CN112653342B - Complex vector current loop decoupling control device and method under static coordinate system - Google Patents

Complex vector current loop decoupling control device and method under static coordinate system Download PDF

Info

Publication number
CN112653342B
CN112653342B CN202110065647.2A CN202110065647A CN112653342B CN 112653342 B CN112653342 B CN 112653342B CN 202110065647 A CN202110065647 A CN 202110065647A CN 112653342 B CN112653342 B CN 112653342B
Authority
CN
China
Prior art keywords
coordinate system
current
voltage
alpha
under
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110065647.2A
Other languages
Chinese (zh)
Other versions
CN112653342A (en
Inventor
吕建国
刘蕊
解艳宇
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nanjing University of Science and Technology
Original Assignee
Nanjing University of Science and Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nanjing University of Science and Technology filed Critical Nanjing University of Science and Technology
Priority to CN202110065647.2A priority Critical patent/CN112653342B/en
Publication of CN112653342A publication Critical patent/CN112653342A/en
Application granted granted Critical
Publication of CN112653342B publication Critical patent/CN112653342B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

The invention discloses a device and a method for decoupling control of a current loop of a complex vector under a static coordinate system. The device comprises a VIENNA rectifier, a digital processing control module and a driving circuit, wherein the digital processing control module comprises a sampling unit, a voltage control unit, a reference current calculation unit, a complex vector current control unit and a sine pulse width modulation unit. The method comprises the following steps: the sampling unit respectively collects the voltage of upper and lower capacitors at the DC side of the VIENNA rectifier and the three-phase current and voltage at the AC side; the collected direct-current side upper and lower capacitor voltage passes through a voltage control unit and a reference current generation unit to obtain a reference current signal under a static coordinate system; a reference current signal passes through a current loop decoupling control unit to obtain a three-phase fundamental wave modulation signal; the three-phase fundamental wave modulation signal is processed by the sine pulse width modulation unit to obtain a pulse width modulation signal, and the pulse width modulation signal controls the working state of each switching tube of the VIENNA rectifier through a driving circuit. The invention can effectively reduce the coupling between powers and improve the dynamic performance of the system.

