WIND POWER PLANT WITH POWER CONVERSION SYSTEM

Abstract

A wind power plant for providing electrical power to a utility grid is provided, the wind power plant including: at least one wind turbine having a wind turbine generator coupled to a wind turbine rotation shaft to which plural rotor blades are mounted, the wind turbine providing electric power at an output terminal; at least one power conversion system, each including: a plant motor electrically coupled and configured to receive the electric power from the output terminal of the at least one wind turbine and convert it into rotational power of a plant motor shaft; a plant generator mechanically coupled to the plant motor shaft and electrically coupleable to the electric utility grid.

Claims

1. A wind power plant for providing electrical power to a utility grid, the wind power plant comprising: at least one wind turbine having a wind turbine generator coupled to a wind turbine rotation shaft to which plural rotor blades are mounted, the wind turbine providing electric power at an output terminal; at least one power conversion system, each comprising: a plant motor electrically coupled and configured to receive the electric power from the output terminal of the at least one wind turbine and convert it into rotational power of a plant motor shaft; a plant generator mechanically coupled to the plant motor shaft and electrically coupleable to the electric utility grid; wherein at least one of power conversion systems further comprising: a power conversion system controller being configured to control active power at a power conversion system output terminal based on at least one reference value related to the utility grid; wherein the power conversion system controller comprises a plant motor controller communicatively coupled to the plant motor and a plant generator controller communicatively coupled the plant generator; and wherein the plant motor controller is configured to receive a plant active power reference signal, to determine individual active power reference signals for the at least one wind turbine and/or the at least one of power generating component based on the plant active power reference signal and supply the individual active power reference signals to the at least one wind turbine and/or the power generating component.

2. The wind power plant according to claim 1, wherein the plant generator and/or the plant motor of at least one of the at least one power conversion system comprises a synchronous machine.

3. The wind power plant according to claim 1, wherein at least one of power conversion systems further comprising: a mechanical inertial mass, coupled or couplable to the respective plant motor shaft.

4. The wind power plant according to claim 1, wherein a value of inertia of the wind power plant amounts to between 2 sec and 5 sec.

5. The wind power plant according to claim 1, wherein the power conversion system controller is further configured to control the active power at a power conversion system output terminal and/or at the utility grid and/or at a power conversion system input terminal based on at least one reference value and/or measurement values related to the utility grid and/or related to a plant grid.

6. The wind power plant according to claim 1, wherein the power conversion system controller is further configured to control reactive power and/or voltage at a power conversion system output terminal and/or at the utility grid and/or at a power conversion system input terminal based on at least one reference value and/or measurement values related to the utility grid and/or related to a plant grid.

7. The wind power plant according to claim 1, further comprising at least one power generating component being different from a wind turbine and being connected such as to supply electrical power and/or mechanical power to the plant motor, the power generating component comprising at least one of: at least one photovoltaic cell; at least one thermal energy storage; at least one electric energy storage; at least one steam turbine; at least one gas turbine; and wherein at least one power generating component enables black start of the wind power plant in case of insufficient wind.

8. The wind power plant according to claim 1, wherein the plant motor controller is configured to control the plant grid voltage by controlling the plant motor to output a reference plant grid reactive power to the plant grid,

9. The wind power plant according to claim 8, wherein to control the plant grid voltage the plant motor controller utilizes an automatic voltage regulator that receives measurement values regarding plant grid voltage.

10. The wind power plant according to claim 1, wherein the plant generator controller is configured to control the plant generator to output a reference utility grid reactive power to the utility grid; the plant generator controller utilizing an automatic voltage regulator that receives measurement values regarding utility grid voltage.

11. The wind power plant according to claim 1, further comprising a load frequency controller configured: to receive measurement values of a utility grid frequency; to determine a plant active power reference signal based on the utility grid frequency; and to supply the plant active power reference signal to the plant motor controller.

12. The wind power plant according to claim 1, at least one wind turbine further comprising: a wind turbine converter connected to the wind turbine generator for converting the generator power to a substantially fixed frequency power supplied to the wind turbine output terminal; and/or the plant further comprising: a plant transformer coupled to the output terminal of all of the at least one power conversion system, in order to transform a voltage provided to the electrical utility grid to a higher value.

13. The wind power plant according to claim 1, wherein the plant comprises exactly one power conversion system to which all wind turbines supply their output power.

14. The wind power plant according to claim 1, wherein the plant comprises at least two power conversion systems whose output terminals are electrically connected to a bus bar which is electrically connected to the utility grid, via a plant transformer.

