CN109120206A - The DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system - Google Patents
The DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system Download PDFInfo
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- CN109120206A CN109120206A CN201710488535.1A CN201710488535A CN109120206A CN 109120206 A CN109120206 A CN 109120206A CN 201710488535 A CN201710488535 A CN 201710488535A CN 109120206 A CN109120206 A CN 109120206A
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- electric engine
- current
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- grid
- feedback electric
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- 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
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/085—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
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- 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
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/22—Current control, e.g. using a current control loop
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- 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
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
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- Control Of Eletrric Generators (AREA)
Abstract
The invention discloses a kind of DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system, steady-state performance with higher, and the DC current of system is reduced under conditions of not changing power factor of electric network, to increase lifetime of system.The system includes generator-side converter wear, grid-side converter, pusher side filter, net side filter and d. c. reactor.Pusher side filter is connected between the control winding of double feedback electric engine and generator-side converter wear, net side filter is connected between three-phase alternating-current supply and grid-side converter, and generator-side converter wear is connected with grid-side converter and d. c. reactor is connected between the pusher side emitter of generator-side converter wear and the net side collector of grid-side converter；Moreover, the power winding of double feedback electric engine is by access three-phase alternating-current supply.This method includes that the control winding offer excitation of double feedback electric engine makes the side currents reduction and current on line side increase, and the controller controls the side currents and is equal to the current on line side.
Description
Technical field
The present invention relates to asynchronous machine, in particular to a kind of double feedback electric engine frequency conversion speed-adjusting system based on current source converter
DC bus current control system.
Background technique
The current transformer that double feedback electric engine frequency conversion speed-adjusting system currently on the market uses is mostly thyristor current transformer or voltage
PWM converter, but the circuit topological structure of this current transformer, there are limitation, this limitation is shown: it is not easy to realize more
The parallel connection of a current transformer, so that the total capacity of current transformer is limited；Short-circuit protection is insensitive；It is not good enough with voltage ride through ability.Electric current
Source current transformer includes RB-IGBT derailing switch structure in parallel, inverse-impedance type derailing switch RB-IGBT switch frequency with higher itself
Rate is able to achieve faster dynamic response so that this current source converter has lesser induction reactance and capacitive reactance.
Therefore, for the double feedback electric engine frequency conversion speed-adjusting system using current source converter, due to current source converter itself
Architectural characteristic, it is also desirable to propose a kind of effective controlling party that can be effectively increased the systematic steady state characteristic, increase lifetime of system
Method.
Summary of the invention
In the present invention, the present invention provides a kind of double feedback electric engine frequency conversion speed-adjusting system based on current source converter it is straight
Bus current control system is flowed, the reactive circular power flow between side is exchanged with grid-side converter by control motor stator, enables duplex feeding
The stator winding of machine provides a part of excitation, so that the side currents reduce and the current on line side increases, thus should
The near minimum value of the DC bus current of system, to reduce system loss.
In order to achieve the above object, a kind of DC bus optimal control method of double feedback electric engine frequency conversion speed-adjusting system is provided,
The double feedback electric engine frequency conversion speed-adjusting system includes:
Double feedback electric engine and the mechanical load being connected with the rotor of the double feedback electric engine；
Generator-side converter wear is connected with the control winding of the double feedback electric engine；
Pusher side filter, be connected to the exchange side ports of the generator-side converter wear and be located at the double feedback electric engine with institute
It states between generator-side converter wear；
Grid-side converter is connected with the generator-side converter wear and accesses AC network；
Net side filter, be connected to the exchange side ports of the grid-side converter and be located at the AC network with it is described
Between grid-side converter；
D. c. reactor is connected between the pusher side filter and the net side filter；
The power winding of the double feedback electric engine is directly accessed the AC network；
Controller, the electric signal that input quantity obtains for systematic survey unit, the control algolithm proposed by this patent,
PWM drive signal needed for exporting generator-side converter wear and grid-side converter, for controlling the side currents of the generator-side converter wear
With the current on line side of the grid-side converter, generator-side converter wear and grid-side converter are current source type converters.
This patent provides a kind of DC bus current of double feedback electric engine frequency conversion speed-adjusting system based on current source converter
Control system exchanges with grid-side converter the reactive circular power flow between side by control motor stator, enable the stator of double feedback electric engine around
Group provides a part of excitation, so that the side currents reduce and the current on line side increases, thus by the direct current of the system
The near minimum value of bus current, to reduce system loss.
Preferably, the generator-side converter wear uses stator magnetic linkage oriented vector control method, has for realizing to stator
Function and idle decoupling control.
