CN106208054B - Inhibit the device and method of synchronous inverter negative-sequence current under the conditions of unbalanced power supply - Google Patents

Inhibit the device and method of synchronous inverter negative-sequence current under the conditions of unbalanced power supply Download PDF

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CN106208054B
CN106208054B CN201610838831.5A CN201610838831A CN106208054B CN 106208054 B CN106208054 B CN 106208054B CN 201610838831 A CN201610838831 A CN 201610838831A CN 106208054 B CN106208054 B CN 106208054B
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sequence
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positive
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inverter
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CN106208054A (en
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李辉
李磊
彭寒梅
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Xiangtan University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]

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  • Inverter Devices (AREA)

Abstract

The invention discloses a kind of methods for inhibiting synchronous inverter negative-sequence current under the conditions of unbalanced power supply, include the following steps：Network voltage is decomposed into positive sequence and negative sequence component, measurement obtains the amplitude and phase of positive and negative sequence voltage；Establish positive and negative sequence controller；Using the positive and negative sequence voltage of power grid as the tracking object of two controllers, the output signal of two controllers is synthesized to the modulated signal of PWM, drives inverter；The electric current of circuit is subjected to positive-negative sequence decomposition, respectively as the input quantity of positive and negative sequence controller；Positive and negative sequence current feedback is introduced to positive and negative sequence controller, realizes transmission, the inhibition to negative-sequence current for synchronizing rear power.The present invention realizes the negative-sequence current of gird-connected inverter suppression system while normal operation under the conditions of unbalanced source voltage, avoids the influence that negative sequence component is brought to system, reduces the complexity of calculating.The invention also discloses the devices for inhibiting synchronous inverter negative-sequence current under the conditions of a kind of unbalanced power supply.

