CN104143837A - Alternating-voltage-sensor-free control method for inverter with parameter adaptive characteristic - Google Patents

Abstract

The invention provides an alternating-voltage-sensor-free control method for an inverter with the parameter adaptive characteristic. The method includes the steps that firstly, a quadrature filter is established for the zero-difference following characteristic of specific frequency alternating current signals through a second order generalized integrator, the quadrature filter is used and the parameter adaptive control policy is introduced, a voltage observer of the three-phase grid-connected inverter with the parameter adaptive characteristic is established, under a two-phase static coordinate system, measured power grid side current signals and inverter controller output bridge terminal voltage reference signals serve as input of the voltage observer, and then power grid voltages are observed; in combination with PR control of the three-phase grid-connected inverter under the two-phase static coordinate system, operational control over the inverter under the alternating-voltage-sensor-free condition is achieved. By the adoption of the method, under the condition that control stability of the inverter is kept, the problems of integral saturation, initial value sensitivity, static errors and the like probably existing in conventional alternating-voltage-sensor-free control are solved, and good adaptability is achieved when the grid-connected impedance parameters of the inverter change.

Description

There is the inverter alternating voltage sensorless control method of parameter adaptive characteristic

Technical field

The present invention relates to a kind of control method of three-phase grid-connected inverter.

Background technology

Regenerative resource grid-connected system development in recent years is rapid, in the time of the comparatively weak power distribution network of its access electrical network end or grid structure, may exist and site capacity of short circuit less, grid stability is poor, and electrical network exists comparatively serious voltage fluctuation, flickering, symmetry or asymmetrical voltage to fall the problems such as fault.The intermittence of regenerative resource self and randomness likely further worsen the voltage stability of the electric power system that accesses, and affect conversely the stable operation of self.In order to realize grid-connected power and the Current Control of renewable energy system, in existing grid-connected converter or inverter, the general phase-locked loop that adopts obtains line voltage information, but this class phase-locked loop control is easily subject to the impact of voltage ripple of power network, easily reduce the quality of power supply of regenerative resource grid-connected system.Therefore, some researchers of recent domestic begin one's study and do not rely on the alternating voltage sensorless control of mains voltage signal, to improve the robustness of grid-connected inverters control.

Voltage sensor control is similar with having, and in Converter Without Voltage Sensor control algolithm, the voltage of reconstruct/virtual magnetic linkage signal can be explicit, the row vector control of going forward side by side; Also can be implicit expression, and carry out direct Power Control.Existing line voltage/virtual magnetic linkage reconstructing method roughly can be divided into two classes, the one, line voltage/virtual magnetic linkage reconstructing method of estimating based on complex power, belongs to open loop method of estimation, and accuracy is not high, and owing to containing current differential item, thereby easily cause interference; The 2nd, the line voltage/virtual magnetic linkage reconstructing method based on current on line side bias adjustment, belongs to closed loop method of estimation, and accuracy is higher.

The people such as T.Noguchi have proposed the direct Power Control method based on Converter Without Voltage Sensor in document " Direct power control of PWM converter without power-source voltage sensors ", first this method is used filter inductance electric current and differential term estimation thereof to obtain the meritorious reactive power of AC, then carries out line voltage reconstruct.The error causing in order to reduce differential term, this method needs larger inductance value and sample frequency; In addition, when electric current hour, voltage estimated accuracy can be a greater impact.The people such as Malinowski propose to use instead integral operation in document " Sensorless control strategies for three-phase PWM rectifiers ", observation electrical network " virtual magnetic linkage "; But pure integrator method exist integration saturated with the problem such as null offset, and comparatively responsive to initial value.

Patent CN201010109338.2 proposes a kind of direct Power Control method of grid-connected inverter without non-AC voltage sensor, solve existing method due to the integrator initial value in the virtual flux observer of voltage on line side vector choose improper, and the problem that causes combining inverter normally to work.Patent CN201010207412.4 proposes a kind of control method of alternating voltage sensorless high voltage direct current transmission converter, by the virtual flux linkage vector of computing system, realizes alternating voltage sensorless control.

