CN113315115A - Direct-current grid-connected structure of multiphase wind power generation system and control method thereof - Google Patents

Direct-current grid-connected structure of multiphase wind power generation system and control method thereof Download PDF

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CN113315115A
CN113315115A CN202110360796.1A CN202110360796A CN113315115A CN 113315115 A CN113315115 A CN 113315115A CN 202110360796 A CN202110360796 A CN 202110360796A CN 113315115 A CN113315115 A CN 113315115A
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phase
isolated
bridge
grid
capacitor
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CN113315115B (en
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杨光源
周诗嘉
辛清明
王振
彭光强
武霁阳
冯雷
徐爽
潘烙
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China South Power Grid International Co ltd
Maintenance and Test Center of Extra High Voltage Power Transmission Co
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China South Power Grid International Co ltd
Maintenance and Test Center of Extra High Voltage Power Transmission Co
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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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H02J1/12—Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/006—Means for protecting the generator by using control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2101/00—Special adaptation of control arrangements for generators
    • H02P2101/15—Special adaptation of control arrangements for generators for wind-driven turbines
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2103/00—Controlling arrangements characterised by the type of generator
    • H02P2103/20—Controlling arrangements characterised by the type of generator of the synchronous type
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The application discloses a direct current grid-connected structure of a multiphase wind power generation system and a control method thereof, wherein the structure comprises the following steps: the system comprises a multiphase permanent magnet synchronous generator, a three-phase bridge type uncontrolled rectifier and an isolated DC/DC converter. The multiphase permanent magnet synchronous generator comprises a plurality of sets of three-phase windings, and each set of three-phase windings is connected to a high-voltage direct current power grid in a cascading mode after being converted by a three-phase bridge type uncontrolled rectifier and an isolated DC/DC converter. The multiphase permanent magnet synchronous generator has the characteristics of high power, high torque and low torque pulsation, and can still output by reducing power after a certain phase fails, so that the multiphase permanent magnet synchronous generator has a better redundancy characteristic; furthermore, the number of switching devices can be effectively reduced and the cost of the wind power generation system can be reduced by a mode of directly connecting the single-phase half-bridge rectifier in the isolated DC/DC converter in a cascade mode after rectification. Therefore, the technical problems that a traditional three-phase motor grid-connected structure is prone to failure, low in fault tolerance and high in cost are solved.

Description

Direct-current grid-connected structure of multiphase wind power generation system and control method thereof
Technical Field
The application relates to the technical field of new energy power generation, in particular to a direct-current grid-connected structure of a multi-phase wind power generation system and a control method thereof.
Background
With the rapid development of economy, the demand of people on electric energy is continuously expanded, and the traditional fossil energy power generation can not meet the demand of people, so that new energy power generation is vigorously developed in various countries in the world. Wind energy is used as a new energy source with wider coverage, related motor technologies are also mature, and the research and application of wind power generation in China are gradually developed.
The traditional wind power generation adopts a common three-phase motor, but 6 times of torque pulsation can be generated due to interaction of 5 times of harmonic waves of air gap magnetomotive force and fundamental waves, so that a three-phase motor grid-connected structure is easy to break down, and when a certain phase of the traditional three-phase motor grid-connected structure breaks down, a power generation system cannot continue to operate, so that the fault tolerance and reliability of the traditional three-phase motor grid-connected structure are low; and if high-power output is to be realized, a plurality of three-phase motors and transformers are required to be combined, and the traditional single-phase full-bridge uncontrolled rectifier and half-bridge MMC sub-module grid-connected structure is large in number of devices, so that the traditional three-phase motor grid-connected structure is high in cost.
Disclosure of Invention
The embodiment of the application provides a direct-current grid-connected structure of a multi-phase wind power generation system and a control method thereof, and is used for solving the technical problems that a traditional three-phase motor grid-connected structure is prone to failure, low in fault tolerance and high in cost.
