CN212392674U

CN212392674U - Direct-current power transmission system of wind generating set

Info

Publication number: CN212392674U
Application number: CN202020793577.3U
Authority: CN
Inventors: 李战龙; 杨有涛; 杨志千
Original assignee: Beijing Goldwind Science and Creation Windpower Equipment Co Ltd
Current assignee: Beijing Goldwind Science and Creation Windpower Equipment Co Ltd
Priority date: 2020-05-13
Filing date: 2020-05-13
Publication date: 2021-01-22
Anticipated expiration: 2030-05-13

Abstract

The application provides a direct current transmission system of a wind generating set, and relates to the field of wind power generation. The direct-current transmission system of the wind generating set comprises a wind generating set array, a direct-current transmission line, a current receiving end converter station, a converter transformer and an alternating-current power grid; the wind generating set array is connected with a direct current transmission line, the direct current transmission line is connected with a receiving end converter station, the receiving end converter station is connected with a converter transformer, and the converter transformer is connected with an alternating current power grid; the wind generating set array comprises N groups of wind generating sets, each group of wind generating sets comprises M wind generating sets connected in series, N is an integer and is not less than 1, and M is an integer and is not less than 2; and under the condition that N is larger than 1, N groups of wind generating sets are connected in parallel to the direct current transmission line. The technical scheme of the application can simplify the structure of the direct-current power transmission system of the wind generating set.

Description

Direct-current power transmission system of wind generating set

Technical Field

The application belongs to the field of wind power generation, and particularly relates to a direct-current power transmission system of a wind generating set.

Background

The flexible direct current transmission is used as a new generation of direct current transmission technology, and has the advantages of capability of independently controlling the reactive power of a converter, good fault ride-through performance, small commutation failure risk, small occupied area and the like, is suitable for various environments, and can be applied to a large number of scenes such as offshore wind power plants and the like.

Fig. 1 is a schematic diagram of an offshore direct current transmission system in the field of wind power generation. As shown in fig. 1, the offshore direct current transmission system includes an alternating current wind turbine generator set matrix 11, an alternating current collection line 12, an offshore booster station 13, an offshore power transmission end converter station 14, a direct current transmission line 15, an offshore power reception end converter station 16, a converter transformer 17, and an alternating current grid 18. The offshore direct current transmission system is complex in structure and high in construction difficulty.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a direct-current power transmission system of a wind generating set, which can simplify the structure of the direct-current power transmission system of the wind generating set.

The embodiment of the application provides a direct-current power transmission system of a wind generating set, which comprises a wind generating set array, a direct-current power transmission line, a receiving end converter station, a converter transformer and an alternating-current power grid;

the wind generating set array is connected with a direct current transmission line, the direct current transmission line is connected with a receiving end converter station, the receiving end converter station is connected with a converter transformer, and the converter transformer is connected with an alternating current power grid;

the wind generating set array comprises N groups of wind generating sets, each group of wind generating sets comprises M wind generating sets connected in series, N is an integer and is not less than 1, and M is an integer and is not less than 2; and under the condition that N is larger than 1, N groups of wind generating sets are connected in parallel to the direct current transmission line.

In some possible embodiments, the dc transmission line includes a positive dc transmission line and a negative dc transmission line; in each group of wind generating sets, the positive terminal port of the bus of the ith wind generating set is connected with the negative terminal port of the bus of the (i-1) th wind generating set, i is an integer and is more than 1 and less than or equal to M; and a bus positive electrode port of the first wind generating set is connected with the positive direct-current transmission line, and a bus negative electrode port of the Mth wind generating set is connected with the negative direct-current transmission line.

In some possible embodiments, the transmission voltage of the direct current transmission line is less than or equal to the sum of the transmission voltages of the M wind generating sets in each group.

In some possible embodiments, the wind generating set comprises a transmission power generation structure, a single-winding transformer, a reactor, a current source converter, an energy storage inductor and a switch module;

the output end of the transmission power generation structure is connected with the input end of the single-winding transformer, the output end of the single-winding transformer is connected with one end of the reactance, the other end of the reactance is connected with the input end of the current source converter, the first output end of the current source converter is connected with one end of the energy storage inductor, the other end of the energy storage inductor is connected with the first input end of the switch module, the second output end of the current source converter is connected with the second input end of the switch module, the first output end of the switch module is a bus positive electrode port of the wind generating set, and the second output end of the switch module is a bus negative electrode port of.