Alternating voltage sensorless control method described in above-mentioned document and patent is used the scheme based on flux observer conventionally: under synchronous coordinate system, electric current is carried out to integration, thereby obtain " virtual magnetic linkage ", and indirect calculation goes out line voltage angle.In order to reduce to disturb, improve accuracy of observation, generally need to use low pass filter, but the problems such as low pass filter itself exists that null offset, integration are saturated, steady-state error and initial value sensitivity; In the time that line voltage is asymmetric, the cascade algorithm that flux observation separates with positive-negative sequence has increased time of delay, has reduced the dynamic responding speed of system in addition.

Due to second order improper integral device (Second Order Generalized Integrator, SOGI) can carry out integral operation to the of ac of characteristic frequency, therefore be often used to build the phase-locked loop under rest frame, for grid-connected Synchronization Control single-phase or three-phase voltage source type inverter.In fact, second order improper integral device can be used to build a kind of orthogonal filter (Quadrature Filter, QF), export the orthogonal signalling of an offset of sinusoidal, and for the reconstruct of line voltage, thereby realize alternating voltage sensorless control, its advantage is quick, floating, insensitive to initial value, the voltage observer that this orthogonal filter builds simultaneously can adapt to the variation of grid-connected impedance parameter by the improvement of control strategy, thereby can solve well the problem existing in existing alternating voltage sensorless control.In addition, utilize orthogonal signalling can also synchronously realize positive-negative sequence and separate, thereby improve the dynamic property of inverter under asymmetric electrical network condition.

Summary of the invention

The object of the invention is to overcome that null offset, the integration that in the control of existing inverter alternating voltage sensorless, may exist are saturated, the problem such as steady-state error and initial value sensitivity, and make the control of inverter alternating voltage sensorless can adapt to the variation of grid-connected impedance parameter, a kind of three-phase grid-connected inverter alternating voltage sensorless control method with parameter adaptive characteristic is proposed.The present invention can be in the situation that keeping inverter control stability, avoid the problems such as the integration that may occur in conventional alternating voltage sensorless control is saturated, have fast, floating, to advantages such as initial value are insensitive, grid-connected impedance parameter is changed and has good adaptability simultaneously.

A kind of inverter alternating voltage sensorless control method with parameter adaptive characteristic of the present invention, build orthogonal filter based on second order improper integral device (SOGI), then based on this orthogonal filter and introduce parameter adaptive control strategy and build and there is the line voltage observer of parameter adaptive characteristic, this voltage observer is applied in the controller of three-phase grid-connected inverter, realizes the alternating voltage sensorless control of inverter.Specifically comprise the following steps:

1, build the orthogonal filter (QF) based on second order improper integral device (SOGI), the second order resonance link that this second order improper integral device has comprised sinusoidal signal, can carry out " integration " computing by offset of sinusoidal of ac, can realize floating to the AC signal of characteristic frequency and follow the tracks of control.This orthogonal filter comprises the parts such as input/output signal, filter gain coefficient, second order improper integral device, output feedback, and wherein v is filter input signal, with for the output signal of filter, with pair of orthogonal signal, wherein with v same-phase, lag behind 90 ° than v, k is filter gain coefficient.Ac input signal v enters after filter, with the output signal of feedback deviation, device gain coefficient k after filtering, then enters second order improper integral device, second order improper integral device output with

2, the orthogonal filter based on described in step 1 introduce parameter adaptive control strategy, builds the voltage observer with parameter adaptive characteristic, and ac grid voltage is observed.The described voltage observer with parameter adaptive characteristic be input as i _{α β}and v _{α β}, wherein i _{α β}for the inverter ac-side current that measures is at the component of two-phase rest frame, v _{α β}for the bridge end control voltage of circuit control device output is at the component of two-phase rest frame; Output for the line voltage that obtains of observation is at the component of two-phase rest frame.Inverter ac-side current is at the component i of two-phase rest frame _{α β}with the component v of circuit control device bridge end control voltage in two-phase rest frame _{α β}enter respectively the orthogonal filter described in step 1, obtain output with with then the Mathematical Modeling based on three-phase grid-connected inverter $\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=L\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+R\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+\left[\begin{array}{c}{v}_{\mathrm{\α}}\\ v_{\mathrm{\β}}\end{array}\right]$ Derivation obtains the component of line voltage in two-phase rest frame

Based on the orthogonal filter described in step 1, introduce impedance parameter ADAPTIVE CONTROL.Described grid-connected impedance parameter ADAPTIVE CONTROL, be in the time that inverter DC load is constant, make the operation of inverter unity power factor, with the inductance parameters in little step-size change voltage observer, when inverter ac-side current amplitude hour, think that inductance parameters and actual value match.Go out parameter search program min{|i|} according to this Strategy Design, make the i of voltage observer input _{α β}enter min{|i|} search utility, obtain current amplitude resistance value hour, this resistance value is the grid-connected resistance value of inverter reality.Based on the method, make described voltage observer there is parameter adaptive characteristic.

