CN101771361A - Method for controlling direct power of grid-connected inverter without non-AC voltage sensor - Google Patents

Abstract

The invention provides a method for controlling direct power of a grid-connected inverter without any non-AC voltage sensor and belongs to the field of electric energy transformation. The invention aims to solve the problem that because an initial value of an integrator in a virtual flux observer of a voltage vector on the network side is improperly selected, the grid-connected inverter cannot normally operate. The method comprises the following steps of: by transformation, obtaining components i alpha and i beta of the three-phase current value in a two-phase stationary coordinate system; by calculation, obtaining components us alpha and us beta of the inversion voltage value of the current grid-connected inverter in the two-phase stationary coordinate system; after the integration of the integrator, calculating components psi alpha and psi beta of the magnetic flux linkage of the voltage on the network side in the two-phase stationary coordinate system; calculating the instantaneous output active power p and reactive power q of the grid-connected inverter, and obtaining components usp * and usq * of the control voltage set value of the new grid-connected inverter in a two-phase rotary coordinate system; and finally obtaining the control signal of all power devices of the grid-connected inverter. The method can be used for direct power control of the grid-connected inverter.

Description

The direct Power Control method of grid-connected inverter without non-AC voltage sensor

Technical field

The present invention relates to a kind of direct Power Control method of grid-connected inverter without non-AC voltage sensor, belong to the transformation of electrical energy field.

Background technology

Combining inverter is as the key components of renewable energy system, and its control performance directly influences and network electric energy quality and grid connection efficiency.In the existing parallel network reverse control strategy, adopt Direct Current Control or voltage oriented vector control etc. mostly.There is the problem of anti-grid disturbance ability in Direct Current Control, and voltage oriented vector control then needs a large amount of control algolithms such as rotating coordinate transformation, realizes system complex, and performance of processors is had higher requirements.Especially, adopt the inverter of voltage oriented vector control all to adopt AC voltage sensor to detect the locking phase parallactic angle of voltage at present, though this can make system with higher power factor operation, but system bulk is increased, in case and AC voltage sensor lost efficacy, and then caused the whole system inverter failure.Direct Power Control (DPC) strategy with system's power output as controlled volume, need not electric current loop, simultaneously because the natural decoupling zero character of meritorious and reactive power has been avoided complicated algorithms such as coordinate transform, its control device is more direct, and the system that makes has higher reliability.And calculate instantaneous power by the notion of introducing virtual magnetic linkage based on direct Power Control (VF-DPC) method of virtual magnetic linkage, when saving AC voltage sensor, need not to calculate the differential of inverter current, the introducing of having avoided external high frequency to disturb; The introducing of integral element also has the advantage that suppresses voltage, current harmonics interference in the while method.But the indefinite integral link of using in the traditional virtual flux observation method, when starting, need know the initial value of virtual magnetic linkage, this value makes observed result produce dc shift if choose improper meeting, and the choosing of virtual magnetic linkage initial value can not depend on line voltage and directly obtain, and therefore can not directly apply to engineering reality.At present adopted inertial element to replace pure integration to the improvement of traditional virtual flux observation method, it need not to know the initial value of virtual magnetic linkage, but its final observed result is an approximation, when being used for direct Power Control, can produce the instantaneous power calculation deviation, this can make dynamic performance degenerate, and inversion efficiency descends, serious meeting produces voltage, current phase significantly to depart from, and causes the system can't operate as normal.

Summary of the invention

The direct Power Control method that the purpose of this invention is to provide a kind of grid-connected inverter without non-AC voltage sensor, it solved existing method since the integrator initial value in the virtual flux observer of voltage on line side vector choose improper, and the problem that the combining inverter that causes can't operate as normal.

Control method of the present invention is:

One, the output that filter is connected in combining inverter carries out filtering to output current, the three-phase electricity flow valuve of combining inverter output is carried out three-phase-two-phase coordinate transform, obtain the component i of three-phase electricity flow valuve under the two-phase rest frame of combining inverter output _αAnd i _βAt the input parallel connection direct electric capacity of combining inverter, with the component u of control voltage given value under the two-phase rest frame of combining inverter _{S α} ^*And u _{S β} ^*Respectively with the voltage U at dc capacitor two ends _DcMultiply each other, obtain the component u of inverter voltage value under the two-phase rest frame of current combining inverter _{S α}And u _{S β}