In some possible embodiments, the current source converter comprises three-phase legs, each phase leg comprising an upper leg and a lower leg, the upper and lower legs having power cells.

In some possible embodiments, the power unit includes a backward diode and an IGBT device, a first end of the IGBT device is connected to an anode of the backward diode, a cathode of the backward diode of the upper bridge arm is a first output end of the current source converter, a second end of the IGBT device of the upper bridge arm is an input end of the current source converter, a cathode of the backward diode of the lower bridge arm is an input end of the current source converter, and a second end of the IGBT device of the lower bridge arm is a second output end of the current source converter;

alternatively, the first and second electrodes may be,

the power unit comprises a reverse-resistance IGBT device, the first end of the reverse-resistance IGBT device of the upper bridge arm is the first output end of the current source converter, the second end of the reverse-resistance IGBT device of the upper bridge arm is the input end of the current source converter, the first end of the reverse-resistance IGBT device of the lower bridge arm is the input end of the current source converter, and the second end of the reverse-resistance IGBT device of the lower bridge arm is the second output end of the current source converter;

alternatively, the first and second electrodes may be,

the power unit comprises a thyristor device, wherein the first end of the thyristor device of the upper bridge arm is the first output end of the current source converter, the second end of the thyristor device of the upper bridge arm is the input end of the current source converter, the first end of the thyristor device of the lower bridge arm is the input end of the current source converter, and the second end of the thyristor device of the lower bridge arm is the second output end of the current source converter.

In some possible embodiments, the switch module includes a first switch, a second switch, and a bypass unit, a first end of the first switch is a first input end of the switch module, a second end of the first switch is connected to a first end of the bypass unit, a second end of the first switch is a first output end of the switch module, a first end of the second switch is a second input end of the switch module, a second end of the second switch is connected to a second end of the bypass unit, and a second end of the second switch is a second output end of the switch module.

In some possible embodiments, the switch module includes a four-port switch device, the first input end, the second input end, the first output end and the second output end of the four-port switch device are respectively the first input end, the second input end, the first output end and the second output end of the switch module, the first input end and the first output end of the four-port switch device can be switched on or off, the second input end and the second output end of the four-port switch device can be switched on or off, and the first output end and the second output end of the four-port switch device can be switched on or off.

In some possible embodiments, in a case where the switch module includes a first switch, a second switch, and a bypass unit, an on-off state of the first switch is the same as an on-off state of the second switch, and the on-off state of the first switch is opposite to the on-off state of the bypass unit;

alternatively, the first and second electrodes may be,

under the condition that the switch module comprises the four-port switch device, the on-off state between the first input end of the four-port switch device and the first output end of the four-port switch device is the same as the on-off state between the second input end of the four-port switch device and the second output end of the four-port switch device; the on-off state between the first input terminal of the four-port switching device and the first output terminal of the four-port switching device is opposite to the on-off state between the first output terminal of the four-port switching device and the second output terminal of the four-port switching device.

In some possible embodiments, in case of a fault of the target wind power plant, in the target wind power plant, the first input terminal of the switch module and the first output terminal of the switch module are turned off, the second input terminal of the switch module and the second output terminal of the switch module are turned off, and the first output terminal of the switch module and the second output terminal of the switch module are turned on.

In an embodiment of the application, the wind turbine matrix comprises N groups of wind turbine generators, each group of wind turbine generators comprising M wind turbine generators connected in series. Through M wind generating set series connection, can be under the condition that does not have the booster station, promote the voltage of wind generating set array. According to the direct-current power transmission system of the wind generating set, a booster station and a power transmission end converter station are not needed, the power transmission requirement of the direct-current power transmission system of the wind generating set can be met, and the structure of the direct-current power transmission system of the wind generating set is simplified.

Drawings

The present application may be better understood from the following description of specific embodiments thereof taken in conjunction with the accompanying drawings. Wherein like or similar reference numerals refer to like or similar features.

FIG. 1 is a schematic view of an offshore DC transmission system in the field of wind power generation;

fig. 2 is a schematic structural diagram of a direct-current power transmission system of a wind generating set according to an embodiment of the present application;

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

fig. 4 is a schematic diagram of a single-winding transformer according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of a current source converter in an example of the embodiment of the present application;

fig. 6 is a schematic structural diagram of a current source converter in another example of the embodiment of the present application;

fig. 7 is a schematic structural diagram of a current source converter in another example of the embodiment of the present application;

FIG. 8 is a schematic diagram of a switch module in an example of an embodiment of the present application;

fig. 9 is a schematic diagram of a switch module in another example of the embodiment of the present application.

