Method of operating at least one wind turbine, and wind turbine or wind turbine park

Abstract

A method for operating at least one wind turbine (1) which is electrically coupled to a power-to-gas converter (4) and to an electrical grid (3), wherein a control unit (5) determines a power level (20) of a power generated by at least one generator (2) of the at least one wind turbine (1) and when the determined power level (20) reaches or exceeds a given lower threshold value (15), at least partially feeds the generated power to the power-to-gas converter (4), wherein when the determined power level (20) reaches or exceeds a given upper threshold value (17), the amount of power fed to the power-to-gas converter (4) remains constant.

Description

[0001] This invention relates to a method for operating at least one wind turbine electrically coupled to a power-to-gas converter and a power grid, wherein a control unit determines a power level of power generated by at least one generator of the at least one wind turbine, and when the determined power level reaches or exceeds a given lower threshold, feeds at least a portion of the generated power to the power-to-gas converter. Additionally, this invention relates to a wind turbine or a wind turbine assembly.

[0002] Wind turbines are highly correlated renewable energy sources. The power generated by a wind turbine depends heavily on the current wind speed. While a relatively constant power output can be achieved once the wind speed reaches a certain threshold, in many cases, wind turbines operate during the unstable portion of their operating time under wind speed conditions where power output is strongly correlated with wind speed.

[0003] If a large portion of the electricity in the grid is supplied by wind turbines, such as offshore wind farms, then sufficient power will be necessary even at low wind speeds. However, this would result in very high power output at higher wind speeds. This could require expanding the grid to handle the large power output, and could also be problematic for economic reasons. An alternative would be to burn off the excess power, for example by heating resistors, controlling the wind turbines to produce less power, or similar wasteful methods. In principle, it would also be possible to use other energy sources, such as gas-fired power plants, within the same grid to compensate for power fluctuations. However, this could be undesirable when the maximum use of renewable energy is expected. To mitigate this problem, it is known from the prior art to use at least a portion of the electricity generated by the wind turbines to drive the electricity to a gas converter, such as an electrolyzer, to produce hydrogen. Examples of this method are disclosed in documents US 5592028 A, US 7075189 A, and US 7199482 A.

[0004] Document US 7471010 recommends using wind turbine towers as gas storage facilities. As discussed, for example, in document WO 02 / 084839 A2, the generated gas can be converted back into electrical energy.

[0005] Document CN 107769 255 A discloses a variable-speed constant-frequency wind power generation system. At low wind speeds and while the wind turbine is rotating at low speeds, the generated electrical energy is of insufficient quality to be fed into the grid, and therefore the electrical energy is specifically fed into an electrolyzer to generate hydrogen. Once the cut-in speed is reached, the generator stops supplying power to the electrolyzer and connects to the grid. Power then increases continuously with increasing wind speed until rated power is reached. Once the wind turbine reaches rated power, the generator additionally supplies power to at least one electrolyzer to further increase the total power.

[0006] A method for providing a relatively constant power level to the grid over a relatively short time interval is discussed in document WO 2013 / 087553 A1. This document suggests predicting minimum wind speeds and therefore minimum power output for a given forecast interval, and then limiting the power level supplied to the grid to or below that level. The remaining electricity is then used to drive a power-to-gas converter. While this method improves the predictability of wind turbine power output, the power level supplied to the grid can still vary significantly over time, especially when using a relatively short forecast interval. However, using long forecast intervals with strong wind speed variations would result in a relatively large reduction in the amount of power that can be output to the grid and would require a relatively large-capacity power-to-gas converter, which could significantly increase the cost of the wind turbine.

[0007] Therefore, the object of the present invention is to provide a method for operating at least one wind turbine that at least partially alleviates the problem of peak power output to the grid when the wind turbine provides a large amount of power, while allowing for a relatively low cost of implementing the wind turbine. Preferably, the method should allow for a relatively constant power output to the grid under a wide variety of operating conditions.

[0008] The problem is solved by the method originally discussed for operating at least one wind turbine, wherein the amount of power fed to the power-to-gas converter remains constant when a determined power level reaches or exceeds a given upper threshold.

