WO2013067800A1 - Megawatt direct drive type squirrel-cage asynchronous generator ac-dc-ac wind generation system - Google Patents

Megawatt direct drive type squirrel-cage asynchronous generator ac-dc-ac wind generation system Download PDF

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Publication number
WO2013067800A1
WO2013067800A1 PCT/CN2012/074353 CN2012074353W WO2013067800A1 WO 2013067800 A1 WO2013067800 A1 WO 2013067800A1 CN 2012074353 W CN2012074353 W CN 2012074353W WO 2013067800 A1 WO2013067800 A1 WO 2013067800A1
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WIPO (PCT)
Prior art keywords
phase
squirrel
asynchronous generator
cage asynchronous
megawatt
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PCT/CN2012/074353
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French (fr)
Chinese (zh)
Inventor
李兴
白德芳
郭自勇
王文举
龙浩
王丹
于长义
丁雅丽
王绪宝
孙贤大
崔效毓
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荣信电力电子股份有限公司
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Publication of WO2013067800A1 publication Critical patent/WO2013067800A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/10—Flexible AC transmission systems [FACTS]

Definitions

  • the invention relates to a wind power generation system, in particular to a megawatt-level direct drive type squirrel cage asynchronous generator AC-DC-AC wind power generation system using a medium voltage squirrel cage asynchronous generator as a wind power generator.
  • the existing wind power generation systems in China mainly use two types of wind power generation technologies: direct drive type and double feed type.
  • the wind turbines of direct-drive wind power technology mainly use permanent magnet synchronous generators.
  • the main disadvantages are: The price of permanent magnet materials soars, which leads to a significant increase in the cost of manufacturing permanent magnet synchronous generators, which seriously affects the construction cost and wind power of wind farms.
  • Doubly-fed wind power technology adopts wire-wound rotor asynchronous generator.
  • its cost is low and the weight is light, due to the existence of a speed-increasing gear box, and the motor itself has a brush, the reliability of the system operation is caused. Low, especially for a long time, it is difficult to solve the problem that the wind power generation system cannot operate normally due to the occasional drop of the grid voltage, making it difficult for the wind power generation system to achieve the low voltage ride
  • the object of the present invention is to provide a megawatt-level direct-drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system, which adopts a medium-voltage squirrel-cage asynchronous generator, which is small in size, light in weight and convenient to install. Maintenance-free; voltage level is medium voltage; no need to increase gearbox and brush, etc., can increase the capacity of wind power generation system to a greater extent, reduce the difficulty and cost of manufacturing large-capacity motor, improve system reliability, and facilitate low voltage Crossing function.
  • the invention adopts the power unit series technology based on the full-control type power switching device, so that the voltage level is raised to the medium voltage, the system withstands the current level is greatly reduced, and when the grid has a transient voltage drop failure, it can provide a higher support to the power grid.
  • the AC-DC-AC converter of the power generation system has the function of a dynamic var generator, which can compensate the reactive power of the grid in real time and effectively.
  • a megawatt direct drive type squirrel cage asynchronous generator AC-DC-AC wind power generation system including squirrel cage asynchronous generator, megawatt four quadrant intersection-straight An alternating current transformer and a phase shifting transformer;
  • the megawatt four-quadrant AC-DC-AC converter is composed of three converter chains, each of which is composed of a plurality of power units connected in series, and the power of the chain head
  • the unit is connected to the one-phase stator winding of the squirrel cage asynchronous generator, and the power units of the three chain tails are connected together;
  • the output end of each power unit in each converter chain is connected to the secondary winding of the corresponding phase of the phase shifting transformer, and the moving
  • the core of the phase transformer is coupled to the primary three-phase winding of the phase shifting transformer, and the primary three-phase winding of the phase shifting transformer is respectively connected to the three phases of the power grid.
  • the power unit includes an H-bridge rectifier module, a DC support capacitor, a chopper brake module, and a three-phase inverter module; the two DC output ends of the H-bridge rectifier module are respectively connected to the two poles of the DC support capacitor; Dynamic model a DC end of the block and the three-phase inverter module, and a three-phase AC output of the three-phase inverter module is connected to the three-phase filter reactor; the input end of the H-bridge rectifier module is used to connect the stator winding of the squirrel-cage asynchronous generator or A series connection of each power unit; the three-phase filter reactor is an output end of each power unit.
  • the H-bridge rectifier module is a double-half bridge structure composed of a fully-controlled power switching device, and each half-bridge includes two fully-controlled power switching devices, and the connection points of two fully-controlled power switching devices on each half-bridge are used as The input end of the H-bridge rectifier module, the fully-controlled power switching device is connected in parallel with a freewheeling diode.
  • the chopper braking module is composed of a full control power switching device and a braking resistor connected in series, and the full control power switching device and the braking resistor are connected in parallel with a freewheeling diode.
  • the three-phase inverter module is composed of a full-control power switching device, and has three half-bridge structures. Each half-bridge includes two full-control power switching devices, and the connection points of two fully-controlled power switching devices on each half-bridge are three. One of the three AC output terminals of the phase inverter module, the full control power switching device is connected in parallel with a freewheeling diode.
  • the power unit of the chain head can be connected to the one-phase stator winding of the squirrel-cage asynchronous generator through a filter reactor.
  • the squirrel cage asynchronous generator uses a medium voltage squirrel cage asynchronous generator.
  • the megawatt four-quadrant AC-DC-AC converter has a corresponding number of converter chains.
  • the present invention has significant advantages in the following aspects:
  • squirrel cage asynchronous generator is small in size, light in weight, easy to install, maintenance-free, low in cost and high in reliability, which can reduce the new power generation system. Add a lot of problems in structure and mechanical endurance.
  • the direct-drive medium-voltage squirrel-cage asynchronous generator AC-DC-AC wind power generation system adopts no-speed gearbox design, no gearbox oil leakage, oil leakage and gear teeth.
  • the fracture problem is extremely reliable and facilitates low voltage ride through.
  • Three-phase or multi-phase medium-voltage squirrel cage asynchronous generator Under the same power condition, the system can withstand the current level, which can increase the capacity of the wind power generation system to a greater extent and reduce the difficulty and cost of manufacturing large-capacity motors.
  • the megawatt direct-drive AC-DC-AC converter adopts multiple power units in series to realize multi-level output, which greatly improves the output power quality and reduces the pollution of the wind power system to the power grid.
  • variable-current chain structure of the MW-class direct-drive AC-DC-AC converter facilitates high-voltage output.
  • the megawatt direct-drive AC-DC-AC converter can double as a dynamic var generator to provide support and compensation to the grid.
