Boost and regulation groups for wind power plant

A method, control arrangement, and wind power plant (WPP) comprising a plurality of wind turbine generators (WTGs) are disclosed. The method includes operating, responsive to a received power demand corresponding to the WPP, a boost group of one or more WTGs of the plurality of WTGs to begin producing a boosted power output, wherein the boosted power output of each of the one or more WTGs of the boost group is regulated independent of the power demand. The method further includes determining, based on a measured amount of boosted power production, power production set points for a regulation group of one or more different WTGs of the plurality of WTGs to thereby meet the power demand.

BACKGROUND

Field of the Invention

Embodiments presented in this disclosure generally relate to power generation using boost and regulation groups of wind turbine generators.

Description of the Related Art

Modern power generation and distribution networks increasingly rely on renewable energy sources, such as wind turbine generators. In some cases, the wind turbine generators may be substituted for conventional, fossil fuel-based generators. Beyond merely generating and delivering electrical power, the wind turbine generators are responsible for contributing to grid stability through frequency regulation. However, natural variations in wind conditions can affect the ability of wind turbines to predictably deliver power and regulate grid frequency. Additionally, wind conditions at times may be unsuitable for generating power.

SUMMARY

One embodiment of the present disclosure is a method, a control arrangement, and a wind power plant (WPP) comprising a plurality of wind turbine generators (WTGs). The method includes operating, responsive to a received power demand corresponding to the WPP, a boost group of one or more WTGs of the plurality of WTGs to begin producing a boosted power output. The method further includes determining, based on a measured amount of boosted power production, power production set points for a regulation group of one or more different WTGs of the plurality of WTGs to thereby meet the power demand.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Wind turbine generators (WTGs) of a wind power plant (WPP) may at times produce active power in amounts larger than the power available through the wind, “boosting” the power level using the kinetic energy stored in the rotor during operation. Because the grid frequency may change somewhat unpredictably during a frequency event, it is beneficial to provide an adaptive and responsive power output (including a boosted power output) for grid stabilization purposes. While it is possible to configure the WTG control system to provide a tight regulation of boost power production, this regulation capability adds significant and sometimes unwanted complexity to the control system. Additionally, managing the structural loads on components of the WTGs during boosting may impose operational constraints that are prohibitively expensive to design around, making the tight regulation of boost power production unsuitable or undesired.

Embodiments of the disclosure are generally directed to a control arrangement and associated method of controlling a power output of a wind power plant. The method includes operating a boost group of one or more WTGs to begin producing a boosted power output, and determining, based on the amount of boost power production from the boost group, power production set points for a regulation group of one or more other WTGs to meet a power demand for the WPP.

In some embodiments, the boosted power output is regulated independent of any changes to the power demand during a boosting event, e.g., during a grid disturbance. In some cases, WTGs of the boost group are operated without a substantially continuous control of the boost power output. As discussed herein, “without substantially continuous control” refers to controlling the boost power output with a lesser time resolution (e.g., updating less frequently) than that of the corresponding wind-based power output of the WTGs. For example, instead of providing and updating boost power set points for the WTG periodically during a boosting event, and adjusting the boost power output based on the set points, the boost group in some cases provides a “one-shot” boosting, in which WTGs provide a predetermined level of boost power in response to an instruction to begin boosting. One-shot boosting can be beneficial to obtain the most boost power possible from the boost group, and for the relatively simplicity of the control system. In some embodiments, the predetermined level of boost power corresponds to full boosting capabilities of the WTGs. In other embodiments, the predetermined level of boost power is based on the properties of the demand signal (amplitude, length, etc.).

In another example, during a boosting event the boost power output control is periodically updated with a frequency that is less than the update frequency of the wind-based power output control. For example, during a boosting event the wind-based power set points may be updated with a frequency that is twice the update frequency of the boost power set points (a 2:1 ratio). Other suitable rational or non-rational numbers are possible, such as 3:1, 3:2, 4:1, 4:3, 5:1, 10:1, etc.

As boost capabilities may vary between WTGs and based on current operational conditions, the collective boost power output from the wind power plant may be somewhat uncontrolled. The one or more other WTGs included in the regulation group are operated in a manner to mitigate some of the effects of boost power production by the boost group WTGs. In some embodiments, the WTGs of the regulation group are operated with a curtailed power output, which provides additional regulation headroom for mitigating effects of boost power production. The boost group WTGs form a relatively slow, outer control loop for the wind power plant while the regulation group WTGs form a relatively fast, inner control loop that is responsive to the outer control loop.

