CN107658911A - Permanent magnet direct-drive Wind turbines strengthen low voltage traversing control method under unbalanced grid faults - Google Patents
Permanent magnet direct-drive Wind turbines strengthen low voltage traversing control method under unbalanced grid faults Download PDFInfo
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- CN107658911A CN107658911A CN201711012383.4A CN201711012383A CN107658911A CN 107658911 A CN107658911 A CN 107658911A CN 201711012383 A CN201711012383 A CN 201711012383A CN 107658911 A CN107658911 A CN 107658911A
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- 230000002441 reversible effect Effects 0.000 claims description 32
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- 238000006243 chemical reaction Methods 0.000 claims description 11
- 230000005611 electricity Effects 0.000 claims description 11
- 230000001360 synchronised effect Effects 0.000 claims description 10
- 238000000819 phase cycle Methods 0.000 claims description 9
- 238000011217 control strategy Methods 0.000 claims description 7
- 238000009790 rate-determining step (RDS) Methods 0.000 claims description 6
- 230000004907 flux Effects 0.000 claims description 3
- 230000006641 stabilisation Effects 0.000 claims description 3
- 238000011105 stabilization Methods 0.000 claims description 3
- 238000010977 unit operation Methods 0.000 abstract description 2
- 230000002708 enhancing effect Effects 0.000 description 8
- 230000008859 change Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000005389 magnetism Effects 0.000 description 3
- 230000001629 suppression Effects 0.000 description 3
- 238000004146 energy storage Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
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- 230000004888 barrier function Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
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- 238000005859 coupling reaction Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
-
- H02J3/386—
-
- 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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Abstract
The invention discloses permanent magnet direct-drive Wind turbines under a kind of unbalanced grid faults to strengthen low voltage traversing control method, is related to the control to permanent magnet direct-drive Wind turbines grid side converter and machine-side converter.This method obtains the given instruction of positive and negative sequence dq shaft currents of permanent magnet direct-drive Wind turbines grid side converter, further by the positive and negative sequence control voltage of obtained grid side converter on the basis of converter capacity and unit operation operating mode is taken into full accountWith DC bus-bar voltage UdcGrid side converter PWM drive signal is produced by space vector modulation, permanent magnet direct-drive Wind turbines are enabled to suppress grid entry point voltage unbalance factor, and watt current is provided to power network to greatest extent, so as to significantly enhance the quality of power supply of low voltage ride-through capability of the permanent magnet direct-drive Wind turbines under unbalanced grid faults and its institute simultaneously power network.
Description
Technical field
The present invention relates to wind generating technology, and in particular to a kind of permanent magnet direct-drive Wind turbines are under unbalanced grid faults
Enhancing fault traversing control method, belong to technical field of new energy power generation.
Background technology
At present, permanent magnet direct-drive Wind turbines eliminate the failures such as gear-box, brush, slip ring because it uses permanent magnet excitation
The higher part of rate, have the advantages that resisting salt fog corrosion, simple in construction and running noises are small, have become wind generator system
In one of mainstream model.Isolate because permanent magnet direct-drive Wind turbines realize machine net by total power converter, make full use of
The capacity of total power converter compensates to the voltage of wind power plant common point, is to improve permanent magnet direct-drive Wind turbines fault traversing
The Main Means of ability.And in view of China's wind power resources have focused largely on remote districts, it is weaker with electric power major network connection, compared to
Power network symmetrical short-circuit failure, the probability that power network asymmetry short circuit fault occurs in systems in practice are bigger.When power network generation is not right
When title falls failure, electricity generation system will export substantial amounts of negative-sequence current, and producing grid-connected converter, imbalance is generated heat, loss increases
Greatly, serious threat grid-connected converter runnability and electricity generation system and network electric energy quality；Secondly, unbalanced source voltage can also be made
Power into electricity generation system feed-in power network vibrates, and causes electricity generation system DC-link voltage to fluctuate, has a strong impact on electricity generation system
With the safe and stable operation of power network.Therefore, in order to improve low-voltage of the permanent magnet direct-drive Wind turbines under unbalanced grid faults
Ride-through capability and Wind turbines and power network the quality of power supply, need further to permanent magnetism direct drive wind under unbalance grid fault condition
The low voltage traversing control method of electric system is furtherd investigate.At present, for the unbalanced fault of permanent magnet direct-drive Wind turbines
Crossing technology, domestic and foreign scholars have carried out correlative study, such as published following documents：
(1) Zhang Xiaoying, Cheng Zhizhuan, Li Chen, Dingning, Jiang save directly-drive permanent magnet wind generatings system in unbalance grid failure
Under Voltage Stability Control [J] electric power system protection and controls .2013,41 (18):17-24.
