CN216872860U

CN216872860U - Double-fed asynchronous wind generating set and power transmission system of wind generating set

Info

Publication number: CN216872860U
Application number: CN202123443099.7U
Authority: CN
Inventors: 李岩; 艾斯卡尔
Original assignee: Xinjiang Goldwind Science and Technology Co Ltd
Current assignee: Jinfeng Technology Co ltd
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2022-07-01
Anticipated expiration: 2031-12-30

Abstract

The embodiment of the application provides double-fed asynchronous wind generating set and wind generating set's transmission of electricity system, and double-fed asynchronous wind generating set includes: a generator; the rotor-side converter is electrically connected with a rotor of the generator and used for adjusting the frequency of the alternating current output by the rotor to a target frequency, and the target frequency is less than 50 Hz; and the stator side converter is electrically connected with the stator of the generator and is used for adjusting the frequency of the alternating current output by the stator to a target frequency. The embodiment of the application can reduce the refitting cost or the design cost of the double-fed asynchronous wind generating set.

Description

Double-fed asynchronous wind generating set and power transmission system of wind generating set

Technical Field

The application belongs to the technical field of wind power generation, and particularly relates to a double-fed asynchronous wind generating set and a power transmission system of the wind generating set.

Background

With the rapid development of new energy technology, the application range of new energy is wider and wider. Among them, the wind power generation technology is one of the technologies focused on.

In the process of wind power generation, a wind generating set converts wind energy into electric energy, and then the electric energy is merged into a power grid through a power transmission line. However, the inventor of the present application has found that the cost of power transmission and the cost of retrofitting of the current wind turbine generator system are high.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a double-fed asynchronous wind generating set and a power transmission system of the wind generating set, and the technical problem that the modification cost of the wind generating set is high can be at least solved.

In a first aspect, an embodiment of the present application provides a doubly-fed asynchronous wind turbine generator system, which includes: a generator; the rotor-side converter is electrically connected with a rotor of the generator and used for adjusting the frequency of the alternating current output by the rotor to a target frequency, and the target frequency is less than 50 Hz; and the stator side converter is electrically connected with the stator of the generator and is used for adjusting the frequency of the alternating current output by the stator to a target frequency.

In a second aspect, an embodiment of the present application provides a power transmission system of a wind turbine generator system, where the power transmission system of the wind turbine generator system includes: the double-fed asynchronous wind generating set comprises a generator and a rotor-side converter, wherein the rotor-side converter is electrically connected with a rotor of the generator and is used for adjusting the frequency of alternating current output by the rotor to a target frequency, and the target frequency is less than 50 Hz; the low-voltage side of the first boosting transformer is electrically connected with a stator-side converter and a rotor-side converter of the generator respectively, and the high-voltage side of the first boosting transformer is electrically connected with a power grid; and the first converter is electrically connected between the stator and the power grid and is used for adjusting the frequency of the alternating current output by the stator to a target frequency.

Therefore, in the embodiment of the application, the frequency of the alternating current output by the generator is adjusted to be less than 50Hz through the rotor-side converter and the first converter, so that on one hand, the maximum power which can be transmitted by a power transmission system of the wind generating set can be improved, namely, the power transmission capacity of the power transmission system of the wind generating set is improved; on the other hand, the voltage drop of a power transmission line in a power transmission system of the wind generating set can be reduced, and the voltage stability of the power transmission system is maintained; in another aspect, the loss of the power transmission cable can be reduced, and the service life of the power transmission cable can be prolonged.

According to an embodiment of the second aspect of the present application, the first converter is electrically connected between the stator and the low voltage side of the first step-up transformer.

Therefore, the frequency of the alternating current output by the stator can be adjusted to the target frequency smaller than 50Hz through the first converter between the stator of the generator and the low-voltage side of the first booster transformer, and the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency smaller than 50Hz under the condition that the generator in the double-fed asynchronous wind generating set is not required to be redesigned, so that the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

According to any of the embodiments of the second aspect of the present application, the input terminal of the rotor-side converter is electrically connected to the rotor, the input terminal of the first converter is electrically connected to the stator, and the output terminal of the rotor-side converter and the output terminal of the first converter are electrically connected to the low voltage side of the first step-up transformer.

