Method of managing dynamic response to wind in solar tracker array

Abstract

A method of managing a dynamic response to wind in a solar tracker array is provided. The method includes determining a wind speed, comparing the wind speed to a predetermined threshold to determine whether the wind speed equals or exceeds the predetermined threshold, positioning a windmost solar tracker to a predetermined angle based on the comparison, and positioning a leemost solar tracker to the predetermined angle based on the comparison. The solar trackers are positioned at the predetermined angle at a predetermined interval starting at the windmost solar tracker, and the remaining solar trackers remain in normal operating conditions.

Description

[0001] Divisional Application Information

[0002] This application is a divisional application of the invention patent application with the application date of November 19, 2019, application number 201980076033.5, and invention name “Gradual folding of solar tracker and method thereof”. Technical Field

[0003] The present invention relates to solar power generation systems, and more particularly to solar tracker actuation systems for adjusting the orientation of solar power generation components to track the position of the sun. Background Art

[0004] Solar cells and solar panels are most efficient in sunny conditions when they are angled toward the sun. Many solar panel systems are designed in combination with solar trackers, which follow the sun's path across the sky from east to west in order to maximize the system's power generation capabilities. The relatively low energy generated by a single solar cell requires the use of thousands of solar cells arranged in an array to generate enough energy to be used, for example, as part of an energy grid. As a result, solar trackers have been developed that are quite large, spanning hundreds of feet in length.

[0005] Adjusting the massive solar trackers requires power to drive the solar array as it follows the sun. As will be appreciated, the larger the load, the greater the amount of power required to drive the solar tracker. An additional design constraint for such systems is the stiffness required to accommodate the weight of the solar array and the sometimes large wind loads.

[0006] Furthermore, the torsional excitation caused by wind loads exerts large forces on the structure used for support and the mechanism used to articulate the solar tracker. Thus, at various locations along the length of the solar tracker, it is necessary to increase the size and number of components to reduce the torsional excitation. The present invention seeks to address the shortcomings of existing tracker systems. Summary of the invention

[0007] The present invention relates to a method of managing a dynamic response to wind in a solar tracker system. The method comprises determining a wind speed, comparing the wind speed to a predetermined threshold to determine whether the wind speed equals or exceeds the predetermined threshold, positioning a most windward solar tracker to a predetermined angle based on the comparison, and positioning a most leeward solar tracker to the predetermined angle based on the comparison. The solar trackers are positioned at the predetermined angles at predetermined intervals starting at the most windward solar tracker, and the remaining solar trackers remain in normal operating conditions.

[0008] In aspects, the determining comprises a ranked series of wind speeds. In other aspects, the predetermined angle comprises a ranked series of angles.

[0009] In some aspects, the predetermined threshold comprises a graded series of thresholds. In other aspects, the predetermined interval is every third solar tracker.

[0010] According to another aspect of the invention, a method of managing a dynamic response to wind in a solar tracker includes determining a wind speed, comparing the wind speed to a predetermined threshold to determine whether the wind speed equals or exceeds the predetermined threshold, and positioning first and second solar trackers to first and second predetermined angles based on the comparison.

[0011] In an aspect, the second predetermined angle is rotated at an angle opposite to the first predetermined angle.

[0012] In other aspects, the method further includes determining a position of the first solar tracker, determining a position of the second solar tracker, determining shading of the first and second solar trackers, communicating the positions of the first and second solar trackers, and positioning at least one of the first and second solar trackers based on the determined positions of adjacent solar trackers to reduce the shading.

[0013] In certain aspects, the communicating comprises wireless communications.

[0014] According to another aspect of the invention, a solar tracker system includes a solar tracker including a plurality of solar modules, each of the solar modules being spatially configured to face in a sun-facing position in a normal manner toward an incident direction of electromagnetic radiation originating from the sun. The solar module includes a tracker controller. The tracker controller includes: a processor; a memory having instructions stored thereon; a power supply configured to provide power to the tracker controller; and a motor controller. The tracker controller is configured to track the sun position. The tracker controller is configured to determine the wind speed. The processor compares the wind speed to a predetermined threshold to determine whether the wind speed equals or exceeds the predetermined threshold, and positions the most windward solar tracker to a predetermined angle based on the comparison. The solar trackers are positioned at the predetermined angle at predetermined intervals starting at the most windward solar tracker. The processor positions the most leeward solar tracker to the predetermined angle based on the comparison. The remaining solar trackers remain in normal operating conditions.

