Wind driven generator and control method and device of power conversion circuit of wind driven generator

文档序号：1101167 发布日期：2020-09-25 浏览：13次中文

阅读说明：本技术 风力发电机及其功率转换电路的控制方法和装置 (Wind driven generator and control method and device of power conversion circuit of wind driven generator ) 是由张鲁华陈晓静刘嘉明葛昊祥方杭杭于 2020-06-16 设计创作，主要内容包括：本申请提供一种风力发电机及其功率转换电路的控制方法和装置。控制方法包括：获取直流母线的直流母线电压；若直流母线电压高于第一预设值,控制机侧变流器的部分的功率开关导通,以使电机的电枢电阻与直流母线连通,泄放直流母线的电能；若直流母线电压低于第二预设值,控制机侧变流器的部分的功率开关截止,以断开电机的电枢电阻与直流母线,结束泄放,第二预设值低于第一预设值。在直流母线电压升高时,将直流母线电压控制在电压承受范围内,保证电机的正常并网运行,从而保护电机、直流母线和风力发电机免受损坏。(The application provides a wind driven generator and a control method and device of a power conversion circuit of the wind driven generator. The control method comprises the following steps: acquiring the direct current bus voltage of a direct current bus; if the voltage of the direct current bus is higher than a first preset value, controlling a power switch of a part of the machine side converter to be conducted so as to enable an armature resistor of the motor to be communicated with the direct current bus and discharge the electric energy of the direct current bus; and if the voltage of the direct current bus is lower than a second preset value, controlling a part of power switches of the machine side converter to be cut off so as to disconnect the armature resistor of the motor and the direct current bus and finish the discharge, wherein the second preset value is lower than the first preset value. When the voltage of the direct current bus rises, the voltage of the direct current bus is controlled within a voltage bearing range, and normal grid-connected operation of the motor is guaranteed, so that the motor, the direct current bus and the wind driven generator are protected from being damaged.)

1. A control method for a power conversion circuit of a wind power generator, the wind power generator including a motor connected to the power conversion circuit, the power conversion circuit including a machine side converter connected to the motor and a dc bus connected to the machine side converter, the control method comprising:

acquiring the direct current bus voltage of the direct current bus;

if the voltage of the direct current bus is higher than a first preset value, controlling a power switch of a part of the machine side converter to be conducted so as to enable an armature resistor of the motor to be communicated with the direct current bus and discharge the electric energy of the direct current bus;

if the voltage of the direct current bus is lower than a second preset value, controlling the power switch of the part of the machine side converter to be cut off so as to disconnect the armature resistor of the motor and the direct current bus and finish the discharge;

the second preset value is lower than the first preset value.

2. The control method according to claim 1, wherein the motor includes star-connected three-phase armature resistors;

if the voltage of the direct current bus is higher than the first preset value, controlling the power switch of the part of the machine side converter to be conducted, and the method comprises the following steps:

and the power switch is used for controlling the conduction of the power switch which is connected with the first end of the direct current bus and the armature resistor of one phase, and the power switch which is connected with the second end of the direct current bus and the armature resistor of at least one phase of the other two phases.

3. The method of claim 2, wherein controlling the conduction of the power switch connecting the first end of the dc bus to the armature resistor of one of the phases and the power switch connecting the second end of the dc bus to the armature resistor of at least one of the other two phases comprises:

if the voltage of the direct current bus is higher than the first preset value, the power switch connected with the first end of the direct current bus and one of the phases of the armature resistors and the power switch connected with the second end of the direct current bus and the other phase of the armature resistors are controlled to be conducted, so that the two phases of the armature resistors are connected in series and then communicated with the direct current bus, and the electric energy of the direct current bus is discharged.

4. The method of claim 2, wherein controlling the conduction of the power switch connecting the first end of the dc bus to the armature resistor of one of the phases and the power switch connecting the second end of the dc bus to the armature resistor of at least one of the other two phases comprises:

if the voltage of the direct-current bus is higher than the first preset value, controlling a power switch connected with the first end of the direct-current bus and one of the phases of the armature resistors to be conducted with a power switch connected with the second end of the direct-current bus and the other two phases of the armature resistors, so that the other two phases of the armature resistors connected with the second end of the direct-current bus are connected in parallel and then connected in series with the one of the phases of the armature resistors connected with the first end of the direct-current bus, and are communicated with the direct-current bus to discharge the electric energy of the direct-current bus.

5. The control method of claim 4, wherein the first end of the DC bus is a positive end and the second end of the DC bus is a negative end;

the power switch which is connected with the first end of the direct current bus and part of the armature resistor and the power switch which is connected with the second end of the direct current bus and at least one other phase of the armature resistor are controlled to be conducted, and the method comprises the following steps:

if the voltage of the direct current bus is higher than the first preset value, controlling the power switch connected with the positive end of the direct current bus and one phase of the armature resistor to be conducted with the power switch connected with the negative end of the direct current bus and the other two phases of the armature resistors, so that the other two phases of the armature resistors connected with the negative end of the direct current bus are connected in parallel and then connected in series with the armature resistor connected with one phase of the positive end of the direct current bus, and are communicated with the direct current bus to discharge the electric energy of the direct current bus.

6. The control method of claim 4, wherein the first end of the DC bus is a negative end and the second end of the DC bus is a positive end;

if the voltage of the direct current bus is higher than the first preset value, controlling the power switch connected with the negative end of the direct current bus and one of the armature resistors to be conducted with the power switch connected with the positive end of the direct current bus and the other two-phase armature resistors, so that the other two-phase armature resistors connected with the positive end of the direct current bus are connected in parallel and then connected in series with the armature resistor connected with one of the phases of the negative end of the direct current bus, and are communicated with the direct current bus to discharge the electric energy of the direct current bus.

7. The control method according to any one of claims 1 to 6, characterized in that the wind generator further comprises a brake unit connected between the positive and negative terminals of the direct current bus, the brake unit comprising a brake resistor and a brake switch in series with the brake resistor; the control method comprises the following steps:

if the voltage of the direct-current bus is higher than the first preset value, controlling the brake switch to be conducted so as to enable the brake resistor to be communicated with the direct-current bus and discharge the electric energy of the direct-current bus;

if the voltage of the direct current bus is lower than the second preset value, controlling the brake switch to be cut off so as to disconnect the brake resistor and the direct current bus and finish the discharge;

the second preset value is lower than the first preset value.

8. A computer-readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements a method of controlling a power conversion circuit of a wind turbine according to any of claims 1 to 7.

9. A control arrangement of a power conversion circuit of a wind turbine generator, characterized by comprising one or more processors for implementing a control method of a power conversion circuit of a wind turbine generator according to any of claims 1 to 7.

10. A wind power generator, comprising:

a motor;

the power conversion circuit is connected with the motor and used for converting electric energy output by the motor, the power conversion circuit comprises a machine side converter, a direct current bus and a grid side converter, the machine side converter is electrically connected with the motor, the direct current bus is electrically connected with the machine side converter, and the grid side converter is electrically connected with the direct current bus; and

the control device of a power conversion circuit of a wind power generator as claimed in claim 9, said control device being electrically connected to said machine side converter.

Technical Field

The application relates to the field of wind power generation, in particular to a wind driven generator and a control method and device of a power conversion circuit of the wind driven generator.

Background

With the development of wind power generation technology, wind power generators are gradually developed into a parallel operation control mode of a current double-PWM (Pulse width modulation) back-to-back system. The system with the method has stable operation and high circuit reliability, and is effectively applied to the wind driven generator.

