Abstract:
Embodiments of the invention are generally related to optimizing performance of a wind power plant. A controller may be configured to sequentially, for each wind turbine in a wind power plant, adjust the power production by a predefined amount, and determine whether the adjustment of power production from the wind turbine results in an increase in overall power production from the wind farm. Adjustments in power production of the wind turbines may be continuously made so that power production of the wind power plant approaches the maximum possible value.

Description:
FIELD OF THE INVENTION 
       [0001]    Embodiments of the invention generally relate to wind turbine farms, and more specifically to improving the performance of wind turbine farms. 
       BACKGROUND 
       [0002]    In recent years, there has been an increased focus on reducing emissions of greenhouse gases generated by burning fossil fuels. One solution for reducing greenhouse gas emissions is developing renewable sources of energy. Particularly, energy derived from the wind has proven to be an environmentally safe and reliable source of energy, which can reduce dependence on fossil fuels. 
         [0003]    Energy in wind can be captured by a wind turbine, which is a rotating machine that converts the kinetic energy of the wind into mechanical energy, and the mechanical energy subsequently into electrical power. Common horizontal-axis wind turbines include a tower, a nacelle located at the apex of the tower, and a rotor that is supported in the nacelle by means of a shaft. The shaft couples the rotor either directly or indirectly with a rotor assembly of a generator housed inside the nacelle. A plurality of wind turbines generators may be arranged together in a wind farm/park or wind power plant to generate sufficient energy to support a grid. 
         [0004]    In general each turbine in a wind farm is configured to extract maximum possible energy from the wind. When wind turbines are lined up one behind another in relation to the wind direction, it is likely that the first turbine will extract the maximum possible energy from the wind. The remaining turbines behind the first turbine will extract relatively less power because they are in the wake of the first turbine. 
       SUMMARY OF THE INVENTION 
       [0005]    Embodiments of the invention generally relate to wind turbine farms, and more specifically to improving the performance of wind turbine farms. 
         [0006]    One embodiment of the invention provides a method for a method for optimizing power production in a wind farm comprising, sequentially for each turbine in the wind farm:
       (a) adjusting the power production from a wind turbine by a predefined amount;   (b) determining whether the adjustment of power production from the wind turbine results in an increase in overall power production from the wind farm;       
 
         [0009]    (c) upon determining that the overall power production has increased, continuously repeating steps (a)-(b) until an increase in power production is not detected; and
       (d) upon determining that the overall power production has not increased, selecting a next turbine for optimization.       
 
         [0011]    Another embodiment of the invention provides a wind power plant, comprising a wind farm comprising a plurality of wind turbines; and a controller configured to optimize performance of the wind power plant by, sequentially for each turbine in the wind farm:
       (a) adjusting the power production from a wind turbine by a predefined amount;   (b) determining whether the adjustment of power production from the wind turbine results in an increase in overall power production from the wind farm;   (c) upon determining that the overall power production has increased, continuously repeating steps (a)-(b) until an increase in power production is not detected; and   (d) upon determining that the overall power production has not increased, selecting a next turbine for optimization.       
 
         [0016]    Yet another embodiment of the invention provides a controller for optimizing performance of a wind power plant, wherein the controller is configured to sequentially for each turbine in the wind farm:
       (a) adjust the power production from a wind turbine by a predefined amount;   (b) determine whether the adjustment of power production from the wind turbine results in an increase in overall power production from the wind farm;   (c) upon determining that the overall power production has increased, continuously repeat steps (a)-(b) until an increase in power production is not detected; and   (d) upon determining that the overall power production has not increased, select a next turbine for optimization.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Embodiments of the present invention are explained, by way of example, and with reference to the accompanying drawings. It is to be noted that the appended drawings illustrate only examples of embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0022]      FIG. 1  illustrates an exemplary wind turbine according to an embodiment of the invention. 
           [0023]      FIG. 2  illustrates an exemplary wind turbine nacelle according to an embodiment of the invention. 
           [0024]      FIG. 3  illustrates an exemplary wind power plant control system according to an embodiment of the invention. 