Detailed Description

Features and exemplary embodiments of various aspects of the present application will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, 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. The present application is in no way limited to any specific configuration and algorithm set forth below, but rather covers any modification, replacement or improvement of elements, components or algorithms without departing from the spirit of the present application. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present application.

The embodiment of the application provides a direct current transmission system of a wind generating set, which can be applied to the field of offshore wind power generation, for example, the offshore flexible direct current transmission is realized. The direct-current transmission system of the wind generating set provided by the embodiment of the application can realize electric energy transmission between the wind generating set and an alternating-current power grid without a booster station and a power transmission end converter station, simplifies the structure of the direct-current transmission system of the wind generating set, and reduces the construction difficulty of an offshore wind power plant.

Fig. 2 is a schematic structural diagram of a direct-current power transmission system of a wind turbine generator system according to an embodiment of the present application. As shown in fig. 2, the dc transmission system of the wind turbine generator system may include a wind turbine generator system array 21, a dc transmission line 22, a receiving end converter station 23, a converter transformer 24 and an ac power grid 25.

The wind generating set array 21 is connected with a direct current transmission line 22. The dc transmission line 22 is connected to a power receiving end converter station 23. The power receiving end converter station 23 is connected to a converter transformer 24. The converter transformer 24 is connected to an ac grid 25.

The wind park array 21 comprises N groups of wind parks. As shown in FIG. 2, each group of wind turbine generators is designated 211. Specifically, the wind generating set in the embodiment of the present application is a direct current wind generating set. Each group of wind generating sets comprises M wind generating sets connected in series. Wherein N is an integer and N is not less than 1, and M is an integer and M is not less than 2. M wind generating sets in each group of wind generating sets are connected in series, so that the voltage at one side of the wind generating set array 21 is increased, and the voltage at one side of the wind generating set array 21 can be increased to meet the requirement of the direct current transmission line 22 without arranging a special booster station. In some examples, the transmission voltage of the dc transmission line 22 is less than or equal to the sum of the transmission voltages of the M wind turbine generators in each group. The Udc multiplied by M is more than or equal to UDC, wherein the Udc is the transmission voltage of each wind generating set and represents the direct-current transmission voltage level of each wind generating set. The UDC is the transmission voltage of the dc transmission line 22 and characterizes the voltage class of the dc transmission line 22. The transmission voltage of the direct current transmission line 22 is less than or equal to the sum of the transmission voltages of the M wind generating sets in each group, so that the direct current transmission system of the wind generating sets can still normally operate under the condition that a certain wind generating set or certain wind generating sets in the wind generating set matrix cannot normally operate, the transmission of electric energy is normally performed, and the stability of the direct current transmission system of the wind generating sets is improved.

In the case of N-1, the group of wind energy installations is connected to the dc power line 22. And under the condition that N is more than 1, N groups of wind generating sets are connected in parallel to the direct current transmission line 22. The N groups of wind generating sets are connected in parallel, so that the current transmitted to the direct current transmission line 22 by the wind generating set array 21 can be increased, the power of the wind generating set array 21 is improved, and the capacity grade of a direct current transmission system of the wind generating sets is improved.

It should be noted that the specific values of M and N may be set according to the requirement of the dc transmission system of the wind turbine generator system on the capacity level, the voltage and the current that can be generated by the wind turbine generator system, and the setting is not limited herein.

In an embodiment of the application, the wind turbine matrix comprises N groups of wind turbine generators, each group of wind turbine generators comprising M wind turbine generators connected in series. By connecting M wind turbine generators in series, the voltage of the wind turbine generator system array 21 can be boosted without a booster station. According to the direct-current power transmission system of the wind generating set, a booster station and a power transmission end converter station are not needed, the power transmission requirement of the direct-current power transmission system of the wind generating set can be met, and the structure of the direct-current power transmission system of the wind generating set is simplified. The simplified direct-current power transmission system of the wind generating set also reduces the construction cost, the maintenance cost and the like.

Under the condition that the wind generating set direct current transmission system is applied to the field of offshore wind power generation, the wind generating set direct current transmission system in the embodiment of the application also greatly reduces the difficulty of offshore construction.