15. The wind power plant according to claim 1, further comprising a hydrogen plant.

Description

BRIEF DESCRIPTION

[0057] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0058] FIG. 1 schematically illustrates a wind power plant according to an embodiment of the present invention;

[0059] FIG. 2 schematically illustrates a wind power plant according to another embodiment of the present invention;

[0060] FIG. 3 schematically illustrates a wind power plant according to still another embodiment of the present invention; and

[0061] FIG. 4 schematically illustrates a wind power plant according to an embodiment of the present invention with emphasis of control features.

DETAILED DESCRIPTION

[0062] The illustration in the drawings is in schematic form. It is noted that in different figures, elements similar or identical in structure and/or function are provided with the same reference signs or with reference signs, which differ only within the first digit. A description of an element not described in one embodiment may be taken from a description of this element with respect to another embodiment.

[0063] The wind power plant 100 schematically illustrated in FIG. 1 is for providing electrical power to a utility grid 101. The wind power plant 100 thereby comprises at least one wind turbine 103 having a (not illustrated) wind turbine generator coupled to a wind turbine rotation shaft 105 at which plural rotor blades 107 are mounted. The wind turbine provides electrical power at an output terminal 109.

[0064] The wind power plant 100 further comprises at least one power conversion system 110 which comprises a plant motor 111 which is electrically coupled and configured to receive the electric power from the output terminal 109 of the at least one wind turbine 103. The plant motor 111 is further configured to convert the received electrical power into rotational power of a plant motor shaft 113. The power conversion system 110 further comprises a plant generator 115 which is mechanically coupled to the plant motor shaft 113 and which is electrically coupled or couplable to the utility grid 101. In the embodiment 100 of the wind power plant illustrated in FIG. 1, the plant generator 115 as well as the plant motor 111 are configured as synchronous machines.

[0065] Furthermore, in the embodiment 100 of the wind power plant illustrated in FIG. 1, the power conversion system comprises a mechanical inertial mass 117 which may for example be configured as a flywheel. The mechanical inertial mass 117 is coupled to the plant motor shaft 113. In particular, the plant motor shaft 113 and another shaft or a continuation of the plant motor shaft 119 are rotatably supported by respective bearings 121.

[0066] In the embodiment 100 illustrated in FIG. 1, plural other wind turbines 103 are, together with the at least one wind turbine 103, connected with their corresponding output terminals 109 to a common busbar 123 which is electrically connected at an input terminal 125 (e.g., representing an input terminal of power conversion system 110) of the plant motor. Thus, the accumulated electrical power 127 generated by the plural wind turbines 103 is supplied as a driving power to the plant motor 111.

[0067] The wind power plant 100 and in particular the power conversion system 110 further comprises a power conversion system controller 129 which is configured to control active power and/or reactive power and/or voltage at a power conversion system output terminal 131 and/or at a power conversion system input terminal which is in the illustrated embodiment established by the terminal 125 of the plant motor 111. For the control, the power conversion system controller 129 may receive measurement values related to the utility grid 101 or related to a plant grid constituted by power cables 133 including the busbar 123 and further not illustrated power cables. The power conversion system controller 129 is communicatively connected to the plant generator 115 as well as to the plant motor 111 and will be described in more detail with reference to FIG. 4 below.

[0068] FIG. 1 illustrates an embodiment 100 of a wind power plant which is configured as a centralized variant, wherein this wind power plant comprises exactly one power conversion system 110 to which the accumulated power 127 of all wind turbines 103 is supplied.

[0069] At least one wind turbine 103 of the wind power plant 100 may comprise a wind turbine converter (not illustrated) connected to the wind turbine generator for converting the generator power to a substantially fixed frequency power supplied to the wind turbine output terminal 109.

[0070] The embodiment 100 of the power plant further comprises a plant transformer 135 which is coupled to the output terminal 131 of all of the at least one power conversion system 110, in order to transform a voltage provided to the electrical utility grid 101 to a higher value. Thereby, the plant transformer comprises a low voltage side 136 and a high voltage side 138. As is illustrated with three power lines 139a, 139b, 139c, the AC power 141 output by the power conversion system 110 is a three-phase AC power. The AC power 141 may be transmitted via a transmission line to plural consumers.

[0071] FIG. 2 schematically illustrates a wind power plant 200 according to another embodiment of the present invention. The wind power plant 200 has similarities with the wind power plant 100 illustrated in FIG. 1, but is here configured as a decentralized version. Therein, the wind power plant comprises plural power conversion systems 210a, 210b, 210c. Each one of the plural power conversion systems is electrically coupled to at least one wind turbine, i.e., at least one wind turbine 203a or at least one wind turbine 203b or at least one wind turbine 203c, respectively. The respective output terminals 231a, 231b, 231c of the respective power conversion systems 210a, 210b, 210c are electrically connected to a busbar 234 which is connected to the plant transformer 235.