Description

Complex vector current loop decoupling control device and method under static coordinate system
Technical Field
The invention belongs to the technical field of control in power electronic transformation technology, and particularly relates to a complex vector current loop decoupling control device and method under a static coordinate system.
Background
The VIENNA rectifier is a three-level topology, and has the biggest characteristics of small quantity of switching devices, low voltage stress borne by a switching tube, low input current harmonic distortion rate, high power density, high reliability, no need of setting driving dead time and the like, and is widely applied to medium-high voltage high-power level electric energy conversion occasions. However, when the rectifier operates at medium and high power, large power loss is generated, so that the switching frequency needs to be reduced to increase the output power of the system. However, the problem of coupling aggravation of the rectifier control system can occur while the switching frequency of the power device is reduced. For the problem of coupling of a control system, related decoupling current control technologies such as feedforward decoupling, feedback decoupling, internal model decoupling, deviation decoupling, complex vector decoupling and the like are widely concerned, however, under the condition of low switching frequency, the coupling of the control system is intensified under the influence of digital control delay, and the decoupling methods can reduce cross coupling but cannot completely offset.
Aiming at the decoupling problem of the VIENNA rectifier under low switching frequency, at present, research of many scholars mainly focuses on decoupling control on the rectifier by adopting a PI controller under the condition of a balanced power grid, but the decoupling control under the balanced power grid fails when the voltage of the power grid is unbalanced, so that the current loop decoupling is incomplete, and the stability of a system is influenced.
Disclosure of Invention
The invention aims to provide a complex vector current loop decoupling control device and method under a static coordinate system, so as to realize the decoupling of a system under an unbalanced power grid and effectively improve the dynamic regulation performance of a VIENNA rectifier.
The technical solution for realizing the purpose of the invention is as follows: a complex vector current loop decoupling control device under a static coordinate system comprises a VIENNA rectifier, a digital processing control module and a driving circuit, wherein the digital processing control module comprises a sampling unit, a voltage control unit, a reference current calculation unit, a complex vector current control unit and a sine pulse width modulation unit;
the sampling unit respectively collects voltage signals of an upper capacitor and a lower capacitor on the direct current side of the VIENNA rectifier, three-phase voltage signals on the alternating current side of the VIENNA rectifier and three-phase current signals on the alternating current side of the VIENNA rectifier;
the voltage control unit processes the voltage signals of the upper capacitor and the lower capacitor on the direct current side into active power reference signals;
the reference current calculation unit processes the active power reference signal and the voltage and current signals obtained after coordinate transformation into a current reference signal under a static coordinate system;
the complex vector current control unit processes the current reference signal to obtain a modulated wave signal, and the modulated wave signal is sent to the sine pulse width modulation unit;
the output end of the sine pulse width modulation unit is connected to each switching tube of each phase bridge arm in the three-level VIENNA rectifier through the driving circuit.
Preferably, the digital processing control modules are chips of TMS320F28377D and EPM 1270T.
A complex vector current loop decoupling control method under a static coordinate system comprises the following steps:
step 1, in each switching period, a sampling unit of a digital control module respectively collects three-phase voltage e at an alternating current sidea、eb、 ecAlternating side three-phase current ia、ib、icOn the DC sideCapacitance voltage UC1And the capacitor voltage U under the DC sideC2；
Step 2, according to the signals collected in the step 1, converting alternating-current side voltage and alternating-current side current in a static abc coordinate system into a static alpha beta coordinate system through Clark, comparing direct-current side capacitor voltage with a voltage reference signal, obtaining an error signal through proportional-integral adjustment, and multiplying the error signal by the voltage reference signal to obtain an active power reference signal;
step 3, extracting a power grid voltage characteristic value according to the obtained active power reference signal, and calculating reference current to obtain reference current i under an alpha beta coordinate system* α、i* β；
Step 4, according to the switching frequency f of the three-level VIENNA rectifiersDetermining the delay time tau of a systemdComprises the following steps:
Figure BSA0000231075050000021
step 5, determining a complex vector decoupling loop according to the calculated delay time, and verifying the effectiveness of the complex vector current controller through the coupling coefficient analysis of the system;
step 6, converting the obtained current iα、iβComparing with reference current, and obtaining a three-phase modulation signal u through a complex vector decoupling loop and Clark inverse transformationa、ub、uc；
And 7, generating a pulse width modulation signal by the three-phase modulation signal through a sine pulse width modulation unit, and controlling the work of a VIENNA rectifier switching tube through a driving circuit.
Further, in step 3, according to the active power reference signal, a grid voltage characteristic value is extracted and reference current calculation is performed to obtain reference current i in an alpha beta coordinate system* α、i* βThe method comprises the following steps:
non-ideal grid voltage ea(t)、eb(t)、ec(t) can be decomposed into positive sequencesComponent and negative sequence component, the expression under the abc coordinate system is:
Figure BSA0000231075050000022
wherein subscripts a, b, c represent a phase a, b phase, c phase; superscript +, -respectively represents positive sequence component and negative sequence component;
Figure BSA0000231075050000023
representing the magnitude of the positive sequence component,
Figure BSA0000231075050000024
representing the magnitude of the negative sequence component; omega is the fundamental angular frequency of the grid voltage;
the network side voltage e under an alpha beta coordinate system can be obtained through Clark transformationα(t)、eβ(t) is:
Figure BSA0000231075050000025
wherein,
Figure BSA0000231075050000026
represents the magnitude of the positive sequence component in the alpha beta coordinate system,
Figure BSA0000231075050000027
representing the magnitude of the negative sequence component in the α β coordinate system.
According to the nature of the Clark transformation,
Figure BSA0000231075050000028
rotates counterclockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system,
Figure BSA0000231075050000029
clockwise at an angular velocity ω relative to the α axis in the α β coordinate system;
Figure BSA0000231075050000031
is stationary relative to the fundamental positive-sequence rotational coordinate system,
Figure BSA0000231075050000032
relative rest with the fundamental frequency negative sequence rotating coordinate system;
the fundamental frequency positive sequence rotation coordinate system rotates anticlockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system; the fundamental frequency negative sequence rotating coordinate system rotates clockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system;
defining: characteristic value of network voltage
Figure BSA0000231075050000033
Are respectively as
Figure BSA0000231075050000034
Projections on a d axis and a q axis in a fundamental frequency positive sequence rotating coordinate system; characteristic value of network voltage
Figure BSA0000231075050000035
Are respectively as
Figure BSA0000231075050000036
Projections on a d axis and a q axis in a fundamental frequency negative sequence rotating coordinate system;
similarly, the current characteristic value can be obtained through the steps
Figure BSA0000231075050000037
According to the instantaneous reactive power theory, the complex power s (t) can be expressed as:
Figure BSA0000231075050000038
wherein j is a complex number unit, p (t) is instantaneous active power, q (t) is instantaneous reactive power, eα、eβRespectively three-phase network voltage ea、eb、ecAlpha-axis component, beta-axis component, i after Clark transformationa、iβAre respectively three-phase currents ia、ib、icAlpha-axis component and beta-axis component after Clark transformation;
three-phase voltage and current are represented as direct current quantities under a two-phase dq rotating coordinate system, the derivation process of reference current can be effectively simplified, and the network-access instantaneous active power p (t) and the network-access instantaneous reactive power q (t) can be obtained according to the formula:
Figure BSA0000231075050000039
in the formula, pc2(t)、ps2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous active power; p is a radical of formula0(t) is the dc component in the net-entry instantaneous active power; q. q.sc2(t)、qs2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous reactive power; q. q of0(t) is the dc component in the network-entry instantaneous reactive power;
the specific expressions are respectively as follows:
Figure BSA00002310750500000310
when the coordinate system is changed back to the α β coordinate system, the expression is:
Figure BSA0000231075050000041
wherein
Figure BSA0000231075050000042
After integration, it can be expressed in matrix form as:
Figure BSA0000231075050000043
inverse solution matrix equation, by which reference current can be obtained under different control targets
Figure BSA0000231075050000044
And introducing a coefficient k into the reference current expression, the reference current expression can be simplified as follows:
Figure BSA0000231075050000045
wherein
Figure BSA0000231075050000046