  • Figure 1 is a schematic view of electrical connections of the present invention
  • FIG. 2 is a schematic diagram showing the electrical structure of a basic power unit of a megawatt direct-drive type AC-DC-AC converter
  • FIG. 3 is a schematic diagram of an H-bridge rectifier module
  • FIG. 4 is a schematic diagram of a series connection manner of a power unit H-bridge rectifier module
  • Figure 5 is a schematic diagram of the connection mode with the multiphase squirrel cage asynchronous generator
  • Figure 6 is a control block diagram of the three-phase grid side inverter module of B, C, and C;
  • FIG. 7 is a block diagram of the side control of the medium voltage squirrel cage asynchronous generator. detailed description
  • Megawatt-class direct-drive squirrel cage asynchronous generator AC-DC-AC wind power generation system including medium voltage squirrel cage asynchronous generator, MW four-quadrant AC-DC-AC converter, phase shifting transformer, mechanical transmission part Adopt no gearbox design.
  • the megawatt four-quadrant AC-DC-AC converter is a chain structure composed of a plurality of power units connected in series, each phase being a converter chain; one ends of the three converter chains are connected to form the three The star-neutral point of the phase, the other end of the three converter chains is connected to the stator winding corresponding to the squirrel cage asynchronous generator; the squirrel cage asynchronous generator emits three-phase alternating current, and the power unit rectifier module in each phase change chain
  • the rectification is converted into direct current, and then the direct current is converted into alternating current by the inverter module of the power unit, and the three-phase alternating current output end of each power unit in each converter chain is connected to the secondary winding of the corresponding phase of the phase shifting transformer;
  • the core of the phase transformer is coupled to the primary three-phase winding of the phase shifting transformer, and the three-phase windings of the primary side of the transformer are respectively connected with the three-phase B, B and C of the power grid to realize the transmission of medium and high
  • the output voltage level of the squirrel cage asynchronous generator determines the number of power units connected in series for each phase. Each phase consists of n power units. Therefore, the megawatt direct-drive AC-DC converter includes 3n power units. .
  • a four-quadrant AC-DC converter with three-phase medium-voltage squirrel-cage asynchronous generators requires three converter chains. One ends of the three converter chains are connected to form a star-neutral point of the three-phase. The other end of the three converter chains passes through the filter reactor (if the stator leakage resistance of the generator is large and the du/dt withstand capability is strong, the filter reactor may not be used) and the stator corresponding to the medium voltage squirrel cage asynchronous generator The windings are connected.
  • a megawatt direct-drive AC-DC-AC converter for use with a medium-voltage squirrel-cage asynchronous generator, including several power units, each H-bridge rectifier module, DC support capacitor , Chopper brake module and three-phase inverter module.
  • the H-bridge rectifier module consists of a fully-controlled power switching device consisting of two half-bridge structures. Each half-bridge contains two fully-controlled power switching devices. The connection point of two fully-controlled power switching devices on each half-bridge is used as an H-bridge.
  • the full control power switching device is connected in parallel with the freewheeling diode
  • the chopper braking module is composed of a full control power switching device and a braking resistor in series, wherein the fully controlled power switching device and system The dynamic resistance is connected in parallel with the freewheeling diode
  • the three-phase inverter module is composed of a full-control power switching device composed of three half-bridge structures, each half-bridge includes two fully-controlled power switching devices, and two full-control powers on each half-bridge
  • the connection point of the switching device is one of three AC output terminals of the three-phase inverter module, wherein the full control power switching device is connected in parallel with the freewheeling diode.
  • each H-bridge rectifier module The two DC output ends of each H-bridge rectifier module are respectively connected to the two poles of the DC supporting capacitor; then, the braking module connected in series with the braking resistor by the fully-controlled power switching device is connected, and then the DC terminal of the three-phase inverter module is connected. Finally, the three-phase AC output of the three-phase inverter module is connected to the three-phase filter reactor.
  • the rectifier module adopts an H-bridge structure.
  • the connection point of two fully-controlled power switching devices on each half-bridge is one of the two input terminals of the H-bridge circuit, which are defined as input terminal 1 and input terminal 2, respectively.
  • the two input terminals 1 and 2 of the n H-bridge rectifier modules are alternately connected in sequence to form a converter chain as one of the three phases.
  • a four-quadrant AC-DC converter with three-phase medium-voltage squirrel-cage asynchronous generators requires three converter chains. One ends of the three converter chains are connected to form a star-neutral point of the three-phase. The other end of the three converter chains passes through the filter reactor (if the stator leakage resistance of the generator is large and the du/dt withstand capability is strong, the filter reactor may not be used) and the stator corresponding to the medium voltage squirrel cage asynchronous generator The windings are connected.
  • the megawatt four-quadrant AC-DC-AC converter is used with a multi-phase squirrel cage asynchronous generator. For example, if a medium-voltage squirrel-cage asynchronous generator with M sets of three-phase stator windings is used, the MW-class four-quadrant AC-DC-AC converter with a total of 3M converter chains, each three converters One end of the chain is joined together to form a three-phase star Neutral point, the other end of each of the three converter chains passes through the filter reactor (if the stator leakage resistance of the generator is large and the du/dt withstand capability is strong, the filter reactor may not be used) the stator winding corresponding to the generator Connected.
  • the filter reactor if the stator leakage resistance of the generator is large and the du/dt withstand capability is strong, the filter reactor may not be used
  • the control of the grid-side inverter module uses a double closed-loop structure in which the current is the inner loop and the voltage loop is the outer loop.
  • the voltage loop (outer loop) is used to maintain the constant DC voltage of the unit as the control target.
  • the current loop (inner loop) is used to quickly follow the current reference, and the inverter current is sinusoidal and the power factor angle can be adjusted to the control target.
  • the grid-side three-phase inverter currents iga, igb, and igc are decoupled active current igq and reactive current igd by Clarke transform and Park transform.
  • the active current igq is compared with the active current of the voltage loop output given by igq*, and is output ugq after being processed by the active current regulator PI.
  • the reactive current igd is compared with the reactive current set by the system given igd*, and the reactive current is adjusted.
  • the UGd is output after the PI processing.
  • the ugq characterizing the active current and the ugd characterizing the reactive current are inversely transformed by Park to generate the modulation voltages ug ⁇ and ug ⁇ in the two-phase stationary coordinate system, and then the PWM drive of the corresponding fully-controlled power switching device on the inverter module is generated by SVPWM.
  • the active current of the voltage loop output is given.
  • igq* is the output of the voltage closed-loop negative feedback, which always makes the inner loop of the current follow the direction adjustment of the voltage.
  • Reactive current reference igd* is the settable amount required by the system to regulate the reactive power level of the inverter to the grid side.
  • the Park inverse transform generates a sinusoidal modulated signal. Therefore, the voltage outer loop can ensure that the voltage is constant, and the current inner loop can realize the artificial regulation of the inverter current sinusoidal and the inverter reactive component.
  • the main generator side rectifier is to quickly follow the power or current reference of the wind power main control system to realize the sinusoidal rectification current and the rectified power factor angle.
  • the three-phase rectified currents ima, imb, and imc on the generator side are transformed by Clarke and Park to obtain the active and reactive decoupling currents imq and imd.
