System and method for controlling low speed operation of a wind turbine

Abstract

A system and method for controlling low speed operation of a wind turbine electrically coupled to a power grid is provided. The wind turbine includes a generator and a power converter. The generator includes a generator rotor and a generator stator. An operating parameter of the generator rotor is indicative of low speed operation of the generator. Accordingly, a crossing of the operating parameter to a first threshold is detected. In response, at least a portion of a required reactive power generation amount is generated via the generator rotor. This portion is then delivered to the power grid via a grid side of the power converter.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to wind turbines, and more particularly to systems and methods for controlling a wind turbine during low speed operation. BACKGROUND

[0002] Wind power is considered one of the cleanest, most environmentally friendly energy sources available, and wind turbines have been receiving increased attention in this regard. Modern wind turbines typically include a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The nacelle includes a rotor assembly coupled to the gearbox and the generator. The rotor assembly and the gearbox are mounted on a bedplate support frame located within the nacelle. The one or more rotor blades capture the kinetic energy of wind using known airfoil principles. The rotor blades transfer the kinetic energy in the form of rotational energy to a shaft, which couples the rotor blades to the gearbox, or directly to the generator if no gearbox is used. The generator then converts the mechanical energy into electrical energy, and the electrical energy can be transmitted to a transformer and / or a power converter housed within the tower and then deployed to a power grid. Modern wind power systems typically take the form of a wind farm having a plurality of such wind turbine generators operable to supply power to a transmission system that provides power to a power grid.

[0003] Some wind turbine configurations include a doubly-fed induction generator (DFIG). Whenever a DFIG is employed to generate the output of a wind turbine, slip can be encountered. Generally, slip can be the difference between the operating speed and the synchronous speed of the DFIG (divided by the synchronous speed). The operating speed is typically the rotational speed of the generator rotor, and the synchronous speed is typically the rotational speed of the magnetic field of the generator stator. The synchronous speed can correspond to the operating frequency of the power grid.

[0004] A reduction in the speed of the generator rotor (e.g., in response to a reduction in wind speed) can result in an increase in slip. The increase in slip, in turn, can result in an increase in the generator rotor voltage. Thus, during low wind speed operation, a DFIG can operate with a high degree of slip and a corresponding high rotor voltage. Operating under such conditions can reduce the expected life cycle of various components of the power system of the wind turbine and / or result in a reduction in the operational envelope of the wind turbine.

[0005] Accordingly, there is a continuing need in the art for new and improved systems and methods that address the aforementioned problems. With this in mind, the present disclosure is directed to systems and methods for controlling low speed operation of a wind turbine. SUMMARY

[0006] Aspects and advantages of the application will be set forth in part in the following description, or can be obvious from the description, or can be learned through practice of the application.

[0007] In one aspect, the present disclosure is directed to a method for controlling low speed operation of a wind turbine electrically coupled to a power grid. The wind turbine can include a generator and a power converter. The generator can have a generator rotor and a generator stator. The method can include detecting, via a controller, a crossing of a first threshold value by an operating parameter of the generator rotor. The operating parameter can be indicative of low speed operation of the generator. In response to the operating parameter crossing the first threshold value, the method can include generating, via the generator rotor, at least a portion of a required reactive power production amount. Additionally, the method can include delivering, via a grid side of the power converter, the portion of the required reactive power production amount to the power grid.

[0008] In embodiments, generating the portion of the required reactive power production amount can include receiving, via the controller, a reactive current setpoint for the generator. The reactive current setpoint can correspond to a current of the generator rotor that contributes to meeting the required reactive power production amount via the generator stator. Additionally, the method can include generating, via the controller, a modified reactive current setpoint configured to contribute to generating the portion of the required reactive power production amount via the generator rotor. Moreover, the method can include changing at least one operating state of the converter based on the modified reactive current setpoint.

[0009] In further embodiments, the portion of the required reactive power production amount can be a first reactive power portion of the required reactive power production amount. Additionally, changing the operating state(s) of the converter can contribute to meeting the required reactive power production amount via a reactive power output of the wind turbine. The reactive power output can include the first reactive power portion delivered to the power grid via the grid side of the power converter and a second reactive power portion delivered to the power grid via a bypass of the power converter.

[0010] In another embodiment, changing the operating state(s) of the converter can contribute to meeting the required reactive power production amount in its entirety by the portion of the required reactive power production amount delivered to the power grid via the grid side of the power converter.

[0011] In yet another embodiment, the operating parameter of the generator rotor can be a generator rotor voltage magnitude. Additionally, the first threshold value can be a generator rotor voltage threshold magnitude indicative of low speed operation of the generator. Moreover, detecting the operating parameter of the generator rotor approaching the first threshold value can include receiving, via the controller, data indicative of the generator rotor voltage magnitude.

[0012] In embodiments, receiving data indicative of a generator rotor voltage magnitude can include determining, via the controller, a converter modulation index of a rotor-side converter of the power converter indicative of the generator rotor voltage magnitude.

[0013] In further embodiments, receiving data indicative of a generator rotor voltage magnitude can include determining, via the controller, a DC link voltage of a DC link of the power converter indicative of the generator rotor voltage magnitude.

[0014] In another embodiment, the operating parameter of the generator rotor can be a generator rotor rotational speed. Additionally, the first threshold can be a generator rotor rotational speed threshold. Moreover, when the generator rotor rotational speed is at or below the generator rotor rotational speed threshold, low speed operation of the generator can be indicated.

[0015] In yet another embodiment, delivering the portion of the required reactive power generation to the power grid via the grid-side of the power converter can facilitate a reduction in the generator rotor voltage magnitude.

[0016] In embodiments, the reduction in the generator rotor voltage magnitude can facilitate a reduction in a thermal load and / or an electrical load across components of the power converter.

[0017] In further embodiments, after the portion of the required reactive power generation is delivered to the power grid via the grid-side of the power converter, the method can further include detecting, via the controller, a crossing of a second threshold by an operating parameter of the generator rotor. The method can further include, in response to the operating parameter approaching the second threshold, reducing, via the controller, an active power setpoint and / or a reactive power setpoint of the generator.

[0018] In another embodiment, the second threshold can be based on a predicted reliability of at least one component of the power converter.

[0019] In yet another embodiment, the wind turbine can further include a rotor having one or more rotor blades mounted thereto. The rotor can be rotatably coupled to the generator. Additionally, reducing the active power setpoint and / or the reactive power setpoint of the generator can facilitate an increase in an inertia of the rotor of the wind turbine.