Two, with the component u of inverter voltage value under the two-phase rest frame of the current combining inverter that obtains in one _{S α}And u _{S β}Carry out integral processing by an integrator that has integration amplitude limit feedback element respectively, obtaining integral result respectively is ψ _{U α}And ψ _{U β}, pass through formula $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{\α}}={\mathrm{\ψ}}_{\mathrm{u\α}}+{\mathrm{Li}}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{\β}}={\mathrm{\ψ}}_{\mathrm{u\β}}+{\mathrm{Li}}_{\mathrm{\β}}\end{array}\right.$ Calculate the component ψ of virtual magnetic linkage under the two-phase rest frame of voltage on line side _αAnd ψ _β, L is the inductance value of filter in the formula;

Three, by the instantaneous power computing formula $\left\{\begin{array}{c}p=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\α}})\\ q=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\α}}+{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\β}})\end{array}\right.,$ ω is net top-cross stream voltage angle frequency in the formula, obtain the active power p and the reactive power q of the instantaneous output of combining inverter, described active power p is compared with the active power set-point of combining inverter, obtain comparative result, described reactive power q is compared with the reactive power set-point of combining inverter, obtain comparative result, above-mentioned two comparative results are regulated the back by a closed-loop regulator respectively obtain two magnitudes of voltage, described two magnitudes of voltage are controlled the component u of voltage given value under the two-phase rotating coordinate system as new combining inverter _Sp ^*And u _Sq ^*

Four, by formula ${\mathrm{\θ}}_{\mathrm{\ψ}}=\arctan \frac{{\mathrm{\ψ}}_{\mathrm{\β}}}{{\mathrm{\ψ}}_{\mathrm{\α}}},$ The component ψ of virtual magnetic linkage under the two-phase rest frame according to voltage on line side _αAnd ψ _βCalculate the vectorial angle θ of virtual flux linkage vector _ψ, again with described vectorial angle θ _ψWith three in the component u of combining inverter control voltage given value under the two-phase rotating coordinate system that obtain _Sp ^*And u _Sq ^*Through the conversion of rotation-static coordinate, obtain the component u of control voltage given value under the two-phase rest frame of new combining inverter _{S α} ^*And u _{S β} ^*, with new u _{S α} ^*And u _{S β} ^*Calculate through the space vector of voltage control algolithm, obtain the control signal of each power device of combining inverter, realize direct Power Control combining inverter.

Advantage of the present invention is:

The invention solves exist in the conventional method choose the improper problem that system can't operate as normal that causes because of initial value in the integrator.It need not detection of grid voltage, has reduced cost, has improved reliability; The no current control ring need not to calculate the differential value of electric current, and algorithm is simple relatively, and antijamming capability is strong; The power estimating method that is adopted does not rely on the integrator initial value, significantly improves control performance; Simultaneously the instantaneous active power of output and the reactive power of combining inverter are directly controlled, dynamic response is fast.

Description of drawings

Fig. 1 is that the signal of control method of the present invention moves towards schematic diagram; Fig. 2 is the equivalent circuit diagram of three-phase six switch combining inverters; Fig. 3 is the schematic diagram that has the integrator of integration amplitude limit feedback element; Fig. 4 is that the control method signal of execution mode two moves towards schematic diagram.

Embodiment

Embodiment one: below in conjunction with Fig. 1 to Fig. 3 present embodiment is described, the control method of present embodiment is:

One, the output that filter is connected in combining inverter carries out filtering to output current, the three-phase electricity flow valuve of combining inverter output is carried out three-phase-two-phase coordinate transform, obtain the component i of three-phase electricity flow valuve under the two-phase rest frame of combining inverter output _αAnd i _βAt the input parallel connection direct electric capacity of combining inverter, with the component u of control voltage given value under the two-phase rest frame of combining inverter _{S α} ^*And u _{S β} ^*Respectively with the voltage U at dc capacitor two ends _DcMultiply each other, obtain the component u of inverter voltage value under the two-phase rest frame of current combining inverter _{S α}And u _{S β}

Two, with the component u of inverter voltage value under the two-phase rest frame of the current combining inverter that obtains in one _{S α}And u _{S β}Carry out integral processing by an integrator that has integration amplitude limit feedback element respectively, obtaining integral result respectively is ψ _{U α}And ψ _{U β}, pass through formula $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{\α}}={\mathrm{\ψ}}_{\mathrm{u\α}}+{\mathrm{Li}}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{\β}}={\mathrm{\ψ}}_{\mathrm{u\β}}+{\mathrm{Li}}_{\mathrm{\β}}\end{array}\right.$ Calculate the component ψ of virtual magnetic linkage under the two-phase rest frame of voltage on line side _αAnd ψ _β, L is the inductance value of filter in the formula;