Different controls are realized mainly by changing the k value in the control process: when k is equal to-1, constant active power control is mainly used for eliminating secondary fluctuation of active power; when k is 0, the negative sequence current is restrained, and the output three-phase current is balanced; when k is 1, the constant reactive power control mainly eliminates the secondary fluctuation of the reactive power.
Further, in step 5, the complex vector decoupling loop is determined according to the calculated delay time, which is specifically as follows:
the delay time brought by signal sampling and PWM inertia link is taudGenerally, the following are selected:
Figure BSA0000231075050000047
wherein, fsFor the switching frequency, as the switching frequency decreases, the corresponding delay time will increase.
Positive sequence vector under alpha and beta coordinate system under time domain
Figure BSA0000231075050000051
And positive sequence vector under dq coordinate system
Figure BSA0000231075050000052
The following relationships exist:
Figure BSA0000231075050000053
according to the determined delay time taudThe positive sequence delay link under the dq coordinate system can be obtained as
Figure BSA0000231075050000054
The time delay link is converted into an alpha beta coordinate system to obtain
Figure BSA0000231075050000055
According to delay time taudThe positive sequence time delay link under the dq coordinate system can be obtained
Figure BSA0000231075050000056
Comprises the following steps:
Figure BSA0000231075050000057
then the negative sequence time delay link under the corresponding dq coordinate system
Figure BSA0000231075050000058
Comprises the following steps:
Figure BSA0000231075050000059
where ω is the grid voltage fundamental angular frequency.
Converting the delay link to alpha-beta coordinate system to obtain Gαβ_d(s) is;
Figure BSA00002310750500000510
adding a controlled object G 'after a delay link'VIENNA_αβ(s) is expressed as:
Figure BSA00002310750500000511
the delay link also influences the coupling between the active power and the reactive power of the system when the voltage of the power grid is unbalanced, and the coupling degree between the active power and the reactive power is more serious along with the reduction of the switching frequency.
According to the delay link of the VIENNA rectifier, a positive sequence delay compensation link can be assumed
Figure BSA00002310750500000512
The expression of (a) is:
Figure BSA00002310750500000513
wherein
Figure BSA00002310750500000514
To delay the compensation angle, there are now:
Figure BSA00002310750500000515
knowing the positive sequence s ═ j ω, the delay compensation angle can be calculated
Figure BSA00002310750500000516
The positive sequence delay compensation procedure is
Figure BSA00002310750500000517
The negative sequence delay compensation link can be obtained by the same way
Figure BSA00002310750500000518
For convenience of calculation, the delay compensation link is usually subjected to euler transform:
Figure BSA00002310750500000519
considering VIENN at low switching frequencyWhen the A rectifier is modeled in an alpha beta coordinate system, although the current iaAnd iβThere is no coupling between the two, but there is still coupling inside the system, and this coupling cannot be eliminated by the traditional proportional resonant controller, so a reduced-order resonant controller is designed to realize decoupling inside the system.
According to the relation between the positive sequence vectors in the alpha beta coordinate system and the dq coordinate system, the positive sequence complex vector decoupling controller in the alpha beta coordinate system can be deduced
Figure BSA00002310750500000520
Is composed of
Figure BSA00002310750500000521
Negative sequence complex vector decoupling controller obtained by same method
Figure BSA0000231075050000061
Comprises the following steps:
Figure BSA0000231075050000062
wherein k ispIs a proportionality coefficient, kiIs the resonance coefficient, krIs the resonance coefficient.
In order to realize the simultaneous control of positive and negative sequence components under an alpha-beta coordinate system in a non-ideal power grid and avoid current i under the alpha-beta coordinate systemaAnd iβThe positive and negative sequence separation link can obtain the complex vector current controller G added with the delay compensationαβ(s) is
Figure BSA0000231075050000063
Further, step 5 deduces a coupling coefficient relationship under the non-ideal grid condition, and the coupling analysis between the active power and the reactive power can be visually represented to verify the effectiveness of the complex vector current controller, and the specific results are as follows:
the current loop closed loop transfer function G(s) without considering the grid voltage disturbance is as follows:
Figure BSA0000231075050000064
wherein G isVIENNA_αβ(s) a VIENNA rectifier object transfer function in an α β coordinate system; gαβ(s) is the current controller transfer function; re(s) is the real component of the current loop closed loop transfer function; im(s) is the imaginary component of the current loop closed loop transfer function.
The current feedback value i under the alpha beta coordinate system can be obtained according to the formulaα(s)、iβThe relationship between(s) is:
Figure BSA0000231075050000065
Figure BSA0000231075050000066
if the active power command and the reactive power command change according to the step response, and u (t) is the step response change, the active power command p0(t) pu (t), reference reactive power q0(t) qu (t). According to a reference current calculation formula, the alpha and beta axis reference current under the time domain can be obtained
Figure BSA0000231075050000067
Is composed of
Figure BSA0000231075050000068
Figure BSA0000231075050000069
Alpha-beta axis reference current under frequency domain can be obtained by Laplace transformation
Figure BSA00002310750500000610
Is composed of
Figure BSA0000231075050000071
Figure BSA0000231075050000072
Substituting the current feedback value i into the alpha beta coordinate systemα(s)、iβ(s) availability
Figure BSA0000231075050000073
Figure BSA0000231075050000074
Wherein
Figure BSA0000231075050000075
Figure BSA0000231075050000076
Figure BSA0000231075050000077
Figure BSA0000231075050000078
Transforming the reverse Laplace to time domain to obtain A (t), B (t), C (t), D (t), and current feedback value i of alpha-beta coordinate system in time domainα(t)、iβ(t)：
Figure BSA0000231075050000079
Figure BSA00002310750500000710
The instantaneous complex power calculation formula of claim 4 is used to obtain the expressions of instantaneous active power p (t) and reactive power q (t), which are respectively
Figure BSA00002310750500000711
Figure BSA00002310750500000712
Substituting the current feedback value and the positive and negative sequence voltages under the corresponding alpha and beta coordinate systems to obtain
Figure BSA0000231075050000081
Figure BSA0000231075050000082
Coefficient of coupling H1、H2Are respectively as
Figure BSA0000231075050000083
Figure BSA0000231075050000084
Introducing an unbalance concept, defining the unbalance lambda as the ratio of the negative sequence component amplitude to the positive sequence component amplitude, and obtaining a simplified coupling coefficient expression as follows:
Figure BSA0000231075050000085
Figure BSA0000231075050000086
compared with the prior art, the invention has the remarkable advantages that: (1) the control is carried out under a static reference coordinate system, so that the calculation complexity and unnecessary time delay and errors are reduced; (2) the coupling between active power and reactive power under the non-ideal power grid condition can be effectively improved, the dynamic performance of the system is improved, and the control system is simple and easy to realize.
Drawings
Fig. 1 is a schematic structural diagram of a complex vector current loop decoupling control system based on a static coordinate system.
FIG. 2 is a control block diagram of a complex vector current loop decoupling control system based on a static coordinate system.
Fig. 3 is a schematic diagram of a main circuit structure of the VIENNA rectifier.
Fig. 4 is a schematic diagram of the coupling coefficient without considering the system delay by using the conventional proportional resonance control and the decoupling control method of the present invention in the embodiment of the present invention. Wherein (a) adopts the traditional proportional resonance to control the coupling coefficient H1The (b) is the control of the coupling coefficient H by using the traditional proportional resonance2The (c) is a coupling coefficient H adopting the decoupling control method of the invention1The (d) is a coupling coefficient H adopting the decoupling control method of the invention2Schematic representation.
Fig. 5 is a schematic diagram of a coupling coefficient considering system delay by using a conventional proportional resonance control and the decoupling control method of the present invention in the embodiment of the present invention. Wherein (a) is coupling coefficient H of conventional proportional resonant controller1The (b) is the coupling coefficient H of the traditional proportional resonant controller2The schematic diagram is shown in (c) is a coupling coefficient H adopting the decoupling control method of the invention1Schematic diagram, (d) is a decoupling control adopting the inventionCoupling coefficient of the manufacturing method H2Schematic illustration.
FIG. 6 is a waveform of three-phase AC voltage, three-phase AC current, DC side voltage and power under grid-connected condition of the VIENNA rectifier, wherein (a) is a waveform of three-phase AC voltage, three-phase AC current, DC side voltage and power at a switching frequency of 5kHz after the method of the present invention is used; (b) waveform diagrams of three-phase alternating voltage, three-phase alternating current, direct-side voltage and power at a switching frequency of 2.5kHz after the method of the present invention is used.
Fig. 7 is a waveform diagram of three-phase ac voltage, three-phase ac current, dc-side voltage, active power and reactive power at a switching frequency of 5kHz before and after the use of the method of the present invention, wherein (a) is a waveform diagram of three-phase ac voltage, three-phase ac current, dc-side voltage, active power and reactive power before the use of the control method of the present invention; (b) the waveform diagrams of three-phase alternating voltage, three-phase alternating current, direct-current side voltage, active power and reactive power after the control method of the invention is used.