In some embodiments, the control arrangement can instruct the WTGs to halt the boost power output during a boost event. Halting the boost power may be performed responsive to determining that boost power is no longer needed, e.g., caused by changes in the grid condition, improved wind conditions providing greater wind power production capability, etc. Halting the boost power output before the boost capability of each WTG is fully expended offers the advantage of a shorter recovery period to resume normal operation and restore boost capability of the WTGs.

In some embodiments, a boost quality of the WTGs is assessed and the number of WTGs to include in the regulation group is determined based on the relative boost quality. In some embodiments, the particular WTGs of the WPP may be selected for the boost group and/or the regulation group based on the corresponding boost quality. Boost quality may be assessed based on simulated or actual operation boost production data for the WTGs.

FIG. 1illustrates a diagrammatic view of a horizontal-axis wind turbine100. The wind turbine100typically includes a tower102and a nacelle104located at the top of the tower102. A wind turbine rotor106may be connected with the nacelle104through a low speed shaft extending out of the nacelle104. As shown, the wind turbine rotor106includes three rotor blades108mounted on a common hub110, but may include any suitable number of blades, such as one, two, four, five, or more blades. The blade108(or airfoil) typically has an aerodynamic shape with a leading edge112for facing into the wind, a trailing edge114at the opposite end of a chord for the blade108, a tip116, and a root118for attaching to the hub110in any suitable manner.

For some embodiments, the blades108may be connected to the hub110using pitch bearings120such that each blade108may be rotated around its longitudinal axis to adjust the blade's pitch. The pitch angle of a blade108may be controlled by linear actuators or stepper motors, for example, connected between the hub110and the blade108. Blade pitch control may also be used among other systems to maximize the power generated below rated wind speeds and to reduce the power generated above the rated wind speed to prevent excessive loading on turbine components, e.g., the generator and gearbox. Although the following embodiments are described in the context of wind turbine generators, the embodiments are not limited to such. Indeed, this disclosure may apply to any power generation system capable of providing temporary boosts to power output using the kinetic energy of components such as generator rotors.

FIG. 2illustrates a wind power plant operatively connected with an electrical grid, according to one embodiment. In the depicted arrangement200, a wind power plant205includes a plurality of wind turbines100operatively connected with an electrical grid210at a point of common coupling (or PCC)215. In some embodiments, the wind turbines100of the wind power plant205are coupled with a substation230that includes a wind power plant controller235. In this case, the output from the substation230is coupled with electrical grid210, and the electrical power generated by the wind turbines100is carried on one or more connections240to the substation230. In an alternate embodiment, the wind power plant controller is located at an alternate location within the arrangement200, such as with one of the wind turbines100. In an alternate embodiment, one or more wind turbines100may deliver electrical power directly to the electrical grid210without being grouped and/or directed through the substation230. The wind power plant controller235is communicatively coupled with each of the wind turbines100(e.g., with a respective wind turbine-level controller245) through one or more connections250.

The electrical grid210represents any suitable electrical transmission and/or distribution grids, which may be operated at one or more voltages. The electrical grid210generally includes a number of transmission lines, transformers, substations, etc. The electrical grid210may be connected with one or more other generation facilities220, such as one or more additional wind power plants, and/or one or more different types of generation facilities, such as fossil fuel-based, geothermal, solar, hydroelectric, nuclear, and so forth. The electrical grid210is also connected with one or more loads225, which generally represent industrial, commercial, and/or residential electricity consumers.

Generally, differences in the amount of electrical power generated (e.g., produced by the wind power plant205and by the other generation facilities220) and the amount of electrical power demanded by loads (e.g., loads225) on an electrical grid cause the grid frequency to deviate from its prescribed or nominal value. Typical values of nominal grid frequency are 60 hertz (Hz) in the US and 50 Hz in Europe. One example of grid frequency deviation occurs when power demand exceeds the power generated—the difference in power can be drawn from the kinetic energy of the wind turbine generator, causing the wind turbine rotor (e.g., rotor106ofFIG. 1) to slow down and the grid frequency to decrease accordingly. Conversely, when power generation exceeds the amount of power demand, the grid frequency may increase. In some cases, the wind turbine generators may be configured to operate within a predetermined frequency range, such as ±1% of the nominal grid frequency, before disconnecting or performing other regulation procedures to restore the grid frequency to within the predetermined frequency range.