[0020] In another aspect, the disclosure is directed to a system for controlling a wind turbine coupled to a power grid. The wind turbine can include a generator and a power converter. The generator can include a generator rotor and a generator stator. The system can include a controller communicatively coupled to the generator. The controller can include at least one processor configured to perform a plurality of operations. The plurality of operations can include any of the operations and / or features described herein.

[0021] CLAIM 1. A method for controlling low speed operation of a wind turbine electrically coupled to a power grid, the wind turbine having a generator and a power converter, the generator having a generator rotor and a generator stator, the method comprising:

[0022] detecting, via a controller, a crossing of a first threshold value by an operating parameter of the generator rotor, the operating parameter indicative of low speed operation of the generator;

[0023] generating, via the generator rotor, at least a portion of a required reactive power generation quantity in response to the operating parameter crossing the first threshold value; and

[0024] delivering, via a grid side of the power converter, the portion of the required reactive power generation quantity to the power grid.

[0025] CLAIM 2. The method of claim 1, wherein generating the portion of the required reactive power generation quantity comprises:

[0026] receiving, via the controller, a reactive current setpoint for the generator, the reactive current setpoint corresponding to a current of the generator rotor that contributes to meeting the required reactive power generation quantity via the generator stator;

[0027] generating, via the controller, a modified reactive current setpoint configured to contribute to generating the portion of the required reactive power generation quantity via the generator rotor; and

[0028] changing at least one operating state of the power converter based on the modified reactive current setpoint.

[0029] CLAIM 3. The method of claim 2, wherein the portion of the required reactive power generation quantity comprises a first reactive power portion of the required reactive power generation quantity, and wherein changing the at least one operating state of the power converter contributes to meeting the required reactive power generation quantity via a reactive power output of the wind turbine, the reactive power output comprising the first reactive power portion delivered to the power grid via the grid side of the power converter and a second reactive power portion delivered to the power grid via a bypass of the power converter.

[0030] CLAIM 4. The method of claim 2, wherein changing the at least one operating state of the power converter contributes to meeting all of the required reactive power generation quantity by the portion of the required reactive power generation quantity delivered to the power grid via the grid side of the power converter.

[0031] CLAIM 5. The method of claim 1, wherein the operating parameter of the generator rotor comprises a generator rotor voltage magnitude, wherein the first threshold comprises a generator rotor voltage threshold magnitude indicative of the low speed operation of the generator, and wherein detecting the crossing of the first threshold further comprises:

[0032] receiving, via the controller, data indicative of the generator rotor voltage magnitude.

[0033] CLAIM 6. The method of claim 5, wherein receiving data indicative of the generator rotor voltage magnitude further comprises:

[0034] determining, via the controller, a converter modulation index of a rotor side converter of the power converter indicative of the generator rotor voltage magnitude.

[0035] CLAIM 7. The method of claim 5, wherein receiving data indicative of the generator rotor voltage magnitude further comprises:

[0036] determining, via the controller, a DC link voltage of a DC link of the power converter indicative of the generator rotor voltage magnitude.

[0037] CLAIM 8. The method of claim 1, wherein the operating parameter of the generator rotor comprises a generator rotor rotational speed, wherein the first threshold comprises a generator rotor rotational speed threshold, and wherein the low speed operation of the generator is indicated when the generator rotor rotational speed is at or below the generator rotor rotational speed threshold.

[0038] CLAIM 9. The method of claim 1, wherein delivering the portion of the required reactive power generation to the power grid via the grid side of the power converter facilitates a reduction in a generator rotor voltage magnitude.

[0039] CLAIM 10. The method of claim 9, wherein the reduction in the generator rotor voltage magnitude facilitates a reduction in at least one of a thermal load and an electrical load across components of the power converter.

[0040] CLAIM 11. The method of claim 1, further comprising:

[0041] detecting, via the controller, a crossing of a second threshold by the operating parameter of the generator rotor after the portion of the required reactive power generation is delivered to the power grid via the grid side of the power converter; and

[0042] in response to the crossing of the second threshold by the operating parameter, reducing, via the controller, at least one of an active power setpoint and a reactive power setpoint of the generator.

[0043] Technical Solution 12. The method of Technical Solution 11, wherein the second threshold is based on a predicted reliability of at least one component of the power converter.

[0044] Technical Solution 13. The method of Technical Solution 11, wherein the wind turbine further comprises a rotor rotatably coupled to the generator, the rotor having one or more rotor blades mounted to the rotor, and wherein reducing at least one of the active power setpoint and the reactive power setpoint of the generator facilitates an increase in an inertia aspect of the rotor of the wind turbine.

[0045] Technical Solution 14. A system for controlling a wind turbine coupled to an electric power grid, the wind turbine having a generator and a power converter, the generator having a generator rotor and a generator stator, the system comprising a controller communicatively coupled to the generator, the controller comprising at least one processor configured to perform a plurality of operations, the plurality of operations comprising:

[0046] detecting a crossing of a first threshold by an operating parameter of the generator rotor, the operating parameter indicative of a low speed operation of the generator;

[0047] in response to the operating parameter crossing the first threshold, generating, via the generator rotor, at least a portion of a required reactive power production;

[0048] delivering, via a grid side of the power converter, the portion of the required reactive power production to the electric power grid.

[0049] Technical Solution 15. The system of Technical Solution 14, wherein generating the portion of the required reactive power production comprises:

[0050] receiving a reactive current setpoint for the generator, the reactive current setpoint corresponding to a current of the generator rotor, the current facilitating satisfaction of the required reactive power production via the generator stator;

[0051] generating a modified reactive current setpoint, the modified reactive current setpoint configured to facilitate generation of the portion of the required reactive power production via the generator rotor; and

[0052] changing at least one operating state of the power converter based on the modified reactive current setpoint.

[0053] CLAIM 16. The system of claim 15, wherein the portion of the required reactive power production includes a first reactive power portion of the required reactive power production, and wherein changing the at least one operating state of the power converter facilitates meeting the required reactive power production via a reactive power output of the wind turbine, the reactive power output including the first reactive power portion delivered to the power grid via the grid-side of the power converter and a second reactive power portion delivered to the power grid via a bypass of the power converter.

[0054] CLAIM 17. The system of claim 14, wherein the operating parameter of the generator rotor includes a generator rotor voltage magnitude, wherein the first threshold includes a generator rotor voltage threshold magnitude indicative of the low speed operation of the generator, and wherein detecting the crossing of the first threshold further comprises:

[0055] receiving data indicative of the generator rotor voltage magnitude.

[0056] CLAIM 18. The system of claim 14, wherein the operating parameter of the generator rotor includes a generator rotor rotational speed, wherein the first threshold includes a generator rotor rotational speed threshold, and wherein the low speed operation of the generator is indicated when the generator rotor rotational speed is at or below the generator rotor rotational speed threshold.

