Wind turbine transmission system

Abstract

This application discloses a wind turbine power transmission system, belonging to the field of wind power generation. The wind turbine power transmission system comprises an AC wind turbine matrix, AC transmission lines, a converter station, a converter transformer, and an AC power grid, all electrically connected in sequence. The AC transmission lines are used to transmit low-frequency AC power or fractional-frequency AC power, which has a frequency lower than the power frequency. Embodiments of this application can simplify the structure of the power transmission system.

Description

Technical Field

[0001] The present application relates to the field of wind power generation, and in particular to a wind turbine generator system. Background Art

[0002] The electricity generated by wind turbines can be transmitted to the AC grid via a transmission system. This system can include multiple components to achieve functions such as voltage boosting and current conversion. Figure 1 This is a structural diagram of a current power transmission system. Figure 1 As shown, the transmission system may include a wind turbine 11, an AC collection line 12, a step-up transformer 13, a sending-end converter station 14, a DC transmission line 15, a receiving-end converter station 16, a converter transformer 17, and an AC grid 18. In other words, at least two converter stations are required in the transmission system. In multi-terminal transmission scenarios, even more converter stations are required, increasing the complexity of the transmission system structure. Summary of the Invention

[0003] The embodiments of the present application provide a wind turbine generator set power transmission system, which can simplify the structure of the power transmission system.

[0004] An embodiment of the present application provides a wind turbine power transmission system, comprising an AC wind turbine matrix, an AC transmission line, a converter station, a converter transformer, and an AC power grid electrically connected in sequence; the AC transmission line is used to transmit low-frequency AC power or fractional-frequency AC power, and low-frequency AC power and fractional-frequency AC power are AC power with a frequency lower than the industrial frequency.

[0005] In some possible embodiments, the AC transmission line includes a first AC transmission line and a second AC transmission line; a first end of the AC wind turbine generator matrix is ​​connected to the first AC transmission line, and a second end of the AC wind turbine generator matrix is ​​connected to the second AC transmission line; and the converter station includes a modular multilevel converter.

[0006] In some possible embodiments, the AC wind turbine generator matrix includes N1 groups of AC wind turbine generators, and each group of AC wind turbine generator matrix includes M1 AC wind turbine generators, where N1 and M1 are positive integers; when N1>1, the N1 groups of AC wind turbine generators are connected in parallel; when M1>1, the M1 AC wind turbine generators in each group are connected in series.

[0007] In some possible embodiments, the AC transmission line includes a first-phase AC transmission line, a second-phase AC transmission line, and a third-phase AC transmission line; the first-phase port of the AC wind turbine generator matrix is ​​connected to the first-phase AC transmission line, the second-phase port of the AC wind turbine generator matrix is ​​connected to the second-phase AC transmission line, and the third-phase port of the AC wind turbine generator matrix is ​​connected to the third-phase AC transmission line; and the converter station includes a modular multilevel matrix converter.

[0008] In some possible embodiments, the AC wind turbine generator matrix includes three groups of AC wind turbine generators, each group of AC wind turbine generator matrix includes M2 AC wind turbine generators, and M2 is a positive integer; in each group of AC wind turbine generators, the first output port of the first AC wind turbine generator is respectively connected to the corresponding single-phase AC transmission line, and the second output port of the last AC wind turbine generator in each group of AC wind turbine generators is connected; when M2>1, the M2 AC wind turbine generators in each group of AC wind turbine generators are connected in series.

[0009] In some possible embodiments, the AC wind turbine generator array matrix includes M3 AC wind turbine generator arrays, where M3 is a positive integer; each AC wind turbine generator array includes a three-phase simplified matrix converter, and the input port of the first-phase simplified matrix converter, the input port of the second-phase simplified matrix converter, and the input port of the third-phase simplified matrix converter in each AC wind turbine generator array are connected; when M3>1, the first-phase simplified matrix converters in each AC wind turbine generator array are connected in series, the second-phase simplified matrix converters in each AC wind turbine generator array are connected in series, and the AC wind turbine generator arrays are connected in series. The third-phase simplified matrix converters in the AC wind turbine generator sets are connected in series; in the first AC wind turbine generator set, the first output port of the first-phase simplified matrix converter is connected to the first-phase AC transmission line, the first output port of the second-phase simplified matrix converter is connected to the second-phase AC transmission line, and the first output port of the third-phase simplified matrix converter is connected to the third-phase AC transmission line; in the last AC wind turbine generator set, the second output port of the first-phase simplified matrix converter, the second output port of the second-phase simplified matrix converter, and the second output port of the third-phase simplified matrix converter are connected.

[0010] In some possible embodiments, each AC wind turbine generator set includes blades, a gearbox, a generator, a single-winding transformer, a simplified matrix converter, a first switch unit, a second switch unit, and a bypass switch unit. The first switch unit is located between the first output port of the simplified matrix converter and the first output port of the AC wind turbine generator set, the second switch unit is located between the second output port of the simplified matrix converter and the second output port of the AC wind turbine generator set, and the bypass switch unit is located between the first output port of the AC wind turbine generator set and the second output port of the AC wind turbine generator set.

[0011] In some possible embodiments, the on-off states of the first switch unit and the second switch unit are the same, and the on-off states of the first switch unit and the bypass switch unit are opposite.

[0012] In some possible embodiments, each AC wind turbine generator set further includes blades, a gearbox, a generator, and a single-winding transformer. In each AC wind turbine generator set, the single-winding transformer is respectively connected to the input port of the first-phase simplified matrix converter, the input port of the second-phase simplified matrix converter, and the input port of the third-phase simplified matrix converter.