Fig. 8 is a waveform diagram of three-phase alternating voltage, three-phase alternating current, direct-current side voltage, active power, and reactive power at a switching frequency of 2.5kHz before and after the use of the method of the present invention, in which (a) is a waveform diagram of three-phase alternating voltage, three-phase alternating current, direct-current side voltage, active power, and reactive power before the use of the control method of the present invention; (b) the waveform diagrams of the three-phase alternating voltage, the three-phase alternating current, the direct-current side voltage, the active power and the reactive power after the control method of the invention is used are shown.
Detailed Description
The invention is described in further detail below with reference to the figures and the embodiments.
With reference to fig. 1, the complex vector current loop decoupling control device based on the stationary coordinate system of the present invention includes a VIENNA rectifier, a digital processing control module and a driving circuit, wherein the digital processing control module includes a sampling unit, a voltage control unit, a reference current calculation unit, a complex vector current control unit and a sinusoidal pulse width modulation unit.
The system comprises a sampling unit, a reference current generating unit, a complex vector current decoupling control unit, a VIENNA rectifier, a transformer and a transformer, wherein the VIENNA rectifier is connected with the VIENNA rectifier; sampling the obtained voltage signals of the upper capacitor and the lower capacitor on the direct current side, and obtaining an active power reference signal through a voltage control unit; the active power reference signal and the voltage and current signals obtained after coordinate transformation are processed by a reference current generation unit under a static coordinate system to obtain a current reference signal under the static coordinate system; the complex vector current decoupling control unit processes the current reference signal to obtain a modulated wave signal, and sends the modulated wave signal to the sinusoidal pulse width modulation unit, and the output end of the sinusoidal pulse width modulation unit is connected to each switching tube of each phase bridge arm in the three-level VIENNA rectifier through a driving circuit; the digital processing control module adopts TMS320F2808 and EPM1270T chips.
A complex vector current loop decoupling control method under a static coordinate system comprises the following steps:
step 1, in each switching period, a sampling unit collects three-phase voltage e at an alternating current sidea、eb、ecAlternating side three-phase current ia、ib、icTransforming the alpha-beta-phase coordinate system to a static alpha-beta coordinate system through Clark transformation;
step 2, sampling capacitor voltage U on the direct current sideC1And the capacitor voltage U under the DC sideC2Comparing the active power reference signal with a voltage reference signal, obtaining an error signal through proportional-integral regulation, and multiplying the error signal by the voltage reference signal to obtain an active power reference signal;
the transfer function of the voltage loop PI controller is:
Figure BSA0000231075050000101
wherein k isupIs a proportionality coefficient, kuiIs an integral coefficient;
combination drawing2, active power reference signal P*The expression is as follows:
Figure BSA0000231075050000102
wherein, UdcIs the sum of the capacitor voltages on the dc side,
Figure BSA0000231075050000103
is a DC side reference voltage;
step 3, extracting a power grid voltage characteristic value according to the obtained active power reference signal, and calculating reference current to obtain reference current i under an alpha beta coordinate system* α、i* β；
Non-ideal grid voltage ea(t)、eb(t)、ec(t) can be decomposed into positive and negative sequence components, and the expression under the abc coordinate system is:
Figure BSA0000231075050000104
wherein subscripts a, b, c represent phases a, b, c; superscript +, -represents positive sequence component and negative sequence component, respectively;
Figure BSA0000231075050000105
representing the magnitude of the positive sequence component,
Figure BSA0000231075050000106
representing the magnitude of the negative sequence component; omega is the fundamental angular frequency of the grid voltage;
the network side voltage e under the alpha beta coordinate system can be obtained through Clark transformationα(t)、eβ(t) is:
Figure BSA0000231075050000107
wherein,
Figure BSA0000231075050000108
represents the magnitude of the positive sequence component in the alpha beta coordinate system,
Figure BSA0000231075050000109
the amplitude of the negative sequence component in the α β coordinate system is represented.
According to the nature of the Clark transformation,
Figure BSA00002310750500001010
rotates counterclockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system,
Figure BSA00002310750500001011
clockwise at an angular velocity ω relative to the α axis in the α β coordinate system;
Figure BSA00002310750500001012
is stationary relative to the fundamental positive-sequence rotational coordinate system,
Figure BSA00002310750500001013
relative rest with the fundamental frequency negative sequence rotating coordinate system;
the fundamental frequency positive sequence rotation coordinate system rotates anticlockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system; the fundamental frequency negative sequence rotating coordinate system rotates clockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system;
defining: characteristic value of network voltage
Figure BSA00002310750500001014
Are respectively as
Figure BSA00002310750500001015
Projection on d axis and q axis in fundamental frequency positive sequence rotation coordinate system;
characteristic value of network voltage
Figure BSA0000231075050000111
Are respectively as
Figure BSA0000231075050000112
Projections on a d axis and a q axis in a fundamental frequency negative sequence rotation coordinate system;
the current characteristic value can be obtained in the same way
Figure BSA0000231075050000113
According to the instantaneous reactive power theory, the complex power s (t) can be expressed as:
Figure BSA0000231075050000114
wherein j is a complex number unit, p (t) is instantaneous active power, q (t) is instantaneous reactive power, eα、eβRespectively three-phase network voltage ea、eb、ecAlpha-axis component, beta-axis component, i after Clark transformationa、iβAre respectively three-phase currents ia、ib、icAlpha-axis component and beta-axis component after Clark transformation;
three-phase voltage and current are represented as direct current quantities under a two-phase dq rotating coordinate system, the derivation process of reference current can be effectively simplified, and the network-access instantaneous active power p (t) and the network-access instantaneous reactive power q (t) can be obtained according to the formula:
Figure BSA0000231075050000115
in the formula, pc2(t)、ps2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous active power; p is a radical of0(t) is the dc component in the net-entry instantaneous active power; q. q.sc2(t)、qs2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous reactive power; q. q.s0(t) is the dc component in the network-entry instantaneous reactive power;
the specific expressions are respectively as follows:
Figure BSA0000231075050000116
when the coordinate system is changed back to the α β coordinate system, the expression is:
Figure BSA0000231075050000117
wherein
Figure BSA0000231075050000118
After integration, it can be represented in matrix form as:
Figure BSA0000231075050000121
inverse solution matrix equation, by which reference current can be obtained under different control targets
Figure BSA0000231075050000122
And introducing a coefficient k into the reference current expression, the reference current expression can be simplified as follows:
Figure BSA0000231075050000123
wherein
Figure BSA0000231075050000124
Different controls are realized mainly by changing the k value in the control process: when k is equal to-1, constant active power control is mainly used for eliminating secondary fluctuation of active power; when k is 0, the negative sequence current is restrained, and the output three-phase current is balanced; when k is 1, the constant reactive power control mainly eliminates the secondary fluctuation of the reactive power.
Step 4, according to the switching frequency f of the three-level VIENNA rectifiersDetermining the delay time tau of a systemdComprises the following steps:
Figure BSA0000231075050000125
step 5, determining a complex vector decoupling loop according to the calculated delay time, and verifying the effectiveness of the complex vector current controller through the coupling coefficient analysis of the system;
positive sequence vector under alpha and beta coordinate system under time domain
Figure BSA0000231075050000126
And a positive sequence vector in dq coordinate system
Figure BSA0000231075050000127
The following relationships exist:
Figure BSA0000231075050000128
according to the determined delay time taudThe positive sequence delay link under the dq coordinate system can be obtained as
Figure BSA0000231075050000129
The time delay link is converted into an alpha beta coordinate system to obtain
Figure BSA00002310750500001210
According to delay time taudThe positive sequence time delay link under the dq coordinate system can be obtained
Figure BSA00002310750500001211
Comprises the following steps:
Figure BSA00002310750500001212
then the negative sequence time delay link under the corresponding dq coordinate system
Figure BSA00002310750500001213
Comprises the following steps:
Figure BSA00002310750500001214
where ω is the grid voltage fundamental angular frequency.
Converting the delay link to alpha-beta coordinate system to obtain Gαβ_d(s) is;
Figure BSA0000231075050000131
adding a controlled object G 'after a delay link'VIENNA_αβ(s) is expressed as:
Figure BSA0000231075050000132
the delay link also influences the coupling between the active power and the reactive power of the system when the voltage of the power grid is unbalanced, and the coupling degree between the active power and the reactive power is more serious along with the reduction of the switching frequency.