Therefore, the frequency of the alternating current output by the stator can be adjusted to the target frequency smaller than 50Hz by the first converter arranged on the stator side, and the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency smaller than 50Hz under the condition that the generator in the double-fed asynchronous wind generating set is not required to be redesigned, so that the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

According to any one of the embodiments of the second aspect of the present application, the input terminal of the rotor-side converter is electrically connected to the rotor, the input terminal of the first converter is electrically connected to the output terminals of the stator-side converter and the rotor-side converter, respectively, and the output terminal of the first converter is electrically connected to the low-voltage side of the first step-up transformer.

Therefore, the frequency of the alternating current output by the stator can be adjusted to the target frequency smaller than 50Hz by the first converter arranged on the low-voltage side of the first booster transformer, and the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency smaller than 50Hz under the condition that a generator in the double-fed asynchronous wind generating set is not required to be redesigned, so that the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

According to any one of the preceding embodiments of the second aspect of the present application, the first converter is electrically connected between the high voltage side of the first step-up transformer and the grid.

Therefore, the frequency of the alternating current output by the stator can be adjusted to the target frequency smaller than 50Hz by the first converter arranged on the high-voltage side of the first booster transformer, and the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency smaller than 50Hz under the condition that a generator in the double-fed asynchronous wind generating set is not required to be redesigned, so that the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

According to any one of the previous embodiments of the second aspect of the present application, the target frequency is any one of a first frequency range, the first frequency range comprising 8Hz to 21 Hz.

Therefore, the frequency of the alternating current output by the generator is adjusted to 8Hz to 21Hz through the rotor side converter and the first converter, so that the wind power generator set outputs the low-frequency alternating current of 8Hz to 21Hz, and on one hand, the maximum power which can be transmitted by a power transmission system of the wind power generator set can be improved, namely, the power transmission capacity of the power transmission system of the wind power generator set is improved; on the other hand, the voltage drop of a power transmission line in a power transmission system of the wind generating set can be reduced, and the voltage stability of the power transmission system is maintained; in another aspect, the loss of the power transmission cable can be reduced, and the service life of the power transmission cable can be prolonged.

According to any one of the preceding embodiments of the second aspect of the present application, the target frequency comprises 50/3 Hz.

Therefore, according to the embodiment of the application, the frequency of the alternating current output by the generator is adjusted to 50/3Hz through the rotor-side converter and the first converter, so that the wind generating set outputs 50/3Hz low-frequency alternating current, and on one hand, the maximum power which can be transmitted by a power transmission system of the wind generating set can be improved, namely, the power transmission capacity of the power transmission system of the wind generating set is improved; on the other hand, the voltage drop of a power transmission line in a power transmission system of the wind generating set can be reduced, and the voltage stability of the power transmission system is maintained; in another aspect, the loss of the power transmission cable can be reduced, and the service life of the power transmission cable can be prolonged.

According to any of the preceding embodiments of the second aspect of the present application, the power transmission system further comprises a second step-up transformer, the low-voltage side of which is electrically connected to the high-voltage side of the at least one first step-up transformer, and the high-voltage side of which is electrically connected to the grid via a power transmission cable.

Therefore, before the alternating current output by the wind generating set is transmitted remotely through the power transmission cable, the voltage value of the alternating current output by the high-voltage side of the first step-up transformer is further increased to a higher voltage value by additionally arranging the second step-up transformer, so that the loss of electric energy in the remote transmission process is reduced, and the energy utilization rate is improved.

According to any of the preceding embodiments of the second aspect of the present application, the power transmission system further comprises a second converter, an input end of the second converter is electrically connected with the high voltage side of the second step-up transformer through a power transmission cable, an output end of the second converter is electrically connected with the power grid, and the second converter is configured to adjust the frequency of the alternating current output by the second step-up transformer from the target frequency to 50 Hz.

Therefore, according to the embodiment of the application, the frequency of the alternating current output by the generator is adjusted to the low frequency smaller than 50Hz through the rotor side converter and the first converter, so that the wind generating set outputs the low-frequency alternating current, the power transmission capacity of a power transmission system of the wind generating set is improved, the voltage stability of the power transmission system of the wind generating set is kept, the service life of a power transmission line in the power transmission system of the wind generating set is prolonged, and the power transmission cost is reduced. Then, the frequency of the alternating current is adjusted to 50Hz from the low frequency less than 50Hz by the second converter, so that the frequency requirement of the alternating current for daily household is met.

