Operating wind turbines in a wind farm during communication interruptions

Abstract

The present invention relates to wind turbines, in particular to controlling a wind turbine during a communication interruption between the wind turbine and a power plant controller. In case of a communication interruption, the wind turbine enters a back-up operation mode, wherein the wind turbine ramps up or down the power production of the wind turbine to a predefined back-up set point.

Description

Technical Field

[0001] This invention relates to a method for operating a wind turbine in a wind power plant during a communication interruption (loss of communication) between the wind turbine and the power plant controller. Background Technology

[0002] When operating wind turbines in wind farms that supply energy to the public power grid, communication interruptions may occur between the wind turbines and the wind farm. These interruptions may be caused by communication failures—that is, a malfunction that disrupts communication. However, they may also be caused by planned maintenance or upgrades to the wind turbines or the wind farm controller.

[0003] During communication outages, wind turbines typically shut down and cease power generation. However, when wind turbines stop generating electricity, it impacts the total output that the wind farm provides to the public grid, and the shutdown of wind turbines can affect the stability of the public grid.

[0004] Therefore, an improved method for controlling wind turbines during communication outages would be advantageous, and in particular, a more efficient and / or reliable method for reducing the impact on power generation for the public grid would be advantageous. Summary of the Invention

[0005] The purpose of this invention

[0006] The present invention can be particularly regarded as providing a method for controlling a wind turbine during a communication interruption between a wind turbine and a wind power plant, thereby reducing the impact of the communication interruption on power production. Invention Overview

[0008] Therefore, in a first aspect of the invention, it is intended to achieve the above-mentioned object and several other objects by providing a method for operating a wind turbine in a wind power plant; the wind power plant includes a power plant controller, and the method includes the following steps:

[0009] - Detect communication interruptions between the wind turbine and the power plant controller by using the wind turbine itself.

[0010] - Upon detecting a communication interruption, the wind turbine enters fallback operation mode.

[0011] - The backup operation mode includes ramping up the power production of the wind turbine to a predefined backup setpoint.

[0012] Wind turbines include a control system. During normal operation, the control system receives an operating setpoint from the power plant controller, and then controls the power generation of the wind turbine based on the operating setpoint received from the power plant controller.

[0013] However, if a communication interruption occurs between the wind turbine and the power plant controller, the wind turbine is controlled by its own control system and does not receive an operating setpoint from the power plant controller. Therefore, when a communication interruption is detected between the wind turbine and the power plant controller, the wind turbine enters a backup operation mode. In backup operation mode, the wind turbine operates according to a predefined backup setpoint to control power production. There may be more than one predefined backup operation setpoint, such as an active power setpoint and a reactive power setpoint.

[0014] The control system is part of the wind turbine, so when writing that the wind turbine is doing something, such as detecting a communication interruption or receiving a setpoint, it should be understood that the wind turbine control system is doing that.

[0015] A wind power plant may include two or more wind turbines. The power plant controller controls the wind power plant and communicates with each wind turbine, sending operating setpoints to each wind turbine and exchanging data with each wind turbine.

[0016] For example, a wind turbine can detect a communication interruption by not receiving any communication from the power plant controller for a period of time, which can be between 500ms and 1, 2, 3, 5 or 10 seconds, or any suitable period of time that can be adjusted by the power plant operator.

[0017] When entering backup operation mode, upon detecting a communication interruption, the wind turbine adjusts its power production to a predefined backup setpoint. This allows the turbine to operate at a predefined safe operating point during a communication interruption, where it can produce electricity without placing unnecessary load on the turbine. The predefined backup setpoint can be stored in the memory of the wind turbine control system for use in the event of a communication interruption. The predefined backup setpoint is preferably an active power setpoint. Power production can be adjusted to the predefined backup setpoint by gradually changing the wind turbine's power production until it matches the predefined backup setpoint. Alternatively, the predefined backup setpoint can be a reactive power setpoint, a voltage setpoint, or a power factor setpoint. The wind turbine can have several predefined backup setpoints stored in memory, and one or more of these predefined backup setpoints can be selected if a communication interruption occurs.

