CN105897030A - Dead beat fixed frequency model forecast control method, device and system - Google Patents

Abstract

The invention discloses a dead beat fixed frequency model forecast control method, device and system, and belongs to the technical field of photovoltaic power generation conversion control. The method comprises the following steps of obtaining values of output reference currents i<*><Alpha>(k+1) and i<*><Beta>(k+1) of a three-phase voltage inverter under a AlphaBeta coordinate system at the (k+1) moment through calculation; obtaining output reference currents u<*><Alpha>(k) and u<*><Beta>(k) of the three-phase voltage inverter under the AlphaBeta coordinate system at the k moment by calculation; taking two voltage vectors of a sector where the encircled reference voltage vector is located as a first action vector and a second action vector and a zero vector as a third action vector according to the sector where the reference voltage vector u<*><ref>(k)=u<*><Alpha>(k)+ju<*><Beta>(k) is located; and obtaining action time t1 of the first action vector, action time t2 of the second action vector and action time t0 of the third action vector by calculation. By the method, the advantages of model forecast and dead beat control are combined, the output voltage and the current frequency spectrum of the inverter are concentrated at integer multiples of switching frequency, and the design of an output filter is facilitated.

Description

A kind of dead beat frequency model predictive control method, Apparatus and system surely

Technical field

The present invention relates to photovoltaic generation Variable flow control technical field, be specifically related to a kind of dead beat frequency Model Predictive Control surely Method, Apparatus and system.

Background technology

Along with economic fast development and the pollution day by day of environment, the demand of regenerative resource is increased by the mankind day by day.Mesh Before, the development and utilization of regenerative resource obtains the attention of national governments.In regenerative resource development and utilization, inverter is made The bridge being connected with electrical network or load for renewable energy power generation (wind-power electricity generation, solar electrical energy generation etc.), is development of renewable energy The core of electricity, its performance directly affects whole renewable energy system.For the control of three-phase voltage-type inverter, conventional Method has quasi-resonance control, current hysteresis-band control, dead beat control under the proportional plus integral control under rotating coordinate system, rest frame System etc..But under proportional plus integral control method under rotating coordinate system and rest frame there is inverter in quasi-resonance control method Performance is relevant to the parameter of controller waits deficiency.And proportional plus integral control parameter and quasi-resonance control selection and the designer of parameter Experience be correlated with, the selection of its parameter will be through substantial amounts of experiment.The current hysteresis-band control of voltage source inverter is simple and is System has good dynamic property, but inverter output voltage, current spectrum ratio are relatively decentralized, are unfavorable for the design of output filter. Deadbeat Control Inverter has good dynamic property.But system is more sensitive to filtering parameter, robustness is poor.

In recent years, along with microelectric technique and the development of digital signal processor, Model Predictive Control becomes at power electronics Parallel operation is widely used.Converters or motor driver can be defined as how going to select suitable gate pole Drive control signal S (t), makes variable x (t) of control system go close to desired reference variable x as far as possible^*(t).Assuming that system Sampling period be T_s, system variable x (t) is at t_kMoment value is x (t_k).If system exists n controlling behavior, and n is limited.Mould Type PREDICTIVE CONTROL makes full use of the discretization feature of converters, fully takes into account the limited kind of converters On off state (converters has particular kind of switch combination).Model Predictive Control with an object function to often A kind of behavior (switch combination of converters) predicts the outcome and carries out online evaluation, and it is minimum that selection can meet object function The switches set incompatible realization control to converters.As Chile Rodriguez professor R should by Model Predictive Control For two level grid-connected inverters, many level grid-connected inverters, AC Motor Control, uninterrupted power source (UPS), matrix form conversion Deng, obtain the most quiet, dynamic property.The not enough inverter output voltage of Model Predictive Control maximum, current spectrum ratio are relatively decentralized, The difficult design of inverter filtering device.

Summary of the invention

Therefore, the embodiment of the present invention to solve the technical problem that the inverter output being current model predictive control method Voltage, current spectrum ratio are relatively decentralized, the difficult design of output filter.

To this end, a kind of dead beat of embodiment of the present invention frequency model predictive control method surely, comprise the following steps:

Calculate to obtain and under k+1 moment three-phase voltage-type inverter α β coordinate system, export reference currentWith Value；

According to formulaCalculate and obtain k moment three-phase voltage-type inverter α Output reference voltage under β coordinate systemWithWherein, i_α(k) and i_βK () is respectively k moment three-phase voltage type inversion Device output electric current α, β component under α β coordinate system, R is load resistance, T_sFor the sampling period, L is filter inductance value；

According to reference voltage vectorResiding sector, will surround reference voltage vector Two voltage vectors of residing sector act on vector as the first effect vector second, are vowed as the 3rd effect by zero vector Amount, wherein, obtains the voltage space arrow that α β plane marks off sector according to the switch combination of three-phase voltage-type inverter output Amount, space vector of voltage includes voltage vector and zero vector；

According to formulaCalculate the work obtaining the first effect vector Use time t₁, second effect vector t action time₂T action time with the 3rd effect vector₀, its In, g₁、g₂And g₀Be respectively the first effect vector, the second effect vector the 3rd acts on the target function value that vector is corresponding,Wherein, u_αm(k) and u_βmK () is respectively k moment m Effect vector α, β component under α β coordinate system, m=0,1,2.

