Operating a wind turbine of a wind farm

Abstract

A method is proposed for operating at least one wind turbine of a wind farm including determining wind turbine individual offset information based on reactive power provided by the respective wind turbine and reactive power provided by at least one further wind turbine of the wind farm, determining wind turbine individual control information based on the wind turbine individual offset information and wind farm specific control information, operating the at least one wind turbine according to the wind turbine individual control information. Further, a controller and a device as well as a computer program product and a computer readable medium are also provided.

Claims

1. A method for operating at least one wind turbine of a wind farm, comprising the following steps: determining wind turbine individual offset information based on: reactive power provided by the respective wind turbine, and reactive power provided by at least one further wind turbine of the wind farm; wherein the wind turbine individual offset is based on a deviation information that is provided to an input of a processing unit comprising an amplifier and a limiter; determining wind turbine individual control information based on: the wind turbine individual offset information and wind farm specific control information; and operating the at least one wind turbine according to the wind turbine individual control information.

2. The method according to claim 1, wherein the wind turbine individual offset information is determined based on the reactive power provided by the wind turbine and based on a mean value of reactive power provided by the wind turbine and the at least one further wind turbine of the wind farm.

3. The method according to claim 2, wherein the deviation information represents a deviation or difference between the reactive power provided by the wind turbine and the mean value of reactive power.

4. The method according to claim 3, wherein the deviation information is processed by the processing unit, based on at least one out of the following functionalities: applying a gain factor, applying an integration, applying a limiting factor.

5. The method according to claim 2, wherein the mean value of reactive power is weighted by a value of a wind turbine individual weight factor.

6. The method according to claim 2, wherein a wind turbine individual reactive power offset is added to the reactive power provided by the wind turbine.

7. The method according to claim 1, wherein the wind turbine individual control information is determined by adding the wind turbine individual offset information, and the wind farm specific control information.

8. The method according to claim 1, wherein the wind turbine individual control information is representing a wind turbine individual voltage reference controlling the reactive power to be provided by the respective wind turbine.

9. A device comprising and/or being associated with a processor unit and/or hard-wired circuit and/or a logic device that is arranged such that the method according to claim 1 is executable thereon.

10. A non-transitory computer readable medium, having computer-executable instructions adapted to cause a computer system to perform the steps of the method according to claim 1.

11. A controller for operating at least one wind turbine of a wind farm, comprising: a processing unit comprising an amplifier and a limiter that is arranged for: determining wind turbine individual offset information based on reactive power provided by the respective wind turbine, and reactive power provided by at least one further wind turbine of the wind farm; determining wind turbine individual control information based on: the wind turbine individual offset information and wind farm specific control information; and operating the at least one wind turbine according to the wind turbine individual control information.

12. A method for operating at least one wind turbine of a wind farm, comprising the following steps: receiving a reactive power value for the respective wind turbine and at least one further wind turbine of the wind farm; calculating a mean of the reactive power values for the respective wind turbine and the at least one further wind turbine of the wind farm; determining wind turbine individual offset information based on the reactive power value provided by the respective wind turbine and the mean of the reactive power values for the respective wind turbine and the at least one further wind turbine of the wind farm, wherein the wind turbine individual offset information is based on deviation information representing a deviation or difference between the reactive power provided by the wind turbine and the mean value of reactive power values for the respective wind turbine and the at least one further wind turbine of the wind farm, further wherein the deviation information is processed based on at least one of the following functionalities: applying a gain factor, applying an integration, and applying a limiting factor; determining wind turbine individual control information based on the wind turbine individual offset information and wind farm specific control information; and operating the at least one wind turbine according to the wind turbine individual control information.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows an exemplary embodiment of a control scheme for balancing reactive power between several wind turbines of a wind farm;

(3) FIG. 2 shows an alternative embodiment of the proposed control scheme; and

(4) FIG. 3 shows a further alternative embodiment of the present invention.

DETAILED DESCRIPTION

(5) FIG. 1 shows an exemplary control scheme 100 for balancing reactive power between several wind turbines of a wind farm. The control scheme 100 of FIG. 1 may be part of a wind farm controller individually controlling operation of N wind turbines of the wind farm.

(6) According to the exemplary embodiment of FIG. 1 information 111 representing reactive power Q[n] provided by an individual wind turbine (here the n-th wind turbine of the N available wind turbines of the wind farm) is passed to a negative input 116 of an adding element 114. Further, information 110 representing reactive power individually provided by each of the N wind turbines Q[1 . . . N] is forwarded to an input of a calculation element 112 determining a mean value of reactive power based on the information 110. A resulting information 113 representing the mean value of reactive power is forwarded to an adding input 115 of the adding element 114 calculating a difference or deviation between the mean value 113 and the value 111 of individual reactive power Q[n] provided by the n-th wind turbine.