Description

Inhibit the device and method of synchronous inverter negative-sequence current under the conditions of unbalanced power supply
Technical field
Inhibit to synchronize the present invention relates to three-phase inverter cutting-in control field, more particularly under the conditions of a kind of unbalanced power supply The device and method of inverter negative-sequence current.
Background technology
As the interface of distributed generation system, gird-connected inverter usually converts the electric energy that regenerative resource is sent out to electricity Net acceptable AC energy.There are randomness and fluctuation, generally use maximal power tracings to control for renewable energy power generation, Generally it is not involved in power grid voltage regulating and frequency modulation.Control changes the operation characteristic of gird-connected inverter, and gird-connected inverter is modeled as passing System synchronous generator, can promote adaptability and receiving ability of the power grid to distributed generation resource, inverter is made to simulate synchronous hair The external characteristics of motor, to enable distributed generation resource to participate in mains frequency and voltage adjusting as synchronous generator, quickly It is synchronous and seamlessly and off-network, adverse effect of the reduction distributed energy to power grid.However distributed generation system typically exhibits Light current net state, the case where being susceptible to unbalanced source voltage, the negative sequence component of network voltage will be grid-connected inverse in influence system The normal work for becoming device may cause grid-connected current Severe distortion occur, or even cause inversion system unstability off-grid.Therefore very It is necessary to study inverters under the conditions of a kind of imbalance to work normally, and can effectively inhibit the method for negative-sequence current.
Invention content
Simple, highly practical unbalanced power supply condition is calculated in order to solve the above technical problem, the present invention provides a kind of It is lower to inhibit the method for synchronous inverter negative-sequence current, and provide and inhibit synchronous inverter negative phase-sequence electricity under the conditions of a kind of unbalanced power supply The device of stream.
Technical proposal that the invention solves the above-mentioned problems is：Inhibit synchronous inverter negative phase-sequence under the conditions of a kind of unbalanced power supply The device of electric current, including inverter；Control module；Positive-negative sequence extraction module, positive-negative sequence extraction module include Current Decomposition unit, Inverter output voltage resolving cell and network voltage resolving cell, Current Decomposition unit, inverter output voltage resolving cell, The input terminal of network voltage resolving cell is connected with inverter output end, inverter output end, power grid respectively, Current Decomposition list Member, inverter output voltage resolving cell, the output end of network voltage resolving cell are connected with the input terminal of control module；Control The output end of module connects inverter through PWM drive modules；The control module includes for meeting given output power just Sequence controller and negative phase-sequence controller for inhibiting negative-sequence current.
A kind of method for inhibiting synchronous inverter negative-sequence current under the conditions of unbalanced power supply, includes the following steps：
1) under the conditions of unbalanced power supply, network voltage is decomposed into positive sequence and negative sequence component using symmetrical component method, is surveyed Measure the amplitude and phase information of positive and negative sequence voltage；
2) two controllers, respectively positive sequence, negative phase-sequence control are established according to the principle of synchronous generator and mathematical model Device；
3) using the positive and negative sequence voltage signal of power grid as the tracking object of two controllers, by the output of two controllers Signal synthesizes the modulated signal of PWM, drives inverter output voltage, output voltage is equally decomposed into positive-negative sequence, and is synchronized with The relevant voltage of grid side；With carried out again after synchronized it is grid-connected；
4) electric current of circuit is subjected to positive-negative sequence decomposition after grid-connected, respectively as the electric current of corresponding positive and negative sequence controller Input quantity；
5) it introduces forward-order current and feeds back to positive sequence controller, and carry out power setting in positive sequence controller, realize and synchronize The transmission of power afterwards；Negative phase-sequence controller tracks the negative sequence voltage of power grid, introduces negative-sequence current and feeds back to negative phase-sequence controller, realization pair The inhibition of negative-sequence current.
The method for inhibiting synchronous inverter negative-sequence current under the conditions of above-mentioned unbalanced power supply, in the step 1), using pair Weigh method, does not consider zero-sequence component, three-phase power grid voltage VabcPositive and negative order components are resolved into, wherein positive sequence is expressed as Vabc +, bear Sequence is expressed as Vabc -, carry out calculating as the following formula and acquire；
Vabc +=[T+]Vabc；Vabc -=[T-]Vabc
In formula, [T+] and [T-] it is positive and negative sequence split-matrix, wherein α=ej120=e-j240It is a complex operator, then utilizes the soft of double Second Order Generalized Integrators Part phaselocked loop scheme acquisition divides electric voltage frequency, amplitude and phase after sequence, the subscript of each Parameters in Formula+,-respectively represent just, Negative phase-sequence.
Inhibit the method for synchronous inverter negative-sequence current, the step 2) specific steps under the conditions of above-mentioned unbalanced power supply Positive and negative sequence controller to be established according to Mathematical Models of Synchronous Machine, from the electric network positive and negative sequence information setting controller of extraction Parameter；
According to formulaThe output signal of controller is calculated, is also the defeated of inverter Go out voltage；
In formula：For induced electromotive force；MfFor virtual mutual inductance；ifFor virtual exciting current, i.e., by Mfif It is set as constant；θ is virtual rotor rotational angle；Inverter output and synchronized in order to control, i.e. e=vg, vgFor grid side electricity Pressure, is set as θ by the θ in controllerg,For virtual angular frequency, i.e.,Because of ifFor constant, have SoVgFor vgAmplitude, to establish positive sequence controller, negative phase-sequence controller respectively, output is respectively e+、e-, in positive sequence controllerIn negative phase-sequence controller
Inhibit the method for synchronous inverter negative-sequence current under the conditions of above-mentioned unbalanced power supply, the step 3) is according to power grid Positive-negative sequence voltage signal makes the positive and negative sequence voltage of the output independently tracked power grid of electromotive force of two controllers, makes e respectively+=vg +, e-=vg -, subscript in formula+,-positive and negative sequence is respectively represented, wherein the mathematical model in positive sequence controller isWherein ifConstant is subscript, indicates virtual exciting current ifFor constant；<.,.>Table Show inner product；Mathematical model in negative phase-sequence controller is