           [0025]      FIG. 4  is a flow diagram of exemplary operations to optimize wind power plant performance according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    In the following, reference is made to embodiments of the invention. However, it should be understood that the invention is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the invention. 
         [0027]    Furthermore, in various embodiments the invention provides numerous advantages over the prior art. However, although embodiments of the invention may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the invention. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s). 
         [0028]    The following is a detailed description of embodiments of the invention depicted in the accompanying drawings. The embodiments are examples and are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
         [0029]      FIG. 1  illustrates an exemplary wind turbine  100  according to an embodiment of the invention. As illustrated in  FIG. 1 , the wind turbine  100  includes a tower  110 , a nacelle  120 , and a rotor  130 . In one embodiment of the invention, the wind turbine  100  may be an onshore wind turbine. However, embodiments of the invention are not limited only to onshore wind turbines. In alternative embodiments, the wind turbine  100  may be an off shore wind turbine located over a water body such as, for example, a lake, an ocean, or the like. 
         [0030]    The tower  110  of wind turbine  100  may be configured to raise the nacelle  120  and the rotor  130  to a height where strong, less turbulent, and generally unobstructed flow of air may be received by the rotor  130 . The height of the tower  110  may be any reasonable height. The tower  110  may be made from any type of material, for example, steel, concrete, or the like. In some embodiments the tower  110  may be made from a monolithic material. However, in alternative embodiments, the tower  110  may include a plurality of sections, for example, two or more tubular steel sections  111  and  112 , as illustrated in  FIG. 1 . In some embodiments of the invention, the tower  110  may be a lattice tower. Accordingly, the tower  110  may include welded steel profiles. 
         [0031]    The rotor  130  may include a rotor hub (hereinafter referred to simply as the “hub”)  131  and at least one blade  132  (three such blades  132  are shown in  FIG. 1 ). The rotor hub  131  may be configured to couple the at least one blade  132  to a shaft (not shown). In one embodiment, the blades  132  may have an aerodynamic profile such that, at predefined wind speeds, the blades  132  experience lift, thereby causing the blades to radially rotate around the hub. The nacelle  120  may include one or more components configured to convert aero-mechanical energy of the blades to rotational energy of the shaft, and the rotational energy of the shaft into electrical energy. 
         [0032]    The wind turbine  100  may include a plurality of sensors for monitoring a plurality of parameters associated with, for example, environmental conditions, wind turbine loads, performance metrics, and the like. For example, a strain gauge  133  is shown on the blade  132 . In one embodiment, the strain gauge  133  may be configured to detect bending and or twisting of the blades  132 . The information regarding bending and twisting of the blades may be necessary to perform one or more operations that reduce the loads on the blades  132  that may occur, for example, during high wind gusts. In such situations, the blades may be pitched to reduce the loads, thereby preventing damage to the blades. 
         [0033]      FIG. 1  also illustrates an accelerometer  113  that may be placed on the tower  110 . The accelerometer  113  may be configured to detect horizontal movements and bending of the tower  110  that may be caused due to the loads on the wind turbine  100 . The data captured by the accelerometer  113  may be used to perform one or more operations for reducing loads on the wind turbine  100 . In some embodiments of the invention, the accelerometer  113  may be placed on the nacelle  120 . 
         [0034]      FIG. 1  also depicts a wind sensor  123 . Wind sensor  123  may be configured to detect a direction of the wind at or near the wind turbine  100 . By detecting the direction of the wind, the wind sensor  123  may provide useful data that may determine operations to yaw the wind turbine  100  into the wind. The wind sensor  123  may use the speed and direction of the wind to control blade pitch angle. Wind speed data may be used to determine an appropriate pitch angle that allows the blades  132  to capture a desired amount of energy from the wind or to avoid excessive loads on turbine components. In some embodiments, the wind sensor  123  may be integrated with a temperature sensor, pressure sensor, and the like, which may provide additional data regarding the environment surrounding the wind turbine. Such data may be used to determine one or more operational parameters of the wind turbine to facilitate capturing of a desired amount of energy by the wind turbine  100  or to avoid damage to components of the wind turbine. 
