Wind turbine power plant with peak power consumption control

Abstract

The invention relates to a method for controlling maximum power consumption of a power plant comprising a plurality of power generating units comprising a plurality of wind turbines, wherein the wind turbines are disconnected from an electrical grid and connected to a power backup system. The method comprises setting a power consumption limit mode of the wind turbines to suppress a predetermined power consumption activity of each wind turbine from being initiated; determining a start-up sequence of groups of at least two of the wind turbines, wherein the start-up sequence comprises a series of different start-up times or non-overlapping start-up time periods; and operating the wind turbines of the groups in accordance with the start-up sequence such that at one of the start-up times or within one of the start-up time periods, only one selection of the plurality of wind turbine selections of the group of wind turbines is initiated or allowed to initiate the predetermined power consumption activity.

Description

Technical Field

[0001] This invention relates to the control of power plants comprising multiple power generation units, particularly to the control of power plants having one or more wind turbines, and especially to the handling of power consumption of wind turbines from a power standby system under conditions of no grid connection. Background Technology

[0002] Yaw activity of wind turbines is used to rotate the nacelles so that they face the wind, with the aim of maximizing energy production and reducing wind turbine load, such as in low wind conditions or when the wind turbine is shut down, or for cable unwinding operations.

[0003] When a wind turbine is disconnected from the grid, its power can be supplied by a backup power system (such as a diesel generator). The size of the backup power system must be determined based on the wind turbine's potential peak power consumption. Since certain power-consuming activities (such as yaw activities) have high initial peak power consumption, determining the size of the backup power system based on the value of this peak power consumption is an issue.

[0004] Therefore, it is necessary to improve the control of power plants, including wind turbines, in order to handle the yaw activity and other power consumption activities of wind turbines when they are disconnected from the grid. 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 therefore to provide a method that provides improved handling of the power consumption activities of wind turbines when the power plant is disconnected from the grid.

[0006] In a first aspect of the invention, a method for controlling the maximum power consumption of a power plant, the power plant comprising a plurality of power generation units, the plurality of power generation units comprising a plurality of wind turbines, wherein the wind turbines are disconnected from the power grid and connected to a power backup system, the method comprising:

[0007] - Set the power consumption limiting mode for the wind turbines to suppress the initiation of predetermined power consumption activities for each wind turbine, including one or more of yaw activity, cable unwinding activity, hydraulic activity, and heating activity.

[0008] - Determine the startup sequence of at least two groups of the wind turbines, wherein the startup sequence includes a series of different startup times or non-overlapping startup periods for predetermined power consumption activities.

[0009] - Operate the wind turbines of the group according to the startup sequence, such that at one point in the startup time or within one period of startup, only one selection of multiple wind turbines in the group is started or a predetermined power consumption activity is allowed to be started.

[0010] For example, power consumption activity is yaw activity. During the transient period of startup (such as a 5-second period), the power consumed by the yaw motor is significantly higher than that consumed during steady-state operation, such as five times the power consumed during steady-state operation. Therefore, if two or more wind turbines initiate yaw operation for a short period of time, the total power consumption can become very high, potentially leading to a failure if it exceeds the nominal capacity of the power backup system. Conversely, the size of the power backup system must be determined based on the worst-case scenario (simultaneous yaw system operation for multiple wind turbines), although this scenario is likely to be low.

[0011] Peak power consumption, i.e., maximum power consumption, can be controlled by operating the power consumption activities of a selection of wind turbines (where each selection may include one or more wind turbines) according to different start-up times or start-up periods. Therefore, it is possible to avoid excessive simultaneous yaw operations by different wind turbines.

[0012] When power-consuming activities involve starting motors (such as yaw drives), inrush currents can occur during startup. If multiple turbines start yaw simultaneously, the combined power required from the backup power system increases, potentially exceeding the system's capacity. Therefore, it is advantageous to operate the group of wind turbines according to their startup sequence, preventing all turbines in the power plant from experiencing simultaneous periods of high power demand due to inrush currents.

[0013] As an example of suppressing power consumption activity, the power consumption activity of a wind turbine can be postponed for a fixed or variable period of time. Therefore, any initiation of power consumption activity can be delayed or otherwise suspended, for example, until the start-up sequence is determined or until operations are initiated according to the start-up sequence.

[0014] The number of wind turbines in the selection, or which wind turbines should be included in the selection, can be determined based on the expected maximum power consumption and peak power consumption or average peak power (e.g., average peak power during a transient peak power period and / or average peak power of different wind turbines). The expected maximum power consumption can be determined based on the nominal power of the power standby system.