According to an embodiment of the second aspect of the present application, the power transmission system further comprises a first step-down transformer or a third step-up transformer, wherein: the high-voltage side of the first step-down transformer is electrically connected with the high-voltage side of the second step-up transformer through a power transmission cable, and the low-voltage side of the first step-down transformer is electrically connected with a power grid; the low-voltage side of the third step-up transformer is electrically connected with the high-voltage side of the second step-up transformer through a power transmission cable, and the high-voltage side of the third step-up transformer is electrically connected with a power grid.

Therefore, the first step-down transformer or the third step-up transformer is additionally arranged, so that the alternating current output by the power transmission system of the wind generating set can be converted into the alternating current with the expected target voltage value, and different power utilization requirements of people in production or life are met.

The asynchronous wind generating set of double-fed and wind generating set's of this application embodiment transmission of electricity system, the asynchronous wind generating set of double-fed includes: a generator; the rotor-side converter is electrically connected with a rotor of the generator and used for adjusting the frequency of the alternating current output by the rotor to a target frequency, and the target frequency is less than 50 Hz; and the stator side converter is electrically connected with the stator of the generator and is used for adjusting the frequency of the alternating current output by the stator to a target frequency. According to the embodiment of the application, the frequency of the alternating current output by the stator is adjusted to the target frequency smaller than 50Hz by additionally arranging the stator side converter, so that the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency smaller than 50Hz under the condition that a generator in the double-fed asynchronous wind generating set is not required to be redesigned, and the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a power transmission scheme based on power frequency high voltage AC transmission;

fig. 2 is a schematic diagram of a power transmission scheme based on high voltage direct current transmission;

fig. 3 is a schematic structural diagram of a doubly-fed asynchronous wind turbine generator system according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of a power transmission system of a wind generating set according to an embodiment of the present application;

fig. 5 is another schematic structural diagram of a power transmission system of a wind generating set according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of a power transmission system of a wind generating set according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a power transmission system of a wind turbine generator system according to an embodiment of the present application.

Detailed Description

Features and exemplary embodiments of various aspects of the present application will be described in detail below, and in order to make objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are intended to be illustrative only and are not intended to be limiting. It will be apparent to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by illustrating examples thereof.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

Before explaining the technical solutions provided by the embodiments of the present application, in order to facilitate understanding of the embodiments of the present application, the present application first specifically explains the problems existing in the prior art:

as described above, the inventors of the present application have found that there is a problem in the related art that the transmission cost and the modification cost of the wind turbine generator system are high.

In order to solve the problem that the transmission cost and the modification cost of the wind generating set are high, the inventor of the present application firstly researches the transmission line and the transmission mode of the wind generating set in the related art to determine the root cause causing the above technical problems, and the specific research and analysis processes are as follows:

fig. 1 shows a power transmission scheme based on power frequency high voltage ac transmission (HVAC for short). As shown in fig. 1, an offshore wind farm 10 'may include a plurality of wind turbine generators 100', for example, in a power transmission scenario with offshore wind turbine generators. The wind park 100 'may comprise an impeller 101', a generator 102 'and a converter 103'. Illustratively, the Generator 102 'may be a Permanent Magnet Synchronous Generator (PMSG), a Doubly Fed Induction Generator (DFIG), or other type of Generator, for example, the Generator 102' in fig. 1 is illustrated as a PMSG. Driven by wind, the impeller 101 ' starts to rotate and drives the rotor of the generator 102 ' to rotate relative to the stator of the generator 102 ', so as to start generating electricity. In order to ensure that the wind generating set 100 ' can output constant electric energy, the converter 103 ' is generally required to adjust the electric energy output by the generator 102 ' to electric energy with constant voltage amplitude and constant frequency (the frequency is power frequency 50 Hz). The voltage value output by the converter 103' is low, which is not favorable for the transmission of electric energy. Therefore, for efficient transmission of electric energy, it is usually necessary to connect a step-up transformer 200 ' to the output end of the converter 103 ', and step up the voltage output by the converter 103 ' (i.e. the voltage output by the wind turbine generator set 100 ') from a lower voltage value to a higher voltage value, such as from 690V (volts) to 35kV (kilovolts), by the step-up transformer 200 ', such as to obtain an ac power having a voltage value of 35kV and a frequency of 50Hz, i.e. 35kV/50Hz ac power.