[0057] CLAIM 19. The system of claim 14, wherein delivering the portion of the required reactive power production to the power grid via the grid-side of the power converter facilitates reducing a generator rotor voltage magnitude, wherein the reduction in the generator rotor voltage magnitude facilitates reducing at least one of a thermal load and an electrical load across components of the power converter.

[0058] CLAIM 20. The system of claim 14, wherein the plurality of operations further comprise:

[0059] detecting a crossing of a second threshold by the operating parameter of the generator rotor after the portion of the required reactive power production is delivered to the power grid via the grid-side of the power converter; and

[0060] in response to the operating parameter approaching the second threshold, reducing at least one of an active power setpoint and a reactive power setpoint of the generator.

[0061] These and other features, aspects, and advantages of the present application will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and serve to explain the principles of the application. BRIEF DESCRIPTION OF DRAWINGS

[0062] A complete and enabling disclosure of the application, including its best mode, directed to one of ordinary skill in the art follows in the description of the specification in reference to the drawings wherein:

[0063] Figure 1 a perspective view illustrating one embodiment of a wind turbine in accordance with the present disclosure;

[0064] Figure 2 a schematic diagram illustrating one embodiment of an electrical power system for use with a wind turbine in accordance with the present disclosure;

[0065] Figure 3 a block diagram illustrating one embodiment of a controller for use with a wind turbine in accordance with the present disclosure;

[0066] Figure 4 a flowchart illustrating one embodiment of control logic for a system for controlling a wind turbine in accordance with the present disclosure; and

[0067] Figure 5 a graphical plot illustrating the relationship between generator rotor speed and generator rotor voltage in accordance with the present disclosure.

[0068] Repetition of reference characters in the present specification and drawings is intended to represent the same or similar features or elements. DETAILED DESCRIPTION

[0069] Reference will now be made in detail to embodiments of the application, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the application and is not meant as a limitation of the application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the scope or spirit of the application. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present application covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0070] As used herein, the terms "first," "second," and "third" can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0071] The terms“coupled,”“fixed,”“attached to” and the like, mean both directly and indirectly coupled, fixed, or attached as appropriate, unless otherwise specified herein.

[0072] As used herein throughout the description and claims, approximate language is used to modify any quantitative representation that is permissible to vary, without altering the basic function to which it is related. Thus, a value modified by one or more terms such as“about,”“approximately,” and“substantially” is not limited to the precise value specified. In at least some instances, the approximate language can correspond to the precision of an instrument used to measure the value, or the precision of a method or machine used to construct or manufacture the component and / or system. For example, the approximate language can refer to within a 10% margin.

[0073] Here, as well as throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein, unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and endpoints are independently combinable with other endpoints to modify the range.

[0074] Generally, the present disclosure is directed to systems and methods for controlling low speed operation of a wind turbine. Low speed operation can be encountered when environmental conditions acting on the wind turbine result in a relatively low rotational speed of the wind turbine rotor and the rotatably connected generator rotor. For example, low speed operation can include any operation of the wind turbine that results in a rotational speed of the generator rotor of less than or equal to 1100 revolutions per minute (RPM) when coupled to a 50 Hz power grid. When coupled to a 60 Hz power grid, low speed operation can be encountered when the rotational speed of the generator rotor is less than or equal to 900 RPM.

[0075] For wind turbines equipped with a DFIG, the rotational speed of the magnetic field of the generator stator can correspond to the operating frequency of the power grid (e.g., 50 or 60 Hz). However, the rotational speed of the generator rotor can depend on environmental conditions and / or control settings of the wind turbine. Thus, as the wind speed decreases and the generator rotor slows, the slip of the generator can increase. To maintain operation of the DFIG, the increase in slip can require an increase in the generator rotor voltage. The increase in the generator rotor voltage can result in an increase in the load across various components of the power converter of the wind turbine, and thus can result in an increase in wear of the components.

[0076] Additionally, at any time when the power generation is greater than the minimum power threshold, the grid authority can levy a reactive power generation demand equal to the full rated reactive power capability of the wind turbine. In other words, the grid authority can require the full rated reactive power capability of the wind turbine regardless of whether the environmental conditions support the minimum power generation or the maximum power generation. This reactive power generation demand is typically satisfied via reactive power delivered through the generator stator directly to the power grid through the transformer of the wind turbine. This additional generation demand can result in further increases in the generator rotor voltage, even during low speed operation. As such, the systems and methods disclosed herein can help satisfy the reactive power generation demand without increasing the rotor voltage. In fact, use of the systems and methods disclosed herein can result in a reduction in the rotor voltage at a given generator rotor speed relative to the rotor voltage that can be achievable without use of the systems and methods.

[0077] To reduce the rotor voltage and, thus, the load across the various components of the power converter, the systems disclosed herein can detect when an operating parameter of the generator rotor crosses (e.g., depending on the nature of the operating parameter, "exceeds" or "falls below") a first threshold indicative of low speed operation of the generator. In response to detection of low speed operation, the system can modify at least one set point of the converter so as to satisfy at least a portion of the required reactive power generation via reactive power generated through the generator rotor rather than the generator stator. This portion of the required reactive power generation can then be delivered to the power grid via the grid side of the power converter.

[0078] By delivering at least a portion of the reactive power generation demand via the grid side of the power converter, the rotor voltage and corresponding load(s) across the various components of the power converter can be reduced. As a result, the operating envelope of the wind turbine can be expanded such that power can continue to be generated at lower wind speeds without undue damage to the components of the wind turbine.

[0079] It should be appreciated that use of the systems and methods disclosed herein can reduce the flow of reactive power through the generator so as to reduce the rotor voltage. This, in turn, can improve converter reliability when operating in the low speed region of the wind turbine operating envelope. Additionally, reducing the rotor voltage can also allow the converter to operate over a lower speed range, which can translate into increased power production of the wind turbine.

[0080] Referring now to the drawings, Figure 1The illustration shows a perspective view of one embodiment of a wind turbine 100 according to the present disclosure. The wind turbine 100 may generally include a tower 102 extending from a support surface 104, a nacelle 106 mounted on the tower 102, and a rotor 108 coupled to the nacelle 106. The rotor 108 includes a rotatable hub 110 and at least one rotor blade 112 coupled to and extending outward from the hub 110. For example, in the illustrated embodiment, the rotor 108 includes three rotor blades 112. However, in alternative embodiments, the rotor 108 may include more or fewer than three rotor blades 112. Each rotor blade 112 may be spaced apart around the hub 110 to facilitate rotation of the rotor 108, thereby enabling kinetic energy to be converted from wind energy into usable mechanical energy, and subsequently into electrical energy. For example, the hub 110 may be rotatably coupled to an electrical system 400 located within the nacelle 106. Figure 2 ) generator 118 ( Figure 2 This allows for the generation of electrical energy.