Preferably, described output reference currentWithCalculated by linear interpolation theorem and obtain, calculate public affairs Formula is as follows:

Wherein,WithPoint Wei k moment, k-1 moment and the output reference current in k-2 moment.

Preferably, described space vector of voltage is the space vector of voltage that α β plane marks off six sectors, including voltage Vector u_nWith zero vector u₀、u₇, n=1,2 ..., 6；

$u_n=\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}n}\\ u_{\mathrm{\&beta;}n}\end{array}\right]=V_{dc}{C}_{3/2}{S}_n$

Wherein, u_αnAnd u_βnIt is respectively voltage vector u_nα, β component under α β coordinate system, V_dcFor DC bus-bar voltage,For transformation matrix,S_a、S_bAnd S_cRepresent a, b and c phase respectively On off state.

Preferably, described reckoning obtains output reference current under k+1 moment three-phase voltage-type inverter α β coordinate systemWithValue step before, further comprising the steps of:

Obtain k moment three-phase voltage-type inverter output electric current under three phase static abc coordinate system；

The α component i that output electric current under three phase static abc coordinate system is converted under α β coordinate system_α(k) and β component i_β (k)。

A kind of dead beat of embodiment of the present invention frequency model predictive control apparatus surely, including:

First computing unit, is used for calculating that under acquisition k+1 moment three-phase voltage-type inverter α β coordinate system, output is with reference to electricity StreamWithValue；

Second computing unit, for according to formulaCalculate and obtain the k moment Output reference voltage under three-phase voltage-type inverter α β coordinate systemWithWherein, i_α(k) and i_βK () is respectively k Moment three-phase voltage-type inverter output electric current α, β component under α β coordinate system, R is load resistance, T_sFor sampling period, L For filter inductance value；

Effect vector determination unit, for according to reference voltage vectorResiding fan Surround sector residing for reference voltage vector two voltage vectors are acted on vector as the first effect vector second by district, will Zero vector is as the 3rd effect vector, wherein, obtains according to the switch combination of three-phase voltage-type inverter output and is drawn by α β plane Separating the space vector of voltage of sector, space vector of voltage includes voltage vector and zero vector；

Action time obtains unit, for according to formulaCalculate Obtain t action time of the first effect vector₁, second effect vector t action time₂Action time with the 3rd effect vector t₀, wherein, g₁、g₂And g₀Be respectively the first effect vector, the second effect vector the 3rd acts on the object function that vector is corresponding Value, Wherein, u_αm(k) and u_βmK () is respectively the k moment M effect vector α, β component under α β coordinate system, m=0,1,2.

Preferably, described output reference currentWithCalculated by linear interpolation theorem and obtain, calculate public affairs Formula is as follows:

Wherein,WithPoint Wei k moment, k-1 moment and the output reference current in k-2 moment.

Preferably, described space vector of voltage is the space vector of voltage that α β plane marks off six sectors, including voltage Vector u_nWith zero vector u₀、u₇, n=1,2 ..., 6；

$u_n=\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}n}\\ u_{\mathrm{\&beta;}n}\end{array}\right]=V_{dc}{C}_{3/2}{S}_n$

Wherein, u_αnAnd u_βnIt is respectively voltage vector u_nα, β component under α β coordinate system, V_dcFor DC bus-bar voltage,For transformation matrix,S_bAnd S_cRepresent a, b and c phase respectively On off state.

Preferably, before described first computing unit, also include:

Acquiring unit, for obtaining k moment three-phase voltage-type inverter output electricity under three phase static abc coordinate system Stream；

Coordinate transformation unit, for dividing the α that the output electric current under three phase static abc coordinate system is converted under α β coordinate system Amount i_α(k) and β component i_β(k)。

A kind of dead beat of embodiment of the present invention frequency model predictive control system surely, including: three-phase voltage-type inverter and Above-mentioned dead beat frequency model predictive control apparatus surely；

Three-phase voltage-type inverter, its input is connected with the outfan of regenerative resource, and it is fixed with dead beat that it controls end Frequently the outfan of model predictive control apparatus connects；

Dead beat frequency model predictive control apparatus surely, for generating the first effect vector controlling three-phase voltage-type inverter T action time₁, second effect vector t action time₂T action time with the 3rd effect vector₀。