  • the active current imq is compared with the active current from the main control system given imq*, and the output current umq is processed by the active current regulator PI, and the reactive current imq is compared with the reactive current set by the system to give imd*, the reactive current
  • the regulator PI processes and outputs umd.
  • the umq characterizing the active current and the umd characterizing the reactive current are inversely transformed by Park to generate the modulation voltages um a and um P in the two-phase stationary coordinate system, and then the generator side ABC three-phase modulation voltage uma is generated by the modulated wave generator.
  • Umb, umc, three-phase modulation voltage uma, umb, umc are compared with the respective phase-shifting carriers, and the PWM driving signals of the corresponding IGBTs of the rectifier modules of each phase of the machine side are generated, the phase A is PWMmal ⁇ PWMman, and the phase B is PWMmbl ⁇ PWMmbn, Phase C is PWMmcl ⁇ PWMmcn.
  • Reactive current reference imd* is the settable amount required by the system to adjust the power factor angle of the machine side rectification.
  • the Park inverse transform generates a sinusoidal modulation signal, and the current loop can realize the artificial adjustment of the machine side rectified current sinusoidal and the machine side rectified power factor angle.
  • the blade directly drives the medium voltage squirrel cage asynchronous generator to rotate, when the fundamental frequency generated by the motor side of the AC-DC-AC converter is lower than the electric frequency corresponding to the current speed of the medium voltage squirrel cage asynchronous generator (ie The slip frequency of the generator is negative), the squirrel cage asynchronous generator works in the power generation state, and the output power of the generator can be controlled by controlling the slip of the generator and the stator voltage; the alternating current generated by the squirrel cage asynchronous generator is respectively made by each H
  • the bridge rectifier module is converted into the DC power of the H-bridge rectifier module; the respective DC power of the H-bridge rectifier module is converted into a three-phase power frequency AC power by the respective three-phase inverter module, and is applied to the corresponding secondary winding of the phase shifting transformer, thereby moving
  • the core of the phase transformer is coupled to the primary three-phase winding of the phase shifting transformer.
  • the three-phase windings of the primary side of the transformer are connected to the three-phase windings of the power grid, B and C, respectively, to realize the transmission of electrical energy to the power grid.
  • the fully controlled power switching device in the chopper braking module is automatically turned on, through the braking resistor Excessive energy is consumed so that the voltage of the DC supporting capacitor is limited to not exceed a prescribed threshold.
  • the wind power generation system can adopt medium voltage or even high pressure squirrel cage of various voltage levels.
  • Asynchronous generator become possible. Thanks to medium-voltage or even high-voltage three-phase or multi-phase squirrel cage asynchronous generators, and the matching AC-DC-AC converters, it is possible to realize a more powerful wind power system;
  • the AC-type converter has the same power as the wind turbine, the adoption of the chopper braking module, and the direct coupling between the wind turbine and the grid, making it easier for the wind power system to achieve low voltage ride-through function;
  • the three-phase inverter module of the direct-interchange converter and the DC support capacitor structure constitute the key elements of the main circuit topology of the dynamic var generator, so the wind power generation system can also double as a dynamic var generator, which can be used for the grid. Reactive power is compensated in real time and effectively.

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  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

A megawatt direct drive type squirrel-cage asynchronous generator AC-DC-AC wind generation system with a medium-voltage squirrel-cage asynchronous generator as a wind generator comprises a squirrel-cage asynchronous generator, a megawatt four-quadrant AC-DC-AC converter and a phase-shifting transformer. The converter is configured by converter chains composed of three power units connected in series. One end of each converter chains is connected together, and the other end of each converter chain is connected to the stator windings of the corresponding phase of the squirrel-cage asynchronous generator. The output terminal of each power unit in every converter chain is connected to the secondary windings of the corresponding phase of the phase-shifting transformer, and the primary-side three-phase windings of the phase-shifting transformer are connected with the three phases of the power grid. The wind generation system uses a medium-voltage squirrel-cage asynchronous generator, has small size, light weight, easy installment, free maintenance, no increasing gearbox and brush, and can improve the capacity of the wind generation system, reduce the difficulty and cost of manufacturing a large-capacity motor, improve system reliability, and be easy to low voltage ride through.

Description

兆瓦级直驱型鼠笼异步发电机交-直-交风力发电*** 技术领域  Megawatt-class direct drive type squirrel cage asynchronous generator AC-DC-AC wind power generation system
本发明涉及风力发电***， 特别涉及一种以中压鼠笼异步发电机作为风力发电 机的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***。 背景技术  The invention relates to a wind power generation system, in particular to a megawatt-level direct drive type squirrel cage asynchronous generator AC-DC-AC wind power generation system using a medium voltage squirrel cage asynchronous generator as a wind power generator. Background technique
国内目前现有的风力发电***主要采用两种风力发电技术： 直驱型与双馈型。 直驱型风力发电技术的风力发电机主要采用永磁同步发电机，其主要缺点在于： 永磁 材料价格飞涨， 导致制造永磁同步发电机的成本大幅度上升，严重影响风电场建设成 本与风力发电方式的竞争力； 双馈型风力发电技术采用线绕转子异步发电机， 虽然其 成本低、 重量轻， 但由于存在增速齿轮箱， 且电机本身带有电刷， 导致***运行的可 靠性低，特别是长期以来难以解决由于电网电压偶尔跌落而使风力发电***无法正常 运行的问题， 使风力发电***难以实现低电压穿越功能。  At present, the existing wind power generation systems in China mainly use two types of wind power generation technologies: direct drive type and double feed type. The wind turbines of direct-drive wind power technology mainly use permanent magnet synchronous generators. The main disadvantages are: The price of permanent magnet materials soars, which leads to a significant increase in the cost of manufacturing permanent magnet synchronous generators, which seriously affects the construction cost and wind power of wind farms. Competitiveness of power generation mode; Doubly-fed wind power technology adopts wire-wound rotor asynchronous generator. Although its cost is low and the weight is light, due to the existence of a speed-increasing gear box, and the motor itself has a brush, the reliability of the system operation is caused. Low, especially for a long time, it is difficult to solve the problem that the wind power generation system cannot operate normally due to the occasional drop of the grid voltage, making it difficult for the wind power generation system to achieve the low voltage ride through function.