Each wind turbine100includes a wind turbine generator (not shown) configured to convert the mechanical energy of the wind turbine rotor106into one or more phases of electrical power, which is ultimately delivered to the electrical grid210and the loads225connected thereto. In various embodiments, the wind turbine generators produce electrical power based on control signals provided by the wind power plant controller235and/or wind turbine generator controllers245. The wind turbine generators may also provide feedback signals and other information to the wind power plant controller235using the connections240,250.

FIG. 3is a block diagram illustrating a control arrangement for a wind power plant comprising a plurality of wind turbine generators, according to one embodiment. The control arrangement300is generally disposed at the wind power plant205(FIG. 2), and may be distributed among one or more wind turbines and/or a substation. The wind power plant (WPP) controller235is communicatively coupled with a plurality of wind turbine generator (WTG) controllers2451-N. Each of the WTG controllers2451-N(generically or collectively, “controller(s)245”) is coupled with one or more corresponding wind turbine generators that are configured to supply electrical power to an associated electrical grid. While the control arrangement300is depicted as having a distributed control implementation, an alternative implementation may consolidate all of the functionality of the control arrangement300into a single controller.

The WPP controller235includes a processor305and memory310. Each of the WTG controllers245may include a processor385and memory390. The processors305,385may have any suitable form, such as a general purpose microprocessor, a controller, an application-specific integrated circuit (ASIC), and so forth. In some embodiments, the processors305,385comprises parts of (or all of) one or more integrated circuits (ICs) and/or other circuitry components. In some embodiments, the processors305,385also comprise electronically-readable instructions, such as firmware code, software code, and the like. In some embodiments, components comprising the processor305or385are located together, such as being included in a common printed circuit board. Processors305,385are further coupled with the respective memories310,390. Memories310,390may include a variety of computer-readable media selected for their size, relative performance, or other capabilities: volatile and/or non-volatile media, removable and/or non-removable media, etc. Memories310,390may include registers, cache, random access memory (RAM), storage, etc. Storage included as part of memories310,390may typically provide a non-volatile memory for the processors305,385, and may include one or more different storage elements such as Flash memory, a hard disk drive, a solid state drive, an optical storage device, and/or a magnetic storage device.

Although not explicitly shown, the processors305,385and memories310,390are further coupled with input/output (I/O) circuitry, which may include a number of different I/O adapters including circuitry that supports communication to and from the controllers235,245. One non-limiting example of I/O circuitry includes network interface cards (NICs) for communicating through the connections250(FIG. 2). Other I/O adapters included in the control arrangement300may generally support an end-user's interface with the controllers235,245. For example, the I/O circuitry may include connections for visual/audio/other sensory output devices, as well as connections for input devices such as a keyboard, mouse, touchscreen, etc. In one embodiment, I/O circuitry may include graphics cards that include separate processing elements and/or memory.

The controllers235,245may include one or more modules that provide a particular functionality within the control arrangement300. The modules may be embodied in hardware or firmware (e.g., included in or coupled with processors305,385), as software stored in memories310,390, or combinations thereof. Furthermore, the modules may be implemented solely within one of the controllers235,245and/or distributed across different controllers. Although modules are depicted as being included within a particular controller of the controllers235,245, in other embodiments one or more modules may be included in other controller(s).

The wind power plant controller235includes a power production control module315(or “power production module,” “power module”), a boost power production control module320(or “boost power production module,” “boost module”), an assessment module325, and a grouping module335.

The power module315operates to generate set points317or other suitable demand signals for controlling the power produced by each of the WTGs in the WPP. The set points317correspond to available power production for the WTGs based on current wind conditions. The power module315generates the set points317based on a received or generated WPP-level power demand signal, such as a WPP power output set point, according to any suitable techniques.

The boost module320operates to control boost power production from each of the WTGs. As referred to herein, “boost power” production refers to power production by the WTGs using the kinetic energy (or inertia) available in the rotors of the WTGs during their operation. The boost module320controls boost power production of the WTGs based on the power demand signal at the WPP level. For example, the WPP controller235may determine that producing the amount of power indicated by the WPP power demand signal requires an amount of boost power beyond available power in the wind.