[0072] FIG. 3 schematically illustrates a wind power plant 300 according to an embodiment of the present invention, wherein the wind power plant further, different from the wind power plants 100 and 200 illustrated in FIGS. 1 and 2, comprises at least one power generating component 341a, 341b which is different from a wind turbine, and which is connected such as to supply the electrical power and/or the mechanical power to the plant motor 311. The at least one power generating component may be at least one of: at least one photovoltaic cell; at least one thermal energy storage; at least one steam turbine; at least one gas turbine, and/or at least an Electric Power Storage system, e.g., Li-ion batteries.

[0073] In the illustrated embodiment, the power generating component 341a is configured as or comprises a plurality of photovoltaic cells 343. Furthermore, the power generating component 341b is configured as a steam turbine system which comprises thermal storage plant 345 and a steam turbine 347 comprising tubing or piping 349 which conduct hot steam which has been heated up in a heat exchanger 351 comprised within the thermal storage plant 345. Herein, the thermal storage plant comprises an electrical heater 353 which may be operated by using AC power via electrical cables 355 from the at least one wind turbine 303. The turbine system 341b further comprises a pump 357 as well as a valve 359, in order to circulate the steam within the tubing 349 and lead it via the heat exchanger 351 to the steam turbine 347. The steam turbine 347 comprises a steam turbine shaft 361 which is mechanically coupled to the motor shaft 313 of the plant motor 317. Thus, upon rotation of the steam turbine shaft 361, the motor 317 is mechanically driven additionally to the driving of the motor by the electric energy or electric power 327 received from the wind turbines 303 as well as from the photovoltaic plant 341a. Since the photovoltaic cells 343 generate DC power, a DC-AC converter 363 is connected to the output terminal of the photovoltaic cells 343 to convert the DC power into AC power having the same frequency (for example 50 Hz or 60 Hz) as the AC power as generated by the wind turbines 303.

[0074] During certain conditions, e.g., highly favourable weather conditions, the wind power plant according to any of the examples disclosed, may generate more power than it can inject to grid and/or store, therefore leading to a surplus of energy. In such cases, the wind power plant may usually avoid generating more power than it can inject and/or store.

[0075] In order to avoid not generating such extra energy, in some examples (not shown), the wind power plant may further comprise a Hydrogen plant. Therefore, in the event a surplus of energy is generated, the Hydrogen plant may receive such generated extra energy to produce green Hydrogen (H2).

[0076] The hydrogen power plant may be connected to the output of the at least one wind turbine and/or to at least one power generating component e.g., one thermal energy storage or an Electric Power Storage system, in order to obtain power for operating i.e., to generate hydrogen when a surplus of energy is generated.

[0077] Thus, the wind power plant may be more efficient as any surplus energy may be employed on Hydrogen generation rather losing or not generating it. Additionally, the maximum energy generating capacity of the wind power plant may be ensured thereby further improving the efficiency of the wind power plant.

[0078] In examples wherein the wind power plant comprises a Hydrogen plant, the power conversion system controller may determine the amount or percentage of generated power to be injected to grid, stored and/or provided to the Hydrogen plant. In an example, about 40-60% of the generated power may be injected to the grid, about 20-40% of the generated power may be stored and about 10-20% of the generated power may be provided to the Hydrogen plant.

[0079] Embodiments of the present invention provide a wind power plant as a “real grid forming synchronous renewable plant (RGFSRP)” wherein two synchronous machines are used and coupled on a mechanical shaft. One of these machines, i.e., the plant generator 115, is coupled to the plant motor 111, such that the plant motor drives the plant generator 115. A mechanical inertia (such as flywheel 117) can optionally be included to provide the inertia that could be required by the utility grid 101. Thereby, in particular, frequency support of the utility grid can be provided. Also, a steam turbine, for example steam turbine 347 illustrated in FIG. 3, may optionally be included to provide thermal energy storage to assure energy during no renewable energy time/days, i.e., when no wind or no sufficient sun irradiation is present.

[0080] Synchronous machines may be commonly used in conventional power plants. Furthermore, it is proposed to use a similar or same control as in a conventional power plant for controlling the synchronous machines. FIG. 4 schematically illustrates a wind power plant 400 according to still another embodiment of the present invention, wherein emphasis is put on control issues. The power generating equipment 441a, 441b are similar to the power generating equipment 341a, 341b illustrated in FIG. 3 and they are also similarly connected to the respective power output terminals of the at least one wind turbine 403.