[0009] By maintaining a constant power supply to the power-to-gas converter once a determined power level reaches or exceeds an upper threshold, the capacity of the power-to-gas converter used can be freely chosen. As will be discussed in detail below, the capacity of the power-to-gas converter can be selected in a manner such that maximum capacity is reached when the power level supplied to the power-to-gas converter equals the difference between the upper and lower thresholds. This creates a smooth state of power supply to the grid between the lower and higher thresholds, thus ensuring that at least one wind turbine can supply a relatively constant power level to the grid under a wide range of operating conditions. Simultaneously, the capacity of the power-to-gas converter can be relatively low, thus keeping the cost of the wind turbine or wind turbine unit low. Limiting the amount of power supplied to the power-to-gas converter is particularly advantageous when higher power output exceeding the upper threshold is expected only for a relatively short time interval (e.g., a few daily production hours). In this case, using a power-to-gas converter rated for the peak output of the wind turbine would significantly increase costs while only increasing gas production by a relatively small amount. Once the upper threshold is used, the power output to the grid can be used, for example, to compensate for other wind turbines in the wind farm, and thus allow for the maintenance of these wind turbines, etc.

[0010] The power level generated by at least one generator can be measured, for example, by a control unit, or calculated, for example, based on the current wind speed or rotational speed of one or more generators. A wind turbine can be designed such that the generator always feeds at least some power to the grid, at least when the generated power exceeds the power demand of the wind turbine itself.

[0011] When a given power level reaches or exceeds an upper threshold, the power fed to the power-to-gas converter can be kept constant by feeding power exceeding the upper threshold into the grid. Therefore, it is possible, for example, to increase the amount of power fed into the grid until the maximum power output of the wind turbine is reached.

[0012] To avoid damage to the wind turbine or other components that carry the generated electricity, the wind turbine may be switched to a shutdown state once a shutdown threshold for wind speed, blade speed, or similar parameters is reached. For example, it is possible to brake the wind turbine to a complete stop. The initiation of a shutdown state under certain conditions is known from the prior art and will therefore not be discussed in detail. Clearly, during the shutdown process, the power fed to the gas converter and the grid is reduced to zero and therefore does not remain constant.

[0013] When a given power level falls between a lower and an upper threshold, a constant amount of power can be fed to the grid by varying the amount of power supplied to the power-to-gas converter. Preferably, in this case, a non-zero amount of power is fed to the grid. The lower threshold can be considered as the rated power of the wind turbine relative to the grid, which is only exceeded when the upper threshold is reached. If the lower threshold is selected in such a way that it corresponds to only a small fraction of the maximum power that the wind turbine can generate or a small fraction of the upper threshold, the power output to the grid saturates relatively early and remains constant under most operating conditions once the lower threshold is reached.

[0014] When the determined power level is at or below the lower threshold, all power generated by at least one generator, and especially power not used for the operation of the wind turbine itself, can be fed to the grid. In other words, no generated power, or only a small amount of power that might be necessary for the standby mode of the power-to-gas converter, is fed to the power-to-gas converter. Therefore, when the determined power level is at or below the lower threshold, no gas is generated, thus ensuring optimal power output to the grid.

[0015] At very low wind speeds, it may be impossible for a wind turbine to efficiently generate electricity. For example, in such cases, the operation of the wind turbine's electronics may require a significantly greater amount of power than would be generated by the generator. Therefore, it may be possible to use a threshold wind speed below which no electricity is generated, and thus no electricity is supplied to the grid. The upper and / or lower thresholds may be determined during wind turbine production and / or depend on the rated power of the power-to-gas converter and / or may be manually adjusted by the user. Alternatively, the upper and / or lower thresholds may be dynamically determined during wind turbine operation, for example, based on predicted wind speeds and / or current electricity prices and / or other factors.

[0016] User-manual adjustments or dynamic determination of thresholds may be limited by certain factors. For example, it may be possible to allow only threshold adjustments that maintain the difference between thresholds at or below the rated capacity of the power-to-gas converter. This ensures that all additional power generated between thresholds can be fed to the power-to-gas generator. It may also be possible that dynamic or manual adjustments to at least one threshold are limited to a predetermined range, which may, for example, depend on the parameters of the wind turbine. For example, the maximum difference between the wind turbine's maximum power output and an upper threshold may be limited to ensure relatively uniform power output from the wind turbine.

