CN219436654U - Variable-frequency electricity taking device of wind power generation system and wind power generation system - Google Patents

Abstract

The utility model provides a wind power generation system's frequency conversion electricity-taking device and wind power generation system, frequency conversion electricity-taking device includes rectifier circuit, chopper boost circuit and inverter circuit, rectifier circuit's output side is connected to chopper boost circuit's input side, chopper boost circuit's output side is connected to inverter circuit's input side, wherein, rectifier circuit's input side phase number is the n times of exchanging the busbar phase number, n is the integer that is greater than or equal to 2, chopper boost circuit's bridge arm's quantity is 3 integer times. According to the variable-frequency power taking device of the wind power generation system and the wind power generation system, the problem that power cannot be supplied to an electric component of the wind power generation system through the wind power generator set is solved, the structure of the whole wind power generation system can be simplified, the cost is saved, and the electric energy quality is improved.

Description

Variable-frequency electricity taking device of wind power generation system and wind power generation system

Technical Field

The application relates to the technical field of wind power generation, in particular to a variable-frequency electricity taking device of a wind power generation system and the wind power generation system.

Background

In the existing wind power generation system, a wind power generator set in the wind power generation system can convert wind energy into electric energy and output the electric energy, and the electric energy output by the wind power generator set can be output to a power grid on one hand and can be used for supplying power to other electric components in the wind power generation system on the other hand. However, with the development of wind power technology, the types of wind power generation sets are increasingly diversified, so that the output electric frequency of the wind power generation set may be lower than the electric frequency of the electric components, in which case other electric components inside the wind power generation system cannot be supplied with power by the wind power generation set, so that additional power supply sources may be required, which is disadvantageous in simplifying the structure of the entire system, and may increase economic costs.

Taking an offshore wind power generation scenario as an example, fig. 1 shows a high-voltage ac delivery scheme, fig. 2 shows a high-voltage flexible dc delivery scheme, and fig. 3 shows a flexible low-frequency delivery scheme. In the schemes of fig. 1 and 2, the output electricity of the wind generating set is the same as the electricity demand in the wind generating system, so that other electrical components in the wind generating system can be powered by the wind generating set. However, since the wind turbine generator set is a low frequency set in the flexible low frequency delivery scheme of fig. 3, the frequency of the output power thereof is smaller than the power consumption requirement inside the wind turbine generator set, and thus the internal power consumption system cannot use the output power of the wind turbine generator set.

Disclosure of Invention

In view of the problem that in the existing wind power generation system, when the output electric frequency of a wind power generator set is lower than the electric frequency of an electric component, the electric component of the wind power generation system cannot be powered through the wind power generator set, the application provides a variable-frequency electricity taking device of the wind power generation system and the wind power generation system.

The first aspect of the application provides a variable frequency electricity taking device of a wind power generation system, the input side of the variable frequency electricity taking device is connected to an alternating current bus of a wind power generation unit in the wind power generation system, the output side of the variable frequency electricity taking device is connected to an electric component of the wind power generation system, wherein the variable frequency electricity taking device comprises a rectifying circuit, a chopper boost circuit and an inverter circuit, the output side of the rectifying circuit is connected to the input side of the chopper boost circuit, the output side of the chopper boost circuit is connected to the input side of the inverter circuit, the number of phases of the input side of the rectifying circuit is n times of the number of phases of the alternating current bus, n is an integer greater than or equal to 2, the number of bridge arms of the chopper boost circuit is an integer multiple of 3, and the output frequency of the inverter circuit is higher than the frequency of the alternating current bus.

Optionally, the number of bridge arms of the inverter circuit is greater than or equal to 2.

Optionally, the variable-frequency power taking device further comprises a phase-shifting transformer, wherein the input side of the phase-shifting transformer is used as the input side of the variable-frequency power taking device, and the number of phases of the output side of the phase-shifting transformer is equal to the number of phases of the input side of the rectifying circuit.

Optionally, the phase-shifting transformer is an isolation transformer.

Optionally, the variable-frequency power taking device further comprises a precharge protection circuit, wherein an input side of the precharge protection circuit is connected to an output side of the phase-shifting transformer, and an output side of the precharge protection circuit is connected to an input side of the rectifying circuit.