(7) A deviation information 120 provided at an output 117 of the adding element 114 representing a resulting value of the calculation is provided to an input of a processing unit 160 exemplarily comprising an amplifier 121, an integrator 123 and a limiter 125.

(8) According to the exemplary control scheme of FIG. 1 the information 120 is forwarded to an input of the amplifier 121 applying, e.g., a gain factor k to the information 120. Resulting information 122 available at an output of the amplifier 121 is provided to an input of the integrator 123 processing an integration based on the provided information 122. Resulting information 124 at the output of the integrator 123 may be forwarded to limiter 125 generating limited voltage information based on the information 124 wherein resulting wind turbine individual offset information 130 is passed to a first positive input of an adding element 135.

(9) Further, common voltage reference information 140 controlling in general the reactive power to be provided by the wind farm is passed to a second positive input of the adding element 135. The common voltage reference information 140 may be exemplarily provided as wind farm specific control information U.sub.RefPark by a system operator controlling operation of the wind farm. Resulting information 150 representing a value of the sum of the common voltage reference information 140 and the wind turbine individual offset information 130 is provided to an output of the adding element 135.

(10) According to the exemplary control scheme of FIG. 1 the wind turbine individual control information 150 is representing a wind turbine individual voltage reference U.sub.R[n] which might be forwarded to the respective n-th wind turbine thereby controlling the reactive power Q[n] to be provided by that n-th wind turbine based on the control information 150.

(11) The wind turbine individual voltage reference U.sub.R[n] 150 may be provided to a local wind turbine control level of the respective wind turbine being responsible for a proper production of wind turbine individual reactive power according to the control information 150.

(12) FIG. 2 shows an alternative embodiment of the proposed control scheme allowing a faster implementation of the proposed control scheme. The proposed solution 200 as visualized in FIG. 2 is mainly based on the control scheme of FIG. 1, so the same reference numbers are used and reference is made to the respective part of the description. The differing feature to the proposed solution of FIG. 1 is the missing integrator (indicated by the reference number 123 in FIG. 1) in the processing unit 160 of FIG. 2, wherein an output of the amplifier 121 is directly linked to an input of the limiter 125.

(13) FIG. 3 shows a further alternative embodiment 300 of the proposed solution.

(14) Thereby, information 311 representing reactive power Q[n] provided by an individual n-th wind turbine is passed to a negative input 316 of an adding element 314. Further, information 310 representing individual reactive power provided by each of the N wind turbines Q[1 . . . N] is forwarded to a an input (or several inputs according to an alternative embodiment) of an averaging (mean value calculating) element 312 determining a mean value of reactive power based on the information 310. Differing to the solution as shown in FIG. 1 a resulting information 313 representing the mean value of reactive power Q[1 . . . N] provided by all of the N wind turbines of the wind farm is forwarded to an input of a multiplication element 319 multiplying the mean value of reactive power 313 by a value 301 of a wind turbine individual weight factor w[n] provided to a further input of the multiplication element 319. A resulting value 303 representing a weighted mean value is routed to a further positive input 315 of the adding element 314. Differing to the embodiment of FIG. 1 a value 302 representing a wind turbine individual reactive power offset Q.sub.Offset[n] is provided to a further positive input 318 of the adding element 314. Based on the information 303, 302 and 311 provided to the respective inputs 315, 318, 316 a value 320 representing a sum of the provided information 303, 302, 311 is calculated by the adding element 314. The information 320 being available at an output 317 of the calculation element 314, representing the result of the calculation is provided to an input of a processing unit 360 which might have similar functionality like the processing unit 160 as shown in FIG. 1 (comprising, e.g., an amplifier 321, an integrator 323 and a voltage limiter 325), so reference is made to the respective description of FIG. 1

(15) Similar to the scenario of FIG. 1 a resulting information 330 representing wind turbine individual offset information provided via an output of the voltage limiter 325 is passed to a first positive input of an adding element 335 wherein a common voltage reference information 340 controlling the reactive power to be provided by the wind farm is routed to a second positive input of the adding element 335. Resulting information 350 representing a value of the sum of the common voltage reference information 340 and the wind turbine individual offset information 330 is provided to an output of the adding element 335 and may be forwarded as a wind turbine individual control information U.sub.R[n] to the respective n-th wind turbine.

(16) The control scheme 300 as exemplarily shown in FIG. 3, in particular by applying an additional value 301 of a wind turbine individual weight factor w[n] and by applying a value 302 of a wind turbine individual offset based on reactive power Q.sub.Offset[n] allows, e.g., a proper definition of a reactive power balancing strategy like, e.g., controlling wind turbines physically located closer to the PCC to deliver more reactive power than wind turbines having a greater distance to the PCC. Further, the control scheme 300 enables an optimization of a reactive power and voltage control within the wind farm on a Medium Voltage side of a turbine transformer.

(17) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(18) For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements. The mention of a unit or a module does not preclude the use of more than one unit or module.