(2) Zhu little Jun, Yao Jun, Jiang Kun, summer pioneer, Wen Yiyu, imperial rainbow are given birth list containing flywheel energy storage under unbalanced grid faults
Permanent magnet direct-drive wind power system enhancing operation control strategy [J] electric power network techniques of member, 2013,37 (5):1454-1463.
Document (1) is using double-current ring control strategy under double synchronization rotational coordinate ax systems, or realizes that non-negative sequence current exports
To power network, or realize that active power of output and the double-frequency fluctuation of DC side busbar voltage 2 are effectively suppressed, or realize that output is idle
Power improves the fault ride-through capacity of permanent magnet direct-drive wind power system, but can not realize simultaneously multiple to a certain extent without fluctuation
Operational objective.Document (2) by the dc bus of converter install additional energy storage device with absorb the double-frequency fluctuation of DC capacitor 2 with
And the active power of generator output is so as to maintain DC bus-bar voltage stable and without fluctuation, and eliminated by grid side converter defeated
Go out the negative sequence component of electric current or 2 double-frequency fluctuations of power output, strengthen the fault ride-through capacity of wind power system and grid-connected system
The quality of power supply of system, but the capacity of grid side converter is not given full play to, and the use of hardware device will necessarily increase entirely
The cost of system.
, will necessarily be to forever due to the appearance of electrical network negative phase-sequence voltage and system negative-sequence current during unbalanced grid faults
The runnability of the directly driven wind-powered unit of magnetic is produced and had a strong impact on.Therefore, it is fully sharp on the basis of extra hardware device is not increased
With the capacity of current transformer in permanent magnet direct-drive Wind turbines and controllable ability, permanent magnet direct-drive wind turbine under unbalanced grid faults is studied
The enhancing low voltage traversing control method of group, so as to ensure that permanent magnet direct-drive Wind turbines off-grid safe and stable operation and do not suppress
The degree of unbalancedness of grid entry point voltage, further to improve power network transient voltage level, the event to enhancing permanent magnet direct-drive wind power system
Simultaneously the quality of power supply of power network has important practical significance for barrier ride-through capability and its institute.
The content of the invention
For deficiencies of the prior art, it is an object of the invention to propose under a kind of unbalanced grid faults forever
The directly driven wind-powered unit enhancing low voltage traversing control method of magnetic, this method make full use of net side in permanent magnet direct-drive Wind turbines to convert
Device capacity suppresses grid entry point voltage unbalance factor, and to greatest extent provides watt current to power network, straight so as to improve permanent magnetism
Wind dispelling group of motors fault ride-through capacity and its simultaneously network electric energy quality.
The technical proposal of the invention is realized in this way：
Permanent magnet direct-drive Wind turbines strengthen low voltage traversing control method under unbalanced grid faults, and this method is related to forever
The control of the directly driven wind-powered unit grid side converter of magnetic and machine-side converter；
(A) rate-determining steps of permanent magnet direct-drive Wind turbines grid side converter are：
A1 permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal u) is gatheredgabc, grid side converter output three-phase current
Signal igabcAnd DC bus-bar voltage signal Udc；
A2) the permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal u that will be collectedgabcBy digital phase-locked loop PLL
The electrical angle θ of permanent magnet direct-drive Wind turbines grid entry point positive sequence voltage vector is obtained afterwardsgWith synchronous angular rate ωe；
A3) by permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal ugabcBy static three-phase abc coordinate systems to quiet
The only invariable power coordinate transform of the two-phase α β systems of axis, the voltage signal under the convert to static two-phase α β systems of axis, i.e. ugα、
ugβ；
A4 permanent magnet direct-drive Wind turbines grid entry point positive sequence voltage d axle oriented approach) is used, respectively by step A3) gained it is quiet
The only voltage signal u under the two-phase α β systems of axisgα、ugβThrough the static two-phase α β systems of axis to positive, reverse sync angular speed rotation
Turn the invariable power conversion of the system of axis, then by 2 ωeTrapper filters, and obtains permanent magnet direct-drive Wind turbines grid entry point three-phase electricity
