CN101710714B - Direct power control method for constant switching frequency of three-phase voltage type synchronization inverter - Google Patents

Abstract

The invention discloses a direct power control method for the constant switching frequency of a three-phase voltage type synchronization inverter, which comprises the following steps of: performing three-phase/two-phase stationary coordinate conversion by acquiring three-phase electric network voltage and three-phase alternating current; acquiring the electric network voltage and the alternating current in a two-phase stationary coordinate system, and calculating instantaneous active and reactive power feedbacks of the synchronization inverter and the active and reactive powers of a system according to the electric network voltage and the alternating current; providing a direct power controller based on a slip form variable structure to directly acquire the output voltage reference of the synchronization inverter in the two-phase stationary coordinate system; and generating a switching signal of a converter power device through space vector pulse duration modulation to control the running of the three-phase voltage type synchronization inverter. The direct power control method does not need synchronous speed rotation coordinate conversion and a design of a complex current inner loop controller, and has the advantages of quick power dynamic response, constant switching frequency and strong robustness.

Description

A kind of direct Power Control method of constant switching frequency of three-phase voltage type synchronization inverter

Technical field

The present invention relates to the control method of three-phase voltage type synchronization inverter, especially need not current inner loop controller, the constant combining inverter direct Power Control method of switching frequency.

Background technology

Growing along with regenerative resources such as wind energy, solar energy, fuel cells, three-phase voltage type synchronization inverter has obtained using widely because of instantaneous meritorious, the reactive power regulating power of its good output current characteristic and decoupling zero.At present, meritorious, the reactive power decoupling zero control of combining inverter adopt the vector control of or virtual electrical network flux linkage orientation directed based on line voltage to realize mostly.Vector control by with the leg speed rotating coordinate transformation with the three-phase alternating current stream translation, be decomposed into meritorious, reactive power current component in the synchronous rotating frame, pass through ratio-integration (PI) adjuster then and implement, thereby realize decoupling zero control instantaneous meritorious, the reactive power of inverter to independent control meritorious, the reactive power electric current.Yet this vector control scheme needs synchronously rotating reference frame conversion, inlet wire inductance value to be used to gain merit/the cross decoupling compensation of reactive current and comparatively complicated current PI controller parameter adjusting, so meritorious, the reactive power decoupling performance of combining inverter will depend on rotating coordinate transformation and the control system precision of inductance value and the design of PI parameter to a great extent.Meanwhile, come from the thought that exchanges alternating current machine direct torque control in the legacy system, direct Power Control also is suggested and is applied in the three-phase voltage type synchronization inverter system, the basic principle that this control method is implemented is: in a sampling period according to instantaneous meritorious, the error of reactive power and the position signalling of line voltage or virtual electrical network magnetic linkage, in the voltage vector switch list of setting in advance, directly choose suitable combining inverter output voltage vector, make instantaneous meritorious, the reactive power of combining inverter output follow the tracks of its set-point quickly and accurately.About the direct Power Control scheme of three-phase voltage type synchronization inverter, retrieving representative pertinent literature has:

I.T.Noguchi，H.Tomiki，S.Kondo，and?I.Takahashi，“Direct?Power?Control?ofPWM?Converter?Without?Power-Source?Voltage?Sensors，”IEEE?Trans.Ind.Electron.，vol.34，no.3，pp.473-479，May/Jun.1998.

II.M.Malinowski，M.P.Kazmierkowski，S.Hansen，F.Blaabjerg，and?G?D.Marques，“Virtual-Flux-Based?Direct?Power?Control?of?Three-Phase?PWMRectifiers，”IEEE?Trans.Ind.Appl.，vol.37，no.4，pp.1019-1027，Jul./Aug.2001.