         [0035]    In one embodiment of the invention, a light detection and ranging (LIDAR) device  180  may be provided on or near the wind turbine  100 . For example, the LIDAR  180  may be placed on a nacelle, hub, and/or tower of the wind turbine, as illustrated in  FIG. 1 . In alternative embodiments, the LIDAR  180  may be placed in one or more blades  132  of the wind turbine  100 . In some other embodiments, the LIDAR device may be placed near the wind turbine  100 , for example, on the ground as shown in  FIG. 1 . In general, the LIDAR  180  may be configured to detect wind speed and/or direction at one or more points in front of the wind turbine  100 . In other words, the LIDAR  180  may allow the wind turbine to detect wind speed before the wind actually reaches the wind turbine. This may allow wind turbine  100  to proactively adjust one or more of blade pitch angle, yaw position, and like operational parameters to capture greater energy from the wind, and reduce loads on turbine components. In some embodiments, a controller may be configured to combine the data received from a LIDAR device  180  and the wind sensor  123  to generate a more accurate measure of wind speed and/or direction. 
         [0036]    While a strain gauge  133 , accelerometer  113 , and wind sensor  123  are described herein, embodiments of the invention are not limited to the aforementioned types of sensors. In general, any type and number of sensors may be placed at various locations of the wind turbine  100  to facilitate capturing data regarding structural health, performance, damage prevention, acoustics, and the like. For example, a pitch angle sensor may be placed at or near a wind turbine blade to determine a current pitch angle of the blade. 
         [0037]      FIG. 2  illustrates a diagrammatic view of typical components internal to the nacelle  120  and tower  110  of a wind turbine generator  100 . When the wind  200  pushes on the blades  132 , the rotor  130  spins, thereby rotating a low-speed shaft  202 . Gears in a gearbox  204  mechanically convert the low rotational speed of the low-speed shaft  202  into a relatively high rotational speed of a high-speed shaft  208  suitable for generating electricity using a generator  206 . In an alternative embodiment, the gear box may be omitted, and a single shaft, e.g., the shaft  202  may be directly coupled with the generator  206 . 
         [0038]    A turbine controller  210  may sense the rotational speed of one or both of the shafts  202 ,  208 . If the controller decides that the shaft(s) are rotating too fast, the controller may signal a braking system  212  to slow the rotation of the shafts, which slows the rotation of the rotor  106 , in turn. The braking system  212  may prevent damage to the components of the wind turbine generator  100 . The turbine controller  210  may also receive inputs from an anemometer  214  (providing wind speed) and/or a wind vane  216  (providing wind direction). Based on information received, the controller  210  may send a control signal to one or more of the blades  108  in an effort to adjust the pitch  218  of the blades. By adjusting the pitch  218  of the blades with respect to the wind direction, the rotational speed of the rotor (and therefore, the shafts  202 ,  208 ) may be increased or decreased. Based on the wind direction, for example, the controller  210  may send a control signal to an assembly comprising a yaw motor  220  and a yaw drive  222  to rotate the nacelle  104  with respect to the tower  102 , such that the rotor  106  may be positioned to face more (or, in certain circumstances, less) upwind. 
         [0039]    The generator  206  may be configured to generate a three phase alternating current based on one or more grid requirements. In one embodiment, the generator  206  may be a synchronous generator. Synchronous generators may be configured to operate at a constant speed, and may be directly connected to the grid. In some embodiments, the generator  206  may be a permanent magnet generator. In alternative embodiments, the generator  206  may be an asynchronous generator, also sometimes known as an induction generator. Induction generators may or may not be directly connected to the grid. For example, in some embodiments, the generator  206  may be coupled to the grid via one or more electrical devices configured to, for example, adjust current, voltage, and other electrical parameters to conform with one or more grid requirements. Exemplary electrical devices include, for example, inverters, converters, resistors, switches, transformers, and the like. 