[0017] At least one wind turbine can be designed to provide a given maximum power, wherein a first threshold can correspond to 30% and 50% of the maximum power, and / or wherein an upper threshold can correspond to 75% to 95% of the maximum power. Preferably, the lower threshold can be in the range of 45% and 55% of the maximum power, and particularly can be 40% of the maximum power. The upper threshold can preferably be between 80% and 90% of the maximum power, preferably 85%. If, for example, the rated maximum power output of the wind turbine or wind turbine unit is 10 MW, then the first threshold can be selected as 4 MW, and the second threshold can be selected as 8.5 MW. In this case, for example, it is possible to supply all generated power up to 4 MW to the grid to supply more than 4 MW of generated power up to 4.5 MW to the power-to-gas converter, and to supply the grid with the last 1.5 MW of power that can be generated, thus increasing the power output to the grid to a maximum of 5.5 MW.

[0018] The difference between the upper and lower thresholds can define the necessary capacity of the power-to-gas converter, and can be, for example, between 35% and 55% of the maximum rated power of the wind turbine.

[0019] The maximum power discussed can be the power output of a wind turbine or wind turbine unit at very high wind speeds before it is necessary to shut down the wind turbine or wind turbine unit.

[0020] In a preferred embodiment of the invention, the electrolyzer can be used as an electricity-to-gas converter to generate hydrogen from water. However, it is also possible to generate other gases, such as methane.

[0021] In addition to the method of the present invention, the present invention also relates to a wind turbine or wind turbine unit, comprising at least one generator electrically coupled to a power-to-gas converter of the wind turbine or wind turbine unit and electrically coupled to a coupling device for coupling the generator to a power grid, wherein, during operation of the wind turbine or wind turbine unit, the power distribution between the power-to-gas converter and the power grid is determined by a control unit, wherein the control unit is designed to implement the method of the present invention.

[0022] The gas produced by the power-to-gas converter can be generated within a wind turbine. It can be stored locally within the wind turbine or in a separate storage facility. Alternatively, it can be transported, for example, via pipelines, trucks, or ships to external applications such as storage facilities, processing programs, etc. If hydrogen is produced in gaseous form, it can be converted, for example, directly through the power-to-gas converter itself, or through a separate device that can be used locally and powered by the wind turbine or wind turbine array, or through a separate device (e.g., off-site) into other energy sources including methane or ammonia. Additional gas production allows for the generation of energy for use in non-electrified sectors such as long-haul shipping or aviation.

[0023] Because the methods discussed and the wind turbines or wind turbine units allow for a more uniform power output, a larger amount of power generated by the wind turbines can be used in grids that require a certain amount of available power. Using some power to generate gas also allows for a reduction in the maximum amount of power supplied to the grid, which can be particularly advantageous when the wind turbines or wind turbine units are used in areas with limited grid capacity. This may be relevant, for example, to offshore wind farms.

[0024] Utilizing the inventions discussed, wind turbines or turbine units for offshore wind farms can be less dependent on grid constraints and commercial conditions, and can simultaneously generate chemical energy, i.e., gas. While the use of an additional power-to-gas converter increases initial costs, it hedges against the risk of persistently low electricity prices in the grid. Because overall power output and power output fluctuations are finite, the inventions discussed also allow for the construction of large-scale offshore wind farms in locations with low grid availability, such as islands.

[0025] Other objects and features of the invention will become clear from the following detailed description taken in conjunction with the accompanying drawings. However, the drawings are merely schematic diagrams designed for illustrative purposes only and do not limit the invention. The drawings show:

[0026] Figure 1 This is an exemplary embodiment of a wind turbine according to the present invention, which implements an exemplary embodiment of the method according to the present invention, and

[0027] Figure 2 This is an example output of wind turbine power that depends on wind speed, and it also shows... Figure 1 The threshold values ​​for different operating modes in the wind turbine shown.