Optionally, the rectifying circuit is an uncontrolled rectifying circuit.

Optionally, the variable-frequency power taking device further comprises a machine side transformer, wherein the output side of the machine side transformer is used as the output side of the variable-frequency power taking device, and the machine side transformer is an isolation transformer.

Optionally, the variable-frequency power taking device further comprises a filter circuit, the inverter circuit is connected to the filter circuit, and the output side of the filter circuit is connected to the input side of the machine side transformer, wherein the filter circuit is an LC filter circuit.

A second aspect of the present application provides a wind power generation system comprising a variable frequency electricity extraction device according to an exemplary embodiment of the present application.

Optionally, the wind power generation system comprises a low-frequency wind power generator set, and the frequency of an alternating current bus of the low-frequency wind power generator set is less than 50 hertz.

According to the variable-frequency power taking device of the wind power generation system and the wind power generation system, the variable-frequency power taking device comprising the rectifying circuit, the chopping boost circuit and the inverter circuit can be arranged, so that even if the output electric frequency of the wind power generation set is lower than the electric frequency of an electric component, the power can be supplied to other electric components inside the wind power generation system through the wind power generation set, the structure of the whole wind power generation system can be simplified, the cost can be saved, and the power supply can be realized, meanwhile, the harmonic wave can be reduced, and the power quality of the power supply can be improved by reasonably configuring the input side phase number of the rectifying circuit, the bridge arm of the chopping boost circuit and the structure of the inverter circuit.

Drawings

Fig. 1 is a schematic diagram showing an example of a wind power generation and transmission scheme according to an exemplary embodiment of the present application.

Fig. 2 is a schematic diagram showing another example of a wind power generation and transmission scheme according to an exemplary embodiment of the present application.

Fig. 3 is a schematic diagram showing still another example of a wind power transmission scheme according to an exemplary embodiment of the present application.

Fig. 4 is a schematic diagram showing a variable frequency electricity extraction device of a wind power generation system and a wind power generation set according to an exemplary embodiment of the present application.

Fig. 5 is a schematic block diagram illustrating a variable frequency power extraction device of a wind power generation system according to an exemplary embodiment of the present application.

Fig. 6 is a schematic view showing the structure of a variable frequency electricity taking device of a wind power generation system according to an exemplary embodiment of the present application.

Reference numerals:

11. 21, 31: wind turbine generator systems 12, 22, 32: current collecting submarine cable, 13: offshore booster station, 14, 24, 34: high pressure outgoing submarine cable 15, 26, 36: on-shore grid-tie systems, 16, 27, 37: large grid system, 23: offshore boost converter platform, 25, 35: on-shore converter station, 33: offshore boosting platform, 41: blade, 42: generator, 43: rectifying unit, 44: inversion unit, 45: boost power transformation unit, 100: variable frequency electricity taking device, 110: rectifying circuit, 120: chopper boost circuit, 130: inverter circuit, 131: upper bridge arm, 132: lower leg, 140: phase-shifting transformer, 150: precharge protection circuit, 160: side transformer, 170: a filter circuit.

Detailed Description

The following detailed description is provided to assist the reader in obtaining a thorough understanding of the methods, apparatus, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent after an understanding of the disclosure of the present application. For example, the order of operations described herein is merely an example and is not limited to those set forth herein, but may be altered as will be apparent after an understanding of the disclosure of the present application, except for operations that must occur in a particular order. Furthermore, descriptions of features known in the art may be omitted for clarity and conciseness.

The features described herein may be embodied in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein have been provided to illustrate only some of the many possible ways to implement the methods, devices, and/or systems described herein, which will be apparent after an understanding of the present disclosure.

As used herein, the term "and/or" includes any one of the listed items associated as well as any combination of any two or more.

Although terms such as "first," "second," and "third" may be used herein to describe various elements, components, regions, layers or sections, these elements, components, regions, layers or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first member, first component, first region, first layer, or first portion referred to in the examples described herein may also be referred to as a second member, second component, second region, second layer, or second portion without departing from the teachings of the examples.