Each wind generating set is provided with a bus positive terminal and a bus negative terminal. The dc transmission line 22 in the above embodiment may include a positive dc transmission line 221 and a negative dc transmission line 222. In some examples, the dc power transmission line 22 may be specifically a dc bus, the positive dc power transmission line 221 may be specifically a positive dc bus, and the negative dc power transmission line 222 may be specifically a negative dc bus. As shown in fig. 2, in each group of wind turbine generators, the positive bus port of the first wind turbine generator is connected to the positive dc transmission line 221, and the negative bus port of the mth wind turbine generator is connected to the negative dc transmission line 222. In each group of wind generating sets, the positive port of the bus of the ith wind generating set is connected with the negative port of the bus of the (i-1) th wind generating set. Wherein i is an integer and is more than 1 and less than or equal to M.

Fig. 3 is a schematic structural diagram of a wind turbine generator system according to an embodiment of the present application. As shown in fig. 3, the wind turbine may include a transmission power generation structure, a single winding transformer 34, a reactor 35, a current source converter 36, an energy storage inductor L1, and a switch module 37.

The output of the drive generation structure is connected to the input of a single winding transformer 34. The output of the single-winding transformer 34 is connected to one end of a reactance 35. The other end of the reactance 35 is connected to the input of a current source converter 36. A first output of the current source converter 36 is connected to one end of the energy storage inductor L1. The other end of the energy storage inductor L1 is connected to a first input terminal of the switching module 37. A second output of the current source converter 36 is connected to a second input of the switching module 37. The first output end of the switch module 37 is a bus positive terminal of the wind turbine generator system. A second output of the switch module 37 is a bus negative port of the wind turbine generator set.

The transmission power generation structure may include blades 31, a gear box 32, a generator 33, and the like. Wherein the gearbox 32 and the generator 33 constitute the key components of the semi-direct drive transmission. The blades 31 rotate to drive the gearbox 32 and thus the generator 33 to convert wind energy into electrical energy.

The single-winding transformer 34 includes a primary winding and a secondary winding. The primary winding is connected with the low-voltage side of the wind generating set, and the secondary winding is connected with the high-voltage side of the wind generating set. The voltage isolation capability of the single-winding transformer 34 is utilized to improve the voltage level of the secondary winding, so that the output power of a single wind generating set is improved, the number of the wind generating sets connected in series is reduced on the basis of ensuring that the output power of the wind generating set matrix meets the direct-current power transmission system of the wind generating set, and the structure of the direct-current power transmission system of the wind generating set is further simplified.

Fig. 4 is a schematic diagram of a single-winding transformer according to an embodiment of the present application. As shown in fig. 4, the single-winding transformer 34 includes a primary winding and a secondary winding. The primary winding is connected in a star shape, and the secondary winding is connected in a triangular shape.

The current source converter 36 includes three phase legs, each of which includes an upper leg and a lower leg. The upper bridge arm and the lower bridge arm are provided with power units.

In some examples, fig. 5 is a schematic structural diagram of a current source converter in an example of an embodiment of the present application. The current source transformer 36a shown in fig. 5 is an embodiment of the current source transformer 36 shown in fig. 3. As shown in fig. 5, the power cell may include a reverse diode and an Insulated Gate Bipolar Transistor (IGBT) device. For ease of labeling, the three-phase legs include backward diodes D1-D6 and IGBT devices T1-T6.

The first terminal of the IGBT device is connected to the anode of the backward diode. The cathode of the reverse diode of the upper bridge arm is the first output end of the current source converter 36a, and the second end of the IGBT device of the upper bridge arm is the input end of the current source converter 36 a. The cathode of the reverse diode of the lower bridge arm is the input end of the current source converter 36a, and the second end of the IGBT device of the lower bridge arm is the second output end of the current source converter 36 a. In the same phase bridge arm, the second end of the IGBT device of the upper bridge arm is connected with the cathode of the reverse diode of the lower bridge arm. And the cathodes of the reverse diodes in the upper bridge arm of the three-phase bridge arm are connected with each other, and the second ends of the IGBT devices in the lower bridge arm of the three-phase bridge arm are connected with each other. Each phase leg has one input of a current source converter 36 a. As shown in fig. 5, a1 is the input terminal of phase a of the current source converter 36a in the first phase leg, B1 is the input terminal of phase B of the current source converter 36a in the second phase leg, and C1 is the input terminal of phase C of the current source converter 36a in the third phase leg.

