Transformer-free high-voltage direct-hanging wind generating set

Abstract

The invention discloses a transformer-free high-voltage direct-hanging wind generating set. The transformer-free high-voltage direct-hanging wind generating set comprises a wind wheel, a transmission chain, a generator and a cascaded H-bridge wind power converter, the wind wheel is connected to the generator through a transmission chain and drives the generator to rotate; the generator realizes energy conversion from mechanical energy to electric energy, and the generated electric energy is fed into a power grid through the cascaded H-bridge wind power converter; the output end of the cascaded H-bridge wind power converter is directly connected to a high-voltage power distribution network in a wind power plant, so that the wind generating set does not need to be equipped with a special boosting transformer. By means of the cascade topology scheme of the wind generating set, the capacity and the voltage level of the wind power converter are improved, and meanwhile the economical efficiency and the reliability of the wind generating set are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wind power generation, and in particular relates to a transformer-free high-voltage direct-mounted wind power generator set. Background Art

[0002] As the most important renewable energy source, wind energy has developed rapidly in recent years. The wind power industry has been vigorously developed and the installed capacity has been continuously increased.

[0003] Wind turbines are constantly developing in the direction of large-scale development. At present, the offshore 18MW semi-direct-drive wind turbine developed by Dongfang Wind Power has been connected to the grid for power generation. With the continuous increase in power, on the one hand, it is necessary to increase the capacity of wind power converters, and on the other hand, in order to reduce the loss and cable twisting problems caused by large currents, the voltage level of wind power converters needs to be further improved urgently.

[0004] Wind turbines require a large initial investment. In order to improve the economy of wind power and increase the return on investment, it is urgent to develop economical and reliable wind turbines. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of the prior art and disclose a transformerless high-voltage direct-mounted wind turbine generator set. The cascade topology scheme of the wind turbine generator set proposed by the present invention increases the capacity and voltage level of the wind power converter, while improving the economy and reliability of the wind turbine generator set.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A transformerless high-voltage direct-mounted wind turbine generator set, the transformerless high-voltage direct-mounted wind turbine generator set comprising: a wind wheel, a transmission chain, a generator and a cascaded H-bridge wind power converter;

[0008] The wind wheel is connected to the generator through a transmission chain and drives the generator to rotate;

[0009] The generator realizes the energy conversion from mechanical energy to electrical energy, and the generated electrical energy is fed into the grid through the cascaded H-bridge wind power converter;

[0010] The output end of the cascaded H-bridge wind power converter is directly connected to the high-voltage distribution network in the wind farm, so that the wind turbine generator set does not need to be equipped with a dedicated step-up transformer.

[0011] According to a preferred embodiment, the generator is provided with a plurality of windings, each winding being connected in a star connection or a delta connection.

[0012] According to a preferred embodiment, the windings in the generator are insulated from each other.

[0013] According to a preferred embodiment, the number of windings in the generator is equal to the number of H-bridge modules in the cascaded H-bridge wind power converter;

[0014] The number of windings in the generator is determined by the generator voltage level, the grid-connected voltage of the wind turbine generator set and the output voltage of a single H-bridge power module in the cascaded H-bridge wind power converter.

[0015] According to a preferred embodiment, the cascaded H-bridge wind power converter is a three-phase converter, and each phase is obtained by connecting several H-bridge module output ends in series;

[0016] After the H-bridge modules in the three phases are connected in series, the first end is connected to form a neutral point, and the end is connected in series with a filter and then connected to the high-voltage distribution network in the wind farm.

[0017] According to a preferred embodiment, each H-bridge module in the cascaded H-bridge wind power converter has a three-wire input connected to a winding of a generator, and each H-bridge module has a two-wire AC output.

[0018] According to a preferred embodiment, the cascaded H-bridge wind power converter adopts an AC-DC-AC two-stage conversion topology structure, the front stage rectifies the three-phase power input by the generator, and the rear stage adopts an H-bridge inverter output.