         [0040]    Embodiments of the invention are not limited to any particular type of generator or arrangement of the generator and one or more electrical devices associated with the generator in relation to the electrical grid. Any suitable type of generator including (but not limited to) induction generators, permanent magnet generators, synchronous generators, or the like, configured to generate electricity according to grid requirements falls within the purview of the invention. 
         [0041]      FIG. 3  illustrates an exemplary wind power plant  300  according to an embodiment of the invention. As illustrated, the wind power plant  300  may include a wind farm  310  coupled with a grid  340 , a park controller  330 , and a Supervisory Control And Data Acquisition (SCADA) system  320 . The wind farm  310  may include one or more wind turbines, such as the representative wind turbine  100 . The wind turbines collectively act as a generating plant ultimately interconnected by transmission lines with a power grid  340 , which may be a three-phase power grid. The plurality of turbines of wind farm  310  may be gathered together at a common location in order to take advantage of the economies of scale that decrease per unit cost with increasing output. It is understood by a person having ordinary skill in the art that the wind farm  310  may include an arbitrary number of wind turbines of given capacity in accordance with a targeted power output. 
         [0042]    The power grid  340  generally consists of a network of power stations, transmission circuits, and substations coupled by a network of transmission lines. The power stations generate electrical power by nuclear, hydroelectric, natural gas, or coal fired means, or with another type of renewable energy like solar and geothermal. Additional wind farms analogous to the wind farm  310  depicted may also be coupled with the power grid  340 . Power grids and wind farms typically generate and transmit power using Alternating Current (AC). 
         [0043]    The controller  330  can be implemented using one or more processors  331  selected from microprocessors, micro-controllers, digital signal processors, microcomputers, central processing units, field programmable gate arrays, programmable logic devices, state machines, logic circuits, analog circuits, digital circuits, and/or any other devices that manipulate signals (analog and/or digital) based on operational instructions that are stored in a memory  334 . In one embodiment of the invention, the controller  330  may be configured to generate a power reference signals to each of the wind turbines in the wind farm  310 . Based on the power reference signals  311  the wind turbines in the wind farm  310  may adjust one or more operational parameters, e.g., blade pitch angles, so that the wind farm produces a desired amount of power. 
         [0044]    Memory  334  may be a single memory device or a plurality of memory devices including but not limited to read-only memory (ROM), random access memory (RAM), volatile memory, non-volatile memory, static random access memory (SRAM), dynamic random access memory (DRAM), flash memory, cache memory, and/or any other device capable of storing digital information. 
         [0045]    Mass storage device  333  may be a single mass storage device or a plurality of mass storage devices including but not limited to hard drives, optical drives, tape drives, non-volatile solid state devices and/or any other device capable of storing digital information. An Input/Output (I/O) interface  331  may employ a suitable communication protocol for communicating with the wind turbines of wind farm  310 . 
         [0046]    Processor  332  operates under the control of an operating system, and executes or otherwise relies upon computer program code embodied in various computer software applications, components, programs, objects, modules, data structures, etc. to read data from and write instructions to one or more wind turbines of wind farm  310  through I/O interface  331 , whether implemented as part of the operating system or as a specific application. 
         [0047]    A human machine interface (HMI)  350  is operatively coupled to the processor  332  of the controller  330  in a known manner. The HMI  350  may include output devices, such as alphanumeric displays, a touch screen, and other visual indicators, and input devices and controls, such as an alphanumeric keyboard, a pointing device, keypads, pushbuttons, control knobs, etc., capable of accepting commands or input from the operator and transmitting the entered input to the processor  332 . 
         [0048]    As stated above, if a plurality of wind turbines are lined up one behind another in relation to the wind direction, the first turbine in the row may be capable of producing the highest amount of power because it received the full force of the wind. The remaining turbines may be in the wind shadow, or wake, of the first turbine. Because the first turbine extracts energy from the wind, the remaining turbines may not be able to produce as much power as the first turbine because they may experience lower wind speeds. This loss in ability to produce the maximum amount of power is commonly referred to as a wake loss. 
