CN108880309B - A kind of three direct tracking and controlling method of level grid-connected converter transient current of I type - Google Patents
A kind of three direct tracking and controlling method of level grid-connected converter transient current of I type Download PDFInfo
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- CN108880309B CN108880309B CN201810870740.9A CN201810870740A CN108880309B CN 108880309 B CN108880309 B CN 108880309B CN 201810870740 A CN201810870740 A CN 201810870740A CN 108880309 B CN108880309 B CN 108880309B
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- 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
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
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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
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Abstract
The invention discloses a kind of three direct tracking and controlling method of level grid-connected converter transient current of I type, voltage, each phase voltage instantaneous value of power grid and current transformer reality output transient current at each regulation period real-time sampling current transformer DC bus capacitor device end；The different working condition of three level grid-connected converters is analyzed, calculates and exports current change quantity and transient current shift factor under each effective working condition；According to each phase network voltage polarity, by the significant instant current displacement factor in the mutually selection regulation period, utilize each phase current desired value, actual value and the selected significant instant current displacement factor, the action time of each significant instant current displacement factor and the PWM control pulse width of each switching tube are calculated, realizes that exporting transient current to current transformer directly controls by pulsewidth modulation.
Description
Technical field
The present invention relates to grid type electronic power convertor equipments to export current follow-up control technical field, and in particular to a kind of
The grid-connected converter device of three level main circuit topological structure of I type exports the direct tracking and controlling method of transient current.
Background technique
Such as active power filter (APF), static reactive generator (SVG), photovoltaic/wind-power electricity generation, energy storage are with two-way
The various grid type electronic power conversion devices such as current transformer, PWM rectifier, output end is concatenated reactor and power grid connects
It connects, this kind of device mainly exports electric current by accurately and fast controlling it under line voltage support to realize its specific function
It can require.Therefore, such device mainly includes output current-order generation technique and output current follow-up control in terms of observing and controlling
Technology.
All kinds of grid type converter plant main circuits mostly use two level and three level in 380V/220V low pressure utility grid
Topological structure, three level-types are good with waveform quality compared with two level-types, low feature performance benefit is lost.Tradition output current tracking control
Method processed mainly includes Hysteresis Current compares, space vector of voltage controls etc..Chinese patent 201110281870.7 is for two electricity
The Active Power Filter-APF of flat main circuit topological structure proposes transient current and directly controls implementation method, has data calculation amount
Less, the features such as pulsewidth utilization rate is high, tracing control effect is good, but this method is not suitable for three level grid-connected converters.Therefore, such as
What designs a kind of three level grid-connected converters output direct tracking and controlling method of transient current, is still technical problem to be solved.
Summary of the invention
In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a kind of three level grid-connected converter of I type is instantaneously electric
Direct tracking and controlling method is flowed, the grid-connected converter of I type three-level topology structure is directed to, is become by analysis three level of I type
The effective working condition of device is flowed, card is pushed away and obtains three significant instant current displacement factors, and furthermore present each switch element
PWM pulsewidth calculation formula, so as to by pulsewidth modulation realize to current transformer export the direct tracing control of transient current, have
The feature performance benefits such as clear concept, calculation amount are small, pulsewidth utilization rate is high, regulation is accurate.
The technical scheme adopted by the invention is that:
The first object of the present invention is to provide a kind of three direct tracing control side of level grid-connected converter transient current of I type
Method, method includes the following steps:
Voltage, each phase voltage instantaneous value of power grid and change at each regulation period real-time sampling current transformer DC bus capacitor device end
Flow device actual output current instantaneous value；
For the different working condition of three level grid-connected converter of I type, each effective working condition is analyzed to output electric current
Incentive action calculates and generates each transient current shift factor；
It is utilized according to each real-time polarity of phase network voltage by the significant instant current displacement factor in the mutually selection regulation period
Each phase current desired value, actual value and the selected significant instant current displacement factor, calculate each significant instant current displacement
The PWM of the action time of the factor and each switching tube controls pulse width, is realized by pulsewidth modulation and exports instantaneous electricity to current transformer
Stream directly controls.
Further, regulate and control cycle T in a PWMSInterior, the switch transistor T 1 and switch transistor T 3 of three level grid-connected converters are mutual
Conducting, the conducting complementary with switch transistor T 4 of switch transistor T 2 are mended, switch transistor T 1 to T4 is sequentially connected, the working condition of the current transformer are as follows:
S1=(switch transistor T 1 is open-minded, and switch transistor T 2 is open-minded, and switch transistor T 3 turns off, and switch transistor T 4 turns off)；
S2=(switch transistor T 1 turns off, and switch transistor T 2 is open-minded, and switch transistor T 3 turns off, and switch transistor T 4 turns off)；
S3=(switch transistor T 1 turns off, and switch transistor T 2 is open-minded, and switch transistor T 3 is open-minded, and switch transistor T 4 turns off)；
S4=(switch transistor T 1 turns off, and switch transistor T 2 turns off, and switch transistor T 3 is open-minded, and switch transistor T 4 turns off),
S5=(switch transistor T 1 turns off, and switch transistor T 2 turns off, and switch transistor T 3 is open-minded, and switch transistor T 4 is open-minded)；
Wherein, S1, S3, S5 are effective working condition, and S2, S4 are the transition shape of experience of effective working condition transition period
State.