Specifically, the first terminal of the IGBT device is an emitter of the IGBT device, and the second terminal of the IGBT device is a collector of the IGBT device.

In other examples, fig. 6 is a schematic structural diagram of a current source converter in another example of the embodiment of the present application. The current source transformer 36b shown in fig. 6 is another embodiment of the current source transformer 36 shown in fig. 3. As shown in fig. 6, the power cell includes a reverse blocking type IGBT device. For convenience of indication, reverse-blocking type IGBT devices T7 to T12 are included on the three-phase arm.

The first end of the reverse-blocking type IGBT device of the upper arm is the first output end of the current source converter 36b, and the second end of the reverse-blocking type IGBT device of the upper arm is the input end of the current source converter 36 b. The first end of the reverse-blocking type IGBT device of the lower bridge arm is an input end of the current source converter 36b, and the second end of the reverse-blocking type IGBT device of the lower bridge arm is a second output end of the current source converter 36 b. In the same phase of bridge arm, the second end of the reverse-resistance IGBT device of the upper bridge arm is connected with the first end of the reverse-resistance IGBT device of the lower bridge arm. The first ends of the reverse-resistance IGBT devices in the upper bridge arms of the three-phase bridge arms are connected with each other, and the second ends of the reverse-resistance IGBT devices in the lower bridge arms of the three-phase bridge arms are connected with each other. Each phase leg has one input of a current source converter 36 b. As shown in fig. 6, a1 is the input terminal of phase a of the current source converter 36B in the first phase arm, B1 is the input terminal of phase B of the current source converter 36B in the second phase arm, and C1 is the input terminal of phase C of the current source converter 36B in the third phase arm.

Specifically, the reverse blocking type IGBT device is equivalent to integrating an equivalent diode at the emitter of the IGBT device. For convenience of explanation, the equivalent diode is shown in the reverse blocking IGBT device in fig. 6, but it should be noted that the equivalent diode is equivalently generated in the process of manufacturing the reverse blocking IGBT device, and is not connected in series with a diode. The first end of the reverse-resistance type IGBT device is an emitting electrode of the reverse-resistance type IGBT device, and the second end of the reverse-resistance type IGBT device is a collecting electrode of the reverse-resistance type IGBT device.

In still other examples, fig. 7 is a schematic structural diagram of a current source converter in still another example of the embodiment of the present application. The current source transformer 36c shown in fig. 7 is another embodiment of the current source transformer 36 shown in fig. 3. As shown in fig. 7, the power cell includes a thyristor device. For ease of illustration, the three-phase legs include thyristor devices T13 through T18.

The first end of the thyristor device of the upper bridge arm is the first output end of the current source converter 36c, and the second end of the thyristor device of the upper bridge arm is the input end of the current source converter 36 c. The first end of the thyristor device of the lower bridge arm is an input end of the current source converter 36c, and the second end of the thyristor device of the lower bridge arm is a second output end of the current source converter 36 c. In the same phase bridge arm, the second end of the thyristor device of the upper bridge arm is connected with the first end of the thyristor of the lower bridge arm. The first ends of the thyristor devices in the upper bridge arm of the three-phase bridge arm are connected with each other, and the second ends of the thyristor devices in the lower bridge arm of the three-phase bridge arm are connected with each other. Each phase leg has one input of a current source converter 36 c. As shown in fig. 7, a1 is the input terminal of phase a of the current source transformer 36C in the first phase leg, B1 is the input terminal of phase B of the current source transformer 36C in the second phase leg, and C1 is the input terminal of phase C of the current source transformer 36C in the third phase leg.

Specifically, the first end of the thyristor device is a cathode of the thyristor device, and the second end of the thyristor device is an anode of the thyristor device.

The switch module 37 may be used to control whether the wind turbine generator set in which the switch module 37 is located is in use. In particular, the switch module 37 may include a first input terminal X1, a second input terminal X2, a first output terminal Y1, and a second output terminal Y2. Whether the wind generating set where the switch module 37 is located is put into use or not is controlled by controlling the on-off state between the first input end X1 and the first output end Y1, the on-off state between the second input end X2 and the second output end Y2, and the on-off state between the first output end Y1 and the second output end Y2.