[0015] In aspects, the determining comprises a ranked series of wind speeds.

[0016] In other aspects, the predetermined angle comprises a graded series of angles.

[0017] In certain aspects, the predetermined threshold comprises a hierarchical series of thresholds.

[0018] In yet another aspect, the predetermined interval is every third solar tracker.

[0019] A further aspect of the invention relates to a method of managing a dynamic response to wind in a solar tracker, the method comprising determining a wind speed, comparing the wind speed to a predetermined threshold to determine whether the wind speed equals or exceeds the predetermined threshold, limiting a travel range of the solar tracker, determining whether the solar tracker is within the limited travel range, and when it is determined that the position of the solar tracker is outside the limited range, driving the solar tracker into the limited travel range. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various aspects of the present invention are described below with reference to the accompanying drawings, which are incorporated into and constitute a part of this specification, in which:

[0021] Figure 1 is a top perspective view of a solar tracking system provided in accordance with the present invention, the solar tracking system being configured to articulate the angle of a solar array to track the position of the sun;

[0022] Figure 2 yes Figure 1 Bottom perspective view of a solar tracking system;

[0023] Figure 3 yes Figure 1 An end view of a solar tracking system showing a solar array of the solar tracking system in a horizontal orientation;

[0024] Figure 4 yes Figure 1 A side view of a solar tracking system showing a solar array of the solar tracking system in an articulated orientation;

[0025] Figure 5 yes Figure 1 A side view of a field of solar tracking systems showing solar arrays of the solar tracking systems in a staged stowed arrangement;

[0026] Figure 6 yes Figure 1 A side view of a field of solar tracking systems showing the solar arrays of the solar tracking systems in a "W" stowed configuration;

[0027] Figure 7 Depicts the logic flow of a control algorithm according to the present invention.

[0028] Figure 8 Another logic flow of the control algorithm according to the present invention is depicted. DETAILED DESCRIPTION

[0029] The present invention relates to a solar tracking system and a method for articulating a solar tracking system to compensate for wind and wind load effects on the solar tracking system. Typically, a solar tracking system includes a solar array supported by a plurality of support beams. The plurality of support beams are in turn supported by a plurality of torque tubes. The plurality of torque tubes are coupled to an articulation system, which in turn is supported by a plurality of bases configured to be anchored to the ground or a fixed structure.

[0030] refer to Figures 1 to 5 A solar tracking system capable of tracking the position of the sun according to the present invention is illustrated and generally identified by reference numeral 10. The solar tracking system 10 includes a solar array 20, a plurality of support beams 30 ( Figure 3 ), a plurality of torque tubes 40 ( Figure 2 ), a plurality of bases 50 configured to rotatably support a plurality of torque tubes 40, and an articulation system 100 configured to rotate the plurality of torque tubes 40 and thus the solar array 20 relative to the base 50 ( Figure 1 ).