According to the delay link of the VIENNA rectifier, a positive sequence delay compensation link can be assumed
Figure BSA0000231075050000133
The expression of (a) is:
Figure BSA0000231075050000134
wherein
Figure BSA0000231075050000135
To delay compensate the angle, there are now:
Figure BSA0000231075050000136
knowing the positive sequence time s ═ j ω, we can calculate the delay at this timeTime compensation angle
Figure BSA0000231075050000137
The positive sequence delay compensation procedure is
Figure BSA0000231075050000138
The negative sequence delay compensation link can be obtained by the same way
Figure BSA0000231075050000139
For convenience of calculation, the delay compensation link is usually subjected to euler transform:
Figure BSA00002310750500001310
considering that the VIENNA rectifier is modeled in the alpha beta coordinate system under the condition of low switching frequency, although the current iaAnd iβThere is no coupling between the two, but there is still coupling inside the system, and this coupling cannot be eliminated by the traditional proportional resonant controller, so a reduced-order resonant controller is designed to realize decoupling inside the system.
According to the relation between the positive sequence vector under the alpha beta coordinate system and the positive sequence vector under the dq coordinate system in the time domain, the positive sequence complex vector decoupling controller under the alpha beta coordinate system can be deduced
Figure BSA00002310750500001311
Is composed of
Figure BSA00002310750500001312
Negative sequence complex vector decoupling controller obtained by same method
Figure BSA00002310750500001313
Comprises the following steps:
Figure BSA00002310750500001314
wherein k ispIs a proportionality coefficient, kiIs the resonance coefficient, krIs the resonance coefficient.
In order to realize the simultaneous control of positive and negative sequence components under an alpha-beta coordinate system in a non-ideal power grid and avoid current i under the alpha-beta coordinate systemaAnd iβThe positive and negative sequence separation link can obtain the complex vector current controller G added with the delay compensationαβ(s) is
Figure BSA00002310750500001315
The control block diagram of the complex vector current controller is shown in fig. 3.
The current loop closed loop transfer function G(s) without considering the grid voltage disturbance is as follows:
Figure BSA0000231075050000141
wherein G isVIENNA_αβ(s) is a VIENNA rectifier object transfer function in an alpha beta coordinate system; gαβ(s) is the current controller transfer function; re(s) is the real component of the current loop closed loop transfer function; im(s) is the imaginary component of the current loop closed loop transfer function.
The current feedback value i under the alpha beta coordinate system can be obtained according to the formulaα(s)、iβThe relationship between(s) is:
Figure BSA0000231075050000142
Figure BSA0000231075050000143
if the active power command and the reactive power command change according to the step response, and u (t) is set as the step response change, the active power command p0(t) pu (t), reference reactive power q0(t) qu (t). According to a reference current calculation formula, obtainingReference current of alpha-beta axis under time domain
Figure BSA0000231075050000144
Is composed of
Figure BSA0000231075050000145
Figure BSA0000231075050000146
Alpha-beta axis reference current under frequency domain can be obtained by Laplace transformation
Figure BSA0000231075050000147
Is composed of
Figure BSA0000231075050000148
Figure BSA0000231075050000149
Substituting the current feedback value i into the alpha beta coordinate systemα(s)、iβ(s) availability
Figure BSA00002310750500001410
Figure BSA00002310750500001411
Wherein
Figure BSA0000231075050000151
Figure BSA0000231075050000152
Figure BSA0000231075050000153
Figure BSA0000231075050000154
Transforming the reverse Laplace to time domain to obtain A (t), B (t), C (t), D (t), and current feedback value i of alpha-beta coordinate system in time domainα(t)、iβ(t)：
Figure BSA0000231075050000155
Figure BSA0000231075050000156
According to the calculation formula of the instantaneous complex power, the expressions of the instantaneous active power p (t) and the reactive power q (t) can be obtained, wherein the expressions are respectively
Figure BSA0000231075050000157
Figure BSA0000231075050000158
Substituting the current feedback value and the positive and negative sequence voltages under the corresponding alpha and beta coordinate system to obtain the current feedback value
Figure BSA0000231075050000159
Figure BSA00002310750500001510
Coefficient of coupling H1、H2Are respectively as
Figure BSA00002310750500001511
Figure BSA00002310750500001512
The coupling coefficient only represents the coupling inside the system without considering the digital control delay, and the control method can effectively reduce the coupling inside the system by combining with the figure 4. Considering the digital control delay, the coupling coefficient includes the coupling condition of the system interior and the delay link, and in combination with fig. 5, it can be seen that the control method of the invention can effectively reduce the coupling caused by the delay link and also can effectively inhibit the coupling caused by the delay link.
Step 6, converting the obtained current iα、iβComparing with reference current, and obtaining a three-phase modulation signal u through a complex vector decoupling loop and Clark inverse transformationa、ub、uc；
Step 7, three-phase modulation signal ua、ub、ucThe pulse width modulation signal is generated by the sine pulse width modulation unit, and the work of a VIENNA rectifier switching tube is controlled by a driving circuit.
The modulation rule of the VIENNA rectifier is as follows: as shown in FIG. 3, taking phase A as an example, in the positive half cycle of the modulated wave, when the carrier wave is larger than the modulated wave, S is seta1、Sa2Conducting, the voltage of the A-phase bridge arm is 0, and when the carrier wave is less than the modulation wave, making Sa1、Sa2Turn off, the bridge arm voltage of A phase is U dc2; in the negative half cycle of the modulated wave, when the carrier wave is smaller than the modulated wave, let Sa1、Sa2Conducting, the voltage of the A-phase bridge arm is 0, and when the carrier wave is greater than the modulation wave, making Sa1、Sa2Turn off, the bridge arm voltage of A phase is-Udc/2. B. The modulation strategy of the C two phases is the same as that of the A phase.
Wherein U isdcIs the voltage of the direct current bus at the output side of the VIENNA rectifier.
Example 1
In this embodiment, a three-phase VIENNA rectifier circuit is built by using a Simulink tool in MATLAB, and the input voltage is rectified by the three-phase VIENNA rectifier circuit to obtain direct current.
The electrical parameter settings during the simulation are as in table 1:
TABLE 1
Figure BSA0000231075050000161
The simulation mainly completes the comparative simulation of the traditional proportional resonance control method and the improved decoupling-based proportional resonance control method under two switching frequencies of 5kHz and 2.5 kHz. Before analyzing the dynamic performance of the VIENNA rectifier, simulation analysis is performed on the steady-state performance of the VIENNA rectifier under the power grid condition, and as can be seen from fig. 6, when the switching frequency is 5kHz and 2.5kHz, the control method can realize that three-phase current on the alternating current side is sinusoidal and the voltage on the direct current side is constant at a given voltage when the voltage of the power grid is unbalanced, which shows that the decoupling-based current control method designed by the invention can enable the VIENNA rectifier to normally operate when the voltage of the power grid is unbalanced.
Comparing the waveforms of the reactive power in fig. 7 (a) and fig. 7 (b) and fig. 8 (a) and fig. 8 (b), it can be seen that, by adopting the improved decoupling-based proportional resonance control method, when the active power suddenly changes, the transient change range of the reactive power average value is smaller and the time for recovering the stability is shorter than that of the conventional proportional resonance control method. Therefore, as can be seen from a comparison between fig. 7 and fig. 8, the decoupling-based proportional resonance control method provided herein can effectively reduce the coupling between the active power and the reactive power, and improve the dynamic performance of the system. Comparing fig. 7 (a) with fig. 8 (a), it can be found that when the conventional proportional resonance control method is adopted, after the switching frequency is decreased from 5kHz to 2.5kHz, it can be seen that the amplitude of the reactive transient change is increased when the active transient change is suddenly changed, and the time for recovering the stability is prolonged, which indicates that the coupling between the powers is aggravated by the delay link of the system after the switching frequency is decreased. Moreover, as can also be seen from the comparison between the waveforms of the reactive power in fig. 8 (a) and fig. 8 (b), the decoupling-based proportional resonance control method proposed herein can effectively reduce the coupling between the active power and the reactive power, and improve the dynamic performance of the system.
In summary, the device and method for current loop decoupling control based on complex vectors in a static coordinate system are applied to a VIENNA rectifier under the condition of a low-switching-frequency non-ideal power grid, the control method determines a delay decoupling link through determination of delay time of the static coordinate system, coupling between active power and reactive power under the condition of the low-switching-frequency non-ideal power grid is effectively inhibited, positive and negative sequence decomposition of current in the static coordinate system is avoided through simplification of reference current, system calculation is simplified, and unnecessary delay and errors are avoided. The invention also deduces a relational expression of the coupling coefficient between the active power and the reactive power under the non-ideal power grid condition, and can visually display the coupling condition between the active power and the reactive power in the system.