[0019] The aforementioned main scheme of the present invention and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection by the present invention. After understanding the scheme of the present invention, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present invention, and they are not exhaustively listed here.

[0020] Beneficial effects of the present invention:

[0021] (1) A single wind turbine is directly connected to the high-voltage distribution network of the wind farm, eliminating the transformer on the wind turbine side and the transformer loss, which is conducive to improving the economy of the system;

[0022] (2) By adopting the cascade topology solution, the voltage on the grid side of the converter can be easily increased, the current can be reduced, thinner cables can be selected, the economy can be improved, and the twisted cable problem can be solved;

[0023] (3) The cascade topology can easily achieve high-power conversion and meet the large-capacity conversion requirements brought about by the large-scale unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the wind turbine generator system of the present invention.

[0025] Figure 2 It is a schematic diagram of the electric energy conversion system of the wind turbine generator set of the present invention.

[0026] Figure 3 This is the H-bridge module topology structure adopted in Example 1 of the present invention.

[0027] Figure 4 It is a schematic diagram of the electric energy conversion system according to embodiment 1 of the present invention.

[0028] Figure 5 This is the H-bridge module topology structure adopted in Example 2 of the present invention.

[0029] Figure 6 It is a schematic diagram of the electric energy conversion system of embodiment 2 of the present invention. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, and it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In addition, the present invention should be pointed out that, in the present invention, unless the specific structure, connection relationship, positional relationship, power source relationship, etc. are specifically written out, the structure, connection relationship, positional relationship, power source relationship, etc. involved in the present invention are all known by those skilled in the art on the basis of the prior art without creative work.

[0033] The invention discloses a transformer-free high-voltage direct-mounted wind power generator set, which comprises a wind wheel, a transmission chain, a generator and a cascaded H-bridge wind power converter.

[0034] As attached Figure 1 As shown, the wind wheel rotates freely under the action of wind, and drives the generator to rotate through the transmission chain, realizing the conversion of mechanical energy into electrical energy. The electrical energy generated by the generator is directly fed into the high-voltage grid through the cascaded H-bridge wind power converter.

[0035] As attached Figure 2 As shown, the generator adopts a multi-winding structure, each winding is insulated from each other, and each winding is respectively connected to each H-bridge module of the wind power converter.

[0036] The number of generator windings is equal to the number of H-bridge modules of the cascaded H-bridge wind power converter, which is determined by the generator voltage level, the wind turbine grid-connected voltage and the output voltage of a single H-bridge power module of the wind power converter.

[0037] The cascaded H-bridge wind power converter is a three-phase converter, each phase of which is obtained by connecting the output ends of multiple H-bridge modules in series.

[0038] After the three-phase H-bridge modules are connected in series, the first end is directly connected to form a neutral point, and the end is connected in series with a filter and directly connected to the high-voltage distribution network in the wind farm.

[0039] Each H-bridge module in the cascaded H-bridge wind power converter has a three-wire input connected to a winding of the generator, and each H-bridge module has a two-wire AC output.

[0040] By adopting the cascade topology solution, the converter in the wind turbine can easily increase the voltage on the grid side of the converter, reduce the current, and select thinner cables to improve economy and solve the cable twisting problem. In addition, the cascade topology can easily achieve high-power conversion and meet the large-capacity conversion requirements brought about by the large-scale unit.

[0041] Example 1

[0042] The wind turbine is directly connected to the 35kV system. The generator is designed with 54 independent windings, and each cascaded H-bridge converter uses 18 H-bridge modules in series.

[0043] As attached Figure 3 As shown, the H-bridge module topology structure in Example 1 is shown, the front stage adopts the NPC three-phase three-level topology structure, and the rear stage adopts the NPC three-level H-bridge structure.