[0081] The wind turbine 100 may also include a controller 200 centralized within the nacelle 106. However, in other embodiments, the controller 200 may be located within any other component of the wind turbine 100 or at a location outside the wind turbine. Furthermore, the controller 200 may be communicatively coupled to any number of components of the wind turbine 100 to control those components. Accordingly, the controller 200 may include a computer or other suitable processing unit. Therefore, in several embodiments, the controller 200 may include suitable computer-readable instructions that, when implemented, configure the controller 200 to perform various functions, such as receiving, transmitting, and / or executing wind turbine control signals.

[0082] Now for reference Figure 2wherein an exemplary power system 400 of the wind turbine 100 is illustrated. As shown, a generator 118 can be coupled to the rotor 108 for generating electrical power from the rotational energy generated by the rotor 108. Accordingly, in embodiments, the power system 400 can include various components for converting the kinetic energy of the rotor 108 into an electrical power output in an acceptable form to a connected power grid 179. For example, in embodiments, the generator 118 can be a DFIG having a generator stator 402 and a generator rotor 404. The generator 118 can be coupled to a stator bus 406 and a power converter 408 via a rotor bus 410. In such a configuration, the stator bus 406 can provide output multiphase power (e.g., three-phase power) from the stator of the generator 118, and the rotor bus 410 can provide output multiphase power (e.g., three-phase power) of the generator rotor 404 of the generator 118. Additionally, the generator 118 can be coupled to a rotor-side converter 412 via the rotor bus 410. The rotor-side converter 412 can be coupled to a line-side converter 414, which in turn can be coupled to a line-side bus 416.

[0083] In embodiments, the rotor-side converter 412 and the line-side converter 414 can be configured for normal operating mode in a three-phase pulse width modulation (PWM) arrangement using insulated gate bipolar transistors (IGBTs) as switching devices 438. Other suitable switching devices can be used, such as insulated gate commutated thyristors, MOSFETs, bipolar transistors, silicon controlled rectifiers, and / or other suitable switching devices. The rotor-side converter 412 and the line-side converter 414 can be coupled across a DC link capacitor 420 via a DC link 418. For example, in embodiments according to the present disclosure, the line-side converter 414 can include three pairs of IGBTs and corresponding three pairs of diodes, which can be used to convert a DC input to an AC output having a desired phase angle.

[0084] In embodiments, the power converter 408 can be coupled to the controller 200, which is configured as a converter controller 202 to control operation of the power converter 408. For example, the converter controller 202 can send control commands to the rotor-side converter 412 and the line-side converter 414 to control the modulation of switching elements used in the power converter 408 to establish a desired generator torque setpoint, active power output, and / or reactive power output.

[0085] As Figure 2Further depicted in the embodiment, the power system 400 can include a transformer 422 that couples the wind turbine 100 to the power grid 179 via a point of interconnection (POI) 436. In embodiments, the transformer 422 can be a 3-winding transformer that includes a high voltage (e.g., greater than 12 KV AC) primary winding 424. The high voltage primary winding 424 can be coupled to the power grid 179. The transformer 422 can also include a medium voltage (e.g., 6 KV AC) secondary winding 426 coupled to the stator bus 406 and a low voltage (e.g., 575 V AC, 690 V AC, etc.) auxiliary winding 428 coupled to the line side bus 416. It should be appreciated that the transformer 422 can be a three-winding transformer as depicted, or alternatively can be a two-winding transformer having only the primary winding 424 and the secondary winding 426; can be a four-winding transformer having the primary winding 424, the secondary winding 426, the auxiliary winding 428, and an additional auxiliary winding; or can have any other suitable number of windings.

[0086] In embodiments, the power system 400 can include various protection features (e.g., circuit breakers, fuses, contactors, and other devices) to control and / or protect various components of the power system 400. For example, in embodiments, the power system 400 can include a grid circuit breaker 430, a stator bus circuit breaker 432, and / or a line side bus circuit breaker 434. The circuit breakers 430, 432, 434 of the power system 400 can connect or disconnect corresponding components of the power system 400 when conditions of the power system 400 approach thresholds (e.g., current thresholds and / or operational thresholds) of the power system 400.

[0087] In embodiments, the line side converter 414 of the power converter 408 can be coupled to the power grid 179 via a converter contactor 440. The converter contactor 440 can have an open operational state / configuration (in which the converter contactor 440 can be non-conductive) and a closed operational state / configuration (in which the converter contactor 440 can be conductive). For example, the converter contactor 440 can include at least one pair of contacts that can be brought into contact with each other to establish the closed operational state and can be separated from each other to establish the open operational state. In embodiments, the converter contactor 440 can include at least one grid side terminal 442. The grid side terminal(s) 442 can be energized by voltage from the power grid 179 in both the open and closed configurations. In embodiments, the converter contactor 440 can also include at least one converter side terminal 444. The converter side terminal(s) 444 can be electrically decoupled from the power grid 179 when the converter contactor 440 is in the open configuration. It should be appreciated that, in embodiments, the converter contactor 440 can be an integral component of the power converter 408.

[0088] In embodiments, the power system 400 can include a filter module 446 disposed between the line side converter 414 and the converter contactor 440. In embodiments, the filter module can be an AC filter configured to limit the harmonic properties of the grid voltage. In embodiments, the filter module 446 can include at least one capacitor 448, at least one resistive element 450, and / or a filter fuse 452. The elements 448, 450, 452 of the filter module 446 can be configured to receive and shape the grid voltage prior to the grid voltage being delivered to the line side converter 414 when the converter contactor 440 is in the closed position.

[0089] In further embodiments, the power system 400 can also include a distortion filter 454 positioned between the converter contactor 444 and the line side converter 414. For example, in embodiments, the distortion filter 454 can be an inductive element positioned in-line between the filter module 446 and the line side converter 414. In such embodiments, the distortion filter 454 can be configured to further shape / condition the grid voltage prior to the grid voltage being delivered to the line side converter 414.

[0090] As Figure 3 depicted in FIG. 1, in embodiments, the wind turbine 100 can include at least one operational sensor 156. The operational sensor(s) 156 can be configured to detect the performance of the wind turbine 100 (e.g., in response to environmental conditions). In embodiments, the operational sensor(s) 156 can be configured to monitor a plurality of power conditions, such as slip, stator voltage and current, rotor voltage and current, line side voltage and current, DC link charge, and / or any other power condition of the wind turbine. Additionally, the operational sensor(s) 156 can be configured to monitor the rotational speed of the rotor 108 and / or the generator rotor 404.