Claims (5)

1. A complex vector current loop decoupling control device under a static coordinate system is characterized by comprising a VIENNA rectifier, a digital processing control module and a driving circuit, wherein the digital processing control module comprises a sampling unit, a voltage control unit, a reference current calculation unit, a complex vector current controller and a sine pulse width modulation unit;
the sampling unit respectively collects voltage signals of an upper capacitor and a lower capacitor on the direct current side of the VIENNA rectifier, three-phase voltage signals on the alternating current side of the VIENNA rectifier and three-phase current signals on the alternating current side of the VIENNA rectifier;
the voltage control unit processes the voltage signals of the upper capacitor and the lower capacitor on the direct current side into active power reference signals;
the three-phase voltage signal and the three-phase current signal coordinate are transformed, and the reference current calculating unit processes the active power reference signal and the voltage and current signals obtained after the coordinate transformation into reference current i under a static coordinate system* α、i* β；
The complex vector current controller processes the current reference signal to obtain a modulated wave signal, and the modulated wave signal is sent to the sine pulse width modulation unit;
the output end of the sine pulse width modulation unit is connected to each switching tube of each phase bridge arm in the three-level VIENNA rectifier through a driving circuit;
according to the active power reference signal, extracting a power grid voltage characteristic value and calculating reference current to obtain reference current i under an alpha beta coordinate system* α、i* βThe method comprises the following steps:
non-ideal grid voltage ea(t)、eb(t)、ec(t) can be decomposed into positive and negative sequence components, and the expression under the abc coordinate system is:
Figure FSB0000198224240000011
wherein subscripts a, b, c represent phases a, b, c; superscript +, -represents positive sequence component and negative sequence component, respectively;
Figure FSB0000198224240000012
representing the magnitude of the positive sequence component,
Figure FSB0000198224240000013
representing the magnitude of the negative sequence component; omega is the fundamental angular frequency of the grid voltage;
the network side voltage e under the alpha beta coordinate system can be obtained through Clark transformationα(t)、eβ(t) is:
Figure FSB0000198224240000014
wherein,
Figure FSB0000198224240000015
represents the magnitude of the positive sequence component in the alpha beta coordinate system,
Figure FSB0000198224240000016
representing the amplitude of the negative sequence component in an alpha beta coordinate system;
according to the nature of the Clark transformation,
Figure FSB0000198224240000017
rotates counterclockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system,
Figure FSB0000198224240000018
clockwise at an angular velocity ω relative to the α axis in the α β coordinate system;
Figure FSB0000198224240000019
is stationary relative to the fundamental positive-sequence rotational coordinate system,
Figure FSB00001982242400000110
relative rest with the fundamental frequency negative sequence rotating coordinate system;
the fundamental frequency positive sequence rotation coordinate system rotates anticlockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system; the fundamental frequency negative sequence rotating coordinate system rotates clockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system;
defining: characteristic value of network voltage
Figure FSB00001982242400000111
Are respectively as
Figure FSB00001982242400000112
Projections on a d axis and a q axis in a fundamental frequency positive sequence rotating coordinate system; characteristic value of network voltage
Figure FSB0000198224240000021
Are respectively as
Figure FSB0000198224240000022
Projections on a d axis and a q axis in a fundamental frequency negative sequence rotating coordinate system;
the characteristic value of the current can be obtained by the same method
Figure FSB0000198224240000023
According to the instantaneous reactive power theory, the complex power s (t) can be expressed as:
Figure FSB0000198224240000024
wherein j is a complex number unit, p (t) is instantaneous active power, q (t) is instantaneous reactive power, eα、eβRespectively three-phase network voltage ea、eb、ecAlpha-axis component, beta-axis component, i after Clark transformationα、iβAre respectively three-phase currents ia、ib、icAlpha-axis component and beta-axis component after Clark transformation;
three-phase voltage and current are represented as direct current quantities under a two-phase dq rotating coordinate system, the derivation process of reference current can be effectively simplified, and the network-access instantaneous active power p (t) and the network-access instantaneous reactive power q (t) can be obtained according to the formula:
Figure FSB0000198224240000025
in the formula, pc2(t)、ps2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous active power; p is a radical of0(t) is the dc component in the net-entry instantaneous active power; q. q.sc2(t)、qs2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous reactive power; q. q of0(t) is the dc component in the network-entry instantaneous reactive power;
the specific expressions are respectively as follows:
Figure FSB0000198224240000026
when the coordinate system is changed back to the α β coordinate system, the expression is:
Figure FSB0000198224240000027
wherein
Figure FSB0000198224240000028
After integration, it can be expressed in matrix form as:
Figure FSB0000198224240000031
inverse solution matrix equation, by obtaining reference current under different control targets
Figure FSB0000198224240000032
And introducing a coefficient k into the reference current expression, the reference current expression can be simplified as follows:
Figure FSB0000198224240000033
wherein
Figure FSB0000198224240000034
Different controls are realized mainly by changing the k value in the control process: when k is-1, constant active power control is mainly used for eliminating secondary fluctuation of active power; when k is 0, inhibiting the negative sequence current to balance the output three-phase current; when k is 1, the constant reactive power control mainly eliminates the secondary fluctuation of the reactive power.
2. The complex vector current loop decoupling control device under the static coordinate system as claimed in claim 1, wherein the digital processing control module is TMS320F28377D and EPM1270T chips.
3. A complex vector current loop decoupling control method under a static coordinate system is characterized by comprising the following steps:
step 1, in each switching period, a sampling unit of a digital control module respectively collects three-phase voltage e of the alternating current side of a VIENNA rectifiera、eb、ecAlternating side three-phase current ia、ib、icCapacitor voltage U on the DC sideC1And a dc side lower capacitor voltage;
step 2, according to the signals collected in the step 1, the voltage and the current on the alternating current side in the static abc coordinate system are converted into a static alpha beta coordinate system through Clark, and the voltage U of the capacitor on the direct current side is converted into a static alpha beta coordinate systemC1、UC2Comparing the active power reference signal with a voltage reference signal, obtaining an error signal through proportional-integral regulation, and multiplying the error signal by the voltage reference signal to obtain an active power reference signal;
step 3, extracting a grid voltage characteristic value according to the obtained active power reference signal, and calculating a reference current to obtain a reference current i under an alpha beta coordinate system* α、i* β；
Step 4, according to the switching frequency f of the three-level VIENNA rectifiersDetermining the delay time tau of a systemdComprises the following steps:
Figure FSB0000198224240000035
step 5, determining a complex vector current controller according to the calculated delay time, and verifying the effectiveness of the complex vector current controller through the coupling coefficient analysis of the system;
step 6, converting the three-phase current ia, ib and ic on the alternating current side to obtain a current iα、iβComparing with reference current, and obtaining three-phase modulation signal u through complex vector current controller and Clark inverse transformationa、ub、uc；
Step 7, the three-phase modulation signal generates a pulse width modulation signal through a sine pulse width modulation unit, and the work of a VIENNA rectifier switching tube is controlled through a driving circuit;
extracting a grid voltage characteristic value and calculating reference current to obtain reference current i under an alpha beta coordinate system* α、i* βThe method comprises the following steps:
(3.1) non-ideal grid Voltage ea(t)、eb(t)、ec(t) can be decomposed into positive and negative sequence components, and the expression under the abc coordinate system is:
Figure FSB0000198224240000041
wherein subscripts a, b, c represent a phase a, b phase, c phase; superscript +, -respectively represents positive sequence component and negative sequence component;
Figure FSB0000198224240000042
representing the magnitude of the positive sequence component,
Figure FSB0000198224240000043
representing the magnitude of the negative sequence component; omega is the fundamental angular frequency of the grid voltage;
(3.2) obtaining the network side voltage e under the alpha beta coordinate system through Clark transformationα(t)、eβ(t) is:
Figure FSB0000198224240000044
wherein,
Figure FSB0000198224240000045
represents the magnitude of the positive sequence component in the alpha beta coordinate system,
Figure FSB0000198224240000046
representing the amplitude of the negative sequence component in an alpha beta coordinate system;
(3.3) according to the characteristics of Clark transform,
Figure FSB0000198224240000047
rotates counterclockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system,
Figure FSB0000198224240000048
clockwise at an angular velocity ω relative to the α axis in the α β coordinate system;
Figure FSB0000198224240000049
is stationary relative to the fundamental positive-sequence rotational coordinate system,
Figure FSB00001982242400000410
relative rest with the fundamental frequency negative sequence rotating coordinate system;
(3.4) rotating the coordinate system counterclockwise with an angular velocity ω with respect to the α -axis in the α β coordinate system in the fundamental positive sequence; the fundamental frequency negative sequence rotating coordinate system rotates clockwise with an angular velocity omega relative to the alpha axis in the alpha beta coordinate system;