In some embodiments, the boost module320transmits instruction signals322to certain ones of the WTG controllers245to begin producing boost power. In some embodiments, some or all of the WTG controllers245are configured to regulate the boost power production of the corresponding WTG independent of a power demand signal. In some embodiments, the WTG controllers245produce boost power without tracking a boost power reference signal. For example, the instruction signals322might not include boost power reference values. In another example, the instruction signals322could indicate that the WTG controller245should begin producing boost power at a predetermined level or rate, such as at a maximum rate, or some other level or rate known to the WTG controller245(e.g., according to value(s) stored in memory390).

In other embodiments, a boost power reference signal is provided to the WTG controllers245but values of the reference signal are updated relatively slowly. In such a case, the WTG controller245may be unable to substantially continuously track the boost power reference signal, as the boost characteristics of the WTG includes power production variations that occur more quickly (e.g., with a greater time resolution) than the boost power reference values are updated.

While it may be possible to control the boost power production based on (and responsive to) the power demand signal, such a feature introduces a significant amount of complexity to the control arrangement300. Due to the additional stresses on the WTG caused by providing a boosted power output, suitable operational margins can be significantly limited during boost power production. For example, when rotor speed decreases and power increases, the corresponding torque values may increase and reach predetermined torque limits. Thus, the power output level could be limited from its full boosting potential due to structural considerations. Thus, the process of developing operational parameters that are suitable for desired power production and managing the wind turbine structural loads, all while losing one of the control parameters may be prohibitively costly, or it may be entirely infeasible.

The grouping module335operates to determine a boost group345and regulation group350of the WTGs of the WPP. In some embodiments, each WTG included in the WPP is assigned or designated by the grouping module335to one of the boost group345and the regulation group350. In other embodiments, at least one of the WTGs of the WPP is not included in either the boost group345and the regulation group350. The grouping module335determines a current configuration340(or composition) of the WPP, which may be updated periodically or responsive to certain events or triggers. The grouping module335may also include a default configuration355that is applied to the WPP under certain conditions. Generally, by operating the WTGs within separate boost group345and regulation group350, a greater power output range of the WPP can be dynamically controlled.

The groupings (boost group345and regulation group350) may be determined based on boost production data360included in the memory310. The boost production data360reflects a realistic, time-based boost power production profile for the WTGs, including variations in the boost signal. The boost production data360may be simulated boost production data365for a WTG with a particular configuration, or may reflect operational boost production data370reflecting production of the particular WTG acquired through measurements. The operational data370may include historical data375relating to one or more previous boost events using the WTG, and/or current data380relating to performance during a current boost event.

In some embodiments, the assessment module325processes the boost production data360for various WTGs to calculate corresponding boost quality values330. The boost quality values330may be calculated based on any number of different criteria that reflect the ability of a particular WTG to provide a desired boost power response. The boost quality values330may be determined based on a boost power reference signal, and may include criteria such as an amplitude of overshoot/undershoot of a reference signal level, a difference signal based on a comparison with the reference signal, a slope value for increase or decrease, etc. Each WTG may correspond to one or more boost quality values330, for example, a respective value for each calculated aspect. In another example, a single boost quality value330is calculated for each WTG based on a sum (or weighted sum) reflecting some or all of the calculated aspects.

The boost quality values330are used by the grouping module335to determine the configuration (or composition) of boost group345and regulation group350. In some embodiments, the boost quality values330of some or all of the WTGs may be used to calculate a number of WTGs to include in the regulation group350. Generally, including fewer WTGs in the regulation group350allows for the wind power plant to have a greater boosting power capability, as more WTGs are included in the boost group345. It may be beneficial, therefore, to determine a minimum number of WTGs to include in the regulation group350. However, if the boost quality of the WTGs is sufficiently low (as determined by the respective boost quality values330), an additional regulation capability may be necessary to mitigate the poor boosting quality and ensure that the overall WPP power demand is met. Determining an insufficient boosting quality may be based on, e.g., an average of the boost quality values330of all the WTGs, an average of the boost quality values330of a predetermined number of WTGs having the relative highest boost quality values330, whether a predetermined number of WTGs meets a threshold boost quality value, or any other suitable measure.

In some embodiments, the particular WTGs that are included in the boost group345are selected based on the relative boost quality values330, when compared with other WTGs of the WPP. For example, say the grouping module335determines that three WTGs (of ten WTGs included in the WPP) will be included in the regulation group350, based collectively on the boost quality values330of all ten WTGs. The grouping module335may then select the seven WTGs having the highest boost quality values330for the boost group345, leaving the three WTGs with the lowest boost quality values330to the regulation group350. In other embodiments, selection of the WTGs for the boost group345and/or regulation group350may be according to any suitable technique, such as at random, based on location within the WPP and/or measured wind conditions, and so forth.