In the description, when an element (such as a layer, region or substrate) is referred to as being "on" another element, "connected to" or "coupled to" the other element, it can be directly "on" the other element, be directly "connected to" or be "coupled to" the other element, or one or more other elements intervening elements may be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" or "directly coupled to" another element, there may be no other element intervening elements present.

The terminology used herein is for the purpose of describing various examples only and is not intended to be limiting of the disclosure. Singular forms also are intended to include plural forms unless the context clearly indicates otherwise. The terms "comprises," "comprising," and "having" specify the presence of stated features, amounts, operations, components, elements, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, amounts, operations, components, elements, and/or combinations thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs after understanding this application. Unless explicitly so defined herein, terms (such as those defined in a general dictionary) should be construed to have meanings consistent with their meanings in the context of the relevant art and in the present application, and should not be interpreted idealized or overly formal.

In addition, in the description of the examples, when it is considered that detailed descriptions of well-known related structures or functions will cause a ambiguous explanation of the present application, such detailed descriptions will be omitted.

As described above, with the development of wind power technology, wind power generation sets are increasingly diversified in types, so that the output electrical frequency of the wind power generation set may be lower than the electrical frequency of the electrical components, and thus other electrical components inside the wind power generation system may not be powered by the wind power generation set.

For wind energy development and utilization approaches of wind power generation, most of wind energy development and utilization scenes are land wind farms, but with continuous progress of wind power technology, offshore wind power is rapidly developed in recent years. An offshore wind power generation scenario will be described below as an example.

Fig. 1 shows a schematic diagram of an example topology of a high voltage ac delivery scheme (hereinafter abbreviated as HVAC scheme) in offshore wind power generation. Specifically, the output electricity of the wind power generation set 11 in the wind farm is output through ac collection, and for example, the voltage of the output electricity may be 35 kilovolts (kV) and the frequency thereof may be 50 hertz (Hz). The output electricity of the wind farm can be transmitted to the offshore booster station 13 via the collecting sea cable 12, the offshore booster station 13 boosts the received electric energy, the voltage of the output electricity of the offshore booster station 13 increases, and the frequency is unchanged, for example, in the above example, the output electricity frequency of the offshore booster station 13 is still 50Hz. The boosted power may be delivered at a voltage of, for example, 110kV or 220kV or higher, which may be delivered from sea to land via the high voltage delivery sea cable 14, and then to the large grid system 16 via the onshore grid system 15.

For the HVAC scheme shown in fig. 1, the overall cost is low, the technology is mature, engineering experience is rich, and most of the offshore wind farms which are put into operation currently adopt the scheme. However, when offshore wind farm distances exceed a certain distance (e.g. about 60 km) due to the charging current of the sea cable system, HVAC solutions are no longer the most economical solution due to the need to add offshore reactive power compensation stations.

Fig. 2 shows a schematic diagram of an example topology of a high voltage flexible direct current output scheme (hereinafter abbreviated as VSC-HVDC scheme) in offshore wind power generation. Specifically, the output electricity of the wind power generation set 21 in the wind farm is output through ac collection, and for example, the voltage of the output electricity may be 35kV and the frequency thereof may be 50Hz. The output electricity of the wind power plant can be transmitted to the offshore boosting and converting platform 23 through the current collecting sea cable 22, the offshore boosting and converting platform 23 rectifies the received electric energy, the direct current rectified by the offshore boosting and converting platform 23 is transmitted to the onshore converter station 25 through the high-voltage output sea cable 24, then converted into 50Hz alternating current through the onshore converter station 25, and then transmitted to the large power grid system 27 through the onshore grid-connected system 26.

Compared with the HVAC scheme of fig. 1, the cost index of the VSC-HVDC transmission scheme shown in fig. 2 is better in deep-sea scenarios, for example, when the offshore distance of the offshore wind farm is within a certain range (about 60 km-180 km), but due to the comprehensive cost of the offshore conversion platform, the total engineering cost is still high, and the requirements of offshore wind power 'low price' development cannot be met due to the direct current breaker cost, the later operation and maintenance comprehensive cost and other reasons. In addition, in the scheme, a current collecting system in the wind farm is still identical to a conventional HVAC scheme, only the problem of a power transmission link is solved, and the related problem of a current collecting part cannot be solved.