Preferably, the grid-side converter uses the vector control method of grid voltage orientation, for maintaining DC current
It is constant.
Preferably, the system also includes DC bus optimal control module, the DC bus optimal control module roots
According to Idc_ref_gsc=Idc_ref_rscThe DC current of the system is controlled, wherein Idc_ref_rsc is the straight of the grid-side converter
Current reference value is flowed, Idc_ref_gsc is the reference value of the DC current of the generator-side converter wear.
Preferably, the system does not include three-phase alternating-current supply, the power winding of the double feedback electric engine, the net side unsteady flow
Device is connected with a load.
Preferably, the system also includes:
Crowbar device, the crowbar device be connected to the double feedback electric engine control winding and the pusher side filter it
Between；
Chopper device, the chopper device are in parallel with the d. c. reactor；
Grid-connected contactor, the grid-connected contactor be connected on the transformer and the double feedback electric engine power winding it
Between, for switching on and off the connection of the double feedback electric engine Yu the three-phase alternating-current supply.
Preferably, the grid-side converter is also used to provide reactive power to the three-phase alternating-current supply.
Preferably, the power factor of electric network of the double feedback electric engine frequency conversion speed-adjusting system is kept constant.
It should be understood that above-mentioned each technical characteristic of the invention and having in below (eg embodiment) within the scope of the present invention
It can be combined with each other between each technical characteristic of body description, to form a new or preferred technical solution.As space is limited, exist
This no longer tires out one by one states.
Detailed description of the invention
Fig. 1 is opening up for the double feedback electric engine frequency conversion speed-adjusting system based on current source converter in one embodiment of the present of invention
Flutter structural schematic diagram.
Fig. 2 is the topology knot of the dual feedback wind power generation system based on current source converter in another embodiment of the present invention
Structure schematic diagram.
Fig. 3 is the logic control block diagram of the generator-side converter wear in one embodiment of the present of invention.
Fig. 4 is the logic control block diagram of the grid-side converter in one embodiment of the present of invention.
Fig. 5 a, Fig. 5 b are respectively 2MW double-fed blower typical power curve and speed curves schematic diagram.
Stator of the Fig. 6 for the double feedback electric engine in one embodiment of the present of invention under supersynchronous, synchronous and subsynchronous operating point
The relational graph of compensating power and wind speed.
Stator of the Fig. 7 for the double feedback electric engine in one embodiment of the present of invention under supersynchronous, synchronous and subsynchronous operating point
The relational graph of DC current and wind speed before and after compensating reactive power.
Fig. 8 a, Fig. 8 b are for the double feedback electric engine in one embodiment of the present of invention under supersynchronous, synchronous and subsynchronous operating point
Double feedback electric engine DC current and torque profile figure.
When Fig. 9 a, Fig. 9 b are the operating point variation in one embodiment of the present of invention, network voltage and the power grid electricity of system
The waveform diagram of stream.
When Figure 10 a, Figure 10 b are the operating point variation in one embodiment of the present of invention, double feedback electric engine stator voltage and fixed
The waveform diagram of electron current.
When Figure 11 a, Figure 11 b are the operating point variation in one embodiment of the present of invention, grid-side converter voltage and current
Waveform diagram.
Specific embodiment
The present inventor after extensive and in-depth study, develops a kind of double feedback electric engine based on current source converter for the first time
Frequency conversion speed-adjusting system, generator-side converter wear and grid-side converter use PWM current source type converter.
Term
As used herein, term " decoupling control " refers to using certain structure, finds suitable control law to eliminate system
In the relationship that intercouples between each control loop, so that each input is only controlled a corresponding output, each output is again
The effect only controlled by one.
As used herein, term " power factor " refers in alternating current circuit, the phase difference (Φ) between voltage and electric current it is remaining
String is called power factor, is indicated with symbol cos Φ, and numerically, power factor is the ratio of active power and apparent energy, i.e.,
Cos Φ=P/S.
Double feedback electric engine frequency conversion speed-adjusting system based on current source converter
For the present invention for the conventional fed System based on voltage source converter, major advantage includes: (a) when double
When the working condition variation of generating aid when (for example, switching to synchronize from supersynchronous operating point), current source converter dynamic response is fast,
It highly shortened system voltage, electric current is kept for the transit time of stable state；(b) due to the circuit knot of current source converter itself
Structure, therefore there is stronger short-circuit protection ability, and the parallel connection of multiple current transformers easy to accomplish.
Present invention will be further explained below with reference to specific examples.It should be understood that these embodiments are merely to illustrate the present invention
Rather than it limits the scope of the invention.