The technical scheme of the embodiment of the present invention, has the advantage that

1. the dead beat that the embodiment of the present invention provides frequency model predictive control method, Apparatus and system surely, by using k+1 Moment output reference currentWithCalculate k moment output reference voltageWithI.e. according to inverse Become device set-point and the deviation of actual value, realize the tracking to set-point in next one sampling, it is achieved that track with zero error, and Inverter output voltage, current spectrum concentrate on the integral multiple of switching frequency, thus combine model prediction and track with zero error Advantage, system has the most quiet, dynamic property, is also beneficial to the design of output filter.And use three effect vectors It is predicted the calculating of model and object function, greatly reduces calculation times, improve computational efficiency.

Accompanying drawing explanation

In order to be illustrated more clearly that the specific embodiment of the invention or technical scheme of the prior art, below will be to specifically In embodiment or description of the prior art, the required accompanying drawing used is briefly described, it should be apparent that, in describing below Accompanying drawing is some embodiments of the present invention, for those of ordinary skill in the art, before not paying creative work Put, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the flow chart of a dead beat concrete example of frequency model predictive control method surely in the embodiment of the present invention 1；

Fig. 2 is the space vector of voltage graph of a relation marking off six sectors；

Fig. 3 is the structure chart of three-phase voltage type contravariant generating system；

Fig. 4 is action time and the precedence diagram that reference voltage vector respectively acts on vector when I sector；

Fig. 5 is the dead beat frequency Model Predictive Control policy map surely of three-phase voltage-type inverter；

Fig. 6 is the principle frame of a dead beat concrete example of frequency model predictive control apparatus surely in the embodiment of the present invention 2 Figure；

Fig. 7 is the principle frame of a dead beat concrete example of frequency model predictive control system surely in the embodiment of the present invention 3 Figure.

Detailed description of the invention

Below in conjunction with accompanying drawing, technical scheme is clearly and completely described, it is clear that described enforcement Example is a part of embodiment of the present invention rather than whole embodiments.Based on the embodiment in the present invention, ordinary skill The every other embodiment that personnel are obtained under not making creative work premise, broadly falls into the scope of protection of the invention.

In describing the invention, it should be noted that term " first ", " second " etc. are not only used for describing purpose, and not It is understood that as instruction or hint relative importance.

If additionally, the most non-structure of technical characteristic involved in invention described below difference embodiment Become conflict just can be combined with each other.

Embodiment 1

The present embodiment provides a kind of dead beat frequency model predictive control method surely, for example, it is possible to be applied to three-phase voltage type Contravariant generating system, as it is shown in figure 1, the method comprises the following steps:

S1, reckoning obtain and export reference current under k+1 moment three-phase voltage-type inverter α β coordinate systemWithValue；

S2, according to formulaCalculate acquisition k moment three-phase voltage type inverse Become output reference voltage under device α β coordinate systemWithWherein, i_α(k) and i_βK () is respectively k moment three-phase voltage Type inverter output current α, β component under α β coordinate system, R is load resistance, T_sFor the sampling period, L is filter inductance value；

S3, according to reference voltage vectorResiding sector, will surround reference voltage Two voltage vectors of sector residing for vector act on vector as the first effect vector second, using zero vector as the 3rd effect Vector, wherein, obtains the voltage space that α β plane marks off sector according to the switch combination of three-phase voltage-type inverter output Vector, space vector of voltage includes voltage vector and zero vector；

S4, according to formulaCalculate and obtain the first effect vector Action time t₁, second effect vector t action time₂T action time with the 3rd effect vector₀, wherein, g₁、g₂ And g₀Be respectively the first effect vector, the second effect vector the 3rd acts on the target function value that vector is corresponding,Wherein, u_αm(k) and u_βmK () is respectively k moment m Effect vector α, β component under α β coordinate system, m=0,1,2.

Above-mentioned dead beat frequency model predictive control method surely, by using the k+1 moment to export reference currentWithCalculate k moment output reference voltageWithI.e. according to inverter set-point and the deviation of actual value, The tracking to set-point is realized, it is achieved that track with zero error, and inverter output voltage, current spectrum collection in next one sampling In at the integral multiple of switching frequency, thus combine the advantage of model prediction and track with zero error, system has the most quiet, dynamic Performance, is also beneficial to the design of output filter.And use three effect vectors to be predicted the meter of model and object function Calculate, greatly reduce calculation times, improve computational efficiency.

Preferably, output reference currentWithBeing calculated by linear interpolation theorem and obtain, computing formula is such as Under:

Wherein,WithPoint Wei k moment, k-1 moment and the output reference current in k-2 moment.