[0091] It should be appreciated that, as used herein, the term "monitor" and variations thereof indicate that the various sensors of the wind turbine 100 can be configured to provide a direct measurement of the parameter being monitored or an indirect measurement of such parameter. Thus, the sensors described herein can be used, for example, to generate signals related to the parameter being monitored, which can then be utilized by the controller 200 to determine a condition or response of the wind turbine 100.

[0092] Referring to Figure 3 and Figure 4 , a plurality of embodiments of a system 300 for controlling a wind turbine 100 according to the present disclosure are presented. As Figure 3As shown in particular, a schematic diagram of one embodiment of suitable components that can be included within the system 300 is illustrated. For example, as shown, the system 300 can include a controller 200 communicatively coupled to the sensor(s) 156. Further, as shown, the controller 200 includes one or more processors 206 and associated memory device(s) 208 that are configured to perform various computer-implemented functions (e.g., perform methods, steps, calculations, etc. as disclosed herein and store relevant data). Additionally, the controller 200 can also include a communication module 210 to facilitate communication between the controller 200 and various components of the wind turbine 100. Moreover, the communication module 210 can include a sensor interface 212 (e.g., one or more analog-to-digital converters) to allow signals transmitted from the sensor(s) 156 to be converted into signals that can be understood and processed by the processor(s) 206. It should be appreciated that the sensor(s) 156 can be communicatively coupled to the communication module 210 using any suitable means. For example, the sensor(s) 156 can be coupled to the sensor interface 212 via a wired connection. However, in other embodiments, the sensor(s) 156 can be coupled to the sensor interface 212 via a wireless connection, such as by using any suitable wireless communication protocol known in the art.

[0093] As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. Additionally, the memory device(s) 208 can generally include memory element(s) including, without limitation, computer readable medium (e.g., random access memory (RAM)), computer readable nonvolatile memory (e.g., flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and / or other suitable memory elements. Such memory device(s) 208 can generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) 206, configure the controller 200 to perform or direct various functions, including, without limitation, generating at least a portion of the required amount of reactive power generation via the generator rotor 404 during speed operation of the generator 118 and delivering the portion to the power grid 179 via the power converter 408 grid-side (S G ) during speed operation of the generator 118 and various other suitable computer-implemented functions as described herein.

[0094] As Figure 4In an embodiment, depicted at 302, the controller 200 of the system 300 can be configured to detect a crossing of the first threshold 304 by an operating parameter 306 of the generator rotor 404. The operating parameter 306 can be indicative of low speed operation of the generator 118. Low speed operation of the generator 118 can include, for example, a generator operating state in which the generator rotor 404 has a rotational speed 308 of less than or equal to 900 RPM when the power grid 179 has an operating frequency of 60 Hz. In further embodiments, low speed operation of the generator 118 can include a generator operating state in which the generator rotor 404 has a rotational speed 308 of less than or equal to 1100 RPM when the power grid 179 has an operating frequency of 50 Hz.

[0095] In an embodiment, the operating parameter 306 can be a generator rotor rotational speed 308 and the first threshold 304 can be a generator rotor rotational speed threshold 310 Figure 5 ). Thus, when the generator rotor rotational speed 308 is at or below the generator rotor rotational speed threshold 310, low speed operation of the generator 118 can be indicated. In such an embodiment, a crossing of the first threshold can occur when the generator rotor rotational speed 308 falls below (e.g., drops below) the generator rotor rotational speed threshold 310. It should be appreciated that the generator rotor rotational speed 308 can be obtained via direct monitoring (e.g., via the sensor(s) 156) and / or can be determined based on another monitored parameter. For example, the generator rotor rotational speed 308 can be derived from a monitored rotational speed of the wind turbine rotor 108 (or other element coupled thereto).

[0096] In a further embodiment, the operating parameter 306 can be a generator rotor voltage magnitude 312 and the first threshold 304 can be a generator rotor voltage threshold magnitude 314 Figure 5 ). Thus, when the generator rotor voltage magnitude 312 is greater than (e.g., exceeds) or equal to the generator rotor voltage threshold magnitude 314, low speed operation of the generator 118 can be indicated. Thus, in an embodiment, detecting a crossing of the first threshold 304 can include receiving, via the controller, data indicative of the generator rotor voltage magnitude 312.

[0097] In an embodiment, receiving data indicative of the generator rotor voltage magnitude 312 can include determining a converter modulation index 316 of a rotor-side converter 412 of the power converter 408. In a further embodiment, the generator rotor voltage magnitude 312 can be determined based on a DC link voltage 318 of a DC link 418 of the power converter 408. It should be appreciated that the generator rotor voltage magnitude 312 can also be obtained via direct monitoring (e.g., via the sensor(s) 156).

[0098] It should be recognized that, as depicted in 320, in an embodiment where operating parameter 306 does not cross the first threshold 304, wind turbine 100 can deliver reactive power to the power grid 179 via bypass 324 of power converter 408. Meeting the reactive power generation requirement 322 via bypass 324 of power converter 408 can be considered the nominal operating state (S) of wind turbine 100. N ()( Figure 5 ).

[0099] In response to operating parameter 306 crossing a first threshold 304, in this embodiment, system 300 may generate at least a portion 326 of the required reactive power generation via generator rotor 404. As depicted in 328, the portion 326 of the required reactive power generation may then be transmitted via the grid side of power converter 408 (S... G ) is transmitted to the power grid 179.

[0100] To generate the required amount of reactive power 326, in an embodiment, the controller 200 may be configured to receive a reactive current setpoint 330 from the generator 118. The reactive current setpoint 330 may correspond to a current setpoint on the generator rotor 404 that facilitates meeting the required amount of reactive power generation via the generator stator 402. In other words, the reactive current setpoint 330 may be set when the wind turbine 100 is in its nominal operating state (S). N The current setpoint of the generator 118 used when operating under the power converter 408 and delivering reactive power to the power grid 179 via the bypass 324 of the power converter 408 to meet the reactive power generation requirement 322 of the power grid 179. The controller 200 can then generate a modified reactive current setpoint 332. The modified reactive current setpoint 332 can be configured to facilitate the generation of the required reactive power generation 322 via the generator rotor 404. As depicted in 334, at least one operating state of the power converter 408 can be changed based on the modified reactive current setpoint 332. For example, in an embodiment, the operating state of at least one of the switching devices 438 can be changed based on the modified reactive current setpoint 332, such that the current of the rotor 404 causes a portion 326 to be transmitted via the power converter 408 (e.g., via the grid side of the power converter 408). G )) Transmitted to the power grid 179.