Three, by the instantaneous power computing formula $\left\{\begin{array}{c}p=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\α}})\\ q=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\α}}+{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\β}})\end{array}\right.,$ ω is net top-cross stream voltage angle frequency in the formula, obtain the active power p and the reactive power q of the instantaneous output of combining inverter, described active power p is compared with the active power set-point of combining inverter, obtain comparative result, described reactive power q is compared with the reactive power set-point of combining inverter, obtain comparative result, above-mentioned two comparative results are regulated the back by a closed-loop regulator respectively obtain two magnitudes of voltage, described two magnitudes of voltage are controlled the component u of voltage given value under the two-phase rotating coordinate system as new combining inverter _Sp ^*And u _Sq ^*

Four, by formula ${\mathrm{\θ}}_{\mathrm{\ψ}}=\arctan \frac{{\mathrm{\ψ}}_{\mathrm{\β}}}{{\mathrm{\ψ}}_{\mathrm{\α}}},$ The component ψ of virtual magnetic linkage under the two-phase rest frame according to voltage on line side _αAnd ψ _βCalculate the vectorial angle θ of virtual flux linkage vector _ψ, again with described vectorial angle θ _ψWith three in the component u of combining inverter control voltage given value under the two-phase rotating coordinate system that obtain _Sp ^*And u _Sq ^*Through the conversion of rotation-static coordinate, obtain the component u of control voltage given value under the two-phase rest frame of new combining inverter _{S α} ^*And u _{S β} ^*, with new u _{S α} ^*And u _{S β} ^*Calculate through the space vector of voltage control algolithm, obtain the control signal of each power device of combining inverter, realize direct Power Control combining inverter.

The biphase current value i of described combining inverter input _a, i _bObtain by current sensor senses, the third phase current value is according to the three-phase current addition and be zero to obtain.

The component u of the inverter voltage value of the current combining inverter described in two under the two-phase rest frame _{S α}And u _{S β}Carry out integral processing by an integrator that has integration amplitude limit feedback element respectively, obtaining integral result respectively is ψ _{S α}And ψ _{S β}, be to pass through formula $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{u\α}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\α}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{Z}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{u\β}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\β}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{Z}_{\mathrm{\β}}\end{array}\right.$ Calculate, s is the multiple parameter in the complex frequency domain in the formula, Z _α, Z _βBe ψ _{U α}And ψ _{U β}Through the output valve after the amplitude limit link, Z _α, Z _βInitial value be zero.

Operation principle:

Shown in Figure 2, be the main circuit diagram of three-phase six switch grid-connected inverter without non-AC voltage sensor, comprise filter, half-bridge inverter and dc capacitor.In order to cancel AC voltage sensor, introduce the notion of virtual magnetic linkage, be used to calculate instantaneous active power and reactive power.With inverter left part equivalence among Fig. 2 is an alternating current motor, and voltage on line side 1 equivalence is to be produced by virtual magnetic linkage.Under the two-phase rest frame, the defining virtual flux linkage vector

For: $\stackrel{\→}{\mathrm{\ψ}}=\∫\stackrel{\→}{u}\mathrm{dt}$ (formula one) is in the formula Be the voltage on line side vector, $\stackrel{\→}{u}=\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]$ (formula two), u _αAnd u _βBe the component of voltage of voltage on line side vector under the two-phase rest frame, then have: $\stackrel{\→}{\mathrm{\ψ}}=\left[\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{c}{\∫u}_{\mathrm{\α}}\mathrm{dt}\\ {\∫u}_{\mathrm{\β}}\mathrm{dt}\end{array}\right]$ (formula three).

Definition net side input current vector

For: $\stackrel{\→}{i}=\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\sqrt{2/3}\left[\begin{array}{cc}3/2& 0\\ \sqrt{3}/2& \sqrt{3}\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\end{array}\right]$ (formula four), i in the formula _a, i _bBe net side inversion phase current.The output voltage vector of combining inverter

For: ${\stackrel{\→}{u}}_s=\left[\begin{array}{c}{u}_{\mathrm{s\α}}\\ u_{\mathrm{s\β}}\end{array}\right]=U_{\mathrm{dc}}\left[\begin{array}{c}{u}_{\mathrm{s\α}}^{*}\\ u_{\mathrm{s\β}}^{*}\end{array}\right]$ (formula five), u _{S α}And u _{S β}Be respectively the component of combining inverter output voltage under the two-phase rest frame.