In the case of a fault of the target wind generating set, in the target wind generating set, the first input end X1 of the switch module 37 and the first output end Y1 of the switch module 37 are turned off, the second input end X2 of the switch module 37 and the second output end Y2 of the switch module 37 are turned off, and the first output end Y1 of the switch module 37 and the second output end Y2 of the switch module 37 are turned on, so that the target wind generating set is switched out of the direct current transmission system of the wind generating set, and the normal operation of the direct current transmission system of the wind generating set is not affected. After the first output terminal Y1 of the switch module 37 and the second output terminal Y2 of the switch module 37 are turned on, a zero voltage state and a zero current state are respectively between the first input terminal X1 of the switch module 37 and the first output terminal Y1 of the switch module 37, and between the second input terminal X2 of the switch module 37 and the second output terminal Y2 of the switch module 37, so that the turn-off between the first input terminal X1 of the switch module 37 and the first output terminal Y1 of the switch module 37, and the turn-off between the second input terminal X2 of the switch module 37 and the second output terminal Y2 of the switch module 37 are safer. The grounding between the first input end X1 of the switch module 37 and the first output end Y1 of the switch module 37, and the grounding between the second input end X2 of the switch module 37 and the second output end Y2 of the switch module 37 can be further performed, so that the wind generating set can be safely repaired and maintained.

In the wind generating set capable of normally operating, the first input end X1 of the switch module 37 is connected with the first output end Y1 of the switch module 37, the second input end X2 of the switch module 37 is connected with the second output end Y2 of the switch module 37, and the first output end Y1 of the switch module 37 is connected with the second output end Y2 of the switch module 37, so that the wind generating set capable of normally operating is put into a direct current transmission system of the wind generating set, and the wind generating set is enabled to normally operate. For example, in the case that the fault of the wind turbine generator set with the fault has been repaired, the conduction between the first input terminal X1 of the switch module 37 and the first output terminal Y1 of the switch module 37, the conduction between the second input terminal X2 of the switch module 37 and the second output terminal Y2 of the switch module 37, and the disconnection between the first output terminal Y1 of the switch module 37 and the second output terminal Y2 of the switch module 37 in the wind turbine generator set with the fault repaired can be controlled, so that the wind turbine generator set with the fault repaired is put into the wind turbine generator set direct current transmission system for continuous use.

In some examples, fig. 8 is a schematic diagram of a switch module in an example of an embodiment of the present application. The switch module 37a shown in fig. 8 is an embodiment of the switch module 37 shown in fig. 3. As shown in fig. 8, the switch module 37a includes a first switch 371, a second switch 372, and a bypass unit 373.

The first terminal of the first switch 371 is a first input terminal X1 of the switch module 37a, the second terminal of the first switch 371 is connected to the first terminal of the bypass unit 373, and the second terminal of the first switch 371 is a first output terminal Y1 of the switch module 37 a. The first terminal of the second switch 372 is the second input terminal X2 of the switch module 37a, the second terminal of the second switch 372 is connected to the second terminal of the bypass unit 373, and the second terminal of the second switch 372 is the second output terminal Y2 of the switch module 37 a.

The first switch 371 and the second switch 372 may be implemented by an isolation switch, and the bypass unit 373 may be implemented by a switching device, but the specific structures of the first switch 371, the second switch 372, and the bypass unit 373 are not limited herein.

Correspondingly, the on-off state of the first switch 371 is the same as the on-off state of the second switch 372, and the on-off state of the first switch 371 is opposite to the on-off state of the bypass unit 373. For example, the first switch 371 is turned on, the second switch 372 is turned on, and the bypass unit 373 is turned off. Alternatively, the first switch 371 is turned off, the second switch 372 is turned off, and the bypass unit 373 is turned on.

In the wind generating set with the fault, the first switch 371 is turned off, the second switch 372 is turned off, and the bypass unit 373 is turned on, so that the wind generating set with the fault is switched out of the direct current transmission system of the wind generating set.

In the wind generating set capable of normal operation, the first switch 371 is turned on, the second switch 372 is turned on, and the bypass unit 373 is turned off, so that the wind generating set capable of normal operation is put into the direct current transmission system of the wind generating set.

In other examples, switching module 37 may include a four-port switching device. The first input end, the second input end, the first output end and the second output end of the four-port switching device are respectively a first input end X1, a second input end X2, a first output end Y1 and a second output end Y2 of the switching module 37. The first input end of the four-port switching device and the first output end of the four-port switching device can be connected or disconnected, the second input end of the four-port switching device and the second output end of the four-port switching device can be connected or disconnected, and the first output end of the four-port switching device and the second output end of the four-port switching device can be connected or disconnected.