[0018] This invention has, in particular (but not exclusively), the advantage that the wind turbines can survive short-term communication outages (continue operating even in the event of such outages) with minimal impact on power generation. Furthermore, a backup operating mode can be used during system maintenance without shutting down the wind turbines. Therefore, this invention can be used, for example, during software updates to power plant controllers, where the controllers will be inactive for short periods.

[0019] Typically, the power plant controller continuously monitors the power production of a wind farm by measuring the electricity transmitted to the public grid. If power production decreases (potentially due to a communication disruption with the wind turbines), the power plant controller can instruct other wind turbines to increase power production to compensate for the reduced output.

[0020] According to one embodiment, the method further includes: raising or lowering the power production of the wind turbine to a predefined backup setpoint by a predefined rate of increase or decrease or within a predefined time.

[0021] The reduction in active power production can be achieved gradually by decreasing the power production of the wind turbine at a predefined rate of increase or decrease, or by reducing the power over a predefined period of time. In this case, a rate of increase or decrease can be calculated for the wind turbine to reduce the power over the predefined period of time. The predefined period can be 5, 10, 15, 20, 30 minutes, or any suitable time. The predefined period can be adjusted by the power plant operator.

[0022] The speed at which wind turbines can ramp up or slow down their power production to a backup setpoint depends on the ability of the utility grid and other wind turbines in the wind farm to compensate for power fluctuations caused by communication outages.

[0023] According to one embodiment, after detecting a communication interruption, the method includes entering a backup operation mode after a set time delay.

[0024] When a communication interruption is detected, the wind turbine can enter backup operation mode after a set time delay. If the communication interruption is only a minor fault, communication may be re-established within seconds; therefore, the wind turbine will only enter backup operation mode if the communication interruption lasts longer than the set time delay. The set time delay can be 10 minutes or any suitable time, such as 5, 15, 20, or 30 minutes. The set time delay can be adjusted by the power plant operator.

[0025] Alternatively, or additionally, upon detecting a communication interruption, the method may include immediately entering a backup operation mode, but only after a certain period of delay, during which the wind turbine in backup operation mode begins to reduce power production to a predefined backup setpoint in case the communication interruption is re-established.

[0026] According to one embodiment, the method further includes: if the communication interruption is unplanned, reducing the set time delay using a predefined reduction factor.

[0027] If the communication interruption is unplanned, it is likely caused by a system failure. When a system failure occurs, it is preferable to have a reduced time delay before starting to rise or fall to the backup setpoint. Therefore, the time delay can be reduced, for example, by a reduction factor. Predefined reduction factors can be 1 / 4, 1 / 2, 3 / 4, or they can be completely eliminated. Power plant operators can adjust the reduction factor to any suitable factor. Furthermore, when a system failure occurs, it is preferable to be able to rise or fall to the backup setpoint more quickly. For planned communication interruptions, a maintenance reference point may be set in the wind turbine control system to indicate that the communication interruption is planned, or to send a message to the wind turbine prior to a planned communication interruption.

[0028] According to one embodiment, a predefined backup setpoint is determined such that the load on the wind turbine decreases when entering backup operation mode.

[0029] Preferably, a predefined backup setpoint is determined so that the load on the turbine decreases when entering backup operation mode. It may be advantageous for the wind turbine to enter a setting that reduces the load on the wind turbine. According to one embodiment, the load on the wind turbine can be determined using a wind turbine load model. Based on experience and / or calculations, a wind turbine model can be constructed, and a backup setpoint in which the load on the wind turbine is minimized can be determined.

[0030] According to one embodiment, a predefined backup setpoint is determined such that the power production of the wind turbine will decrease or increase to the predefined backup setpoint, wherein the load on the wind turbine is at a local minimum.

[0031] A predefined backup setpoint can be determined by finding the local minimum of the load on the wind turbine and selecting a backup setpoint at that local load minimum.

[0032] According to one embodiment, the predefined backup setpoint is selected from a set of backup setpoints, each of which is a setpoint where the load on the wind turbine is at a local minimum.

[0033] When analyzing the load on a wind turbine, several local minimum values ​​of the load can be determined for different operating setpoints. These different setpoints can be stored in the wind turbine controller as a set of possible backup setpoints. When entering backup operation mode, the wind turbine controller can select one of these backup setpoints. This can be based on the current operating conditions of the wind turbine.