         [0049]    In general, most turbines are configured to extract as much power from the wind as may be possible. However, in the aforementioned example, the first turbine may generate the greatest amount of power during its lifetime. This also means that the components of the first turbine are likely to undergo greater wear and tear, and that the remaining turbines may be under-utilized. Accordingly, it may be advantageous to reduce the power production from the first turbine to allow greater use and production from the remaining turbines in a row. Embodiments of the invention propose methods for managing the production of power from each turbine in a wind park so that the maximum amount of energy can be generated by the wind park as a whole. 
         [0050]    In one embodiment, the model  336  may be used to determine the specific power reference (and therefore power production) from each turbine in a wind park. However, predefined models tend to be fraught with errors. Embodiments of the invention provide dynamic methods for determining the most desirable power references for each turbine in a wind park based on actual conditions and production. 
         [0051]    In one embodiment, the park controller may be configured to execute a control algorithm configured to determine the optimal power reference signals for each wind turbine in the wind farm  310 . In a particular embodiment, the control algorithm may implement an iterative process of adjusting the power reference for each turbine in a wind farm until the optimal power reference for each turbine is found. As an example, assume that there are a total of N turbines in a wind farm. To determine the optimum power reference the each of the N turbines, the controller implementing the control algorithm may implement the process illustrated in  FIG. 4 . 
         [0052]    As illustrated in  FIG. 4 , the process may begin in step  410  by selecting one of the turbines in the wind farm by setting the value of i to 1, wherein i is a turbine identifier ranging from 1 to N. In step  420 , the power of the selected turbine (P i ) is adjusted down by a value A. The value A may be any reasonable amount, for example, 10 kilowatts. Then, in step  430 , the controller may determine whether there is an improvement in power production from the wind farm. If there is an improvement in production, this may indicate that further improvement may be possible by reducing power production from the selected turbine. Therefore, the process may move to step  420  if an improvement in power production is detected in step  430 . 
         [0053]    If there no improvement in power production is detected in step  430 , the controller may go to step  440 , wherein the power may be adjusted upwards by a value A. Thereafter, in step  450 , the controller may determine whether there is in improvement in power production from the wind farm. If there is an improvement in production, this may indicate that further improvement may be possible by increasing power production from the selected turbine. Therefore, the process may move to step  440  if an improvement in power production is detected in step  450 . 
         [0054]    If no improvement in power production is detected in step  450 , this may indicate that no further improvement in power production of the wind farm is possible by adjusting the power production from the selected wind turbine any further. Accordingly, the controller may go to step  455  where the wind turbine power is reduced by A to return to the previously calculated power value which was deemed to be the maximum power production value. Thereafter, in step  460 , i may be incremented by 1 to select a new turbine. In step  470 , the controller may determine whether the incremented value of i is greater than N. If yes, the controller goes to step  410  where i is set again to 1. On the other i is not determined to be greater than N in step  470 , the controller goes to step  420  to repeat the iterative process for the newly selected turbine. 
         [0055]    By executing the algorithm outlined in  FIG. 4 , over time, the power references for the turbines in the wind farm will approach the most optimum levels, thereby improving performance of the wind farm. 
         [0056]    While the method steps in  FIG. 4  are described with reference to plant controller  330 , in alternative embodiments, any controller in the wind power plant may be configured to perform one or more of the steps shown in  FIG. 4 . For example, in one embodiment, the steps shown in  FIG. 4  may be performed by a wind turbine controller in a power plant where the wind turbines are connected to each other via a network for sharing data and control signals. In some embodiments, some of the method steps of  FIG. 4  may be performed by a plant controller while other steps may be performed by the turbine controller. For example, in one embodiment, steps  420 - 450  may be performed by a turbine controller, while steps  410 ,  460 , and  470  may be performed by a plant controller. 
         [0057]    By providing methods that improve the performance of wind turbines in a wind park through an iterative probine process, embodiments of the invention obviate the need for wind farm performance enhancing models which can be erroneous in predicting the optimum power settings for the wind turbines in the wind park. 
         [0058]    While the invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.