Further, the calculation method of current change quantity is exported under each effective working condition are as follows:
In t moment, sampling end capacitor E1 end voltage on DC side is udc1(t), network voltage uS(t), electric current is exported
For ic(t), output current-limiting reactor inductance is LC；
When current transformer works in S1 state, T1, T2 pipe are simultaneously turned on, the shutdown of T3, T4 pipe, T1, T2 pipe constant conduction time
For t12on, when showing that current transformer works in S1 state, export current change quantity Δ iC_rpAre as follows:
ΔiC_rp(t+t12on)={ [udc1(t)-uS(t)]/LC}*t12on
When current transformer works in S3 state, T2, T3 pipe are simultaneously turned on, the shutdown of T1, T4 pipe, and T2, T3 pipe turn-on time are
t23on, when showing that current transformer works in S3 state, export current change quantity Δ iC_rnAre as follows:
ΔiC_rn(t+t23on)=- { uS(t)/LC}*t23on
When current transformer works in S5 state, T3, T4 pipe are simultaneously turned on, and the shutdown of T1, T2 pipe, T3, T4 manage common turn-on time
For t34on, when showing that current transformer works in S5 state, export current change quantity Δ iC_dpAre as follows:
ΔiC_dp(t+t34on)=- { [udc2(t)+uS(t)]/LC}*t34on。
Further, under each effective working condition transient current shift factor expression formula are as follows:
Transient current shift factor δ i when current transformer works in S1 stateC_rpAre as follows:
δiC_rp=(udc1-uS)/LC
Transient current shift factor δ i when current transformer works in S3 stateC_rnAre as follows:
δiC_rn=-uS/LC
Transient current shift factor δ i when current transformer works in S5 stateC_dpAre as follows:
δiC_dp=-(udc2+uS)/LC
In formula, udc1、udc2The respectively upper and lower capacitor end voltage of DC side, uSFor grid side phase voltage, LCFor output string
Join reactor inductance amount.
Further, the action time of the transient current shift factor be equal to one modulation period TSInterior curent change
Measure Δ iCWith current displacement factor delta iCRatio.
Further, the calculation method of the action time of the transient current shift factor are as follows:
Sampling k moment current transformer reality output transient current is i (k), if k+1 moment expectation electric current value is i (k+1)；
When export electric current i (k) it is non-negative, output voltage u (k) is non-negative when, one modulation period TSInterior selection significant instant
The current displacement factor is δ iC_rnWith δ iC_rp, δ iC_rpAction time t12onFor switch transistor T 1, T2 service time, δ iC_rnEffect
Time t23onI.e. switch transistor T 2, T3 turn-on time, can obtain:
t2on=Ts
t2onPulse width is controlled for the PWM of switch transistor T 2；
When output electric current i (k) be negative, output voltage u (k) be it is non-negative when, one modulation period TSInterior selection effective wink
When the current displacement factor be δ iC_rnWith δ iC_rp, δ iC_rpAction time t12onFor switch transistor T 1, T2 service time, δ iC_rnWork
With time t23onFor switch transistor T 2, the turn-on time of T3, can obtain:
t2on=Ts
When output electric current i (k) be it is non-negative, when output voltage u (k) is negative, one modulation period TSInterior selection effective wink
When shift factor be δ iC_rnWith δ iC_dp, δ iC_rnAction time t23onFor switch transistor T 2, T3 service time, δ iC_dpEffect when
Between t34onFor switch transistor T 3, the turn-on time of T4, in modulation period TSInterior switch transistor T 3 is constantly on, and switch T1 pipe closes always
It closes, can obtain:
t1on=0；
When output electric current i (k) be negative, when output voltage u (k) is negative, one modulation period TSInterior selection significant instant
Shift factor is δ iC_dpWith δ iC_rn, δ iC_rnAction time t23onFor switch transistor T 2, T3 service time, δ iC_dpAction time
t34onFor switch transistor T 3, the turn-on time of T4, in modulation period TSInterior switch transistor T 3 is constantly on, and switch T1 pipe is closed always,
It can obtain:
t1on=0；
Further, the calculation method of the PWM control pulse width of each switching tube are as follows:
When network voltage Us > 0, the PWM control pulse width t of switch transistor T 1, T2, T3 and T41on、t2on、t3on、t4onRespectively
Are as follows:
t2on=Ts
t4on=0
As network voltage Us< 0, the PWM control pulse width t of switch transistor T 1, T2, T3 and T41on、t2on、t3on、t4onRespectively
Are as follows:
t1on=0
t3on=Ts
In formula:
Wherein, udc1、udc2For the end current transformer DC bus capacitor device E1, E2 voltage；uSFor network voltage；LCFor series reactance
Device inductance；I (k) is k moment current transformer reality output transient current, and i (k+1) is k+1 moment expectation electric current value；TsFor regulation
Period.