为了解决永磁同步发电机成本高的问题， 有人提出采用电励磁同步发电机替代 永磁同步发电机的设想。然而在相同功率等级下， 电励磁同步发电机要远比永磁同步 电机重量重很多， 给风力发电***新增许多结构、机械承受力方面的问题； 而且由于 有刷式电励磁同步发电机带有电刷， 影响了风力发电***运行的可靠性， 而无刷式电 励磁同步发电机长度更长、 重量更重， 导致结构与机械承受力方面的问题更加突出。 发明内容  In order to solve the problem of high cost of permanent magnet synchronous generators, the idea of using an electric excitation synchronous generator instead of a permanent magnet synchronous generator has been proposed. However, under the same power level, the electric excitation synchronous generator is much heavier than the permanent magnet synchronous motor, adding many structural and mechanical bearing problems to the wind power generation system; and because of the brushed electric excitation synchronous generator belt Brushes affect the reliability of wind power system operation, while brushless electric field synchronous generators have longer lengths and heavier weights, which leads to more serious problems in structural and mechanical endurance. Summary of the invention
本发明的目的是提供一种兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 该风力发电***采用中压鼠笼异步发电机， 尺寸小、 重量轻、 安装方便、 免维护； 电 压等级为中压； 无需增速齿轮箱与电刷等特点， 可以更大限度提高风力发电***的容 量，降低制造大容量电机的难度与成本，提高***可靠性，便于实现低电压穿越功能。  The object of the present invention is to provide a megawatt-level direct-drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system, which adopts a medium-voltage squirrel-cage asynchronous generator, which is small in size, light in weight and convenient to install. Maintenance-free; voltage level is medium voltage; no need to increase gearbox and brush, etc., can increase the capacity of wind power generation system to a greater extent, reduce the difficulty and cost of manufacturing large-capacity motor, improve system reliability, and facilitate low voltage Crossing function.
本发明采用基于全控型功率开关器件的功率单元串联技术， 使电压等级升高至中 压， ***承受电流等级大大降低， 当电网出现瞬时电压跌落故障时， 可提供更高的对 电网的支撑能力，提高了风力发电***的运行的安全性与可靠性； 同时多功率单元串 联的方式还可以实现多电平输出，提高输出电能质量，减少了风力发电***对电网的 污染； 此外， 该风力发电***的交 -直-交型变流器兼有动态无功发生器的功能， 可以 对电网的无功进行实时、 有效地补偿。  The invention adopts the power unit series technology based on the full-control type power switching device, so that the voltage level is raised to the medium voltage, the system withstands the current level is greatly reduced, and when the grid has a transient voltage drop failure, it can provide a higher support to the power grid. The ability to improve the safety and reliability of the operation of the wind power system; at the same time, the multi-power unit series connection can also achieve multi-level output, improve the output power quality, and reduce the pollution of the wind power system to the power grid; The AC-DC-AC converter of the power generation system has the function of a dynamic var generator, which can compensate the reactive power of the grid in real time and effectively.
为实现上述目的， 本发明通过以下技术方案实现： 一种兆瓦级直驱型鼠笼异步发 电机交-直 -交风力发电***， 包括鼠笼异步发电机、 兆瓦级四象限交-直 -交变流器和 移相变压器； 所述兆瓦级四象限交-直-交变流器由三个变流链构成， 每个变流链由多 个功率单元串联组成，链首的功率单元连接鼠笼异步发电机的一相定子绕组，三个链 尾的功率单元连接在一起；每个变流链中各功率单元的输出端连接至移相变压器对应 相的副边绕组，通过移相变压器的铁心耦合至移相变压器的原边三相绕组，移相变压 器的原边三相绕组分别与电网的三相连接。  In order to achieve the above object, the present invention is achieved by the following technical solutions: A megawatt direct drive type squirrel cage asynchronous generator AC-DC-AC wind power generation system, including squirrel cage asynchronous generator, megawatt four quadrant intersection-straight An alternating current transformer and a phase shifting transformer; the megawatt four-quadrant AC-DC-AC converter is composed of three converter chains, each of which is composed of a plurality of power units connected in series, and the power of the chain head The unit is connected to the one-phase stator winding of the squirrel cage asynchronous generator, and the power units of the three chain tails are connected together; the output end of each power unit in each converter chain is connected to the secondary winding of the corresponding phase of the phase shifting transformer, and the moving The core of the phase transformer is coupled to the primary three-phase winding of the phase shifting transformer, and the primary three-phase winding of the phase shifting transformer is respectively connected to the three phases of the power grid.
所述功率单元包括 H桥整流模块、直流支撑电容、斩波制动模块和三相逆变模块; H桥整流模块的两个直流输出端与直流支撑电容的两极分别相连；再连接斩波制动模 块和三相逆变模块的直流端， 三相逆变模块的三相交流输出端连接三相滤波电抗器； 所述 H桥整流模块的输入端用于连接鼠笼异步发电机的定子绕组或各功率单元 的串联连接； 所述三相滤波电抗器为各功率单元的输出端。 The power unit includes an H-bridge rectifier module, a DC support capacitor, a chopper brake module, and a three-phase inverter module; the two DC output ends of the H-bridge rectifier module are respectively connected to the two poles of the DC support capacitor; Dynamic model a DC end of the block and the three-phase inverter module, and a three-phase AC output of the three-phase inverter module is connected to the three-phase filter reactor; the input end of the H-bridge rectifier module is used to connect the stator winding of the squirrel-cage asynchronous generator or A series connection of each power unit; the three-phase filter reactor is an output end of each power unit.
所述 H桥整流模块是由全控型功率开关器件组成双半桥结构，每个半桥上包含两 个全控功率开关器件， 每个半桥上两个全控功率开关器件的连接点作为 H桥整流模 块的输入端， 所述全控功率开关器件均并联续流二极管。  The H-bridge rectifier module is a double-half bridge structure composed of a fully-controlled power switching device, and each half-bridge includes two fully-controlled power switching devices, and the connection points of two fully-controlled power switching devices on each half-bridge are used as The input end of the H-bridge rectifier module, the fully-controlled power switching device is connected in parallel with a freewheeling diode.
所述斩波制动模块由一个全控功率开关器件和一个制动电阻串联组成， 所述全控 功率开关器件和制动电阻均并联续流二极管。  The chopper braking module is composed of a full control power switching device and a braking resistor connected in series, and the full control power switching device and the braking resistor are connected in parallel with a freewheeling diode.
所述三相逆变模块由全控功率开关器件组成三半桥结构， 每个半桥上包含两个全 控功率开关器件，每个半桥上两个全控功率开关器件的连接点作为三相逆变模块的三 个交流输出端之一， 所述全控功率开关器件均并联续流二极管。  The three-phase inverter module is composed of a full-control power switching device, and has three half-bridge structures. Each half-bridge includes two full-control power switching devices, and the connection points of two fully-controlled power switching devices on each half-bridge are three. One of the three AC output terminals of the phase inverter module, the full control power switching device is connected in parallel with a freewheeling diode.
所述链首的功率单元可通过滤波电抗器连接鼠笼异步发电机的一相定子绕组。 所述鼠笼异步发电机采用中压鼠笼异步发电机。  The power unit of the chain head can be connected to the one-phase stator winding of the squirrel-cage asynchronous generator through a filter reactor. The squirrel cage asynchronous generator uses a medium voltage squirrel cage asynchronous generator.
所述笼异步发电机具有多套三相定子绕组时， 则所述兆瓦级四象限交 -直-交变流 器具有相应套数的变流链。  When the cage asynchronous generator has multiple sets of three-phase stator windings, the megawatt four-quadrant AC-DC-AC converter has a corresponding number of converter chains.