[0101] In an embodiment, changing the operating state(s) of power converter 408 can facilitate the operation of the power converter 408 via the grid side (S) of the grid. G) to the power grid 179. In such embodiments, all of the reactive power generation demand 322 can be satisfied by the portion 326 of the required reactive power generation delivered to the power grid 179 via the grid side (S G ) of the power converter 408. Thus, the reactive power delivered to the power grid 179 via the grid side (S G ) of the power converter 408 can constitute 100% of the reactive power generation of the wind turbine 100.

[0102] In further embodiments, the portion 326 of the required reactive power generation can be a first reactive power portion 336 of the required reactive power generation. In such embodiments, changing the operating state(s) of the power converter 408 can facilitate satisfying the reactive power generation demand 322 via the reactive power output of the wind turbine 100. The reactive power output of the wind turbine 100 can include the first reactive power portion 336 delivered to the power grid 179 via the grid side (S G ) of the power converter 408 and a second reactive power portion 338 delivered to the power grid 179 via the bypass 324 of the power converter 408. As such, the reactive power generation demand 322 can be satisfied by the combination of the reactive power delivered to the power grid 179 via the grid side (S G ) of the power converter 408 and the reactive power delivered to the power grid 179 via the bypass 324 of the power converter 408. Thus, the portion 326 of the required reactive power generation delivered via the grid side (S G ) of the power converter 408 can be less than 100% of the power generation demand 322.

[0103] In embodiments, delivering the portion 326 of the required reactive power generation to the power grid 179 via the grid side (S G ) of the power converter 408 can facilitate a reduction in the generator rotor voltage magnitude. For example, in the nominal operating state (S N ), reactive power can be delivered to the power grid 179 by the circuit of the generator (e.g., the bypass 324 of the power converter 408). Thus, the reactive current component from the generator rotor 404 can flow through the generator and transformer impedances. As such, when reactive power is delivered to the power grid 179, the rotor voltage magnitude increases, which is exacerbated during low speed operation due to high generator slip. Thus, delivering the portion 326 of the required reactive power generation via the grid side (S G ) of the power converter 408 can reduce the impedance encountered by the portion 326 of the required reactive power generation. This, in turn, can result in a reduction in the generator rotor voltage magnitude.

[0104] It should be appreciated that the reduction in generator rotor voltage magnitude can also help reduce thermal and / or electrical loads across at least one component of the power converter. For example, the reduction in generator rotor voltage magnitude can reduce the required DC link voltage 318. The reduction in required DC voltage 318 can reduce electrical and / or thermal loads on the rotor-side converter 412. This in turn can prevent a reduction in the expected life of the switching devices 438 due to long periods of low speed operation of the wind turbine 100 while meeting the reactive power generation quantity demand 322.

[0105] Still referring to Figure 4 and also referring to Figure 5 where a graphical representation of a relationship 342 of the generator rotor speed 308 and the generator rotor voltage 312 is depicted. As illustrated, when the generator rotor speed 308 is greater than the first threshold 304, the wind turbine 100 can be in a nominal operating state (S N ). As the rotor speed decreases (moving from right to left on the graph), the generator rotor voltage magnitude 312 can increase until the first threshold 304 is crossed and a first voltage magnitude 344 is obtained. Once the first operating parameter 306 crosses the first threshold 304, and the portion of the required reactive power generation 326 is delivered to the power grid 179 via the converter 408, the generator rotor voltage magnitude 312 can decrease, resulting in a second voltage magnitude 346 being obtained. With the portion of the required reactive power generation 326 delivered via the converter 408, the wind turbine 100 can be in a first low speed operating state (S L1 ).

[0106] In embodiments, the wind turbine 100 can continue to operate (e.g., continue to generate active and / or reactive current components) in the first low speed operating state (S L1 ) and the generator rotor speed 308 can continue to decrease. As such, the generator rotor voltage magnitude 312 can increase from the second voltage magnitude 346. Thus, after the portion of the required reactive power generation 326 is delivered to the power grid 179 via the grid-side (S G ) of the power converter 408, the controller 200 can be configured to detect a crossing of a second threshold 350, as depicted at 348. Similar to the first threshold 304, the second threshold 350 can correspond to a generator rotor voltage magnitude and / or a generator rotor rotational speed. Upon reaching the second threshold 350, the rotor voltage magnitude 312 can have a third voltage magnitude 352.

[0107] In response to the crossing of the second threshold 350, the controller 200 can be configured to reduce an active power setpoint 354 and / or a reactive power setpoint 356. By reducing the active power setpoint 354 and / or the reactive power setpoint 356, the wind turbine 100 can be in a second low speed operating state (SL2 ) low speed operation. In the second low speed operation state (S L2 ) the electrical torque of the generator 118 can be significantly reduced (e.g., substantially zero) and a fourth rotor voltage magnitude 358 can be obtained. It should be appreciated that reducing the electrical torque of the generator 118 during the second low speed operation state (S L2 ) can help the wind turbine 100 to remain coupled to the power grid 179, thereby reducing the number of connect / disconnect cycles of the converter contactor 440.

[0108] In embodiments, the second threshold 350 can be based on a predicted reliability of at least one component of the power converter 408. Thus, reducing the active power setpoint 354 and / or the reactive power setpoint 356 can prevent a build-up of wear on components of the power converter 408 during low speed operation of the wind turbine 100.

[0109] In further embodiments, reducing the active power setpoint 354 and / or the reactive power setpoint 356 can help to increase an inertia aspect of the rotor 108 of the wind turbine 100. For example, as the electrical torque aspect decreases in response to the significant reduction in the active power setpoint 354 and / or the reactive power setpoint 356, the amount of power generated, the rotation of the rotor 108 can be nearly frictionless in response to environmental conditions acting on the rotor 108. As such, the rotational speed of the rotor 108 can increase. The resulting increase in the inertia aspect can help to restore active and / or reactive power production.

[0110] Further, those skilled in the art will recognize the interchangeability of various features from different embodiments. Similarly, the various method steps and features described can be mixed and matched by one of ordinary skill in the art to construct additional systems and techniques in accordance with the present disclosure. Of course, it is to be understood that not necessarily all objects or advantages can be achieved in accordance with any particular embodiment described herein. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein can be developed using a variety of alternative technologies and techniques. Furthermore, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, to the extent that the terms "includes," "including," "has," "having" and / or "contains," "containing," or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising."