[0015] According to one embodiment, a selection of multiple wind turbines is started sequentially or a predetermined power consumption activity is allowed to be started according to the start-up order.

[0016] Since the power consumption activities are initiated sequentially, i.e. time-shifted, it can avoid the overlap of successive transient high-power periods of power consumption activities of different wind turbines.

[0017] According to one embodiment, a startup sequence consisting of different startup times or startup periods is determined such that successive startup times are at least separated by the startup period, or such that a subsequent startup period is located after the end of the previous startup period.

[0018] Therefore, if the duration of the startup period is equal to or longer than the transient high-power period, different startup times can be sufficiently separated to avoid overlap of transient periods from different wind turbines. Similarly, successive startup periods can also be separated by a period of duration equal to or longer than the startup period.

[0019] According to one embodiment, operating a wind turbine to initiate a predetermined power consumption activity includes sending a start-up request that requests one or more wind turbines in the selection to start at one of the start-up times or within one of the start-up periods.

[0020] According to one embodiment, operating a wind turbine to allow the initiation of a predetermined power consumption activity includes sending a start-up permit, allowing one or more wind turbines in the selection to start up at one of the start-up times or within one of the start-up periods.

[0021] Start-up requests or start-up authorizations can be centrally generated and timed by the central control unit and sent to the wind turbines to initiate or enable the initiation of power consumption activities. Start-up requests or start-up authorizations can be sent sequentially to a selection of multiple wind turbines according to the start-up order. Therefore, in order to respond to a start-up request or start-up authorization, the wind turbines must be configured to start or enable the initiation of a predetermined power consumption activity upon receiving the start-up request or start-up authorization.

[0022] According to one embodiment, the method includes:

[0023] - Receive requests from one or more wind turbines to perform predetermined power consumption activities, and

[0024] - Determine the startup order based on the received requests.

[0025] The internal control system of a wind turbine can generate such a request based on input from monitoring functions (e.g., monitoring functions configured to determine whether yaw action or other power-consuming activities are needed based on measurements of wind turbine-specific parameters (such as load values) or environmental parameters (such as wind parameters). Therefore, the startup sequence can be generated only for wind turbines that require power-consuming activities.

[0026] According to one embodiment, operating a wind turbine includes simultaneously running a predetermined power consumption activity on a plurality of wind turbines in at least two selected sets after the end of at least one start-up period.

[0027] Advantageously, the defined startup sequence ensures that the surge periods of the planned power consumption activities do not occur simultaneously, i.e., they do not overlap, thus allowing the planned power consumption activities to be run simultaneously on multiple wind turbine selections.

[0028] A second aspect of the invention relates to a method for determining the power capacity of a power backup system, wherein the power backup system is configured to supply power to a plurality of wind turbines during a period when the wind turbines are disconnected from the power grid, wherein the wind turbines are configured to be controlled according to the method of the first aspect.

[0029] According to one embodiment, determining the power capacity of the power backup system includes:

[0030] - Determine the number of one or more wind turbines allowed to start power-consuming activities at the same time or during the same start-up period, and

[0031] - Determine the power capacity of the power standby system based on the peak startup power consumption of the quantity and power consumption activities.

[0032] Peak startup power consumption can be the average power consumed during the transient peak power period or a portion thereof.

[0033] A third 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 a power backup system, and wherein the central controller is arranged to perform the method according to the first aspect.

[0034] A fourth 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.

[0035] The first aspect of the invention relates to a computer program product comprising software code adapted to control a power plant when executed on a data processing system, and the computer program product being adapted to perform the methods of either the first or second aspect.

[0036] 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 be apparent from and illustrated by reference to the embodiments described below. Attached Figure Description

[0037] Embodiments of the present invention will be described by way of example only, with reference to the accompanying drawings, in which:

[0038] Figure 1 The power plant, which includes multiple power generation units and wind turbines, is shown.

[0039] Figure 2A -B illustrates a method for controlling the maximum power consumption of multiple wind turbines connected to a power backup system. Detailed Implementation

[0040] Figure 1 A 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 (e.g., photovoltaic solar panels) and wind turbines. According to one embodiment, power generation unit 101 includes 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 there are 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.

[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 adapted to drive a generator located inside 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 power grid. The generator of wind turbine 102 can be controlled to produce power corresponding to a power setpoint provided by a central controller 110. For a wind turbine, the output power can be adjusted according to the power setpoint by adjusting the pitch of the rotor blades or by adjusting the power production by controlling the power converter.