[0013] In some possible embodiments, the modular multilevel matrix converter includes three bridge arm power units, each bridge arm power unit includes a three-phase bridge arm power subunit; in each bridge arm power unit, the first port of the first-phase bridge arm power subunit is connected to the first-phase output port of the modular multilevel matrix converter through an inductor device, the first port of the second-phase bridge arm power subunit is connected to the second-phase output port of the modular multilevel matrix converter through an inductor device, the first port of the third-phase bridge arm power subunit is connected to the third-phase output port of the modular multilevel matrix converter through an inductor device, the second port of the first-phase bridge arm power subunit, the second port of the second-phase bridge arm power subunit, and the second port of the third-phase bridge arm power subunit are connected and connected to the corresponding single-phase AC transmission line.

[0014] An embodiment of the present application provides a wind turbine power transmission system comprising an AC wind turbine matrix, AC transmission lines, a converter station, a converter transformer, and an AC power grid, all electrically connected in sequence. The AC transmission lines transmit low-frequency AC power or fractional-frequency AC power. The low frequencies of low-frequency AC power and fractional-frequency AC power improve power transmission quality, enabling a single converter station in the wind turbine power transmission system to meet power transmission requirements, thereby simplifying the structure of the power transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 This is a structural diagram of a current power transmission system;

[0017] Figure 2 A schematic structural diagram of an embodiment of a wind turbine power transmission system provided in this application;

[0018] Figure 3 Schematic diagram of an example of a wind turbine generator transmission system in an embodiment of the present application;

[0019] Figure 4 This is a schematic structural diagram of an example of a power unit in an embodiment of the present application;

[0020] Figure 5 This is a structural diagram of an example of an AC wind turbine generator set in an embodiment of the present application;

[0021] Figure 6 This is a structural diagram of an example of a simplified matrix converter in an embodiment of the present application;

[0022] Figure 7 is a structural diagram of another example of a wind turbine generator transmission system in an embodiment of the present application;

[0023] Figure 8 A schematic structural diagram of an example of a modular multi-level matrix converter provided in an embodiment of the present application;

[0024] Figure 9 This is a schematic structural diagram of an example of a power module in an embodiment of the present application;

[0025] Figure 10 This is a structural diagram of another example of a wind turbine generator transmission system in an embodiment of the present application;

[0026] Figure 11 This is a structural diagram of another example of an AC wind turbine generator set in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating the examples of the present application.

[0028] The electricity generated by wind turbines can be transmitted to the AC grid through the transmission system. However, due to the distribution of wind resources, wind turbines are often installed in locations far away from the AC grid. Figure 1 As shown, the electric energy generated by the wind turbine 11 can be transmitted to the AC grid 18 through the AC collection line 12, the step-up transformer 13, the sending-end converter station 14, the DC transmission line 15, the receiving-end converter station 16, and the converter transformer 17. The transmission system requires at least two converter stations to achieve the transmission of electric energy. In a multi-terminal transmission scenario, such as when wind turbines located in different areas transmit electricity to the AC grid, more converter stations are required. The increase in the number of converter stations makes the transmission system structure more complex and increases the cost required to build and maintain the transmission system. This is especially true when the wind turbine is far away from the AC grid, such as in an offshore wind power generation scenario, where the wind turbine 11, the AC collection line 12, the step-up transformer 13, the sending-end converter station 14, the DC transmission line 15, and the receiving-end converter station 16 are located at sea, and the converter transformer 17 and the AC grid 18 are located on land. This makes the transmission system structure more complex and the cost required to build and maintain the transmission system higher.

[0029] The present application provides a wind turbine power transmission system that can reduce the number of required converter stations, thereby simplifying the structure of the power transmission system and reducing the cost required for construction and maintenance of the power transmission system.

[0030] Figure 2 This is a schematic diagram of the structure of an embodiment of the wind turbine power transmission system provided by this application. Figure 2 As shown, the wind turbine power transmission system may include an AC wind turbine matrix 21, an AC transmission line 22, a converter station 23, a converter transformer 24 and an AC power grid 25 that are electrically connected in sequence.

[0031] Specifically, the AC wind turbine matrix 21 is connected to the AC transmission line 22, which is connected to the converter station 23. The converter station 23 is connected to the converter transformer 24, which is connected to the AC power grid 25. The AC wind turbine matrix 21 may include at least one AC wind turbine 221. If the AC wind turbine matrix 21 includes two or more AC wind turbines 221, the specific connection of the two or more AC wind turbines 221 is not limited herein. The AC wind turbines 221 generate AC power. The AC power generated by the AC wind turbines 221 is transmitted to the converter station 23 via the AC transmission line 22. The converter station 23 performs AC-to-AC conversion, specifically, converting the frequency and voltage of the AC power. The converter transformer 24 performs voltage conversion on the AC power and transmits the converted AC power to the AC power grid 25.

[0032] The AC transmission line 22 is used to transmit low-frequency AC power or fractional-frequency AC power, that is, the AC transmission line 22 transmits low-frequency AC power or fractional-frequency AC power. Low-frequency AC power and fractional-frequency AC power are AC power with a frequency lower than the power frequency, that is, the frequency of low-frequency AC power is lower than the power frequency, and the frequency of fractional-frequency AC power is lower than the power frequency. The frequencies of low-frequency AC power and fractional-frequency AC power can be set according to the working scenario and working requirements, and are not limited here. For example, the frequency of low-frequency AC power and the frequency of power-frequency AC power can be 1 / 3 of the power frequency. By reducing the transmission frequency in the AC transmission line 22, the reactance of the transmission line can be reduced, thereby improving the transmission quality while meeting the requirements of long-distance power transmission.