Preferably, space vector of voltage is the space vector of voltage that α β plane marks off six sectors, space vector of voltage Relation is as in figure 2 it is shown, it includes voltage vector u_nWith zero vector u₀、u₇, n=1,2 ..., 6；Six sectors are expressed as sector Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ。

$u_n=\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}n}\\ u_{\mathrm{\&beta;}n}\end{array}\right]=V_{dc}{C}_{3/2}{S}_n$

Wherein, u_αnAnd u_βnIt is respectively voltage vector u_nα, β component under α β coordinate system, V_dcFor DC bus-bar voltage,For transformation matrix,S_a、S_bAnd S_cRepresent a, b and c phase respectively On off state.

Preferably, before step S1, further comprising the steps of:

S0-1, acquisition k moment three-phase voltage-type inverter output electric current under three phase static abc coordinate system；

S0-2, the α component i that the output electric current under three phase static abc coordinate system is converted under α β coordinate system_αK () and β divide Amount i_β(k)。

Above-mentioned dead beat frequency model predictive control method surely, by first obtaining under three-phase voltage-type inverter abc coordinate system Output electric current, the most again the output electric current under this abc coordinate system is converted into α, β component under α β coordinate system, for follow-up meter Calculate and use, owing to the acquisition of the output electric current under abc coordinate system is relatively easy, calculates such that it is able to simplify, improve treatment effeciency.

It is described in detail as a example by a kind of concrete three-phase voltage type contravariant generating system below, the knot of this electricity generation system Structure is as shown in Figure 3.This electricity generation system is mainly by regenerative resource (such as photovoltaic, wind-powered electricity generation etc.), three-phase voltage-type inverter, L filtering Device, load R etc. are constituted.Regenerative resource can be by DC source E_dcWith direct current input resistance R_dcEquivalence.

According to Kirchhoff's second law, its dynamic current equation is (current reference direction is as shown in Figure 3):

$L\frac{d}{dt}\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]=\left[\begin{array}{c}{u}_{aN}\\ u_{bN}\\ u_{cN}\end{array}\right]-\left[\begin{array}{c}{u}_{nN}\\ u_{nN}\\ u_{nN}\end{array}\right]-R\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]---\left(1\right)$

Wherein, i_a、i_b、i_cElectric current is exported for three-phase voltage-type inverter；u_aN、u_bN、u_cNDefeated for three-phase voltage-type inverter Go out voltage；R is load resistance；u_nNFor the voltage between neutral point and the negative pole of dc bus of line voltage.

In view of three-phase symmetrical system, then

i_a+i_b+i_c=0 (2)

Convolution (1) and (2) can obtain:

$u_{nN}=\frac{u_{aN}+u_{bN}+u_{cN}}{3}---\left(3\right)$

Convolution (1) and formula (3) can obtain:

$L\frac{d}{dt}\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]=\frac{1}{3}\left[\begin{array}{ccc}2& -1& -1\\ -1& 2& -1\\ -1& -1& 2\end{array}\right]\left[\begin{array}{c}{u}_{aN}\\ u_{bN}\\ u_{cN}\end{array}\right]-R\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]---\left(4\right)$

In order to the Transformation of Mathematical Model of three-phase voltage-type inverter three phase static abc coordinate system to biphase static α β coordinate In system, its transformation matrix C_3/2(constant power coordinate transform) and its inverse matrixIt is defined as follows:

$C_{3/2}=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\\ 1/\sqrt{2}& 1/\sqrt{2}& 1/\sqrt{2}\end{array}\right],C_{3/2}^{-1}=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& 0& 1/\sqrt{2}\\ -1/2& \sqrt{3}/2& 1/\sqrt{2}\\ -1/2& -\sqrt{3}/2& 1/\sqrt{2}\end{array}\right]---\left(5\right)$

Combinatorial formula (4) and formula (5) can obtain:

$\left\{\begin{array}{c}L\frac{{\mathrm{di}}_{\mathrm{\&alpha;}}}{dt}=u_a-{\mathrm{Ri}}_{\mathrm{\&alpha;}}\\ L\frac{{\mathrm{di}}_{\mathrm{\&beta;}}}{dt}=u_{\mathrm{\&beta;}}-{\mathrm{Ri}}_{\mathrm{\&beta;}}\end{array}\right.---\left(6\right)$

Wherein, i_α、i_βElectric current α, β component under α β coordinate system is exported for three-phase voltage-type inverter；u_α、u_βFor three-phase electricity Die mould inverter output voltage is α, β component under α β coordinate system.