Correspondingly, the on-off state between the first input end of the four-port switching device and the first output end of the four-port switching device is the same as the on-off state between the second input end of the four-port switching device and the second output end of the four-port switching device. The on-off state between the first input terminal of the four-port switching device and the first output terminal of the four-port switching device is opposite to the on-off state between the first output terminal of the four-port switching device and the second output terminal of the four-port switching device. For example, if the first input terminal of the four-port switching device and the first output terminal of the four-port switching device are turned on, and the second input terminal of the four-port switching device and the second output terminal of the four-port switching device are turned on, the first output terminal of the four-port switching device and the second output terminal of the four-port switching device are turned off. Or, the first input end of the four-port switching device and the first output end of the four-port switching device are turned off, the second input end of the four-port switching device and the second output end of the four-port switching device are turned off, and the first output end of the four-port switching device and the second output end of the four-port switching device are turned on.

In the wind generating set with the fault, the first input end of the four-port switching device and the first output end of the four-port switching device are switched off, the second input end of the four-port switching device and the second output end of the four-port switching device are switched off, and the first output end of the four-port switching device and the second output end of the four-port switching device are switched on, so that the wind generating set with the fault is switched into a direct current transmission system of the wind generating set.

In the wind generating set capable of normally operating, a first input end of the four-port switching device is connected with a first output end of the four-port switching device, a second input end of the four-port switching device is connected with a second output end of the four-port switching device, and the first output end of the four-port switching device is connected with the second output end of the four-port switching device, so that the wind generating set capable of normally operating is put into a direct-current transmission system of the wind generating set.

The four-port switching device including three switching ports will be described as an example. Fig. 9 is a schematic diagram of a switch module in another example of the embodiment of the present application. Switch module 37b shown in fig. 9 is another embodiment of switch module 37 shown in fig. 3. As shown in fig. 9, the switch module 37b includes a first switch port 374, a second switch port 375, and a third switch port 376.

The first switch port 374 of the four-port switching device is located between the first input terminal and the first output terminal of the four-port switching device. The second switch port 375 of the four-port switching device is located between the second input terminal and the second output terminal of the four-port switching device. The third switch 376 of the four-port switching device is located between the first and second output terminals of the four-port switching device.

The first and second switch ports 374 and 375 are switched on and off in the same manner, and the third switch port 376 is switched on and off in the opposite manner to the first switch port 374. For example, when the first switch port 374 is turned on, the second switch port 375 is turned on, and the third switch port 376 is turned off. Alternatively, the first switch port 374 is turned off, the second switch port 375 is turned off, and the third switch port 376 is turned on.

In the wind generating set with the fault, the first switch opening 374 is turned off, the second switch opening 375 is turned off, and the third switch opening 376 is turned on, so that the wind generating set with the fault is cut out of the direct current transmission system of the wind generating set.

In the wind generating set capable of normally operating, the first switch opening 374 is turned on, the second switch opening 375 is turned on, and the third switch opening 376 is turned off, so that the wind generating set capable of normally operating is put into a direct current transmission system of the wind generating set.

The present application may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, the present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

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 direct-current transmission system of a wind generating set is characterized by comprising a wind generating set array, a direct-current transmission line, a receiving end converter station, a converter transformer and an alternating-current power grid;

the wind generating set array is connected with the direct current transmission line, the direct current transmission line is connected with the power receiving end converter station, the power receiving end converter station is connected with the converter transformer, and the converter transformer is connected with the alternating current power grid;

the wind generating set array comprises N groups of wind generating sets, each group of wind generating sets comprises M wind generating sets connected in series, N is an integer and is not less than 1, and M is an integer and is not less than 2; under the condition that N is larger than 1, N groups of wind generating sets are connected in parallel to the direct current transmission line;

the transmission voltage of the direct current transmission line is less than or equal to the sum of the transmission voltages of the M wind generating sets in each group of wind generating sets, the transmission voltage of each wind generating set represents the direct current transmission voltage grade of each wind generating set, and the transmission voltage of the direct current transmission line represents the voltage grade of the direct current transmission line.

2. The wind generating set direct current transmission system of claim 1, wherein the direct current transmission line comprises a positive direct current transmission line and a negative direct current transmission line;

in each group of wind generating sets, the positive terminal port of the bus of the ith wind generating set is connected with the negative terminal port of the bus of the (i-1) th wind generating set, i is an integer and is more than 1 and less than or equal to M;

and a bus positive port of the first wind generating set is connected with the positive direct-current transmission line, and a bus negative port of the Mth wind generating set is connected with the negative direct-current transmission line.