[0028] Figure 1 A wind turbine 1 is shown, electrically coupled to a power-to-gas converter 4 and a power grid 3. As shown, a generator 2 is coupled to the power grid 3 and the power-to-gas converter 4 via a control unit 5, which determines the power distribution between the power-to-gas converter 4 and the power grid 3 during operation of the wind turbine 1. Once a certain minimum wind speed is exceeded, wind can rotate the hub 22 via the wind turbine blades 21, and this rotational energy can be converted into electrical energy by the generator 2. The output of the generator 2 is typically alternating current (AC) with a frequency that depends on the rotational speed of the hub 22. Therefore, preferably, the power is regulated before being fed to the power-to-gas converter 4, which should normally operate with direct current (DC), and before being fed to the power grid 3, which typically operates at a fixed frequency. The current supplied to the power grid 3 should also have a fixed phase relationship with the AC current in the power grid 3.

[0029] exist Figure 1 In the example shown, a control unit or a separate unit (not shown) may convert the current supplied by generator 2 into direct current (DC). A portion of this current can be fed directly to the power-to-gas converter 4, and the remainder can be fed to the power grid 3 via a device 6 for coupling generator 2 to the power grid 3. Device 6 may include, for example, a DC / AC converter synchronized with the power grid to provide an output current with the correct frequency and phase. Power distribution can then be controlled, for example, by control device 6.

[0030] Alternatively, for example, it would be possible to use separate power converters for grid 3 and power-to-gas converter 4, and control both power converters to determine power distribution.

[0031] exist Figure 1 In the example shown, the power-to-gas converter is connected to two containers 7 and 8 arranged within the wind turbine 1. Container 7 may store water or different materials that are processed to generate gas, and container 8 may store the generated gas. Alternatively, it would be possible, for example, to supply source materials to the power-to-gas converter 4 via pipes or similar means, and / or to remove the generated gas via pipes or similar means.

[0032] Figure 1The example shown illustrates a single wind turbine with a single generator 2, which has a dedicated control unit 5 and an electric-to-gas converter 4. For multiple wind turbines 1, such as a group of wind turbines in a wind farm, it may also be advantageous to use a common control unit 5 and an electric-to-gas converter 4.

[0033] Now refer to Figure 2 Explain the distribution of the generated power between the power-to-gas converter 4 and the power grid 3. Figure 2 In the diagram, the x-axis 9 represents wind speed, and the y-axis 10 represents the power generated by generator 2 at these wind speeds. The generated power is shown as a percentage of the maximum power 11 that can be provided by wind turbine 1. Power level 20 is maintained at a first power level 13, at which power is not generated until a certain wind speed 12. The generated power then increases to wind speed 14, at which the maximum power 11 is reached. At this point, the generated power saturates until shutdown is required to avoid damage to wind turbine components at wind speed 19. Control unit 5 determines the power level 20 of the power generated by generator 2 and is configured to control the power distribution between grid 3 and power-to-gas converter 4 based on the determined power level 20. Power level 20 can be directly measured or determined from other parameters, such as from measured or predicted wind speed or the rotational speed of hub 22.

[0034] Once the determined power level 20 reaches or exceeds a given lower threshold 15, the control unit feeds at least a portion of the generated power to the power-to-gas converter, thereby reducing the load on the grid. When the determined power level 20 exceeds the upper threshold 17, the power fed to the power-to-gas converter remains constant. In other words, further increases in the determined power level 20 exceeding the upper threshold 17 do not increase the amount of power fed to the power-to-gas converter. Power exceeding the upper threshold 17 is preferably fed to the grid 3. Alternatively, it can be stored in another manner, for example, via batteries.

[0035] Preferably, when the determined power level 20 is between a lower threshold 15 and an upper threshold 17, a constant amount of power is fed to the power grid 3. This can be achieved by specifically feeding power exceeding the lower threshold 15 to the power-to-gas converter until the upper threshold 17 is reached. Preferably, if the determined power level 20 is below the lower threshold 15, no power is supplied to the power-to-gas converter. Therefore, the maximum amount of power supplied to the power-to-gas converter 4 can be the difference between the lower threshold 15 and the upper threshold 17.

