Wind turbine power plant with power saving control method

Abstract

This invention relates to a method for reducing peak power consumption in a grid-connected power plant comprising multiple wind turbines. In response to determining that the power generation value of the power plant is below a power threshold, the following steps are performed: after a first time delay (TD11) for one or more wind turbines in a first group, controlling the first group (WTG1) to initiate a power-saving mode (201) and operate in power-saving mode (201) for a predefined first power-saving period (Tin11) for the first group; and after a first time delay (TD21) for one or more other wind turbines in a second group, controlling the second group (WTG2) to initiate a power-saving mode and operate in power-saving mode for a predefined first power-saving period (Tin21) for the second group. The first time delay (TD11) of the first group is less than the first time delay (TD21) of the second group, and the power-saving mode suppresses power consumption activity of the wind turbines operating in power-saving mode.

Description

Technical Field

[0001] This invention relates to the control of a power plant comprising multiple power generation units, particularly to the control of a power plant having one or more wind turbines, and especially to the handling of power consumption from the grid by the wind turbines under low wind conditions when the wind turbines are shut down. Background Technology

[0002] Yaw operations on wind turbines are used to rotate the nacelle to face the wind in order to maximize energy production, reduce the load on the wind turbine (such as in low wind conditions or when the wind turbine is shut down), or perform cable unwinding operations.

[0003] Performing such yaw operations can be disadvantageous during periods of low wind conditions when wind turbines are not generating electricity, or in other situations where wind turbines are suspended, because they require electricity supplied from the grid.

[0004] Therefore, it is necessary to improve the control of power plants, including wind turbines, in order to handle such yaw activities and other power-consuming activities of wind turbines when they are not producing electricity. Summary of the Invention

[0005] The object of the present invention is to improve the control of power plants including wind turbines to alleviate one of the aforementioned problems, and thus to provide a method for improving the handling of the power consumption activities of wind turbines when the power plant does not produce electricity to the grid or produces insufficient electricity to the grid.

[0006] In a first aspect of the invention, a method for reducing peak power consumption in a power plant is provided, the power plant comprising a plurality of power generation units, the plurality of power generation units comprising a plurality of wind turbines, wherein the power plant is connected to an electrical grid, the method comprising:

[0007] - In response to determining that the power plant's electricity production is below a power threshold (power threshold), the following steps are performed:

[0008] - After a first time delay of one or more wind turbines in the first group, control the first group to activate a power-saving mode and operate in the power-saving mode during a predefined first power-saving period of the first group, and

[0009] - After a first time delay of one or more other wind turbines in the second group, control the second group to activate the power-saving mode and operate in the power-saving mode during a predefined first power-saving period for the second group.

[0010] - Wherein, the first time delay of the first group is less than the first time delay of the second group, and

[0011] - Wherein, the power-saving mode suppresses the power consumption activity of the wind turbine operating in the power-saving mode.

[0012] Advantageously, by setting different time delays for the power-saving modes of each group of wind turbines, power-consuming activities (such as yaw activities, which may be non-critical yaw activities) can be postponed with different delays based on the first and second time delays. The first and second time delays can be predefined time delays, i.e., having predetermined lengths. This method is applicable to two or more groups of wind turbines.

[0013] According to one embodiment, the method includes: after the first power-saving period of the first group ends, controlling the first group to deactivate (disable, stop) the power-saving mode, and after the first power-saving period of the second group ends, controlling the second group to deactivate the power-saving mode, so that the wind turbine can consume electricity.

[0014] Advantageously, by disabling the power-saving mode, each group of wind turbines can consume electricity.

[0015] During the power-saving period, wind turbines are permitted to consume electricity. Since the power-saving period is predetermined, for example, having equal lengths, the power-saving period can be scheduled such that the first and second groups of wind turbines cannot simultaneously activate power-consuming activities, or at least that the first and second groups can only simultaneously engage in power-consuming activities within a limited and predetermined time period.

[0016] According to one embodiment, the deactivation of the power-saving mode for the first group is limited to a second time delay for the first group, while the deactivation of the power-saving mode for one or more wind turbines in the second group is limited to a second time delay for the second group.