Then, the boosted electric energy (e.g. 35kV/50Hz ac) output by each step-up transformer 200 ' is collected by the collecting line 300 ', and the collected electric energy is further boosted to a higher voltage value (e.g. 110kV or 220kV) by the step-up transformer 400 ' in the offshore step-up transformer substation, for example, an ac with a voltage value of 110kV or 220kV and a frequency of 50Hz, that is, an ac with a voltage value of 110kV or 220kV/50Hz is obtained. Then, 110kV or 220kV/50Hz alternating current is transmitted to the onshore substation via the offshore transmission cable 500'. Finally, the alternating current of 110kV or 220kV/50Hz is converted to a target voltage value and with a frequency of 50Hz by a transformer 600 'in a land substation is incorporated into the grid 700'.

The inventor of the present application has found that as the transmission distance increases, the output cost of the HVAC transmission scheme also increases, and when the offshore wind farm is more than a certain distance (e.g. about 80 km), the transmission cost of the HVAC transmission scheme will be higher than that of other transmission schemes.

Fig. 2 shows a transmission scheme based on high voltage direct current transmission (VSC-HVAC for short). As shown in fig. 2, unlike the HVAC transmission scheme shown in fig. 1, the VSC-HVAC transmission scheme shown in fig. 2 further comprises an offshore converter station 800 'and an onshore converter station 900'. It is readily understood that the offshore converter station 800 'is located offshore and the onshore converter station 900' is located onshore. The offshore converter station 800 'is used for converting alternating current (such as 110kV or 220kV/50Hz alternating current) output by the step-up transformer 400' in the offshore step-up transformer station into direct current. The dc power converted by the offshore converter station 800 ' is then transmitted to the onshore converter station 900 ' via the offshore transmission cable 500 '. The onshore converter station 900' again converts the dc power to ac power. That is, the VSC-HVAC power transmission scheme shown in fig. 2 increases the process of converting ac power to dc power and converting dc power to ac power as compared to the HVAC power transmission scheme shown in fig. 1. Therefore, the VSC-HVAC transmission scheme requires the deployment of an offshore converter station 800 'and an onshore converter station 900', which is costly to transmit.

In order to reduce the power transmission cost of the wind generating set, the embodiment of the application provides a low-frequency power transmission scheme or a frequency division power transmission scheme, and the power transmission cost of the wind generating set can be reduced through low-frequency power transmission or frequency division power transmission. However, the inventor of the present application has found another technical problem in the related art, that is, the stator of the doubly-fed asynchronous generator in the related art is designed according to the alternating current outputting 50Hz, and cannot be applied to the low-frequency or frequency-division transmission scenario with the frequency less than 50 Hz. If the stator of the doubly-fed asynchronous generator is suitable for a low-frequency or frequency-division power transmission scene with the frequency less than 50Hz, the doubly-fed asynchronous generator needs to be redesigned, and particularly the stator of the doubly-fed asynchronous generator needs to be redesigned. The generator is used as a core component of the wind turbine generator system, and the redesign of the generator means that the wind turbine generator system needs to be redesigned, so that the modification cost or the design cost of the wind turbine generator system is high.

In view of the above research of the inventor, the embodiment of the present application provides a double-fed asynchronous wind turbine generator system, which can solve the technical problem that the modification cost of the wind turbine generator system is high in the related art.

The technical idea of the embodiment of the application is as follows: the frequency of alternating current output by the stator is adjusted to be less than 50Hz from 50Hz by additionally arranging the stator side converter, so that the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency less than 50Hz under the condition of not redesigning a generator in the double-fed asynchronous wind generating set, and the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

First, a doubly-fed asynchronous wind turbine generator system provided by the embodiment of the present application is described below.