[0033] In the embodiment of the present application, the wind turbine transmission system includes an AC wind turbine matrix 21, an AC transmission line 22, a converter station 23, a converter transformer 24, and an AC grid 25, which are electrically connected in sequence. The AC transmission line 22 transmits low-frequency AC power or fractional-frequency AC power. The low frequencies of low-frequency AC power and fractional-frequency AC power improve power transmission quality, allowing a single converter station 23 in the wind turbine transmission system to meet power transmission requirements. This simplifies the transmission system structure and reduces the cost of constructing and maintaining the wind turbine transmission system.

[0034] The cost of the AC transmission line 22 in the embodiment of the present application is lower than that of a DC transmission line. AC transmission technology is more mature and easier to implement than DC transmission technology, further reducing the cost of constructing and maintaining the wind turbine transmission system. Furthermore, in the case of DC transmission, the DC transmission line has no zero crossing, making disconnection difficult and requiring the installation of a DC circuit breaker. However, in the embodiment of the present application, the use of the AC transmission line 22 eliminates the need for a DC circuit breaker, further reducing the cost of constructing and maintaining the wind turbine transmission system.

[0035] The following describes the wind turbine power transmission system using two scenarios: single-phase transmission and three-phase transmission.

[0036] Figure 3 Schematic diagram of an example of a wind turbine generator system in an embodiment of the present application. Figure 3 The wind turbine power transmission system shown is a single-phase power transmission system for wind turbines. Figure 3 As shown, the AC transmission line 22 in the wind turbine generator set includes a first AC transmission line 221 and a second AC transmission line 222 .

[0037] The first end of the AC wind turbine matrix 21 is connected to the first AC transmission line 221. The second end of the AC wind turbine matrix 21 is connected to the second AC transmission line 222. Specifically, one end of the first AC transmission line 221 is connected to the first end of the AC wind turbine matrix 21, and the other end of the first AC transmission line 221 is connected to the converter station 23. One end of the second AC transmission line 222 is connected to the second end of the AC wind turbine matrix 21, and the other end of the second AC transmission line 222 is connected to the converter station 23.

[0038] In some examples, the AC wind turbine generator matrix 21 includes N1 groups of AC wind turbine generators 221, and each group of AC wind turbine generator matrix 21 includes M1 AC wind turbine generators 221. N1 and M1 are positive integers. The specific values ​​can be set according to the working scenario and working requirements and are not limited here.

[0039] When N1=1 and M1=1, that is, the AC wind turbine generator matrix 21 includes one AC wind turbine generator 221, the first end of the AC wind turbine generator matrix 21 includes the first bus port of the AC wind turbine generator 221, and the second end of the AC wind turbine generator matrix 21 includes the second bus port of the AC wind turbine generator 221.

[0040] In the case of N1>1, N1 groups of AC wind turbine generator sets 221 are connected in parallel. In the case of M1>1, M1 AC wind turbine generator sets 221 in each group are connected in series. Figure 3As shown, the first output port of the first AC wind turbine generator set 221 in each group of AC wind turbine generator sets 221 is connected to the first AC transmission line 221. That is, the first end of the AC wind turbine generator matrix 21 may include the first output port of the first AC wind turbine generator set 221 in each group of AC wind turbine generator sets 221, and the first output port of the first AC wind turbine generator set 221 in each group of AC wind turbine generator sets 221 is connected. In each group of AC wind turbine generator sets 221, the second output port of the preceding AC wind turbine generator set 221 is connected to the first output port of the succeeding AC wind turbine generator set 221. The second output port of the last AC wind turbine generator set 221 in each group of AC wind turbine generator sets 221 is connected to the second AC transmission line 222. That is, the second end of the AC wind turbine generator matrix 21 may include the second output port of the last AC wind turbine generator set 221 in each group of AC wind turbine generator sets 221, and the second output port of the last AC wind turbine generator set 221 in each group of AC wind turbine generator sets 221 is connected.

[0041] The bus voltage level of the wind turbine generator system is the voltage level U of the AC transmission line 22. AC The transmission voltage level U of a single AC wind turbine generator set 221 ac The relationship between them is: U ac ×M1≥U AC .

[0042] By connecting N1 groups of AC wind turbine generator sets 221 in parallel, the capacity level of the wind turbine generator set transmission system can be improved; by connecting M1 AC wind turbine generator sets 221 in each group in series, the voltage level of the wind turbine generator set transmission system can be improved, thereby meeting the requirements for the wind turbine generator set transmission system.

[0043] In some examples, the converter station 23 may include a modular multilevel converter (MMC). The modular multilevel converter may include a first bridge arm, a second bridge arm, and a third bridge arm. The upper bridge arm in each bridge arm includes an inductor L1 and a power unit 231, and the lower bridge arm in each bridge arm includes an inductor L2 and a power unit 231. When the upper bridge arm includes two or more power units 231, the two or more power units 231 are connected in series. When the lower bridge arm includes two or more power units 231, the two or more power units 231 are connected in series. A point between the upper bridge arm and the lower bridge arm in each bridge arm of the modular multilevel converter is connected to the converter transformer 24.

[0044] Figure 4The power unit 231 may include an insulated gate bipolar transistor (IGBT) device T1, an IGBT device T2, an IGBT device T3, an IGBT device T4 and a capacitor C1, which are specifically connected as follows: Figure 4 As shown, no further details are given here.

[0045] The AC wind turbine generator set 221 in the above embodiment may specifically be a semi-direct drive AC wind turbine generator set 221 . Figure 5 FIG. 1 is a schematic structural diagram of an example of an AC wind turbine generator set in an embodiment of the present application. Figure 5 As shown, the AC wind turbine generator set 221 may include blades 2111 , a gearbox 2112 , a generator 2113 , a single-winding transformer 2114 , a reduced matrix converter (RMC) 2115 , a first switch unit 2116 , a second switch unit 2117 and a bypass switch unit 2118 .