[0031] In one embodiment, as in Figure 1 , the solar panel 20 is decomposed into a first portion 20a and a second portion 20b, wherein the first and second portions 20a, 20b are spaced apart from each other along their lengths, thereby defining a gap 20c therebetween. A motor, such as an electric swing drive motor, may be positioned in the gap 20c. Additionally or alternatively, the drive motor may be positioned. Each of the first and second portions 20a, 20b is substantially similar, and therefore, for the sake of brevity, only the first portion 20a will be described in detail below. The first portion 20a of the solar array 20 includes a plurality of photovoltaic modules 22, each of which is mechanically and electrically coupled to each other, although it is contemplated that each (or a group of) photovoltaic modules 22 may be mechanically and / or electrically insulated from each other. In an embodiment, the photovoltaic module 22 may be any suitable photovoltaic module capable of generating electrical energy from sunlight, such as monocrystalline silicon, polycrystalline silicon, thin film, etc. The photovoltaic module 22 defines an upper surface 22a and an opposite, bottom surface 22b. As can be appreciated, the upper surface 22a of the photovoltaic module 22 includes photovoltaic cells (not shown), while the bottom surface 22b includes any suitable means for fixedly or selectively coupling the photovoltaic module 22 to the plurality of support beams 30, such as mechanical fasteners (e.g., bolts, nuts, etc.), adhesives, welds, etc. In an embodiment, the photovoltaic cells may be disposed on a suitable frame 22c ( Figure 3), the frame 22c includes suitable means for securing the photovoltaic module 22 to the plurality of support beams 30. In this manner, the frame 22c may include fastening means on its bottom surface, or a clamp or other suitable fastener (e.g., a Z-bracket, a C-clamp, an angle bracket, etc.) may be utilized to surround a portion of the frame 22c and selectively or fixedly couple the frame 22c to the plurality of support beams 30. Although generally illustrated as having a generally U-shaped profile, it is contemplated that the support beams 30 may include any suitable profile, such as square, rectangular, oval, etc. It is contemplated that the support beams 30 may be selectively or fixedly coupled to the torque tube 40 and / or the frame 22c of the photovoltaic module 22 using any suitable means, such as mechanical fasteners (e.g., bolts, clamps, etc.), adhesives, welding, etc. In one non-limiting embodiment, the support beams 30 are coupled to the torque tube using U-bolts or other similar fasteners.

[0032] Figure 3 A typical stowed position of a solar tracker is depicted. In this position, or 0° position, the photovoltaic modules 22 are substantially parallel to the ground. This has become the position that most solar tracker manufacturers recommend and specify that the solar tracker return to when the wind speed observed at approximately 3 meters above the ground reaches approximately 30 miles per hour (MPH).

[0033] It has been previously reported that Figure 3 The position of the solar tracker 10 in the 0° position represents the most favorable position to prevent damage to the solar tracker 10 by the wind. In addition, typically solar tracker arrangements (where there are multiple trackers 10 arranged in parallel north-south lines) are mechanically coupled to each other so that all solar trackers 10 move in unison as they track the path of the sun from east to west. Therefore, for most solar tracker installations, when wind speeds exceeding a certain threshold (e.g., 30 MPH) are observed, the entire field of trackers 10 moves to the 0° position. Even for some solar tracker 10 installations where the solar trackers are not mechanically coupled, the 0° position stowage strategy remains an industry standard. As a direct result, energy production from the solar tracker 10 is significantly reduced in windy conditions because the tracker is prevented from following the sun. But another result is that in this position, the solar tracker experiences turbulence, oscillations, and in fact, extreme stresses. In fact, the application has determined that this is actually one of the worst wind stowage positions for the solar tracker due to the alternating stresses applied to the tracker 10 when the wind flows over and under the photovoltaic module 22 in the 0° position.

[0034] One aspect of the present invention relates to an alternative stowed position. Figure 4 This alternative stowed position is depicted in Figure 4As seen in FIG, instead of the 0° position, the solar tracker 10 and its accompanying photovoltaic modules 22 are arranged facing the wind at a downward angle of about 30°. That is, the edge of the photovoltaic module 22 closest to the wind direction is tilted below the horizontal, about 30°. The result is a force acting on the tracker. Although described herein as about 30°, the present invention is not so limited, and any downward angle will produce some benefit in the experienced wind loads, however, downward angles greater than 30° have produced consistently greater benefits. The expected range of downward angles is 10 to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, 45 to 50, 50 to 55, and 55 to 60. However, the expected range is not intended to be limiting.

[0035] Even if the airflow over the tracker results in a steadier flow, resulting in less turbulence and oscillations, if the solar tracker 10 is mechanically linked, as is often the case, the resulting position will still result in a significant reduction in energy production. In practice, this is particularly exacerbated in instances where an easterly wind causes the solar tracker 10 to move in that direction, and in the afternoon, when the sun is to the west of its highest point. In this case, the solar tracker 10 will produce even less power than a tracker in the 0° position.