3, the voltage observer with parameter adaptive characteristic based on step 1 and step 2 is applied to the PR controller of three-phase grid-connected inverter under α β coordinate system.This PR controller comprises the link such as the power outer shroud based on PI and the current inner loop based on PR, PWM modulation, wherein power outer shroud comprises DC voltage outer shroud and reactive power outer shroud, control respectively DC voltage and reactive power, the meritorious reference current of DC voltage outer shroud output inverter control, the idle reference current of reactive power outer shroud output inverter control; Current inner loop is the PR controller under α β two-phase rest frame.The line voltage of voltage observer output is at the component of two-phase rest frame following aspect for inverter control: 1. for calculating the actual reactive power value of three-phase grid-connected inverter, as the value of feedback of reactive power outer shroud; 2. be tied to the coordinate transform of α β coordinate system for dq coordinate, the current reference value under the dq coordinate system of power outer shroud PI controller output is transformed to the current reference value under α β coordinate system.Thereby realize the three-phase grid-connected inverter alternating voltage sensorless control based on the method for the invention.

Brief description of the drawings

Fig. 1 combining inverter simple equivalent circuit model;

Fig. 2 combining inverter steady operation phasor diagram, wherein Fig. 2 a is the stable state phasor diagram of inductance parameters when larger than actual value, Fig. 2 b is inductance parameters than the stable state phasor diagram of actual value hour;

Fig. 3 orthogonal filter (QF) structured flowchart;

Fig. 4 has the voltage observer structured flowchart of parameter adaptive characteristic;

Fig. 5 has the three-phase grid-connected inverter alternating voltage sensorless control block diagram of parameter adaptive characteristic;

Simulation result on the impact of invertor operation situation when grid-connected impedance parameter changes in Fig. 6 line voltage observer, wherein Fig. 6 a is that inductance parameters changes, and Fig. 6 b is that voltage magnitude changes, and Fig. 6 c is that current amplitude changes, and Fig. 6 d is inverter output reactive power.

Embodiment

Further illustrate the present invention below in conjunction with the drawings and specific embodiments.

With the comparison of conventional three-phase grid-connected inverter control method, alternating voltage sensorless control method proposed by the invention is not used AC voltage sensor, and use the voltage observer building based on orthogonal filter to obtain line voltage information, this voltage observer has parameter adaptive simultaneously, thereby realize the operation control of three-phase grid-connected inverter under alternating voltage sensorless condition, and this alternating voltage sensorless control method in the time that changing, grid-connected inverters impedance parameter has good adaptability.

The present invention is based on second order improper integral device (SOGI) and build orthogonal filter, then based on this orthogonal filter and introduce parameter adaptive control strategy, structure has the line voltage observer of parameter adaptive characteristic, this voltage observer is applied in the controller of three-phase grid-connected inverter, realizes the alternating voltage sensorless control of inverter.

Described voltage observer can draw according to the model inference of three-phase grid-connected inverter, be shown below:

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=L\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+R\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+\left[\begin{array}{c}{v}_{\mathrm{\α}}\\ v_{\mathrm{\β}}\end{array}\right]---\left(1\right)$

Wherein, u _αand u _β, i _αand i _β, v _αand v _βbe respectively line voltage, inverter ac-side current and the inverter leg output voltage component in two-phase rest frame, L and R are respectively inverter outlet side equivalent inductance and resistance.

In formula (1), there is the differential term of electric current, in general calculating, easily introduce and disturb.This is also that common alternating voltage sensorless control transfers to adopt integral operation, and calculating electrical network " virtual magnetic linkage " also obtains the reason of line voltage information indirectly; The problems such as but conventional " virtual magnetic linkage " method exists, and null offset, integration are saturated, steady-state error and initial value sensitivity, and dynamic response is slower.The present invention is based on second order improper integral device and build orthogonal filter, use this orthogonal filter and introduce a kind of parameter adaptive control strategy and build line voltage observer, can solve preferably current differential operational problem, effectively reduce humorous wave interference, and the three-phase grid-connected inverter alternating voltage sensorless control realizing based on this voltage observer has good dynamic responding speed, grid-connected impedance parameter is changed and has certain adaptability.