It is pressed in the forward direction during running under the conditions of unbalanced grid faults, the dq axles point under reverse sync angular speed rotational coordinates shafting
Amount, i.e.,
A5) the grid side converter three-phase current signal i that will be collectedgabcBy the static three-phase abc systems of axis to static
The invariable power coordinate transform of the two-phase α β systems of axis obtains the output current i under the static two-phase α β systems of axisgα、igβ；
A6) by step A5) grid side converter output current i under the static two-phase α β systems of axis of gainedgα、igβThrough static two
The phase α β systems of axis convert to positive, reverse sync angular speed rotational coordinates shafting invariable power, then by 2 ωeTrapper is filtered
Ripple, dq axis component of the grid side converter output current under positive, reverse sync angular speed rotating coordinate system is obtained, i.e.,
A7) by step A4) obtained by permanent magnet direct-drive Wind turbines grid entry point voltage reverse sync angular speed rotate sit
Dq axis components under mark system, i.e.,Grid side converter negative-sequence current reference value computing module is delivered to, according to the following formula really
During determining unbalanced grid faults operation, grid side converter can suppress grid entry point voltage unbalance factor to output needed for zero
Negative-sequence current reference value without amplitude limit
In formula, Kp1And τi1The respectively proportionality coefficient of negative-sequence current reference value computing module pi regulator and the time of integration
Constant；
A8) by step A4) obtained wind farm grid-connected voltage is under positive, reverse sync angular speed rotating coordinate system
Dq axis componentsAnd step A7) obtained negative-sequence current reference value of the grid side converter without amplitude limitGrid side converter forward-order current maximum amplitude computing module is delivered to, according to the following formula, is determined under negative-sequence current limitation
Permanent magnet direct-drive wind power system can be output the amplitude of forward-order current：
In formula, | igmax| the maximum current amplitude allowed to flow through for grid side converter；
A9) by step A4) obtain permanent magnet direct-drive Wind turbines grid side converter in reverse sync angular speed rotational coordinates
Dq shaft voltage components under systemAnd step A6) and step A8) obtain permanent magnet direct-drive Wind turbines net side conversion
Dq shaft current component of the device under positive, reverse sync angular speed rotating coordinate systemAnd grid side converter
Allow the maximum current i of operationgmaxThe positive and negative sequence current reference value computing module of grid side converter is delivered to, determines that net side converts
The positive and negative sequence current reference value of device
A10) by step A9) the grid side converter positive sequence, the negative-sequence current reference value that are calculated be delivered to net side change respectively
Parallel operation positive sequence, negative-sequence current inner ring controlling unit, according to the following formula, grid side converter are obtained in positive, reverse sync speed angular speed
Positive and negative sequence control voltage dq axis components under rotating coordinate system control
In formula, Kp3And τi3The proportionality coefficient of current inner loop PI controllers respectively in grid side converter positive sequence control system
And integration time constant, Kp4And τi4The proportionality coefficient of electric current loop PI controllers respectively in grid side converter negative phase-sequence control system
And integration time constant, LgFor the inductance of the reactor of grid side converter；
A11) by step A10) obtained positive and negative sequence control voltage dq axis components of grid side converter WithPoint
Not Jing Guo the positive, invariable power of reverse sync angular speed rotational coordinates shafting to the static two-phase α β systems of axis convert to obtain it is static
Positive and negative sequence control voltage under the two-phase α β systems of axis
A12) by step A11) the obtained positive and negative sequence control voltage of grid side converterWith DC bus-bar voltage Udc
Grid side converter PWM drive signal is produced by space vector modulation, to suppress unbalanced source voltage degree；
(B) rate-determining steps of permanent magnet direct-drive Wind turbines machine-side converter are：
B1) permanent magnet direct-drive Wind turbines machine-side converter uses vector control strategy, and its control voltage passes through space vector
Pulsewidth modulation produces machine-side converter PWM drive signal, female with permanent magnet direct-drive Wind turbines direct current during maintaining unbalanced fault
The stabilization of line voltage.