It should be noted that in the claim and specification of this patent, such as first and second or the like relationship
Term is only used to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying
There are any actual relationship or orders between these entities or operation.Moreover, the terms "include", "comprise" or its
Any other variant is intended to non-exclusive inclusion so that include the process, methods of a series of elements, article or
Equipment not only includes those elements, but also including other elements that are not explicitly listed, or further include for this process,
Method, article or the intrinsic element of equipment.In the absence of more restrictions, being wanted by what sentence " including one " limited
Element, it is not excluded that there is also other identical elements in the process, method, article or apparatus that includes the element.
Embodiment 1
All references mentioned in the present invention is incorporated herein by reference, independent just as each document
It is incorporated as with reference to such.In addition, it should also be understood that, after reading the above teachings of the present invention, those skilled in the art can
To make various changes or modifications to the present invention, such equivalent forms equally fall within model defined by the application the appended claims
It encloses.
The present invention provides a kind of double feedback electric engine frequency conversion speed-adjusting system based on current source converter.Fig. 1 is of the invention
The topological structure schematic diagram of the double feedback electric engine frequency conversion speed-adjusting system 100 based on current source converter in one embodiment.
As shown in Figure 1, the double feedback electric engine frequency conversion speed-adjusting system include: double feedback electric engine 2 and with the double feedback electric engine 2
The connected mechanical load 3 of rotor；Generator-side converter wear 4 is connected with the control winding of the double feedback electric engine 2；Pusher side filter 6, even
Connect the exchange side ports in the generator-side converter wear 4 and positioned at the double feedback electric engine 2 between the generator-side converter wear 4；
Grid-side converter 5 is connected with the generator-side converter wear 4 and accesses AC network；Net side filter 7 is connected to the net side
Exchange side ports of current transformer 6 and between the AC network and the grid-side converter 6；D. c. reactor 8, connection
Between the pusher side filter 6 and the net side filter 7；The power winding of the double feedback electric engine 2 is directly accessed the friendship
Galvanic electricity net；Controller, the electric signal that input quantity obtains for systematic survey unit, the control algolithm proposed by this patent,
PWM drive signal needed for exporting generator-side converter wear 4 and grid-side converter 5, for controlling the pusher side electricity of the generator-side converter wear 4
The current on line side of stream and the grid-side converter 5.
Specifically, generator-side converter wear and grid-side converter are using RB-IGBT (inverse-impedance type derailing switch) parallel-connection structure
Current source converter.
Generator-side converter wear includes the derailing switch that multiple groups are connected in parallel, and derailing switch described in every group includes the inverse of two series connections
Resistance type IGBT9 simultaneously has collector and emitter, and the collector of derailing switch described in every group constitutes the pusher side of the generator-side converter wear 4
Collector, the emitter of derailing switch described in every group constitute the pusher side emitter of the generator-side converter wear 4；
Grid-side converter 5 is identical as 4 structure of generator-side converter wear and arrangement is on the contrary, the grid-side converter 5 includes more
The derailing switch that group is connected in parallel, derailing switch described in every group include two series connection reverse blocking IGBTs 9 and have collector and
Emitter, the collector of derailing switch described in every group constitute the net side collector of the grid-side converter 5, derailing switch described in every group
Emitter constitutes the net side emitter of the grid-side converter 5；
The pusher side emitter of generator-side converter wear 4 is connected with the net side collector of the grid-side converter 5 and the direct current
Inductor is connected between the pusher side emitter and the net side collector；The pusher side collector of the generator-side converter wear and institute
The net side emitter for stating grid-side converter 5 is connected；
The control winding of double feedback electric engine 2 is connected with the generator-side converter wear 4, and the pusher side filter 6 includes multiple parallel connections
The pusher side capacitor of connection is simultaneously connected between the control winding of the double feedback electric engine and the input side of the cleaning toilet current transformer；
The net side filter 7 include multiple net side capacitors being connected in parallel and it is multiple respectively with the net side capacitor
The net side inductor of series connection, the grid-side converter 5 are accessed the three-phase alternating-current supply, 7 quilt of net side filter
It is connected between the grid-side converter 5 and the three-phase alternating-current supply；
The power winding of the double feedback electric engine is accessed the three-phase alternating-current supply.
In this embodiment, three-phase alternating-current supply refers to AC network, is also possible to threephase load, such as transformer etc..
Mechanical load 3 is connect with the shaft of double feedback electric engine 2, when mechanical load 3 carries out mechanical rotation, drives double fed electric machine rotor rotation
And voltage and current is generated, it is incorporated to AC network and powers to power grid；In turn, AC network can be by the system to duplex feeding
Machine power supply, thus the mechanical movement of double feedback electric engine control mechanical load.