[0111] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural equivalents to elements of the literal language of the claims, or if they are insubstantial differences from the literal languages of the claims.

[0112] Further aspects of the invention are provided by the subject matter of the following clauses:

[0113] Clause 1. A method for controlling low speed operation of a wind turbine electrically coupled to a power grid, the wind turbine having a generator and a power converter, the generator having a generator rotor and a generator stator, the method comprising: detecting, via a controller, a crossing of a first threshold value by an operating parameter of the generator rotor, the operating parameter indicative of low speed operation of the generator; generating, via the generator rotor, at least a portion of a required reactive power production amount in response to the operating parameter crossing the first threshold value; and delivering, via a grid side of the power converter, the portion of the required reactive power production amount to the power grid.

[0114] Clause 2. The method of clause 1, wherein generating the portion of the required reactive power production amount comprises: receiving, via the controller, a reactive current setpoint for the generator, the reactive current setpoint corresponding to a current of the generator rotor that contributes to meeting the required reactive power production amount via the generator stator; generating, via the controller, a modified reactive current setpoint configured to contribute to generating the portion of the required reactive power production amount via the generator rotor; and changing at least one operating state of the power converter based on the modified reactive current setpoint.

[0115] Clause 3. The method of any preceding clause, wherein the portion of the required reactive power production amount comprises a first reactive power portion of the required reactive power production amount, and wherein changing the at least one operating state of the power converter contributes to meeting the required reactive power production amount via a reactive power output of the wind turbine, the reactive power output comprising the first reactive power portion delivered to the power grid via the grid side of the power converter and a second reactive power portion delivered to the power grid via a bypass of the power converter.

[0116] Clause 4. The method of any preceding clause, wherein changing the at least one operating state of the power converter facilitates satisfying the entirety of the required reactive power production amount by the portion of the required reactive power production amount delivered to the power grid via the grid-side of the power converter.

[0117] Clause 5. The method of any preceding clause, wherein the operating parameter of the generator rotor comprises a generator rotor voltage magnitude, wherein the first threshold comprises a generator rotor voltage threshold magnitude indicative of low speed operation of the generator, and wherein detecting a crossing of the first threshold further comprises receiving, via the controller, data indicative of the generator rotor voltage magnitude.

[0118] Clause 6. The method of any preceding clause, wherein receiving data indicative of the generator rotor voltage magnitude further comprises determining, via the controller, a converter modulation index of a rotor-side converter of the power converter indicative of the generator rotor voltage magnitude.

[0119] Clause 7. The method of any preceding clause, wherein receiving data indicative of the generator rotor voltage magnitude further comprises determining, via the controller, a DC link voltage of a DC link of the power converter indicative of the generator rotor voltage magnitude.

[0120] Clause 8. The method of any preceding clause, wherein the operating parameter of the generator rotor comprises a generator rotor rotational speed, wherein the first threshold comprises a generator rotor rotational speed threshold, and wherein low speed operation of the generator is indicated when the generator rotor rotational speed is at or below the generator rotor rotational speed threshold.

[0121] Clause 9. The method of any preceding clause, wherein delivering the portion of the required reactive power production amount to the power grid via the grid-side of the power converter facilitates a reduction in the generator rotor voltage magnitude.

[0122] Clause 10. The method of any preceding clause, wherein the reduction in the generator rotor voltage magnitude facilitates a reduction in at least one of a thermal load and an electrical load across components of the power converter.

[0123] Clause 11. The method of any preceding clause, further comprising, after the portion of the required reactive power production amount is delivered to the power grid via the grid-side of the power converter, detecting, via the controller, a crossing of a second threshold by the operating parameter of the generator rotor; and in response to the crossing of the second threshold by the operating parameter, reducing, via the controller, at least one of the active power setpoint and the reactive power setpoint of the generator.

[0124] Clause 12. The method of any preceding clause, wherein the second threshold is based on a predicted reliability of at least one component of the power converter.

[0125] Clause 13. The method of any preceding clause, wherein the wind turbine further comprises a rotor rotatably coupled to the generator, the rotor having one or more rotor blades mounted thereto, and wherein reducing at least one of the active power setpoint and the reactive power setpoint of the generator facilitates an increase in an inertia aspect of the rotor of the wind turbine.

[0126] Clause 14. A system for controlling a wind turbine coupled to an electric power grid, the wind turbine having a generator and a power converter, the generator having a generator rotor and a generator stator, the system comprising a controller communicatively coupled to the generator, the controller comprising at least one processor configured to perform a plurality of operations, the plurality of operations comprising: detecting a crossing of a first threshold by an operating parameter of the generator rotor, the operating parameter indicative of a low speed operation of the generator; generating, via the generator rotor, at least a portion of a required reactive power production in response to the operating parameter crossing the first threshold; and delivering, via a grid side of the power converter, the portion of the required reactive power production to the electric power grid.

[0127] Clause 15. The system of any preceding clause, wherein generating the portion of the required reactive power production comprises: receiving a reactive current setpoint for the generator, the reactive current setpoint corresponding to a current of the generator rotor that facilitates meeting the required reactive power production via the generator stator; generating a modified reactive current setpoint configured to facilitate generating the portion of the required reactive power production via the generator rotor; and changing at least one operating state of the power converter based on the modified reactive current setpoint.

[0128] Clause 16. The system of any preceding clause, wherein the portion of the required reactive power production comprises a first reactive power portion of the required reactive power production, and wherein changing the at least one operating state of the power converter facilitates meeting the required reactive power production via a reactive power output of the wind turbine, the reactive power output comprising the first reactive power portion delivered to the electric power grid via the grid side of the power converter and a second reactive power portion delivered to the electric power grid via a bypass of the power converter.

[0129] Clause 17. The system of any preceding clause, wherein the operating parameter of the generator rotor comprises a generator rotor voltage magnitude, wherein the first threshold comprises a generator rotor voltage threshold magnitude indicative of low speed operation of the generator, and wherein detecting a crossing of the first threshold further comprises receiving data indicative of the generator rotor voltage magnitude.

[0130] Clause 18. The system of any preceding clause, wherein the operating parameter of the generator rotor comprises a generator rotor rotational speed, wherein the first threshold comprises a generator rotor rotational speed threshold, and wherein low speed operation of the generator is indicated when the generator rotor rotational speed is at or below the generator rotor rotational speed threshold.

[0131] Clause 19. The system of any preceding clause, wherein delivering the portion of the required reactive power generation amount to the power grid via the grid side of the power converter facilitates reducing a generator rotor voltage magnitude, wherein a reduction in the generator rotor voltage magnitude facilitates reducing at least one of a thermal load and an electrical load across components of the power converter.