[0017] Advantageously, by using a finite time delay, time-shifting (changing over time) delays can be set for different groups of wind turbines, allowing them to consume electricity at different times (which may be non-overlapping or partially overlapping). By determining the allowed times for different groups to consume electricity, the peak power consumption of the power plant can be controlled.

[0018] According to one embodiment, the first time delay of the second group is less than or equal to the sum of the first time delay of the first group and the first power-saving period of the first group. Therefore, the second power-saving period or other subsequent periods can only be delayed to the extent that the second power-saving period begins immediately after the first power-saving period ends.

[0019] According to one embodiment, whenever the power plant's electricity production is below the power threshold, at least one of the first and second groups will be controlled to operate in the power-saving mode at any time after the first time delay of the first group ends. Therefore, at any time after the first time delay of the first group, the peak power consumption will be lower compared to the scenario where all groups are allowed to consume power.

[0020] According to one embodiment, the method includes: sequentially checking whether the power plant's electricity production value is lower than a power threshold; if not (i.e., not lower than the power threshold), then canceling any power-saving mode. In this way, once the power plant produces sufficient electricity, it can operate normally without being restricted by electricity consumption activities.

[0021] According to one embodiment, the electricity production value is based on the actual electricity production of the power plant. This electricity production value is determined based on a combination of the power supplied to the grid (i.e., active power) and the electricity consumption of the wind turbine or power plant. Therefore, when the electricity supplied to the grid is zero, the electricity production value is negative.

[0022] According to another embodiment, the electricity production value is based on the estimated future electricity production of the wind turbine.

[0023] The power consumption activities may include one or more of the following: yaw activity, cable unwinding activity, hydraulic activity, cooling activity, and heating activity.

[0024] According to one embodiment, power-saving modes in each of the corresponding first and second groups are alternately set and deactivated until the power plant's power production value is above the power threshold.

[0025] According to one embodiment, the one or more wind turbines in the first group and the second group are determined based on the power production value of each of the wind turbines, such that the sum of the power production values ​​of the one or more wind turbines in the first group is minimized, and the sum of the power production values ​​of the one or more wind turbines in the second group is second smallest. Therefore, the group with the highest power consumption is first set to the power-saving mode to generate the maximum reduction in peak power consumption from the outset.

[0026] According to one embodiment, the method further includes the following steps:

[0027] - After a first time delay of one or more wind turbines in the third group, control the third group to activate the power-saving mode and operate in the power-saving mode during the first power-saving period of the third group.

[0028] - Wherein, the first time delay of the second group is less than the first time delay of the third group.

[0029] A second aspect of the invention relates to a central controller for controlling the power consumption of a power plant, the power plant comprising a plurality of power generation units including a plurality of wind turbines, wherein the power plant is connected to an electrical grid, and wherein the central controller is arranged to perform the method according to the first aspect.

[0030] A third aspect of the invention relates to a power plant comprising: a plurality of power generation units, the plurality of power generation units including at least one wind turbine; and a central controller according to the second aspect.

[0031] A fourth aspect of the invention relates to a computer program product comprising software code that, when executed on a data processing system, is adapted to control a power plant, and the computer program product is adapted to perform the method described in the first aspect.

[0032] In general, various aspects and embodiments of the present invention can be combined and coupled in any possible manner within the scope of the invention. These and other aspects, features, and / or advantages of the invention will become apparent from and be elucidated by referring to the embodiments described below. Attached Figure Description

[0033] Embodiments of the invention will be described by way of example only, with reference to the accompanying drawings, wherein:

[0034] Figure 1 The image shows a power plant comprising multiple power generation units and wind turbines, as well as...

[0035] Figure 2 A time series diagram is shown, illustrating methods for reducing peak power consumption at power plants. Detailed Implementation

[0036] Figure 1A power plant 100 is shown, comprising multiple power generation units 101 (such as wind turbines 102). Power plant 100 may be a renewable power plant comprising only renewable power generation units. Generally, power generation units 101 may consist of different types of power generation units, such as different types of renewable power generation units, such as solar power units 103 (such as photovoltaic solar panels) and wind turbines. According to one embodiment, power generation units 101 include multiple wind turbines 102. Power plant 100 may include at least two (such as three) identical or different types of power generation units 101, i.e., a mixture of different types of power generation units. For example, power plant 100 may consist only of wind turbines 102, in which case it consists of at least two or three wind turbines 102. In another example, power plant 100 includes at least two wind turbines 102 and at least one or two other power generation units 101.