3. The wind-driven generator set direct-current transmission system of claim 1, wherein the wind-driven generator set comprises a transmission power generation structure, a single-winding transformer, a reactor, a current source converter, an energy storage inductor and a switch module;

the output end of the transmission power generation structure is connected with the input end of the single-winding transformer, the output end of the single-winding transformer is connected with one end of the reactance, the other end of the reactance is connected with the input end of the current source converter, the first output end of the current source converter is connected with one end of the energy storage inductor, the other end of the energy storage inductor is connected with the first input end of the switch module, the second output end of the current source converter is connected with the second input end of the switch module, the first output end of the switch module is a bus positive electrode port of the wind generating set, and the second output end of the switch module is a bus negative electrode port of the wind generating set.

4. The wind turbine direct current transmission system of claim 3, wherein the current source converter comprises three phase legs, each phase leg comprising an upper leg and a lower leg, the upper and lower legs having power cells.

5. The wind turbine generator system DC transmission system of claim 4,

the power unit comprises a reverse diode and an IGBT device, wherein a first end of the IGBT device is connected with an anode of the reverse diode, a cathode of the reverse diode of the upper bridge arm is a first output end of the current source converter, a second end of the IGBT device of the upper bridge arm is an input end of the current source converter, a cathode of the reverse diode of the lower bridge arm is an input end of the current source converter, and a second end of the IGBT device of the lower bridge arm is a second output end of the current source converter;

alternatively, the first and second electrodes may be,

the power unit comprises a reverse-resistance IGBT device, a first end of the reverse-resistance IGBT device of the upper bridge arm is a first output end of the current source converter, a second end of the reverse-resistance IGBT device of the upper bridge arm is an input end of the current source converter, a first end of the reverse-resistance IGBT device of the lower bridge arm is an input end of the current source converter, and a second end of the reverse-resistance IGBT device of the lower bridge arm is a second output end of the current source converter;

alternatively, the first and second electrodes may be,

the power unit comprises a thyristor device, a first end of the thyristor device of the upper bridge arm is a first output end of the current source converter, a second end of the thyristor device of the upper bridge arm is an input end of the current source converter, a first end of the thyristor device of the lower bridge arm is an input end of the current source converter, and a second end of the thyristor device of the lower bridge arm is a second output end of the current source converter.

6. The wind turbine generator system DC transmission system of claim 3,

the switch module comprises a first switch, a second switch and a bypass unit, wherein a first end of the first switch is a first input end of the switch module, a second end of the first switch is connected with a first end of the bypass unit, a second end of the first switch is a first output end of the switch module, a first end of the second switch is a second input end of the switch module, a second end of the second switch is connected with a second end of the bypass unit, and a second end of the second switch is a second output end of the switch module.

7. The wind turbine generator system DC transmission system of claim 3,

the switch module includes four port switch devices, four port switch device's first input, second input, first output and second output do respectively switch module's first input, second input, first output and second output, four port switch device's first input with can switch on or turn-off between four port switch device's the first output, four port switch device's second input with can switch on or turn-off between four port switch device's the second output, four port switch device's first output with can switch on or turn-off between four port switch device's the second output.

8. The wind power generation set DC power transmission system of claim 6 or 7,

under the condition that the switch module comprises a first switch, a second switch and a bypass unit, the on-off state of the first switch is the same as that of the second switch, and the on-off state of the first switch is opposite to that of the bypass unit;

alternatively, the first and second electrodes may be,

under the condition that the switch module comprises a four-port switch device, the on-off state between the first input end of the four-port switch device and the first output end of the four-port switch device is the same as the on-off state between the second input end of the four-port switch device and the second output end of the four-port switch device; the on-off state between the first input end of the four-port switching device and the first output end of the four-port switching device is opposite to the on-off state between the first output end of the four-port switching device and the second output end of the four-port switching device.

9. The wind turbine generator system DC transmission system of claim 3,

under the condition that a target wind generating set breaks down, in the target wind generating set, a first input end of the switch module and a first output end of the switch module are switched off, a second input end of the switch module and a second output end of the switch module are switched off, and the first output end of the switch module and the second output end of the switch module are switched on.