[0042] The power plant 100 can be connected to the power grid 120 to supply power from the power generation unit 101 to the power grid.

[0043] Power plant 100 or wind turbine 102 alone may be connected to a backup power system 130, such as a diesel generator, battery, or other backup system capable of supplying power to power plant 100 or at least to wind turbine 102. For example, in the event that power plant 100 is disconnected from the grid 120, backup power system 130 may supply power to the wind turbine to power critical power-consuming activities of the wind turbine.

[0044] 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 supplied from the power plant 100 to the grid. The power plant reference can be provided via input 111.

[0045] In addition, the central controller is also configured to set the operating modes of the wind turbine 102, such as controlling the wind turbine to operate in a peak power reduction mode, which controls the start-up time of one or more power consumption activities of the wind turbine, thereby limiting the peak power consumption (i.e., maximum power consumption) of the power backup system 130. The peak power reduction mode may be relevant when the wind turbine is disconnected from the grid 120, so that only the power backup system 130 can supply power to the wind turbine 102.

[0046] Wind turbines may be in a state where they are not producing electricity or are shut down, such as in low wind conditions. A wind turbine's shutdown state can be any state in which it does not produce electricity. In this state, the wind turbine may be disconnected from the power grid.

[0047] Figure 1 The diagram shows a power plant 100 in a state where it is disconnected from the power grid 120 via one switch and connected to the power backup system 130 via another switch. The switches can be controlled by a central controller 110.

[0048] In power plants connected only to the backup power system 130 but unable to operate in peak power reduction mode, multiple yaw systems may initiate yaw simultaneously, or at least within a few seconds. The initial transient surge current consumed by the multiple yaw motors starting simultaneously draws peak power from the backup power system 130. The yaw motor initiation transient can last for several seconds, such as up to 5 seconds, and the power consumption during this transient period can be, for example, five times higher than the steady-state power consumption. Therefore, if two or more wind turbines initiate yaw within the same transient period, the total power consumption will be significantly greater than the sum of the power consumed during the steady-state yaw period.

[0049] In a power plant 100 configured according to an embodiment of the invention, when a wind turbine operates in a peak power reduction mode, the autonomous initiation of one or more power-consuming activities can be suppressed or otherwise prevented. Examples of such suppressed power-consuming activities include yaw, cable unwinding, hydraulic activity, lubrication, cooling, and heating activities. Examples of suppressed power-consuming activities may be activities that require being in a state where they can be activated, thereby consuming electricity from the power standby system 130. For example, the yaw system may be required to be activated at least for a known period of time to perform cable unwinding or yaw to face the wind, for example, to minimize tower and blade loads due to oscillations, or to be ready to generate electricity when wind speeds increase. The power consumption characteristics of such power-consuming activities may include initial power transients (transient power) or surge power or current, followed by steady-state current consumption. Power transients may be caused by the initial surge current required for the initial energization of the electromagnetic motor. Power transients may be significantly higher than steady-state power; for example, transient power may be 1.5 times higher than steady-state power, such as 2 times or more.

[0050] When a turbine yaws to face the wind, it is likely to yaw continuously in one direction, which can cause cable twisting within the tower. Wind turbine cables have limited torsional capacity. 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 high loads that might otherwise be generated during high wind speeds.

[0051] Other power-consuming activities can be left unsuppressed because they are essential for the continuous operation of the wind turbine. Examples of such important activities that should not be shut down include communications, load, and wind monitoring.

[0052] Multiple wind turbines 102 constitute a wind turbine group 141, within which a selection set 142 of wind turbines can be selected, wherein each selection set 142 includes one or more wind turbines. Selection can be made manually based on wind turbine characteristics (such as load history) or environmental data (such as actual or historical wind data).

[0053] Figure 2A and Figure 2B The diagram illustrates a method for controlling the maximum power consumption of multiple wind turbines connected to a power backup system 130. Curve 201 illustrates the sum of power consumption activities when different wind turbines 102 or different selections 142 are started sequentially.