[0037] The power plant can be connected to the electrical grid 120 to supply power from the power generation unit 101 to the electrical grid and to supply power to the turbine when not producing (electricity).

[0038] At least the wind turbine 102 of the power plant is controlled by a central controller 110. The central controller 110 is configured to control the power generation of the wind turbine 102 according to a power plant reference that defines the desired power supply from the power plant 100 to the grid. The power plant reference can be provided via input 111.

[0039] Furthermore, the central controller is configured to set the operating mode of the wind turbine 102, such as controlling the wind turbine to operate in a power-saving mode, which suppresses the power consumption activity of the wind turbine, thereby reducing power consumption from the grid. The power-saving mode may relate to situations where the wind turbine does not produce electricity or produces only a small amount of electricity (such as under low wind conditions or when the wind turbine is idle). The idle state of the wind turbine can be any state in which the wind turbine does not produce electricity. Similarly, the central controller is configured to control the wind turbine to operate in a normal mode or an enabled power consumption mode, wherein the wind turbine is allowed to consume power from the grid, preferably without restriction.

[0040] When a wind turbine operates in power-saving mode, one or more power-consuming activities are suppressed. Examples of suppressed power-consuming activities include yaw, cable unwinding, hydraulic activity, lubrication, cooling, and heating activities. Therefore, when operating in power-saving mode, at least some power-consuming activities are suppressed or may be prevented from starting, while others cannot be suppressed because they are critical to the continuous operation of the wind turbine. Examples of such critical activities that should not be stopped include communications, load and wind monitoring, and others.

[0041] Wind turbine 102 may include a tower and a rotor with at least one rotor blade (such as three blades). The rotor is connected to a nacelle mounted on top of the tower and is adapted to drive a generator located within the nacelle. The rotor can rotate under the influence of wind. The rotational energy of the rotor blades caused by the wind is transferred to the generator via a shaft. Thus, the wind turbine 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 may include a power converter for converting alternating current (AC) to direct current (DC), and a power inverter for converting DC to AC for injection into the electrical grid. The generator of wind turbine 102 can be controlled to produce electricity corresponding to a power setpoint provided by a central controller 110. For a wind turbine, power production can be adjusted according to the power setpoint by adjusting the pitch of the rotor blades or by controlling the power converter.

[0042] In situations where multiple wind turbines are not producing electricity (e.g., due to their shutdown), certain power consumers on the wind turbines (such as yaw systems, hydraulic systems, cooling systems, and heating systems) may be active, thus drawing power from the grid. For example, the yaw system may be activated for the purpose of performing cable unwinding.

[0043] Even during low-wind periods when wind turbines are paused, they can yaw to face the wind, for example, to minimize tower and blade loads due to oscillations, or to prepare for power generation when wind speeds increase.

[0044] When a turbine yaws into the wind, it is likely to continue yawing in one direction, which can cause the cables within the tower to twist. The twisting capacity of wind turbine cables is limited. Therefore, wind turbines may need to perform a detangle process by controlling the nacelle rotation through the yaw system. The detangle process is preferably performed at low wind speeds, for example, to avoid power generation losses or to avoid the high loads that might occur when performing at high wind speeds.

[0045] Yaws performed to face the wind and yaws performed to deflect the wind consume electricity; that is, the yaw motor of the yaw system consumes power.

[0046] Therefore, when wind turbines draw power from the grid (e.g., due to low production), it may be advantageous to postpone power-consuming activities (such as yaw, unwinding, hydraulic, cooling, heating, or other activities) in order to limit peak power consumption.

[0047] Figure 2 A timeline diagram is shown illustrating a method for reducing peak power consumption at power plant 100 connected to the electrical grid.

[0048] When the central controller 110 determines that the power production value Pprod of the power plant 100 is lower than the power threshold Pt, it can invoke a control method to reduce the peak power consumption of the power plant 100. The power production value includes the power consumption of the wind turbines and therefore may become negative. Therefore, the power threshold Pt can be represented by a negative value, a positive value, or zero. Preferably, the threshold is set such that when the turbines operate in a non-power suppression mode, they draw power from the grid.