[0034] According to one embodiment, a predefined backup setpoint is selected as the closest setpoint in the set of backup setpoints.

[0035] The predefined backup setpoint selected from this set of backup setpoints can be the setpoint that is closest to the current power production of the wind turbine. By selecting the closest backup setpoint, variations in power production can be minimized.

[0036] According to one embodiment, a predefined backup setpoint is selected as the setpoint that the group of backup setpoints reaches first when power production is reduced.

[0037] The predefined backup setpoint selected from this set of backup setpoints can be a setpoint that is the closest setpoint and is also less than the current power production of the wind turbine.

[0038] According to one embodiment, the method includes the following steps: after entering a standby operation mode, if communication is not re-established after a given time, the wind turbine is shut down.

[0039] When entering backup operation mode, a timer can be started. When the timer runs out after a given time, the wind turbine shuts down power production and stops supplying power to the utility grid. The longer the wind turbine is disconnected from the power plant controller, the greater the risk of it being unable to deliver the expected power and disrupting grid stability. Therefore, the wind turbine will shut down after a certain period. This is preferably after 10 minutes, but can be after any suitable time, such as 5, 15, 20, or 30 minutes. The set time delay can be adjusted by the power plant operator. Alternatively, the wind turbine can not completely shut down production when the timer runs out, but instead reduce power production to a lower level, such as a lower backup setpoint, and then it can restart the timer.

[0040] If the communication interruption is unplanned, the given downtime of the wind turbine can be less than the downtime of the wind turbine in the event of a planned communication interruption.

[0041] According to one embodiment, the method includes the following steps: when communication is re-established, adjusting the power production of the wind turbine to an operating setpoint received from the power plant controller.

[0042] When communication is interrupted and then re-established, the wind turbine will adjust its power production to meet the power plant's needs. After communication is re-established, the wind turbine receives an operating setpoint from the power plant, and then adjusts its power production to match the operating setpoint. The adjustment rate can be determined based on a backup setpoint and / or the received operating setpoint and / or a predefined time period.

[0043] Alternatively, according to one embodiment, the method includes the step of: when communication is re-established, adjusting the power production of the wind turbine to the last known operating setpoint before the communication interruption was detected.

[0044] After communication is re-established, the power plant controller may need some time to calculate the operating setpoint and send it to the wind turbine. While waiting for the operating setpoint from the power plant controller, the wind turbine can use the last known operating setpoint before the communication interruption was detected, assuming that the last received operating setpoint is close to the one that will be received from the power plant controller.

[0045] According to one embodiment, the method includes leaving the standby operation mode upon receiving an operating setpoint or for a period of time after receiving the operating setpoint. When communication is re-established and the wind turbine receives the operating setpoint from the power plant controller, the wind turbine can leave the standby operation mode and resume normal operation. However, the wind turbine may not immediately resume normal operation; instead, it may slowly ramp up and down power production to meet the operating setpoint, and the wind turbine may wait for a period of time before returning to normal operation. Returning to normal operation too quickly can lead to unstable power production, and when a wind turbine returns to normal operation after a period in standby mode, other wind turbines may need time to adjust their power production to meet the requirements of the utility grid.

[0046] Furthermore, according to one embodiment, the wind turbine remains in standby operation mode until its power production reaches the operating setpoint or for a period of time after reaching the operating setpoint. In this case, the wind turbine will remain in standby operation mode until normal power production is re-established, indicating that normal operation does not resume until power production meets the operating setpoint received from the power plant controller.

[0047] In a second aspect, the present invention relates to a control system for operating a wind turbine during a communication interruption, wherein the control system is arranged to perform the steps of the method according to the first aspect of the invention.

[0048] In a third aspect, the present invention relates to a wind turbine comprising a control system according to a second aspect of the invention for operating the wind turbine during a communication outage.

[0049] In a fourth aspect, the present invention relates to a computer program product adapted to enable a computer system comprising at least one computer to control a wind turbine according to a first aspect of the invention, the at least one computer having a data storage device connected thereto, the computer program product being, for example, a computer program product comprising instructions that, when executed by the computer, cause the computer to perform the method of the first aspect of the invention.