[0046] The blades 2111 can be connected to the gearbox 2112 through a transmission structure. The gearbox 2112 and the generator 2113 form the key components of the semi-direct drive transmission chain and are connected to the simplified matrix converter 2115 through the single-winding transformer 2114. The primary side of the single-winding transformer 2114 is connected to the low-voltage side of the wind turbine generator set. Through the voltage isolation function of the single-winding transformer 2114, the secondary side of the single-winding transformer 2114 is used as the high-voltage connection side. The specific components connected to the secondary side can be high-voltage components, thereby increasing the voltage level of the AC wind turbine generator set 221, increasing the output power of a single AC wind turbine generator set 221, and reducing the number of AC wind turbine generator sets 221 connected in series in the AC wind turbine generator set matrix 21.

[0047] The input port of the simplified matrix converter 2115 is connected to the secondary side of the single-winding transformer 2114. The output port of the simplified matrix converter 2115 can specifically be a single-phase AC power interface. The first switch unit 2116 is located between the first output port of the simplified matrix converter 2115 and the first output port of the AC wind turbine generator 221. Specifically, one end of the first switch unit 2116 is connected to the first output port of the simplified matrix converter 2115, and the other end of the first switch unit 2116 is connected to the first output port of the AC wind turbine generator 221. The second switch unit 2117 is located between the second output port of the simplified matrix converter 2115 and the second output port of the AC wind turbine generator 221. Specifically, one end of the second switch unit 2117 is connected to the second output port of the simplified matrix converter 2115, and the other end of the second switch unit 2117 is connected to the second output port of the AC wind turbine generator 221. The bypass switch unit 2118 is located between the first output port of the AC wind turbine generator set 221 and the second output port of the AC wind turbine generator set 221. Specifically, one end of the bypass switch unit 2118 is connected to the first output port of the AC wind turbine generator set 221 and the other end of the first switch unit 2116, and the other end of the bypass switch unit 2118 is connected to the second output port of the AC wind turbine generator set 221 and the other end of the second switch unit 2117.

[0048] The first switch unit 2116 and the second switch unit 2117 have the same on-off state, while the first switch unit 2116 and the bypass switch unit 2118 have opposite on-off states, i.e., the second switch unit 2117 and the bypass switch unit 2118 also have opposite on-off states. For example, when the first switch unit 2116 and the second switch unit 2117 are on, the bypass switch unit 2118 is correspondingly off. For another example, when the first switch unit 2116 and the second switch unit 2117 are off, the bypass switch unit 2118 is correspondingly on.

[0049] When AC wind turbine generator set 221 is operating normally, the first switch unit 2116 and the second switch unit 2117 in the AC wind turbine generator set 221 are turned on, and the bypass switch unit 2118 is turned off. If AC wind turbine generator set 221 fails, the first switch unit 2116 and the second switch unit 2117 in the AC wind turbine generator set 221 are turned off, and the bypass switch unit 2118 is turned on. Power flows through the bypass switch unit 2118, disconnecting the faulty AC wind turbine generator set 221 from the wind turbine generator set power transmission system. In this case, the first switch unit 2116 and the second switch unit 2117 are in a zero voltage and zero current state and can be safely disconnected. Grounding the first switch unit 2116 and the second switch unit 2117 also allows for safe maintenance and repair of the AC wind turbine generator set 221. When the fault of the AC wind turbine generator set 221 is resolved, the first switch unit 2116 and the second switch unit 2117 can be turned on under zero voltage and zero current conditions, while the bypass switch unit 2118 is turned off, and the AC wind turbine generator set 221 can be put into the wind turbine generator set power transmission system.

[0050] The first switch unit 2116 , the second switch unit 2117 , and the bypass unit may include at least one switch device, and the type and quantity of the switch device and the connection relationship of the switch devices within the unit are not limited.

[0051] Figure 6 FIG. 1 is a structural diagram of an example of a simplified matrix converter in an embodiment of the present application. Figure 6 As shown, the simplified matrix converter 2115 may include three-phase bridge arms, each of which may include an upper bridge arm and a lower bridge arm. Each upper bridge arm includes two IGBT devices T5 and T6 connected in series, and each lower bridge arm includes two IGBT devices T7 and T8 connected in series.

[0052] The emitter of IGBT device T5 in the upper bridge arm is connected to the emitter of IGBT device T6. The emitter of IGBT device T7 in the lower bridge arm is connected to the emitter of IGBT device T8. The collector of IGBT device T6 in the upper bridge arm of the same phase bridge arm is connected to the collector of IGBT device T7 in the lower bridge arm. The first phase input terminal of the simplified matrix converter 2115 is connected to the first phase output terminal of the single-winding transformer 2114. The first phase input terminal of the simplified matrix converter 2115 includes the collector of IGBT device T6 and the collector of IGBT device T7 in the first phase bridge arm. The second phase input terminal of the simplified matrix converter 2115 is connected to the second phase output terminal of the single-winding transformer 2114. The second phase input terminal of the simplified matrix converter 2115 includes the collector of IGBT device T6 and the collector of IGBT device T7 in the second phase bridge arm. The third phase input terminal of the simplified matrix converter 2115 is connected to the second phase output terminal of the single-winding transformer 2114. The third phase input terminal of the simplified matrix converter 2115 includes the collector of the IGBT device T6 and the collector of the IGBT device T7 in the third phase bridge arm.

[0053] The collectors of the IGBT devices T5 in each upper bridge arm are connected, and the collectors of the IGBT devices T8 in each lower bridge arm are connected. The first output end of the simplified matrix converter 2115 includes the collectors of the connected IGBT devices T5 in each upper bridge arm, and the second output end of the simplified matrix converter 2115 includes the collectors of the connected IGBT devices T8 in each lower bridge arm.

[0054] The input of the simplified matrix converter 2115 is three-phase electric energy, and the output is single-phase electric energy, thereby completing the conversion of three-phase AC power to single-phase AC power.