In view of the above, a first aspect of the present application provides a dc grid-connected structure of a multi-phase wind power generation system, the structure comprising:
the system comprises a multi-phase permanent magnet synchronous generator, k/3 three-phase bridge type uncontrolled rectifiers and k/3 isolated DC/DC converters; wherein k is the number of phases of the multiphase permanent magnet synchronous generator and is an integral multiple of 3;
the multiphase permanent magnet synchronous generator comprises k/3 sets of three-phase windings, and the mutual difference between any two sets of adjacent three-phase windings is 180 DEG/k of electrical angle;
each set of three-phase winding of the multiphase permanent magnet synchronous generator is respectively connected with the alternating current side of each three-phase bridge type uncontrolled rectifier; the direct-current side positive electrode of the three-phase bridge type uncontrolled rectifier is connected with the input end positive electrode of the isolated DC/DC converter, and the direct-current side negative electrode is connected with the input end negative electrode of the isolated DC/DC converter;
the negative electrode of the output end of each isolated DC/DC converter is connected with the positive electrode of the output end of the adjacent isolated DC/DC converter; and the positive electrode of the output end of the first isolated DC/DC converter is connected with the positive electrode of the high-voltage direct-current power grid, and the negative electrode of the output end of the kth/3 th isolated DC/DC converter is connected with the negative electrode of the high-voltage direct-current power grid.
Optionally, the isolated DC/DC converter specifically includes: the single-phase bridge type inverter comprises a single-phase bridge type inverter, a plurality of single-phase half-bridge rectifiers and a multi-winding transformer; the primary side of the multi-winding transformer is provided with 1 winding, the secondary side of the multi-winding transformer is provided with n windings, the transformation ratio is 1:1, and n is a positive integer;
the output end of the single-phase bridge inverter is connected with the primary side winding of the multi-winding transformer, and the input end of each single-phase half-bridge rectifier is respectively connected with any one of the windings in the secondary side of the multi-winding transformer one by one;
and the input end of the single-phase bridge inverter is connected with the output end of the three-phase bridge type uncontrolled rectifier.
Optionally, the single-phase bridge inverter specifically includes: the IGBT device comprises a first IGBT tube, a second IGBT tube, a third IGBT tube and a fourth IGBT tube;
the collectors of the first IGBT tube and the third IGBT tube are connected to be used as the anode of the input end of the isolated DC/DC converter, and the emitters of the second IGBT tube and the fourth IGBT tube are connected to be used as the cathode of the input end of the isolated DC/DC converter;
the emitting electrode of the first IGBT tube is connected with the collecting electrode of the second IGBT tube, and the connection point is used as the positive electrode of the output end of the single-phase bridge inverter; and the emitter of the third IGBT tube is connected with the collector of the fourth IGBT tube, and the connection point is used as the cathode of the output end of the single-phase bridge inverter.
Optionally, the single-phase half-bridge rectifier specifically includes: the fifth IGBT tube, the sixth IGBT tube, the first capacitor and the second capacitor; wherein the first capacitor and the second capacitor are both rated voltage capacitors;
an emitter of the fifth IGBT tube is connected with a collector of the sixth IGBT tube, and a connection point is used as an input end anode of the single-phase half-bridge rectifier;
the negative electrode of the first capacitor is connected with the positive electrode of the second capacitor, and the connection point is used as the negative electrode of the input end of the single-phase half-bridge rectifier;
a collector of the fifth IGBT tube is connected with the anode of the first capacitor, and a connection point is used as the anode of the output end of the single-phase half-bridge rectifier;
and the emitting electrode of the sixth IGBT tube is connected with the negative electrode of the second capacitor, and the connection point is used as the negative electrode of the output end of the single-phase half-bridge rectifier.
Optionally, the method further comprises: a first filter capacitor;
and the filter capacitor is connected in parallel with the anode and the cathode of the output end of the three-phase bridge type uncontrolled rectifier.
Optionally, the single-phase bridge inverter further comprises: a second filter capacitor;
and the second filter capacitor is connected in parallel with the positive electrode and the negative electrode of the input end of the single-phase bridge inverter.
Optionally, when the rated voltage of the high-voltage direct-current power grid is Uhvdc, the number of the single-phase half-bridge rectifiers included in each of the isolated DC/DC converters is y, where y is 3 × Uhvdc/(2 × k × UC), and UC is the rated voltage of the first capacitor and the second capacitor.
The second aspect of the present application provides a method for controlling a dc grid-connected structure of a multi-phase wind power generation system, the method comprising:
s1, calculating the reference rotating speed of the multiphase permanent magnet synchronous generator according to the current wind speed of the environment where the power generation system is located;
s2, calculating according to the actual rotating speed of the multiphase permanent magnet synchronous generator and the reference rotating speed based on an output current reference value calculation formula to obtain an output current reference value of the three-phase bridge type uncontrolled rectifier;
s3, calculating according to the output current reference value and the actual output current value of the three-phase bridge type uncontrolled rectifier based on a duty ratio calculation formula of the single-phase bridge type inverter to obtain the duty ratio of the single-phase bridge type inverter in the isolated DC/DC converter;
s4, calculating an input current reference value of the single-phase half-bridge rectifier according to the actual output voltage of the single-phase half-bridge rectifier and the voltage value of the first capacitor or the second capacitor based on an input current reference value calculation formula of the single-phase half-bridge rectifier;
and S5, comparing the input current reference value of the single-phase half-bridge rectifier with the input current actual value of the single-phase half-bridge rectifier through a hysteresis comparator, and outputting a control signal of the single-phase half-bridge rectifier.