Observing formula (1) can find, accurately observe line voltage, not only needs the ac current measurement value that has precision higher, also needs inverter device reactor parameter accurately.In actual motion, the inductance of reactor is difficult to Measurement accuracy, and can change along with the variation of the environmental factors such as temperature.In addition, in the time that grid-connected inverters is worked, the equiva lent impedance of circuit also often changes along with the variation of the factor such as trend, network configuration, thereby affects grid-connected point voltage, and to line voltage, observation has a negative impact.Therefore the present invention's research passes through to improve the parameter adaptive characteristic of voltage observer, thus grid adaptability when raising alternating voltage sensorless is controlled at circuit parameter variations.

Below describe the implementation step of control method of the present invention in detail:

Step (1): first analyze the impact that grid-connected inverters impedance parameter changes

For the impact of circuit parameter is described, can utilize simple equivalent circuit model as shown in Figure 1, and to making following several presupposition in this simplified model:

(1) inverter access forceful electric power net, line voltage u is constant, merges by line impedance and reactor impedance;

(2) ignore the resistance of switching loss and wave filter on AC side;

(3) inverter direct-flow side connects a constant resistance load, and controls DC voltage U _dcremain unchanged, DC side power output P is constant.According to the real component i of the known ac-side current i of alternating current-direct current power relation _dconstant:

Wherein for and the power-factor angle of site, I _loadfor DC side electric current, Const is expressed as a certain constant.

(4) control inverter unity power factor operation.In the time of inverter stable operation, circuit control device is by the line voltage of observer output be directed to axle, due to the effect of current regulator, power network current just equal reference value, can obtain through deriving:

$\begin{array}{c}\left[\begin{array}{c}{\hat{i}}_d\\ {\hat{i}}_q\end{array}\right]=\left[\begin{array}{c}{i}_d^{*}\\ i_q^{*}\end{array}\right]=\frac{1}{{\hat{u}}_d^2+{\hat{u}}_q^2}\left[\begin{array}{cc}{\hat{u}}_d& {\hat{u}}_q\\ {\hat{u}}_q& -{\hat{u}}_d\end{array}\right]\left[\begin{array}{c}{P}^{*}\\ Q^{*}\end{array}\right]\\ =\frac{1}{{\hat{u}}_d^2}\left[\begin{array}{cc}{\hat{u}}_d& 0\\ 0& -{\hat{u}}_d\end{array}\right]\left[\begin{array}{c}{P}^{*}\\ 0\end{array}\right]=\left[\begin{array}{c}{P}^{*}/{\hat{u}}_{\mathrm{gd}}\\ 0\end{array}\right]\end{array}---\left(3\right)$

Wherein, for controller exists line voltage under coordinate system and electric current.

Because electric current can measure by instrument transformer, therefore i overlaps with actual current.According to formula (3), should be zero with the angle of i.Phasor relation figure can obtain inductance parameters and depart from actual value according to Fig. 1 again time, as shown in Figure 2, wherein Fig. 2 a is the stable state phasor diagram of inductance parameters when larger than actual value, Fig. 2 b is inductance parameters than the stable state phasor diagram of actual value hour.Wherein line voltage u, alternating current real component i _dfor steady state value. the inductance parameters using for circuit control device, and L is actual inductance value.As can be seen from Fig. 2, owing to having used incorrect inductance parameters, cause the line voltage of observer output not overlap with virtual voltage, thus actual power factor angle non-vanishing.Due to and the actual reactive power of site non-vanishing, and active power only depends on DC side, no matter therefore larger or little than L, actual current all can increase.

Therefore when the grid-connected impedance parameter value and the actual value that use when circuit control device are inconsistent, can pass through to judge inverter ac-side current amplitude, revise grid-connected impedance parameter.

Step (2): build orthogonal filter (QF) based on second order improper integral device (SOGI).

Second order improper integral device can be realized the tracking to characteristic frequency of ac, is used to the earliest export the of ac of pair of orthogonal, separates to realize positive-negative sequence.According to the feature of its output signal, the filter building based on second order improper integral device is called orthogonal filter (QF) by the present invention, and its structure as shown in Figure 3.