Assuming that sampling period T_sFor smaller, by Euler's formula, formula (6) discretization can be obtained:

$\left\{\begin{array}{c}L\frac{i_{\mathrm{\&alpha;}}(k+1)-i_{\mathrm{\&alpha;}}\left(k\right)}{T_s}=u_a\left(k\right)-{\mathrm{Ri}}_{\mathrm{\&alpha;}}\left(k\right)\\ L\frac{i_{\mathrm{\&beta;}}(k+1)-i_{\mathrm{\&beta;}}\left(k\right)}{T_s}=u_{\mathrm{\&beta;}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\&beta;}}\left(k\right)\end{array}\right.---\left(7\right)$

At (k+1) moment three-phase voltage-type inverter predicted current it is then:

$\left\{\begin{array}{c}{i}_{\mathrm{\&alpha;}}(k+1)=\frac{T_s}{L}\&lsqb;u_a\left(k\right)-{\mathrm{Ri}}_{\mathrm{\&alpha;}}\left(k\right)\&rsqb;+i_{\mathrm{\&alpha;}}\left(k\right)\\ i_{\mathrm{\&beta;}}(k+1)=\frac{T_s}{L}\&lsqb;u_{\mathrm{\&beta;}}\left(k\right)-{\mathrm{Ri}}_{\mathrm{\&beta;}}\left(k\right)\&rsqb;+i_{\mathrm{\&beta;}}\left(k\right)\end{array}\right.---\left(8\right)$

Assuming that reach given electric current at (k+1) moment three-phase voltage-type inverter electric current, it is achieved track with zero error, i.e.

$\left\{\begin{array}{c}{i}_{\mathrm{\&alpha;}}(k+1)=i_{\mathrm{\&alpha;}}^{*}(k+1)\\ i_{\mathrm{\&beta;}}(k+1)=i_{\mathrm{\&beta;}}^{*}(k+1)\end{array}\right.---\left(9\right)$

And at (k+1) moment three-phase voltage-type inverter reference currentWithCan be by (k) moment, (k-1) Moment and (k-2) moment reference current can be obtained by linear interpolation theorem:

$\left\{\begin{array}{c}{i}_{\mathrm{\&alpha;}}^{*}(k+1)=3i_{\mathrm{\&alpha;}}^{*}\left(k\right)-3i_{\mathrm{\&alpha;}}^{*}(k-1)+i_{\mathrm{\&alpha;}}^{*}(k-2)\\ i_{\mathrm{\&beta;}}^{*}(k+1)=3i_{\mathrm{\&beta;}}^{*}\left(k\right)-3i_{\mathrm{\&beta;}}^{*}(k-1)+i_{\mathrm{\&beta;}}^{*}(k-2)\end{array}\right.---\left(10\right)$

In order to realize realizing given electric current track with zero error in the next sampling period, three-phase voltage-type inverter exports Reference voltage is:

$\left\{\begin{array}{c}{u}_{\mathrm{\&alpha;}}^{*}\left(k\right)=\frac{L}{T_s}\&lsqb;i_{\mathrm{\&alpha;}}^{*}(k+1)-i_{\mathrm{\&alpha;}}\left(k\right)\&rsqb;+{\mathrm{Ri}}_{\mathrm{\&alpha;}}\left(k\right)\\ u_{\mathrm{\&beta;}}^{*}\left(k\right)=\frac{L}{T_s}\&lsqb;i_{\mathrm{\&beta;}}^{*}(k+1)-i_{\mathrm{\&beta;}}\left(k\right)\&rsqb;+{\mathrm{Ri}}_{\mathrm{\&beta;}}\left(k\right)\end{array}\right.---\left(11\right)$

In any phase brachium pontis of three-phase voltage type inverter circuit, according to different switch combinations, can obtain following Two kinds of output states: " P " state and " N " state.As a example by a phase brachium pontis: (1) " P " state: now switching tube S_a1Conducting, switch Pipe S_a2Turning off, outfan a is relative to N point current potential u_aN=V_dc；(2) " N " state: switching tube S_a1Turn off, switching tube S_a2Conducting, defeated Go out to hold a relative to N point current potential u_aN=0.The output state of b, c phase brachium pontis is similar with a phase brachium pontis.According to three-phase voltage-type inverter The switch combination of output, three-phase voltage-type inverter produces 2 altogether³=8 voltage vectors, the size of its voltage vector and space Position is as shown in Figure 2.Assuming that variable S_a, S_b, S_c{ 1, the 0} on off state representing each phase, wherein " 1 " represents output and bus Positive polarity P point is connected, and " 0 " represents output and is connected with busbar voltage negative pole N point.The switch shape of three-phase voltage-type inverter output State S_j=[S_a S_b S_c]^T, wherein j=0 ..., 7.Then inverter output voltage voltmeter under static α β coordinate system is shown as:

$u_j=\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}j}\\ u_{\mathrm{\&beta;}j}\end{array}\right]=V_{dc}{C}_{3/2}{S}_j,(j=0,1,...,7)---\left(12\right)$

For realizing three-phase voltage-type inverter to given electric current accurate tracking, dead beat Model Predictive Control object function It is chosen as:

$g\left(k\right)=|u_{\mathrm{\&alpha;}}^{*}\left(k\right)-u_{\mathrm{\&alpha;}j}\left(k\right)|+|u_{\mathrm{\&beta;}}^{*}\left(k\right)-u_{\mathrm{\&beta;}j}\left(k\right)|---\left(13\right)$

From formula (11), formula (12) and formula (13), traditional model prediction needs to vow 8 voltages of inverter output Amount is predicted model and object function g (k) at line computation and online evaluation, and these 8 which voltage vectors of voltage vector make Object function is minimum, and this voltage vector will be used at next cycle, it is achieved the optimum control of target.Therefore, tradition Model Predictive Control will carry out 8 forecast models and the calculating of object function, for reducing forecast model and the meter of object function Calculate number of times, can be according to reference voltageLocus, participate in forecast model and object function and exist The voltage vector of line assessment be 3 closest to reference voltage vector (2 non-zero and 1 zero vector).Therefore, prediction is participated in The voltage vector of model and object function online evaluation greatly reduces, and is greatly improved the meter of limited on off state Model Predictive Control Calculate efficiency.The locus of reference voltage vector is:

$\mathrm{\&theta;}=artan\left(u_{\mathrm{\&beta;}}^{*}\right(k)/u_{\mathrm{\&alpha;}}^{*}(k\left)\right)---\left(14\right)$

Assuming that reference voltageIt is positioned at the Ith sector, then participate in forecast model and object function Voltage vector be u₁(100)、u₂(110)、u₀(000) (or u₇(111)).Zero vector u₀And u (000)₇(111) target produced Function is the same, therefore, participates in forecast model calculating and object function assessment has only to once.Compare, in advance with conventional model prediction The calculation times surveying model is reduced to 3 times by 8 times, greatly reduces amount of calculation, improves computational efficiency.For making inverter output electricity Pressure, the integral multiple of current spectrum centralizing switch frequency, it is assumed that reference voltageIt is positioned at the Ith sector, logical Cross formula (13), voltage vector u₁Object function be g₁, voltage vector u₂Object function be g₂, voltage vector u₀(or u₇) mesh Scalar functions is g₀。

Wherein,

Wherein,

Wherein,

According to three voltage vector object function g₁、g₂And g₀Action time of each voltage vector of size linear distribution.? One sampling period T_sIn, voltage vector u₁Action time be t₁, voltage vector u₂Action time be t₂, voltage vector u₀ (or u₇) action time be t₀, the action time of the most each vector is:

$\left\{\begin{array}{c}{t}_1=T_s(1/g_1)/\left(\right(1/g_1)+(1/g_2)+(1/g_0\left)\right)\\ t_2=T_s(1/g_2)/\left(\right(1/g_1)+(1/g_2)+(1/g_0\left)\right)\\ t_0=T_s(1/g_0)/\left(\right(1/g_1)+(1/g_2)+(1/g_0\left)\right)\\ T_s=T_s(t_0+t_1+t_2)\end{array}\right.---\left(15\right)$

In order to reduce three-phase voltage-type inverter output voltage, current harmonics further, it is preferable that each voltage vector effect Time symmetrical distribution；Meanwhile, voltage vector u₀And u₇Acting on, each voltage vector action time is half simultaneously.Reference voltage vectorWhen I sector, the action time of its each voltage vector and sequence of operation are as shown in Figure 4.

Other sectors the like.Compare with traditional Model Predictive Control, have 1 zero vector and 2 at a PWM cycle Individual non-zero effect, similar with 7 traditional segmentation SVPWM modulation, it is achieved inverter output voltage, electric current frequency surely, thus can To simplify the design of output filter.The dead beat of three-phase voltage-type inverter frequency Model Predictive Control strategy surely is as shown in Figure 5.

Embodiment 2

Corresponding to embodiment 1, the present embodiment provides a kind of dead beat frequency model predictive control apparatus surely, as shown in Figure 6, bag Include:

First computing unit 1, is used for calculating that under acquisition k+1 moment three-phase voltage-type inverter α β coordinate system, output is with reference to electricity StreamWithValue；

Second computing unit 2, for according to formulaWhen calculating acquisition k Carve output reference voltage under three-phase voltage-type inverter α β coordinate systemWithWherein, i_α(k) and i_βK () is respectively K moment three-phase voltage-type inverter output electric current α, β component under α β coordinate system, R is load resistance, T_sFor sampling period, L For filter inductance value；

Effect vector determination unit 3, for according to reference voltage vectorResiding Surround sector residing for reference voltage vector two voltage vectors are acted on vector as the first effect vector second by sector, Using zero vector as the 3rd effect vector, wherein, obtain α β plane according to the switch combination of three-phase voltage-type inverter output Marking off the space vector of voltage of sector, space vector of voltage includes voltage vector and zero vector；

Obtain unit 4 action time, for according to formulaCalculate Obtain t action time of the first effect vector₁, second effect vector t action time₂Action time with the 3rd effect vector t₀, wherein, g₁、g₂And g₀Be respectively the first effect vector, the second effect vector the 3rd acts on the object function that vector is corresponding Value, Wherein, u_αm(k) and u_βmK () is respectively the k moment M effect vector α, β component under α β coordinate system, m=0,1,2.