Further, described step A9) comprise the steps of：
A9.1) unbalanced grid faults operation during, utilize step A7) obtain the grid side converter negative phase-sequence without amplitude limit
Electric current dq axle reference valuesCalculate grid side converter negative-sequence current reference value amplitudeWith grid side converter positive sequence electricity
Flow reference value amplitude
And carry out following judgement：
In formula,Forward direction synchronous angular velocity rotating coordinate system when realizing maximal wind-power tracking for permanent magnet direct-drive Wind turbines
Lower net side d shaft current positive-sequence components,For not output reactive power when forward direction synchronous angular velocity rotating coordinate system under net side q axles
Electric current positive-sequence component；
A9.2) if meeting A9.1) in constraints, the positive and negative sequence dq shaft current reference values of grid side converter are according to such as
Under the output：
In formula,For the output of grid side converter positive and negative sequence current reference value computing module just,
Negative phase-sequence dq shaft current reference values；
A9.3) if being unsatisfactory for A9.1) in constraints, judgment step A9.1) obtain permanent magnet direct-drive Wind turbines
Grid side converter negative-sequence current reference value amplitudeWhether the constraints that satisfaction is shown below：
A9.4) if meeting A9.3) in constraints, the positive and negative sequence dq shaft current reference values of grid side converter are according to such as
Under the output：
A9.5) if being unsatisfactory for A9.3) in constraints, the positive and negative sequence dq shaft currents reference value of grid side converter according to
Output as described below：
Described step B1) comprise the steps of：
B1.1) during unbalanced grid faults operation, the Voltage Reference instruction of setting machine-side converter is：
In formula, ψsFor permanent magnet flux linkage, LsFor stator reactance, ωsFor permanent magnet direct-drive Wind turbines synchronization angular rate, Kp5、
τi5And Kp6、τi6The respectively proportionality coefficient and integration time constant of dq shaft voltages ring pi regulator and electric current loop pi regulator.
usd, usqIt is the d axles and q shaft voltage reference values of machine-side converter respectively,It is machine-side converter q shaft current reference values,It is straight
Flow busbar voltage reference value, isdAnd isqIt is machine-side converter d axles and q current reference values.
Compared with prior art, the present invention has the advantages that：
The present invention is become by the control to permanent magnet direct-drive Wind turbines machine-side converter and grid side converter taking into full account
On the basis of parallel operation capacity and unit operation operating mode, the positive and negative sequence dq shaft currents of permanent magnet direct-drive Wind turbines grid side converter are obtained
Given instruction so that permanent magnet direct-drive Wind turbines can suppress grid entry point voltage unbalance factor, and be carried to greatest extent to power network
For watt current, so as to significantly enhance low voltage ride-through capability of the permanent magnet direct-drive Wind turbines under unbalanced grid faults and
Its and power network the quality of power supply.
Brief description of the drawings
Fig. 1 is the structural representation that permanent magnet direct-drive Wind turbines access power system.
Fig. 2 is the unbalanced fault traversing control method block diagram of permanent magnet direct-drive Wind turbines of the present invention.
Fig. 3 is the positive and negative sequence current reference value computing module of permanent magnet direct-drive Wind turbines grid side converter of the present invention.
Fig. 4 is not use the present invention when grid entry point voltage unbalance factor is 12% and voltage positive-sequence component drops to 0.9pu
Control method and the simulation waveform using permanent magnet direct-drive Wind turbines under control method of the present invention.
Fig. 5 is not use the present invention when grid entry point voltage unbalance factor is 16% and voltage positive-sequence component drops to 0.85pu
Control method and the simulation waveform using permanent magnet direct-drive Wind turbines under control method of the present invention.
Embodiment
Specific embodiments of the present invention are described in detail below in conjunction with accompanying drawing.
Fig. 1 is the structural representation that permanent magnet direct-drive Wind turbines access power system, and permanent magnet direct-drive Wind turbines pass through public affairs
Concurrent (point ofcommon coupling, PCC) accesses bulk power grid.During unbalanced grid faults, permanent magnet direct-drive Wind turbines
Its grid side converter capacity is made full use of, while grid entry point voltage unbalance factor is ensured a suppression of, to greatest extent to power network
Watt current is provided, to improve permanent magnet direct-drive Wind turbines fault ride-through capacity and and network electric energy quality.
Referring to Fig. 2, the enhancing low voltage crossing controlling party of permanent magnet direct-drive Wind turbines under unbalanced grid faults of the present invention
Method, the control object that it includes have：Direct-current chain electric capacity 1, machine-side converter 2, grid side converter 3, space vector modulation module 4,
Permanent magnet direct-drive Wind turbines 5, voltage sensor 6, current sensor 7, grid side converter forward-order current reference value computing module 8,
Grid side converter negative-sequence current reference value computing module 9, forward-order current maximum amplitude computing module 10, trapper 11 are positive same
Leg speed rotational coordinates shafting is to the invariable power conversion module 12 of the static two-phase α β systems of axis, reverse sync angular speed rotational coordinates
Shafting to the invariable power conversion module 13 of the static two-phase α β systems of axis, to static two-phase α β sit by the static abc three-phases system of axis
The invariable power conversion module 14 of parameter system, permanent work(of the static two-phase α β systems of axis to positive synchronous angular velocity rotational coordinates shafting
Rate conversion module 15, invariable power conversion module of the static two-phase α β systems of axis to reverse sync angular speed rotational coordinates shafting
16, phaselocked loop (PLL) 17.