As shown in fig. 3, an embodiment of the present application provides a doubly-fed asynchronous wind turbine generator set 300. So-called "doubly-fed", i.e. both the stator and the rotor of the generator can exchange power with the grid. The stator or stator winding of the doubly-fed asynchronous generator can be directly connected with a power grid, and the rotor or rotor winding can be connected with the power grid through a converter. The frequency, the voltage, the amplitude and the phase of the rotor winding power supply can be automatically adjusted by the converter according to the operation requirement, so that the double-fed asynchronous wind generating set can realize constant-frequency power generation at different rotating speeds, and further the requirements of electric loads and grid connection are met. The double-fed asynchronous wind generating set 300 provided by the embodiment of the application comprises: a generator 301, a rotor-side converter 302, and a stator-side converter 303. The rotor-side converter 302 is electrically connected to the rotor of the generator 301, and adjusts the frequency of the ac power output from the rotor to a target frequency. The stator-side converter 303 is electrically connected to the stator of the generator 301, and adjusts the frequency of the alternating current output from the stator to a target frequency. Wherein the target frequency is less than 50 Hz.

It is to be understood that the rotor-side converter may be a converter disposed on the rotor side and electrically connected to the rotor of the generator 301, and the stator-side converter may be a converter disposed on the stator side and electrically connected to the stator of the generator 301. In practical applications, the Converter may also be called a Frequency Converter or other names, such as the english name Frequency Converter, that is, it is within the scope of the present application to replace the rotor-side Converter and the stator-side Converter with other electronic devices capable of implementing the Frequency conversion function. In the present embodiment, the rotor-side converter 302 and the stator-side converter 303 include, but are not limited to, an AC-AC converter, i.e., an AC-AC converter.

The operation process of the doubly-fed asynchronous wind turbine generator system 300 according to the embodiment of the present application is briefly described below.

With continued reference to fig. 3, according to some embodiments of the present application, the doubly-fed asynchronous wind turbine generator set 300 may further comprise an impeller 304 and a gearbox 305. The impeller 304 drives the gears in the gear box 305 to rotate, so that the conversion of wind energy to mechanical energy is realized. The gear box 305 drives the generator 301 to generate electricity, so that the conversion of mechanical energy to electric energy is realized. The rotor-side converter 302 adjusts the frequency of the alternating current output from the rotor of the generator 301 to be less than a target frequency of 50Hz, and the stator-side converter 303 adjusts the frequency of the alternating current output from the stator of the generator 301 to be less than a target frequency of 50 Hz. Step-up transformer 200 steps up the voltage of the alternating current output from rotor-side converter 302 and stator-side converter 303 from a lower voltage value to a higher voltage value, for example, from 690V to 35kV, obtains an alternating current having a voltage value of 35kV and a frequency of less than 50Hz, and then transmits the alternating current having a voltage value of 35kV and a frequency of less than 50Hz to grid 500.

The double-fed asynchronous wind generating set provided by the embodiment of the application can realize the following technical effects: because the stator of the existing doubly-fed asynchronous generator is designed according to the alternating current of 50Hz, the stator cannot be suitable for a low-frequency or frequency-division power transmission scene with the frequency less than 50 Hz. In the embodiment of the application, the frequency of the alternating current output by the stator is adjusted to be less than 50Hz from 50Hz by additionally arranging the stator-side converter, so that the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency less than 50Hz under the condition of not redesigning a generator in the double-fed asynchronous wind generating set, and the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

Aiming at the problems of high transmission cost and high modification cost of the wind generating set, the embodiment of the application also provides a transmission system of the wind generating set.

As shown in fig. 4, a power transmission system 400 of a wind turbine generator system provided in an embodiment of the present application includes: the double-fed asynchronous wind generating set comprises a double-fed asynchronous wind generating set 410, a first converter 420 and a first boosting transformer 430. The doubly-fed asynchronous wind power generation set 410 comprises a generator 411 and a rotor-side converter 412, wherein the rotor-side converter 412 is electrically connected with a rotor of the generator 411 and is used for adjusting the frequency of alternating current output by the rotor of the generator 411 to a target frequency, and the target frequency is less than 50 Hz. The first converter 420 is electrically connected between the stator of the generator 411 and the grid 500, and is configured to adjust a frequency of the ac power output by the stator of the generator 411 to a target frequency less than 50 Hz. The low-voltage side of the first step-up transformer 430 is electrically connected to the stator of the generator 411 and the rotor-side converter 412, respectively, the high-voltage side of the first step-up transformer 430 is electrically connected to the grid 500, and the first step-up transformer 430 is used to step up the voltage of the alternating current output by the rotor-side converter 302 and the stator of the generator 411 or the first converter 420 from a lower voltage value to a higher voltage value, for example from 690V to 35 kV. The ac power having a higher voltage value and a frequency less than 50Hz boosted by the first step-up transformer 430 is transmitted to the grid 500.