In the practical application process, when the wind driven generator is in a grid-connected state and meets the working conditions of sudden voltage drop of a power grid, high voltage recovery and the like, hardware of the wind driven generator is damaged or disconnected, and adverse effects are generated on the operation of the wind driven generator.

Disclosure of Invention

The application provides an improved wind driven generator and a control method and device of a power conversion circuit of the wind driven generator.

The embodiment of the application provides a control method of a power conversion circuit of a wind driven generator, wherein the wind driven generator comprises a motor connected with the power conversion circuit, the power conversion circuit comprises a machine side converter connected with the motor and a direct current bus connected with the machine side converter, and the control method comprises the following steps:

acquiring the direct current bus voltage of the direct current bus;

the second preset value is lower than the first preset value.

Optionally, the motor comprises three phases of armature resistors connected in a star shape;

Optionally, the controlling the conduction of the power switch connecting the first end of the dc bus and the armature resistor of one of the phases, and the power switch connecting the second end of the dc bus and the armature resistor of at least one of the other two phases includes:

Optionally, the first end of the dc bus is a positive end, and the second end of the dc bus is a negative end;

Optionally, the first end of the dc bus is a negative end, and the second end of the dc bus is a positive end;

Optionally, the wind power generator further includes a brake unit connected between the positive end and the negative end of the dc bus, where the brake unit includes a brake resistor and a brake switch connected in series with the brake resistor; the control method comprises the following steps:

the second preset value is lower than the first preset value.

The present embodiment provides a computer readable storage medium, on which a computer program is stored, wherein the program is executed by a processor to implement the control method of the power conversion circuit of the wind power generator according to any one of the above.

The embodiment of the present application provides a control device of a power conversion circuit of a wind power generator, wherein the control device includes one or more processors, and is used for implementing a control method of the power conversion circuit of the wind power generator as described in any one of the above.

The embodiment of the present application provides a wind power generator, wherein, include:

a motor;

and the control device of the power conversion circuit of the wind driven generator is electrically connected with the machine side converter.

According to the technical scheme provided by the embodiment of the application, the power switch of the part of the machine side converter is controlled to be conducted, so that the armature resistor of the motor is used as a discharge resistor to be communicated with the direct current bus, the electric energy of the direct current bus is discharged, when the voltage of the direct current bus is increased, the voltage of the direct current bus is controlled within a voltage bearing range, the normal grid-connected operation of the motor is ensured, and the motor, the direct current bus and the wind driven generator are protected from being damaged.

Drawings

FIG. 1 is a schematic diagram of a related art wind turbine;

FIG. 2 is a schematic view of another related art wind turbine;

FIG. 3 is a schematic structural view of a wind turbine of the present application;

FIG. 4 is a schematic electrical circuit diagram of the wind turbine shown in FIG. 3;

FIG. 5 is a partial electrical schematic view of an embodiment of the wind turbine shown in FIG. 4;

FIG. 6 is a flow chart of a method of controlling the power conversion circuit of the wind turbine shown in FIG. 5;

FIG. 7 is a flowchart of one embodiment of step S2 of a method of controlling the power conversion circuit of the wind turbine shown in FIG. 6;

FIG. 8 is a flowchart of one embodiment of step S20 of a method of controlling the power conversion circuit of the wind turbine shown in FIG. 7;

FIG. 9 is a waveform illustrating the bleed voltage of the DC bus and the bleed current of the armature resistor;

FIG. 10 is a flowchart of another embodiment of step S20 of a method of controlling the power conversion circuit of the wind turbine shown in FIG. 7;

FIG. 11 is a flowchart of one embodiment of a step S201 of a method of controlling the power conversion circuit of the wind turbine shown in FIG. 10;

FIG. 12 is a flowchart of another embodiment of the step S201 of the control method of the power conversion circuit of the wind turbine shown in FIG. 10;

FIG. 13 is a partial electrical schematic view of another embodiment of the wind turbine shown in FIG. 4;

FIG. 14 is a flow chart of a method of controlling the power conversion circuit of the wind turbine shown in FIG. 13;

FIG. 15 is a waveform diagram of the leakage voltage of the DC bus, the leakage current of the armature resistor, and the leakage current of the brake resistor;

FIG. 16 is a schematic diagram of an embodiment of a control device for a power conversion circuit of a wind turbine according to the present application;

FIG. 17 is a schematic view of an embodiment of a wind turbine of the present application.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus consistent with certain aspects of the present application, as detailed in the appended claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. The use of the terms "a" or "an" and the like in the description and in the claims of this application do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" includes two, and is equivalent to at least two. The word "comprising" or "comprises", and the like, means that the element or item listed as preceding "comprising" or "includes" covers the element or item listed as following "comprising" or "includes" and its equivalents, and does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

Fig. 1 is a schematic view of a wind turbine 100 in the related art. As shown in fig. 1, the wind turbine 100 includes a motor 101, a machine-side converter 102, a dc bus 103, and a grid-side converter 104, the wind turbine 100 is electrically connected to a grid 105, the machine-side converter 102 is electrically connected to the motor 101, the grid-side converter 104 is electrically connected to the grid 105, and the dc bus 103 is connected between the machine-side converter 102 and the grid-side converter 104. The machine-side converter 102 and the grid-side converter 104 are coupled via a dc bus 103.

In the practical application process, when the wind turbine 100 is in a grid-connected state, and when the voltage of the power grid 105 suddenly drops or the high voltage recovers, and other working conditions are met, the active power transmitted to the direct current bus 103 side by the machine side converter 102 is greater than the active power output to the power grid 105 by the grid side converter 104, so that the voltage of the direct current bus 103 is increased, the hardware of the wind turbine 100 is damaged or disconnected, and the operation of the motor 101 is adversely affected.

Fig. 2 is a schematic view of another related art wind power generator 200. The related art shown in fig. 2 is similar to the related art shown in fig. 1, and a bleed device 201 is added to the wind turbine generator 200 shown in fig. 2, and is connected between a machine-side converter 204 and a grid-side converter 205, and is connected in parallel with a dc bus 206. The bleeder device 201 includes a bleeder resistor 202 and a bleeder switch 203 connected to the bleeder resistor 202. In view of the above problem, in the related art shown in fig. 2, the electric power of the dc bus 206 is discharged by adding the discharging device 201. When the voltage of the direct current bus 206 rises to or exceeds a first preset value of the direct current bus 206, the bleeder switch 203 is controlled to be turned on so that the bleeder resistor 202 is connected to be communicated with the direct current bus to bleed off the electric energy sharply increased on the direct current bus, and when the voltage of the direct current bus falls to or is lower than a second preset value of the direct current bus, the bleeder switch 203 is controlled to be turned off so that the bleeder resistor 202 is switched off, so that the voltage of the direct current bus is controlled within a voltage bearing range.

In practical application, for the MW-class wind driven generator, the electric energy to be discharged from the direct current bus during the fault reaches MJ class. In order to ensure that the electric energy of the direct current bus can be safely released in a short time, a high-power bleeder resistor 202 is required to be configured. For example, two bleed resistors 202 of volume up to 500mm x 450mm x 100mm need to be used for a 2.5MW full power wind generator. The bleeder resistor 202 results in a larger size of the bleeder device 201, taking up more space in the cabinet. When the discharging resistor 202 discharges, it will generate more heat, so that there is a certain fire hazard, and in order to ensure the normal operation of the discharging resistor 202 and the safety of other devices in the cabinet, a special heat dissipation device needs to be provided, for example, a heat dissipation fan needs to be additionally installed or a corresponding heat dissipation water path needs to be added, thereby increasing the cost of the wind turbine generator.