The control method that above-mentioned document proposed (can be described as inquiry switch list direct Power Control, English and be called for short be respectively Look-up-table direct power control, LUT-DPC) available Fig. 1 illustrates, three-phase voltage type synchronization inverter 1 exchanges outlet side and links through inlet wire reactor 2 and three phase network, that the instantaneous decoupling zero control meritorious, reactive power of combining inverter is adopted is meritorious, reactive power hysteresis comparator 8 and directly inquire about switch list 9 and realize that its processing procedure is: utilize one group of three voltage sensor 3 to gather three phase network voltage signal U _Gabc, one group of three current Hall transducer 4 gather three-phase alternating current signal I _Gabc, the three phase network voltage signal U that collects _GabcWith three-phase alternating current signal I _GabcBy three-phase/two-phase static coordinate conversion module 5, be converted to the voltage vector U in the static α β of the two-phase coordinate system respectively _{G α β}With current vector I _{G α β}, the voltage vector U of acquisition _{G α β}With current vector I _{G α β}Calculate module 6 and calculate instantaneous meritorious, reactive power feedback P through instantaneous meritorious, reactive power _g, Q _g, with the Feedback of Power P that calculates _g, Q _gWith power given P _g ^*, Q _g ^*Obtain meritorious, the reactive power error symbol S that switch lists 9 use by instantaneous meritorious, reactive power hysteresis comparator 8 _P, S _Q, according to this error symbol S _P, S _QDirectly inquire about set switch list 9 with the line voltage vector sector signals N that obtains through 7 detections of line voltage sector detection module, thereby obtain the required switching signal S of three-phase grid-connected inverter power device _AbcWith the operation of control combining inverter, realizes the direct control and the tracking fast of instantaneous meritorious, reactive power.

By above-mentioned analytic process as seen, the inquiry switch list direct Power Control of combining inverter its essence is in a sampling period error and the line voltage position signalling according to instantaneous meritorious, reactive power, in pre-determined voltage vector switch list, directly choose suitable combining inverter output vector voltage, make that combining inverter is meritorious, its set-point is followed the tracks of in reactive power output fast, accurately.The advantage of this method is to need not synchronously rotating reference frame conversion and current inner loop design of Controller, and dynamic response is fast, realization is simple and need not system parameters, has higher robustness.Yet its remarkable defective is that the switching frequency of combining inverter is non-constant, and change along with the variation of meritorious, reactive power hysteresis comparator bandwidth and system conditions, be unfavorable for exchanging the design of output filter reactor, cause to the serious harmonic pollution of electrical network in parallel, even can cause system oscillation.

Therefore, need the direct Power Control method of exploring a kind of combining inverter constant switching frequency badly, make it possess Fast Dynamic response and good output current spectral characteristic.

Summary of the invention

The direct Power Control method that the purpose of this invention is to provide a kind of constant switching frequency of three-phase voltage type synchronization inverter.This method need not the design of synchronously rotating reference frame conversion and current inner loop, possesses Fast Dynamic response, good output current frequency spectrum and stronger system robustness.

The direct Power Control method of constant switching frequency of three-phase voltage type synchronization inverter of the present invention may further comprise the steps:

(i) utilize one group of three voltage sensor to gather three phase network voltage signal U _Gabc, one group of three current Hall sensor acquisition three-phase alternating current signal I _Gabc

(ii) with the three phase network voltage signal U that collects _GabcWith three-phase alternating current signal I _GabcPass through three-phase/two-phase static coordinate conversion module respectively, obtain the voltage vector U in the static α β of the two-phase coordinate system _{G α β}With current vector I _{G α β}

(iii) with voltage vector U in the static α β of the two-phase coordinate system that obtains _{G α β}With current vector I _{G α β}Through instantaneous meritorious, reactive power calculating module calculating, obtain instantaneous meritorious, reactive power feedback P _g, Q _g

(iv) with the instantaneous power feedback P that calculates _g, Q _gWith power given P _g ^*, Q _g ^*Directly obtain the required combining inverter output voltage reference signal V in the static α β of two-phase coordinate system of voltage vector pulse width modulation module through direct Power Control device based on sliding moding structure _{G α β} ^*

(v) with combining inverter output voltage reference signal V in the static α β of the two-phase of the obtaining coordinate system _{G α β} ^*, directly, obtain the power device switching signal S of control three-phase voltage type synchronization inverter through after the modulation of space vector pulse width modulation module _Abc

The said direct Power Control device of the present invention based on sliding moding structure, its feature comprises following specific design process:

(i) set switching function S=[S ₁S ₂] ^T

Wherein, ${\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">S</figure-callout>}}_1=e_P\left(t\right)+K_P\underset{0}{\overset{t}{\&Integral;}}{e}_P\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}-e_P\left(0\right),$ ${\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">S</figure-callout>}}_2=e_Q\left(t\right)+K_Q\underset{0}{\overset{t}{\&Integral;}}{e}_Q\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}-e_Q\left(0\right),$ $e_P\left(t\right)=P_g^{*}-P_g,$ $e_Q\left(t\right)=Q_g^{*}-Q_g$ Be instantaneous power error, K _P, K _QFor on the occasion of ride gain;