Specific implementation step of the present invention is as follows：
(A) rate-determining steps of permanent magnet direct-drive Wind turbines grid side converter are：
A1) wind farm grid-connected three-phase voltage signal u is gathered using voltage sensor 6gabcAnd DC bus-bar voltage letter
Number Udc, grid side converter output three-phase current signal i is gathered using current sensor 7gabc；
A2) the permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal u that will be collectedgabcBy digital phase-locked loop
(PLL) the electrical angle θ of wind farm grid-connected positive sequence voltage vector is obtained after 17gWith synchronous angular rate ωe；
A3) by permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal ugabcBy static three-phase abc coordinate systems to quiet
The only invariable power coordinate transformation module 14 of the two-phase α β systems of axis, the voltage signal under the convert to static two-phase α β systems of axis,
That is ugα、ugβ；
A4 permanent magnet direct-drive Wind turbines grid entry point positive sequence voltage d axle oriented approach) is used, by step A3) gained static two
Voltage signal u under the phase α β systems of axisgα、ugβSat through the static two-phase α β systems of axis to positive, reverse sync angular speed rotation
The invariable power conversion module 15,16 of parameter system, then by 2 ωeTrapper 11 filters, and obtains wind farm grid-connected three-phase voltage and exists
Forward direction during being run under the conditions of unbalanced grid faults, the dq axis components under reverse sync angular speed rotational coordinates shafting, i.e.,
A5) the grid side converter three-phase current signal i that will be collectedgabcBy the static three-phase abc systems of axis to static
The invariable power coordinate transformation module 14 of the two-phase α β systems of axis obtains the electric current i under the static two-phase α β systems of axisgα、igβ；
A6) by step A5) grid side converter output current i under the static two-phase α β systems of axis of gainedgα、igβThrough static two
The phase α β systems of axis are to positive, reverse sync angular speed rotational coordinates shafting invariable power conversion module 15,16, then by 2 ωe
Trapper 11 filters, and obtains dq axle point of the grid side converter output current under positive, reverse sync angular speed rotating coordinate system
Amount, i.e.,
A7) by step A4) obtained by permanent magnet direct-drive Wind turbines grid entry point voltage reverse sync angular speed rotate sit
Dq axis components under mark system, i.e.,Grid side converter negative-sequence current reference value computing module 9 is delivered to, according to the following formula,
During can determine that unbalanced grid faults operation, grid side converter can suppress grid entry point voltage unbalance factor to defeated needed for zero
The negative-sequence current reference value without amplitude limit gone out
In formula, Kp1And τi1The respectively proportionality coefficient of negative-sequence current reference value computing module pi regulator and the time of integration
Constant；
A8) by step A4) and A7) obtained by wind farm grid-connected voltage sat in positive, reverse sync angular speed rotation
Dq axis components under mark systemAnd grid side converter negative-sequence current reference value iIt is delivered to net
Side converter forward-order current maximum amplitude computing module 10, according to the following formula, it may be determined that the permanent magnetism direct drive wind under negative-sequence current limitation
Electric system can be output the amplitude of forward-order current：
In formula, | igmax| the maximum current amplitude allowed to flow through for grid side converter；
A9) by step A4) obtain permanent magnet direct-drive Wind turbines grid side converter in reverse sync angular speed rotational coordinates
Dq shaft voltage reference values under systemAnd step A6) and step A8) obtain permanent magnet direct-drive Wind turbines net side become
Dq shaft current reference value of the parallel operation under positive, reverse sync angular speed rotating coordinate systemBecome with net side
Parallel operation allows the maximum current i of operationgmaxThe positive and negative sequence current reference value computing module 8,9 of grid side converter is delivered to (see figure
3) the positive and negative sequence current reference value of grid side converter, is determined
The positive and negative sequence current reference value computing module 8,9 of grid side converter of the present invention, the following institute of specific implementation step
Show：
A9.1) unbalanced grid faults operation during, utilize step A7) obtain the grid side converter negative phase-sequence without amplitude limit
Electric current dq axle reference valuesCalculate grid side converter negative-sequence current reference value amplitudeWith grid side converter positive sequence electricity
Flow reference value amplitude
And carry out following judgement：
In formula,Forward direction synchronous angular velocity rotating coordinate system when realizing maximal wind-power tracking for permanent magnet direct-drive Wind turbines
Lower net side d shaft current positive-sequence components,For not output reactive power when forward direction synchronous angular velocity rotating coordinate system under net side q axles
Electric current positive-sequence component；