Under the two-phase rest frame, the Mathematical Modeling of the component of voltage of voltage on line side vector under the two-phase rest frame of three-phase grid-connected inverter is: $\left\{\begin{array}{c}{u}_{\mathrm{\α}}=L\frac{{\mathrm{di}}_{\mathrm{\α}}}{\mathrm{dt}}+u_{\mathrm{s\α}}\\ u_{\mathrm{\β}}=L\frac{{\mathrm{di}}_{\mathrm{\β}}}{\mathrm{dt}}+u_{\mathrm{s\β}}\end{array}\right.$ (formula six) with formula six substitution formula three, obtains: $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{\α}}={\mathrm{Li}}_{\mathrm{\α}}+{\∫u}_{\mathrm{s\α}}\mathrm{dt}\\ {\mathrm{\ψ}}_{\mathrm{\β}}={\mathrm{Li}}_{\mathrm{\β}}+{\∫u}_{\mathrm{s\β}}\mathrm{dt}\end{array}\right.$ (formula seven), then the voltage on line side vector is:

$\stackrel{\→}{u}=\frac{\mathrm{d\ψ}}{\mathrm{dt}}{|}_{\mathrm{\α}}+\frac{\mathrm{d\ψ}}{\mathrm{dt}}{|}_{\mathrm{\β}}+\mathrm{j\ω}({\mathrm{\ψ}}_{\mathrm{\α}}+j{\mathrm{\ψ}}_{\mathrm{\β}})$ (formula eight), ψ is the virtual magnetic linkage amplitude of voltage on line side in the formula.

Instantaneous expression formula meritorious and reactive power is: $\left\{\begin{array}{c}p=\mathrm{Re}(\stackrel{\→}{u}\⊗{\stackrel{\→}{i}}^{*})\\ q=\mathrm{Im}(\stackrel{\→}{u}\⊗{\stackrel{\→}{i}}^{*})\end{array}\right.$ (formula nine) is in the formula

For the conjugation of inverter current, for three-phase balanced system, d ψ/dt=0 therefore with formula two and formula eight substitution formula nine, obtains: $\left\{\begin{array}{c}p=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\α}})\\ q=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\α}}+{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\β}})\end{array}\right.$ (formula ten), by formula seven and formula ten as can be known, can calculate instantaneous power by detecting instantaneous interchange parallel network reverse electric current and combining inverter output voltage, need not to detect net top-cross stream voltage, and avoided calculating the differential of electric current, this algorithm need not the synchronously rotating reference frame conversion simultaneously, has simplified algorithm.

The virtual flux observation that has integration amplitude limit feedback element:

As the above analysis, the accurate key of calculating of instantaneous power is the observation of virtual magnetic linkage.Formula seven is bases of virtual flux observation, owing to contain integral in the formula, if initial value for integral is chosen the improper direct current offset that can occur in various degree, the magnetic linkage circle track center of circle that observation is come out will be in the origin of coordinates; In addition, contain DC quantity, can cause integrated value drift phenomenon to occur, be easy to cause integration saturated, and then produce the instantaneous power calculation deviation if be integrated item.For avoiding the problems referred to above, the inventive method proposes a kind of improved virtual flux observer (IVF), promptly adopts the integrator that has integration amplitude limit feedback element, as shown in Figure 3, replaces pure integral element.U wherein _{S α}, u _{S β}Calculate acquisition by formula five, the amplitude limit value of amplitude limit link must rationally be provided with among Fig. 3, is set to the amplitude ψ of virtual magnetic linkage here _Max, this value can be calculated by known voltage on line side amplitude and obtain.Under the two-phase rest frame, integrator is output as:

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{u\α}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\α}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{Z}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{u\β}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\β}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{Z}_{\mathrm{\β}}\end{array}\right.,$ Z in the formula _α, Z _βBe ψ _{U α}, ψ _{U β}Through the output valve after the amplitude limit link;