The embodiment of the application provides an improved wind driven generator and a control method and device of a power conversion circuit of the wind driven generator.

Fig. 3 is a schematic structural diagram of a wind turbine 300 according to the present application. As shown in FIG. 3, wind turbine 300 includes a tower 302 extending from a support surface 301, a nacelle 303 mounted on tower 302, and a rotor 304 assembled to nacelle 303. The rotor 304 includes a rotatable hub 3040 and at least one rotor blade 3041, the rotor blade 3041 being connected to the hub 3040 and extending outwardly from the hub 3040. In the embodiment illustrated in FIG. 3, the rotor 304 includes three rotor blades 3041. In some other embodiments, the rotor 304 may include more or fewer rotor blades. A plurality of rotor blades 3041 may be spaced about the hub 3040 to facilitate rotating the rotor 304 to enable wind energy to be converted into usable mechanical energy, and subsequently, electrical energy.

In some embodiments, an electric motor (not shown) is disposed within nacelle 303, and the electric motor (not shown) may be connected to rotor 304 for generating electrical power from the mechanical energy generated by rotor 304. In some embodiments, a control device (not shown) is also disposed within nacelle 20, and the control device (not shown) is communicatively coupled to electrical components of wind turbine 300 in order to control the operation of such components. In some embodiments, a control device (not shown) may also be disposed within any other component of the wind turbine 300, or at a location external to the wind turbine 300. In some embodiments, the control device (not shown) may comprise a computer or other processing unit. In some other embodiments, a control device (not shown) may include suitable computer readable instructions that, when executed, configure the control device (not shown) to perform various functions, such as receiving, transmitting, and/or executing control signals for the wind turbine 300. In some embodiments, a control device (not shown) may be configured to control various operating modes (e.g., start-up or shut-down sequences) of wind turbine 300 and/or to control various components of wind turbine 300.

Fig. 4 is a schematic circuit diagram of the wind power generator 300 shown in fig. 3. As shown in fig. 4, the wind power generator 300 includes a motor 305 and a power conversion circuit 306 connected to the motor 305. The motor 305 may comprise an asynchronous motor or a synchronous motor. In the present embodiment, motor 305 is a three-phase motor including three-phase windings 311, 312, and 313. The three-phase windings 311, 312 and 313 are star-connected, spatially separated by 120 electrical degrees. In some embodiments, the three phase windings 311, 312, and 313 are delta connected. In other embodiments, the motor 305 may be a multi-phase motor, such as a six-phase motor, or the like.

The power conversion circuit 306 may receive an electrical signal output from the motor 305, convert the electrical signal, and output the converted electrical signal. The power conversion circuit 306 can convert the ac signal into a dc signal, and then convert the dc signal into ac power for power frequency output. In the present embodiment, the power conversion circuit 306 is connected to the three-phase windings 311, 312 and 313, and is configured to receive the electrical signals output by the three-phase windings 311, 312 and 313, convert the electrical signals, and output the converted electrical signals.

In some embodiments, wind turbine 300 includes a control device 307, and control device 307 is coupled to power conversion circuitry 306 for controlling power conversion circuitry 306 to convert electrical signals output by motor 305.

In some embodiments, wind generator 300 includes a transformer 308 coupled to power conversion circuitry 306, transformer 308 being electrically coupled to a power grid 309. The converted electrical signal output by the power conversion circuit 306 may be boosted by a transformer 308 and transmitted to a power grid 309. The transformer 308 may comprise a three-winding transformer coupled to the power conversion circuit 306. In some embodiments, the voltage level of the three-winding transformer is 66kV/690V/690V, and the grid level of the grid 309 is 66 kV.

In the embodiment shown in fig. 4, the power conversion circuit 306 comprises a machine side converter 314 and a grid side converter 315 and a dc bus 316 connected between the machine side converter 314 and the grid side converter 315. Machine-side converter 314 is connected to motor 305, grid-side converter 315 is connected to transformer 308, and machine-side converter 314 is connected to grid-side converter 315. In some embodiments, machine side converter 314 comprises a rectifier and grid side converter 315 comprises an inverter. The electric signal output by the motor 305 is an ac electric signal, the machine-side converter 314 is configured to convert the electric signal output by the motor 305 into a dc electric signal, and the grid-side converter 315 is configured to convert the dc electric signal into a converted output electric signal and output the converted output electric signal to the transformer 308. Here, the output electric signal is converted into an alternating current electric signal having a frequency different from that of the electric signal. The electric signal is a low-frequency alternating current signal, and is converted into a power-frequency alternating current signal meeting the requirements of a power grid.

The control device 307 may comprise a machine-side control device 317 and a grid-side control device 318, the machine-side control device 317 being connected to the machine-side converter 314 for controlling the machine-side converter 314 to convert the electrical signal output by the motor 305 into a dc electrical signal. The grid-side control device 318 is connected to the grid-side converter 315, and is configured to control the grid-side converter 315 to convert the dc signal into a converted output electrical signal. Here, the machine-side control device 317 may control the voltage and/or power of the converted direct-current electric signal, and the grid-side control device 318 may control the voltage and/or power of the converted output electric signal.

The machine-side control device 317 and the network-side control device 318 may include any suitable Programmable Circuit or device, such as a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), a Programmable Logic Controller (PLC), an Application Specific Integrated Circuit (ASIC), and the like. The machine side control device 317 and the network side control device 318 can be controlled by a combination of hardware and software.

FIG. 5 is a partial electrical schematic view of an embodiment of the wind turbine 300 shown in FIG. 4. In the embodiment shown in fig. 5, the motor 305 includes star-connected three-phase armature resistors including a first armature resistor 320, a second armature resistor 321, and a third armature resistor 322. In some embodiments, the first armature resistor 320, the second armature resistor 321, and the third armature resistor 322 may be connected in other manners, such as a delta connection. In some embodiments, the resistance of the three-phase armature resistors may be the dc resistance of the three-phase windings of the motor 305 themselves. The direct current resistance value can be said to be the direct current resistance of the three-phase winding wire, is the direct current parameter of the three-phase winding, and can be measured by a universal meter.

In the embodiment shown in fig. 5, the machine side converter 314 comprises a first power switch 323, a second power switch 324, a third power switch 325, a fourth power switch 326, a fifth power switch 327 and a sixth power switch 328, the first armature resistor 320 is connected to the positive terminal 3160 of the dc bus 316 through the first power switch 323 and to the negative terminal 3161 of the dc bus 316 through the second power switch 324, the second armature resistor 321 is connected to the positive terminal 3160 of the dc bus 316 through the third power switch 325 and to the negative terminal 3161 of the dc bus 316 through the fourth power switch 326, and the third armature resistor 322 is connected to the positive terminal 3160 of the dc bus 316 through the fifth power switch 327 and to the negative terminal 3161 of the dc bus 316 through the sixth power switch 328. In some embodiments, the first power switch 323, the second power switch 324, the third power switch 325, the fourth power switch 326, the fifth power switch 327, and the sixth power switch 328 are all IGBT (Insulated gate bipolar Transistor) switches, which can be turned on and off in a very short time, and have high sensitivity and fast switching speed. In other embodiments, other power switches may be used for the first power switch 323, the second power switch 324, the third power switch 325, the fourth power switch 326, the fifth power switch 327, and the sixth power switch 328. And are not limited in this application.