Further, described realized by pulsewidth modulation exports the method that transient current directly controls to current transformer are as follows:
Start DSP and carry on piece PWM peripheral functionality, according to scheduled current regulation cycle TSPWM is set and regulates and controls period ginseng
Number controls pulse width according to the PWM of each switching tube and each PWM time register is arranged, and is opened by the realization of PWM peripheral hardware current transformer
Off status control makes to export the variation of current tracking instruction current.
The second object of the present invention is to provide a kind of computer installation, and the device is for realizing three level grid-connected converter of I type
Device transient current direct tracing control can be run on a memory and on a processor including memory, processor and storage
Computer program, the processor realize following steps when executing described program, comprising:
It is instantaneously electric to sample current transformer DC bus capacitor device end voltage, each phase power grid instantaneous voltage and current transformer reality output
Stream；
The different working condition of three level grid-connected converters is analyzed, calculates and exports electric current under each effective working condition
Variable quantity and transient current shift factor；
Each phase is utilized by the significant instant current displacement factor in the mutually selection regulation period according to each phase network voltage polarity
Current expected value, actual value and the selected significant instant current displacement factor, calculate each significant instant current displacement factor
Action time and each switching tube PWM control pulse width, by pulsewidth modulation realize to current transformer export transient current it is straight
Connect control.
Compared with prior art, the beneficial effects of the present invention are:
(1) present invention is directed to I type three level grid-connected converter topological features, its normal operating conditions of analysis and summary
And effective output state, obtained three effective transient current shift factor expression formulas, and analyze transient current displacement because
Son to the incentive action of output state, from which further followed that accordingly three level grid-connected converter transient current of realization I type directly with
The PWM pulsewidth calculation formula of track control respectively switched, is realized by pulsewidth modulation to three level grid-connected converter transient current of I type
Direct tracing control has reached preferable output current wave quality, and demonstrates correct, validity of the invention；
(3) compared with traditional three-level current transformer control method, the present invention is directed I type three-level topology structure
Grid-connected converter has obtained three effective transient current shift factors according to the effective working condition of current transformer, and calculates and respectively open
The PWM pulsewidth of pass realizes by pulsewidth modulation and exports the direct tracing control of transient current to current transformer have clear concept, meter
The feature performance benefits such as calculation amount is small, pulsewidth utilization rate is high, regulation is accurate.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is the single-phase bridge arm circuit diagram of I type three-level current transformer；
Fig. 2 is output current of converter tracing control process schematic；
Fig. 3 is three level grid-connected converter of I type emulation main circuit schematic diagram；
Fig. 4 is I type three-level current transformer output current wave figure；
Fig. 5 is I type three-level current transformer output current distortion rate figure；
Fig. 6 is exchange side phase voltage/current waveform schematic diagram under PWM rectification mode；
Fig. 7 is exchange side phase voltage/current waveform schematic diagram under the mode of generating electricity by way of merging two or more grid systems；
Fig. 8 is I type three-level current transformer output line voltage waveform diagram.
Specific embodiment
The invention will be further described with embodiment with reference to the accompanying drawing.
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field
The identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
As background technique is introduced, to overcome the deficiencies of traditional three-level control principle concept is cumbersome, method is complicated, in order to
Technical problem as above is solved, present applicant proposes a kind of three direct tracing control sides of level grid-connected converter transient current of I type
Method.
1, function analysis of the three each switch state of level grid-connected converter of I type to output electric current
In view of current regulation cycle TsVery little (generally 100 μ s or following), it is believed that direct current in a regulation period
The end voltage v of side capacitors E1, E2cd1、vcd2And each phase voltage instantaneous value u of grid sidesIt remains unchanged, if current-limiting reactor LC?
It is not saturated in work.Influence using single-phase simplified circuit detailed analysis different converter working condition to output electric current.
As shown in Figure 1, in three level bidirectional converters, for Mr. Yu's single-phase bridge arm, switch transistor T 1 and switch transistor T 3
The phenomenon that complementation, switch transistor T 2 is complementary with switch transistor T 4, and there can be no switch transistor T 1 is open-minded, and switch transistor T 2 turns off.So each
The conducting situation of switch element is divided into following five kinds in normal operating conditions, and wherein S1, S3, S5 are effective working condition, S2, S4
It is transition state caused by complementary transitions are delayed through dead zone, such as table 1 for the transition transient state of experience of effective working condition transition period
It is shown.