[0055] Figure 7 Schematic diagram of another example of a wind turbine generator system in an embodiment of the present application. Figure 7 The wind turbine power transmission system shown is a three-phase power transmission system for wind turbines. Figure 7 As shown, the AC transmission line 22 in the wind turbine generator system includes a first-phase AC transmission line 223 , a second-phase AC transmission line 224 and a third-phase AC transmission line 225 .

[0056] The AC wind turbine matrix 21 includes a first-phase port, a second-phase port, and a third-phase port. The first-phase port of the AC wind turbine matrix 21 is connected to the first-phase AC transmission line 223. The second-phase port of the AC wind turbine matrix 21 is connected to the second-phase AC transmission line 224. The third-phase port of the AC wind turbine matrix 21 is connected to the third-phase AC transmission line 225. Specifically, one end of the first-phase AC transmission line 223 is connected to the first-phase port of the AC wind turbine matrix 21, and the other end of the first-phase AC transmission line 223 is connected to the converter station 23. One end of the second-phase AC transmission line 224 is connected to the second-phase port of the AC wind turbine matrix 21, and the other end of the second-phase AC transmission line 224 is connected to the converter station 23. One end of the third-phase AC transmission line 225 is connected to the third-phase port of the AC wind turbine matrix 21, and the other end of the third-phase AC transmission line 225 is connected to the converter station 23.

[0057] In some examples, such as Figure 7 As shown, the AC wind turbine generator matrix 21 includes three groups of AC wind turbine generators 221. Each group of AC wind turbine generator matrix 21 includes M2 AC wind turbine generators 221, where M2 is a positive integer. The specific value of M2 can be set according to the working scenario and working requirements and is not limited here.

[0058] In each group of AC wind turbine generator sets 221, the first output port of the first AC wind turbine generator set 221 is connected to the corresponding single-phase AC transmission line 22. The second output port of the last AC wind turbine generator set 221 in each group of AC wind turbine generator sets 221 is connected.

[0059] When M2 = 1, the first and last AC wind turbine generator sets 221 in each group of AC wind turbine generator sets 221 are the same AC wind turbine generator set 221. Specifically, the first output ports of the AC wind turbine generator sets 221 in the first group of AC wind turbine generator sets 221 are connected to the first-phase AC transmission line 223; the first output ports of the AC wind turbine generator sets 221 in the second group of AC wind turbine generator sets 221 are connected to the second-phase AC transmission line 224; and the first output ports of the AC wind turbine generator sets 221 in the third group of AC wind turbine generator sets 221 are connected to the third-phase AC transmission line 225. The second output ports of the AC wind turbine generator sets 221 in the first group of AC wind turbine generator sets 221, the second output ports of the AC wind turbine generator sets 221 in the second group of AC wind turbine generator sets 221, and the second output ports of the AC wind turbine generator sets 221 in the third group of AC wind turbine generator sets 221 are connected.

[0060] In the case of M2>1, M2 AC wind turbine generator sets 221 in each group of AC wind turbine generator sets 221 are connected in series. Figure 7 As shown, the first output port of the first AC wind turbine generator set 221 in the first group of AC wind turbine generator sets 221 is connected to the first-phase AC transmission line 223, and the first output port of the last AC wind turbine generator set 221 in the first group of AC wind turbine generator sets 221 is connected to the second output port of the previous AC wind turbine generator set 221. The first output port of the first AC wind turbine generator set 221 in the second group of AC wind turbine generator sets 221 is connected to the second-phase AC transmission line 224, and the first output port of the last AC wind turbine generator set 221 in the second group of AC wind turbine generator sets 221 is connected to the second output port of the previous AC wind turbine generator set 221. The first output port of the first AC wind turbine generator set 221 in the third group of AC wind turbine generator sets 221 is connected to the third-phase AC transmission line 225, and the first output port of the last AC wind turbine generator set 221 in the third group of AC wind turbine generator sets 221 is connected to the second output port of the previous AC wind turbine generator set 221. The second output port of the last AC wind generator set 221 in the first group of AC wind generator sets 221, the second output port of the last AC wind generator set 221 in the second group of AC wind generator sets 221 and the second output port of the last AC wind generator set 221 in the third group of AC wind generator sets 221 are connected.

[0061] The bus voltage level of the wind turbine generator system is the voltage level U of the AC transmission line 22. AC The transmission voltage level U of a single AC wind turbine generator set 221 ac The relationship between them is: U ac ×M2≥U AC .

[0062] By connecting the M2 AC wind turbine generator sets 221 in each group in series, the voltage level of the wind turbine generator set power transmission system can be increased, thereby meeting the demand for the wind turbine generator set power transmission system.

[0063] The specific structure of the AC wind turbine generator set 221 can be found in Figure 5 and Figure 6 The specific structure shown and the related descriptions in the above embodiments are not repeated here.

[0064] In some examples, the converter station 23 may include a modular multilevel matrix converter (M3C). The modular multilevel matrix converter is a new type of H-bridge cascade matrix converter, which includes a structure with nine bridge arms connected between the three-phase input and the three-phase output. The circuit parameters of each bridge arm can be equal and symmetrical and independent of each other. The modular multilevel matrix converter can convert high-voltage, low-frequency current into high-voltage power frequency current. The frequency conversion of the modular multilevel matrix converter is more flexible, not limited to multiples of the power frequency, and generates very few harmonics. The modular multilevel matrix converter can also solve the defect that power electronic devices cannot adapt to high-voltage and high-power environments due to their own characteristics and development limitations. In the wind turbine power transmission system in the embodiment of the present application, due to the presence of the modular multi-level matrix converter, there is no need to set up a sending-end converter station and a receiving-end converter station at the same time, thereby removing the DC structure part in the AC-DC conversion and DC-AC conversion. The number of bridge arms (upper bridge arm and lower bridge arm each count as one bridge arm) in the converter station 23 can be reduced by 1 / 4, thereby improving the flexibility and scalability of the control. Moreover, in the low-frequency control scenario, the modular multi-level matrix converter does not require additional common-mode voltage and current. It only needs to adjust the internal exchange of power between its own bridge arms to solve the problem of unstable voltage and current fluctuations caused by low frequency. The modular multi-level matrix converter can be better applied to wind turbine power transmission systems that transmit low-frequency AC or fractional-frequency AC.