The power transmission system 400 of the wind generating set provided by the embodiment of the application is additionally provided with the first converter, so that the frequency of the alternating current output by the stator is adjusted to be less than 50Hz from 50Hz, and therefore, under the condition that the generator in the double-fed asynchronous wind generating set is not required to be redesigned, the double-fed asynchronous wind generating set can be applicable to a low-frequency or frequency-division power transmission scene with the frequency being less than 50Hz, and the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

In addition, according to the power transmission system 400 of the wind turbine generator system provided by the embodiment of the present application, the rotor-side converter and the first converter are used to adjust the frequency of the alternating current output by the generator to be less than 50Hz, so that on one hand, the maximum power that can be transmitted by the power transmission system of the wind turbine generator system can be improved, that is, the power transmission capability of the power transmission system of the wind turbine generator system is improved; on the other hand, the voltage drop of a power transmission line in a power transmission system of the wind generating set can be reduced, and the voltage stability of the power transmission system is maintained; in another aspect, the loss of the power transmission cable can be reduced, and the service life of the power transmission cable can be prolonged.

With continued reference to fig. 4, according to some embodiments of the present application, optionally, the first converter 420 may be electrically connected between the stator of the generator 411 and the low voltage side of the first step-up transformer 130. That is, the first converter 420 adjusts the frequency of the ac power output from the stator of the generator 411 to a target frequency less than 50Hz, and then the first step-up transformer 430 steps up the ac power output from the first converter 420, so as to obtain an ac power with a higher voltage value (e.g. 35kV) and a frequency less than 50 Hz. In the present embodiment, the rotor-side converter 302 and the first converter 420 include, but are not limited to, an AC-AC converter, i.e., an AC-AC converter.

With continued reference to fig. 4, in some specific embodiments, optionally, a first current transformer 420 may be provided on the stator side. Specifically, an input terminal of the rotor-side converter 412 is electrically connected to a rotor of the generator 411, an input terminal of the first converter 420 is electrically connected to a stator of the generator 411, and an output terminal of the rotor-side converter 412 and an output terminal of the first converter 420 are electrically connected to a low-voltage side of the first step-up transformer 430. The rotor-side converter 412 adjusts the frequency of the alternating current output from the rotor of the generator 411 to a target frequency, and the first converter 420 adjusts the frequency of the alternating current output from the stator of the generator 411 to a target frequency of less than 50 Hz. The first step-up transformer 430 steps up the ac power output by the rotor-side converter 412 and the first converter 420 to obtain an ac power with a relatively high voltage value (e.g. 35kV) and a frequency less than 50 Hz.

In other embodiments, as shown in fig. 5, the first converter 420 may be disposed on the low-voltage side of the first step-up transformer 430. Specifically, an input terminal of the rotor-side converter 412 is electrically connected to a rotor of the generator 411, an input terminal of the first converter 420 is electrically connected to a stator of the generator 411 and an output terminal of the rotor-side converter 412, respectively, and an output terminal of the first converter 420 is electrically connected to a low-voltage side of the first step-up transformer 430. The rotor-side converter 412 adjusts the frequency of the alternating current output from the rotor of the generator 411 to a target frequency, and the first converter 420 adjusts the frequency of the alternating current output from the stator of the generator 411 to a target frequency less than 50 Hz. The first step-up transformer 430 steps up the ac power output by the rotor-side converter 412 and the first converter 420 to obtain an ac power with a relatively high voltage value (e.g. 35kV) and a frequency less than 50 Hz.

Therefore, the frequency of the alternating current output by the stator can be adjusted to the target frequency smaller than 50Hz by the first transformer arranged on the low-voltage side of the first booster transformer, and the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency smaller than 50Hz under the condition that the generator in the double-fed asynchronous wind generating set is not required to be redesigned, so that the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

In other embodiments, as shown in fig. 6, the first converter 420 may be disposed on the high-voltage side of the first step-up transformer 430. Specifically, the first converter 420 is electrically connected between the high-voltage side of the first step-up transformer 430 and the grid 500. The first converter 420 may also adjust the frequency of the alternating current output by the stator of the generator 411 to a target frequency of less than 50 Hz.