15 kinds of working conditions of table
| State | T1 | T2 | T3 | T4 |
| S1 | 1 | 1 | 0 | 0 |
| S2 | 0 | 1 | 0 | 0 |
| S3 | 0 | 1 | 1 | 0 |
| S4 | 0 | 0 | 1 | 0 |
| S5 | 0 | 0 | 1 | 1 |
Direction that output current of converter flows to power grid is set as positive direction, the state table of electric current can will be exported according to polarity
It is shown as { (ia>=0), (ia< 0) }；Similarly, the state of network voltage can also be divided into { (U by polaritya>=0), (Ua< 0) }.Root
Current transformer is divided into 4 effective output states according to output current polarity, output voltage polarity, as shown in table 2:
Table 2 current transformer, 4 effective output states
| Output state | Current/voltage polarity |
| O1 | Ia≥0,ua≥0 |
| O2 | Ia≥0,ua<0 |
| O3 | Ia<0,ua≥0 |
| O4 | Ia<0,ua<0 |
Three kinds of three level grid-connected converter of comprehensive analysis I type effective switch states swashing under four kinds of output states below
The effect of encouraging.
(1) current transformer works in S1 state
Such as Fig. 1, it is assumed that work in S1 state in t moment current transformer, T1, T2 pipe simultaneously turn on, the shutdown of T3, T4 pipe.Sampling
End capacitor E1 voltage is u on DC sidedc1(t), network voltage uS(t), output electric current is ic(t), current-limiting reactor is exported
Inductance is LC, T1, T2 pipe constant conduction time are t12on, it can be deduced that:
iC(t+t12on)={ [udc1(t)-uS(t)]/LC}*t12on+iC(t)
That is: iC(t+t12on)-iC(t)={ [udc1(t)-uS(t)]/LC}*t12on
It is denoted as: Δ iC_rp(t)={ [udc1(t)-uS(t)]/LC}*t12on (1)
In formula, Δ iC_rpCurrent change quantity is exported when working in S1 state for current transformer；t12onIt is common for switch transistor T 1, T2
The time of conducting.
Formula (1), which clearly characterizes S1 state lower switch pipe T1, T2 while opening, directly controls effect to output electric current.At this
Under state, the electric energy of E1 storage is discharged by T1, T2 and through output reactance device to source side, and output electric current forward direction increases, output
Current change quantity is determined by the end E1 voltage, power grid instantaneous voltage, output current-limiting reactor and S1 state duration.
(2) current transformer works in S3 state
Assuming that working in S3 state in t moment current transformer, T2, T3 pipe are simultaneously turned on, the shutdown of T1, T4 pipe.Sample power grid electricity
Pressure is uS(t), output electric current is ic(t), output current-limiting reactor inductance is LC, T2, T3 pipe turn-on time are t23on, can be with
It obtains:
ΔiC_rn(t)=- { uS(t)/LC}*t23on (2)
In formula, Δ iC_rnCurrent change quantity is exported when working in S3 state for current transformer；t23onIt is common for switch transistor T 2, T3
The conducting effective time of the time of conducting, switch transistor T 2 and T3.
Formula (2), which clearly characterizes S2 state lower switch pipe T2, T3 while opening, directly controls effect to output electric current.At this
Under state, output current change quantity is determined by power grid instantaneous voltage, output current-limiting reactor and S3 state duration.
(3) current transformer works in S5 state
Assuming that working in S5 state in t moment current transformer, T3, T4 pipe are simultaneously turned on, the shutdown of T1, T2 pipe.Sample current transformer
End capacitor E2 end voltage is u under DC sidedc2(t), network voltage uS(t), output electric current is ic(t), series reactance is exported
Device is LC, it is t that T3, T4, which manage common turn-on time,34on, it can be deduced that:
ΔiC_dp(t+t34on)=- { [udc2(t)+uS(t)]/LC}*t34on (3)
In formula, Δ iC_dpCurrent change quantity is exported when working in S5 state for current transformer；t34onCommon conducting is managed for T3, T4
Time.
Formula (3), which clearly characterizes S5 state lower switch pipe T3, T4 while opening, directly controls effect to output electric current.At this
Under state, the electric energy of E2 storage is discharged by T3, T4 and through output reactance device to source side, and output electric current forward direction increases, output
Current change quantity is determined by the end E2 voltage, power grid instantaneous voltage, output current-limiting reactor and S5 state duration.
Three above transient current control expression formula definitely characterize output electric current variation, each control formula again with change
The working condition for flowing device corresponds, this, which sufficiently shows, realizes the section directly controlled to output transient current by switch state
Learn reasonability.