与现有风力发电技术相比， 本发明在以下诸方面具有显著优势：  Compared with existing wind power generation technologies, the present invention has significant advantages in the following aspects:
1. 与永磁同步发电机相比，制造鼠笼异步发电机的成本远比制造永磁同步发电机 的成本低很多， 使建设风电场更具经济效益。  1. Compared with permanent magnet synchronous generators, the cost of manufacturing squirrel cage asynchronous generators is much lower than the cost of manufacturing permanent magnet synchronous generators, making the construction of wind farms more economical.
2. 与有刷电励磁同步发电机和无刷电励磁同步发电机相比，鼠笼异步发电机体积 小、重量轻、安装方便、免维护、成本低、可靠性高， 可减少发电***新增许多结构、 机械承受力方面的问题。  2. Compared with brushed electric excitation synchronous generator and brushless electric excitation synchronous generator, squirrel cage asynchronous generator is small in size, light in weight, easy to install, maintenance-free, low in cost and high in reliability, which can reduce the new power generation system. Add a lot of problems in structure and mechanical endurance.
3. 与应用双馈线绕异步发电机相比， 直驱型中压鼠笼异步发电机交-直-交风力发 电***采用无增速齿轮箱设计， 没有齿轮箱漏油、渗油和齿轮齿断裂问题， 可靠性极 高、 而且便于实现低电压穿越功能。  3. Compared with the application of double-fed-wound asynchronous generator, the direct-drive medium-voltage squirrel-cage asynchronous generator AC-DC-AC wind power generation system adopts no-speed gearbox design, no gearbox oil leakage, oil leakage and gear teeth. The fracture problem is extremely reliable and facilitates low voltage ride through.
4. 采用三相或多相中压的鼠笼异步发电机， 同样功率条件下， ***承受电流等级 降低，可以更大限度地提高风力发电***的容量，降低制造大容量电机的难度与成本。  4. Three-phase or multi-phase medium-voltage squirrel cage asynchronous generator. Under the same power condition, the system can withstand the current level, which can increase the capacity of the wind power generation system to a greater extent and reduce the difficulty and cost of manufacturing large-capacity motors.
5. 兆瓦级直驱式交-直-交型变流器采用多功率单元串联的方式实现多电平输出， 大大提高了输出电能质量， 减少风力发电***对电网的污染。  5. The megawatt direct-drive AC-DC-AC converter adopts multiple power units in series to realize multi-level output, which greatly improves the output power quality and reduces the pollution of the wind power system to the power grid.
6. 兆瓦级直驱式交-直-交型变流器的变流链结构便于高电压等级的输出。  6. The variable-current chain structure of the MW-class direct-drive AC-DC-AC converter facilitates high-voltage output.
7. 兆瓦级直驱式交-直-交型变流器可兼作动态无功发生器， 对电网提供支撑和补 偿。 附图说明  7. The megawatt direct-drive AC-DC-AC converter can double as a dynamic var generator to provide support and compensation to the grid. DRAWINGS
图 1是本发明电气连接示意图；  Figure 1 is a schematic view of electrical connections of the present invention;
图 2是兆瓦级直驱型交 -直-交变流器基本功率单元电气结构示意图；  2 is a schematic diagram showing the electrical structure of a basic power unit of a megawatt direct-drive type AC-DC-AC converter;
图 3是 H桥整流模块示意图；  Figure 3 is a schematic diagram of an H-bridge rectifier module;
图 4是功率单元 H桥整流模块串联方式示意图；  4 is a schematic diagram of a series connection manner of a power unit H-bridge rectifier module;
图 5是与多相鼠笼异步发电机配套使用连接方式示意图；  Figure 5 is a schematic diagram of the connection mode with the multiphase squirrel cage asynchronous generator;
图 6是 、 B、 C三相电网侧逆变模块控制框图；  Figure 6 is a control block diagram of the three-phase grid side inverter module of B, C, and C;
图 7是中压鼠笼异步发电机侧控制框图。 具体实施方式 Figure 7 is a block diagram of the side control of the medium voltage squirrel cage asynchronous generator. detailed description
兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***，包括中压鼠笼异步发电机、 兆瓦级四象限交-直 -交变流器、 移相变压器， 机械传动部分采用无增速齿轮箱设计。  Megawatt-class direct-drive squirrel cage asynchronous generator AC-DC-AC wind power generation system, including medium voltage squirrel cage asynchronous generator, MW four-quadrant AC-DC-AC converter, phase shifting transformer, mechanical transmission part Adopt no gearbox design.
见图 1， 兆瓦级四象限交 -直-交变流器为多个功率单元串联组成的链式结构， 每 相为一个变流链； 三个变流链的一端连接在一起形成该三相的星形中性点，三个变流 链的另一端与鼠笼异步发电机对应的定子绕组相连； 鼠笼异步发电机发出三相交流 电， 经每相变流链中的功率单元整流模块整流转换成直流电， 再经该功率单元的逆变 模块将直流电转换成交流电，每个变流链中各功率单元的三相交流输出端再连接至移 相变压器对应相的副边绕组；通过移相变压器的铁心耦合至移相变压器的原边三相绕 组， 变压器的原边 A、 B、 C三相绕组分别与电网的八、 B、 C三相连接， 实现向电网 输送中高压电能。  As shown in Fig. 1, the megawatt four-quadrant AC-DC-AC converter is a chain structure composed of a plurality of power units connected in series, each phase being a converter chain; one ends of the three converter chains are connected to form the three The star-neutral point of the phase, the other end of the three converter chains is connected to the stator winding corresponding to the squirrel cage asynchronous generator; the squirrel cage asynchronous generator emits three-phase alternating current, and the power unit rectifier module in each phase change chain The rectification is converted into direct current, and then the direct current is converted into alternating current by the inverter module of the power unit, and the three-phase alternating current output end of each power unit in each converter chain is connected to the secondary winding of the corresponding phase of the phase shifting transformer; The core of the phase transformer is coupled to the primary three-phase winding of the phase shifting transformer, and the three-phase windings of the primary side of the transformer are respectively connected with the three-phase B, B and C of the power grid to realize the transmission of medium and high-voltage electric energy to the power grid.
鼠笼异步发电机输出电压等级决定了每相所串联的功率单元的数量， 每相由 n个 功率单元组成， 因此兆瓦级直驱型交-直-交变流器共包括 3n个功率单元。 与三相中 压鼠笼异步发电机配套的四象限交 -直-交变流器共需三个变流链， 三个变流链的一端 连接在一起形成该三相的星形中性点，三个变流链的另一端通过滤波电抗器（如果发 电机的定子漏抗较大且 du/dt耐受能力强， 滤波电抗器可不必采用） 与中压鼠笼异步 发电机对应的定子绕组相连。  The output voltage level of the squirrel cage asynchronous generator determines the number of power units connected in series for each phase. Each phase consists of n power units. Therefore, the megawatt direct-drive AC-DC converter includes 3n power units. . A four-quadrant AC-DC converter with three-phase medium-voltage squirrel-cage asynchronous generators requires three converter chains. One ends of the three converter chains are connected to form a star-neutral point of the three-phase. The other end of the three converter chains passes through the filter reactor (if the stator leakage resistance of the generator is large and the du/dt withstand capability is strong, the filter reactor may not be used) and the stator corresponding to the medium voltage squirrel cage asynchronous generator The windings are connected.