Optionally, the output current reference value calculation formula is:
Figure BDA0003005465170000041
wherein ,Io_refTo output a current reference value, kp1Is the proportionality coefficient, k, of the first PI regulatori1Is the integral coefficient of the first PI regulator,
Figure BDA0003005465170000042
is an integral factor, omega is the actual rotational speed, omegarefIs the reference rotation speed.
Optionally, the duty ratio of the single-phase bridge inverter is calculated by the following formula:
Figure BDA0003005465170000043
wherein ,DhIs the duty ratio, k, of the single-phase bridge inverter in the h-th isolated DC/DC converterp2Is the proportionality coefficient, k, of the second PI regulatori2Is the integral coefficient of the second PI regulator,
Figure RE-GDA0003173204160000044
as an integration factor, IohIs the actual value of the output current, Ioh_refIs the output current reference value.
According to the technical scheme, the embodiment of the application has the following advantages:
in the embodiment of the application, a direct-current grid-connected structure of a multi-phase wind power generation system is provided, and a multi-phase permanent magnet synchronous generator is adopted, so that low-voltage high-power and high-torque output can be realized; the multiphase permanent magnet synchronous generator has more windings, so that when a certain phase fails, the failed phase can be cut off to realize power transmission reduction, and the multiphase permanent magnet synchronous generator has higher fault tolerance and redundancy; and under the action of stator harmonic current, the output torque pulsation of the multiphase permanent magnet synchronous generator is reduced, so that the system reliability is improved. Further, the isolated DC/DC converter adopted by the application is a single-phase half-bridge rectifier, and compared with the traditional grid-connected structure of a single-phase full-bridge uncontrolled rectifier and a half-bridge MMC sub-module, the number of devices is obviously reduced, and the cost is obviously reduced. Therefore, the technical problems that a traditional three-phase motor grid-connected structure is prone to failure, low in fault tolerance and high in cost are solved.
Drawings
Fig. 1 is a schematic structural diagram of a dc grid-connected structure of a multiphase wind power generation system provided in an embodiment of the present application;
FIG. 2 is a schematic diagram of a multiphase permanent magnet synchronous generator line voltage waveform provided in an embodiment of the present application;
fig. 3 is a grid-connected current waveform diagram of a dc grid-connected structure of a multiphase wind power system according to an embodiment of the present application;
fig. 4 is a schematic flowchart of a control method of a dc grid-connected structure of a multi-phase wind power generation system according to an embodiment of the present application;
fig. 5 is a control block diagram of a control method of a direct-current grid-connected structure of a multi-phase wind power generation system according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments that can be derived by a person skilled in the art from the embodiments given in the present application without making any creative effort shall fall within the protection scope of the present application.
Referring to fig. 1, a schematic structural diagram of a dc grid-connected structure of a multi-phase wind power generation system provided in an embodiment of the present application is shown.
An embodiment one of the dc grid-connected structure of the multiphase wind power generation system provided in the embodiment of the present application includes: the system comprises a multi-phase permanent magnet synchronous generator, k/3 three-phase bridge type uncontrolled rectifiers and k/3 isolated DC/DC converters; wherein k is the number of phases of the multiphase permanent magnet synchronous generator, and k is an integral multiple of 3.
FIG. 2 is a waveform diagram of a line voltage of a multiphase permanent magnet synchronous generator, when a wind speed is 10m/s, a peak value of the line voltage of the multiphase permanent magnet synchronous generator is about 1950V, an effective value of the line voltage is about 690V, and a frequency of the line voltage is about 3.5 Hz; when the wind speed is reduced to 9m/s, the peak-to-peak value of the line voltage of the multiphase permanent magnet synchronous generator is about 1745V, the effective value of the line voltage is about 617V, and the voltage frequency is about 3.07 Hz.
The multiphase permanent magnet synchronous generator comprises k/3 sets of three-phase windings, and the mutual difference between any two adjacent sets of three-phase windings is 180 DEG/k electrical angle.