As shown in Figure 3, v is filter input signal, with for output signal, subscript " ^ " represents observed quantity, ω _vfor the angular frequency of ac voltage signal, k is filter gain coefficient.

Step (3): the orthogonal filter based on step (2) is also introduced parameter adaptive control strategy, builds the voltage observer with parameter adaptive characteristic.

Because the orthogonal signalling of sinusoidal signal are equivalent to homophase or the inversion signal of its differential, therefore can derive and obtain following formula based on formula (1):

$\begin{array}{c}\left[\begin{array}{c}{\hat{u}}_{\mathrm{\α}}\\ {\hat{u}}_{\mathrm{\β}}\end{array}\right]=L\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{\hat{i}}_{\mathrm{\α}}\\ {\hat{i}}_{\mathrm{\β}}\end{array}\right]+R\left[\begin{array}{c}{\hat{i}}_{\mathrm{\α}}\\ {\hat{i}}_{\mathrm{\β}}\end{array}\right]+\left[\begin{array}{c}{\hat{v}}_{\mathrm{\α}}\\ {\hat{v}}_{\mathrm{\β}}\end{array}\right]\\ =-L\left[\begin{array}{c}{\hat{i}}_{\mathrm{\α}}^{\⊥}\\ {\hat{i}}_{\mathrm{\β}}^{\⊥}\end{array}\right]+R\left[\begin{array}{c}{\hat{i}}_{\mathrm{\α}}\\ {\hat{i}}_{\mathrm{\β}}\end{array}\right]+\left[\begin{array}{c}{\hat{v}}_{\mathrm{\α}}\\ {\hat{v}}_{\mathrm{\β}}\end{array}\right]\\ =-G_{\mathrm{QF}2}L\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+G_{\mathrm{QF}1}(R\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+\left[\begin{array}{c}{v}_{\mathrm{\α}}\\ v_{\mathrm{\β}}\end{array}\right])\\ =G_{\mathrm{VO}}{\left[\begin{array}{cccc}{i}_{\mathrm{\α}}& i_{\mathrm{\β}}& i_{\mathrm{\α}}& i_{\mathrm{\β}}\end{array}\right]}^T\end{array}---\left(4\right)$

Wherein i _α, i _βfor the inverter ac-side current that measures is at the component of two-phase rest frame, v _α, v _βfor the bridge end control voltage of circuit control device output is at the component of two-phase rest frame; Output for the line voltage that obtains of observation is at the component of two-phase rest frame. with with for i _α, i _βoutput variable after the described orthogonal filter of step (2), subscript " ^ " represents observed quantity, wherein with with orthogonal signalling each other; with with for v _α, v _βoutput variable after the described orthogonal filter of step (2) respectively, wherein with with orthogonal signalling each other; G _vOfor the transfer function of line voltage observer.

Simultaneously described in integrating step (2) can orthogonal filter, introduce impedance parameter ADAPTIVE CONTROL.Described parameter adaptive control strategy, be in the time that inverter DC load is constant, make the operation of inverter unity power factor, with the inductance parameters in little step-size change voltage observer, when inverter ac-side current amplitude hour, think that inductance parameters and actual value match.Go out parameter search program min{|i|} according to this Strategy Design, make the i of voltage observer input _{α β}enter min{|i|} search utility, obtain current amplitude resistance value hour, this resistance value is actual grid-connected resistance value.Based on the method, make described voltage observer there is parameter adaptive characteristic for the variation of grid-connected impedance.

Based on formula (4) and introduce the control block diagram of the voltage observer of impedance parameter ADAPTIVE CONTROL, as shown in Figure 4, can realize the observation to ac grid voltage, there is certain adaptability for the variation of grid-connected inverters impedance parameter simultaneously.

Step (4): the voltage observer with parameter adaptive characteristic of step (3) is applied in the PR controller of three-phase grid-connected inverter under two-phase rest frame, realizes the alternating voltage sensorless control of inverter.

Control block diagram by voltage observer substitution three-phase grid-connected inverter under α β coordinate system, can realize the alternating voltage sensorless control of three-phase grid-connected inverter, as shown in Figure 5.Voltage observer PAVO wherein for step (3) propose a kind of have parameter adaptive characteristic voltage observer, under two-phase rest frame, the bridge end reference voltage signal of the grid side current signal that utilization measures and circuit control device output, observes line voltage information.As shown in Figure 5, K _cfor current controller, the present invention uses conventional PR controller.