Above-mentioned dead beat frequency model predictive control apparatus surely, by using the k+1 moment to export reference currentWithCalculate k moment output reference voltageWithI.e. according to inverter set-point and the deviation of actual value, The tracking to set-point is realized, it is achieved that track with zero error, and inverter output voltage, current spectrum collection in next one sampling In at the integral multiple of switching frequency, thus combine the advantage of model prediction and track with zero error, system has the most quiet, dynamic Performance, is also beneficial to the design of output filter.And use three effect vectors to be predicted the meter of model and object function Calculate, greatly reduce calculation times, improve computational efficiency.

Preferably, output reference currentWithBeing calculated by linear interpolation theorem and obtain, computing formula is such as Under:

Wherein,WithPoint Wei k moment, k-1 moment and the output reference current in k-2 moment.

Preferably, space vector of voltage is the space vector of voltage that α β plane marks off six sectors, including voltage vector u_nWith zero vector u₀、u₇, n=1,2 ..., 6；

$u_n=\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}n}\\ u_{\mathrm{\&beta;}n}\end{array}\right]=V_{dc}{C}_{3/2}{S}_n$

Wherein, u_αnAnd u_βnIt is respectively voltage vector u_nα, β component under α β coordinate system, V_dcFor DC bus-bar voltage,For transformation matrix,S_a、S_bAnd S_cRepresent a, b and c phase respectively On off state.

Preferably, before the first computing unit 1, also include:

Acquiring unit, for obtaining k moment three-phase voltage-type inverter output electricity under three phase static abc coordinate system Stream；

Coordinate transformation unit, for dividing the α that the output electric current under three phase static abc coordinate system is converted under α β coordinate system Amount i_α(k) and β component i_β(k)。

Embodiment 3

The present embodiment provides a kind of dead beat frequency model predictive control system surely, as it is shown in fig. 7, comprises: three-phase voltage type The dead beat of inverter 10 and embodiment 2 frequency model predictive control apparatus 20 surely；

Three-phase voltage-type inverter 10, its input is connected with the outfan of regenerative resource, and it controls end and dead beat The outfan of fixed frequency model predictive control apparatus connects；

Dead beat frequency model predictive control apparatus 20 surely, vows for generating the first effect controlling three-phase voltage-type inverter T action time of amount₁, second effect vector t action time₂T action time with the 3rd effect vector₀。

Above-mentioned dead beat frequency model predictive control system surely, by using the k+1 moment to export reference currentWithCalculate k moment output reference voltageWithI.e. inclined according to inverter set-point and actual value Difference, realizes the tracking to set-point in next one sampling, it is achieved that track with zero error, and inverter output voltage, electric current frequency Spectrum concentrates on the integral multiple of switching frequency, thus combines the advantage of model prediction and track with zero error, system have the most quiet, Dynamic property, is also beneficial to the design of output filter.And use three effect vectors to be predicted model and object function Calculating, greatly reduce calculation times, improve computational efficiency.

Obviously, above-described embodiment is only for clearly demonstrating example, and not restriction to embodiment.Right For those of ordinary skill in the field, can also make on the basis of the above description other multi-form change or Variation.Here without also cannot all of embodiment be given exhaustive.And the obvious change thus extended out or Change among still in the protection domain of the invention.

Claims (9)

1. a dead beat frequency model predictive control method surely, it is characterised in that comprise the following steps:

Calculate to obtain and under k+1 moment three-phase voltage-type inverter α β coordinate system, export reference currentWithValue；

According to formulaCalculate and obtain k moment three-phase voltage-type inverter α β seat The lower output reference voltage of mark systemWithWherein, i_α(k) and i_βK () is respectively k moment three-phase voltage-type inverter Output electric current α, β component under α β coordinate system, R is load resistance, T_sFor the sampling period, L is filter inductance value；

According to reference voltage vectorResiding sector, will surround residing for reference voltage vector Two voltage vectors of sector act on vector as the first effect vector second, using zero vector as the 3rd effect vector, its In, the space vector of voltage that α β plane is marked off sector, electricity is obtained according to the switch combination of three-phase voltage-type inverter output Pressure space vector includes voltage vector and zero vector；

According to formulaWhen calculating the effect obtaining the first effect vector Between t₁, second effect vector t action time₂T action time with the 3rd effect vector₀, wherein, g₁、g₂ And g₀Be respectively the first effect vector, the second effect vector the 3rd acts on the target function value that vector is corresponding,Wherein, u_αm(k) and u_βmK () is respectively k moment m Effect vector α, β component under α β coordinate system, m=0,1,2.