[0132] Clause 20. The system of any preceding clause, wherein the plurality of operations further comprise: after the portion of the required reactive power generation amount is delivered to the power grid via the grid side of the power converter, detecting a crossing of a second threshold by the operating parameter of the generator rotor; and in response to the operating parameter approaching the second threshold, reducing at least one of an active power setpoint and a reactive power setpoint of the generator.

Claims

1. A method for controlling low speed operation of a wind turbine electrically coupled to a power grid, the wind turbine having a generator and a power converter, the generator having a generator rotor and a generator stator, the method comprising: detecting, via a controller, a crossing of a first threshold value by an operating parameter of the generator rotor, the operating parameter indicative of low speed operation of the generator; in response to the operating parameter crossing the first threshold value, generating, via the generator rotor, at least a portion of a required reactive power generation amount, wherein generating the portion of the required reactive power generation amount comprises: receiving, via the controller, a reactive current setpoint for the generator, the reactive current setpoint corresponding to a current of the generator rotor that contributes to meeting the required reactive power generation amount via the generator stator; generating, via the controller, a modified reactive current setpoint configured to contribute to generating the portion of the required reactive power generation amount via the generator rotor, wherein the portion of the required reactive power generation amount comprises a first reactive power portion of the required reactive power generation amount; and changing, based on the modified reactive current setpoint, at least one operating state of the power converter to contribute to meeting the required reactive power generation amount via a reactive power output of the wind turbine, the reactive power output comprising the first reactive power portion delivered to the power grid via a grid side of the power converter and a second reactive power portion delivered to the power grid via a bypass of the power converter; and delivering, via the grid side of the power converter, the portion of the required reactive power generation amount to the power grid.

2. The method of claim 1, wherein, Changing the at least one operating state of the power converter contributes to meeting the entirety of the required reactive power generation amount by the portion of the required reactive power generation amount delivered to the power grid via the grid side of the power converter.

3. The method of claim 1, wherein, The operating parameter of the generator rotor comprises a generator rotor voltage magnitude, wherein the first threshold value comprises a generator rotor voltage threshold magnitude indicative of the low speed operation of the generator, and wherein detecting the crossing of the first threshold value further comprises: receiving, via the controller, data indicative of the generator rotor voltage magnitude.

4. The method of claim 3, wherein, Receiving data indicative of the generator rotor voltage magnitude further comprises: determining, via the controller, a converter modulation index of a rotor side converter of the power converter indicative of the generator rotor voltage magnitude.

5. The method of claim 3, wherein, Receiving data indicative of the generator rotor voltage magnitude further comprises: determining, via the controller, a DC link voltage of a DC link of the power converter indicative of the generator rotor voltage magnitude.

6. The method of claim 1, wherein, The operating parameter of the generator rotor comprises a generator rotor rotational speed, wherein the first threshold value comprises a generator rotor rotational speed threshold, and wherein the low speed operation of the generator is indicated when the generator rotor rotational speed is at or below the generator rotor rotational speed threshold.

7. The method of claim 1, wherein, Delivering the portion of the required reactive power production to the power grid via the grid side of the power converter facilitates a reduction in a generator rotor voltage magnitude.

8. The method of claim 7, wherein, The reduction in the generator rotor voltage magnitude facilitates a reduction in at least one of a thermal load and an electrical load across components of the power converter.

9. The method of claim 1, further comprising: detecting, via the controller, a crossing of a second threshold by the operating parameter of the generator rotor after the portion of the required reactive power production is delivered to the power grid via the grid side of the power converter; and in response to the crossing of the second threshold by the operating parameter, reducing, via the controller, at least one of an active power setpoint and a reactive power setpoint of the generator.

10. The method of claim 9, wherein, The second threshold is based on a predicted reliability of at least one component of the power converter.

11. The method of claim 9, wherein, The wind turbine further includes a rotor rotatably coupled to the generator, the rotor having one or more rotor blades mounted to the rotor, and wherein reducing at least one of the active power setpoint and the reactive power setpoint of the generator facilitates an increase in an inertia aspect of the rotor of the wind turbine.

12. A system for controlling a wind turbine coupled to a power grid, the wind turbine having a generator and a power converter, the generator having a generator rotor and a generator stator, the system comprising a controller communicatively coupled to the generator, the controller comprising at least one processor configured to perform a plurality of operations, the plurality of operations comprising: detecting a crossing of a first threshold by an operating parameter of the generator rotor, the operating parameter indicative of a low speed operation of the generator; in response to the operating parameter crossing the first threshold, generating at least a portion of a required reactive power production via the generator rotor, wherein generating the portion of the required reactive power production comprises: receiving a reactive current setpoint of the generator, the reactive current setpoint corresponding to a current of the generator rotor, the current facilitating satisfaction of the required reactive power production via the generator stator; generating a modified reactive current setpoint, the modified reactive current setpoint configured to facilitate generation of the portion of the required reactive power production via the generator rotor, wherein the portion of the required reactive power production comprises a first reactive power portion of the required reactive power production; and based on the modified reactive current setpoint, changing at least one operating state of the power converter to facilitate satisfaction of the required reactive power production via a reactive power output of the wind turbine, the reactive power output comprising the first reactive power portion delivered to the power grid via a grid side of the power converter and a second reactive power portion delivered to the power grid via a bypass of the power converter; and delivering the portion of the required reactive power production to the power grid via the grid side of the power converter.

13. The system of claim 12, wherein, The operating parameter of the generator rotor includes a generator rotor voltage magnitude, wherein the first threshold includes a generator rotor voltage threshold magnitude indicative of the low speed operation of the generator, and wherein detecting the crossing of the first threshold further includes: receiving data indicative of the generator rotor voltage magnitude.

14. The system of claim 12, wherein, The operating parameter of the generator rotor includes a generator rotor rotational speed, wherein the first threshold includes a generator rotor rotational speed threshold, and wherein the low speed operation of the generator is indicated when the generator rotor rotational speed is at or below the generator rotor rotational speed threshold.

15. The system of claim 12, wherein, The delivery of the portion of the required reactive power generation to the power grid via the grid side of the power converter facilitates a reduction in a generator rotor voltage magnitude, wherein the reduction in the generator rotor voltage magnitude facilitates a reduction in at least one of a thermal load and an electrical load across components of the power converter.

16. The system of claim 12, wherein, The plurality of operations further include: detecting, after the portion of the required reactive power generation is delivered to the power grid via the grid side of the power converter, a crossing of a second threshold by the operating parameter of the generator rotor; and in response to the operating parameter approaching the second threshold, reducing at least one of an active power setpoint and a reactive power setpoint of the generator.

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