Moreover, the system is also installed with controller, the electric parameter for measuring system controls signal, such as: stator electricity
Pressure, electric current, rotor voltage, electric current, double feedback electric engine machinery rotational angle etc.；It is also used to measured control signal feeding back to machine
The steady-state performance of side current transformer 4, grid-side converter 5 and double feedback electric engine 2 and control system.
In this embodiment, double fed asynchronous machine (1)-(4) can be controlled according to the following formula:
The power of double fed asynchronous machine can then be controlled according to formula (5):
Wherein U represents voltage, and I represents electric current, and ψ represents magnetic linkage, subscript behalf stator, and subscript r represents rotor.ωsIt is same
Angular frequency is walked, ω is electromechanics angular frequency, and s is revolutional slip, npIt is the number of pole-pairs of motor, J is the rotary inertia of motor, TeIt is
Electromagnetic torque, TLIt is load torque.LmIt is magnetizing inductance, LsIt is stator equivalent self inductance, LrIt is rotor equivalent self-induction.Ps, Qs, Pr, Qr
Be respectively double feedback electric engine (DFIG) stator it is active, stator is idle, rotor is active, rotor is idle.Indicate that motor turns with subscript d
The direct-axis component of son, subscript q then indicate the quadrature axis component of rotor.
Fig. 3 is the logic control block diagram of the generator-side converter wear in one embodiment of the present of invention, specifically, in the implementation
In example, it is assumed that the reference value of electromagnetic power is Pe_ref, the reactive power that stator side provides is Qs_ref.Generator-side converter wear is using fixed
The vector control mode of sub- flux linkage orientation.
Under conditions of stator magnetic linkage oriented, ψ can be enabledsd=ψs, ψsq=0, that is, ignore transient, stator resistance and rotor
Resistance, being derived according to formula (1)-(2) can be obtained formula (6):
Rotor current d axis component and q axis component are controlled according to formula (10), solution active to stator and idle may be implemented
Coupling control, this control mode can be improved the steady-state performance of system 100.
As shown in figure 3, the electromagnetic power reference value of entire double feedback electric engine frequency conversion speed-adjusting system is Pe_ref, stator reactive power
Reference value be Qs_ref, double fed electric machine rotor electric current q axis component is obtained according to formula (6)With d axis componentSuddenly based on Kiel
Husband's current law, the electric current for flowing into generator-side converter wear is equal to the sum of rotor current and rotor capacitance current of double feedback electric engine, in Fig. 4
IcrdAnd IcrqThe respectively d axis component and q axis component of rotor capacitance current can pass through respectively formula (7)~(8) and calculate
It arrives:
That is, Icrd=-s ωsCRSCUrq——(7)
Icrq=s ωsCRSCUrd——(8)
Wherein, wherein s be motor revolutional slip, ωsIt is synchronous angular frequency, CRSCIt is that (i.e. rotor is simultaneously for generator-side converter wear capacitor
Join capacitor), UrdAnd UrqRespectively represent the d axis component and q axis component of rotor capacitance voltage.
The d axis component of rotor current obtains flowing into the electricity of generator-side converter wear with the d axis component of rotor capacitance current after being added
The d axis component I of streamRSC_d, the q axis component of rotor current obtained after being added with the q axis component of rotor capacitance current flow into pusher side become
Flow the q axis component I of the electric current of deviceRSC_q, IRSC_dAnd IRSC_q6 road PWM are exported after space vector modulation (SVM) algoritic module
Wave (pulse width modulation wave), also,SVM algorithm module is also inputted as rotor phase angle.
Above-mentioned 6 tunnel PWM wave is input in generator-side converter wear (not to be shown for controlling 6 switching tubes of generator-side converter wear in Fig. 1
On off operating mode out), thus pusher side three-phase current I needed for outputRSC_abc.The lower right corner Fig. 4 is the electric loop of pusher side, the electricity
Air circuit includes parameter: the capacitor C of pusher side converter unsteady flow sideRSC, inductance LRSCWith resistance RRSC.Moreover, the electric loop is used for
The signal of measurement & characterization double feedback electric engine power state, and further the resulting signal of measurement is coordinately transformed for system
Control.Needed included in Fig. 4 measurement signal include but is not limited to: rotor three-phase voltage URSC_abc, rotor three-phase electric current
Irabc, stator three-phase current Isabc, stator three-phase voltage UsabcAnd the mechanical angle θ that rotor turns overr.Fig. 4 includes coordinate
Conversion module 2r/3s, 2r/2s and 2s/3s.