Therefore, the frequency of the alternating current output by the stator can be adjusted to the target frequency smaller than 50Hz by the first transformer arranged on the high-voltage side of the first booster transformer, and the double-fed asynchronous wind generating set can be suitable for a low-frequency or frequency-division power transmission scene with the frequency smaller than 50Hz under the condition that the generator in the double-fed asynchronous wind generating set is not required to be redesigned, so that the modification cost or the design cost of the double-fed asynchronous wind generating set is reduced.

According to some embodiments of the present application, the target frequency may optionally be any one of a first frequency range, the first frequency range including 8Hz to 21 Hz. Illustratively, for example, the target frequency may be 50/6Hz, 15Hz, 50/3Hz, 21Hz, or the like.

In some specific embodiments, the target frequency may optionally include 50/3 Hz.

As shown in fig. 7, according to some embodiments of the present application, optionally, power transmission system 400 of the wind turbine generator set may further include a second step-up transformer 710 and a power transmission cable 720, a low-voltage side of second step-up transformer 710 being electrically connected with a high-voltage side of at least one first step-up transformer 430, and a high-voltage side of second step-up transformer 710 being electrically connected with power grid 500 through power transmission cable 720. The second step-up transformer 710 may be used to step up the ac power with a higher voltage value (e.g. 35kV) and a frequency less than 50Hz output by the at least one first step-up transformer 430, for example, to obtain ac power with a higher voltage value (e.g. 110kV or 220kV) and a frequency less than 50 Hz. The power transmission cable 720 transmits the ac power having a higher voltage value (e.g., 110kV or 220kV) and a frequency less than 50Hz, which is output from the second step-up transformer 710, to the power grid 500. It should be noted that in a power transmission scenario of an offshore wind turbine, the second step-up transformer 710 may be disposed in an offshore step-up substation, and the power transmission cable 720 may be an offshore power transmission cable.

With continued reference to fig. 7, according to some embodiments of the present application, the power transmission system 400 of the wind park may optionally further comprise a second converter 730, an input of the second converter 730 being electrically connected to the high voltage side of the second step-up transformer 710 via the power transmission cable 720, an output of the second converter 730 being electrically connected to the grid 500, the second converter 730 being configured to adjust the frequency of the alternating current output by the second step-up transformer 710 from a target frequency to 50 Hz. For example, the second step-up transformer 710 outputs an ac power of 110kV or 220kV and with a frequency less than 50Hz, and the second converter 730 can convert the ac power of 110kV or 220kV and with a frequency less than 50Hz into an ac power of 110kV or 220kV and with a frequency equal to 50 Hz. In the present embodiment, the second converter 730 includes, but is not limited to, an AC-AC converter, i.e., an AC-AC converter.

It should be noted that, in a power transmission scenario of the offshore wind turbine, the second converter 730 may be disposed on the ground, so as to reduce the installation cost of the second converter and improve the installation efficiency of the second converter.

According to some embodiments of the present application, optionally, power transmission system 400 of the wind park may further comprise a first step-down transformer 740 or a third step-up transformer 750, wherein: the high voltage side of first step-down transformer 740 is electrically connected to the high voltage side of second step-up transformer 710 via power transmission cable 720, and the low voltage side of first step-down transformer 740 is electrically connected to grid 500. The low-voltage side of third step-up transformer 750 is electrically connected to the high-voltage side of second step-up transformer 710 via power transmission cable 720, and the high-voltage side of third step-up transformer 750 is electrically connected to grid 500. It should be noted that, in a power transmission scenario of an offshore wind turbine, the first step-down transformer 740 or the third step-up transformer 750 may be disposed on the land.

It is easy to understand that, when it is necessary to step down the ac power transmitted through the power transmission cable 720 (for example, to convert the ac power transmitted through the power transmission cable 720 into electricity for daily life), the first step-down transformer 740 may be provided to step down the ac power transmitted through the power transmission cable 720 by the first step-down transformer 740, so that the ac power output by the power transmission system 400 of the wind turbine generator system is converted into ac power with a desired target voltage value. When the ac power transmitted through power transmission cable 720 needs to be boosted (for example, the ac power transmitted through power transmission cable 720 needs to be transmitted again over a long distance), a third step-up transformer 750 may be provided to boost the ac power transmitted through power transmission cable 720 by third step-up transformer 750, so that the ac power output by power transmission system 400 of the wind turbine generator system is converted into ac power of a desired target voltage value.