When integration is exported less than amplitude limit value, promptly $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{u\α}}\≤{\mathrm{\ψ}}_{\max }\\ {\mathrm{\ψ}}_{\mathrm{u\β}}\≤{\mathrm{\ψ}}_{\max }\end{array}\right.,$ Then have $\left\{\begin{array}{c}{Z}_{\mathrm{\α}}={\mathrm{\ψ}}_{\mathrm{u\α}}\\ Z_{\mathrm{\β}}={\mathrm{\ψ}}_{\mathrm{u\β}}\end{array}\right.,$ At this moment, $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{u\α}}=\frac{u_{\mathrm{s\α}}}{s}\\ {\mathrm{\ψ}}_{\mathrm{u\β}}=\frac{u_{\mathrm{s\β}}}{s}\end{array}\right.,$ Coming to the same thing of following formula and pure integral element; When integration is exported greater than amplitude limit value, then have $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{u\α}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\α}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{\mathrm{\ψ}}_{\max }\\ {\mathrm{\ψ}}_{\mathrm{u\β}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\β}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{\mathrm{\ψ}}_{\max }\end{array}\right.,$ Virtual flux observation result is: $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{\α}}={\mathrm{\ψ}}_{\mathrm{u\α}}+{\mathrm{Li}}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{\β}}={\mathrm{\ψ}}_{\mathrm{u\β}}+{\mathrm{Li}}_{\mathrm{\β}}\end{array}\right..$

The estimation of instantaneous power and control:

Based on instantaneous meritorious, the reactive power of improving virtual flux observer by formula $\left\{\begin{array}{c}p=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\α}})\\ q=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\α}}+{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\β}})\end{array}\right.$ Estimation obtains.Instantaneous active power and reactive power to combining inverter are carried out closed-loop control respectively, and the active power set-point is artificially given according to the capacity of combining inverter, move with unity power factor for making combining inverter, and reactive power is given as zero.The adjuster of active power and Reactive Power Control ring all adopts ratio-integral PI adjuster.

The generation of inverter output voltage control signal:

The output u of instantaneous meritorious and Reactive Power Control ring adjuster _Sp ^*And u _Sq ^*Be the component of combining inverter control voltage given amount under rotating coordinate system, it is rotated-coordinate transform of rest frame, obtains new inverter and control the component u of voltage given value under the two-phase rest frame _{S α} ^*And u _{S β} ^*, transformation for mula is

$\left[\begin{array}{c}{u}_{\mathrm{s\α}}^{*}\\ u_{\mathrm{s\β}}^{*}\end{array}\right]=\left[\begin{array}{cc}-\sin {\mathrm{\θ}}_{\mathrm{\ψ}}& -\cos {\mathrm{\θ}}_{\mathrm{\ψ}}\\ \cos {\mathrm{\θ}}_{\mathrm{\ψ}}& -\sin {\mathrm{\θ}}_{\mathrm{\ψ}}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{sp}}^{*}\\ u_{\mathrm{sq}}^{*}\end{array}\right].$

Embodiment two: below in conjunction with Fig. 4 present embodiment is described, present embodiment is that the calculating to the set-point of the active power of combining inverter in the execution mode one and reactive power further specifies: the active power set-point p of the combining inverter described in three ^*Obtain by following method: with the output voltage U of dc capacitor _DcGiven voltage U with dc capacitor _Dc ^*Relatively, then the comparative result that obtains is regulated the output valve after again the PI closed-loop regulator being regulated and the output voltage U of dc capacitor through the PI closed-loop regulator _DcMultiply each other and acquire active power set-point p ^*The reactive power set-point of the combining inverter described in three is 0.

Present embodiment adopts the dc capacitor voltage outer shroud, two closed loop controlling structures of ring in the power that is incorporated into the power networks, its control method flow process as shown in Figure 4, the reactive power set-point of selected combining inverter is 0, moves with unity power factor with the assurance combining inverter.

Claims (5)

1. the direct Power Control method of a grid-connected inverter without non-AC voltage sensor, it is characterized in that: its control method is:

One, the output that filter is connected in combining inverter carries out filtering to output current, the three-phase electricity flow valuve of combining inverter output is carried out three-phase-two-phase coordinate transform, obtain the component i of three-phase electricity flow valuve under the two-phase rest frame of combining inverter output _αAnd i _βAt the input parallel connection direct electric capacity of combining inverter, with the component u of control voltage given value under the two-phase rest frame of combining inverter _{S α} ^*And u _{S β} ^*Respectively with the voltage U at dc capacitor two ends _DcMultiply each other, obtain the component u of inverter voltage value under the two-phase rest frame of current combining inverter _{S α}And u _{S β}