In the embodiment shown in fig. 5, the collector of the first power switch 323 is connected to the positive terminal 3160 of the dc bus 316 and the emitter of the first power switch 323 is connected to the first armature resistor 320. The collector of the second power switch 324 is connected to the first armature resistor 320, and the emitter of the second power switch 324 is connected to the negative terminal 3161 of the dc bus 316. The collector of the third power switch 325 is connected to the positive terminal 3160 of the dc bus 316 and the emitter of the third power switch 325 is connected to the second armature resistor 321. The collector of the fourth power switch 326 is connected to the second armature resistor 321, and the emitter of the fourth power switch 326 is connected to the negative terminal 3161 of the dc bus 316. The collector of the fifth power switch 327 is connected to the positive terminal 3160 of the dc bus 316 and the emitter of the fifth power switch 327 is connected to the third armature resistor 322. The collector of the sixth power switch 328 is connected to the third armature resistor 322 and the emitter of the sixth power switch 328 is connected to the negative terminal 3161 of the dc bus 316.

In some embodiments, gates of the first power switch 323, the second power switch 324, the third power switch 325, the fourth power switch 326, the fifth power switch 327, and the sixth power switch 328 as control terminals of the switches may be connected to different control ports of the machine side control device 317, and the different control ports independently control the power switches. In some embodiments, different control ports may control corresponding power switches synchronously. In some embodiments, the working principle and the connection manner of the machine-side control device 317 disposed in the power conversion circuit 306 may refer to the working manner and the connection manner of the machine-side control device 317 illustrated in fig. 4, which are not described herein again.

In the embodiment shown in fig. 5, when the dc bus voltage of the dc bus 316 is higher than the first preset value, it needs to be adjusted by using the control method of the power conversion circuit 306 of the wind turbine 300, so that the wind turbine 300 is in a grid-connected state, and the active power transmitted by the machine-side converter 314 to the dc bus 316 side is balanced with the active power output by the grid-side converter 315 to the grid 309.

Fig. 6 is a flowchart of a control method of the power conversion circuit 306 of the wind turbine 300 shown in fig. 5. As shown in FIG. 6, the control method of the power conversion circuit 401 of the wind turbine 300 includes steps S1-S3.

In step S1, a dc bus voltage of the dc bus is acquired.

In some embodiments, a dc bus voltage detection circuit of the dc bus 316 is disposed inside the machine side control device 317, and the dc bus voltage of the dc bus 316 can be obtained. In some embodiments, the machine side control device 317 may be a processor, and the dc bus voltage detection circuit may be integrated in the processor, so as to simplify the circuit structure and save the cost. In some embodiments, the dc bus voltage detection circuit may detect the dc bus voltage of the dc bus 316 by a combination of hardware and software.

In step S2, if the dc bus voltage is higher than the first preset value, the power switch of the part controlling the machine-side converter 314 is turned on, so that the armature resistance of the motor 305 is communicated with the dc bus 316, and the electric power of the dc bus 316 is discharged.

In some embodiments, the dc bus voltage of the dc bus 316 normally operates around 1100V. In some embodiments, the first preset value may be 1180V. In other embodiments, the first preset value may be set to other values.

In some embodiments, when the dc bus voltage of dc bus 316 is higher than 1180V, machine side control device 317 controls machine side converter 314 to stop modulating, and then controls the power switch of the portion of machine side converter 314 to conduct, so that the armature resistance of motor 305 communicates with dc bus 316, and the electric energy of dc bus 316 is discharged. In some embodiments, the machine-side control device 317 controls the power switches of the portion of the machine-side converter 314 to be turned on and the other power switches to be turned off, so that the electric energy of the dc bus 316 is stably discharged. The Modulation here means that the machine-side converter 314 is turned on or off by controlling a power switch according to a logic set by a program by using a Modulation method such as Space Vector Pulse Width Modulation (SVPWM) or Sinusoidal Pulse Width Modulation (SPWM). The bleeding here refers to the power switch of the conducting part establishing a bleeding path of the dc bus 316 and the motor resistance. In some embodiments, the grid-side control device 318 may still control the grid-side converter 315 to maintain the modulation state while discharging the power of the dc bus 316, firstly to ensure that the electric machine 305 does not operate off the grid, and secondly to provide a power transmission path for the power transmission of the dc bus 316 to transmit the power of the dc bus 316 to the grid-side converter 315.

In the embodiment shown in fig. 6, when the wind turbine 100 is in a grid-connected state, and when the voltage of the power grid 105 suddenly drops or the high voltage recovers, the active power transmitted by the machine-side converter 102 to the side of the dc bus 103 is converted into the kinetic energy of the rotor of the motor 305, the armature resistance of the motor 305 is used as a bleed-off resistance to communicate with the dc bus 316, so as to bleed off the electric energy of the dc bus 316, the dc bus voltage of the dc bus 316 is controlled within a voltage bearing range, and the normal grid-connected operation of the motor 305 is ensured, thereby protecting the motor 305, the dc bus 316, and the wind turbine 300 from being damaged. Compared with the related art shown in fig. 2, the bleed device is not required to be added, the space in the wind turbine 300 can be saved, and the heat dissipation device is not required to be added, so that the cost of the wind turbine 300 is reduced.

In step S3, if the dc bus voltage is lower than a second preset value, which is lower than the first preset value, the power switch of the part of the machine-side converter 314 is controlled to be turned off to disconnect the armature resistance of the motor 305 from the dc bus 316, and the bleeding is ended.

In some embodiments, the dc bus voltage of the dc bus 316 normally operates around 1100V. In some embodiments, the second preset value may be 1120V. In other embodiments, the second preset value may be set to other values. In some embodiments, when the dc bus voltage of the dc bus 316 is lower than 1120V, the machine side control device 317 controls the power switch of the part of the machine side converter 314 to be turned off to disconnect the armature resistance of the motor 305 from the dc bus 316, to end the bleeding, and then controls the machine side converter 314 to start modulation.

In some embodiments, the dc bus voltage between the first preset value and the second preset value may be a bleed voltage of the armature resistor of the motor 305 communicating with the dc bus 316, and during the process of decreasing the dc bus voltage from the first preset value to the second preset value, the wind turbine 300 can run without interruption, supporting the recovery of the power grid 309 until the power grid 309 recovers to normal. When the dc bus voltage of the dc bus 316 is controlled within the voltage tolerance range, the normal grid-connected operation of the motor 305 is ensured, thereby protecting the motor 305, the dc bus 316, and the wind turbine 300 from damage. Compared with the related art shown in fig. 2, the space in the wind turbine 300 can be saved without adding a relief device, and a heat dissipation device is not required, thereby reducing the cost of the wind turbine 300.

In some embodiments, the operating voltage at which the dc bus voltage of the dc bus 316 operates normally is not limited in this application. In some embodiments, the safe voltage range value of the dc bus voltage of the dc bus 316 and the upper limit value or the lower limit value of the safe voltage range value may be set to other values, which are not limited in this application.