When the 'low price' normalization of offshore wind power is imminent, the cost is reduced from the design cost of the single-machine cost reduction steering system based on the engineering reality that the 'single-machine cost reduction space of the wind turbine generator has reached the capacity boundary'. Against this background, a third technical route for offshore wind power has emerged, namely: a flexible low frequency transmission scheme (hereinafter abbreviated as LF (Low Frequency) -HVDC scheme).

Fig. 3 shows a schematic diagram of an example topology of an LF-HVDC scheme in offshore wind power generation. Specifically, the output power of the wind turbine generator system 31 in the wind farm is collected and output by low-frequency ac. The output electricity of the wind farm can be delivered to an offshore boosting platform 33 via a collector sea cable 32, the offshore boosting platform 33 boosting the received low frequency ac power and delivering it at high voltage and low frequency, which can be delivered from sea to land via a high voltage delivery sea cable 34 and then to a large grid system 37 via an onshore converter station 35 and an onshore grid system 36.

Compared with the VSC-HVAC scheme of fig. 2, the LF-HVDC transmission scheme of fig. 3 greatly reduces costs by eliminating the offshore converter platform; meanwhile, the method is not limited by the technical maturity and cost of the direct current breaker, has obvious economic advantages in offshore wind power delivery cases with the offshore distance of 60 km-180 km, and meets the development requirement of offshore wind power 'low price'.

As can be seen from fig. 1 to 3, as technology progresses, wind power generation schemes are continuously innovated, and the performance and economy are overall in a direction toward balance. However, innovations in wind power generation schemes can correspondingly introduce other problems.

For example, in the examples of fig. 1 and 2, the output electricity of the wind generating set is 50Hz, and the electricity demand inside the wind generating system is also 50Hz, so that other electrical components inside the wind generating system can be powered by the wind generating set.

However, since in the example of fig. 3 the wind power plant is a low frequency plant with an output power frequency of less than 50Hz, e.g. 690V/20Hz, and the power demand inside the wind power plant may be 380V/50Hz, the internal power system cannot be powered if the power from the ac bus of the wind power plant is not converted from 20Hz to 50Hz and from 690V to 380V.

Therefore, on one hand, in order to realize the engineering landing of the system scheme, the technical obstacle of the power supply side is required to develop a low-frequency wind generating set; on the other hand, with the application of the low-frequency wind generating set, a power supply device required for the internal load power utilization of the low-frequency wind generating set is also required to be developed.

In addition, considering the requirements of economy, operation reliability and power grid access friendliness of the wind turbine system, on one hand, when the wind turbine system is used for supplying power to the electric components in the wind turbine system through the wind turbine system, on the other hand, under the condition that high/low voltage faults occur on the power grid side, the wind turbine system needs to reliably and stably operate the power supply of the electric components in the wind turbine system, for example, all network-related technical indexes of the wind turbine system should meet the technical requirements of GB/T19963-2021; on the other hand, the power quality index of the power supplied to the internal electrical components needs to meet the power requirement of the internal load of the wind turbine, for example, the power quality technical index of harmonic distortion rate and the like affecting the normal operation of the internal load and the control system.

In view of the above, exemplary embodiments according to the present application provide a variable frequency power extraction device of a wind power generation system and a wind power generation system to solve at least one of the above problems.

According to a first aspect of the present application, a variable frequency power extraction device for a wind power generation system is provided, which may be used for example in a wind power generation system comprising a low frequency wind power generator set such as described in fig. 3. Here, it should be noted that, although the power transmission scheme of the offshore wind power generation is described above by taking fig. 1 to 3 as an example, it is merely an example, and the variable frequency power extraction device according to the embodiment of the present application is not limited to application to an offshore scenario, but may also be applied to a land scenario, and the like.

Fig. 4 shows a schematic diagram of a variable frequency power extraction device of a wind power generation system and a wind power generator set according to an exemplary embodiment of the present application, and fig. 5 shows a schematic block diagram of a variable frequency power extraction device of a wind power generation system according to an exemplary embodiment of the present application.