Method the most according to claim 1, it is characterised in that described output reference currentWithPass through Linear interpolation theorem calculates and obtains, and computing formula is as follows:

Wherein,WithIt is respectively k The output reference current in moment, k-1 moment and k-2 moment.

Method the most according to claim 1 and 2, it is characterised in that described space vector of voltage is for mark off α β plane The space vector of voltage of six sectors, including voltage vector u_nWith zero vector u₀、u₇, n=1,2 ..., 6；

$u_n=\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}n}\\ u_{\mathrm{\&beta;}n}\end{array}\right]=V_{dc}{C}_{3/2}{S}_n$

Wherein, u_αnAnd u_βnIt is respectively voltage vector u_nα, β component under α β coordinate system, V_dcFor DC bus-bar voltage,For transformation matrix,S_a、S_bAnd S_cRepresent a, b and c phase respectively On off state.

4. according to the method described in any one of claim 1-3, it is characterised in that described reckoning obtains k+1 moment three-phase voltage Reference current is exported under type inverter α β coordinate systemWithValue step before, further comprising the steps of:

Obtain k moment three-phase voltage-type inverter output electric current under three phase static abc coordinate system；

The α component i that output electric current under three phase static abc coordinate system is converted under α β coordinate system_α(k) and β component i_β(k)。

5. a dead beat frequency model predictive control apparatus surely, it is characterised in that including:

First computing unit, is used for calculating output reference current under acquisition k+1 moment three-phase voltage-type inverter α β coordinate systemWithValue；

Second computing unit, for according to formulaCalculate and obtain k moment three-phase Output reference voltage under voltage source inverter α β coordinate systemWithWherein, i_α(k) and i_βK () is respectively the k moment Three-phase voltage-type inverter output electric current α, β component under α β coordinate system, R is load resistance, T_sFor the sampling period, L is filter Ripple inductance value；

Effect vector determination unit, for according to reference voltage vectorResiding sector, Surround sector residing for reference voltage vector two voltage vectors are acted on vector, by null vector as the first effect vector second Measure as the 3rd effect vector, wherein, obtain according to the switch combination of three-phase voltage-type inverter output and α β plane is marked off The space vector of voltage of sector, space vector of voltage includes voltage vector and zero vector；

Action time obtains unit, for according to formulaCalculate acquisition the T action time of one effect vector₁, second effect vector t action time₂T action time with the 3rd effect vector₀, its In, g₁、g₂And g₀Be respectively the first effect vector, the second effect vector the 3rd acts on the target function value that vector is corresponding, Wherein, u_αm(k) and u_βmK () is respectively k moment m Effect vector α, β component under α β coordinate system, m=0,1,2.

Device the most according to claim 5, it is characterised in that described output reference currentWithPass through Linear interpolation theorem calculates and obtains, and computing formula is as follows:

Wherein,WithIt is respectively k The output reference current in moment, k-1 moment and k-2 moment.

7. according to the device described in claim 5 or 6, it is characterised in that described space vector of voltage is for mark off α β plane The space vector of voltage of six sectors, including voltage vector u_nWith zero vector u₀、u₇, n=1,2 ..., 6；

$u_n=\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}n}\\ u_{\mathrm{\&beta;}n}\end{array}\right]=V_{dc}{C}_{3/2}{S}_n$

Wherein, u_αnAnd u_βnIt is respectively voltage vector u_nα, β component under α β coordinate system, V_dcFor DC bus-bar voltage,For transformation matrix,S_a、S_bAnd S_cRepresent a, b and c phase respectively On off state.

8. according to the device described in any one of claim 5-7, it is characterised in that before described first computing unit, also include:

Acquiring unit, for obtaining k moment three-phase voltage-type inverter output electric current under three phase static abc coordinate system；

Coordinate transformation unit, for the α component i being converted under α β coordinate system by the output electric current under three phase static abc coordinate system_α (k) and β component i_β(k)。

9. dead beat frequency model predictive control system surely, it is characterised in that including: three-phase voltage-type inverter and such as right Require the frequency model predictive control apparatus surely of the dead beat described in any one of 5-8；

Three-phase voltage-type inverter, its input is connected with the outfan of regenerative resource, and it controls end and dead beat frequency mould surely The outfan of type prediction control device connects；

Dead beat frequency model predictive control apparatus surely, for generating the work of the first effect vector controlling three-phase voltage-type inverter Use time t₁, second effect vector t action time₂T action time with the 3rd effect vector₀。