(ii) through switching function is differentiated and is put in order and can get:

$\frac{\mathrm{dS}}{\mathrm{dt}}=F+{\mathrm{DV}}_{\mathrm{g\&alpha;\&beta;}}^{*},$

Wherein, F=[F ₁F ₂] ^T, $V_{\mathrm{g\&alpha;\&beta;}}^{*}={\left[\begin{array}{cc}{v}_{\mathrm{g\&alpha;}}& v_{\mathrm{g\&beta;}}\end{array}\right]}^T,$

${\mathrm{<figure-callout\; id="1"\; label="F"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">F</figure-callout>}}_1=\frac{3}{{2L}_g}({u_{\mathrm{g\&alpha;}}}^2+{u_{\mathrm{g\&beta;}}}^2)+\frac{R_g}{L_g}{P}_g+{\mathrm{\&omega;}}_1{Q}_g+K_P(P_g^{*}-P_g),$ $F_2=\frac{R_g}{L_g}{Q}_g-{\mathrm{\&omega;}}_1{P}_g+K_Q(Q_g^{*}-Q_g)$ $D=-\frac{3}{{2L}_g}\left[\begin{array}{cc}{u}_{\mathrm{g\&alpha;}}& u_{\mathrm{g\&beta;}}\\ u_{\mathrm{g\&beta;}}& -u_{\mathrm{g\&alpha;}}\end{array}\right],$ L _gAnd R _gBe respectively the inductance value and the equivalent resistance of inlet wire reactor, ω ₁Be the line voltage angular frequency.

(iii) can design corresponding controller, combining inverter output voltage reference signal V in the static α β of the output two-phase coordinate system according to the derivative expression formula of switching function _{G α β} ^*For

$U_{\mathrm{r\&alpha;\&beta;}}^{s*}=-D^{-1}\{\left[\begin{array}{c}{F}_1\\ {\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">F</figure-callout>}}_2\end{array}\right]+\left[\begin{array}{cc}{K}_{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">P</figure-callout>}1}& 0\\ 0& {\mathrm{<figure-callout\; id="1"\; label="K\; Q"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">K</figure-callout>}}_Q\end{array}\right]\left[\begin{array}{c}\mathrm{sgn}\left(S_1\right)\\ \mathrm{sgn}\left(S_2\right)\end{array}\right]\},$

In the formula, switch function sgn (S ₁) and sgn (S ₂) available continuous function substitutes to reduce power jitter, its expression formula is

λ wherein _j＞0 is the width of sliding-mode surface, and j=1,2 represents instantaneous meritorious, reactive power respectively.

Control method of the present invention is the direct Power Control of constant switching frequency of three-phase voltage type synchronization inverter.The present invention need gather three phase network voltage signal and three-phase alternating current signal in the control, this signal only need pass through three-phase/two-phase static coordinate conversion and obtain line voltage in the static α β of the two-phase coordinate system, the alternating current vector, calculate instantaneous meritorious in view of the above, the feedback quantity of reactive power, this Feedback of Power and system power are given in the static α β of two-phase coordinate system directly obtains the combining inverter output reference voltage by the direct Power Control device based on sliding moding structure, this reference voltage is as the space vector pulse width modulation reference signal, generate the pwm switch signal of power device of inverter through ovennodulation, obtain constant switching frequency, accurately, control the instantaneous meritorious of combining inverter apace, reactive power output.

Control method of the present invention is simple.Than traditional inquiry switch list direct Power Control method, need not to increase extra hardware detection or controlling unit, what only line voltage that need obtain according to sampling and alternating current calculate is instantaneous meritorious, reactive power directly obtains the reference of combining inverter output voltage by the direct Power Control device based on sliding moding structure as feedback and given power, obtain the switching signal of power device through space vector pulse width modulation, guaranteed the constant switching frequency operation of combining inverter, meanwhile, The whole control algorithm implementation process need not to carry out synchronously rotating reference frame conversion and complicated current inner loop design of Controller, has guaranteed control system Fast Dynamic characteristic.