[0065] Figure 8 This is a schematic diagram of an example of a modular multi-level matrix converter provided in an embodiment of the present application. Figure 8 As shown, the modular multi-level matrix converter includes three bridge arm power units 31. Each bridge arm power unit 31 includes a three-phase bridge arm power sub-unit. Figure 7 and Figure 8 Point S1 marks the other end of the first-phase AC transmission line 223, point S2 marks the other end of the second-phase AC transmission line 224, and point S3 marks the other end of the third-phase AC transmission line 225; point A1 marks the first-phase input end of the converter transformer 24, point B1 marks the second-phase input end of the converter transformer 24, and point C1 marks the third-phase input end of the converter transformer 24.

[0066] In each bridge arm power unit 31, the first port of the first-phase bridge arm power subunit 311 is connected to the first-phase output port of the modular multilevel matrix converter via an inductor L; the first port of the second-phase bridge arm power subunit 312 is connected to the second-phase output port of the modular multilevel matrix converter via an inductor L; the first port of the third-phase bridge arm power subunit 313 is connected to the third-phase output port of the modular multilevel matrix converter via an inductor L; the second port of the first-phase bridge arm power subunit 311, the second port of the second-phase bridge arm power subunit 312, and the second port of the third-phase bridge arm power subunit 313 are connected and connected to the corresponding single-phase AC transmission line 22. The first-phase output port of the modular multilevel matrix converter is connected to the first-phase input terminal of the converter transformer, the second-phase output port of the modular multilevel matrix converter is connected to the second-phase input terminal of the converter transformer, and the third-phase output port of the modular multilevel matrix converter is connected to the third-phase input terminal of the converter transformer.

[0067] A single-phase bridge arm power subunit may include at least one power module 41. If a single-phase bridge arm power subunit includes two or more power modules 41, the two or more power modules 41 in the single-phase bridge arm power subunit are connected in series. A single bridge arm power unit 31 includes a first-phase bridge arm power subunit 311, a second-phase bridge arm power subunit 312, and a third-phase bridge arm power subunit 313 on the corresponding three bridge arms.

[0068] Specifically, in the first bridge arm power unit 31, the second port of the first-phase bridge arm power subunit 311, the second port of the second-phase bridge arm power subunit 312, and the second port of the third-phase bridge arm power subunit 313 are connected, and are connected to the first-phase AC transmission line 223. The first bridge arm power unit 31 includes the first-phase bridge arm power subunit 311 on the first bridge arm, the second-phase bridge arm power subunit 312 on the second bridge arm, and the third-phase bridge arm power subunit 313 on the third bridge arm.

[0069] In the second bridge arm power unit 31, the second port of the first-phase bridge arm power subunit 311, the second port of the second-phase bridge arm power subunit 312, and the second port of the third-phase bridge arm power subunit 313 are connected, and are connected to the second-phase AC power transmission line 224. The second bridge arm power unit 31 includes a first-phase bridge arm power subunit 311 on the fourth bridge arm, a second-phase bridge arm power subunit 312 on the fifth bridge arm, and a third-phase bridge arm power subunit 313 on the sixth bridge arm.

[0070] In the third bridge arm power unit 31, the second port of the first-phase bridge arm power subunit 311, the second port of the second-phase bridge arm power subunit 312, and the second port of the third-phase bridge arm power subunit 313 are connected, and are connected to the third-phase AC power transmission line 225. The third bridge arm power unit 31 includes the first-phase bridge arm power subunit 311 on the seventh bridge arm, the second-phase bridge arm power subunit 312 on the eighth bridge arm, and the third-phase bridge arm power subunit 313 on the ninth bridge arm.

[0071] Figure 9 The power module 41 may include an IGBT device T9, an IGBT device T10, an IGBT device T11, an IGBT device T12, a capacitor C2 and a switch device K1, which are specifically connected as follows: Figure 9 As shown, no further details are given here.

[0072] Figure 10 This is a structural diagram of another example of a wind turbine generator transmission system in an embodiment of the present application. Figure 10 The wind turbine power transmission system shown is a three-phase power transmission system for wind turbines. Figure 10 As shown, the AC transmission line 22 in the wind turbine generator system includes a first-phase AC transmission line 223 , a second-phase AC transmission line 224 and a third-phase AC transmission line 225 .

[0073] The AC wind turbine matrix 21 includes a first-phase port, a second-phase port, and a third-phase port. The first-phase port of the AC wind turbine matrix 21 is connected to the first-phase AC transmission line 223. The second-phase port of the AC wind turbine matrix 21 is connected to the second-phase AC transmission line 224. The third-phase port of the AC wind turbine matrix 21 is connected to the third-phase AC transmission line 225. Specifically, one end of the first-phase AC transmission line 223 is connected to the first-phase port of the AC wind turbine matrix 21, and the other end of the first-phase AC transmission line 223 is connected to the converter station 23. One end of the second-phase AC transmission line 224 is connected to the second-phase port of the AC wind turbine matrix 21, and the other end of the second-phase AC transmission line 224 is connected to the converter station 23. One end of the third-phase AC transmission line 225 is connected to the third-phase port of the AC wind turbine matrix 21, and the other end of the third-phase AC transmission line 225 is connected to the converter station 23.