[0081] The power conversion system controller 429 of the embodiment 400 of the power plant illustrated in FIG. 4 comprises a plant motor controller 463 and a plant generator controller 465. The plant motor controller 463 is configured to receive a plant active power reference signal 467 and is configured to determine individual active power reference signals 469 for the at least one wind turbine 403 and/or the at least one power generating component 441a, 441b and supply the individual active power reference signals 469 to the at least one wind turbine 403 and/or the power generating component 441a, 441b. The plant motor controller 463 is further configured to control the plant grid voltage by controlling the plant motor 411 to output a reference plant grid reactive power to the plant grid 423, 433. Thereby, the plant motor controller 463 utilizes an automatic voltage regulator 471 which receives measurement values 473 regarding plant grid voltage from a voltage sensor 475. The automatic voltage regulator 471 outputs control signals to excitation system 472 that controls motor stator windings 474.

[0082] The plant generator controller 465 is configured to control the plant generator 415 to output a reference utility grid reactive power to the utility grid 401. Thereby, the plant generator controller utilizes an automatic voltage regulator 477 which receives measurement values 479 from a grid sensor 481 which measures electrical properties, such as voltage of the utility grid 401. The automatic voltage regulator 477 outputs control signals to excitation system 470 that controls generator stator windings 476.

[0083] Furthermore, the wind power plant 400 comprises a load frequency controller 483 which is configured to receive measurement values of the utility grid frequency from the sensors 481 and to determine a plant active power reference signal 485 based on the utility grid frequency. Furthermore, the load frequency controller 483 is configured to supply the plant active power reference signal 485 to the plant motor controller 463, in particular via the signal 467.

[0084] Furthermore, the plant active power reference signal 485 is also supplied to the photovoltaic plant 441a, in particular to a photovoltaic plant controller 487. Furthermore, the plant active power reference signal is supplied to the wind turbine 403, in particular via a wind turbine controller 489. In particular, a module 488 calculates an individual wind power reference for the wind turbine and a module 486 calculates an individual photovoltaic cell reference for the photovoltaic plant 441a.

[0085] The plant active power reference signal 485 is also supplied to the steam turbine system 441b, via a module 491 which calculates therefrom an individual turbine power reference, and which is supplied to a thermal storage controller 493 which controls the thermal storage as well as the steam turbine.

[0086] According to an embodiment, the real grid forming synchronous renewable plant for example illustrated in FIGS. 1, 2, 3, 4, provides a shaft torque to the plant generator by the renewable plant motor and/or the energy storage turbine. Therefore, the load frequency controller 483 sends the torque reference to the renewable plant motor and turbine controls. The renewable plant motor control sends the power references to the renewable devices or could be configured in maximum power point tracker (MPPT).

[0087] In an embodiment of the real grid forming synchronous renewable plant, the voltage and the reactive power delivery to the grid may be controlled by the plant generator automatic voltage regulator. In an embodiment, the voltage and the reactive power delivery to the renewable plant devices are controlled by the plant motor automatic voltage regulator. The plant motor automatic voltage regulator can be configured to operate the renewable plant devices at their maximum efficiency point.

[0088] The renewable plant devices can be designed independently to the country-specific grid code requirements using the same standardized hardware and software all over the world. The renewable plant generator, the plant motor and their controls may be designed to comply with the grid code requirements of the particular countries or areas.

[0089] In an embodiment of the real grid forming synchronous renewable plant, with energy storage capability, the plant generator may assure the same power quality and availability as a conventional power plant.

[0090] The plant generator, for example plant generator 115, 215, 315, 415 illustrated in FIGS. 1 to 4, may be a synchronous machine to simplify the system. It needs to be a wound machine (not PMS) to be able to control the flux (of the stator or the permanent magnets).

[0091] Embodiments of the present invention may provide the following advantages:

[0092] The grid power quality may be improved in particular to the same level as a conventional power plant, for example a fossil fuel-based power plant. Cost reduction and standardization of electrical components may be achieved, and the design may be optimized from electrical side assessment point of view.

[0093] The cost of the wind turbines may be reduced, in particular regarding the mechanical parts. The equipment may be optimized in efficiency and optimized in mechanical load resistance due to more time to respond to electrical grid events (i.e., lower pitch speed requirements).

[0094] Embodiments of the present invention may enable easier and cheaper integration of wind energy with energy storage plants that need grid synchronous generators.

[0095] Furthermore, higher availability and reduced downtime can be achieved with the introduction of redundant synchronous generators in the same drive.

[0096] The power conversion system may further provide compliance with future grid code requirements while the wind turbines itself may not be needed to be replaced or changed. Furthermore, the electrical studies necessary to integrate new wind power plants into the electrical grid may be simplified.

[0097] Systems in simplicity may translate also into higher reliability and lower maintenance of the wind power plant.

[0098] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0099] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.