[0049] The power production value can be the actual power production measured by the power plant, or a value based on actual power production. The individual power production values ​​(including individual power consumption values) of each wind turbine can be added together to determine the power production value of the power plant, or at least the power production value of its wind turbines. Alternatively, the power production value can be determined based on estimated power production of the wind turbines (such as estimated future power production of the wind turbines). For example, if it is estimated that future power production Pprod will decrease below the power threshold Pt within the next 1-2 minutes, a control method for reducing power peaks can be scheduled to be invoked sometime before the estimated period when the estimated power production crosses the power threshold.

[0050] The time sequence diagram shows the functional relationship between the operating mode of a wind turbine or a group of wind turbines WTG1, WTG2, and WTG3 and time t. Therefore, each group of wind turbines may include one or more wind turbines 102.

[0051] At t=0, the peak power consumption reduction method can be invoked based on the actual or estimated power production value and power threshold.

[0052] For one or more wind turbines in the first group of WTG1, an optional first time delay TD11, such as a predetermined time delay, can be enabled at t=0. Therefore, the operating mode 202 of the first group of WTG1 during TD11 can be the same operating mode that existed before t=0, i.e., the normal operating mode that allows the power consumers of the wind turbines to consume power.

[0053] Once the first time delay TD11 of the first group ends, the operating mode of one or more wind turbines in the first group will be changed to the power saving mode 201 that is planned to occur during the first power saving period Tin11 of the first group.

[0054] For one or more wind turbines in the second group WTG2, the required first time delay TD21 is also activated at t=0, such as a predetermined time delay. Therefore, the operating mode 202 of the second group WTG2 during TD21 can be the same operating mode that existed before t=0, such as the same normal operating mode set for the first group WTG1 during the first time delay TD11.

[0055] Once the first time delay TD21 of the second group ends, the operating mode of one or more wind turbines in the second group will change to the power saving mode 201 that occurs during the predefined first power saving period Tin21 of the second group.

[0056] Similarly, for one or more wind turbines in a possible third WTG3 group, as well as other groups, the required first time delay TD31 will be enabled at t=0, where the third WTG3 group operates in normal mode or a similar mode, where power consumers are allowed to consume power.

[0057] After the first time delay T321 of the third group ends, the operating mode changes to power saving mode 201, which occurs during the first power saving period Tin31 of the third group.

[0058] The first power saving periods Tin11, Tin21, Tin31 and subsequent power saving periods of each group of wind turbines WTG1, WTG2, and WTG3 can have the same length across different groups, although this is not mandatory.

[0059] After each of the first power saving periods Tin11, Tin21, and Tin31, the operating mode of each group of wind turbines WTG1, WTG2, and WTG3 is set to a normal operating mode or another mode that allows the power consumers to consume power during the second time delay periods TD12, TD22, and TD32.

[0060] The durations of the first time delays TD11, TD21, and TD31 in the first, second, and third groups are different, making TD11 less than TD21, and TD21 less than TD31, i.e., TD11 <TD21<TD31。

[0061] In one example, the first time delay of a subsequent group, such as the first time delay TD21 of the second group, must end no later than the end of the first power saving period of the previous group, such as the end of the first power saving period Tin11. That is, TD21 should be less than or equal to TD11+Tin11, i.e., TD21≤TD11+Tin11, or generally TTi+1,1≤TDi,1+Tini,1, where i is the number of the wind turbine in the previous group, and the second index 1 indicates the first time delay.

[0062] like Figure 2 As shown, the second time delay periods TD12, TD22, and TD32 are shifted relative to each other at least because the durations of the first time delays TD11, TD21, and TD31 are different.

[0063] The second time delay periods TD12, TD22, and TD32 can have the same duration, and the subsequent third and subsequent time delay periods of each group can have the same duration as the preceding group.

[0064] After the first power saving period Tin11 of the first group WTG1 ends, the wind turbines in the first group are allowed to consume power during TD12.

[0065] The corresponding activation power consumption period or time delay period TD22 of the second group is delayed by ΔT1 relative to TD12, where ΔT1 = TD21 + Tin21 – (TD11+Tin11), or generally ΔTi = TDi+1,1 + Tini+1,1 –(TDi,1+Tini,1), where i is the number of the wind turbine in the previous group, and the second index 1 indicates the first time delay.