It should be noted that, as shown in fig. 1, each three phase in the multi-phase permanent magnet synchronous generator of the present application is a set of windings, and k/3 sets of three-phase windings are provided, and each set of windings is connected to a high voltage direct current power grid after being cascaded with a three-phase bridge type uncontrolled rectifier and an isolated DC/DC converter. The number k of phases of the multiphase permanent magnet synchronous generator is 18, the number n of single-phase half-bridge rectifiers contained in each isolated DC/DC converter is 4, the rated power of the multiphase permanent magnet synchronous generator is 2MW, and the constant voltage is 690V. Each set of three-phase winding of the multiphase permanent magnet synchronous generator is respectively connected with the alternating current side of each three-phase bridge type uncontrolled rectifier; and the direct-current side anode of the three-phase bridge type uncontrolled rectifier is connected with the input end anode of the isolated DC/DC converter, and the direct-current side cathode is connected with the input end cathode of the isolated DC/DC converter.
It should be noted that, as shown in fig. 1, DR is a three-phase bridge type uncontrolled rectifier, the left side, i.e., the ac side, of DR is connected to one of three-phase windings of the multiphase permanent magnet synchronous generator, and the anode and the cathode of the output end of the right side, i.e., the DC side, are correspondingly connected to the anode and the cathode of the isolated DC/DC converter, respectively.
The negative electrode of the output end of each isolated DC/DC converter is connected with the positive electrode of the output end of the adjacent isolated DC/DC converter; and the positive electrode of the output end of the first isolated DC/DC converter is connected with the positive electrode of the high-voltage direct-current power grid, and the negative electrode of the output end of the kth/3 th isolated DC/DC converter is connected with the negative electrode of the high-voltage direct-current power grid.
It should be noted that the HVDC + in fig. 1 is the positive electrode of the high voltage dc power grid, and the HVDC-is the negative electrode of the high voltage dc power grid. Wherein the rated voltage of the high-voltage direct-current power grid is 12 kV.
It will be appreciated that the present application includes a plurality of isolated DC/DC converters, each comprising a positive pole and a negative pole, the positive pole of the first isolated DC/DC converter being connected to HVDC + and the negative pole of the first isolated DC/DC converter being connected to HVDC-and the positive and negative poles of each isolated DC/DC converter being connected in parallel relationship. Therefore, the direct-current grid-connected structure of the multiphase wind power generation system is obtained.
FIG. 3 is a waveform diagram of the grid-connected current of the high-voltage direct-current power grid, when the wind speed is 10m/s of the rated wind speed, the current of the high-voltage direct-current power grid is about 158A, and when the wind speed is reduced to 9m/s, the grid-connected current is about 105A due to the reduction of the machine-side power.
The embodiment of the application provides a multiphase wind power generation system direct current grid-connected structure, includes: the system comprises a multiphase permanent magnet synchronous generator, a three-phase bridge type uncontrolled rectifier and an isolated DC/DC converter. The multiphase permanent magnet synchronous generator comprises a plurality of sets of three-phase windings, and each set of three-phase windings is connected to a high-voltage direct current power grid in a cascading mode after being converted by a three-phase bridge type uncontrolled rectifier and an isolated DC/DC converter. The multiphase permanent magnet synchronous generator has the characteristics of high power, high torque and low torque pulsation, and can still output by reducing power after a certain phase fails, so that the multiphase permanent magnet synchronous generator has a better redundancy characteristic; furthermore, the number of switching devices can be effectively reduced and the cost of the wind power generation system can be reduced by a mode of directly connecting the single-phase half-bridge rectifier in the isolated DC/DC converter in a cascade mode after rectification. Therefore, the technical problems that a traditional three-phase motor grid-connected structure is prone to failure, low in fault tolerance and high in cost are solved.
Further, on the basis of the first embodiment, the isolated DC/DC converter of the second embodiment of the present application specifically includes: the single-phase bridge type inverter comprises a single-phase bridge type inverter, a plurality of single-phase half-bridge rectifiers and a multi-winding transformer; the primary side of the multi-winding transformer is provided with 1 winding, the secondary side of the multi-winding transformer is provided with n windings, the transformation ratio is 1:1, and n is a positive integer; the output end of the single-phase bridge inverter is connected with the primary side winding of the multi-winding transformer, and the input end of each single-phase half-bridge rectifier is respectively connected with any one of the windings in the secondary side of the multi-winding transformer one by one; the input end of the single-phase bridge inverter is connected with the output end of the three-phase bridge type uncontrolled rectifier.