Rotor three-phase voltage URSC_abcRotor dq shaft voltage U is converted to by 2r/3s moduleRSC_dq；Rotor three-phase electric current
IrabcI is converted to by 2r/3s modulerdq；The mechanical angle θ that rotor turns overrIt is obtained by derivative module d/dt differential
To the mechanical angular velocity omega of rotorr；Stator three-phase current IsabcIt is converted under two-phase stationary coordinate system by 2s/3s module
Stator biphase current Isαβ, and further across 2r/2s module from IsαβBe converted to the stator two-phase come under two cordic phase rotators
Electric current Isdq；Stator three-phase voltage UsabcThe stator biphase current U under two-phase stationary coordinate system is converted to by 2s/3s modulesαβ,
And further across 2r/2s module from UsαβBe converted to the stator biphase current U come under two cordic phase rotatorssdq。
Further, the lower left corner Fig. 3 is double feedback electric engine stator flux observer, for according to stator voltage UsαβAnd electric current
IsαβTo estimate the amplitude ψ of stator magnetic linkagesAnd phase angleControling parameter as double feedback electric engine frequency conversion speed-adjusting system.
Further, the DC current reference value I of generator-side converter weardc_ref_rscFor
Fig. 4 is the control block diagram of the grid-side converter in one embodiment of the present of invention, which uses and be based on
The control mode of grid voltage orientation vector controlled.Grid-side converter is for maintaining the DC current of the frequency conversion speed-adjusting system steady
It is fixed, while a certain amount of reactive power is injected to power grid, so that grid-connected current can satisfy the power factor command of power grid.
As shown in figure 4, the DC bus current of the system (following " system " refers both to " frequency conversion speed-adjusting system of the invention ")
Reference value beActual value is Idc, the difference of two current signals obtains the active of net side grid-connected current after PI controller
ComponentWith the d axis component I of net side capacitance currentcidObtain flowing into the d axis component I of the electric current of grid-side converter after additionGSC_d。
The reactive component of net side grid-connected currentFor preset value, in one embodiment,It can be 0.Grid-side converter and machine
The electrical structure of side current transformer is similar, flow into grid-side converter electric current be equal to net side grid-connected current and net side capacitance current it
With it is, the reactive component of net side grid-connected currentWith the q axis component I of net side capacitance currentciqIt obtains flowing into net after addition
The q axis component I of the electric current of side current transformerGSC_q.Wherein, IcidAnd IciqIt is calculated respectively according to formula (10)-(11):
Icid=-ωsCGSCUgq——(10)
Icrq=ωsCGSCUgd——(11)
Wherein ωsIt is synchronous angular frequency, CGSCIt is grid-side converter capacitor, UgdAnd UgqRepresent the d axis point of net side capacitance voltage
Amount and q axis component.
Electric current IGSC_dAnd IGSC_qBy exporting 6 tunnel PWM waves after space vector modulation (SVM) algoritic module, the PWM wave is defeated
Enter to grid-side converter to be used to control the on off operating mode of 6 switching tubes of grid-side converter, thus net side three-phase needed for output
Electric current IGSC_abc.The lower right corner Fig. 5 is the electric loop of grid-side converter, which includes the electricity of grid-side converter exchange side
Hold CGSC, inductance LGSCWith resistance RGSC, and there is also grid-connected line inductance L between the electric loop and AC networkg.Into one
Step ground, the electric loop are used for the signal of measurement & characterization double feedback electric engine power state, and further to measure resulting signal into
Row coordinate transform for system to control.Needed included in Fig. 5 measurement signal include but is not limited to: grid-side converter three-phase
Three-phase voltage UGSC_abc, grid-connected three-phase current Igabc, power grid three-phase voltage Ugabc；It further include coordinate transformation module 2r/3s, 2r/2s
And 2s/3s.
Grid-side converter three-phase voltage UGSC_abcRotor dq shaft voltage U is converted to by 2r/3s moduleGSC_dq；Grid-connected three-phase
Electric current IgabcI is converted to by 2r/3s modulegdq；Power grid three-phase voltage UgabcTwo-phase static coordinate is converted to by 2r/3s module
Network voltage U under systemgdq, and further across net side PLL (phaselocked loop) according to UgdqNet side phase angle θ is calculatedgWith from
The net side angular velocity omega that net side calculatesg。
Further, the control block diagram of grid-side converter according to Fig.4, controller can control grid-side converter friendship
Flow the voltage and current of side.