[0066] In one example, when TDi+1,1 - TDi,1 = TDi,2 and Tini+1,1 = Tini,1, for all wind turbines in the WTGi group, ΔTi equals TDi,2. This also applies to subsequent time periods.

[0067] In this scenario, at least within the second time delay period TDi,2, all time delay periods are non-overlapping, allowing only one group of wind turbines to consume power at a time. This reduces the peak power consumption of the power plant, as only one or more wind turbines in a given group can consume power simultaneously.

[0068] In another example, for all wind turbines of group WTGi, and possibly also for subsequent time periods, ΔTi is less than TDi,2, i.e., ΔTi < TDi,2. In this case, the time delay periods of consecutive groups will overlap, but will be postponed. However, by setting ΔTi large enough, at least some of the time delay periods can be non-overlapping. For example, if ΔT1 = 0.5 TD12, then the second time delay period TD32 of the third group will not overlap with the second time delay period TD12 of the first group. Therefore, for the overlapping part, only the power consumption of the first and second groups of WTG1 and WTG2 may occur simultaneously.

[0069] The power consumption activity can start autonomously, for example, in response to sensor measurements, in response to temperature readings, in response to events such as a change in wind direction or a cable winding event, both of which require yaw movement. Alternatively, the power consumption activity can also be scheduled to occur at specific time intervals. However, the power saving mode 201 suppresses the power consumption activity in one or more power consumption activities, for example, by simply rejecting any request to start a power consumption activity, by setting any request to start a power consumption activity on hold, or by postponing any request to start a power consumption activity, for example, by postponing for a certain time or until the power saving mode 201 ends.

[0070] During the time delay periods TD11, TD12,......, TD21, TD22......, the operating mode of the wind turbines can be the same normal operating mode for all wind turbines, or the wind turbines can operate in different operating modes, but all are modes that allow the power consumers of the wind turbines to consume power.

[0071] Generally, as long as the power production value of the power plant is lower than the power threshold, the timing diagram can ensure that at any time after the end of the first time delay TD11 of the first group, at least one of the first and second groups, and possibly other groups, is controlled to operate in the power saving mode 201. To achieve the maximum effect of reducing the power consumption peak, the timing diagram can be determined such that at any time after the end of the first time delay TD11 of the first group, only one group of wind turbines is controlled to operate in the normal mode.

[0072] At least when the predefined power saving periods Tin11 - Tin31 and subsequent power saving periods all have the same length and the time delay periods also have the same length, the relative positions of the time delay periods TD12 - TD32 and subsequent time delay periods are only determined by the different durations of the first time delay periods TD11 - TD31.

[0073] Therefore, in one example, for any group of wind turbines, there is at least a predefined first power-saving period Tin11-Tin31, and optionally subsequent power-saving periods of the same length. Similarly, for any group of wind turbines, there is at least a second time delay period TD12-TD32, and optionally subsequent time delay periods of the same length.

[0074] In one example, the first sum of the first time delay TD11 of the first group, the first power saving period Tin11 of the first group, and the second time delay TD12 of the first group is less than or equal to the second sum of the first time delay TD21 of the second group and the first power saving period Tin21 of the second group, such that only one group of wind turbines can operate power-consuming activities at a time.

[0075] The method includes verifying, for example, at a predetermined time or in response to a change in one or more operating modes (such as activating power-saving mode 201), whether the power generation value of the power plant is still below a power threshold. If the power generation value of the power plant is no longer below the power threshold, then control of the wind turbine according to the time series diagram is deactivated, and any power-saving mode is canceled.

[0076] As long as the power generation value of the power plant remains below the power threshold, or as long as it is permissible to control the wind turbines according to the time sequence diagram, the power saving modes 201 of each WTG1-WTG3 group are alternately set and deactivated, wherein the consecutive power saving modes 201 have time delay periods TD21, TD22, TD32, TD13, ..., TD33.

[0077] Besides the power plant's electricity production exceeding the power threshold, the control of wind turbines according to the time-series diagram may also cease for other reasons. For example, if turbulent wind conditions are detected or predicted, or if certain maintenance operations on the wind turbines are required, the alternating power-saving mode 201 can be stopped.