[0050] This aspect of the invention is particularly (but not exclusively) advantageous because it can be implemented by a computer program product that, when downloaded or uploaded to a computer system, enables the computer system to perform the operation of the wind turbine of the first aspect of the invention. Such a computer program product can be provided on any computer-readable medium and can also be provided via a network.

[0051] Each aspect of the invention can be combined with any other aspect. These and other aspects of the invention will become apparent from the following description of the embodiments with reference to the description. Attached Figure Description

[0052] The wind power plant and method for controlling the wind power plant according to the invention will now be described in more detail with reference to the accompanying drawings. The drawings show one embodiment of the invention and should not be construed as limiting other possible embodiments falling within the scope of the appended claims.

[0053] Figure 1 A wind turbine is shown.

[0054] Figure 2 This shows an overview of the communication between the power plant controller and the wind turbines in the wind power plant.

[0055] Figure 3 This is a flowchart of the method according to the present invention.

[0056] Figure 4 A state diagram showing the method for controlling a wind turbine is displayed. Detailed Implementation

[0057] Figure 1A wind turbine 100 is shown, comprising a tower 101 and a rotor 102, the rotor 102 having at least one rotor blade 103, such as three blades, extending from a hub 105. The rotor is connected to a nacelle 104, which is mounted on top of the tower 101 and adapted to drive a generator located within the nacelle via a drive system. The rotor 102 can rotate under the influence of wind. The rotational energy of the rotor blades 103 caused by the wind is transferred to the generator via a shaft. Thus, the wind turbine 100 is able to convert the kinetic energy of the wind into mechanical energy by means of the rotor blades, and then into electrical energy by means of the generator. The generator is connected to a power converter, which includes a generator-side converter and a line-side converter. The generator-side converter converts alternating current (AC) to direct current (DC), and the line-side converter converts DC to AC for injection into the public power grid. Furthermore, the wind turbine 100 also includes a control system. The control system can be located within the nacelle 104 or distributed across multiple locations within the turbine 100 and interconnected.

[0058] Figure 2 This diagram illustrates an overview of the communication between the power plant controller 201 and the wind turbine 100 in the wind power plant 200. The wind turbine 100 is connected to an internal medium-voltage network 204, transmitting actual power P to and receiving reactive power Q. The medium-voltage network 204 is connected to a transformer 205, from which voltage is transmitted to a high-voltage network 206, which is connected to the utility power grid 210 via a common coupling point 209.

[0059] The power plant controller 201 measures actual power, reactive power, voltage, and other relevant data at or near the common coupling point 209. Based on the measurements at or near the common coupling point, and preferably also based on the operating parameters of the wind turbine 100, the power plant controller 201 generates a setpoint for the wind turbine 100. The power plant controller 201 communicates with the wind turbine 100 via a communication line 211, which may be wireless. The communication content may include the operating setpoint sent from the power plant controller 201 to the wind turbine 100, and relevant operating parameters sent from the wind turbine 100 to the power plant controller 201.

[0060] Figure 3An example of a possible implementation of the method of the present invention is shown. The wind turbine control system continuously monitors for a communication interruption 301 between the wind turbine and the power plant controller. A communication interruption can be detected by the absence of any communication received from the power plant controller within a certain time period (e.g., 500 ms). When a communication interruption is detected, the wind turbine control system may wait for a set time delay 304, such as five or ten seconds. If no communication is still received from the power plant controller, the control system recognizes that a communication interruption still exists 305. The communication interruption may be a minor fault, and communication may be re-established after a very short time (perhaps only a few seconds). If communication is not re-established after a short time within the set time delay, the wind turbine will enter a backup operation mode 306. In the backup operation mode, the wind turbine control system selects a predefined backup setpoint and adjusts power production to the backup setpoint 307. The selected predefined backup setpoint can be chosen from a set of backup setpoints, where each setpoint represents a local minimum of the load on the wind turbine. For example, depending on whether the communication interruption is planned or unplanned, power production can be adjusted up or down to the backup setpoint quickly or slowly. Furthermore, upon entering backup operation mode, the wind turbine control system starts a shutdown timer 308. If the shutdown timer expires 309, the wind turbine shuts down 310. If the shutdown timer has not expired, and the communication interruption has been detected as ended 311 and communication has been re-established, the wind turbine returns to normal operation 312. When the wind turbine receives the operating setpoint again from the power plant controller, it determines that the communication interruption has ended. The wind turbine then returns to normal operation and adjusts power production up or down to meet the received operating setpoint.