(3.5) definition: characteristic value of network voltage
Figure FSB00001982242400000411
Are respectively as
Figure FSB00001982242400000412
Projections on a d axis and a q axis in a fundamental frequency positive sequence rotating coordinate system; characteristic value of network voltage
Figure FSB00001982242400000413
Are respectively as
Figure FSB00001982242400000414
Projections on a d axis and a q axis in a fundamental frequency negative sequence rotating coordinate system;
similarly to the steps (3.1) to (3.5), the current characteristic value can be obtained
Figure FSB00001982242400000415
(3.6) according to the instantaneous reactive power theory, the complex power s (t) can be expressed as:
Figure FSB00001982242400000416
wherein j is a complex number unit, p (t) is instantaneous active power, q (t) is instantaneous reactive power, eα、eβRespectively three-phase mains voltage ea、eb、ecAlpha-axis component, beta-axis component, i after Clark transformationa、iβAre respectively three-phase currents ia、ib、icAlpha-axis component and beta-axis component after Clark transformation;
three-phase voltage and current are represented as direct current quantities under a two-phase dq rotating coordinate system, the derivation process of reference current can be effectively simplified, and the network-access instantaneous active power p (t) and the network-access instantaneous reactive power q (t) can be obtained according to the formula:
Figure FSB0000198224240000051
in the formula, pc2(t)、ps2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous active power; p is a radical of0(t) is the dc component in the net-entry instantaneous active power; q. q.sc2(t)、qs2(t) is a coefficient corresponding to a second harmonic contained in the instantaneous reactive power; q. q.s0(t) is the dc component in the network-entry instantaneous reactive power;
the specific expressions are respectively as follows:
Figure FSB0000198224240000052
when the coordinate system is changed back to the α β coordinate system, the expression is:
Figure FSB0000198224240000053
wherein
Figure FSB0000198224240000054
After integration, it can be represented in matrix form as:
Figure FSB0000198224240000055
(3.7) inverse solving the matrix equation, and obtaining the reference current under different control targets
Figure FSB0000198224240000061
And introducing a coefficient k into the reference current expression, the reference current expression can be simplified as follows:
Figure FSB0000198224240000062
wherein
Figure FSB0000198224240000063
Different controls are realized mainly by changing the k value in the control process: when k is-1, constant active power control is mainly used for eliminating secondary fluctuation of active power; when k is 0, the negative sequence current is restrained, and the output three-phase current is balanced; when k is 1, the constant reactive power control mainly eliminates the secondary fluctuation of the reactive power.
4. The complex vector current loop decoupling control method according to claim 3, wherein the complex vector current controller is determined according to the calculated delay time in step 5, and specifically comprises the following steps:
(4.1) the delay time tau brought by signal sampling and PWM inertia link isdSelecting as follows:
Figure FSB0000198224240000064
wherein f issThe switching frequency is the corresponding delay time will be increased along with the reduction of the switching frequency;
(4.2) Positive sequence vector under alpha and beta coordinate system in time domain
Figure FSB0000198224240000065
And positive sequence vector under dq coordinate system
Figure FSB0000198224240000066
The following relationships exist:
Figure FSB0000198224240000067
according to the determined delay time taudThe positive sequence delay link under the dq coordinate system can be obtained as
Figure FSB0000198224240000068
The time delay link is converted into an alpha beta coordinate system to obtain
Figure FSB0000198224240000069
(4.3) delay time τ according to equation (4.1)dThe positive sequence time delay link under the dq coordinate system can be obtained
Figure FSB00001982242400000610
Comprises the following steps:
Figure FSB00001982242400000611
then the negative sequence time delay link under the corresponding dq coordinate system
Figure FSB00001982242400000612
Comprises the following steps:
Figure FSB00001982242400000613
wherein omega is the fundamental angular frequency of the grid voltage;
(4.4) converting the delay link into an alpha beta coordinate system to obtain Gαβ_d(s) is;
Figure FSB00001982242400000614
(4.5) controlled object G 'added with delay link'VIENNA_αβ(s) is expressed as:
Figure FSB00001982242400000615
l is a filter inductor at the AC side, and R is an equivalent resistance at the AC side;
the delay link also influences the coupling between the active power and the reactive power of the system when the voltage of the power grid is unbalanced, and the coupling degree between the active power and the reactive power is more serious along with the reduction of the switching frequency;
(4.6) according to the delay element of the VIENNA rectifier given in (4.4), a positive sequence delay compensation element can be assumed
Figure FSB0000198224240000071
The expression of (a) is:
Figure FSB0000198224240000072
wherein
Figure FSB0000198224240000073
To delay compensate the angle, there are now:
Figure FSB0000198224240000074
knowing the positive sequence time s ═ j ω, the delay compensation angle at this time can be calculated
Figure FSB0000198224240000075
The positive sequence delay compensation procedure is
Figure FSB0000198224240000076
Negative sequence delay compensation link obtained by the same way
Figure FSB0000198224240000077
For convenience of calculation, the delay compensation link is usually subjected to euler transform:
Figure FSB0000198224240000078
(4.7) consider that the VIENNA rectifier is modeled in the α β coordinate system at low switching frequencies, albeit with current iaAnd iβThere is no coupling between the two, but there is still coupling inside the system, and this coupling can not be eliminated by the traditional proportional resonant controller, so a reduced-order resonant controller is designed to realize the decoupling inside the system;
according to the step (4.2), the positive sequence complex vector current controller under the alpha beta coordinate system can be deduced
Figure FSB0000198224240000079
Is composed of
Figure FSB00001982242400000710
Negative sequence complex vector current controller
Figure FSB00001982242400000711
Comprises the following steps:
Figure FSB00001982242400000712
wherein k ispIs a proportionality coefficient, krIs the resonance coefficient;
in order to realize the simultaneous control of positive and negative sequence components under an alpha-beta coordinate system in a non-ideal power grid and avoid current i under the alpha-beta coordinate systemaAnd iβThe positive and negative sequence separation link can obtain the complex vector current controller G added with the delay compensationαβ(s) is
Figure FSB00001982242400000713
5. The complex vector current loop decoupling control method under the static coordinate system as claimed in claim 3, wherein step 5 derives a coupling coefficient relationship under a non-ideal grid condition, which can visually represent the coupling analysis between active power and reactive power to verify the effectiveness of the complex vector current controller, and the specific results are as follows:
(5.1) the current loop closed loop transfer function G(s) without considering the power grid voltage disturbance is as follows:
Figure FSB0000198224240000081
wherein,
Figure FSB0000198224240000082
is a reference current in an alpha beta coordinate system, iαβ(s) is a sampling current in an alpha beta coordinate system, GVIENNA_αβ(s) is a VIENNA rectifier object transfer function in an alpha beta coordinate system; gαβ(s) is the current controller transfer function; re(s) is the real component of the current loop closed loop transfer function; im(s) is the imaginary component of the current loop closed loop transfer function;
the current feedback value i under the alpha beta coordinate system can be obtained according to the formulaα(s)、iβThe relationship between(s) is:
Figure FSB0000198224240000083
Figure FSB0000198224240000084
(5.2) if the active power command and the reactive power command change according to the step response, and u (t) is the step response change, the active power command p0(t) pu (t), reference reactive power q0(t) Qu (t), and according to a reference current calculation formula, obtaining the reference current of the alpha and beta axes in the time domain
Figure FSB0000198224240000085
Is composed of
Figure FSB0000198224240000086
Figure FSB0000198224240000087
Alpha-beta axis reference current under frequency domain can be obtained by Laplace transformation
Figure FSB0000198224240000088
Is composed of
Figure FSB0000198224240000089
Figure FSB00001982242400000810
(5.3) substituting the current feedback value i in the alpha beta coordinate systemα(s)、iβ(s) availability
Figure FSB00001982242400000811
Figure FSB0000198224240000091
Wherein
Figure FSB0000198224240000092
Figure FSB0000198224240000093
Figure FSB0000198224240000094
Figure FSB0000198224240000095
Transforming the reverse Laplace to time domain to obtain A (t), B (t), C (t), D (t), and current feedback value i of alpha-beta coordinate system in time domainα(t)、iβ(t)：
Figure FSB0000198224240000096
Figure FSB0000198224240000097
(5.4) obtaining expressions of instantaneous active power p (t) and reactive power q (t) according to a calculation formula of instantaneous complex power, wherein the expressions are respectively
Figure FSB0000198224240000098
Figure FSB0000198224240000099
Substituting the current feedback value and the positive and negative sequence voltages under the corresponding alpha and beta coordinate systems to obtain
Figure FSB00001982242400000910
Figure FSB00001982242400000911
(5.5) coupling coefficient H1、H2Are respectively as
Figure FSB0000198224240000101
Figure FSB0000198224240000102
Introducing an unbalance concept, defining the unbalance lambda as the ratio of the negative sequence component amplitude to the positive sequence component amplitude, and obtaining a simplified coupling coefficient expression as follows:
Figure FSB0000198224240000103
Figure FSB0000198224240000104
。
CN202110065647.2A 2021-01-18 2021-01-18 Complex vector current loop decoupling control device and method under static coordinate system Active CN112653342B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110065647.2A CN112653342B (en) 2021-01-18 2021-01-18 Complex vector current loop decoupling control device and method under static coordinate system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110065647.2A CN112653342B (en) 2021-01-18 2021-01-18 Complex vector current loop decoupling control device and method under static coordinate system