[0078] Grouping of one or more wind turbines can be determined based on random selection, wear status, remaining life, power production value, or other criteria. For example, considering that these values ​​may be negative because they include power consumption or estimated power consumption, groups can be arranged in ascending order of the sum of the power production values ​​of each wind turbine in each group. In one example, each group may contain only one wind turbine.

[0079] The above-described steps can be coordinated and executed by a central control system that is part of the power plant 100, or by other systems (such as a distributed control system), or some of the steps themselves. The control system can be implemented as an algorithm and executed by one or more computers.

Claims

1. A method for reducing power consumption peaks of a power plant (100), the power plant (100) comprising a plurality of power generating units (101), the plurality of power generating units (101) comprising a plurality of wind turbines (102), wherein, The power plant is connected to the electrical grid, and the method includes: - In response to determining that the power plant's electricity production is below a power threshold, the following steps are performed: - After a first time delay of one or more wind turbines in the first group, control the first group (WTG1) to activate the power-saving mode (201) and operate in the power-saving mode (201) during a predefined first power-saving period of the first group, and - After a first time delay of one or more other wind turbines in the second group, control the second group (WTG2) to activate the power-saving mode and operate in the power-saving mode during a predefined first power-saving period of the second group. - Wherein, the first time delay of the first group is less than the first time delay of the second group, and - Wherein, the power-saving mode suppresses the power consumption activity of the wind turbine operating in the power-saving mode.

2. The method according to claim 1, wherein the method comprises: - After the first power-saving period of the first group ends, control the first group to deactivate the power-saving mode (201), and - After the first power saving period of the second group ends, control the second group to deactivate the power saving mode (201) so that the wind turbine can consume power.

3. The method according to claim 2, wherein, The deactivation of the power saving mode (201) for the first group is limited to the second time delay of the first group, and the deactivation of the power saving mode (201) for one or more wind turbines in the second group is limited to the second time delay of the second group.

4. The method according to any one of claims 1-3, wherein, The first time delay of the second group is less than or equal to the sum of the first time delay of the first group and the first power saving period of the first group.

5. The method according to any one of claims 1-3, wherein, As long as the power plant's power production value is lower than the power threshold, at least one of the first group and the second group will be controlled to operate in the power-saving mode at any time after the first time delay of the first group ends.

6. The method according to any one of claims 1-3, wherein the method comprises: - Check sequentially whether the power generation value of the power plant is lower than the power threshold. If it is not lower than the power threshold, cancel any power saving mode.

7. The method according to any one of claims 1-3, wherein, The electricity production value is based on the actual electricity production of the power plant.

8. The method according to any one of claims 1-3, wherein, The electricity production value is based on the estimated future electricity production of the wind turbine.

9. The method according to any one of claims 1-3, wherein, The power consumption activities include one or more of the following: yaw activity, cable unwinding activity, hydraulic activity, cooling activity, and heating activity.

10. The method according to any one of claims 1-3, wherein, Alternately set and deactivate the power-saving modes of each of the corresponding first and second groups until the power generation value of the power plant is above the power threshold (Pt).

11. The method according to any one of claims 1-3, wherein, The first group and the second group of one or more wind turbines are determined based on the power production value of each of the wind turbines, such that the sum of the power production values ​​of the one or more wind turbines in the first group is minimized, and the sum of the power production values ​​of the one or more wind turbines in the second group is second smallest.

12. The method according to any one of claims 1-3, further comprising: - After a first time delay of one or more wind turbines in the third group, control the third group (WTG3) to activate the power-saving mode and operate in the power-saving mode during the first power-saving period of the third group. - Wherein, the first time delay of the second group is less than the first time delay of the third group.

13. A central controller (110) for controlling the power consumption of a power plant (100), the power plant (100) comprising a plurality of power generation units (101), the plurality of power generation units (101) comprising a plurality of wind turbines, wherein, The power plant is connected to the electrical grid, and the central controller is configured to perform the method according to any one of claims 1-12.

14. A power plant (100), said power plant (100) comprising: Multiple power generation units (101), the multiple power generation units (101) including at least one wind turbine; And the central controller (110) according to claim 13.

15. A computer program product comprising software code adapted to control a power plant (100) when executed on a data processing system, the computer program product being adapted to perform the method according to any one of claims 1-12.

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