FIG. 7 is a flowchart of an embodiment of step S2 of the method for controlling the power conversion circuit 306 of the wind turbine 300 shown in FIG. 6. As shown in fig. 7, step S2 of the control method of the power conversion circuit 306 of the wind power generator 300 includes step S20. Wherein the content of the first and second substances,

step S20, controlling the power switch connecting the first end of the dc bus 316 and one of the phase pivot resistors and the power switch connecting the second end of the dc bus 316 and at least one of the other two phases to be turned on. The first end of the dc bus 316 is in resistance communication with one of the phase armature resistors through the corresponding conducting power switch, and the second end of the dc bus 316 is in resistance communication with at least one of the other two phases through the corresponding conducting power switch, so that the electric energy of the dc bus 316 is transmitted to the armature resistor through the conducting power switch to be discharged. In some embodiments, the first end of the dc bus 316 may be the positive terminal 3160. In some embodiments, the second end of the dc bus 316 may be the negative end 3161. In some embodiments, when the dc bus voltage of the dc bus 316 is higher than the first preset value, and the machine side control device 317 controls the machine side converter 314 to stop modulation, the motor 305 does not generate useful work, and at this time, the active power transmitted to the dc bus 103 side by the machine side converter 102 is converted into the kinetic energy of the rotor of the motor 305 to be consumed, the three-phase armature resistor of the motor 305 can be used as a bleed resistor to bleed off the electric energy accumulated on the dc bus 316, and when there is a bleed current, the rotation speed of the motor 305 is increased, but the function of the motor 305 itself is not affected.

In some embodiments, the control of the power switch is independent of the resistance of the armature resistor, which affects the rate of bleeding of the dc bus voltage of the dc bus 316, and thus the time of bleeding of the dc bus voltage of the dc bus 316. In some embodiments, the smaller the resistance value of the leakage resistor formed by the plurality of armature resistors, the larger the leakage current, the larger the active power generated, the faster the leakage speed, and the shorter the leakage time.

FIG. 8 is a flowchart of an embodiment of step S20 of the method for controlling the power conversion circuit 306 of the wind turbine 300 shown in FIG. 7. As shown in fig. 8, step S20 of the control method of the power conversion circuit 306 of the wind power generator 300 includes step S200. Wherein the content of the first and second substances,

step S200, if the voltage of the dc bus is higher than the first preset value, controlling the power switch connected to the first end of the dc bus 316 and one of the phase of armature resistors, and the power switch connected to the second end of the dc bus 316 and the other phase of armature resistor to be turned on, so that the two phase of armature resistors are connected in series and then communicated with the dc bus 316, and discharging the electric energy of the dc bus 316. At this time, the other power switches of the controller-side converter 314 are turned off.

In some embodiments, the dc bus voltage of the dc bus 316 normally operates around 1100V. In some embodiments, the first preset value may be 1180V and the second preset value may be 1120V. In other embodiments, the first preset value and the second preset value may be set to other values. In some embodiments, the first end of the dc bus 316 may be the positive terminal 3160 and the second end of the dc bus 316 may be the negative terminal 3161. In conjunction with the embodiments shown in fig. 5 and 8, the first end of the dc bus 316 is the positive terminal 3160 and the second end of the dc bus 316 is the negative terminal 3161.

In some embodiments, when the voltage of the dc bus is higher than the first preset value, the machine-side control device 317 controls the machine-side converter 314 to stop modulating, and may control the first power switch 323 and the fourth power switch 326 to be turned on, so that the first armature resistor 320 and the second armature resistor 321 are connected in series and then communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the second power switch 324, the third power switch 325, the fifth power switch 327 and the sixth power switch 328 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the first power switch 323 and the fourth power switch 326 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine-side control device 317 controls the machine-side converter 314 to stop modulating, and may control the third power switch 325 and the second power switch 324 to conduct, so that the second armature resistor 321 is connected in series with the first armature resistor 320 and then is communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the first power switch 323, the fourth power switch 326, the fifth power switch 327 and the sixth power switch 328 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the second power switch 324 and the third power switch 325 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine-side control device 317 controls the machine-side converter 314 to stop modulating, and may control the first power switch 323 and the sixth power switch 328 to conduct, so that the first armature resistor 320 and the third armature resistor 322 are connected in series and then communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the second power switch 324, the third power switch 325, the fourth power switch 326 and the fifth power switch 327 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the first power switch 323 and the sixth power switch 328 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the third armature resistor 322 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine-side control device 317 controls the machine-side converter 314 to stop modulating, and may control the fifth power switch 327 and the second power switch 324 to be turned on, so that the third armature resistor 322 is connected in series with the first armature resistor 320 and then is connected to the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the first power switch 323, the third power switch 325, the fourth power switch 326 and the sixth power switch 328 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the second power switch 324 and the fifth power switch 327 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the third armature resistor 322 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine-side control device 317 controls the machine-side converter 314 to stop modulating, and may control the third power switch 325 and the sixth power switch 328 to conduct, so that the second armature resistor 321 is connected in series with the third armature resistor 322 and then is communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the first power switch 323, the second power switch 324, the fourth power switch 326 and the fifth power switch 327 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the third power switch 325 and the sixth power switch 328 of the machine side converter 314 to be turned off to disconnect the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine-side control device 317 controls the machine-side converter 314 to stop modulating, and may control the fifth power switch 327 and the fourth power switch 326 to be turned on, so that the third armature resistor 322 and the second armature resistor 321 are connected in series and then communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the first power switch 323, the second power switch 324, the third power switch 325 and the sixth power switch 328 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the fourth power switch 326 and the fifth power switch 327 of the machine side converter 314 to be turned off to disconnect the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and the bleeding is ended.

In the embodiment shown in fig. 5 and 8, when the resistance values of the first armature resistor 320, the second armature resistor 321, and the third armature resistor 322 are R, the resistance value of the bleed circuit formed by connecting two armature resistors in series and communicated with the dc bus 316 is 2R, the armature resistor of the motor 305 is used as a bleed resistor and communicated with the dc bus 316 to bleed the electric energy of the dc bus 316, so as to control the dc bus voltage of the dc bus 316 within a voltage bearing range, thereby ensuring the normal grid-connected operation of the motor 305, and thus protecting the motor 305, the dc bus 316, and the wind turbine 300 from being damaged. Compared with the related art shown in fig. 2, the space in the wind turbine 300 can be saved without adding a relief device, and a heat dissipation device is not required, thereby reducing the cost of the wind turbine 300.

Fig. 9 is a waveform diagram of the bleed voltage of the dc bus 316 and the bleed current of the armature resistor. Taking a wind power generator 300 with a full power of 3000kW as an example, when the wind power generator 300 operates at a rated power, the active power of the machine-side converter 314 is 3000kW, and when the active power transmitted by the machine-side converter 314 is greater than the active power transmitted by the grid-side converter 315, and the voltage of the dc bus is increased to the first preset value 1180V, any of the embodiments shown in fig. 8 is adopted, the armature resistor of the motor 305 is used as a bleed resistor to be communicated with the dc bus 316, the voltage of the dc bus is pulled down to the second preset value 1120V, so as to bleed off the electric energy of the dc bus 316, the voltage of the dc bus 316 can be controlled within a voltage bearing range, thereby ensuring the normal grid-connected operation of the motor 305, and protecting the motor 305 and the wind power generator 300 from being damaged. In fig. 9, a waveform 700 is a waveform diagram of the bleed-off voltage of the dc bus 316, an abscissa is time, an ordinate is voltage, a waveform 701 is a waveform diagram of the bleed-off current of the armature resistor, an abscissa is time, an ordinate is current, and as shown in fig. 9, a peak value of the bleed-off current of the bleed-off resistor is about 2500A. In some embodiments, when the dc bus 316 is bled off at a voltage higher than the normal operating voltage, the conversion of the grid-side converter 315 is operating normally and is not affected. In some embodiments, the peak value of the bleed current of the bleed resistor is measured by an oscilloscope.