见图 2， 与中压鼠笼式异步发电机配套使用的兆瓦级直驱式交 -直-交型变流器， 包括若干功率单元， 每个功率单元由 H桥整流模块、 直流支撑电容、 斩波制动模块 和三相逆变模块组成。 H桥整流模块是由全控型功率开关器件组成双半桥结构， 每个 半桥上包含两个全控功率开关器件，每个半桥上两个全控功率开关器件的连接点作为 H桥整流模块的两个输入端之一， 其中全控功率开关器件均并联续流二极管； 斩波制 动模块由一个全控功率开关器件和一个制动电阻串联组成，其中全控功率开关器件与 制动电阻均并联续流二极管； 三相逆变模块是由全控功率开关器件组成三半桥结构， 每个半桥上包含两个全控功率开关器件，每个半桥上两个全控功率开关器件的连接点 作为三相逆变模块的三个交流输出端之一， 其中全控功率开关器件均并联续流二极 管。 每个 H桥整流模块的两个直流输出端与直流支撑电容的两极分别相连； 然后连 接由全控功率开关器件与制动电阻串联的制动模块， 再连接三相逆变模块的直流端， 最后三相逆变模块的三相交流输出端连接三相滤波电抗器。  See Figure 2, a megawatt direct-drive AC-DC-AC converter for use with a medium-voltage squirrel-cage asynchronous generator, including several power units, each H-bridge rectifier module, DC support capacitor , Chopper brake module and three-phase inverter module. The H-bridge rectifier module consists of a fully-controlled power switching device consisting of two half-bridge structures. Each half-bridge contains two fully-controlled power switching devices. The connection point of two fully-controlled power switching devices on each half-bridge is used as an H-bridge. One of the two input terminals of the rectifier module, wherein the full control power switching device is connected in parallel with the freewheeling diode; the chopper braking module is composed of a full control power switching device and a braking resistor in series, wherein the fully controlled power switching device and system The dynamic resistance is connected in parallel with the freewheeling diode; the three-phase inverter module is composed of a full-control power switching device composed of three half-bridge structures, each half-bridge includes two fully-controlled power switching devices, and two full-control powers on each half-bridge The connection point of the switching device is one of three AC output terminals of the three-phase inverter module, wherein the full control power switching device is connected in parallel with the freewheeling diode. The two DC output ends of each H-bridge rectifier module are respectively connected to the two poles of the DC supporting capacitor; then, the braking module connected in series with the braking resistor by the fully-controlled power switching device is connected, and then the DC terminal of the three-phase inverter module is connected. Finally, the three-phase AC output of the three-phase inverter module is connected to the three-phase filter reactor.
见图 3， 整流模块采用 H桥结构， 每个半桥上两个全控功率开关器件的连接点作 为 H桥电路的两个输入端之一， 分别定义为输入端 1与输入端 2。  As shown in Fig. 3, the rectifier module adopts an H-bridge structure. The connection point of two fully-controlled power switching devices on each half-bridge is one of the two input terminals of the H-bridge circuit, which are defined as input terminal 1 and input terminal 2, respectively.
见图 4， n个 H桥整流模块的两个输入端 1和 2依次交替连接， 构成一个变流链， 作为三相中的一相。 与三相中压鼠笼异步发电机配套的四象限交-直-交变流器共需三 个变流链，三个变流链的一端连接在一起形成该三相的星形中性点，三个变流链的另 一端通过滤波电抗器 （如果发电机的定子漏抗较大且 du/dt耐受能力强， 滤波电抗器 可不必采用） 与中压鼠笼异步发电机对应的定子绕组相连。  Referring to Figure 4, the two input terminals 1 and 2 of the n H-bridge rectifier modules are alternately connected in sequence to form a converter chain as one of the three phases. A four-quadrant AC-DC converter with three-phase medium-voltage squirrel-cage asynchronous generators requires three converter chains. One ends of the three converter chains are connected to form a star-neutral point of the three-phase. The other end of the three converter chains passes through the filter reactor (if the stator leakage resistance of the generator is large and the du/dt withstand capability is strong, the filter reactor may not be used) and the stator corresponding to the medium voltage squirrel cage asynchronous generator The windings are connected.
见图 5， 兆瓦级四象限交-直-交变流器与多相鼠笼异步发电机配套使用。 如应用 具有 M套三相定子绕组的中压鼠笼异步发电机时， 则与之配套的兆瓦级四象限交-直 -交变流器共需 3M个变流链， 每三个变流链的一端连接在一起形成一个三相的星形 中性点，每三个变流链的另一端通过滤波电抗器（如果发电机的定子漏抗较大且 du/dt 耐受能力强， 滤波电抗器可不必采用） 与发电机对应的定子绕组相连。 See Figure 5. The megawatt four-quadrant AC-DC-AC converter is used with a multi-phase squirrel cage asynchronous generator. For example, if a medium-voltage squirrel-cage asynchronous generator with M sets of three-phase stator windings is used, the MW-class four-quadrant AC-DC-AC converter with a total of 3M converter chains, each three converters One end of the chain is joined together to form a three-phase star Neutral point, the other end of each of the three converter chains passes through the filter reactor (if the stator leakage resistance of the generator is large and the du/dt withstand capability is strong, the filter reactor may not be used) the stator winding corresponding to the generator Connected.
见图 6， 电网侧逆变模块的控制采用电流为内环、 电压环为外环的双闭环结构， 电压环（外环） 以维持单元直流电压恒定为控制目标。 电流环（内环） 以快速跟随电 流给定， 实现逆变电流正弦化、 功率因数角可调为控制目标。  See Figure 6. The control of the grid-side inverter module uses a double closed-loop structure in which the current is the inner loop and the voltage loop is the outer loop. The voltage loop (outer loop) is used to maintain the constant DC voltage of the unit as the control target. The current loop (inner loop) is used to quickly follow the current reference, and the inverter current is sinusoidal and the power factor angle can be adjusted to the control target.