The inventive method is except that being applicable to the three-phase voltage type synchronization inverter system, can also be applicable to effective control of the single-phase or heterogeneous parallel network reverse device of all kinds of PWM control forms that other adopt HF switch self-turn-off device formation, parallel network reverse device as solar energy, fuel cell generation, the electronic power inversion device of flexible transmission system, and the effective control of convertor assembly of the motor/generator in the speed governing Electric Drive.

Description of drawings

Fig. 1 is the tradition inquiry switch list direct Power Control theory diagram of three-phase voltage source type interconnected inverter.

Fig. 2 is the direct Power Control theory diagram of the constant switching frequency of three-phase voltage type synchronization inverter that proposes of the present invention.

Instantaneous meritorious, reactive power step response when Fig. 3 inquires about the switch list direct Power Control for adopting tradition; Wherein, (A) figure is an active power step response, and (B) figure is a reactive power step response; (A) figure and (B) (a) among the figure be instantaneous active power (W); (b) be instantaneous reactive power (Var); (c) be three-phase alternating current (A).

Fig. 4 instantaneous meritorious, reactive power step response during for the direct Power Control that adopts the present invention and propose; Wherein, (A) figure is an active power step response, and (B) figure is a reactive power step response; (A) figure and (B) (a) among the figure be instantaneous active power (W); (b) be instantaneous reactive power (Var); (c) be three-phase alternating current (A).

Alternating current spectrogram when Fig. 5 exports 2kW, reactive power output 1kVar for instantaneous active power.(A) figure adopts tradition inquiry switch list direct Power Control; (B) figure adopts the constant switching frequency direct Power Control that the present invention proposes.

Fig. 6 is for the direct Power Control that adopts the present invention and propose instantaneously under with different inlet wire reactor inductance value error conditions is gained merit in control system, reactive power step response; Wherein, (A) figure is negative 25% inductance value error, and (B) figure is a zero inductance value error, and (C) figure is positive 25% inductance value error; (a) instantaneous active power (W); (b) instantaneous reactive power (Var); (c) three-phase alternating current (A).

Embodiment

The present invention is further described below in conjunction with accompanying drawing and embodiment.

Fig. 2 is the schematic diagram that adopts the direct Power Control method of a kind of constant switching frequency of three-phase voltage type synchronization inverter that the present invention proposes, comprise controlling object three-phase voltage type synchronization inverter 1, exchange the inlet wire reactor 2 that outlet side links with combining inverter, be used for the current Hall transducer 4 that the voltage sensor 3 of three phase network voltage detecting and three-phase alternating current detect, and realize instantaneous meritorious, the control loop that reactive power is regulated of combining inverter.Control loop is made of feedback signal treatment channel and forward direction control channel, wherein the feedback signal treatment channel comprises the three-phase/two-phase static coordinate conversion module 5 that is used for obtaining the static α β of two-phase coordinate system signal, is used to calculate instantaneous instantaneous meritorious, reactive power meritorious, the reactive power feedback and calculates module 6; Forward direction control channel comprises based on the direct Power Control device 10 of sliding moding structure and is used for according to the combining inverter output voltage with reference to the space vector pulse width modulation module 11 that produces pulse-width signal.

With a 2kVA three-phase voltage type synchronization inverter prototyping system is example, and with reference to Fig. 2, the method that adopts the present invention to propose is controlled its operation, and concrete implementation step is as follows:

(i) utilize one group three voltage sensors (3) to gather three phase network voltage signal U _Gabc, one group of three current Hall transducer (4) gather three-phase alternating current signal I _Gabc

(ii) with the three phase network voltage signal U that collects _GabcWith three-phase alternating current signal I _GabcPass through three-phase/two-phase static coordinate conversion module (5) respectively, obtain the voltage vector U in the static α β of the two-phase coordinate system _{G α β}With current vector I _{G α β}With the line voltage is example, and based on permanent phase amplitude principle, its three-phase/two-phase static coordinate conversion is as shown in the formula expression

$\left[\begin{array}{c}{u}_{\mathrm{g\&alpha;}}\\ u_{\mathrm{g\&beta;}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& \frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{ga}}\\ u_{\mathrm{gb}}\\ u_{\mathrm{gc}}\end{array}\right];$

(iii) with voltage vector U in the static α β of the two-phase coordinate system that obtains _{G α β}With current vector I _{G α β}Through instantaneous meritorious, reactive power calculating module (6) calculating, obtain instantaneous meritorious, reactive power feedback P _g, Q _g