It should be noted that, the first step-up transformer 430, the second step-up transformer 710, the third step-up transformer 750, and the first step-down transformer 740 may adopt a star-delta design, a star-star design, or other types of designs, and the embodiment of the present application is not limited.

It should be clear that the embodiments in this specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. For the power transmission system embodiments, reference may be made to the description of the wind park embodiments. The present application is not limited to the particular structures described above and shown in the figures. Those skilled in the art may make various changes, modifications and additions after comprehending the spirit of the present application. Also, a detailed description of known techniques is omitted herein for the sake of brevity.

It will be appreciated by persons skilled in the art that the above embodiments are illustrative and not restrictive. Different features which are present in different embodiments may be combined to advantage. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art upon studying the drawings, the specification, and the claims. In the claims, the term "comprising" does not exclude other means or steps; the word "a" or "an" does not exclude a plurality; the terms "first" and "second" are used to denote a name and not to denote any particular order. Any reference signs in the claims shall not be construed as limiting the scope. The functions of the various parts appearing in the claims may be implemented by a single hardware or software module. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A double-fed asynchronous wind turbine generator system, comprising:

a generator;

a rotor-side converter electrically connected to a rotor of the generator for adjusting a frequency of the alternating current output from the rotor to a target frequency, the target frequency being less than 50 Hz;

a stator-side converter electrically connected to a stator of the generator for adjusting a frequency of the alternating current output from the stator to the target frequency.

2. A power transmission system of a wind turbine generator system, comprising:

the double-fed asynchronous wind generating set comprises a generator and a rotor-side converter, wherein the rotor-side converter is electrically connected with a rotor of the generator and is used for adjusting the frequency of alternating current output by the rotor to a target frequency, and the target frequency is less than 50 Hz;

the low-voltage side of the first boosting transformer is electrically connected with the stator of the generator and the rotor-side converter respectively, and the high-voltage side of the first boosting transformer is electrically connected with a power grid;

the first converter is electrically connected between the stator and the power grid and used for adjusting the frequency of the alternating current output by the stator to a target frequency.

3. The power transmission system of claim 2, wherein the first converter is electrically connected between the stator and the low voltage side of the first step-up transformer.

4. The power transmission system of claim 3, wherein an input of the rotor-side converter is electrically connected to the rotor, an input of the first converter is electrically connected to the stator, and an output of the rotor-side converter and an output of the first converter are both electrically connected to a low voltage side of the first step-up transformer; or,

the input end of the rotor-side converter is electrically connected with the rotor, the input end of the first converter is electrically connected with the output ends of the stator and the rotor-side converter respectively, and the output end of the first converter is electrically connected with the low-voltage side of the first boosting transformer.

5. The power transmission system of claim 2, wherein the first converter is electrically connected between the high voltage side of the first step-up transformer and the grid;

the target frequency is any one frequency in a first frequency range, and the first frequency range comprises 8 Hz-21 Hz.

6. The power transmission system according to any one of claims 2-5, characterized in that the power transmission system further comprises a second step-up transformer, the low-voltage side of which is electrically connected to the high-voltage side of at least one of the first step-up transformers, and a power transmission cable through which the high-voltage side of the second step-up transformer is electrically connected to the grid.

7. The power transmission system of claim 6, further comprising a second converter having an input electrically connected to the high voltage side of the second step-up transformer via the power transmission cable and an output electrically connected to the power grid, the second converter being configured to adjust the frequency of the alternating current output by the second step-up transformer from the target frequency to 50 Hz.

8. The power transmission system of claim 6, further comprising a first step-down transformer or a third step-up transformer, wherein:

the high-voltage side of the first step-down transformer is electrically connected with the high-voltage side of the second step-up transformer through the power transmission cable, and the low-voltage side of the first step-down transformer is electrically connected with the power grid;

the low-voltage side of the third step-up transformer is electrically connected with the high-voltage side of the second step-up transformer through the power transmission cable, and the high-voltage side of the third step-up transformer is electrically connected with the power grid.