Fig. 10 is a flowchart of another embodiment of step S20 of the control method of the power conversion circuit 306 of the wind turbine 300 shown in fig. 7. As shown in fig. 10, step S20 of the control method of the power conversion circuit 306 of the wind power generator 300 includes step S201. Wherein the content of the first and second substances,

step S201, if the voltage of the dc bus is higher than the first preset value, controlling the power switch connected to the first end of the dc bus 316 and one of the phase armature resistors and the power switch connected to the second end of the dc bus 316 and the other two-phase armature resistors to be turned on, so that the other two-phase armature resistors connected to the second end of the dc bus 316 are connected in parallel and then connected in series with the one of the phase armature resistors connected to the first end of the dc bus 316, and are communicated with the dc bus 316, thereby discharging the electric energy of the dc bus 316. At this time, the other power switches of the controller-side converter 314 are turned off.

In some embodiments, the dc bus voltage of the dc bus 316 normally operates around 1100V. In some embodiments, the first preset value may be 1180V and the second preset value may be 1120V. In other embodiments, the first preset value and the second preset value can be set to other values, and the second preset value is lower than the first preset value. In some embodiments, the first end of the dc bus 316 may be the positive terminal 3160 and the second end of the dc bus 316 may be the negative terminal 3161. In other embodiments, the first end of the dc bus 316 may be the negative terminal 3161 and the second end of the dc bus 316 may be the positive terminal 3160.

Fig. 11 is a flowchart of an embodiment of step S201 of the control method of the power conversion circuit 306 of the wind turbine 300 shown in fig. 10. As shown in fig. 11, step S201 of the control method of the power conversion circuit 306 of the wind power generator 300 includes step S2010.

Step S2010, if the voltage of the dc bus is higher than the first preset value, controlling the power switch connecting the positive terminal 3160 of the dc bus 316 and one of the phase armature resistors, and the power switch connecting the negative terminal 3161 of the dc bus 316 and the other two-phase armature resistors to be turned on, so that the other two-phase armature resistors connecting the negative terminal 3161 of the dc bus 316 are connected in parallel and then connected in series with the one of the phase armature resistors connecting the positive terminal 3160 of the dc bus 316, and are communicated with the dc bus 316, thereby discharging the electric energy of the dc bus 316. At this time, the other power switches of the controller-side converter 314 are turned off.

In conjunction with the embodiments shown in fig. 5 and 11, the first end of the dc bus 316 is the positive terminal 3160 and the second end of the dc bus 316 is the negative terminal 3161.

In some embodiments, when the voltage of the dc bus is higher than the first preset value, the machine side control device 317 controls the machine side converter 314 to stop modulating, and may control the first power switch 323, the fourth power switch 326 and the sixth power switch 328 to conduct, so that the second armature resistor 321 is connected in parallel with the third armature resistor 322, then connected in series with the first armature resistor 320, and communicated with the dc bus 316, to discharge the power of the dc bus 316. At this time, the second power switch 324, the third power switch 325 and the fifth power switch 327 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the first power switch 323, the fourth power switch 326 and the sixth power switch 328 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine side control device 317 controls the machine side converter 314 to stop modulating, and may control the third power switch 325, the second power switch 324, and the sixth power switch 328 to conduct, so that the first armature resistor 320 is connected in parallel with the third armature resistor 322, then connected in series with the second armature resistor 321, and communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the first power switch 323, the fourth power switch 326 and the fifth power switch 327 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the second power switch 324, the third power switch 325 and the sixth power switch 328 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine-side control device 317 controls the machine-side converter 314 to stop modulating, and may control the fifth power switch 327, the second power switch 324, and the fourth power switch 326 to be turned on, so that the first armature resistor 320 is connected in parallel with the second armature resistor 321, then connected in series with the third armature resistor 322, and communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the first power switch 323, the third power switch 325 and the sixth power switch 328 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the second power switch 324, the fourth power switch 326 and the fifth power switch 327 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and ending the bleeding.

In the embodiment shown in fig. 5 and 11, when the resistance values of the first armature resistor 320, the second armature resistor 321, and the third armature resistor 322 are R, the resistance value of the armature resistor connected to the dc bus 316 is 1.5R. The embodiment shown in fig. 8 has a faster bleed rate and a shorter bleed time than the embodiment shown in fig. 11. The embodiment shown in fig. 11 has a smaller resistance value of the armature resistor communicating with the dc bus 316 than the embodiment shown in fig. 8. In any of the embodiments shown in fig. 11, the two-phase armature resistors of the motor 305 are connected in parallel and then connected in series with the other one-phase armature resistors as the bleed-off resistor to communicate with the dc bus 316, so as to bleed off the electric energy of the dc bus 316, and the dc bus voltage of the dc bus 316 can be controlled within a voltage bearing range, thereby ensuring the normal grid-connected operation of the motor 305, and protecting the motor 305, the dc bus 316, and the wind turbine 300 from being damaged. Compared with the related art described in fig. 2, the space in the wind turbine 300 can be saved without adding a braking device, and a heat dissipation device is not required, thereby reducing the cost of the wind turbine 300.

Fig. 12 is a flowchart of another embodiment of the step S201 of the control method of the power conversion circuit of the wind turbine shown in fig. 10. As shown in fig. 12, step S201 of the control method of the power conversion circuit 306 of the wind turbine 300 includes step S2011.

Step S2011, if the voltage of the dc bus is higher than the first preset value, the power switch connected to the negative terminal 3161 of the dc bus 316 and one of the phase armature resistors is controlled to be turned on, and the power switch connected to the positive terminal 3160 of the dc bus 316 and the other two-phase armature resistors is controlled to be turned on, so that the other two-phase armature resistors connected to the positive terminal 3160 of the dc bus 316 are connected in parallel and then connected in series to one of the phase armature resistors connected to the negative terminal 3161 of the dc bus 316, and then connected to the dc bus 316, thereby discharging the electric energy of the dc bus 316. At this time, the other power switches of the controller-side converter 314 are turned off.

In the embodiment shown in fig. 5 and 12, the first end of the dc bus 316 is the negative terminal 3161, and the second end of the dc bus 316 is the positive terminal 3160.

In some embodiments, when the voltage of the dc bus is higher than the first preset value, the machine side control device 317 controls the machine side converter 314 to stop modulating, and may control the first power switch 323, the third power switch 325 and the sixth power switch 328 to conduct, so that the first armature resistor 320 is connected in parallel with the second armature resistor 321, then connected in series with the third armature resistor 322, and communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the second power switch 324, the fourth power switch 326 and the fifth power switch 327 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the first power switch 323, the third power switch 325 and the sixth power switch 328 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and the bleeding is ended.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine side control device 317 controls the machine side converter 314 to stop modulating, and may control the first power switch 323, the fifth power switch 327 and the fourth power switch 326 to be turned on, so that the first armature resistor 320 is connected in parallel with the third armature resistor 322, then connected in series with the second armature resistor 321, and communicated with the dc bus 316, thereby discharging the power of the dc bus 316. At this time, the second power switch 324, the third power switch 325 and the sixth power switch 328 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the first power switch 323, the fourth power switch 326 and the fifth power switch 327 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and thus ending the bleeding.

