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A power circuit, a converter structure and a wind power generation system thereof are disclosed. The power circuit includes a first converter having an AC input side and a DC output side, a second converter having a DC input side and an AC output side, and a DC bus storage unit electrically connecte

A power circuit, a converter structure and a wind power generation system thereof are disclosed. The power circuit includes a first converter having an AC input side and a DC output side, a second converter having a DC input side and an AC output side, and a DC bus storage unit electrically connected to the DC output side of the first converter and the DC input side of the second converter. A level number, a switching valve type and/or a circuit connection of the first converter are different from those of the second converter.

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1. A converter structure, comprising: a generator-side converter having a DC side and an AC side, wherein the AC side of the generator-side converter is connected to a power generator, and the generator-side converter includes at least one switch;a grid-side converter having a DC side and an AC side

1. A converter structure, comprising: a generator-side converter having a DC side and an AC side, wherein the AC side of the generator-side converter is connected to a power generator, and the generator-side converter includes at least one switch;a grid-side converter having a DC side and an AC side, wherein the AC side of the grid-side converter is connected to an AC electric grid, and the grid-side converter includes at least one switch and has a three-phase structure;a generator-side control circuit configured to control turning on and off of the at least one switch of the generator-side converter;a grid-side control circuit configured to control turning on and off of the at least one switch of the grid-side converter; anda DC bus storage unit electrically connected to the DC side of the generator-side converter and the DC side of the grid-side converter so as to store a DC voltage;wherein the generator-side converter has a two-level structure, the grid-side converter has a three-level structure, and a switching frequency of the generator-side converter is lower than a switching frequency of the grid-side converter. 2. The converter structure of claim 1, wherein a switch type of the generator-side converter is different from a switch type of the grid-side converter. 3. The converter structure of claim 1, wherein a circuit connection of the generator-side converter is different from a circuit connection of the grid-side converter. 4. The converter structure of claim 1, wherein the generator-side control circuit comprises: a power regulator outputting a current instruction signal according to parameters reflecting the current power of the power generator and a preset parameter; anda current regulator outputting a pulse-width modulation (PWM) control signal according to a three-phase current signal from the power generator and the current instruction signal,wherein the generator-side control circuit controls the turning on and off of the switch of the generator-side converter through the PWM control signal. 5. The converter structure of claim 4, wherein the generator-side control circuit further comprises: a power comparator arranged between the power generator and the power regulator, so as to receive the parameters reflecting the current power of the power generator and the preset parameter and output a difference value to the power regulator. 6. The converter structure of claim 4, wherein the generator-side control circuit further comprises: a current comparator arranged between the power regulator and the current regulator, so as to receive the current instruction signal and the three-phase current signal from the power generator, and output a current difference value to the current regulator. 7. The converter structure of claim 4, wherein the parameters reflecting the current power of the power generator comprise a power, a rotating speed and a torque of the power generator. 8. The converter structure of claim 1, wherein the grid-side control circuit comprises: a voltage regulator outputting a current instruction signal according to the DC voltage and a reference voltage; anda current regulator outputting a pulse-width modulation (PWM) control signal according to a three-phase current signal from the AC electric grid and the current instruction signal,wherein the grid-side control circuit controls the turning on and off of the switch of the grid-side converter through the PWM control signal. 9. The converter structure of claim 8, wherein the grid-side control circuit further comprises: a voltage comparator receiving the DC voltage and the reference voltage, and outputting a voltage difference value to the voltage regulator. 10. The converter structure of claim 8, wherein the grid-side control circuit further comprises: a current comparator arranged between the voltage regulator and the current regulator, so as to receive the current instruction signal and the three-phase current signal from the AC electric grid, and output a current difference value to the current regulator. 11. The converter structure of claim 1, further comprising a filter arranged between the AC side of the grid-side converter and the AC electric grid. 12. A power circuit capable of two-way energy transmission and applicable to a wind power generation system, comprising: a first converter having an AC input side and a DC output side, so as to convert an AC power into a DC power;a second converter having a DC input side and an AC output side, so as to convert the DC power into another AC power, wherein each of the first converter and the second converter includes at least one switch;a first control circuit configured to control turning on and off of the at least one switch of the first converter;a second control circuit configured to control turning on and off of the at least one switch of the second converter; anda DC bus storage unit electrically connected to the DC output side of the first converter and the DC input side of the second converter,wherein a level number, a switch type and/or a circuit connection of the first converter are different from a level number, a switch type and/or a circuit connection of the second converter, wherein the second converter has a three-phase structure,wherein a switching frequency of the first converter is lower than a switching frequency of the second converter. 13. The power circuit of claim 12, wherein one of the first converter and the second converter has a two-level structure, and the other has a three-level structure. 14. The power circuit of claim 12, wherein when the circuit connection of the first converter is different from the circuit connection of the second converter, the first converter and the second converter both have a three-level structure. 15. The power circuit of claim 12, wherein the power grade of the wind power generation system is between 10 kW and 100 kW. 16. The power circuit of claim 12, wherein when energy is transmitted from the wind power generator to the AC electric grid in the wind power generation system, the first converter is electrically connected to the wind power generator, and the second converter is electrically connected to the AC electric grid. 17. The power circuit of claim 12, wherein when energy is transmitted from the AC electric grid to the wind power generator in the wind power generation system, the first converter is electrically connected to the AC electric grid, and the second converter is electrically connected to the wind power generator. 18. A wind power generation system, comprising a wind power generator and a converter module, wherein the converter module comprises at least one converter structure of claim 1. 19. The wind power generation system of claim 18, wherein the power grade of the wind power generation system is between 10 kW and 100 kW. 20. The wind power generation system of claim 18, wherein the converter module comprises a first converter structure and a second converter structure, the AC side of the generator-side converter of the first converter structure is connected in parallel with the AC side of the generator-side converter of the second converter structure, and the AC side of the grid-side converter of the first converter structure is connected in parallel with the AC side of the grid-side converter of the second converter structure. 21. The wind power generation system of claim 20, wherein the grid-side converter of the first converter structure is connected to an AC electric grid through a first filter, and the grid-side converter of the second converter structure is connected to the AC electric grid through a second filter.