[0036] refer to Figure 5 Another aspect of the present invention relates to a staged stowage arrangement. In an exemplary staged stowage arrangement, the most windward (e.g., most easterly or most westerly) solar tracker 10 of a solar power plant 60 is placed in a 30° downward angle stowed position at a first detected wind speed (e.g., 30 MPH). This allows the most windward solar tracker 10 to act as a temporary wind shield for subsequent rows of solar trackers 10 and normalize the wind vector. In addition to the most easterly solar tracker 10, every third consecutive tracker 10 of the solar power plant 60 is also placed in a stowed position (e.g., 30° downward angle). Finally, the most leeward tracker 10 may also be placed in a stowed position. As will be appreciated, this can only be employed if each tracker 10 can be moved independently relative to the other trackers 10. This arrangement and mechanism of action are described in more detail in commonly assigned U.S. Patent No. 9,905,717, entitled Horizontal Balanced Solar Tracker, filed on December 9, 2012 and incorporated herein by reference.

[0037] With each tracker 10 driven independently, and capable of the staged stowage arrangement described above, a significant portion of all trackers 10 in the solar power plant 60 remain in normal operation, tracking the sun across the sky, and only a portion of the solar trackers 10 experience reduced energy production. A further aspect of the present invention is that instead of having a single wind speed threshold for stowing the solar trackers 10, a graded series of wind speeds may be used to move the trackers into the stowed position. In this case, a first portion of the solar trackers 10 may be placed in the stowed position at a predetermined wind speed (e.g., 30 MPH), and a second portion may be placed in the stowed position at a second predetermined wind speed (e.g., 40 MPH), and all solar trackers 10 may be placed in the stowed position at a third wind speed (e.g., 50 MPH). The number of stages, parameters, and rows of trackers 10 stowed may be adjusted depending on site specific information (e.g., prevailing wind direction, peak wind speed, etc.).

[0038] Figure 6 According to the present invention Figure 1 A side view of a field of solar tracking systems of FIG. 60 showing the solar arrays of the solar tracking systems in a "W" stowed arrangement. A further aspect of the invention relates to a W stowed arrangement of solar trackers 10. In the W arrangement, every other tracker 10 rotates in opposite directions. Thus, if the most windward tracker is rotated a 30° downward angle, the next tracker 10 will be rotated a 30° upward angle. The resulting turbulence of multiple ridges in this W arrangement throughout the solar power plant results in reduced forces affecting all solar trackers 10. The various eddies and backflows caused by this arrangement affect not only the airflow over trackers 10 deeper within the solar power plant, but also over those trackers 10 on the most windward side of the solar power plant 60. In addition, the resulting turbulence helps to reduce oscillations and prevent any single tracker from approaching any of its harmonics, which could be very detrimental to the tracker 10 and the power plant as a whole. Although described in conjunction with 30° downward and upward angles, other angles are contemplated within the scope of the invention.

[0039] In practice, when a threshold wind speed is observed, individual movable trackers 10 may be driven in appropriate directions to form a W shape. That is, each tracker 10 is driven in opposite directions of the trackers 10 on either side. As will be appreciated, due to the W stowed position, there is some risk of shading of adjacent trackers 10. Thus, one skilled in the art will appreciate that one or more of the trackers may be driven to a greater or lesser angle than its neighbors to avoid such shading, which may significantly reduce energy production.

[0040] refer to Figure 7, according to the present invention, the flowchart includes various blocks described in sequential order. However, those skilled in the art will appreciate that one or more blocks of the flowchart may be performed in a different order, repeated, and / or omitted without departing from the scope of the present invention. In addition, the following description of the flowchart refers to various actions or tasks performed by one or more controllers, but those skilled in the art will appreciate that in some examples, the controller performs the actions or tasks via one or more software applications, such as applications (which may be firmware) executed on the controller.