As shown in fig. 4, the wind power generation system may include a variable frequency power taking device 100 and a wind power generator set, an input side of the variable frequency power taking device 100 may be connected to an ac bus of the wind power generator set, and an output side of the variable frequency power taking device 100 may be connected to an electrical component of the wind power generation system, that is, the internal power utilization system shown in fig. 4. Here, although fig. 4 shows the alternating voltages and frequencies, it is only an example given for the purpose of facilitating an intuitive understanding of the function of the variable frequency power extraction device, and it is understood that the variable frequency power extraction device according to the exemplary embodiment of the present application may be applied to wind power generation systems of other parameters.

As shown in fig. 5, the variable frequency power taking apparatus 100 according to an exemplary embodiment of the present application may include a rectifying circuit 110, a chopper boost circuit 120, and an inverter circuit 130.

The output side of the rectifying circuit 110 may be connected to the input side of the chopper boost circuit 120, the output side of the chopper boost circuit 120 may be connected to the input side of the inverter circuit 130, the inverter circuit 130 is configured to implement an inversion function of direct current to alternating current, and the output frequency of the inverter circuit 130 may be higher than the frequency of the alternating current bus. In this way, the variable frequency power extraction device 100 can achieve an up-conversion of the power from the ac bus of the wind turbine generator system.

The variable frequency power extraction device 100 can perform frequency conversion and voltage transformation on electricity from an ac bus of a wind generating set, and supply the converted and voltage transformed electricity to an internal electricity utilization system of the wind generating set, so that even in the case that the output electricity frequency of the wind generating set is lower than the electricity utilization frequency of an electrical component, such as shown in fig. 3, the power supply to other electrical components inside the wind generating set through the wind generating set can be realized, thereby simplifying the structure of the whole wind generating set and saving the cost.

As an example, as shown in fig. 4, the wind power generation set may include a blade 41, a generator 42, a rectifying unit 43, an inverting unit 44, and a boosting power transforming unit 45, wherein a first bus bar switch Q1 and a second bus bar switch Q2 may be provided on an ac bus of the wind power generation set. As an example, an ac power of 690V voltage and 20Hz frequency may be output from an ac bus of a wind turbine generator, while the power demand of an internal power system of a wind turbine generator may be an ac power of 380V voltage and 50Hz frequency. Thus, by the variable frequency power extraction device 100, ac power from the ac bus of the wind turbine generator can be variable frequency and transformed and supplied to the internal power system.

According to an exemplary embodiment of the present application, the number of phases of the rectifying circuit 110 on the input side may be n times the number of phases of an ac bus of the wind turbine generator set, n being an integer greater than or equal to 2, and for example, the ac power from the ac bus may be converted by, for example, a phase shifter and then input to the rectifying circuit 110, however, the manner of converting the number of phases of the ac power is not limited thereto, and may be implemented in any other manner, for example, by a phase-shifting transformer 140 which will be described later.

Further, the number of legs of chopper boost circuit 120 may be an integer multiple of 3, including 3 legs as shown in fig. 6, for example, but it is not limited thereto and may include 6 legs or more. Each leg of chopper boost circuit 120 may include a switch T, a diode D, and an inductance L, wherein diode D and inductance L may be connected in series between an input side and an output side of chopper boost circuit 120, one end of switch T being connected to a connection line between diode D and inductance L, and the other end of switch T being connected between the input side and the output side of chopper boost circuit 120. Here, the switch T may be an Insulated Gate Bipolar Transistor (IGBT), as an example.

Therefore, multiple rectification is realized by setting the relation between the input side phase number of the rectifying circuit and the alternating current bus phase number, and the self-power supply can be realized by adopting the chopping boost circuit of multiple bridge arms, and the harmonic cost can be gradually reduced, the harmonic is better suppressed, the quality of a high-quality power supply at the load side of the wind power generator unit is ensured, and high-quality electric energy is provided for the internal load of the wind power generator unit by using the multiple conversion scheme of combining the multiple rectification with the chopping boost circuit of multiple bridge arms.