The instantaneous output of combining inverter is meritorious, reactive power expression formula is

$P_g=-\frac{3}{2}(u_{\mathrm{s\&alpha;}}{i}_{\mathrm{s\&alpha;}}+u_{\mathrm{s\&beta;}}{i}_{\mathrm{s\&beta;}});$

$Q_g=-\frac{3}{2}(u_{\mathrm{g\&beta;}}{i}_{\mathrm{g\&alpha;}}-u_{\mathrm{g\&alpha;}}{i}_{\mathrm{g\&beta;}})$

(iv) with the instantaneous power feedback P that calculates _g, Q _gWith power given P _g ^*, Q _g ^*Directly obtain required combining inverter (1) the output voltage reference signal V in the static α β of two-phase coordinate system of space vector pulse width modulation module (11) through direct Power Control device (10) based on sliding moding structure _{G α β} ^*

(v) with combining inverter output voltage reference signal V in the static α β of the two-phase of the obtaining coordinate system _{G α β} ^*, directly pass through space vector pulse width modulation module (11) modulation after, obtain the power device switching signal S of control three-phase voltage type synchronization inverter (1) _Abc

Above-mentioned steps (iv) in said direct Power Control device (10) based on sliding moding structure, comprise that a combining inverter is instantaneous meritorious, the sliding mode controller of reactive power, this controller is set the instantaneous meritorious of combining inverter, the reactive power error is switching function S, by to the continuous switching controls output variable of the differentiation of switching function symbol, change the control system structure so that system state variables, be instantaneous meritorious, reactive power moves on the space diverter surface S=0 of prior setting, control system realizes the direct control of instantaneous power along the operation of diverter surface sliding formwork then.Its design procedure is as described below:

At first, set switching function S=[S ₁S ₂] ^T

Wherein,

$\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">S</figure-callout>}}_1=e_P\left(t\right)+K_P\underset{0}{\overset{t}{\text{\&Integral;}}}{e}_P\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}-e_P\left(0\right)\\ {\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">S</figure-callout>}}_2=e_Q\left(t\right)+K_Q\underset{0}{\overset{t}{\&Integral;}}{e}_Q\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}-e_Q\left(0\right)\end{array},\begin{array}{c}{e}_P\left(t\right)=P_s^{*}-P_s\\ e_Q\left(t\right)=Q_s^{*}-Q_s\end{array}$ Be instantaneous power error, K _P, K _QFor on the occasion of ride gain;

Secondly, through switching function is differentiated and is put in order and can get:

$\frac{\mathrm{dS}}{\mathrm{dt}}=F+{\mathrm{DV}}_{\mathrm{r\&alpha;\&beta;}}^{s*},$

Wherein,

F＝[F ₁?F ₂] ^T， $V_{\mathrm{r\&alpha;\&beta;}}^{*}={\left[\begin{array}{cc}{v}_{\mathrm{g\&alpha;}}& v_{\mathrm{g\&beta;}}\end{array}\right]}^T,$

$F_1=\frac{3}{{2L}_g}({u_{\mathrm{g\&alpha;}}}^2+{u_{\mathrm{g\&beta;}}}^2)+\frac{R_g}{L_g}{P}_g+{\mathrm{\&omega;}}_1{Q}_g+K_P(P_g^{*}-P_g),$

${\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">F</figure-callout>}}_2=\frac{R_g}{L_g}{Q}_g-{\mathrm{\&omega;}}_1{P}_g+K_Q({Q_g}^{*}-Q_g)$

$D=-\frac{3}{{2L}_g}\left[\begin{array}{cc}{u}_{\mathrm{g\&alpha;}}& u_{\mathrm{g\&beta;}}\\ u_{\mathrm{g\&beta;}}& -u_{\mathrm{g\&alpha;}}\end{array}\right],$ L _gAnd R _gBe respectively the inductance value and the equivalent resistance of inlet wire reactor, ω ₁Be the line voltage angular frequency.