In other embodiments, when the voltage of the dc bus is higher than the first preset value, the machine side control device 317 controls the machine side converter 314 to stop modulation, and may control the third power switch 325 and the fifth power switch 327 to be conducted with the first power switch 4013, and the second armature resistor 321 and the third armature resistor 322 are connected in parallel, then connected in series with the first armature resistor 320, and connected with the dc bus 316, so as to discharge the power of the dc bus 316. At this time, the second power switch 324, the fourth power switch 326 and the sixth power switch 328 are controlled to be turned off. In some embodiments, when the dc bus voltage is lower than the second preset value, the machine side control device 317 controls the first power switch 323, the third power switch 325 and the fifth power switch 327 of the machine side converter 314 to be turned off to disconnect the first armature resistor 320, the second armature resistor 321, the third armature resistor 322 and the dc bus 316, and ending the bleeding.

In the embodiment shown in fig. 5 and 12, when the resistance values of the first armature resistor 320, the second armature resistor 321, and the third armature resistor 322 are R, the resistance value of the armature resistor connected to the dc bus 316 is 1.5R. The embodiment shown in fig. 8 has a faster bleed rate and a shorter bleed time than the embodiment shown in fig. 12. The embodiment shown in fig. 12 has a smaller resistance value of the armature resistor communicating with the dc bus 316 than the embodiment shown in fig. 8. The embodiment shown in fig. 12 is the same as the embodiment shown in fig. 11 in resistance value of the armature resistor communicating with the dc bus 316, and the bleeding rate and the bleeding time are the same. In any of the embodiments shown in fig. 12, the two-phase armature resistors of the motor 305 are connected in parallel and then connected in series with the other one-phase armature resistors as the bleed-off resistor to communicate with the dc bus 316, so as to bleed off the electric energy of the dc bus 316, and the dc bus voltage of the dc bus 316 can be controlled within a voltage bearing range, thereby ensuring the normal grid-connected operation of the motor 305, and protecting the motor 305, the dc bus 316, and the wind turbine 300 from being damaged. And compared with the related art shown in fig. 2, it is not necessary to add a braking device, the space in the wind power generator 300 can be saved, and it is not necessary to add a heat sink, thereby reducing the cost of the wind power generator 300.

FIG. 13 is a partial electrical schematic view of another embodiment of the wind turbine 400 of the present application shown in FIG. 4. Wind turbine 400 shown in FIG. 13 is similar to wind turbine 300 shown in FIG. 5. In the embodiment shown in fig. 13, a wind turbine 400 is added with a braking device 401, wherein the braking device 401 comprises a braking resistor 402 and a braking switch 403 in series with the braking resistor 402. One end of the brake 401 is connected to the positive terminal 4110 of the dc bus 411, and the other end of the brake 401 is connected to the negative terminal 4111 of the dc bus 411. The wind power generator 400 comprises an electric machine 404 and a power conversion circuit 405, wherein the electric machine 404 comprises three-phase armature resistors, the three-phase armature resistors comprise a first armature resistor 407, a second armature resistor 408 and a third armature resistor 409, the power conversion circuit 405 comprises a machine side converter 410 and a dc bus 411 connected with the machine side converter 410, the dc bus 411 comprises a positive terminal 4110 and a negative terminal 4111, and the braking device 401 is connected between the positive terminal 4110 and the negative terminal 4111 of the dc bus 411. In some embodiments, the machine-side converter 410 includes a first power switch 412, a second power switch 413, a third power switch 414, a fourth power switch 415, a fifth power switch 416, and a sixth power switch 417. The motor 404 and the power conversion circuit 405 shown in fig. 13 are similar to the motor 305 and the power conversion circuit 306 shown in fig. 5, and the working principle and the connection mode thereof can refer to the embodiment shown in fig. 5, which is not described herein again.

In some embodiments, the control terminal of the brake device 401 and the control terminal of the power switch are connected to different control ports of a machine-side control device (not shown), so that the power switch and the brake switch 403 can be turned on synchronously. In some other embodiments, the power conversion circuit 405 further includes a brake controller (not shown) electrically connected to the brake switch 403 of the brake device 401 to control the brake switch 403. In some embodiments, the brake controller (not shown) may include any suitable Programmable Circuit or device, such as a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), a Programmable Logic Controller (PLC), an Application Specific Integrated Circuit (ASIC), and so on. In some embodiments, the brake controller may implement control of the brake switch 403 through a combination of hardware and software. In some embodiments, the brake controller and the side control 317 may be controlled synchronously.

In some embodiments, the braking resistor 402 may be a small-resistance braking resistor, and the braking resistor 402 may be an energy consuming unit connected to the dc bus 411, and consumes excess energy when the dc bus voltage of the dc bus 411 is detected to be higher than the normal operating voltage. Compared with the related art shown in fig. 2, for the 2.5MW full-power wind power generator 400, two bleed-off resistors 202 which are originally required to be used can be reduced to one, so that the space in the wind power generator 400 is saved, and for the small-power brake resistor 402, the heat generated is small, and a heat dissipation device is not required to be configured, so that the cost of the wind power generator 400 is reduced.

In other embodiments, an additional energy storage unit is connected to the dc bus 411, and when it is detected that the dc bus voltage of the dc bus 411 is higher than the normal operating voltage, the excess energy is transferred, and after the fault is recovered, the excess stored energy is fed into the grid, for example, the energy storage unit may be a battery or the like. In other embodiments, the capacity of the grid-side converter (not shown) may also be increased, for example by increasing the number of grid-side converters operating in parallel.

Fig. 14 is a flowchart of an embodiment of a method for controlling the power conversion circuit 405 of the wind turbine 400 shown in fig. 13. Compared to the embodiment shown in fig. 6, the method for controlling the power conversion circuit 405 of the wind turbine 400 shown in fig. 14 further includes:

if the voltage of the direct current bus is higher than a first preset value, controlling the brake switch 403 to be switched on, so that the brake resistor 402 is communicated with the direct current bus 411, and discharging the electric energy of the direct current bus 411;

if the voltage of the dc bus is lower than a second preset value, the brake switch 403 is controlled to be turned off to disconnect the brake resistor 402 and the dc bus 411, and the bleeding is ended, wherein the second preset value is lower than the first preset value.

Specifically, as shown in fig. 14, the control method includes steps S1, S4, S5. Wherein the content of the first and second substances,

step S1 is to obtain the dc bus voltage of the dc bus 411. Similar to step S1 of the control method shown in fig. 6, reference may be made to the embodiment shown in fig. 6, and details are not repeated here.

Step S4, if the voltage of the dc bus is higher than the first preset value, the power switch of the machine-side converter 410 is controlled to be turned on, and the brake switch 403 is controlled to be turned on, so that the armature resistor and the brake resistor 402 of the motor 404 are communicated with the dc bus 411, and the electric energy of the dc bus 411 is discharged. The method for controlling the conduction of the power switch of the part of the machine-side converter 410 is similar to the corresponding method shown in fig. 6, and reference may be made to the embodiment shown in fig. 6, which is not described herein again. In some embodiments, when the dc bus voltage is higher than the first preset value, the brake switch 403 may be controlled to be turned on at the same time when the power switch of the portion controlling the machine-side converter 410 is turned on. In the embodiment shown in fig. 14, a bleed resistor is added, and not only the armature resistor but also the braking resistor 402 is used as a bleed resistor to communicate with the dc bus 411 to bleed off the electric energy of the dc bus 411, so that the bleed speed is increased, and the bleed time is shortened.