2, the I type three-level current transformer topology significant instant current displacement factor and its function analysis
It is further processed, defines defeated in the unit time by current change quantity is exported under each effective working condition of above-mentioned release
The moving distance of electric current is transient current shift factor out, is denoted as δ iC, correspondingly obtain one group about transient current shift factor
Expression formula, each transient current shift factor is illustrated the control action of electric current separately below.
A, transient current shift factor δ i when current transformer works in S1 stateC_rpAre as follows:
δiC_rp(t)=[udc1(t)-uS(t)]/LC (4)
Formula (4) shows that exporting electric current at this time is positive and is in increase tendency, and electric current forward direction increase depends on the instantaneous electricity
Flow the action time of shift factor.
B, transient current shift factor δ i when current transformer works in S3 stateC_rnAre as follows:
δiC_rn(t)=- uS(t)/LC (5)
Formula (5) numerical value is to network voltage polarity on the contrary, corresponding present in network voltage negative half period of output electric current increases, in electricity
Reduced trend is presented in net voltage positive half cycle, when the amount that electric current increases or reduces depends on the effect of the transient current shift factor
Between.
Formula (5) shows that exporting electric current at this time is negative and still inversely increases, T1 shutdown, after the conducting of T2 pipe i.e. effectively, electric current
The amount of inversely increasing depends on the action time of the transient current shift factor.
C, transient current shift factor δ i when current transformer works in S5 stateC_dpAre as follows:
δiC_dp(t)=- [udc(t)+uS(t)]/LC (6)
Formula (6) shows that exporting electric current at this time is negative, and reduces trend, and electric current reduction amount is displaced depending on the transient current
The action time of the factor.
In regulation cycle TSSufficiently small, DC bus capacitor device E1, E2 Capacity Selection is rationally and output reactance device LCDo not satisfy
With in the case where it is considered that in a TSU in perioddc、uSAnd LCIt remains unchanged, i.e., each transient current shift factor is in a TS
It is constant in period.The current change quantity Δ i within any specific modulation periodCDepend entirely on current displacement factor delta iCWork
With time t, it is denoted as:
ΔiC=δ iC* t, t ∈ (0, tS) (13)
As known Δ iCAnd the selected δ i neededCAfterwards, it can be easy to calculate corresponding action time t and pass through pulsewidth
Modulation means realize control.
In conclusion there are three types of different transient current shift factors for exporting electric current for three level grid-connected converter of I type
It is selected when control, this is the difference with two level topological structure essence.
3, the grid-connected converter of three level main circuit topological structure of I type exports the direct tracking and controlling method of transient current.
Regulate and control cycle T in a PWMSIt is interior, converter switches pipe T1 and T3, T2 and T4 complementation conducting.As shown in Fig. 2, logical
Crossing real-time sampling can get k moment current transformer reality output transient current i (k), if k+1 moment expectation electric current value is i* (k+1),
The task of current follow-up control is exactly to make transient current i (k) by the selection to transient current shift factor and its action time
Through TSTime is transferred to i* (k+1).The practical realization that transient current directly controls is exactly to select appropriately within each regulation period
Each switching tube PWM pulse-width control signal.
3.1 outputs electric current i (k) are non-negative, output voltage u (k) is non-negative
In a TSWill be there are two effective shift factor alternating action in period, and only have shift factor in ascent stage and be
δiC_rpWhen meet the requirements, in decline stage shift factor δ iC_dpWith δ iC_rnIt is all satisfied requirement, the displacement for selecting pulsation of current small
Factor delta iC_rn.Assuming that δ iC_rpAction time t12onIt is t for switch transistor T 1, T2 service time12on, δ iC_rnAction time
t23onThat is switch transistor T 2, T3 turn-on time.It is available:
δiC_rp*t12on+δiC_rn*t23on=i (k+1)-i (k)
Wherein t12on+t23on=TS
To acquire:
t2on=Ts
3.2 outputs electric current i (k) are negative, output voltage u (k) is non-negative
Effective exciting current shift factor is followed successively by δ iC_rnWith δ iC_rp, action time respectively correspond T1, T2 open and T2,
T3 is open-minded.It is available:
t2on=Ts
3.3 outputs electric current i (k) are non-negative, output voltage u (k) is negative
In a TSSelect the significant instant current displacement factor for δ i in periodC_rnWith δ iC_dp, action time respectively corresponds
T2, T3 are opened and T3, T4 are open-minded.At this time within the entirely regulation period, switch transistor T 3 is constantly on, i.e., switch transistor T 1 is closed always
It closes.It is available:
t1on=0；
Electric current i (k) is negative, output voltage u (k) is negative for 3.4 outputs
In a TSSelect the significant instant current displacement factor for δ i in periodC_dpWith δ iC_rn, it is open-minded to respectively correspond T3, T4
And T2, T3 are open-minded.T3 is constantly within the entirely regulation period at this time, i.e. T1 pipe is closed always.It can obtain:
t1on=0；
Further, the pulse width calculation method of each switching tube can be unified are as follows:
As network voltage Us >=0, the pulse width of each switching tube are as follows:
t2on=Ts
t4on=0
As network voltage UsWhen < 0, the pulse width of each switching tube are as follows:
t1on=0
t3on=Ts
In formula:
Wherein, udc1、udc2For the end current transformer DC bus capacitor device E1, E2 voltage；uSFor network voltage；LCFor series reactance
Device；I (k) is k moment current transformer reality output transient current, and i (k+1) is k+1 moment expectation electric current value；TsTo regulate and control the period；
t1on、t2on、t3on、t4onRespectively switch transistor T 1, T2, T3, T4 PWM driving pulse width.