It should be noted that, in the second embodiment of the present application, a specific composition and connection structure of the isolated DC/DC converter are provided. It can be understood that the single-phase bridge inverter is connected to the plurality of single-phase half-bridge rectifiers through a multi-winding transformer, the left side, i.e., the primary side, of the multi-winding transformer is the single-phase bridge inverter, the right side, i.e., the secondary side, of the multi-winding transformer includes a plurality of windings, and each winding is connected to each single-phase bridge inverter in a one-to-one correspondence.
Further, on the basis of the second embodiment, the single-phase bridge inverter of the third embodiment specifically includes: the IGBT device comprises a first IGBT tube, a second IGBT tube, a third IGBT tube and a fourth IGBT tube; the collector electrodes of the first IGBT tube and the third IGBT tube are connected to be used as the anode of the input end of the isolated DC/DC converter, and the emitter electrodes of the second IGBT tube and the fourth IGBT tube are connected to be used as the cathode of the input end of the isolated DC/DC converter; the emitting electrode of the first IGBT tube is connected with the collecting electrode of the second IGBT tube, and the connecting point is used as the positive electrode of the output end of the single-phase bridge inverter; and the emitting electrode of the third IGBT tube is connected with the collecting electrode of the fourth IGBT tube, and the connection point is used as the negative electrode of the output end of the single-phase bridge inverter.
It should be noted that, in the third embodiment of the present application, a specific composition and connection structure of a single-phase bridge inverter are provided.
Further, on the basis of the second embodiment, the single-phase half-bridge rectifier according to the fourth embodiment of the present application specifically includes: the fifth IGBT tube, the sixth IGBT tube, the first capacitor and the second capacitor; the first capacitor and the second capacitor are both rated voltage capacitors; an emitter of the fifth IGBT tube is connected with a collector of the sixth IGBT tube, and a connection point is used as an input end anode of the single-phase half-bridge rectifier; the negative electrode of the first capacitor is connected with the positive electrode of the second capacitor, and the connection point is used as the negative electrode of the input end of the single-phase half-bridge rectifier; a collector of the fifth IGBT tube is connected with the anode of the first capacitor, and the connection point is used as the anode of the output end of the single-phase half-bridge rectifier; and an emitting electrode of the sixth IGBT tube is connected with the negative electrode of the second capacitor, and the connection point is used as the negative electrode of the output end of the single-phase half-bridge rectifier.
It should be noted that, the fourth embodiment of the present application provides a specific composition and connection structure of a single-phase half-bridge rectifier. The first capacitor and the second capacitor are both 10mF, and the rated voltage UC is 220V.
Further, on the basis of the first embodiment, the dc grid-connected structure of the multi-phase wind power generation system further includes: a first filter capacitor; the filter capacitor is connected in parallel with the anode and the cathode of the output end of the three-phase bridge type uncontrolled rectifier.
Note that, the size of the first filter capacitor in the present application is 4 mF.
Further, on the basis of the second embodiment, the single-phase bridge inverter further includes: a second filter capacitor; the second filter capacitor is connected in parallel with the positive pole and the negative pole of the input end of the single-phase bridge inverter.
Note that, the size of the second filter capacitor in the present application is 4 mF.
Further, on the basis of the fourth embodiment, when the rated voltage of the high-voltage direct-current power grid is UhvdcAnd the number of the single-phase half-bridge rectifiers contained in each isolated DC/DC converter is y, wherein y is 3Uhvdc/(2*k*UC)，UCIs the rated voltage of the first capacitor and the second capacitor.
It will be appreciated that the number of single phase half bridge rectifiers in the isolated DC/DC converter is determined by the voltage rating of the first and second capacitors, the voltage rating of the high voltage DC network and the number of phases of the multiphase permanent magnet synchronous generator.
The foregoing is an embodiment of a dc grid-connected structure of a multi-phase wind power generation system provided in the embodiment of the present application, and the following is an embodiment of a control method of a dc grid-connected structure of a multi-phase wind power generation system provided in the embodiment of the present application.
Referring to fig. 4 and fig. 5, fig. 4 is a schematic flowchart of a control method of a dc grid-connected structure of a multi-phase wind power generation system according to an embodiment of the present application, and fig. 5 is a control block diagram of a single-phase bridge inverter and a single-phase half-bridge rectifier in the dc grid-connected structure of the multi-phase wind power generation system according to the embodiment of the present application.