Fig. 6 shows a schematic structural diagram of a variable frequency electricity extraction device of a wind power generation system according to an exemplary embodiment of the present application. As shown in fig. 6, the rectifying circuit 110 may be an uncontrolled rectifying circuit, for example, may be a diode-based uncontrolled rectifying circuit. Specifically, the rectifying circuit 110 may include a plurality of diode units connected in parallel, and the number of diode units may be equal to the number of input-side phases of the rectifying circuit. Each diode unit comprises two diodes connected in series, the junction between the two diodes of each diode unit being used as a phase input to the rectifying circuit.

In the embodiment of fig. 6, a topology structure of a double 3-phase (i.e., 6 windings are mutually different by 60 degrees, instead of 120 degrees) uncontrolled rectifying circuit and a triple staggered parallel chopper boost circuit (i.e., mutually different by 120 degrees) can be adopted, so that the inductance current-resistant value can be effectively reduced, the output side direct current voltage is stabilized, and meanwhile, the topology structure can also reduce direct current ripple and improve the equipment output side power quality. However, fig. 6 is merely an example, and the present application is not limited thereto, and for example, the rectifying circuit may be an active rectifying circuit, such as a rectifying circuit based on an IGBT insulated gate bipolar transistor, and for example, the number of pulses or the number of phases of the rectifying circuit may be increased.

In addition, the inverter circuit 130 may change the output frequency by inverting pulse width modulation. As an example, the number of legs of inverter circuit 130 may be greater than or equal to 2. Therefore, a further multiple conversion scheme of combining the multiple rectification and multiple bridge arm chopping boost circuit with the multiple bridge arm inverter circuit can be realized, so that the harmonic cost can be further reduced, the electric energy quality after conversion can be improved, and high-quality electric energy can be provided for the internal load of the wind generating set.

As shown in fig. 6, the inverter circuit 130 may adopt a double-staggered parallel inverter structure with a mutual difference of 180 degrees, so that harmonics can be effectively reduced.

Specifically, the inverter circuit 130 may include a plurality of bridge arm units and a plurality of inductors, and the bridge arm units are connected in one-to-one correspondence with the inductors. Each leg unit may include an upper leg 131 and a lower leg 132 connected in series, with the plurality of leg units connected in parallel with each other. One end of the inductor corresponding to the arm unit may be connected between the upper arm 131 and the lower arm 132, and the other end thereof may be connected to the output side of the inverter circuit 130. Each leg may include an IGBT and a diode connected in parallel. By adopting the staggered parallel inversion structure of the upper and lower double bridge arms as shown in fig. 6, the output side harmonic wave of the variable-frequency power taking device 100 can be effectively reduced, and the electric energy quality can be further improved.

As an example, as shown in fig. 5, the variable frequency power taking device 100 may further include a phase shifting transformer 140. The input side of the phase-shifting transformer 140 may be used as the input side of the variable frequency power taking device 100, where the number of phases of the output side of the phase-shifting transformer 140 may be equal to the number of phases of the input side of the rectifying circuit 110, for example, may be 6, however, the application is not limited thereto, and the number of phases of the output side of the phase-shifting transformer 140 may be further increased (for example, by increasing the number of windings) according to actual needs, for example, 9, 12, etc.

The number of output side phases of the phase-shifting transformer 140 may be an integer multiple of the number of input side phases (or the number of phases of an ac bus of the wind generating set), so that multi-pulse rectification of the back-end rectifying circuit may be realized, for example, the phase-shifting transformers 140 with 9 windings and 12 windings may respectively correspond to 18 pulse wave rectification and 24 pulse wave rectification.

Here, an optimal balance value between the increase in cost and the performance due to the increase in the number of windings and the increase in the number of pulses can be reversely calculated and determined according to the power quality index on the wind turbine side. For example, the phase-shifting transformer 140 shown in fig. 5 is a six-phase winding that outputs phase-shifting phase, so that the back-end rectifying circuit can output 12 pulse dc voltage, reduce dc ripple, and provide contribution to the power quality of the wind turbine generator side of the whole system.

In addition, the phase-shifting transformer 140 may step down the voltage from the ac bus, for example, may change 690V voltage to 400V voltage, which may be advantageous in reducing the overall cost of the back-end inverter.

