CURTAILED OPERATION OF A WIND POWER PLANT BY DEACTIVATION OF WIND TURBINES

Abstract

The invention relates to a method for operating a group of wind turbines in a wind power plant coupled to a utility grid, comprising the steps of determining that a wind turbine should be deactivated in response to receiving a power curtailment command from the grid, and retrieving data from each wind turbine in the group of wind turbines. Further, the method no comprises ranking all the wind turbines according to a set of ranking criteria and based on the retrieved data, and selecting a wind turbine to be deactivated based on the ranking. Further, the steps of data retrieval and ranking of all the wind turbines including any deactivated wind turbines in the group are repeated at time intervals, and the wind turbine to be deactivated is re-selected based on this updated ranking. The data may include a down time for any presently deactivated wind turbine in the group of wind turbines, reflecting for how long time the wind turbine has been presently deactivated, and the set of ranking criteria may then comprise a pause criterion taking into account the down time.

Claims

1. A method for operating a group of wind turbines in a wind power plant coupled to a utility grid, comprising: determining in response to receiving a power curtailment command from the grid that one or more wind turbines in the group of wind turbines should be deactivated, retrieving data from each wind turbine in the group of wind turbines, ranking all the wind turbines in the group of wind turbines according to a set of ranking criteria and based on the retrieved data, selecting one or more wind turbines in the group of wind turbines to be deactivated based on the ranking, repeating at time intervals the steps of data retrieval and ranking of all the wind turbines in the group of wind turbines including any deactivated wind turbines in the group, and re-selecting one or more wind turbines in the group of wind turbines to be deactivated based on the updated ranking.

2. An operating method according to claim 1 wherein the data includes a down time for any presently deactivated wind turbine in the group of wind turbines, reflecting for how long time the wind turbine has been presently deactivated and wherein the set of ranking criteria comprises a pause criterion taking into account the down time.

3. An operating method according to claim 1 wherein the re-selecting of one or more wind turbines in the group of wind turbines to be deactivated comprises reactivating one or more other wind turbines in the group of wind turbines.

4. An operating method according to claim 1 wherein the data includes the time of power production for each of the wind turbines in the group of wind turbines over a time period.

5. An operating method according to claim 1 wherein the data includes the power produced by each of the wind turbines in the group of wind turbines over a time period.

6. An operating method according to claim 1 wherein the data includes information of the ownership of each wind turbine in the group of wind turbines and the set of ranking criteria comprises an production criterion taking into account the power produced to the grid by each owner over a prescribed period of time.

7. An operating method according to claim 1 wherein the method further comprises selecting a plurality of wind turbines to be de-activated in response to the power curtailment command.

8. An operating method according to claim 1 wherein the determining comprises comparing a power command from the grid to the present power capacity from the group of wind turbines and determining the number of turbines to be de-activated based on the comparison.

9. An operating method according to claim 1 wherein the re-selection of a wind turbine to be deactivated is further based on earlier rankings of the wind turbines in the group of wind turbines.

10. An operating method according to claim 1 wherein the ranking criteria are pre-determined.

11. An operating method according to claim 1 wherein the ranking criteria are changed dynamically.

12. An operating method according to claim 1 wherein the re-selecting is performed at regular prescribed time intervals.

13. An operating method according to claim 1 wherein the set of ranking criteria comprises criteria based on data including one or more of loads, running hours, alarms, fatigue data, user priorities, and power production.

14. A wind power plant comprising a group of wind turbines coupled to a utility grid and comprising a power plant controller configured to perform an operation, comprising: determining in response to receiving a power curtailment command from the grid that one or more wind turbines in the group of wind turbines should be deactivated, retrieving data from each wind turbine in the group of wind turbines, ranking all the wind turbines in the group of wind turbines according to a set of ranking criteria and based on the retrieved data, selecting one or more wind turbines in the group of wind turbines to be deactivated based on the ranking, repeating at time intervals the steps of data retrieval and ranking of all the wind turbines in the group of wind turbines including any deactivated wind turbines in the group, and re-selecting one or more wind turbines in the group of wind turbines to be deactivated based on the updated ranking.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the following different embodiments of the invention will be described with reference to the drawings, wherein:

[0037] FIG. 1 illustrates an exemplary wind power plant coupled to a utility grid and according to an embodiment of the invention, and

[0038] FIG. 2 is a flow diagram of exemplary operations performed by a wind power plant controller, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 illustrates an exemplary wind power plant 100 according to an embodiment of the invention. As illustrated, the wind power plant 100 includes a group of wind turbines (WT) 101 which is coupled to a utility grid 102. The wind turbines 101 are coupled to a power plant controller 103 which controls the operation of the wind power plant 100. The power plant controller 103 may be connected to, or may comprise a Supervisory Control And Data Acquisition (SCADA) system. The wind power plant 100 may include one or more wind turbines 101 which collectively act as a one generating power plant ultimately interconnected by transmission lines with the power grid 102, which may be a three-phase power grid. The wind turbines 101 may be gathered together at a common location in order to take advantage of the economies of scale that decrease per unit cost with increasing output. It is understood by a person having ordinary skill in the art that the wind power plant 100 may include any number of wind turbines of the same or different capacity in accordance with a targeted power output.

[0040] In one embodiment of the invention, the power plant controller 103 may be configured to generate a power reference signals to the group of wind turbines 101. Based on the power reference signal the wind turbines in the wind power plant may adjust one or more operational parameters, e.g., blade pitch angles, so that the wind power plant produces the power defined by the power reference signal. The power reference signal may also be configured to activate and/or deactivate one or more turbines in the group of wind turbines.