In some embodiments, the composition of boost group345and regulation group350may be updated based on an analysis of boost production data360for the boost group245. More specifically, the current boost production data380(i.e., reflecting the actual boost performance of the boost group during the current boost event) may be collected and analyzed to determine whether the regulation group350provides sufficient regulation to meet the power demand and/or excessive regulation. Alternatively, measured power production from the WPP or set point data for the regulation group350may be analyzed to determine whether the regulation group350provides sufficient and/or excessive regulation. As discussed above, it may generally be beneficial to minimize the number of WTGs in the regulation group350to provide an increased boost capability for the WPP. Altering the composition of the boost group345and regulation group350generally includes transitioning one or more WTGs of the WPP to or from the boost group345or regulation group350.

Updating or altering the composition of the boost group345and the regulation group350may be periodic and/or event-driven. For example, the grouping module335could update the composition of the groups each time it is determined that boost production will be required to meet a power demand for the wind power plant. In another example, the grouping module335periodically analyzes the measured power production using a particular composition, comparing the measured power production with historical production data from alternate composition(s). In this way, the grouping module335may update the groups' composition based on the “whole” power production of the WPP in addition to (or as an alternative to) analysis of boost power production.

FIG. 4is a block diagram illustrating exemplary operation of a control arrangement for a wind power plant comprising a plurality of wind turbine generators, according to one embodiment. Generally, arrangement400represents one possible configuration of the control arrangement300with a wind power plant205.

As shown, the WPP includes four WTGs100A,1006,100C,100D. The power control module315receives a power demand signal415. The power demand signal415may be received from an external source, such as by a controller outside of the wind power plant that is also coupled with the electrical grid210. Alternatively, the demand signal415may be generated internally to the wind power plant, for example according to predetermined, contracted amounts of power output and/or frequency regulation. The predetermined amounts may be stored in or otherwise accessible by the WPP controller.

Based on the power demand signal415, the power control module315generates and transmits set points317A,317B (or other suitable demand signals) to WTG100C,100D. Although not shown, the power control module315also transmits set points to the WTGs100A,100B. The set points represent power production targets for the WTGs that are based on the available wind power. Responsive to the received set points (e.g.,317A,317B), the WTGs100A-100D produce power outputs425A-425D to the electrical grid210. Based on information provided by a measurement unit435coupled with the electrical grid210, the power control module315determines whether boosted power is required to meet the power demand signal415. In some embodiments, the measurement unit435may couple with current and/or voltage sensors connected with the electrical grid210. In some embodiments, measurement unit435additionally or alternatively couples with one or more sensors for measuring wind conditions, such as an anemometer for wind speed. Based on the measured power production and/or a determined value of available power (based on measured wind conditions), the power control module315determines that boost power output should be provided by one or more WTGs to meet the power demand415.

As shown, WTGs100A,100B are selected for the boost group345and WTGs100C,100D are selected for the reference group350. The selection of WTGs for boost group345and/or reference group350may be based on relative boost quality values, as discussed above. The power control module315transmits a signal420to the boost control module320. In one embodiment, the signal420may be a boost power demand signal. In another embodiment, the signal420may be an instruction to trigger boost power production according to the determined boost group435. The boost control module320transmits instruction signals322A,322B to WTG100A,100B to begin producing boost power outputs430A,430B to the electrical grid210. In one embodiment, the instruction signals322A,322B represent one-shot boost instructions (i.e., open-loop control). Alternatively, the instruction signals322A,322B may represent a boost power reference signal that is updated relatively slowly (compared with changes in the boost response profile of the WTG). Alternatively, the instruction signals322A,322B may be substantially continuous boost power reference signals that are not followed or tracked closely by the WTG100A,100B.

The boost power outputs430A,430B are injected into electrical grid210. However, as the boost power production is not continuously regulated, the WTGs100C,100D of the regulation group350are operated responsive to the boost power production in order to augment the boost power and to thereby meet the power demand specified by the power demand signal415.