As an example, the phase-shifting transformer 140 may be an isolation transformer to perform a double-sided isolation function, so as to realize double-sided electrical isolation of the transformer, avoid abnormal electrical quantity injection such as high voltage and harmonic waves on the grid side, ensure reliable and stable operation of the wind generating set on power supply of electrical components inside the wind generating system even under the condition of high/low voltage faults on the grid side, and for example, can meet the technical requirements of GB/T19963-2021.

As an example, as shown in fig. 5, the variable frequency power take-off device 100 may further include a precharge protection circuit 150. An input side of the precharge protection circuit 150 may be connected to an output side of the phase-shifting transformer 140, and an output side of the precharge protection circuit 150 may be connected to an input side of the rectifying circuit 110. By arranging the precharge protection circuit 150, when the frequency conversion power taking device 100 powers on the power supply system side, the risk that the direct current capacitor in the rectifying circuit 110 is equivalent to a short circuit and possibly causes very large instantaneous heavy current due to the fact that the impedance between the access point and the direct current capacitor is very small can be avoided, the equipment safety is improved, and the heavy current is prevented from damaging equipment.

The specific structure of the precharge protection circuit 150 is shown in fig. 6, and as shown in fig. 6, the precharge protection circuit 150 may be formed based on a series resistance, and in particular, the precharge protection circuit 150 may include a protection resistance R connected in series with the first switch K1, a first switch K1, and a second switch K2 connected in parallel with the protection resistance R connected in series with the first switch K1. Before the power utilization system is electrified, the first switch K1 can be closed to realize the precharge; after the precharge is completed, the second switch K2 may be closed to power up the power system. In this way, the technology of the precharge protection circuit based on the series resistance is mature and reliable and the cost is low.

As an example, as shown in fig. 5, the variable frequency power taking device 100 may further include a machine side transformer 160, and an output side of the machine side transformer 160 may be an output side of the variable frequency power taking device 100. Here, the machine side transformer 160 may be an isolation transformer. Here, the machine side transformer 160 may perform a double-sided electrical isolation function, which is used in combination with the phase-shifting transformer 140, so that the output side and the output side of the variable-frequency power-taking device 100 are both electrically isolated from each other, so as to further avoid the influence of various working conditions from the grid side on the internal load of the wind turbine, for example, avoid the influence of the change of the power quality of the grid side on the internal load of the wind turbine.

As an example, as shown in fig. 5, the variable frequency power taking apparatus 100 may further include a filter circuit 170, an output side of the inverter circuit 130 may be connected to an input side of the filter circuit 170, and an output side of the filter circuit 170 may be connected to an input side of the side transformer 160.

As an example, the filter circuit 170 may be an LC filter circuit. Here, by using the LC filter circuit in combination with the machine side transformer 160, the inductance value of the isolation transformer on the wind turbine generator side (i.e., the output side of the variable frequency power supply device 100) can be considered, so that the total harmonic distortion rate on the output side can be further reduced, and a qualified power supply can be provided for the load on the wind turbine generator side.

It should be noted that, although components such as a rectifying circuit, a chopper boost circuit, an inverter circuit, a phase shift transformer, a side transformer, a precharge circuit, a filter circuit, and the like in the variable frequency power taking device are described by way of example in the above respective examples, the embodiments of the present application are not limited thereto, and these components may be formed in other manners as long as the respective functions thereof can be realized.

According to a second aspect of the present application, a wind power generation system is provided, which may comprise a variable frequency power extraction device as described above.

As an example, the wind power generation system may be an offshore wind power generation system as shown in fig. 3.

Furthermore, the wind power generation system may also comprise a low frequency wind power generator set, which may refer to a wind power generator set with an ac bus frequency of less than 50Hz, e.g. the ac bus frequency of the low frequency wind power generator set may be 20Hz, or any frequency around 1/3 of the frequency of 50Hz.

Here, the variable frequency electricity taking device according to the exemplary embodiment of the application is applied to the offshore wind power full LF-HVDC sending scheme, and can achieve electricity taking from a low frequency wind power system according to the internal electricity consumption requirement of a wind turbine generator, for example, achieve variable frequency electricity taking required by obtaining 50Hz load energy consumption in the wind turbine generator from a 20Hz system. Based on the frequency conversion electricity taking device, a low-frequency wind turbine generator system scheme shown in the figure 3 has technical feasibility, and technical barriers in wind power technology development are solved.