In view of unity power factor to be realized is run to meet the grid-connected requirement of the system, therefore the power of double feedback electric engine
The reactive power that the reactive power that winding (stator side) provides is provided with grid-side converter must offset each other.Grid-side converter is adopted
With the vector control method of grid voltage orientation as shown in Figure 4, in this embodiment, Ugd=Ug,Ugq=0.It is kept according to energy
Constant rule, the active power that grid-side converter provides are slip powerReactive power is-Qs_ref.?
In the embodiment, include the filter inductance in net side filter voltage drop it is negligible, and in net side filter
Electric current on filter capacitor cannot then be ignored, therefore grid-side converter electric current is represented by
It is to further calculate out rotor-side converter DC current reference value
Still in this embodiment, double feedback electric engine frequency conversion speed-adjusting system 100 uses DC bus optimal control method, this method
It is run for control system in the case where DC current is minimized.Specifically, this method comprises: by double feedback electric engine function
Rate winding (stator side) provides a part of reactive power, so that the electric current of the control winding (rotor-side) of double feedback electric engine be made to reduce simultaneously
And to increase from the electric current that grid-side converter flows into AC network simultaneously；When the two is equal, controller controls double feedback electric engine
According to formula Idc_ref_gsc=Idc_ref_rscIt is controlled.By to Idc_ref_gsc=Idc_ref_rscIt is solved, it is available fixed
Son needs reactive power Q to be offereds_refFormula (14):
WhereinIn formula
LsFor motor stator equivalent self inductance, LrFor rotor equivalent self inductance, LmFor motor excitation inductance, k is the equivalent change of machine winding
Than,For stator flux of motor amplitude, ωsFor motor synchronous rotary angular frequency, s is motor slip ratio, VgFor network voltage width
Value, CgFor net side filter capacitor, Pe_refFor the electromagnetic power reference value of whole system.
This method in terms of existing technologies, can further decrease the DC current values of system, so that DC loop
Active loss with current transformer reaches minimum, improves running efficiency of system；The hair of resistance caused by DC current can also be reduced
Heat and current stress, thus optimize the system operation, the lifting system service life.
Embodiment 2
Double feedback electric engine frequency conversion speed-adjusting system based on current source converter
Fig. 2 is the topology knot of the dual feedback wind power generation system based on current source converter in one embodiment of the present of invention
Structure.The topological structure includes transformer 18 (access three-phase alternating-current supply), double feedback electric engine and with the double feedback electric engine shaft phase
Wind energy conversion system 10 even；Further include: generator-side converter wear 4, grid-side converter 5, pusher side filter 6, net side filter 7 and direct current
Sensor 8；
The generator-side converter wear 4 includes the derailing switch that multiple groups are connected in parallel, and derailing switch described in every group includes that two series connection connect
The reverse blocking IGBT that connects simultaneously has collector and emitter, and the collector of derailing switch described in every group constitutes the generator-side converter wear
Pusher side collector, the emitter of derailing switch described in every group constitute the pusher side emitter of the generator-side converter wear；
The grid-side converter is identical as the generator-side converter wear structure and arrangement is on the contrary, the grid-side converter includes more
The derailing switch that group is connected in parallel, derailing switch described in every group include the reverse blocking IGBT of two series connections and have collector and hair
Emitter-base bandgap grading, the collector of derailing switch described in every group constitute the net side collector of the grid-side converter, the hair of derailing switch described in every group
Emitter-base bandgap grading constitutes the net side emitter of the grid-side converter；
The pusher side emitter of the generator-side converter wear is connected and described straight with the net side collector of the grid-side converter
Galvanic electricity sensor is connected between the pusher side emitter and the net side collector；The pusher side collector of the generator-side converter wear with
The net side emitter of the grid-side converter is connected；
The control winding of the double feedback electric engine is connected with the generator-side converter wear, and the pusher side filter includes multiple parallel connections
The pusher side capacitor of connection is simultaneously connected between the control winding of the double feedback electric engine and the input side of the cleaning toilet current transformer；
The net side filter include multiple net side capacitors being connected in parallel and it is multiple respectively with the net side capacitor
The net side inductor of series connection, the grid-side converter are accessed the three-phase alternating-current supply, and the net side filter is connected
It connects between the grid-side converter and the three-phase alternating-current supply；
The power winding of the double feedback electric engine is accessed the three-phase alternating-current supply.
Further, topological structure shown in Fig. 2 further include:
Crowbar device 15, the crowbar device be connected to the double feedback electric engine control winding and the pusher side filter
Between；
Chopper device 16, the chopper device are connected on the both ends of the d. c. reactor；
Grid-connected contactor 17, the grid-connected contactor be connected on the transformer and the double feedback electric engine power winding it
Between, for switching on and off the connection of the double feedback electric engine Yu the three-phase alternating-current supply.