[0044] As attached Figure 4 As shown, a schematic diagram of the electric energy conversion system of Example 1 is shown. The total number of generator windings is 54, which are divided into three groups and respectively connected to the three-phase H-bridge module of the wind power converter. The 18 H-bridge outputs of each phase are connected in series. After the series connection, one end forms a neutral point, and the other end is connected to the 35kV power grid through an inductor.

[0045] Example 2

[0046] The wind turbine is directly connected to the 10kV system. The generator is designed with 27 independent windings, and each cascaded H-bridge converter uses 9 H-bridge modules in series.

[0047] As attached Figure 5As shown, the H-bridge module topology structure in Example 2 is shown, the front stage adopts a three-phase two-level topology structure, and the back stage adopts a two-level H-bridge structure.

[0048] As attached Figure 6 As shown, a schematic diagram of the electric energy conversion system of Example 2 is shown. The total number of generator windings is 27, which are divided into three groups and respectively connected to the three-phase H-bridge module of the wind power converter. The 9 H-bridge outputs of each phase are connected in series. After the series connection, one end forms a neutral point, and the other end is connected to the 10kV power grid through an inductor.

[0049] It can be seen from the above embodiments that in the technical solution of the present invention, a single wind turbine is directly connected to the high-voltage distribution network, which saves the transformer on the wind turbine side and eliminates transformer loss, which is beneficial to improving the economy of the system; by adopting a cascade topology solution, it is easy to increase the voltage on the grid side of the converter, reduce the current, and select thinner cables to improve the economy and solve the cable twisting problem; after adopting the cascade topology, high-power conversion can be easily achieved, meeting the large-capacity conversion requirements brought about by the large-scale unit.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A transformerless high-voltage direct-mounted wind turbine generator set, characterized in that: The transformerless high-voltage direct-mounted wind turbine generator set comprises: a wind wheel, a transmission chain, a generator and a cascaded H-bridge wind power converter; The wind wheel is connected to the generator through a transmission chain and drives the generator to rotate; The generator realizes the energy conversion from mechanical energy to electrical energy, and the generated electrical energy is fed into the grid through the cascaded H-bridge wind power converter; The output end of the cascaded H-bridge wind power converter is directly connected to the high-voltage distribution network in the wind farm, so that the wind turbine generator set does not need to be equipped with a dedicated step-up transformer.

2. The transformerless high-voltage direct-mounted wind turbine generator set according to claim 1, characterized in that: The generator is provided with a plurality of windings, each winding being connected in a star connection or a triangle connection.

3. The transformerless high-voltage direct-mounted wind turbine generator set according to claim 2, characterized in that: The windings in the generator are insulated from each other.

4. The transformerless high-voltage direct-mounted wind turbine generator set according to claim 2, characterized in that: The number of windings in the generator is equal to the number of H-bridge modules in the cascaded H-bridge wind power converter; The number of windings in the generator is determined by the generator voltage level, the grid-connected voltage of the wind turbine generator set and the output voltage of a single H-bridge power module in the cascaded H-bridge wind power converter.

5. The transformerless high-voltage direct-mounted wind turbine generator set according to claim 4, characterized in that: The cascaded H-bridge wind power converter is a three-phase converter, each phase of which is obtained by connecting several H-bridge module output ends in series; After the H-bridge modules in the three phases are connected in series, the first end is connected to form a neutral point, and the end is connected in series with a filter and then connected to the high-voltage distribution network in the wind farm.

6. The transformerless high-voltage direct-mounted wind turbine generator set according to claim 5, characterized in that: Each H-bridge module in the cascaded H-bridge wind power converter has a three-wire input connected to a winding of a generator, and each H-bridge module has a two-wire AC output.

7. The transformerless high-voltage direct-mounted wind turbine generator set according to claim 1, characterized in that: The cascaded H-bridge wind power converter adopts an AC-DC-AC two-stage conversion topology structure, the front stage rectifies the three-phase power input by the generator, and the rear stage adopts an H-bridge inverter output.

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