[0041] FIG. 2 is a flow diagram illustrating a mode of operation performed by a wind power plant controller according to an embodiment of the invention. As described above, the available wind resources and the power requirement or power demand of the utility grid 102 may vary over time. Therefore, it is possible that the power capability of the wind turbines in the group of wind turbines, P.sub.WPP, exceeds the power required by the grid, P.sub.grid. In such situations, one or more power curtailment commands may be received from the utility grid, requesting that the amount power produced by the wind power plant be curtailed, 201. In such instances, the power plant controller 103 may deactivate one or more turbines 101 in the wind power plant 100 to reduce the amount of power produced.

[0042] According to embodiments of the invention the selection of which one or more wind turbine to deactivate to meet the power curtailment requirement from the power utility grid is determined based upon retrieving data from all the wind turbines WT in the group of wind turbines, 202. Then all the wind turbines are ranked, WT.sub.1, WT.sub.2, WT.sub.3, . . . , 203 according to a set of ranking criteria and based on the retrieved data. Here and in FIG. 2, WT.sub.1 then refers to the wind turbine first in the present ranking, WT.sub.2 second in the ranking and so forth. Each time a ranking is performed, some other wind turbine in the group may then potentially be WT.sub.1 and so forth.

[0043] In one specific embodiment the retrieved data may include data on the down time for any wind turbine in the group which is presently deactivated, 204. By the down time it is understood the time the wind turbine in question has been uninterruptedly deactivated. The down time may then be a parameter (or the only) in one criteria used to rank or prioritize the wind turbines for example so that a first wind turbine is selected to be swapped with another wind turbine in the group if the first wind turbine has been stopped or deactivated for a certain amount of time. Hereby is avoided that any wind turbine in the group can be stopped for too long a time regardless of the power curtailment command is still present or perhaps even increased.

[0044] Upon ranking all the wind turbines in the group of wind turbines, 203, according to the ranking criteria is selected the n wind turbines in the group to be deactivated, WT.sub.1, WT.sub.2, . . . , WT.sub.n, in order to meet the power curtailment requirement, 205, i.e. the first n wind turbines in the latest ranking. The number of turbines to be stopped, n, may be one or more depending on the power curtailment command. These wind turbines are then stopped, 206. This step may further include reactivating the wind turbines which are no longer selected for deactivation in case the ranking has changed compared to earlier.

[0045] After a certain time interval, the data are again retrieved not only from the active wind turbines but also from any deactivated wind turbines. Then the ranking criteria are re-evaluated and all the wind turbines are ranked again according to the updated prioritization. This updated ranking is then used to reselect which wind turbines should be deactivated potentially swapping some of the wind turbines in the group. If the ranking is unchanged as well as the power curtailment requirement from the grid, the active and stopped wind turbines remain the same. In other words the method steps of data retrieval, 202, 204, ranking, 203, and selecting of wind turbines to deactivate and reactivate 205, 206, are repeated at time intervals.

[0046] As mentioned above, the power plant controller 103 may be configured to periodically or continuously collect data from the wind turbines of the group. Examples of data may include, for example, the down time of each wind turbine as described above, data regarding failures, data from sensors (e.g., blade load sensors, tower load sensors), environmental conditions (e.g., wind speed and direction, turbulence), accumulated power production, relative position of the turbines in relation to one or more other turbines given the wind direction, and the like.

[0047] The data considered by the operation method may include fatigue data collected over a lifetime of each wind turbine, such as for example data indicating a total number of failures or faults experienced by each turbine. The total number of failures or stops of each turbine may indicate a long term state of health of the wind turbine. In one embodiment, turbines having a relatively large number of faults and/or failures may be highly prioritized for deactivation.

[0048] In one embodiment of the invention, the retrieved data may include data indicating a total number of alarms or faults associated with each wind turbine over a predefined time window (e.g., the last 4 hours, the last week, or the like). The alarms may include any type of alarm, for example, an alarm caused by a blade sensor indicating that there are excessive loads on the blade which may cause the blade damage or a temperature increase. The total number of alarms for a turbine within a predefined time window may indicate a state of health of the turbine in the short term. In one embodiment of the invention, wind turbines having a relatively high number of alarms in the predefined time window may be given a higher priority for deactivation.

[0049] In one embodiment of the invention, the retrieved data may include data indicating the total amount of power produced by each wind turbine. The total amount of power produced by each turbine may be strongly correlated to the loads experienced by components of the wind turbine, and therefore, the fatigue experienced by the turbine over its lifetime. Accordingly, in one embodiment, wind turbines with a relatively greater amount of lifetime power production may be prioritized for deactivation.

[0050] Other types of retrieved data may include current wind conditions, the relative positions of the wind turbines in the wind power plant, and current wind turbulence data from each of the wind turbines in wind power plant.

[0051] If multiple raking criteria are used to determine which turbines should be activated or deactivated, different relative priorities may be assigned to each criteria to yield the final ranking. For example, suppose a first turbine has experienced 20 lifetime faults and a second turbine has experienced 15 lifetime faults. Accordingly, based on the historical fault data it may seem that the second turbine should be activated and the first turbine deactivated. However, if the second wind turbine is experiencing extreme wind conditions which may damage the turbine, and the first wind turbine is not experiencing extreme wind conditions, then the power plant controller may select the first turbine for activation (even though it has a higher number of lifetime faults), and select the second turbine for deactivation.

[0052] While preferred embodiments of the invention have been described, it should be understood that the invention is not so limited and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.