[0036] The thresholds 15 and 17 discussed can be fixed during the production of the wind turbine 1, set by the user, or dynamically adjusted. The maximum distance between thresholds 15 and 17 can depend on the capacity of the power-to-gas converter 4 used. Since a large-capacity power-to-gas converter 4 can significantly increase the cost of the wind turbine 1, using the upper threshold 17 to limit the amount of power supplied to the power-to-gas converter 4 can significantly reduce the cost of supplying the wind turbine 1.

[0037] Meanwhile, the discussed method allows for constant power output under a wide range of operating conditions. The power output of the wind turbine to grid 3 can be constant between a lower threshold 15 and an upper threshold 17, and once the maximum power 11 is reached. Therefore, the wind speed is constant between wind speeds 16 and 18 and between wind speeds 14 and 19. Preferably, the difference between the upper threshold 17 and the maximum power is relatively low, for example, in Figure 2 The example shown is 15% of the maximum power 11. If the wind turbine 1 provides, for example, 10 MW of output power, then this difference is equivalent to 1.5 MW. By only supplying power to the grid up to the lower threshold 15, and once the upper threshold 17 is exceeded, and once the lower threshold 15 is exceeded and thus the wind speed 16 is exceeded, the power supplied to the grid 3 thus only varies between the upper threshold 17 and the maximum power 11.

[0038] Therefore, in the example discussed, under a wide range of operating conditions from wind speed 16 to 19, the amount of electricity supplied to the grid will vary by only 1.5 MW. Thus, any power variation exceeding this amount supplied to the grid is limited to rare cases with very low wind speeds below 16.

[0039] Although the invention has been described in detail with reference to preferred embodiments, the invention is not limited to the disclosed examples, and those skilled in the art can derive other variations from the disclosed examples without departing from the scope of the invention.

Claims

1. A method for operating at least one wind turbine (1), said wind turbine (1) being electrically coupled to an electric-to-gas converter (4) and an electrical grid (3), wherein, The control unit (5) determines the power level (20) of the power generated by at least one generator (2) of at least one wind turbine (1), and feeds at least part of the generated power to the power-to-gas converter (4) when the determined power level (20) reaches or exceeds a given lower threshold (15), the method being characterized in that the amount of power fed to the power-to-gas converter (4) remains constant when the determined power level (20) reaches or exceeds a given upper threshold (17).

2. The method according to claim 1, characterized in that, When the determined power level (20) reaches or exceeds the upper threshold (17), the power fed to the power-to-gas converter (4) is kept constant by feeding the power exceeding the upper threshold (17) to the grid (3).

3. The method according to claim 1 or 2, characterized in that, When the determined power level (20) is between the lower threshold (15) and the upper threshold (17), a constant amount of power is fed to the grid (3) by changing the amount of power fed to the power-to-gas converter (4).

4. The method according to claim 1 or 2, characterized in that, When the determined power level (20) is at or below the lower threshold (15), all power generated by the at least one generator (2) and not used for the operation of the wind turbine (1) itself is fed to the grid (3).

5. The method according to claim 1 or 2, characterized in that, The upper and / or lower thresholds (15, 17) are determined during the production of the wind turbine (1) and / or depend on the rated power of the power-to-gas converter (4) and / or are manually adjusted by the user.

6. The method according to claim 1 or 2, characterized in that, The at least one wind turbine is designed to provide a given maximum power (11), wherein the lower threshold (15) corresponds to between 30% and 50% of the maximum power (11), and / or wherein the upper threshold (17) corresponds to between 75% and 95% of the maximum power (11).

7. The method according to claim 1 or 2, wherein the electrolyzer is used as an electricity-to-gas converter (4) to generate hydrogen from water.

8. A wind turbine or wind turbine assembly, comprising at least one generator (2) electrically coupled to a power-to-gas converter (4) of the wind turbine (1) or wind turbine assembly (1) and a coupling device (6) for coupling the generator (2) to a power grid (3), wherein, During operation of the wind turbine (1) or wind turbine unit (1), the power distribution between the power-to-gas converter (4) and the power grid (3) is determined by the control unit (5), wherein the wind turbine or wind turbine unit is characterized in that the control unit (5) is designed to implement the method according to any one of claims 1 to 7.

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