A9.2) if meeting A9.1) in constraints, the positive and negative sequence dq shaft current command values of grid side converter are according to such as
Under the output：
In formula,For the output of grid side converter positive and negative sequence current reference value computing module just,
Negative phase-sequence dq shaft current reference values；
A9.3) if being unsatisfactory for A9.1) in constraints, judge permanent magnet direct-drive Wind turbines grid side converter negative phase-sequence electricity
Flow reference value amplitudeWhether the constraints that satisfaction is shown below：
A9.4) if meeting A9.3) in constraints, the positive and negative sequence dq shaft current reference values of grid side converter are according to such as
Under the output：
A9.5) if being unsatisfactory for A9.3) in constraints, the positive and negative sequence dq shaft currents reference value of grid side converter according to
Output as described below：
A10) by step A7) and the grid side converter positive sequence, the negative-sequence current reference value that A9) are calculated be delivered to net respectively
Side converter positive sequence, negative-sequence current inner ring controlling unit, according to the following formula, grid side converter are obtained at positive, reverse sync speed angle
Positive and negative sequence voltage dq axis components under speed rotating coordinate system control
In formula, Kp3And τi3The proportionality coefficient of current inner loop PI controllers respectively in grid side converter positive sequence control system
And integration time constant, Kp4And τi4The proportionality coefficient of electric current loop PI controllers respectively in grid side converter negative phase-sequence control system
And integration time constant, LgFor the inductance of the reactor of parallel-connection network side converter；
A11) by step A10) obtained positive and negative sequence control voltage dq axis components of grid side converter WithPoint
Not Jing Guo positive, reverse sync angular speed rotational coordinates shafting to the static two-phase α β systems of axis invariable power conversion module 12,
13 obtain positive and negative sequence control voltage under the static two-phase α β systems of axis
A12) by step A11) the obtained positive and negative sequence control voltage of grid side converterWith DC bus-bar voltage Udc
Grid side converter PWM drive signal is produced by space vector modulation module 4；To suppress unbalanced source voltage degree；
(B) rate-determining steps of permanent magnet direct-drive wind power system machine-side converter are：
B1) permanent magnet direct-drive wind power system machine-side converter 2 uses vector control strategy, and its control voltage passes through space vector
Pulsewidth modulation produces motor side converter PWM drive signal, with permanent magnet direct-drive wind power system direct current during maintaining unbalanced fault
The stabilization of busbar voltage.Specific implementation step B1) it is as follows：
B1.1) during unbalanced grid faults operation, the Voltage Reference instruction of setting machine-side converter is：
In formula, ψsFor permanent magnet flux linkage, LsFor stator reactance, ωsFor permanent magnet direct-drive Wind turbines synchronization angular rate, Kp5、
τi5And Kp6、τi6The respectively proportionality coefficient and integration time constant of dq shaft voltages ring pi regulator and electric current loop pi regulator.
The present invention realizes permanent magnet direct-drive wind turbine on the premise of hardware device is not set up under unbalanced grid faults
The enhancing low voltage crossing control of group, by making full use of permanent magnet direct-drive Wind turbines grid side converter capacity, farthest
While suppressing grid entry point voltage unbalance factor, and certain active power is provided for power network, permanent magnet direct-drive can be significantly improved
The not off-grid safe and stable operation ability of Wind turbines and its and power network the quality of power supply.
Fig. 4 is that grid entry point voltage unbalance factor reaches 12% and voltage positive-sequence component drops to 0.9pu, wherein 1.5s-2s
Period PMSG wind power system is not using the control strategy of any suppression voltage unbalance factor, and PMSG systems are adopted during 2s-2.5s
With the present invention carry control method effectively by unbalanced source voltage degree from 12% be reduced to 0 and voltage waveform recover symmetrically,
So that grid entry point transient voltage level significantly improves, and now PMSG still realizes maximal wind-power tracking control.Fig. 5 is grid-connected
Point voltage unbalance factor reaches 16% and voltage positive-sequence component drops to 0.85pu, PMSG wind power systems during wherein 1.5s-2s
Not using the control strategy of any suppression voltage unbalance factor, PMSG systems are carried using the present invention during 2s-2.5s failures
Unbalanced source voltage degree still effectively can be reduced to 0 by control method from 16%；But now PMSG can not realize most strong wind again
Energy tracing control, certain active power mean value is exported merely with GSC current margins, while suppressing grid entry point Voltage unbalance
Certain active support is provided for power network, effectively improves the set grid-connection quality of power supply.