At last, can design corresponding controller, combining inverter output voltage reference signal V in the static α β of the output two-phase coordinate system according to the derivative expression formula of switching function _{G α β} ^*For

$V_{\mathrm{g\&alpha;\&beta;}}^{*}=-D^{-1}\left\{\left[\begin{array}{c}{F}_1\\ F_2\end{array}\right]\left[\begin{array}{cc}{\mathrm{<figure-callout\; id="1"\; label="K\; P"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">K</figure-callout>}}_P& 0\\ 0& {\mathrm{<figure-callout\; id="1"\; label="K\; Q"\; filenames="H2009101558917E00011.png,H2009101558917E00012.png"\; state="\{\{state\}\}">K</figure-callout>}}_Q\end{array}\right]\left[\begin{array}{c}\mathrm{sgn}\left(S_1\right)\\ \mathrm{sgn}\left(S_2\right)\end{array}\right]\right\},$

In the formula, switch function sgn (S ₁) and sgn (S ₂) available continuous function substitutes to reduce power jitter, its expression formula is

λ wherein _j＞0 is the width of sliding-mode surface, and j=1,2 represents instantaneous meritorious, reactive power respectively.

Comparison diagram 2 and Fig. 1 as can be seen, control method of the present invention is simple.Than traditional inquiry switch list direct Power Control method, need not to increase extra hardware detection or controlling unit, what only line voltage that need obtain according to sampling and alternating current calculate is instantaneous meritorious, reactive power is directly passed through direct Power Control device based on sliding moding structure as feedback and power given, thereby obtain the reference of combining inverter output voltage, obtain the switching signal of power device through space vector pulse width modulation, realized the constant switching frequency operation of combining inverter, meanwhile, the implementation process of The whole control algorithm need not to carry out synchronously rotating reference frame conversion and complicated current inner loop design of Controller, has guaranteed and the suitable dynamic response rapidity of tradition inquiry switch list direct Power Control.

Fig. 3 and Fig. 4 are respectively and adopt direct control method that tradition inquiry switch list direct Power Control and the present invention propose at instantaneous meritorious, response comparative result when the reactive power step changes.In the control algolithm implementation process, the sample frequency of tradition inquiry switch list direct Power Control is got 40kHz, and the direct Power Control that the present invention proposes, its sample frequency and switching frequency are got 10kHz and 2.5kHz respectively.

As shown in Figure 3 and Figure 4, instantaneous active power is when 0.03s and the variation of 0.07s generation step, and instantaneous reactive power remains unchanged; Equally, instantaneous reactive power is when 0.03s and the variation of 0.07s generation step, and instantaneous active power also remains unchanged, thereby shows that two kinds of direct Power Control methods have all realized independent regulation and decoupling zero control meritorious, reactive power.In addition, be not difficult to find that from instantaneous step response meritorious, reactive power direct Power Control method proposed by the invention has kept inquiring about with tradition the suitable dynamic response rapidity of direct Power Control scheme of switch list.Yet, comparison diagram 3 and Fig. 4 result are not difficult to find, the direct Power Control scheme of tradition inquiry switch list has produced bigger power fluctuation and serious current harmonics distortion, and the direct Power Control scheme that the present invention proposes, and it is meritorious, reactive power and alternating current steady-state response are comparatively level and smooth.In order to compare the response current frequency spectrum of two kinds of direct Power Control schemes better, Fig. 5 has provided respectively at instantaneous active power output 2kW, the alternating current spectrogram and the THD value of two kinds of direct Power Control during instantaneous reactive power output 1kVar, easily see, the harmonic spectrum that the direct Power Control method of tradition inquiry switch list has produced bigger low-order harmonic and broad distributes, and the control method that the present invention proposes, THD is lower for its electric current, and only at switching frequency point (2.5kHz) and integer multiple frequency point (5kHz thereof, 7.5kHz, 10kHz ...) there is harmonic components, promptly embody constant switching frequency.

In order to further specify the robustness that the present invention proposes the constant switching frequency direct Power Control, Fig. 6 has provided the dynamic and static response of combining inverter system when adopting different inlet wire reactor inductance value in the control system.Wherein, Fig. 6 (a)～6 (c) be respectively in the control system inductance value error for negative 25%, 0 and positive 25% o'clock result, running status such as variable power are identical with operating condition shown in Figure 4.Be not difficult to find by Fig. 6 result, even under the situation of big system parameter variations, the constant switching frequency direct Power Control that adopts this paper to propose still can keep good dynamic and static characteristic, thereby has verified that the direct Power Control method that the present invention proposes has stronger robustness.