It should be noted that the control method provided in the embodiment of the present application is exemplified by calculating the duty ratio and the control signal of one single-phase half-bridge rectifier in the grid-connected structure, and is also applicable to calculating the duty ratios and the control signals of other single-phase half-bridge rectifiers in the grid-connected structure.
The embodiment of the control method for the direct-current grid-connected structure of the multi-phase wind power generation system provided by the embodiment of the application comprises the following steps:
step 201, calculating a reference rotating speed of the multiphase permanent magnet synchronous generator according to the current wind speed of the environment where the power generation system is located.
It should be noted that, the blade radius R and the optimal tip speed ratio λ of the multiphase permanent magnet synchronous generator given in the data manual in the embodiments of the present applicationoptCalculating a reference rotation speed omegaref。
In particular, the method comprises the following steps of,
Figure BDA0003005465170000081
and v is the current wind speed of the environment where the power generation system is located.
And 202, calculating according to the actual rotating speed and the reference rotating speed of the multi-phase permanent magnet synchronous generator based on an output current reference value calculation formula to obtain an output current reference value of the three-phase bridge type uncontrolled rectifier.
Wherein, the output current reference value calculation formula is as follows:
Figure BDA0003005465170000082
wherein ,Io_refTo output a current reference value, kp1Is the scaling factor of the first PI regulator,ki1is the integral coefficient of the first PI regulator,
Figure BDA0003005465170000095
is an integral factor, omega is the actual speed, omegarefIs the reference rotational speed.
It should be noted that, in the embodiment of the present application, the actual rotational speed ω of the multiphase permanent magnet synchronous generator is detected by the resolver, and ω are detectedrefMaking a difference, and passing the difference result through a first PI regulator, wherein the output of the first PI regulator is the output current reference value I of the three-phase bridge type uncontrolled rectifiero_ref。
And 203, calculating according to the output current reference value and the actual output current value of the three-phase bridge type uncontrolled rectifier based on a duty ratio calculation formula of the single-phase bridge type inverter to obtain the duty ratio of the single-phase bridge type inverter in the isolated DC/DC converter.
The duty ratio calculation formula of the single-phase bridge inverter is as follows:
Figure BDA0003005465170000091
in the formula ,DhIs the duty ratio, k, of a single-phase bridge inverter in the h-th isolated DC/DC converterp2Is the proportionality coefficient, k, of the second PI regulatori2Is the integral coefficient of the second PI regulator,
Figure BDA0003005465170000092
as an integration factor, IohTo output a current reference value, Ioh_refIs the actual value of the output current.
It can be understood that, in the embodiment of the present application, by calculating the duty ratio of the single-phase bridge inverter, the duty ratio of the conduction time of the IGBT tube of the single-phase bridge inverter can be known, so as to control the switching state of the IGBT tube.
It should be noted that, in the embodiment of the present application, the actual output current I of the three-phase bridge type uncontrolled rectifier is detected by the current transformerohIs shown byohAnd Ioh_refMaking difference, making the difference result pass through second PI regulator, and making the output of second PI regulator be duty ratio D of single-phase bridge type inverter in h isolated type DC/DC converterh。
And 204, calculating an input current reference value of the single-phase half-bridge rectifier according to the actual output voltage of the single-phase half-bridge rectifier and the voltage value of the first capacitor or the second capacitor based on an input current reference value calculation formula of the single-phase half-bridge rectifier.
The calculation formula of the input current reference value of the single-phase half-bridge rectifier is as follows:
Figure BDA0003005465170000093
in the formula ,Iih_x_refIs the input current reference value, k, of a single-phase half-bridge rectifierp3Is the proportionality coefficient, k, of a third PI regulatori3Is the integration coefficient of the third PI regulator,
Figure BDA0003005465170000094
as an integral factor, UCh_xFor the x single-phase half-bridge rectifier in the h winding set, UCIs the voltage of the filter capacitor, thetah_xThe synchronous phase angle of the input voltage of the x single-phase half-bridge rectifier in the h-th set of windings.
It should be noted that, in the embodiment of the present application, the actual output voltage U of the xth single-phase half-bridge rectifier in the h set of windings is detected through the voltage transformerCh_xX is 1, 2, …, n; the synchronous phase angle theta of the input voltage of the x single-phase half-bridge rectifier in the h winding is then determined according to the phase-locked loop PLLh_xWill U isCh_xDivide by 2 and then with UCMaking a difference, passing the difference result through a third PI regulator, and multiplying the output of the third PI regulator by sin thetah_xObtaining the input current reference value I of the x single-phase half-bridge rectifier in the h set of windingsih_x_ref。
And step 205, comparing the input current reference value of the single-phase half-bridge rectifier with the input current actual value of the single-phase half-bridge rectifier through the hysteresis comparator, and outputting a control signal of the single-phase half-bridge rectifier.