Wherein, the shaft of double feedback electric engine is directly connected with the shaft of wind energy conversion system 10, while wind energy conversion system 10 can also be equipped with speedup
Device 11 (raising speed gear-box), brake 12, variable pitch unit 13, yaw device 14 etc..
In a test case, wind energy conversion system 10 (wind-driven generator) builds simulation model according to topological structure shown in Fig. 2,
And using the parameter of 2MW doubly-fed wind turbine, parameter is as shown in table 1.
1 2MW double feedback electric engine parameter table of table
Current transformer is designed with filter using the parameter of table 2:
2 current transformer of table and filter parameter table
Wherein, the resonance frequency theoretical value of pusher side filter is 800Hz, and the resonance frequency theoretical value of net side filter is
400Hz, maximum DC ripple theoretical value are 40A.
Fig. 5 is then the power curve and speed curves schematic diagram of 2MW wind energy conversion system.Wind energy conversion system includes three kinds of working conditions: super
It is synchronous, synchronous and subsynchronous.Therefore the operating point for choosing these three corresponding states respectively carries out simulation analysis, for example, according to Fig. 6
Choose: supersynchronous operating point is wind speed 16m/s, motor speed 1800rpm, mechanical output 2000kW；Synchronous working point is wind speed
6.7m/s, motor speed 1500rpm, mechanical output 400kW；And subsynchronous operating point is wind speed 5.5m/s, motor speed
1200rpm, mechanical output 200kW.
Then static Simulation analysis is carried out to the double-fed blower fan power generation system using simulation software, it is shown in Fig. 2 to test
The superiority and inferiority of the frequency control ability of system based on current source converter.Specifically, (super according to above-mentioned three kinds of operating points first
It is synchronous, synchronous, subsynchronous) nothing provided for the power winding of double feedback electric engine needed for DC bus optimal control method is provided
Function power (also known as " stator is idle ")；Then, it according to formula (1)~(10), brings the parameter of table 1~2 into simulation software, counts
It calculates and obtains that stator in the system 200 is idle, relation curve of DC current and wind speed.The relation curve is as shown in figs. 6-7.
Stator of the Fig. 6 for the double feedback electric engine in one embodiment of the present of invention under supersynchronous, synchronous and subsynchronous operating point
The relational graph of compensating power and wind speed.From fig. 6, it can be seen that stator issues idle 0.395pu under supersynchronous operating point, directly
Galvanic electricity stream 802A optimizes amplitude 2.8%；The lower stator of synchronous working point issues idle 0.184pu, DC current 200A, optimizes width
Degree 34.7%；Stator issues idle 0.157pu, DC current 148A under subsynchronous operating point, optimizes amplitude 44.2%.
Stator of the Fig. 7 for the double feedback electric engine in one embodiment of the present of invention under supersynchronous, synchronous and subsynchronous operating point
The relational graph of DC current and wind speed before and after compensating reactive power.As can be seen from FIG. 7, wind speed is smaller, the optimization amplitude of DC current
Bigger, when blower is in certain subsynchronous states, the optimization amplitude of DC current can even reach 50% or more, and this is meaned
Smaller Converter Capacity, it is smaller loss and lower cost.
Double-fed of the Fig. 8 for the double feedback electric engine in one embodiment of the present of invention under supersynchronous, synchronous and subsynchronous operating point
The DC current and torque profile figure of motor.As shown in figure 8, with the variation of wind speed, at 1s the and 1.5s moment, fan operation point
From it is supersynchronous become synchronization become subsynchronous again.Wherein supersynchronous operating point DC current theoretical value 802A, simulation result 802A；
Synchronous working point DC current theoretical value 200A, simulation result 200A；Subsynchronous operating point DC current theoretical value 148A, emulation
As a result 148A.Revolving speed is 60 π rad/s, theoretical torque -10610Nm, actual torque -10689Nm when supersynchronous operating point；It is synchronous
Revolving speed is 50 π rad/s, theoretical torque -2546Nm, actual torque -2422Nm when operating point；Revolving speed is 40 when subsynchronous operating point
π rad/s, theoretical torque -1592Nm, actual torque -1547Nm.Notional result is consistent with simulation result, it was demonstrated that set forth herein
DC bus current Optimized-control Technique have very high stable state accuracy.In addition, becoming synchronous regulating time from supersynchronous
For 0.16s (8 power frequency periods), become hyposynchronous regulating time from synchronizing as 0.04s (2 power frequency periods), this shows this
DC bus current optimal control method used by system 200 has preferable dynamic property.