[0074] In some examples, the AC wind turbine generator array matrix 21 includes M3 AC wind turbine generator arrays 221, where M3 is a positive integer. The specific value of M3 can be set according to the working scenario and working requirements and is not limited here. The bus voltage level of the wind turbine generator transmission system is the voltage level U of the AC transmission line 22. ACThe transmission voltage level U of a single AC wind turbine generator set 221 ac The relationship between them is: U ac ×M3≥U AC .

[0075] In some examples, the converter station 23 may include a modular multi-level matrix converter. For details on the modular multi-level matrix converter, see Figure 8 The relevant contents in the above embodiments will not be repeated here.

[0076] Figure 11 FIG. 1 is a structural diagram of another example of an AC wind turbine generator set in the embodiment of the present application. Figure 10 and Figure 11 As shown, each AC wind turbine generator set 221 includes a three-phase simplified matrix converter 2115. Each AC wind turbine generator set 221 also includes blades 2111, a gearbox 2112, a generator 2113 and a single-winding transformer 2114. The three-phase simplified matrix converters 2115 are respectively a first-phase simplified matrix converter 21151, a second-phase simplified matrix converter 21152 and a third-phase simplified matrix converter 21153. The specific structure of each phase simplified matrix converter 2115 can be found in Figure 6 The related descriptions in the above embodiments will not be repeated here.

[0077] The blades 2111 can be connected to the gearbox 2112 through a transmission structure. The gearbox 2112 and the generator 2113 form the key components of the semi-direct drive transmission chain and are connected to the three-phase simplified matrix converter 2115 through the single-winding transformer 2114. The primary side of the single-winding transformer 2114 is connected to the low-voltage side of the wind turbine generator set, and the secondary side of the single-winding transformer 2114 is used as the high-voltage connection side through the voltage isolation function of the single-winding transformer 2114. The specific components connected to the secondary side can be high-voltage components, thereby increasing the voltage level of the AC wind turbine generator set 221, increasing the output power of a single AC wind turbine generator set 221, and reducing the number of AC wind turbine generator sets 221 connected in series in the AC wind turbine generator set matrix 21.

[0078] In each AC wind turbine generator set 221, the single-winding transformer 2114 is respectively connected to the input port of the first-phase reduced matrix converter 21151, the input port of the second-phase reduced matrix converter 21152, and the input port of the third-phase reduced matrix converter 21153. In each AC wind turbine generator set 221, the input port of the first-phase reduced matrix converter 21151, the input port of the second-phase reduced matrix converter 21152, and the input port of the third-phase reduced matrix converter 21153 are connected.

[0079] When M3>1, the first-phase simplified matrix converters 21151 in each AC wind turbine generator set 221 are connected in series, the second-phase simplified matrix converters 21152 in each AC wind turbine generator set 221 are connected in series, and the third-phase simplified matrix converters 21153 in each AC wind turbine generator set 221 are connected in series. Specifically, when M3>1, the first-phase simplified matrix converter 21151 in the first AC wind turbine generator set 221 to the first-phase simplified matrix converter 21151 in the M3-th AC wind turbine generator set 221 are connected in series; specifically, the first output port of the first-phase simplified matrix converter 21151 in the subsequent AC wind turbine generator set 221 is connected to the second output port of the first-phase simplified matrix converter 21151 in the previous AC wind turbine generator set 221. The second-phase reduced matrix converter 21152 in the first AC wind turbine generator set 221 is connected in series to the second-phase reduced matrix converter 21152 in the M3-th AC wind turbine generator set 221. Specifically, the first output port of the second-phase reduced matrix converter 21152 in the latter AC wind turbine generator set 221 is connected to the second output port of the second-phase reduced matrix converter 21152 in the previous AC wind turbine generator set 221. The third-phase reduced matrix converter 21153 in the first AC wind turbine generator set 221 is connected in series to the third-phase reduced matrix converter 21153 in the M3-th AC wind turbine generator set 221. Specifically, the first output port of the third-phase reduced matrix converter 21153 in the latter AC wind turbine generator set 221 is connected to the second output port of the third-phase reduced matrix converter 21153 in the previous AC wind turbine generator set 221.

[0080] In the first AC wind turbine generator set 221, the first output port of the first-phase streamlined matrix converter 21151 is connected to the first-phase AC transmission line 223, the first output port of the second-phase streamlined matrix converter 21152 is connected to the second-phase AC transmission line 224, and the first output port of the third-phase streamlined matrix converter 21153 is connected to the third-phase AC transmission line 225.

[0081] In the last AC wind turbine generator set 221 , the second output port of the first-phase simplified matrix converter 21151 , the second output port of the second-phase simplified matrix converter 21152 , and the second output port of the third-phase simplified matrix converter 21153 are connected.

[0082] It should be noted that the various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences from other embodiments. This application is not limited to the specific steps and structures described above and shown in the figures. Those skilled in the art may make various changes, modifications, and additions after understanding the spirit of this application. In addition, for the sake of brevity, a detailed description of known technologies is omitted here.

[0083] Those skilled in the art should understand that the above embodiments are illustrative rather than restrictive. Different technical features appearing in different embodiments can be combined to achieve beneficial effects. Based on a study of the drawings, the specification and the claims, those skilled in the art should be able to understand and implement other variations of the disclosed embodiments. In the claims, the term "including" does not exclude other structures; the quantifier "one" does not exclude a plurality; the terms "first" and "second" are used to identify names rather than to indicate any specific order. Any figure marks in the claims should not be understood as limiting the scope of protection. The functions of multiple parts appearing in the claims can be implemented by a separate hardware or software module. The fact that certain technical features appear in different dependent claims does not mean that these technical features cannot be combined to achieve beneficial effects.