For verifying the validity of control method of the present invention, in MATLAB, set up inverter time domain simulation model, as shown in Figure 5, simulation result is as shown in Figure 6 for the control block diagram adopting.Keep DC voltage stability, the active power load of inverter is about 0.5p.u., and reactive power reference qref is made as 0.Make the inductance parameters variation triangular in shape in voltage observer, as shown in Figure 6 a, also will there is cyclic variation in inverter device output current and reactive power, as shown in Fig. 6 b～6d, wherein Fig. 6 b is the comparison of actual electric network voltage magnitude (U) and voltage observer output voltage amplitude (U.ob); Fig. 6 c is inverter device output current amplitude; Fig. 6 d is inverter output reactive power.By more known, inverter output current minimum value appears at inductance and approaches the moment of rated value, and reactive power period of change is identical with inductance period of change, and the amplitude period of change of electric current and observation voltage is the twice of inductance period of change.Simulation result is consistent with theory analysis.

Claims (5)

1. one kind has the inverter alternating voltage sensorless control method of parameter adaptive characteristic, it is characterized in that, first described control method builds orthogonal filter based on second order improper integral device (SOGI), then based on this orthogonal filter and introduce parameter adaptive control strategy and build and there is the line voltage observer of parameter adaptive characteristic, described voltage observer is applied in the PR controller of three-phase grid-connected inverter under two-phase rest frame, realizes the alternating voltage sensorless control of inverter.

2. inverter alternating voltage sensorless control method according to claim 1, it is characterized in that, the second order resonance link that described second order improper integral device comprises sinusoidal signal, can carry out " integration " computing by offset of sinusoidal of ac, can realize floating to the AC signal of characteristic frequency and follow the tracks of control.

3. inverter alternating voltage sensorless control method according to claim 1, is characterized in that, described orthogonal filter comprises input/output signal, filter gain coefficient, second order improper integral device and output feedback; Ac input signal v enters after described orthogonal filter, with the output signal of feedback deviation, device gain coefficient k after filtering, then enters second order improper integral device, second order improper integral device output with

4. according to the inverter alternating voltage sensorless control method described in claim 1 or 3, it is characterized in that, the described voltage observer with parameter adaptive characteristic be input as i _{α β}and v _{α β}, wherein i _{α β}for the inverter ac-side current that measures is at the component of two-phase rest frame, v _{α β}for the bridge end control voltage of circuit control device output is at the component of two-phase rest frame; for the line voltage of voltage observer output is at the component of two-phase rest frame.

Component i by the inverter ac-side current measuring in two-phase rest frame _{α β}with the bridge end control voltage of the circuit control device output component v in two-phase rest frame _{α β}by described orthogonal filter, obtain exporting respectively with with then the Mathematical Modeling based on following three-phase grid-connected inverter:

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=L\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+R\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]+\left[\begin{array}{c}{v}_{\mathrm{\α}}\\ v_{\mathrm{\β}}\end{array}\right]$

Derivation obtains the component of line voltage in two-phase rest frame

Described parameter adaptive control strategy, be in the time that DC load is constant, make the operation of inverter unity power factor, with the inductance parameters in little step-size change voltage observer, when inverter ac-side current amplitude hour, think that inductance parameters and actual value match; Go out parameter search program according to this Strategy Design, make voltage observer there is parameter adaptive characteristic for the variation of grid-connected impedance.

5. inverter alternating voltage sensorless control method according to claim 1, it is characterized in that, the described voltage observer with parameter adaptive characteristic is applied in the PR controller of three-phase grid-connected inverter under α β coordinate system, and this controller comprises the power outer shroud based on PI and the current inner loop based on PR; Voltage observer output for the following aspect of inverter control, realize the alternating voltage sensorless control to three-phase grid-connected inverter:

1. for calculating the actual reactive power value of three-phase grid-connected inverter, as the value of feedback of reactive power outer shroud;

2. be tied to the coordinate transform of α β coordinate system for dq coordinate, the current reference value under the dq coordinate system of power outer shroud PI controller output is transformed to the current reference value under α β coordinate system.