operator which takes account, in particular, of the developing wind conditions.

(45) The wind farm control 600 or wind farm control unit (controller) 600 is thus preferably configured to limit the power gradients of the individual wind power installations in such a way that the output power of the wind farm is limited. For this purpose, the same power gradient can be predefined, for example, for each wind power installation, or an individual power gradient which behaves in relation to the rated power of the installation can be predefined for each wind power installation. The latter option is particularly advantageous in relation to mixed farms, i.e., farms which have a multiplicity of wind power installations which are of different types and have different rated powers.