电网侧三相逆变电流 iga、 igb、 igc经 Clarke变换和 Park变换， 得到解耦的有功 电流 igq和无功电流 igd。有功电流 igq与电压环输出的有功电流给定 igq*比较，经有 功电流调节器 PI处理后输出 ugq， 无功电流 igd与***设定的无功电流给定 igd*比较， 经无功电流调节器 PI处理后输出 ugd。 表征有功电流的 ugq和表征无功电流的 ugd， 经 Park逆变换生成两相静止坐标系下的调制电压 ug α和 ug β，再经 SVPWM生成逆 变模块上相应全控功率开关器件的 PWM驱动信号 PWMgl〜 PWMgn。  The grid-side three-phase inverter currents iga, igb, and igc are decoupled active current igq and reactive current igd by Clarke transform and Park transform. The active current igq is compared with the active current of the voltage loop output given by igq*, and is output ugq after being processed by the active current regulator PI. The reactive current igd is compared with the reactive current set by the system given igd*, and the reactive current is adjusted. The UGd is output after the PI processing. The ugq characterizing the active current and the ugd characterizing the reactive current are inversely transformed by Park to generate the modulation voltages ug α and ug β in the two-phase stationary coordinate system, and then the PWM drive of the corresponding fully-controlled power switching device on the inverter module is generated by SVPWM. Signal PWMgl~PWMgn.
电压环输出的有功电流给定 igq*是电压闭环负反馈的输出， 总是使电流内环向电 压给定量方向跟随调节。无功电流给定 igd*是根据***需要的可设定量，用以调节向 电网侧逆变的无功含量。 Park逆变换生成的是正弦的调制信号， 因此， 电压外环能保 证电压恒定， 电流内环能实现逆变电流正弦化与逆变无功分量的人为调节。  The active current of the voltage loop output is given. igq* is the output of the voltage closed-loop negative feedback, which always makes the inner loop of the current follow the direction adjustment of the voltage. Reactive current reference igd* is the settable amount required by the system to regulate the reactive power level of the inverter to the grid side. The Park inverse transform generates a sinusoidal modulated signal. Therefore, the voltage outer loop can ensure that the voltage is constant, and the current inner loop can realize the artificial regulation of the inverter current sinusoidal and the inverter reactive component.
见图 7， 发电机侧整流器主要完成的是快速跟随风力发电主控***的功率或电流 给定，实现整流电流正弦化、整流功率因数角可调。发电机侧三相整流电流 ima、 imb、 imc经 Clarke变换和 Park变换， 得到有功、 无功解耦的电流 imq和 imd。 有功电流 imq与来自主控***的有功电流给定 imq*比较，经有功电流调节器 PI处理后输出 umq， 无功电流 imq与***设定的无功电流给定 imd*比较， 经无功电流调节器 PI处理后输 出 umd。 表征有功电流的 umq和表征无功电流的 umd， 经 Park逆变换生成两相静止 坐标系下的调制电压 um a和 um P， 再经调制波发生器生成发电机侧 ABC三相调制 电压 uma、 umb、 umc, 三相调制电压 uma、 umb、 umc与各自的移相载波比较， 生 成机侧各相各整流模块相应 IGBT的 PWM驱动信号， A相是 PWMmal〜 PWMman, B相是 PWMmbl〜PWMmbn， C相是 PWMmcl〜 PWMmcn。 无功电流给定 imd*是根 据***需要的可设定量，用以调节机侧整流的功率因数角。 Park逆变换生成的是正弦 的调制信号， 电流环能实现机侧整流电流正弦化与机侧整流功率因数角的人为调节。  See Figure 7. The main generator side rectifier is to quickly follow the power or current reference of the wind power main control system to realize the sinusoidal rectification current and the rectified power factor angle. The three-phase rectified currents ima, imb, and imc on the generator side are transformed by Clarke and Park to obtain the active and reactive decoupling currents imq and imd. The active current imq is compared with the active current from the main control system given imq*, and the output current umq is processed by the active current regulator PI, and the reactive current imq is compared with the reactive current set by the system to give imd*, the reactive current The regulator PI processes and outputs umd. The umq characterizing the active current and the umd characterizing the reactive current are inversely transformed by Park to generate the modulation voltages um a and um P in the two-phase stationary coordinate system, and then the generator side ABC three-phase modulation voltage uma is generated by the modulated wave generator. Umb, umc, three-phase modulation voltage uma, umb, umc are compared with the respective phase-shifting carriers, and the PWM driving signals of the corresponding IGBTs of the rectifier modules of each phase of the machine side are generated, the phase A is PWMmal~PWMman, and the phase B is PWMmbl~PWMmbn, Phase C is PWMmcl~PWMmcn. Reactive current reference imd* is the settable amount required by the system to adjust the power factor angle of the machine side rectification. The Park inverse transform generates a sinusoidal modulation signal, and the current loop can realize the artificial adjustment of the machine side rectified current sinusoidal and the machine side rectified power factor angle.
桨叶直接驱动中压鼠笼异步发电机转动， 当交-直-交型变流器的电机侧产生的基 波频率低于中压鼠笼异步发电机当前转速所对应的电频率时（即发电机的转差频率为 负）， 鼠笼异步发电机工作在发电状态， 通过控制发电机的转差和定子电压可以控制 发电机的输出功率；鼠笼异步发电机发出的交流电分别由各 H桥整流模块转换成为 H 桥整流模块各自的直流电； H桥整流模块各自的直流电通过各自的三相逆变模块转化 成为三相工频交流电施加在移相变压器相应的副边绕组上，从而通过移相变压器的铁 心耦合至移相变压器的原边三相绕组， 变压器的原边 A、 B、 C三相绕组分别与电网 的 、 B、 C三相连接， 实现向电网输送电能。 当因任何原因 （譬如风力过大） 导致 某个或某些功率单元的直流支撑电容的电压超过规定的阈值时，斩波制动模块中的全 控功率开关器件自动导通，通过制动电阻消耗过剩的能量，使直流支撑电容的电压被 限制在不超过规定的阈值。  The blade directly drives the medium voltage squirrel cage asynchronous generator to rotate, when the fundamental frequency generated by the motor side of the AC-DC-AC converter is lower than the electric frequency corresponding to the current speed of the medium voltage squirrel cage asynchronous generator (ie The slip frequency of the generator is negative), the squirrel cage asynchronous generator works in the power generation state, and the output power of the generator can be controlled by controlling the slip of the generator and the stator voltage; the alternating current generated by the squirrel cage asynchronous generator is respectively made by each H The bridge rectifier module is converted into the DC power of the H-bridge rectifier module; the respective DC power of the H-bridge rectifier module is converted into a three-phase power frequency AC power by the respective three-phase inverter module, and is applied to the corresponding secondary winding of the phase shifting transformer, thereby moving The core of the phase transformer is coupled to the primary three-phase winding of the phase shifting transformer. The three-phase windings of the primary side of the transformer are connected to the three-phase windings of the power grid, B and C, respectively, to realize the transmission of electrical energy to the power grid. When the voltage of the DC supporting capacitor of one or some power units exceeds a specified threshold for any reason (such as excessive wind), the fully controlled power switching device in the chopper braking module is automatically turned on, through the braking resistor Excessive energy is consumed so that the voltage of the DC supporting capacitor is limited to not exceed a prescribed threshold.