In practical application, on piece PWM peripheral functionality is carried by starting DSP main control chip, according to scheduled current regulation
Cycle TSPWM is set and regulates and controls cycle parameter, pwm pulse width is set by the calculated result of the pulse width of each switching tube, under
DSP intervention is not needed in one regulation period, PWM peripheral hardware will be automatically performed control to converter switches state, make output electricity
The variation of trace command electric current is flowed, the transient current for completing a cycle directly controls process.
If taking TS=100 μ s only need DSP data of every 100 μ s sampled operational, current transformer PWM arteries and veins after adopting this method
Rushing width theoretically can be in section [0, TS] on value；And use conventional current timing when comparing control method, if every 100 μ s into
Row primary current compares, and actually available pulse width can only be in set (0, TS) in value.Obviously, method proposed by the present invention
It all has an enormous advantage than conventional method in Project Realization difficulty and control precision.
Three-level current transformer traditional control method mostly uses space vector modulation, carrier modulation and particular harmonic to eliminate modulation
Etc. some synthesis PWM methods.And the present invention has found three for the grid-connected converter research of I type three-level topology structure
The significant instant current displacement factor, and a kind of transient current direct control method is proposed accordingly, there is clear concept, calculation amount
Small, pulsewidth utilization rate is high, the regulation feature performance benefits such as precisely.
4, simulating, verifying
To verify the effective of the three direct tracking and controlling method of level grid-connected converter transient current of I type proposed by the present invention
Property, simulating, verifying is carried out using Matlab/Simulink, artificial circuit is as shown in Figure 3.
Artificial circuit major parameter is provided that
Three-phase electricity voltage on line side is 380V, frequency 50Hz；DC side battery pack voltage rating 700V exports series reactance
Device 0.5mH, DC bus capacitor parameter 3360uF, proportionality constant Kp are 0.6, and integral constant Ki is 0.2, sampling period 100s.
Three level grid-connected converter output current wave quality verification of 4.1I type
Fig. 4 is the three level grid-connected converter output current wave of I type using this method；Fig. 5 is outlet side current spectrum
Analyze result.As can be seen that three-phase exports current first harmonics peak value 49.1A, fundamental wave virtual value about 34.7A, current waveform distortion rate
About 2.24%, reach preferable output current wave quality.
Three level grid-connected converter Bidirectional variable-flow performance verification of 4.2I type
Two-way four-quadrant unsteady flow function is the typical performance characteristic of grid-connected converter, thus specially to side proposed by the invention
The Bidirectional variable-flow performance of method has carried out simulating, verifying, as a result as shown in Figure 6, Figure 7 respectively.Fig. 6 show current transformer and works in PWM
Voltage/current waveform under (DC side battery charging) state of rectification, Fig. 7, which show current transformer and works in, to generate electricity by way of merging two or more grid systems
Voltage/current waveform under (electric discharge of DC side battery group) state.It can be proved that this method fully meets grid-connected converter pair
Functional requirement to unsteady flow.
The verifying of 4.3I type three-level current transformer output voltage waveforms
The three direct tracking and controlling method of level grid-connected converter transient current of I type proposed by the invention with it is traditional various
Three-level control principle method is from basic conception and realizes in step there is essential distinction, is the verifying present invention to I type three-level topology
The applicability of structure has carried out simulating, verifying to using the I type three-level current transformer output voltage waveforms of this method.Fig. 8 is to become
Flow device output line voltage waveform diagram.As can be seen that the I type three-level current transformer output line voltage waveform using this method accords with completely
Close traditional three-level current transformer characteristic feature.It can be proved that complete applicability of the present invention to I type three-level topology structure.
It can be seen from the above description that the application the above embodiments realize following technical effect:
The present invention is directed to I type three level grid-connected converter topological features, its normal operating conditions of analysis and summary and
Effective output state pushes away card and has obtained three effective transient current shift factor expression formulas and analyzed it to output state
Incentive action further pushes away card has obtained the realization three direct tracing control of level grid-connected converter transient current of I type one accordingly
As property PWM pulsewidth calculation formula, completely illustrate the base of the three direct tracking and controlling method of level grid-connected converter transient current of I type
Present principles and realization process.Using Matlab/Simulink simulation results show correct, validity of the invention.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention
The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.