When Fig. 9~11 are respectively the operating point variation in one embodiment of the present of invention, the network voltage and power grid of system
The waveform of the waveform diagram of electric current, the waveform diagram of double feedback electric engine stator voltage and stator current and grid-side converter voltage and current
Figure.Every width figure includes two parts in left and right, and the parameter that wherein left side reflects supersynchronous operating point when becoming synchronous working point becomes
Change waveform, and the Parameters variation waveform that the right then reflects synchronous working point when becoming subsynchronous operating point.It can be with from Fig. 9~11
Find out, when wind energy conversion system operating point changes, the power winding of double feedback electric engine and the power factor of grid-side converter side are constantly sent out
It is raw to change, but the circuit for being incorporated to AC network can then remain that unity power factor is run, and grid-connected current harmonic wave total amount is small
In 5%, meet grid-connected requirement.
In conclusion the present invention has the advantages that the double feedback electric engine frequency conversion speed-adjusting system based on current source converter it is straight
Stream bus current optimal control method can guarantee that whole system has outstanding dynamic property and steady-state performance, can adapt to more
The different operating conditions of kind；It is possible to further continue to reduce DC current under conditions of not changing power factor of electric network, to reduce
Capacity, cost and the volume of current transformer reduce the thermal losses and thermal stress of current transformer, increase lifetime of system；In addition, this method is only
Control algolithm need to be changed, without adding any extra means, dramatically save equipment cost and maintenance cost.
Presently preferred embodiments of the present invention has already been described in detail above, it is understood that having read of the invention above-mentioned say
After awarding content, those skilled in the art can make various modifications or changes to the present invention.Such equivalent forms equally fall within this
Apply for the appended claims limited range.
Claims (8)
1. a kind of DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system, which is characterized in that the double feedback electric engine
Frequency conversion speed-adjusting system includes:
Double feedback electric engine and the mechanical load being connected with the rotor of the double feedback electric engine；
Generator-side converter wear is connected with the control winding of the double feedback electric engine；
Pusher side filter, be connected to the exchange side ports of the generator-side converter wear and be located at the double feedback electric engine with the machine
Between the current transformer of side；
Grid-side converter is connected with the generator-side converter wear and accesses AC network；
Net side filter is connected to the exchange side ports of the grid-side converter and is located at the AC network and the net side
Between current transformer；
D. c. reactor is connected between the pusher side filter and the net side filter；
The power winding of the double feedback electric engine is directly accessed the AC network；
Controller, input quantity are the electric signal that systematic survey unit obtains, the control algolithm proposed by this patent, output
PWM drive signal needed for generator-side converter wear and grid-side converter, for controlling side currents and the institute of the generator-side converter wear
The current on line side of grid-side converter is stated, generator-side converter wear and grid-side converter are current source type converters.
2. the DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system as described in claim 1, which is characterized in that
The generator-side converter wear uses stator magnetic linkage oriented vector control method, for realizing the decoupling control active and idle to stator
System.
3. the DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system as described in claim 1, which is characterized in that
The grid-side converter uses the vector control method of grid voltage orientation, for maintaining DC current constant.
4. the DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system as described in claim 1, which is characterized in that
The system also includes DC bus optimal control module, the DC bus optimal control module is according to Idc_ref_gsc=
Idc_ref_rscThe DC current of the system is controlled, wherein Idc_ref_rsc is that the DC current of the grid-side converter refers to
Value, Idc_ref_gsc are the reference value of the DC current of the generator-side converter wear.
5. the DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system as described in claim 1, which is characterized in that
The system does not include three-phase alternating-current supply, and the power winding of the double feedback electric engine, the grid-side converter are connected with a load.
6. the DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system as described in claim 1, which is characterized in that
The system also includes:
Crowbar device, the crowbar device are connected between the control winding of the double feedback electric engine and the pusher side filter；
Chopper device, the chopper device are in parallel with the d. c. reactor；
Grid-connected contactor, the grid-connected contactor are connected between the transformer and the power winding of the double feedback electric engine, are used
In the connection for switching on and off the double feedback electric engine Yu the three-phase alternating-current supply.
7. the DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system as claimed in claim 3, which is characterized in that
The grid-side converter is also used to provide reactive power to the three-phase alternating-current supply.
8. the DC bus current control system of double feedback electric engine frequency conversion speed-adjusting system as claimed in claim 3, which is characterized in that
The power factor of electric network of the double feedback electric engine frequency conversion speed-adjusting system is kept constant.
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| CN110112743A (en) * | 2019-04-04 | 2019-08-09 | 上海电力学院 | A kind of isolated form variable-frequency transformer and its starting control and expansion method |
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