[0061] Of course, the implementation of this method can differ from that described above, because there are many ways to form embodiments according to the method of this invention.

[0062] Figure 4 A state diagram of a method for controlling a wind turbine is shown. The wind turbine operates in normal operation 401, but when a communication interruption occurs 404, the wind turbine changes to a backup operation mode 402. Upon entering backup operation mode, a timer starts, and after a given time, the wind turbine shuts down 403. However, if communication is re-established 405 before the given time has elapsed, the wind turbine returns to normal operation 401.

[0063] Although the invention has been described in conjunction with specific embodiments, it should not be construed as limiting the invention in any way to the described examples. The scope of the invention is determined by the appended claims. In the context of the claims, the terms "comprising" or "including" do not exclude other possible elements or steps. Furthermore, references such as "a" or "an" should not be construed as excluding a plurality. Reference numerals used for elements shown in the figures in the claims should also not be construed as limiting the scope of the invention. Moreover, various features mentioned in different claims may be advantageously combined together, and mentioning these features in different claims does not preclude the possibility and advantage of such combinations.

Claims

1. A method for operating a wind turbine in a wind power plant (200), the wind power plant (200) including a power plant controller (201), the method comprising the following steps: - Detects a communication interruption between the wind turbine (100) and the power plant controller (201). - In the event of a detected communication interruption, the wind turbine (100) enters a backup operation mode (402). - Wherein, the backup operation mode (402) includes adjusting the power production of the wind turbine (100) to a predefined backup setpoint. - Wherein, the predefined backup setpoint is selected from a set of backup setpoints, each backup setpoint being the setpoint where the load on the wind turbine (100) is at a local minimum, and - Wherein, the predefined backup setpoint is selected as the setpoint that is reached first when power production is reduced among the setpoints in the group of backup setpoints.

2. The method according to claim 1, wherein, The power generation of the wind turbine (100) is raised or lowered to the predefined backup setpoint at a predefined rate or within a predefined time.

3. The method according to claim 1 or 2, wherein, Upon detecting a communication interruption, the method includes entering the backup operation mode (402) after a set time delay.

4. The method according to claim 3, wherein, The method includes reducing the set time delay by a predefined reduction factor if the communication interruption is unplanned.

5. The method according to claim 1 or 2, wherein, The predefined backup setpoint is determined such that when the backup operation mode (402) is entered, the load on the wind turbine (100) decreases.

6. The method according to claim 1 or 2, wherein, The predefined backup setpoint is determined such that the power production of the wind turbine (100) is reduced or increased to the predefined backup setpoint, wherein the load on the wind turbine is at a local minimum.

7. The method according to claim 1, wherein, The predefined backup setting point is selected as the closest setting point in the group of backup setting points.

8. The method according to claim 1 or 2, wherein, The method includes the following steps: after entering the backup operation mode, if communication is not re-established after a given time, the wind turbine (100) is shut down (403).

9. The method according to claim 1 or 2, wherein, The method includes the following steps: when communication is re-established, adjusting the power production of the wind turbine (100) to the operating setpoint received from the power plant controller.

10. The method according to claim 9, wherein, The power generation of the wind turbine (100) is raised or lowered to the operating setpoint at a predefined rate or within a predefined time.

11. A control system for operating a wind turbine during a communication interruption, wherein, The control system is configured to perform the steps of the method according to any one of claims 1-10.

12. A wind turbine comprising a control system according to claim 11 for operating the wind turbine (100) during a communication interruption.

13. A computer program product comprising software code, which, when executed on a data processing system, is adapted to control a wind turbine (100), and the computer program product is adapted to perform the method according to any one of claims 1-10.

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