Publications (2)

Publication Number Publication Date
CN112653342A CN112653342A (en) 2021-04-13
CN112653342B true CN112653342B (en) 2022-07-19

Family

ID=75368539

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110065647.2A Active CN112653342B (en) 2021-01-18 2021-01-18 Complex vector current loop decoupling control device and method under static coordinate system

Country Status (1)

Country Link
CN (1) CN112653342B (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113517704B (en) * 2021-04-27 2022-12-13 合肥工业大学 Voltage fluctuation suppression method based on flexible multi-state switch direct current side
CN113437895B (en) * 2021-06-30 2023-10-13 浙江大学 Matrix vector angle proportional resonance control method
CN114142751B (en) * 2021-12-06 2023-12-26 重庆理工大学 Three-phase CSR proportional integral resonance control method under unbalanced power grid voltage
CN114094847B (en) * 2021-12-06 2024-06-04 南京理工大学 Method for optimizing input current of VIENNA rectifier under wide-range unbalanced power grid

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103997263A (en) * 2014-05-28 2014-08-20 东南大学 Transformer substation patrol robot position detecting method based on high-frequency injection method
CN106787650A (en) * 2016-12-23 2017-05-31 合肥工业大学 The Direct Current instruction computational methods that active secondary pulsation suppresses under unbalanced power supply

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7359224B2 (en) * 2005-04-28 2008-04-15 International Rectifier Corporation Digital implementation of power factor correction
US20130181654A1 (en) * 2012-01-18 2013-07-18 Hamilton Sundstrand Corporation Motor drive system employing an active rectifier

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103997263A (en) * 2014-05-28 2014-08-20 东南大学 Transformer substation patrol robot position detecting method based on high-frequency injection method
CN106787650A (en) * 2016-12-23 2017-05-31 合肥工业大学 The Direct Current instruction computational methods that active secondary pulsation suppresses under unbalanced power supply

Also Published As

Publication number Publication date
CN112653342A (en) 2021-04-13

Similar Documents

Publication Publication Date Title
CN112653342B (en) Complex vector current loop decoupling control device and method under static coordinate system
CN110021953B (en) Direct-current side voltage control method of flexible multi-state switch during power grid voltage unbalance
CN110165924B (en) Improved dead-beat control method of single-phase PWM rectifier
WO2014079124A1 (en) Model prediction control method for voltage source-type rectifier when grid voltage is unbalanced
CN107908829B (en) Onboard electric systems method for analyzing stability based on unified large-signal model
Xiao et al. Virtual flux direct power control for PWM rectifiers based on an adaptive sliding mode observer
CN113839388B (en) Current double-loop control method of active power filter based on hybrid load
CN113629763B (en) Current control method and system for medium-voltage direct-hanging energy storage converter under non-ideal power grid
CN114583702B (en) Parallel current control system and control method of LCL type active power filter
CN110224431B (en) Control method for reducing influence of phase-locked loop in grid-connected inverter system
CN113098033B (en) Self-adaptive virtual inertia control system and method based on flexible direct current power transmission system
CN103117562A (en) Control method of high-voltage cascade energy feedback converter power module
CN109193793B (en) Converter voltage detection-free grid-connected control system and method
CN110365230A (en) A kind of Three-phase PWM Voltage Rectifier direct Power Control device
CN111262460B (en) Five-level rectifier sliding mode PIR control method based on coupling inductor
CN106533238A (en) Voltage compensation-based grid-connected inverter control method for marine electrical system
CN111525551B (en) Target control method and system for rectifier under unbalanced power grid voltage
CN111756261B (en) PWM rectifier control method and device
CN112350595B (en) Analog impedance control method for inhibiting input unbalance influence of AC/DC matrix converter
Fu et al. Improved control method of grid-connected converter based on voltage perturbation compensation under weak grid conditions
CN210608909U (en) Inverter current control system based on self-adaptive current harmonic suppression
CN114094847A (en) Method for optimizing VIENNA rectifier input current under wide-range unbalanced power grid
CN114465270A (en) One-stop intelligent megawatt box system based on TE-SVM modulation, intelligent controller and control method thereof
CN109066712B (en) Phase splitting control method and system for three-phase four-wire parallel type three-level SVG
CN111969643A (en) Differential flat control method for MMC-HVDC (modular multilevel converter-high voltage direct current) supplying power to passive network under asymmetric fault

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
DD01 Delivery of document by public notice

Addressee: Lv Jianguo

Document name: Notice of registration

DD01 Delivery of document by public notice
GR01 Patent grant
GR01 Patent grant