According to the variable-frequency power taking device of the wind power generation system and the wind power generation system, which are disclosed by the embodiment of the application, a multiple conversion scheme of combining double uncontrollable rectification, triple chopping boosting and double inversion is adopted, so that the harmonic cost is gradually reduced, the quality of a high-quality power supply on the load side of the wind power generator side is ensured, and high-quality electric energy is provided for the internal load of the wind power generator.

In addition, according to the variable-frequency power taking device of the wind power generation system and the wind power generation system, the uncontrolled rectification scheme based on the diodes is used, so that the cost is low, the size is small, and the control is relatively simple.

In addition, according to the variable-frequency power taking device of the wind power generation system and the wind power generation system of the exemplary embodiment of the application, the multi-pulse uncontrollable wave rectification at the rear end of the wind power generation system can be realized by adopting the phase-shifting transformer.

In addition, according to the variable-frequency electricity taking device of the wind power generation system and the wind power generation system, electric isolation between the power grid side and the internal load of the wind turbine generator is achieved through the isolation transformers on the two sides, and safety is improved.

The described features, structures, or characteristics of the application may be combined in any suitable manner in one or more embodiments. In the above description, numerous specific details are provided to give a thorough understanding of embodiments of the present application. One skilled in the relevant art will recognize, however, that the aspects of the application can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the application.

Furthermore, it should be noted that, although examples of the variable frequency power extraction device of the wind power generation system and the components of the wind power generation system are described above with reference to the specific drawings, it should be understood that the embodiments of the present application are not limited to the combinations given in the examples, and the components appearing in the different drawings may be combined, and are not exhaustive herein.

While certain embodiments have been shown and described, it would be appreciated by those skilled in the art that changes and modifications may be made to these embodiments without departing from the principles and spirit of the application, the scope of which is defined in the claims and their equivalents.

Claims (10)

1. A variable frequency electricity taking device of a wind power generation system is characterized in that the input side of the variable frequency electricity taking device is connected to an alternating current bus of a wind generating set in the wind power generation system, the output side of the variable frequency electricity taking device is connected to an electric component of the wind power generation system,

wherein the variable-frequency power taking device comprises a rectifying circuit, a chopping boost circuit and an inverter circuit, the output side of the rectifying circuit is connected to the input side of the chopping boost circuit, the output side of the chopping boost circuit is connected to the input side of the inverter circuit,

the input side phase number of the rectifying circuit is n times of the alternating current bus phase number, n is an integer greater than or equal to 2, and the number of bridge arms of the chopper boost circuit is an integer multiple of 3.

2. The variable frequency power extraction device of claim 1, wherein the number of legs of the inverter circuit is greater than or equal to 2.

3. The variable frequency power extraction device of claim 1, further comprising a phase-shifting transformer having an input side as an input side of the variable frequency power extraction device, wherein the number of output side phases of the phase-shifting transformer is equal to the number of input side phases of the rectifying circuit.

4. A variable frequency power extraction apparatus as claimed in claim 3, wherein the phase-shifting transformer is an isolation transformer.

5. A variable frequency power extraction apparatus according to claim 3, further comprising a precharge protection circuit having an input side connected to the output side of the phase-shifting transformer and an output side connected to the input side of the rectifying circuit.

6. The variable frequency power taking device of claim 1, wherein the rectifying circuit is an uncontrolled rectifying circuit.

7. The variable frequency power extraction device of any one of claims 1 to 6, further comprising a machine side transformer, an output side of the machine side transformer being an output side of the variable frequency power extraction device, wherein the machine side transformer is an isolation transformer.

8. The variable frequency power extraction device of claim 7, further comprising a filter circuit, the inverter circuit being connected to the filter circuit, an output side of the filter circuit being connected to an input side of the machine side transformer, wherein the filter circuit is an LC filter circuit.

9. A wind power generation system, characterized in that it comprises a variable frequency electricity extraction device according to any one of claims 1-8.

10. The wind power generation system of claim 9, further comprising a low frequency wind power generator set having an ac bus frequency of less than 50hz.