[0041] Figure 7 700 . Initially, at block 702, the controller determines the wind speed at the solar power plant 60. The wind speed may be determined, for example, by a wind speed sensor or by receiving this information via a network. The network may be wireless or wired. In an embodiment, the controller is configured to wirelessly (e.g., Zigbee, Wi-Fi, The controller may also communicate the wind speed to a wireless device or cloud for monitoring (eg, a wireless device, a cloud, or the like). It is contemplated that the signal may be communicated to a device having a display or dashboard for monitoring multiple solar trackers 10. The wind speed sensor may be integrated or remote. At box 704, the controller determines whether the wind speed equals or exceeds a predetermined threshold. The predetermined threshold may be, for example, 40 miles per hour. If the wind speed does not exceed this predetermined threshold ("No" at box 704), the controller continues to monitor the wind speed. If the wind speed does exceed the predetermined threshold ("Yes" at box 704), then at box 706, the controller positions the most windward solar tracker 10 to a predetermined angle based on this wind speed. For example, the predetermined angle may be a 30 degree downward angle.

[0042] At box 708, the most leeward solar tracker 10 is positioned at a predetermined angle. At box 710, the solar trackers 10 at predetermined intervals are positioned at predetermined angles. For example, the predetermined interval may be every third solar tracker 10 starting from the most windward solar tracker. For example, by bringing every third row to a high angle (such as 30 degrees), the remaining rows are shielded, thereby forming a "wind shield" intermittently throughout the rows. At box 712, the remaining solar trackers 10 are maintained in normal operating conditions. For example, this will allow the remaining solar trackers 10 to maximize energy production. For example, the two outer rows and every third inner row are positioned to be stowed at a predetermined 30 degree downward angle, and the remaining inner rows can operate normally or be stowed horizontally.

[0043] In another embodiment, two sets of parameters are used for the stow logic. A primary set of parameters that uses a first stow trigger speed on the most windward and leeward solar tracker 10 rows and rows at predetermined intervals. A secondary set of parameters that uses a second set of stow trigger speeds that is higher than the first stow trigger speed. For example, the primary parameters may stow at 30 mph, dwell for 15 minutes, and deploy at 20 mph. While the secondary parameters may stow at 33 mph, dwell for 15 minutes, and deploy at 23 mph. Thus, allowing the allowed tracking speeds on the inner rows to be increased and the number of stow hours to be reduced.

[0044] In another embodiment, the risk associated with higher secondary parameters may be monitored. For example, this may be calculated by analyzing motor current, amplitude and tracker performance during a wind event at the site.

[0045] A further aspect of the invention relates to another algorithm for controlling the positioning of the solar tracker 10. According to this aspect of the invention, the allowed range of travel is varied based on the measured wind speed. This system for controlling the maximum position of the tracker relative to the 0° position may be particularly useful for devices having a two-in-portrait (2P) photovoltaic module arrangement with photovoltaic modules 22 on the solar tracker 10. In one such arrangement, the photovoltaic modules 22 are arranged to have one photovoltaic module 22 on each side of the torque tube 40. As will be appreciated, the use of two photovoltaic modules 22 results in an increase in the overall height of the solar tracker 10, and therefore an increase in the torque on the solar tracker caused by wind loads compared to a one-in-portrait photovoltaic module arrangement. An example of this control algorithm for limiting the movement of the solar tracker 10 can be seen in Table 1.

[0046]

[0047]

[0048] Table 1

[0049] As can be seen with reference to Table 1, with measured wind speeds less than 25 MPH, the solar tracker 10 is allowed a total travel range of 100°, from negative 50° (where the solar tracker 10, and in particular the photovoltaic module 22, is pointing generally east) to positive 50° (where the photovoltaic module is facing generally west). The precise angular position of the photovoltaic module 22 relative to the 0° position at any given time is determined by the position of the sun and other observable conditions such as cloud cover, inter-tracker shading caused by altitude differences, and other factors known to those skilled in the art.