It is last it should be noted that the examples detailed above of the present invention is only example to illustrate the invention, and be not
It is the restriction to embodiments of the present invention.Although the present invention is described in detail with reference to preferred embodiment by applicant, right
For those of ordinary skill in the art, can also make on the basis of the above description other it is various forms of change and
Change.Here all embodiments can not be exhaustive.Every belong to that technical scheme amplifies out aobvious and
Row of the change or variation being clear to still in protection scope of the present invention.
Claims (3)
1. permanent magnet direct-drive Wind turbines strengthen low voltage traversing control method under unbalanced grid faults, it is characterised in that：We
Method is related to the control to permanent magnet direct-drive Wind turbines grid side converter and machine-side converter；
(A) rate-determining steps of permanent magnet direct-drive Wind turbines grid side converter are：
A1 permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal u) is gatheredgabc, grid side converter output three-phase current signal
igabcAnd DC bus-bar voltage signal Udc；
A2) the permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal u that will be collectedgabcObtained after digital phase-locked loop PLL
The electrical angle θ of permanent magnet direct-drive Wind turbines grid entry point positive sequence voltage vectorgWith synchronous angular rate ωe；
A3) by permanent magnet direct-drive Wind turbines grid entry point three-phase voltage signal ugabcBy static three-phase abc coordinate systems to static two-phase
The invariable power coordinate transform of the α β systems of axis, the voltage signal under the convert to static two-phase α β systems of axis, i.e. ugα、ugβ；
A4 permanent magnet direct-drive Wind turbines grid entry point positive sequence voltage d axle oriented approach) is used, respectively by step A3) gained static two
Voltage signal u under the phase α β systems of axisgα、ugβSat through the static two-phase α β systems of axis to positive, reverse sync angular speed rotation
The invariable power conversion of parameter system, then by 2 ωeTrapper filters, and obtains permanent magnet direct-drive Wind turbines grid entry point three-phase voltage and exists
Forward direction during being run under the conditions of unbalanced grid faults, the dq axis components under reverse sync angular speed rotational coordinates shafting, i.e.,
A5) the grid side converter three-phase current signal i that will be collectedgabcBy the static three-phase abc systems of axis to static two-phase α β
The invariable power coordinate transform of the system of axis obtains the output current i under the static two-phase α β systems of axisgα、igβ；
A6) by step A5) grid side converter output current i under the static two-phase α β systems of axis of gainedgα、igβSat through static two-phase α β
Parameter system converts to positive, reverse sync angular speed rotational coordinates shafting invariable power, then by 2 ωeTrapper filters, and obtains
Dq axis component of the grid side converter output current under positive, reverse sync angular speed rotating coordinate system, i.e.,
A7) by step A4) obtained by permanent magnet direct-drive Wind turbines grid entry point voltage in reverse sync angular speed rotating coordinate system
Under dq axis components, i.e.,Grid side converter negative-sequence current reference value computing module is delivered to, determines electricity according to the following formula
During net unbalanced fault is run, grid side converter grid entry point voltage unbalance factor can be suppressed to output needed for zero without
The negative-sequence current reference value of amplitude limit
In formula, Kp1And τi1The respectively proportionality coefficient and integration time constant of negative-sequence current reference value computing module pi regulator；
A8) by step A4) the dq axles of obtained wind farm grid-connected voltage under positive, reverse sync angular speed rotating coordinate system
ComponentAnd step A7) obtained negative-sequence current reference value of the grid side converter without amplitude limitGrid side converter forward-order current maximum amplitude computing module is delivered to, according to the following formula, is determined under negative-sequence current limitation
Permanent magnet direct-drive wind power system can be output the amplitude of forward-order current：
In formula, | igmax| the maximum current amplitude allowed to flow through for grid side converter；
A9) by step A4) obtain permanent magnet direct-drive Wind turbines grid side converter under reverse sync angular speed rotating coordinate system
Dq shaft voltage componentsAnd step A6) and step A8) obtain permanent magnet direct-drive Wind turbines grid side converter exist
Dq shaft current components under positive, reverse sync angular speed rotating coordinate systemAllow with grid side converter
The maximum current i of operationgmaxBe delivered to the positive and negative sequence current reference value computing module of grid side converter, determine grid side converter just,
Negative-sequence current reference value