Two, with the component u of inverter voltage value under the two-phase rest frame of the current combining inverter that obtains in one _{S α}And u _{S β}Carry out integral processing by an integrator that has integration amplitude limit feedback element respectively, obtaining integral result respectively is ψ _{U α}And ψ _{U β}, pass through formula $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{\α}}={\mathrm{\ψ}}_{\mathrm{u\α}}+{\mathrm{Li}}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{\β}}={\mathrm{\ψ}}_{\mathrm{u\β}}+{\mathrm{Li}}_{\mathrm{\β}}\end{array}\right.$ Calculate the component ψ of virtual magnetic linkage under the two-phase rest frame of voltage on line side _αAnd ψ _β, L is the inductance value of filter in the formula;

Three, by the instantaneous power computing formula $\left\{\begin{array}{c}p=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\β}}-{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\α}})\\ q=\mathrm{\ω}({\mathrm{\ψ}}_{\mathrm{\α}}{i}_{\mathrm{\α}}+{\mathrm{\ψ}}_{\mathrm{\β}}{i}_{\mathrm{\β}})\end{array}\right.,$ ω is net top-cross stream voltage angle frequency in the formula, obtain the active power p and the reactive power q of the instantaneous output of combining inverter, described active power p is compared with the active power set-point of combining inverter, obtain comparative result, described reactive power q is compared with the reactive power set-point of combining inverter, obtain comparative result, above-mentioned two comparative results are regulated the back by a closed-loop regulator respectively obtain two magnitudes of voltage, described two magnitudes of voltage are controlled the component u of voltage given value under the two-phase rotating coordinate system as new combining inverter _Sp ^*And u _Sq ^*

Four, by formula ${\mathrm{\θ}}_{\mathrm{\ψ}}=\arctan \frac{{\mathrm{\ψ}}_{\mathrm{\β}}}{{\mathrm{\ψ}}_{\mathrm{\α}}},$ The component ψ of virtual magnetic linkage under the two-phase rest frame according to voltage on line side _αAnd ψ _βCalculate the vectorial angle θ of virtual flux linkage vector _ψ, again with described vectorial angle θ _ψWith three in the component u of combining inverter control voltage given value under the two-phase rotating coordinate system that obtain _Sp ^*And u _Sq ^*Through the conversion of rotation-static coordinate, obtain the component u of control voltage given value under the two-phase rest frame of new combining inverter _{S α} ^*And u _{S β} ^*, with new u _{S α} ^*And u _{S β} ^*Calculate through the space vector of voltage control algolithm, obtain the control signal of each power device of combining inverter, realize direct Power Control combining inverter.

2. the direct Power Control method of grid-connected inverter without non-AC voltage sensor according to claim 1 is characterized in that: the biphase current value i of described combining inverter input _a, i _bObtain by current sensor senses, the third phase current value is according to the three-phase current addition and be zero to obtain.

3. the direct Power Control method of grid-connected inverter without non-AC voltage sensor according to claim 1 is characterized in that: the component u of the inverter voltage value of the current combining inverter described in two under the two-phase rest frame _{S α}And u _{S β}Carry out integral processing by an integrator that has integration amplitude limit feedback element respectively, obtaining integral result respectively is ψ _{U α}And ψ _{U β}, be to pass through formula $\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{u\α}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\α}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{Z}_{\mathrm{\α}}\\ {\mathrm{\ψ}}_{\mathrm{u\β}}=\frac{1}{s+\mathrm{\ω}}{u}_{\mathrm{s\β}}+\frac{\mathrm{\ω}}{s+\mathrm{\ω}}{Z}_{\mathrm{\β}}\end{array}\right.$ Calculate, s is the multiple parameter in the complex frequency domain in the formula, Z _α, Z _βBe ψ _{U α}And ψ _{U β}Through the output valve after the amplitude limit link, Z _α, Z _βInitial value be zero.

4. the direct Power Control method of grid-connected inverter without non-AC voltage sensor according to claim 1 is characterized in that: the active power set-point p of the combining inverter described in three ^*Obtain by following method: with the output voltage U of dc capacitor _DcGiven voltage U with dc capacitor _Dc ^*Relatively, then the comparative result that obtains is regulated the output valve after again the PI closed-loop regulator being regulated and the output voltage U of dc capacitor through the PI closed-loop regulator _DcMultiply each other and acquire active power set-point p ^*

5. the direct Power Control method of grid-connected inverter without non-AC voltage sensor according to claim 1, it is characterized in that: the reactive power set-point of the combining inverter described in three is 0.

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