Claims (9)
1. a kind of three direct tracking and controlling method of level grid-connected converter transient current of I type, which is characterized in that including following step
It is rapid:
Voltage, each phase voltage instantaneous value of power grid and current transformer at each regulation period real-time sampling current transformer DC bus capacitor device end
Actual output current instantaneous value；
For the different working condition of three level grid-connected converter of I type, excitation of each effective working condition to output electric current is analyzed
Effect calculates and generates each transient current shift factor；
Each phase is utilized by the significant instant current displacement factor in the mutually selection regulation period according to each real-time polarity of phase network voltage
Current expected value, actual value and the selected significant instant current displacement factor, calculate each significant instant current displacement factor
Action time and each switching tube PWM control pulse width, by pulsewidth modulation realize to current transformer export transient current it is straight
Connect control.
2. the three direct tracking and controlling method of level grid-connected converter transient current of I type according to claim 1, feature exist
In in a PWM regulation cycle TSIt is interior, the conducting complementary with switch transistor T 3 of the switch transistor T 1 of three level grid-connected converters, switching tube
T2 conducting complementary with switch transistor T 4, switch transistor T 1 to T4 are sequentially connected, the working condition of the current transformer are as follows:
S1=(switch transistor T 1 is open-minded, and switch transistor T 2 is open-minded, and switch transistor T 3 turns off, and switch transistor T 4 turns off)；
S2=(switch transistor T 1 turns off, and switch transistor T 2 is open-minded, and switch transistor T 3 turns off, and switch transistor T 4 turns off)；
S3=(switch transistor T 1 turns off, and switch transistor T 2 is open-minded, and switch transistor T 3 is open-minded, and switch transistor T 4 turns off)；
S4=(switch transistor T 1 turns off, and switch transistor T 2 turns off, and switch transistor T 3 is open-minded, and switch transistor T 4 turns off),
S5=(switch transistor T 1 turns off, and switch transistor T 2 turns off, and switch transistor T 3 is open-minded, and switch transistor T 4 is open-minded)；
Wherein, S1, S3, S5 are effective working condition, and S2, S4 are the transition state of experience of effective working condition transition period.
3. the three direct tracking and controlling method of level grid-connected converter transient current of I type according to claim 2, feature exist
In the calculation method of output current change quantity under each effective working condition are as follows:
In t moment, sampling end capacitor E1 end voltage on DC side is udc1(t), network voltage uS(t), output electric current is ic
(t), output current-limiting reactor inductance is LC；
When current transformer works in S1 state, T1, T2 pipe are simultaneously turned on, and the shutdown of T3, T4 pipe, T1, T2 pipe constant conduction time is
t12on, when showing that current transformer works in S1 state, export current change quantity Δ iC_rpAre as follows:
ΔiC_rp(t+t12on)={ [udc1(t)-uS(t)]/LC}*t12on
When current transformer works in S3 state, T2, T3 pipe are simultaneously turned on, and T1, T4 pipe shutdown, T2, T3 pipe turn-on time are t23on, obtain
When current transformer works in S3 state out, current change quantity Δ i is exportedC_rnAre as follows:
ΔiC_rn(t+t23on)=- { uS(t)/LC}*t23on
When current transformer works in S5 state, T3, T4 pipe are simultaneously turned on, and the shutdown of T1, T2 pipe, T3, T4 manage common turn-on time and be
t34on, when showing that current transformer works in S5 state, export current change quantity Δ iC_dpAre as follows:
ΔiC_dp(t+t34on)=- { [udc2(t)+uS(t)]/LC}*t34on。
4. the three direct tracking and controlling method of level grid-connected converter transient current of I type according to claim 2, feature exist
In the expression formula of transient current shift factor under each effective working condition are as follows:
Transient current shift factor δ i when current transformer works in S1 stateC_rpAre as follows:
δiC_rp=(udc1-uS)/LC
Transient current shift factor δ i when current transformer works in S3 stateC_rnAre as follows:
δiC_rn=-uS/LC
Transient current shift factor δ i when current transformer works in S5 stateC_dpAre as follows:
δiC_dp=-(udc2+uS)/LC
In formula, udc1、udc2The respectively upper and lower capacitor end voltage of DC side, uSFor grid side phase voltage, LCTo export series electrical
Anti- device inductance.
5. the three direct tracking and controlling method of level grid-connected converter transient current of I type according to claim 1, feature exist
Be equal in the action time of, the transient current shift factor one modulation period TSInterior current change quantity Δ iCWith electric current position
Move factor delta iCRatio.