[0050] As shown in Table 1, as wind speed increases, the allowable travel range of the solar tracker 10, and in particular the allowable travel range of the photovoltaic module 22 relative to the 0° position, decreases. The travel range decreases with increasing wind speed until a threshold wind speed is observed. The tracker 10 can still follow its sun following or energy optimization control algorithm, but the distance the tracker 10 can be driven to reach these energy production optimized positions is limited. Once a maximum threshold is observed (45MPH in Table 1), the solar tracker 10 is driven to the stowed position. The stowed position may be selected to take advantage of the location of the array 20 and the prevailing wind direction or terrain of the region. As with other stowed positions for the solar tracker, the resulting energy production is reduced, however, the safety of the array 20 and photovoltaic module 22 is maintained here. In addition, by defining multiple travel ranges at various wind speeds, the penalties associated with limiting the travel range are minimized until a maximum threshold wind speed is observed.

[0051] Figure 8 Depicting a method that may be performed by a processor associated with a controller that causes a drive motor to position solar tracker 10. As will be apparent, Figure 8 The method described in can be operated continuously during the use of the array 20 to control the position of the solar tracker 10. After starting, the wind speed in the area of ​​the array 20 is determined at step 802. Once the wind speed is determined, a determination is made at step 804 whether the detected wind speed is greater than a predetermined threshold. If the answer is "no", the process returns to step 802. If the answer is "yes", then at step 806, the controller limits the travel range of the solar tracker 10 to a corresponding travel range based on the determined wind speed. In the case where the travel range of the tracker is limited, at step 808, the controller detects whether the tracker 10 is within the limited travel range. If the answer is "yes", then the process returns to step 802. If the answer is "no", then at step 810 the controller sends a signal to the drive motor to drive the solar tracker 10 to be within the limited travel range allowed by the wind speed. After the tracker 10 is driven into the limited travel range, the process returns to step 802. This can be done using, for example, an anemometer in electrical communication with the controller.

[0052] Although specific wind speed ranges are provided above, the present invention is not so limited, and the wind speed thresholds and limits on the allowed angular range of travel (tracking range) may be optimized for a given location without departing from the scope of the present invention.

[0053] Still further, it will be apparent to those skilled in the art that the solar tracker 10 is driven by a drive motor, such as a slewing drive motor or another drive motor. The drive motor is controlled by a controller, such as a microprocessor, which includes a processor capable of executing instructions that enable the controller to send and receive signals (including receiving signals from a wind speed detector, receiving signals for a solar tracker angular position detector), and send signals to the drive motor, thereby causing the drive motor to drive the solar tracker to a desired position while taking into account wind speed and sun position, among other factors.

[0054] Although several embodiments of the present invention have been shown in the drawings, the present invention is not intended to be limited thereto, as the present invention is intended to be as broad in scope as the art will allow, and the specification is intended to be read as such. Any combination of the above embodiments is also contemplated and is within the scope of the appended claims. Therefore, the above description should not be interpreted as limiting, but merely as an example of a particular embodiment. A person skilled in the art will envision other modifications within the scope of the appended claims.

Claims

1. A method of managing dynamic response to wind in a solar tracker array, the method comprising: Determine wind speed; comparing the wind speed with a predetermined threshold to determine whether the wind speed equals or exceeds the predetermined threshold; and positioning a first solar tracker in the array to a first predetermined angle and a second solar tracker in the array to a second predetermined angle based on the comparison, Wherein when the determined wind speed exceeds the predetermined threshold, a solar tracker between the first solar tracker and the second solar tracker remains in a normal operating condition. 2 . The method of claim 1 , wherein to achieve the second predetermined angle, the second solar tracker is rotated in an opposite direction to the first solar tracker.

3. The method according to claim 1, wherein the method further comprises: determining a position of the first solar tracker; determining a position of the second solar tracker; determining shading of the first solar tracker and the second solar tracker; communicating the positions of the first solar tracker and the second solar tracker; and At least one of the first solar tracker and the second solar tracker is repositioned based on the determined shading. The method of claim 1 , wherein the communicating comprises wireless communication.

5. A method of managing dynamic response to wind in a solar tracker array, the method comprising: Determine wind speed; comparing the wind speed to a predetermined threshold to determine whether the wind speed equals or exceeds the predetermined threshold; limiting the travel range of the solar tracker array; determining whether the solar tracker array is within the restricted travel range; and When it is determined that the position of the solar tracker array is outside the restricted travel range, the solar tracker array is driven into the restricted travel range.

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