Claims (1)

1. the direct Power Control method of a constant switching frequency of three-phase voltage type synchronization inverter is characterized in that may further comprise the steps:

(i) utilize one group three voltage sensors (3) to gather three phase network voltage signal U _Gabc, one group of three current Hall transducer (4) gather three-phase alternating current signal I _Gabc

(ii) with the three phase network voltage signal U that collects _GabcWith three-phase alternating current signal I _GabcPass through three-phase/two-phase static coordinate conversion module (5) respectively, obtain the voltage vector U in the static α β of the two-phase coordinate system _{G α β}With current vector I _{G α β}

(iii) with voltage vector U in the static α β of the two-phase coordinate system that obtains _{G α β}With current vector I _{G α β}Through instantaneous meritorious, reactive power calculating module (6) calculating, obtain instantaneous meritorious, reactive power feedback P _g, Q _g

(iv) with the instantaneous power feedback P that calculates _g, Q _gAnd power given

Direct Power Control device (10) adjusting, computing through based on sliding moding structure directly obtain required combining inverter (1) the output voltage reference signal in the static α β of two-phase coordinate system of space vector pulse width modulation module (11)

(v) with combining inverter output voltage reference signal in the static α β of the two-phase of the obtaining coordinate system

Directly, obtain the power device switching signal S of control three-phase voltage type synchronization inverter (1) through after space vector pulse width modulation module (11) modulation _Abc

Above-mentioned direct Power Control device (10) is regulated, computing, and step is as follows:

(i) set switching function S=[S ₁S ₂] ^T

Wherein, $S_1=e_P\left(t\right)+K_P\underset{0}{\overset{t}{\&Integral;}}{e}_P\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}-e_P\left(0\right),$ $S_2=e_Q\left(t\right)+K_Q\underset{0}{\overset{t}{\&Integral;}}{e}_Q\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}-e_Q\left(0\right),$ $e_P\left(t\right)=P_g^{*}-P_g,$ $e_Q\left(t\right)=Q_g^{*}-Q_g,$ E wherein _P(t), e _Q(t) be the instantaneous power error, K _P, K _QFor on the occasion of ride gain;

(ii) through switching function is differentiated and is put in order and can get:

$\frac{\mathrm{dS}}{\mathrm{dt}}=F+{\mathrm{DV}}_{\mathrm{g\&alpha;\&beta;}}^{*},$

Wherein, $F={\left[\begin{array}{cc}{F}_1& F_2\end{array}\right]}^T,V_{\mathrm{g\&alpha;\&beta;}}^{*}={\left[\begin{array}{cc}{v}_{\mathrm{g\&alpha;}}& v_{\mathrm{g\&beta;}}\end{array}\right]}^T,$

$F_1=\frac{3}{2L_g}({u_{\mathrm{g\&alpha;}}}^2+{u_{\mathrm{g\&beta;}}}^2)+\frac{R_g}{L_g}{P}_g+{\mathrm{\&omega;}}_1{Q}_g+K_P(P_g^{*}-P_g),$ $F_2=\frac{R_g}{L_g}{Q}_g-{\mathrm{\&omega;}}_1{P}_g+K_Q(Q_g^{*}-Q_g)$ $D=-\frac{3}{2L_g}\left[\begin{array}{cc}{u}_{\mathrm{g\&alpha;}}& u_{\mathrm{g\&beta;}}\\ u_{\mathrm{g\&beta;}}& -u_{\mathrm{g\&alpha;}}\end{array}\right],$ L _gAnd R _gBe respectively the inductance value and the equivalent resistance of inlet wire reactor, ω ₁Be the line voltage angular frequency;

(iii) design corresponding controller, combining inverter output voltage reference signal in the static α β of the output two-phase coordinate system according to the derivative expression formula of switching function

For

$V_{\mathrm{g\&alpha;\&beta;}}^{*}=-D^{-1}\{\left[\begin{array}{c}{F}_1\\ F_2\end{array}\right]+\left[\begin{array}{cc}{K}_{P1}& 0\\ 0& K_{Q1}\end{array}\right]\left[\begin{array}{c}\mathrm{sgn}\left(S_1\right)\\ \mathrm{sgn}\left(S_2\right)\end{array}\right]\},$

In the formula, switch function sgn (S ₁) and sgn (S ₂) substitute to reduce power jitter with continuous function, its expression formula is

λ wherein _j＞0 is the width of sliding-mode surface, and j=1,2 represents instantaneous meritorious, reactive power respectively.

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