6. the three direct tracking and controlling method of level grid-connected converter transient current of I type according to claim 4, feature exist
In the calculation method of the action time of the transient current shift factor are as follows:
Sampling k moment current transformer reality output transient current is i (k), if k+1 moment expectation electric current value is i (k+1)；
When export electric current i (k) it is non-negative, output voltage u (k) is non-negative when, one modulation period TSInterior selection significant instant electric current position
The shifting factor is δ iC_rnWith δ iC_rp, δ iC_rpAction time t12onFor switch transistor T 1, T2 service time, δ iC_rnAction time
t23onI.e. switch transistor T 2, T3 turn-on time, can obtain:
t2on=Ts
When output electric current i (k) be negative, output voltage u (k) be it is non-negative when, one modulation period TSInterior selection significant instant electric current
Shift factor is δ iC_rnWith δ iC_rp, δ iC_rpAction time t12onFor switch transistor T 1, T2 service time, δ iC_rnAction time
t23onFor switch transistor T 2, the turn-on time of T3, can obtain:
t2on=Ts
t2onPulse width is controlled for the PWM of switch transistor T 2；
When output electric current i (k) be it is non-negative, when output voltage u (k) is negative, one modulation period TSInterior selection significant instant displacement
The factor is δ iC_rnWith δ iC_dp, δ iC_rnAction time t23onFor switch transistor T 2, T3 service time, δ iC_dpAction time t34on
For switch transistor T 3, the turn-on time of T4, in modulation period TSInterior switch transistor T 3 is constantly on, and switch T1 pipe is closed always, can
:
t1on=0；
t1onPulse width is controlled for the PWM of switch transistor T 1；
When output electric current i (k) be negative, when output voltage u (k) is negative, one modulation period TSThe displacement of interior selection significant instant because
Son is δ iC_dpWith δ iC_rn, δ iC_rnAction time t23onFor switch transistor T 2, T3 service time, δ iC_dpAction time t34onFor
The turn-on time of switch transistor T 3, T4, in modulation period TSInterior switch transistor T 3 is constantly on, and switch T1 pipe is closed always, can obtain:
t1on=0；
7. the three direct tracking and controlling method of level grid-connected converter transient current of I type according to claim 3, feature exist
In the calculation method of the PWM control pulse width of each switching tube are as follows:
When network voltage Us > 0, the PWM control pulse width t of switch transistor T 1, T2, T3 and T41on、t2on、t3on、t4onIt is respectively as follows:
t2on=Ts
t4on=0
As network voltage Us< 0, the PWM control pulse width t of switch transistor T 1, T2, T3 and T41on、t2on、t3on、t4onIt is respectively as follows:
t1on=0
t3on=Ts
In formula:
Wherein, udc1、udc2For the end current transformer DC bus capacitor device E1, E2 voltage；uSFor network voltage；LCFor current-limiting reactor electricity
Sensibility reciprocal；I (k) is k moment current transformer reality output transient current, and i (k+1) is k+1 moment expectation electric current value；TsFor regulation week
Phase.
8. the three direct tracking and controlling method of level grid-connected converter transient current of I type according to claim 1, feature exist
In described realized by pulsewidth modulation exports the method that transient current directly controls to current transformer are as follows:
Start DSP and carry on piece PWM peripheral functionality, according to scheduled current regulation cycle TSPWM is set and regulates and controls cycle parameter, root
Each PWM time register is set according to the PWM control pulse width of each switching tube, is realized by PWM peripheral hardware to converter switches shape
State control makes to export the variation of current tracking instruction current.
9. a kind of computer installation, for realizing the three direct tracing control of level grid-connected converter transient current of I type, including storage
Device, processor and storage on a memory and the computer program that can run on a processor, the processor execution journey
Following steps are realized when sequence, comprising:
Sample current transformer DC bus capacitor device end voltage, each phase power grid instantaneous voltage and current transformer reality output transient current；
The different working condition of three level grid-connected converters is analyzed, calculates and exports curent change under each effective working condition
Amount and transient current shift factor；
Each phase current is utilized by the significant instant current displacement factor in the mutually selection regulation period according to each phase network voltage polarity
Desired value, actual value and the selected significant instant current displacement factor, calculate the work of each significant instant current displacement factor
Pulse width is controlled with the PWM of time and each switching tube, realizes that exporting transient current to current transformer directly controls by pulsewidth modulation
System.
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| CN102111083A (en) * | 2011-03-17 | 2011-06-29 | 株洲南车时代电气股份有限公司 | Dead-time effect simulation modeling device of three-level inverter and method thereof |
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| CN102684532A (en) * | 2012-04-23 | 2012-09-19 | 华为技术有限公司 | Three-level inverter |
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| CN102013825A (en) * | 2010-11-30 | 2011-04-13 | 中国南方电网有限责任公司电网技术研究中心 | Loss analysis method for diode clamping type three-level voltage source converter (VSC) |
| CN102111083A (en) * | 2011-03-17 | 2011-06-29 | 株洲南车时代电气股份有限公司 | Dead-time effect simulation modeling device of three-level inverter and method thereof |
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