由于兆瓦级直驱式交-直-交型变流器采用 H桥串联技术和多副边绕组移相变压器 隔离技术，使风力发电***可以采用各种电压等级的中压甚至高压的鼠笼异步发电机 成为可能。 由于采用中压甚至高压的三相或多相鼠笼异步发电机， 以及与之配套的交 -直-交型变流器， 使实现更大功率的风力发电***成为可能； 由于交-直 -交型变流器 与风力发电机功率相当、斩波制动模块的采用、风力发电机与电网之间没有直接的耦 合关系， 使该风力发电***实现低电压穿越功能更为容易； 由于交 -直-交型变流器的 三相逆变模块与直流支撑电容结构构成了动态无功发生器主电路拓扑的关键要素，因 此该风力发电***还可兼作动态无功发生器， 可以对电网的无功进行实时、有效地补 偿。 Because the megawatt direct-drive AC-DC-AC converter adopts H-bridge series technology and multi-side winding phase shift transformer isolation technology, the wind power generation system can adopt medium voltage or even high pressure squirrel cage of various voltage levels. Asynchronous generator become possible. Thanks to medium-voltage or even high-voltage three-phase or multi-phase squirrel cage asynchronous generators, and the matching AC-DC-AC converters, it is possible to realize a more powerful wind power system; The AC-type converter has the same power as the wind turbine, the adoption of the chopper braking module, and the direct coupling between the wind turbine and the grid, making it easier for the wind power system to achieve low voltage ride-through function; The three-phase inverter module of the direct-interchange converter and the DC support capacitor structure constitute the key elements of the main circuit topology of the dynamic var generator, so the wind power generation system can also double as a dynamic var generator, which can be used for the grid. Reactive power is compensated in real time and effectively.

Claims

权 利 要 求 书 Claim
1 . 一种兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于， 包 括鼠笼异步发电机、 兆瓦级四象限交-直 -交变流器和移相变压器； 所述兆瓦级四象限 交-直-交变流器由三个变流链构成， 每个变流链由多个功率单元串联组成， 链首的功 率单元连接鼠笼异步发电机的一相定子绕组，三个链尾的功率单元连接在一起； 每个 变流链中各功率单元的输出端连接至移相变压器对应相的副边绕组，通过移相变压器 的铁心耦合至移相变压器的原边三相绕组，移相变压器的原边三相绕组分别与电网的 三相连接。 1 . A megawatt direct-drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system, which comprises a squirrel cage asynchronous generator, a MW four-quadrant AC-DC-AC converter and a shifting Phase transformer; the megawatt four-quadrant AC-DC-AC converter is composed of three converter chains, each of which is composed of a plurality of power units connected in series, and the power unit of the chain head is connected to the squirrel cage asynchronous generator One-phase stator winding, three chain tail power units are connected together; the output end of each power unit in each converter chain is connected to the secondary winding of the phase-shifting transformer corresponding phase, and is coupled to the shift through the core of the phase shifting transformer The primary side three-phase winding of the phase transformer, the primary side three-phase winding of the phase shifting transformer is respectively connected to the three-phase of the power grid.
2.根据权利要求 1所述的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于， 所述功率单元包括 H桥整流模块、 直流支撑电容、 斩波制动模块和三 相逆变模块； H桥整流模块的两个直流输出端与直流支撑电容的两极分别相连； 再连 接斩波制动模块和三相逆变模块的直流端，三相逆变模块的三相交流输出端连接三相 滤波电抗器；  2 . The megawatt-level direct drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system according to claim 1 , wherein the power unit comprises an H-bridge rectifier module, a DC support capacitor, and a chopper system. The moving module and the three-phase inverter module; the two DC output ends of the H-bridge rectifier module are respectively connected with the two poles of the DC supporting capacitor; and the DC terminal of the chopper braking module and the three-phase inverter module are connected, and the three-phase inverter module The three-phase AC output terminal is connected to the three-phase filter reactor;
所述 H桥整流模块的输入端用于连接鼠笼异步发电机的定子绕组或各功率单元 的串联连接； 所述三相滤波电抗器为各功率单元的输出端。  The input end of the H-bridge rectifier module is used to connect a stator winding of a squirrel-cage asynchronous generator or a series connection of each power unit; the three-phase filter reactor is an output end of each power unit.
3.根据权利要求 2所述的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于， 所述 H桥整流模块是由全控型功率开关器件组成双半桥结构， 每个半 桥上包含两个全控功率开关器件，每个半桥上两个全控功率开关器件的连接点作为 H 桥整流模块的输入端， 所述全控功率开关器件均并联续流二极管。  The megawatt-level direct-drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system according to claim 2, wherein the H-bridge rectifier module is composed of a fully-controlled power switching device. Bridge structure, each half bridge includes two fully-controlled power switching devices, and the connection point of two fully-controlled power switching devices on each half-bridge is used as an input end of the H-bridge rectifier module, and the full-control power switching devices are all connected in parallel Freewheeling diode.
4.根据权利要求 2所述的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于， 所述斩波制动模块由一个全控功率开关器件和一个制动电阻串联组成， 所述全控功率开关器件和制动电阻均并联续流二极管。  The megawatt-level direct drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system according to claim 2, wherein the chopper braking module comprises a fully-controlled power switching device and a system The dynamic resistors are formed in series, and the full-control power switching device and the braking resistor are connected in parallel with the freewheeling diode.
5.根据权利要求 2所述的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于，所述三相逆变模块由全控功率开关器件组成三半桥结构，每个半桥上包 含两个全控功率开关器件，每个半桥上两个全控功率开关器件的连接点作为三相逆变 模块的三个交流输出端之一， 所述全控功率开关器件均并联续流二极管。  The megawatt-level direct-drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system according to claim 2, wherein the three-phase inverter module is composed of a full-control power switching device and a three-half bridge Structure, each half bridge includes two fully-controlled power switching devices, and the connection point of two fully-controlled power switching devices on each half-bridge is one of three AC output terminals of the three-phase inverter module, the full control The power switching devices are all connected in parallel with a freewheeling diode.
6.根据权利要求 1所述的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于，所述链首的功率单元可通过滤波电抗器连接鼠笼异步发电机的一相定子 绕组。  6 . The megawatt-level direct drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system according to claim 1 , wherein the power unit of the chain head can be connected to the squirrel cage asynchronous power generation through a filter reactor. One phase stator winding of the machine.
7.根据权利要求 1所述的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于， 所述鼠笼异步发电机采用中压鼠笼异步发电机。  The megawatt-level direct-drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system according to claim 1, wherein the squirrel-cage asynchronous generator adopts a medium-voltage squirrel cage asynchronous generator.
8.根据权利要求 1所述的兆瓦级直驱型鼠笼异步发电机交-直 -交风力发电***， 其特征在于， 所述笼异步发电机具有多套三相定子绕组时， 则所述兆瓦级四象限交- 直-交变流器具有相应套数的变流链。  8 . The megawatt-level direct drive squirrel-cage asynchronous generator AC-DC-AC wind power generation system according to claim 1 , wherein when the cage asynchronous generator has multiple sets of three-phase stator windings, The megawatt four-quadrant cross-direct-cross current converter has a corresponding set of variable flow chains.
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