A10) by step A9) the grid side converter positive sequence, the negative-sequence current reference value that are calculated be delivered to grid side converter respectively
Positive sequence, negative-sequence current inner ring controlling unit, according to the following formula, grid side converter are obtained in positive, reverse sync speed angular speed rotation
Positive and negative sequence control voltage dq axis components under coordinate system control
In formula, Kp3And τi3The proportionality coefficient and integration of current inner loop PI controllers respectively in grid side converter positive sequence control system
Time constant, Kp4And τi4The proportionality coefficient and integration of electric current loop PI controllers respectively in grid side converter negative phase-sequence control system
Time constant, LgFor the inductance of the reactor of grid side converter；
A11) by step A10) obtained positive and negative sequence control voltage dq axis components of grid side converter WithPass through respectively
The positive, invariable power of reverse sync angular speed rotational coordinates shafting to the static two-phase α β systems of axis is crossed to convert to obtain static two-phase
Positive and negative sequence control voltage under the α β systems of axis
A12) by step A11) the obtained positive and negative sequence control voltage of grid side converterWith DC bus-bar voltage UdcPass through
Space vector modulation produces grid side converter PWM drive signal, to suppress unbalanced source voltage degree；
(B) rate-determining steps of permanent magnet direct-drive Wind turbines machine-side converter are：
B1) permanent magnet direct-drive Wind turbines machine-side converter uses vector control strategy, and its control voltage passes through space vector pulse width
Modulation produces machine-side converter PWM drive signal, with permanent magnet direct-drive Wind turbines dc bus electricity during maintaining unbalanced fault
The stabilization of pressure.
2. permanent magnet direct-drive Wind turbines strengthen low voltage crossing controlling party under unbalanced grid faults according to claim 1
Method, it is characterised in that described step A9) comprise the steps of：
A9.1) unbalanced grid faults operation during, utilize step A7) obtain the grid side converter negative-sequence current without amplitude limit
Dq axle reference valuesCalculate grid side converter negative-sequence current reference value amplitudeJoin with grid side converter forward-order current
Examine value amplitude
And carry out following judgement：
In formula,Net side under forward direction synchronous angular velocity rotating coordinate system when realizing maximal wind-power tracking for permanent magnet direct-drive Wind turbines
D shaft current positive-sequence components,For not output reactive power when forward direction synchronous angular velocity rotating coordinate system under net side q shaft currents just
Order components；
A9.2) if meeting A9.1) in constraints, the positive and negative sequence dq shaft currents reference value of grid side converter is according to following institute
State output：
In formula,For the positive and negative sequence of the positive and negative sequence current reference value computing module output of grid side converter
Dq shaft current reference values；
A9.3) if being unsatisfactory for A9.1) in constraints, judgment step A9.1) obtain permanent magnet direct-drive Wind turbines net side
Converter negative-sequence current reference value amplitudeWhether the constraints that satisfaction is shown below：
A9.4) if meeting A9.3) in constraints, the positive and negative sequence dq shaft currents reference value of grid side converter is according to following institute
State output：
A9.5) if being unsatisfactory for A9.3) in constraints, the positive and negative sequence dq shaft current reference values of grid side converter are according to as follows
The output：
。
3. permanent magnet direct-drive Wind turbines strengthen low voltage crossing controlling party under unbalanced grid faults according to claim 1
Method, it is characterised in that described step B1) comprise the steps of：
B1.1) during unbalanced grid faults operation, the Voltage Reference instruction of setting machine-side converter is：
In formula, ψsFor permanent magnet flux linkage, LsFor stator reactance, ωsFor permanent magnet direct-drive Wind turbines synchronization angular rate, Kp5、τi5With
Kp6、τi6The respectively proportionality coefficient and integration time constant of dq shaft voltages ring pi regulator and electric current loop pi regulator.usd, usq
It is the d axles and q shaft voltage reference values of machine-side converter respectively,It is machine-side converter q shaft current reference values,It is dc bus
Voltage reference value, isdAnd isqIt is machine-side converter d axles and q current reference values.
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| CN116937499B (en) * | 2023-09-06 | 2024-02-09 | 南方电网调峰调频发电有限公司储能科研院 | Method and device for protecting rotor open-phase unbalance fault of variable speed pumping and accumulating unit |
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