Step S5, if the voltage of the dc bus is lower than a second preset value, the power switch of the machine-side converter 410 is controlled to be turned off, and the brake switch 403 is controlled to be turned off, so as to disconnect the armature resistor of the motor 404, the brake resistor 402 and the dc bus 411, and terminate the discharging, where the second preset value is lower than the first preset value. In the embodiment shown in fig. 14, a method for controlling turning off of the power switch of the part of the machine-side converter 410 is also similar to the corresponding method shown in fig. 6, and reference may be made to the embodiment shown in fig. 6, which is not described herein again. In some embodiments, when the dc bus voltage is lower than the second preset value, and the power switch of the portion controlling the machine-side converter 410 is turned off, the brake switch 403 may be simultaneously controlled to be turned off to disconnect the armature resistor of the motor 404, the brake switch 403 and the dc bus, and the bleeding is ended.

Fig. 15 is a waveform diagram of the bleed voltage of the dc bus 411, the bleed current of the armature resistor, and the bleed current of the brake resistor 402. Taking a full-power 3300kW wind turbine generator 400 as an example, when the wind turbine generator 400 operates at a rated power, the active power of the machine-side converter 410 is 3300kW, and when the active power transmitted by the machine-side converter 410 is greater than the active power transmitted by the grid-side converter (not shown), so that the dc bus voltage rises to a first preset value 1180V, in combination with any one of the embodiments in fig. 14 and 11 or 12, the armature resistor and the brake resistor 402 of the motor 404 are used as a bleed-off resistor to communicate with the dc bus 411, and the dc bus voltage is pulled down to a second preset value 1120V to bleed off the electric energy of the dc bus 411, so that the dc bus voltage of the dc bus 411 can be controlled within a voltage bearing range, and the normal grid-connected operation of the motor 404 can be ensured, thereby protecting the motor 404, the dc bus 414, and the wind turbine generator 400 from being damaged. Compared to the related art shown in fig. 2, reducing the number of the braking devices 401 can save space in the wind power generator 400, and does not require the addition of a heat sink, thereby reducing the cost of the wind power generator 400. In fig. 15, a waveform 702 is a waveform diagram of a bleed voltage of the dc bus 411, an abscissa is time, an ordinate is voltage, a waveform 703 is a waveform diagram of a bleed current of the armature resistor, an abscissa is time, an ordinate is current, a waveform 704 is a waveform diagram of a bleed current of the brake resistor 402, an abscissa is time, and an ordinate is current. As shown in fig. 15, the peak value of the bleed-off voltage of the brake resistor 402 is about 1700A, and the peak value of the bleed-off current of the armature resistor is about 2900A. In some embodiments, the switching of the grid-side converter (not shown) is operating normally and is not affected. In some embodiments, the peak value of the bleed voltage of the brake resistor 402 and the peak value of the bleed current of the armature resistor may be measured using an oscilloscope.

In some embodiments, any of the above embodiments is selected according to the capacity of the dc bus 411 and the power value of the wind turbine 400. In some embodiments, when the power of the motor 404 is low and the capacitance of the dc bus 411 is not large, the additional brake resistor 402 of the brake device 401 may not need to be added for discharging. When the power of the motor 404 is large and the capacity of the dc bus 411 is large, an additional brake resistor 402 of the brake device 401 needs to be added for discharging.

Corresponding to the foregoing embodiments of the control method of the power conversion circuit 306 of the wind power generator 300, the present application also provides an embodiment of a control apparatus of the power conversion circuit 306 of the wind power generator 300.

Fig. 16 is a schematic diagram of an embodiment of a control device 500 of a power conversion circuit of a wind turbine according to the present application. In some embodiments, the control apparatus 500 comprises one or more processors 501 for implementing the method of controlling the power conversion circuitry of a wind turbine of any of the embodiments of the method of controlling the power conversion circuitry of a wind turbine described above.

The embodiment of the control device 500 of the power conversion circuit of the wind turbine generator can be applied to the wind turbine generator. Embodiments of the control device 500 may be implemented by software, or by hardware, or by a combination of hardware and software. Taking a software implementation as an example, as a logical device, the device is formed by reading corresponding computer program instructions in the nonvolatile memory into the memory for operation through the processor 501 of the wind turbine in which the device is located. From a hardware level, as shown in fig. 16, the present application is a hardware structure diagram of a wind turbine where a control device 500 is located, except for a processor 501, a memory, a network interface, and a nonvolatile memory shown in fig. 16, the wind turbine where the device is located in the embodiment may also include other hardware according to the actual function of the wind turbine, which is not described again.

In some embodiments, the Processor 501 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, and so on. A general purpose processor may be a microprocessor or the processor 501 may be any conventional processor or the like. And will not be described in detail herein.

In some embodiments, the control device 500 shown in fig. 16 can refer to the control device 307 shown in fig. 4 above, and is not described herein again.

FIG. 17 is a schematic diagram of one embodiment of a wind turbine 600 of the present application. As shown in fig. 17, wind turbine generator 600 includes power conversion circuit 601, motor 602, and control device 500 of the power conversion circuit of the wind turbine generator shown in fig. 16.

In some embodiments, the power conversion circuit 601 is connected to the motor 602 for converting electric energy output by the motor 602, the power conversion circuit 601 includes a machine-side converter 6010, a dc bus 6011, and a grid-side inverter 6012, the machine-side converter 6010 is electrically connected to the motor 602, the dc bus 6011 is electrically connected to the machine-side converter 6010, and the grid-side inverter 6012 is electrically connected to the dc bus 6011. In some embodiments, the control device 600 is electrically connected to the side converter 6010.

In some embodiments, the control apparatus 500 comprises one or more processors 501 for implementing the method of controlling the power conversion circuitry of a wind turbine of any of the preceding embodiments of the method of controlling the power conversion circuitry of a wind turbine. In some embodiments, the control device 500 may control a power switch of a portion of the machine-side converter 6010 to be turned on, so that an armature resistor of the motor 602 is used as a discharge resistor and is communicated with the dc bus 6011, so as to discharge electric energy of the dc bus 6011, and when the dc bus voltage rises, the dc bus voltage is controlled within a voltage tolerance range, so as to ensure normal grid-connected operation of the motor 602, and thus protect the motor 602, the dc bus 6011, and the wind turbine 600 from being damaged.

In some embodiments, the power conversion circuit 601, the machine-side converter 6010, and the grid-side converter 6012 shown in fig. 17 may refer to the power conversion circuit 306, the machine-side converter 314, and the grid-side converter 315 shown in fig. 4, which are not described herein again.

The implementation process of the functions and actions of each unit in the control device is specifically described in the implementation process of the corresponding step in the method, and is not described herein again.

For the device embodiments, since they substantially correspond to the method embodiments, reference may be made to the partial description of the method embodiments for relevant points. The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of the application. One of ordinary skill in the art can understand and implement it without inventive effort.

The present application also provides a computer-readable storage medium having stored thereon a computer program which, when executed by the processor 501, implements the wind turbine control method of any of the first aspects. In some embodiments, the computer readable storage medium may be an internal storage unit, such as a hard disk or a memory, of the wind turbine described in any of the previous embodiments. The computer readable storage medium may also be an external storage device of the wind turbine, such as a plug-in hard disk, a Smart Media Card (SMC), an SD Card, a Flash memory Card (Flash Card), etc. provided on the device. Further, the computer readable storage medium may also comprise both an internal storage unit of the wind turbine and an external storage device. The computer-readable storage medium is used for storing the computer program and other programs and data required by the wind turbine, and may also be used for temporarily storing data that has been output or is to be output.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the scope of protection of the present application.

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Wind driven generator and control method and device of power conversion circuit of wind driven generator

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