[0054] The first power peak 221 between t1 and t2, or during the first startup period 211, is a transient power consumption caused by the inrush current of the power consumption activity of one or more wind turbines in the first selection. During the period between t1 and t2, or near the end of the first startup period 211, the transient power 221 decreases to a steady-state power, which persists as long as the power consumption activity of the first selection continues. Shortly after t2, the power consumption activity of one or more wind turbines in the second selection starts, resulting in a second transient power peak 222 between t2 and t3, or during the second startup period 211. The power consumption of the power consumption activity of the second selection (which persists as steady-state power after t3) is added to the power consumption of the first selection. Shortly after t3, the power consumption activity of one or more wind turbines in the third selection starts, resulting in a third transient power peak 223. The power consumption of the power consumption activity of the third selection (also persists as steady-state power) is added to the power consumption of both the first and second selections. Since the power consumption activities of the first to third selections are scheduled to start at different times or are allowed to occur in different periods, the peak power consumption 221-223 does not overlap in time, but is arranged to occur sequentially, or so that the peak power consumption 221-223 does not overlap.

[0055] Therefore, while this arrangement ensures that peak power consumption does not overlap, steady-state periods of arranged power consumption activity occurring simultaneously for multiple different selections of wind turbines are permitted. For example, as Figure 2A and Figure 2B As shown, after t2 or during the second start-up period 211, the predetermined power consumption activities of the first and second selected wind turbines are operated simultaneously, and after t3 or during the third start-up period 211, the predetermined power consumption activities of the first to third selected turbines are operated simultaneously.

[0056] Initially at t0, a power consumption limiting mode is set for one or more wind turbines to suppress the initiation of predetermined power consumption activities (such as yaw activities) for each wind turbine.

[0057] A predetermined startup sequence for the power consumption activities of multiple wind turbines is obtained, for example, determined by a central controller 110 or provided manually. This startup sequence includes a series of different startup times t1, t2, t3 and / or non-overlapping startup periods 211.

[0058] In order to allow suppressed power consumption activity to operate, wind turbine 102 (e.g., by central controller 110) is operated according to the startup sequence to start the power consumption activity of a selection 142 of wind turbines (e.g., one wind turbine 102) at or near startup times t1, t2, t3, or to allow it to start during startup period 211.

[0059] The wind turbines in selection 142 may include one or more wind turbines from group 141 of wind turbines. If two power-consuming activities are allowed to start simultaneously, thereby consuming transient power simultaneously, then the wind turbines in selection may include two wind turbines.

[0060] For example, a predetermined power consumption activity of a wind turbine or a selection of wind turbines can be initiated by sending an activation request to the wind turbine or a selection of wind turbines, requesting that the power consumption activity be initiated at one of activation times t1, t2, t3, or within one of the activation periods 211.

[0061] Startup times t1, t2, and t3 can be spaced out, such that the time between successive startup times t1 and t2 is long enough to ensure that the transient power consumption period has ended before the subsequent startup time t2. For example, the time interval can be equal to the length of startup time 211.

[0062] By defining a startup period 211, the wind turbine's control system can autonomously determine whether a power-consuming activity needs to be initiated. For example, a startup period 211 can have a duration of several seconds, such as a fixed duration of 1 to 100 seconds. To ensure that a transient peak power consumption period initiated during startup period 211 (e.g., due to inrush current from the yaw drive / motor) has ended before subsequent power-consuming activities are initiated in subsequent startup periods 211, a delay period 212 with an appropriate duration (e.g., the duration of the transient peak power consumption period) can be defined between any successive startup periods 211.

[0063] Controlling the predetermined startup sequence of power consumption activities may involve sending startup authorization (such as an enable signal) that allows one or more wind turbines of the selection 142 to start only at one of startup times t1-t3 or within one of startup periods 211. Therefore, power consumption activities will only start, for example, if the control system of wind turbine 102 requests the startup of a power consumption activity.

[0064] Alternatively, control of the start-up sequence of predetermined power consumption activities may involve sending a start-up request that only requests one or more wind turbines of the selection 142 to start at one of the start-up times t1-t3 or within one of the start-up periods 211.

[0065] A startup request or startup authorization can be sent sequentially to multiple wind turbine selections based on the startup order, or the startup request or startup authorization can be sent in a single operation, for example, when the power consumption limit mode is set at t0 or at another time before the first startup time t1 or at t1.

[0066] Understandably, wind turbines (such as wind turbine control systems) are configured to enable them to initiate or enable predetermined power consumption activities in response to receiving a start request or start permission.

[0067] Wind turbines can send requests to central controller 110 to initiate suppressed power consumption activity. Therefore, central controller 110 can be configured to determine the start-up sequence based on polling requests from wind turbines. The processing of requests, such as the ordering of requests in the start-up sequence, can be determined based on auxiliary data such as wind speed or tower load for a given wind turbine.