It should be noted that, in the embodiment of the present application, the actual input current I of the xth single-phase half-bridge rectifier in the h set of winding is detected through the current transformerih_xThen, mixing Iih_xAnd Iih_x_refPassing through a hysteresis comparator, the output of the hysteresis comparator is the control signal S of the x single-phase half-bridge rectifier in the h set of windingsh_x。
The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicates that there may be three relationships, for example, "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the contextual objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and in actual implementation, there may be other divisions, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
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 units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a hardware form, and can also be realized in a software functional unit form.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims (10)

1. A multiphase wind power generation system direct current grid-connected structure is characterized by comprising: the system comprises a multi-phase permanent magnet synchronous generator, k/3 three-phase bridge type uncontrolled rectifiers and k/3 isolated DC/DC converters; wherein k is the number of phases of the multiphase permanent magnet synchronous generator and is an integral multiple of 3;
the multiphase permanent magnet synchronous generator comprises k/3 sets of three-phase windings, and the mutual difference between any two sets of adjacent three-phase windings is 180 DEG/k of electric angle;
each set of three-phase winding of the multiphase permanent magnet synchronous generator is respectively connected with the alternating current side of each three-phase bridge type uncontrolled rectifier; the direct-current side positive electrode of the three-phase bridge type uncontrolled rectifier is connected with the input end positive electrode of the isolated DC/DC converter, and the direct-current side negative electrode is connected with the input end negative electrode of the isolated DC/DC converter;
the negative electrode of the output end of each isolated DC/DC converter is connected with the positive electrode of the output end of the adjacent isolated DC/DC converter; and the positive electrode of the output end of the first isolated DC/DC converter is connected with the positive electrode of the high-voltage direct-current power grid, and the negative electrode of the output end of the kth/3 th isolated DC/DC converter is connected with the negative electrode of the high-voltage direct-current power grid.
2. The multiphase wind power system direct current grid-connected structure according to claim 1, wherein the isolated DC/DC converter specifically comprises: the single-phase bridge type inverter comprises a single-phase bridge type inverter, a plurality of single-phase half-bridge rectifiers and a multi-winding transformer; the primary side of the multi-winding transformer is provided with 1 winding, the secondary side of the multi-winding transformer is provided with n windings, the transformation ratio is 1:1, and n is a positive integer;
the output end of the single-phase bridge inverter is connected with the primary side winding of the multi-winding transformer, and the input end of each single-phase half-bridge rectifier is respectively connected with any one of the secondary sides of the multi-winding transformer one by one;
and the input end of the single-phase bridge inverter is connected with the output end of the three-phase bridge type uncontrolled rectifier.
3. The multiphase wind power system dc grid-connected structure of claim 2, wherein the single-phase bridge inverter specifically comprises: the IGBT device comprises a first IGBT tube, a second IGBT tube, a third IGBT tube and a fourth IGBT tube;
the collectors of the first IGBT tube and the third IGBT tube are connected to be used as the anode of the input end of the isolated DC/DC converter, and the emitters of the second IGBT tube and the fourth IGBT tube are connected to be used as the cathode of the input end of the isolated DC/DC converter;
the emitting electrode of the first IGBT tube is connected with the collecting electrode of the second IGBT tube, and the connection point is used as the positive electrode of the output end of the single-phase bridge inverter; and the emitter of the third IGBT tube is connected with the collector of the fourth IGBT tube, and the connection point is used as the cathode of the output end of the single-phase bridge inverter.
4. The multiphase wind power system dc grid-connected structure of claim 2, wherein the single-phase half-bridge rectifier specifically comprises: the fifth IGBT tube, the sixth IGBT tube, the first capacitor and the second capacitor; the first capacitor and the second capacitor are both rated voltage capacitors;
an emitter of the fifth IGBT tube is connected with a collector of the sixth IGBT tube, and a connection point is used as an input end anode of the single-phase half-bridge rectifier;
the negative electrode of the first capacitor is connected with the positive electrode of the second capacitor, and the connection point is used as the negative electrode of the input end of the single-phase half-bridge rectifier;
a collector electrode of the fifth IGBT tube is connected with the positive electrode of the first capacitor, and a connection point is used as the positive electrode of the output end of the single-phase half-bridge rectifier;
and an emitting electrode of the sixth IGBT tube is connected with a negative electrode of the second capacitor, and a connection point is used as a negative electrode of an output end of the single-phase half-bridge rectifier.