In some embodiments, the WTGs100C,100D of regulation group350are operated in a curtailed state, in which WTGs100C,100D each produce a power output that is less than what is available from the wind power. The power control module315may cause the WTGs100C,100D to enter the curtailed state in response to determining the boost group345and regulation group350. The curtailed power output may correspond to a predetermined amount, for example, 90% of the available power at the WTG. Accordingly, the WTGs100C,100D of regulation group350each have a 10% margin up to the available power output to augment the boost power production of WTGs100A,100B. In some embodiments, the set points317A,317B for the WTGs100C,100D are set within the margin formed by the curtailment in order to mitigate some of the variations of the boost power production. For example, say the power control module315determines, based on information from the measurement unit435, that the power production for the WPP is not being met, due to variations in the boost power production. The power control module315in response alters the set points317A,317B for WTGs100C,100D of the regulation group350to mitigate the difference. In this way, the injection of boost power outputs430A,430B using the boost control module320forms an outer control loop (outer loop)410providing relatively slower control, and the regulation group350forms an inner control loop (inner loop)405providing relatively faster control, and being responsive to the outer loop410.

FIG. 5is a plot illustrating wind power plant control using boost and regulation groups of WTGs, according to one embodiment. Generally, plot500represents one possible operation of the control arrangement300.

A boost power demand signal505is depicted, which can be representative of a requested boost power demand corresponding to one or multiple WTGs of the wind power plant. In one example, the boost power demand signal505is generated by the WPP controller, and the WPP controller instructs one or more WTGs to begin boosting based on the boost power demand signal505. In another example, the WPP controller transmits the boost power demand signal505to a particular WTG controller. In another example, the boost power demand signal505is received by the WPP controller, and the WPP controller instructs one or more WTGs to begin boosting based on the boost power demand signal505. The power production signal510reflects the power production of one or more WTGs included in the boost group. The power production signal510is generally responsive to the boost power demand signal505, which may include one or more intermediate steps, such as a WTG controller receiving an instruction to begin one-shot boosting power production. The power production signal515reflects a power output from one or more WTGs in a regulation group. The different signals505,510,515are not drawn to scale but are to be interpreted in view of the discussion provided herein.

At time t0, the boost power demand signal505has a zero value, indicating that no boost power has been requested or required. Between times t0and t1, the power production signal510varies around a power set point value PSP, which may reflect relatively minor changes in available power and other operational conditions. The power production signal515reflects operation of the regulation group at a curtailed power level (according to curtailed power signal Pcurt525), which is some predetermined amount less than the available power in the wind (available power signal Pavail520). For example, the curtailed power signal525may represent a fixed amount or percentage less than the available power520. The curtailed power signal525may be determined based on historical boost data. For example, the curtailment for the regulation group need not be as severe for cases where the boost quality of WTGs in the boost group is relatively good (e.g., the change in power production signal510appears similar to the boost power demand signal505). While the WTGs of the regulation group (corresponding to power production signal515) are depicted as operating with a curtailed power output prior to the boosting event (i.e., between times t0and t1, in other embodiments the WTGs are operated with a non-curtailed power output prior to the boosting event. For example, in some cases the composition of the regulation group is not determined until the boost power demand signal505is received, such that the WTGs to be allocated to the boost group and regulation group would be operated “normally”—with a non-curtailed power output—prior to the boosting event.

At time t1, the boost power demand signal505rises to a level Pboostreflecting a request for the specified boost power level during the time period t1-t4. The boost power demand signal505may be specified in any suitable form, such as units of power (e.g., kilowatts (kW)), a percentage of the WTG rated power, etc. In response, WTGs included in the boost group are instructed to begin producing boost power output. Accordingly, power production signal510rises from near set point level PSPat time t1to approximately a PSP+Pboostlevel at time t2. During its rise, the power production signal510may overshoot the desired level (time t2) before decreasing below the desired level (between times t2and t3). At time t3, the power production signal510reaches a plateau at a level less than the PSP+Pboostlevel and remains relatively steady until time t4.

At time t4, the boost power demand signal505is reduced to a zero boost level. The decrease in boost demand may reflect an instruction received by the WTGs of the boost group to stop producing boost power (e.g., a command to abort boosting). Alternatively, the WTGs of the boost group may be configured to produce boost power as long as possible, e.g., ceasing boost power production when the rotor speed decreases to a predetermined minimum rotor speed value. The power production signal510decreases sharply between times t4and t5, as the WTGs of the boost group recover from providing the boost power. Generally, during a recovery, some of the power produced by the WTGs from the available wind power is used to increase and restore the kinetic energy of the rotor to a pre-boosting level. After the sharp decrease of power production to time t5, the power production signal510may include a slow increase to the power output. During a first portion of the recovery period between times t5and t6, the rotor speed is stabilized, and during a second portion of the recovery period between times t6and t7, the rotor speed is returned to a pre-boosting level. The power production signal510stabilizes near the original PSPlevel at approximately time t8.