[0068] Alternatively, the startup sequence can be a predetermined sequence, such as one provided by the operator of power plant 100.

[0069] A power backup system is configured to supply power to multiple wind turbines in the event of a grid disconnection. Therefore, the size of the power backup system should be determined to provide the maximum power under worst-case conditions over a given time period. Based on the method for controlling the maximum power consumption of power plant 100, the number of one or more wind turbines allowed to operate simultaneously for a given power consumption activity is known or can be determined.

[0070] Similarly, since the peak power consumption of power consumption activities is known, the total power consumption is also known or can be determined. Based on this knowledge, the required power capacity of the power standby system can be determined, for example, based on the number of power consumption activities allowed to operate simultaneously and their peak power consumption, such as the average peak power consumption during the transient start-up period of a power consumption activity. Therefore, methods for controlling the maximum power consumption of a power plant can be used in methods for determining the required power capacity of a power standby system.

[0071] The above-described method steps can be coordinated and executed by a central control system 110, which is part of the power plant 100, or by other systems (such as a distributed control system) performing the method steps or some of them. The control system can be implemented as an algorithm and executed by one or more computers.

Claims

1. A method for controlling the maximum 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 (102), wherein, The wind turbine is disconnected from the power grid and connected to a backup power system (130), the method comprising: - Set a power consumption limiting mode for the wind turbines to suppress the initiation of predetermined power consumption activities for each wind turbine, wherein the power consumption activities include one or more of yaw activities, cable unwinding activities, hydraulic activities, and heating activities. - Determine the startup sequence of at least two groups (141) of the wind turbines, wherein the startup sequence includes a series of different startup times (t1, t2, t3) or non-overlapping startup periods (211) of predetermined power consumption activities, and - Operate the wind turbines of the group according to the startup sequence, such that at one of the startup times or within one of the startup periods, only one selection (142) of the multiple selections of wind turbines in the group is started or allowed to start a predetermined power consumption activity. Operating the wind turbines includes simultaneously running the predetermined power consumption activity on multiple wind turbines in at least two selected sets after the end of at least one start-up period (211).

2. The method according to claim 1, wherein, The predetermined power consumption activity is initiated sequentially or allowed to be initiated according to the startup sequence of a selection of multiple wind turbines.

3. The method according to claim 1 or 2, wherein the method comprises: Determine the startup sequence consisting of different startup times or startup periods, such that successive startup times (t1, t2, t3) are at least separated by the startup period (211), or such that the subsequent startup period is located after the end of the previous startup period.

4. The method according to claim 1 or 2, wherein, Operating the wind turbines to initiate the predetermined power consumption activity includes sending a start request to request one or more wind turbines in the selected set to start at one of the start times (t1, t2, t3) or within one of the start periods (211).

5. The method according to claim 4, wherein, Operating the wind turbines to allow the initiation of the predetermined power consumption activity includes sending a start-up permit, allowing one or more of the selected wind turbines to start at one of the start-up times (t1, t2, t3) or within one of the start-up periods (211).

6. The method according to claim 5, wherein, The startup request or startup permission is sent sequentially to multiple wind turbine selection sets according to the startup order.

7. The method according to claim 5, wherein, The wind turbine is configured to start or enable the predetermined power consumption activity in response to receiving the start request or start permission.

8. The method according to claim 1 or 2, wherein the method comprises: - Receive requests from one or more of the wind turbines to perform the predetermined power consumption activity, and - The startup order is determined based on the received request.

9. A method for determining the power capacity of a power backup system (130), wherein, The power backup system is configured to supply power to multiple wind turbines in the event that the wind turbines are disconnected from the power grid, wherein the wind turbines are configured to be controlled by the method according to any one of claims 1-8.

10. The method of claim 9, wherein, The method includes: - Determine the number of one or more wind turbines allowed to start the power-consuming activity at the same time or within the same start-up period, and - Determine the power capacity of the power backup system based on the quantity and the peak startup power consumption of the power consumption activity.

11. A central controller (110) for controlling the power consumption of a power plant (100), the power plant comprising a plurality of power generation units (101), the plurality of power generation units (101) comprising a plurality of wind turbines (102), wherein, The power plant is connected to a power backup system (130), and the central controller is configured to perform the method according to claims 1-8.

12. A power plant (100), said power plant (100) comprising: Multiple power generation units (101) include at least one wind turbine (102). And the central controller (110) according to claim 11.

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

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