5. The multiphase wind power system dc grid-connected structure of claim 1, further comprising: a first filter capacitor;
and the filter capacitor is connected in parallel with the anode and the cathode of the output end of the three-phase bridge type uncontrolled rectifier.
6. The multiphase wind power system dc grid-connection architecture of claim 2, wherein said single-phase bridge inverter further comprises: a second filter capacitor;
and the second filter capacitor is connected in parallel with the positive electrode and the negative electrode of the input end of the single-phase bridge inverter.
7. The multiphase wind power system DC grid connection architecture of claim 4,
when the rated voltage of the high-voltage direct-current power grid is UhvdcWhen the number of the single-phase half-bridge rectifiers contained in each isolated DC/DC converter is y, wherein y is 3Uhvdc/(2*k*UC)，UCIs the rated voltage of the first capacitor and the second capacitor.
8. A method for controlling a dc grid-connected structure of a multi-phase wind power generation system, which is applied to the dc grid-connected structure of the multi-phase wind power generation system according to any one of claims 1 to 7, comprising:
s1, calculating the reference rotating speed of the multiphase permanent magnet synchronous generator according to the current wind speed of the environment where the power generation system is located;
s2, calculating according to the actual rotating speed of the multiphase permanent magnet synchronous generator and the reference rotating speed based on an output current reference value calculation formula to obtain an output current reference value of the three-phase bridge type uncontrolled rectifier;
s3, calculating according to the output current reference value and the actual output current value of the three-phase bridge type uncontrolled rectifier based on a duty ratio calculation formula of the single-phase bridge type inverter to obtain the duty ratio of the single-phase bridge type inverter in the isolated DC/DC converter;
s4, calculating an input current reference value of the single-phase half-bridge rectifier according to the actual output voltage of the single-phase half-bridge rectifier, the synchronous phase angle of the input voltage of the single-phase half-bridge rectifier, and the rated voltage value of the first capacitor or the second capacitor based on an input current reference value calculation formula of the single-phase half-bridge rectifier;
and S5, comparing the input current reference value of the single-phase half-bridge rectifier with the input current actual value of the single-phase half-bridge rectifier through a hysteresis comparator, and outputting a control signal of the single-phase half-bridge rectifier.
9. The method according to claim 7, wherein the output current reference value calculation formula is:
Figure FDA0003005465160000031
wherein ,Io_refTo output a current reference value, kp1Is the proportionality coefficient, k, of the first PI regulatori1Is the integral coefficient of the first PI regulator,
Figure FDA0003005465160000032
is an integral factor, omega is the actual rotational speed, omegarefIs the reference rotation speed.
10. The method for controlling the direct-current grid-connected structure of the multi-phase wind power generation system according to claim 7, wherein the duty ratio of the single-phase bridge inverter is calculated according to the formula:
Figure FDA0003005465160000033
wherein ,DhIs the duty cycle, k, of the single-phase bridge inverter in the h-th isolated DC/DC converterp2Is the proportionality coefficient, k, of the second PI regulatori2Is the integral coefficient of the second PI regulator,
Figure FDA0003005465160000034
as an integration factor, IohIs the actual value of the output current, Ioh_refIs the output current reference value;
the calculation formula of the input current reference value of the single-phase half-bridge rectifier is as follows:
Figure FDA0003005465160000035
in the formula ,Iih_x_refIs the input current reference value, k, of a single-phase half-bridge rectifierp3Is the proportionality coefficient, k, of a third PI regulatori3Is the integration coefficient of the third PI regulator,
Figure FDA0003005465160000036
as an integral factor, UCh_xFor the x single-phase half-bridge rectifier in the h winding set, UCIs the rated voltage of the first capacitor or the second capacitor, thetah_xThe synchronous phase angle of the input voltage of the x single-phase half-bridge rectifier in the h set of windings.
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CN103280838A (en) * 2013-05-29 2013-09-04 浙江大学 Wind power generation high-voltage direct current grid-connected system based on open coil structure and control method thereof
CN106452098A (en) * 2016-09-09 2017-02-22 湖南大学 High-voltage and large-power wind power generation system and control method thereof
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