Claims

1. A wind turbine power transmission system, characterized in that: comprising an AC wind turbine generator array matrix, an AC transmission line, a converter station, a converter transformer and an AC power grid electrically connected in sequence, wherein the AC wind turbine generator array matrix is ​​connected to the AC transmission line; The AC power transmission line is used to transmit low-frequency AC power or divided-frequency AC power, wherein the low-frequency AC power and the divided-frequency AC power are AC power with a frequency lower than the industrial frequency; The AC wind turbine generator array matrix includes N groups of AC wind turbine generator arrays, each group of AC wind turbine generator arrays includes two or more AC wind turbine generator arrays, and the two or more AC wind turbine generator arrays in each group are connected in series, and N is a positive integer; The AC transmission line includes a first AC transmission line and a second AC transmission line, a first end of the AC wind turbine generator array matrix is ​​connected to the first AC transmission line, and a second end of the AC wind turbine generator array matrix is ​​connected to the second AC transmission line; or, The AC transmission line includes a first-phase AC transmission line, a second-phase AC transmission line and a third-phase AC transmission line. The first-phase port of the AC wind turbine generator matrix is ​​connected to the first-phase AC transmission line, the second-phase port of the AC wind turbine generator matrix is ​​connected to the second-phase AC transmission line, and the third-phase port of the AC wind turbine generator matrix is ​​connected to the third-phase AC transmission line.

2. The wind turbine power transmission system according to claim 1, characterized in that: In a case where the AC transmission line includes a first AC transmission line and a second AC transmission line, the converter station includes a modular multilevel converter.

3. The wind turbine generator system according to claim 1, wherein: The AC wind turbine generator set matrix includes N1 groups of AC wind turbine generator sets, each group of AC wind turbine generator set matrix includes M1 AC wind turbine generator sets, and N1 and M1 are positive integers; When N1>1, N1 groups of AC wind turbines are connected in parallel; When M1>1, M1 AC wind turbine generator sets in each group are connected in series.

4. The wind turbine power transmission system according to claim 1, characterized in that: In a case where the AC transmission line includes a first-phase AC transmission line, a second-phase AC transmission line, and a third-phase AC transmission line, the converter station includes a modular multi-level matrix converter.

5. The wind turbine generator system according to claim 1, wherein: The AC wind turbine generator set matrix includes three groups of AC wind turbine generator sets, and each group of AC wind turbine generator set matrix includes M2 AC wind turbine generator sets, where M2 is a positive integer; In each group of AC wind turbine generator sets, the first output port of the first AC wind turbine generator set is connected to the corresponding single-phase AC transmission line, and the second output port of the last AC wind turbine generator set in each group of AC wind turbine generator sets is connected; When M2>1, M2 AC wind turbine generator sets in each group of AC wind turbine generator sets are connected in series.

6. The wind turbine generator system according to claim 1, wherein: The AC wind turbine generator matrix includes M3 AC wind turbine generators, where M3 is a positive integer; Each AC wind turbine generator set includes a three-phase simplified matrix converter, and the input port of the first-phase simplified matrix converter, the input port of the second-phase simplified matrix converter, and the input port of the third-phase simplified matrix converter in each AC wind turbine generator set are connected; When M3>1, the first-phase simplified matrix converters in each AC wind turbine generator set are connected in series, the second-phase simplified matrix converters in each AC wind turbine generator set are connected in series, and the third-phase simplified matrix converters in each AC wind turbine generator set are connected in series. In the first AC wind turbine generator set, the first output port of the first-phase streamlined matrix converter is connected to the first-phase AC transmission line, the first output port of the second-phase streamlined matrix converter is connected to the second-phase AC transmission line, and the first output port of the third-phase streamlined matrix converter is connected to the third-phase AC transmission line; In the last AC wind turbine generator set, the second output port of the first-phase simplified matrix converter, the second output port of the second-phase simplified matrix converter, and the second output port of the third-phase simplified matrix converter are connected.

7. The wind turbine power transmission system according to claim 3 or 5, characterized in that: Each of the AC wind turbine generator sets includes blades, a gearbox, a generator, a single-winding transformer, a simplified matrix converter, a first switch unit, a second switch unit, and a bypass switch unit. The first switch unit is located between the first output port of the streamlined matrix converter and the first output port of the AC wind turbine generator set, the second switch unit is located between the second output port of the streamlined matrix converter and the second output port of the AC wind turbine generator set, and the bypass switch unit is located between the first output port of the AC wind turbine generator set and the second output port of the AC wind turbine generator set.

8. The wind turbine power transmission system according to claim 7, characterized in that: The on-off states of the first switch unit and the second switch unit are the same, and the on-off states of the first switch unit and the bypass switch unit are opposite.

9. The wind turbine power transmission system according to claim 6, characterized in that: Each of the AC wind turbine generator sets also includes blades, a gearbox, a generator and a single-winding transformer. In each of the AC wind turbine generator sets, the single-winding transformer is respectively connected to the input port of the first-phase simplified matrix converter, the input port of the second-phase simplified matrix converter, and the input port of the third-phase simplified matrix converter.

10. The wind turbine generator system according to claim 4, characterized in that: The modular multi-level matrix converter includes three bridge arm power units, each of which includes a three-phase bridge arm power subunit; In each of the bridge arm power units, the first port of the first-phase bridge arm power subunit is connected to the first-phase output port of the modular multi-level matrix converter through an inductor device, the first port of the second-phase bridge arm power subunit is connected to the second-phase output port of the modular multi-level matrix converter through an inductor device, the first port of the third-phase bridge arm power subunit is connected to the third-phase output port of the modular multi-level matrix converter through an inductor device, the second port of the first-phase bridge arm power subunit, the second port of the second-phase bridge arm power subunit, and the second port of the third-phase bridge arm power subunit are connected and connected to the corresponding single-phase AC transmission line.

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