Ideally, the boost power demand signal505would be matched exactly by the boost power curve of signal510. However, the boost power production provided by a real, operational WTG may vary from the boost power demand signal505, including periods of overshoot and/or undershoot of the boosting demand level. These effects are especially pronounced for the case of one-shot boosting, which after “firing” the shot is not subsequently closely controlled relative to the boosting demand level.

In some embodiments, the WTGs of the reference group are used to augment the boost power production to more closely meet the boost power demand. The power production signal515of the reference group WTGs follows the curtailed power signal Pcurt525and begins gradually rising between times t2and t3. The rise may result from increased power production set points that are responsive to the decrease of power production signal510beneath the PSP+Pboostlevel, and/or based on historical or simulated boost data indicating an expected shape, trend, profile, etc. of the power production signal510. In some embodiments, the increased power production set points for the regulation group mitigate (or offset) the difference between power production signal510and the PSP+Pboostlevel, whether partly or fully.

In some cases, the power production from WTGs of the regulation group may also be used to increase wind power plant output during the recovery periods of the boost group WTGs, mitigating some of the power deficit as those WTGs recover. In some cases, the power production from the regulation group may be used to recover the WTGs of the boost group, resulting in a shorter recovery period.

FIG. 6includes plots illustrating an increased range of dynamic control of the wind power plant using boost and regulation groups of WTGs, according to one embodiment. In plot600, no regulation group is provided for the wind power plant (i.e., all WTGs in the WPP can be used for boosted power output). The wind power plant controller is thus able to regulate the power output of the WPP from a minimum level (e.g., corresponding to minimum technical output levels of each of WTGs, such as 20% of the rated power output) up to the power available from the wind Pavail. This dynamic control range is represented by shaded area605. In the case of one-shot or other types of not-closely regulated boost power production, without a separate regulation group, the WPP is able to produce power up to a PBOOST ALLlevel, but is unable closely regulate the output corresponding to area610.

In plot615, one or more WTGs are included in the regulation group and are not available for providing a boosted power output. While each WTG included in the regulation group reduces a maximum amount of production of the wind power plant based on boosting to PBOOST+REG, providing one or more WTGs for the regulation group allows for an increased range of dynamic control of the WPP. The area610, which was unable to be closely regulated in plot600, is partly overlapped by shaded area620. Area620depicts the additional controllable power range that is enabled by use of the regulation group WTG(s). The unregulated range is correspondingly reduced to a lesser area625.

FIG. 7illustrates a method of controlling a power output of a wind power plant comprising a plurality of wind turbine generators, according to one embodiment. Method700begins at an optional block705, an assessment module of a control arrangement calculates boost quality value(s) for one or more WTGs based on simulated boost production data or historical boost production data. At optional block715, a grouping module of the control arrangement determines the composition of the boost group and the regulation group of WTGs. In some alternate embodiments, a default configuration is provided defining the composition of the groups.

At block720, the WTGs of the regulation group are operated at respective curtailed power output levels. The curtailed power level may be predetermined, such as a particular amount or percentage less than the amount of available power in the wind.

At block725, the WTGs of the boost group are operated to begin producing a boosted power output. This operation is responsive to a received or generated power demand corresponding to the WPP. The operation may include transmitting an instruction to the WTGs to begin boosted power output, in some cases without providing a specific boost power set point for the WTGs to track.

At block730, the current boost production data is analyzed for the boost group of WTGs. Alternatively, the set points of the regulation group WTGs or measured power production may be analyzed. The analysis generally determines whether the regulation group provides sufficient regulation to meet the power demand and/or provides excessive regulation. Depending on the result, method700may proceed along path732to block735, where the composition of the boost group and/or the regulation group is altered if the regulation is insufficient or excessive. However, if the composition of groups does not need to be altered, method700proceeds along path734to block720to continue operation. Following the completion of block735, the method may proceed along path738and continue operation at block720, or may proceed along path736and end.

As will be appreciated by one skilled in the art, the embodiments disclosed herein may be embodied as a system, method, or computer program product. Accordingly, aspects may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Aspects of the present disclosure are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments presented in this disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.