The output signal of two controllers is synthesized to the modulated signal of PWM, drives inverter output voltage, output electricity Pressure is equally decomposed into positive-negative sequence, and is synchronized with the relevant voltage of grid side；
Asymmetric three-phase voltageIn, point three representation in components, i.e. positive sequence, negative phase-sequence, zero sequence per phase voltage Algebraical sum, do not consider zero-sequence component,
According to formulaThe synthesis of positive and negative sequence voltage is calculated, in formulaModule exports just in order to control Sequence electromotive force；The negative phase-sequence electromotive force of module output in order to control；For the three-phase electricity electromotive force of synthesis；It willPWM is inputted to drive Dynamic model block controls inverter output, realizes the inverter that an inverter virtually jointly controls for two isochronous controllers.
The method for inhibiting synchronous inverter negative-sequence current under the conditions of above-mentioned unbalanced power supply, in the step 3), in order to make Controller controls inverter output voltage and synchronized, i.e., to ensure the amplitude and frequency and phase of the positive and negative sequence voltage of inverter It is identical as grid side voltage respectively, in negative phase-sequence controller, with reference to negative phase-sequence active powerSimultaneously willAs inverter The rated frequency of negative sequence voltage, thereforeWhereinFor virtual negative phase-sequence machine torque；In the sagging of synchronous inverter In characteristic, sagging coefficient in negative phase-sequence controller is definedΔT-For the change rate of the total Virtual Torque of negative phase-sequence, Δ ω-It is inverse Become the change rate of device negative sequence voltage frequency, you can be expressed as ω-WithDifference, thus calculate Δ T-；Before grid-connected, inverter No current passes through between power grid, according to the mathematical model in negative phase-sequence controllerHaveRoot According to the Virtual Torque equilibrium equation of synchronous inverter WithAnd Δ T-Algebraical sum using 1/Js Module obtains ω-, this process realizes that controller output negative sequence voltage frequency is synchronous with grid side, and ω-It is obtained by integration module The phase angle θ of negative sequence voltage-；
While negative phase-sequence controller control inverter output negative sequence voltage is synchronous with grid side negative sequence voltage, positive sequence control Device equally control is synchronous with grid side positive sequence voltage, and the two is simultaneously through row；In positive sequence controller, with reference to positive sequence active powerAnd reactive powerZero is set to before grid-connected, according to the grid-connected rating formula of synchronous generatorWithWherein XSFor the synchronous impedance of virtual synchronous generator；Work as P When being all zero with Q, there is phase angle θ=θgWith voltage magnitude E=VgTo meet the grid-connected conditions of inverter；It willAs inverter The rated frequency of positive sequence voltage, thereforeWhereinIt is zero before grid-connected for virtual positive sequence machine torque；It is inverse synchronizing Become in the droop characteristic of device, defines sagging coefficient in positive sequence controllerΔT+For the variation of the total Virtual Torque of positive sequence Rate, Δ ω+For the change rate of inverter positive sequence voltage frequency, you can be expressed as ω+WithDifference, it is possible thereby to calculate Δ T+； Before grid-connected, no current passes through between inverter and power grid, according to the mathematical model in positive sequence controllerHaveAnd Q+=0, according to the Virtual Torque equilibrium equation of synchronous inverter WithAnd Δ T+Algebraical sum obtain ω using 1/Js modules+, this process realize controller it is defeated It is synchronous with grid side to go out positive sequence voltage frequency, and ω+The phase angle θ of positive sequence voltage is obtained by integration module+。
Inhibit the method for synchronous inverter negative-sequence current under the conditions of above-mentioned unbalanced power supply, the step 4) is according to after grid-connected Line current, obtain the positive-negative sequence current i divided after sequence using the software phase-lock loop scheme of double Second Order Generalized Integrators+And i-Make For the current reference signal of two controllers.
The method for inhibiting synchronous inverter negative-sequence current under the conditions of above-mentioned unbalanced power supply, in the step 5), in negative phase-sequence In controller, keep original operational mode constant, the negative sequence voltage of inverter tracks the negative sequence voltage of power grid always, keeps pair The inhibition of negative-sequence current, therefore i-It is zero, andIt remains
In positive sequence controller, it is ensured that the normal operation of inverter starts to transmit active power and idle to grid side Active power is set as needed in powerValue, hasIn generator rotor angle 0<δ<Pi/2 has Work(power is expressed as P=Teω,When generator rotor angle δ increases and decreases, TeAlso can increase and decrease therewith；
Assuming that the frequencies omega of power grid positive sequence voltageg +Decline, power angle and electromagnetic torque Te +It will rise, by a product The input of sub-module 1/Js will decline, and inverter exports the frequencies omega of positive sequence voltage+Decline, this process is until ω+=ωg +； Similarly, the frequencies omega of power grid positive sequence voltageg +Rise, same process is until ω+=ωg +；Therefore, when output positive sequence active power When increase, the frequency of positive sequence controller output frequency tracking power grid positive sequence voltage realizes positive sequence voltage frequency modulation, then according to sagging The actual power that Characteristics Control calculates traces into setting power, completes active power and transmits；It is idle to power grid conveying after grid-connected When power, it is set as neededValue, by the Virtual Torque equilibrium equation of synchronous inverterDefinition is just Sagging coefficient in sequence controllerBefore being not introduced into the sagging control of voltage, haveQ+Tracking Qset +There is no error in stable state, but Mfif +It can increase with the increase of the positive sequence reactive power of setting, therefore e+Also can increase Add；After introducing voltage droop control, feedback time is set as needed, and has at this timeWherein K is constant, Vm +For the amplitude of inverter positive sequence voltage, i.e. the output voltage V by measuring inverterabcIt obtains, there is Vg +-Vm +< 0, Mfif +It can reduce according to set proportion again, therefore inverter output positive sequence voltage amplitude is reduced according to set proportion, it is complete It is transmitted at reactive power.
The beneficial effects of the present invention are：
1, in the method for present invention inhibition synchronous inverter negative-sequence current, asymmetric network voltage is decomposed into two first A symmetrical component of voltage, respectively controller corresponding thereto controlled through line trace, realize the decoupling of positive and negative sequence voltage；Then Using the positive and negative sequence voltage signal of power grid as the tracking object of two controllers, the output signal of two controllers is synthesized The modulated signal of PWM drives inverter output voltage, is realized to network voltage by being superimposed to the output of positive and negative sequence controller Effective tracking, and then complete it is grid-connected；The transmission of power is completed after grid-connected, but the transmission of power is in positive sequence controller Operation, thus it is grid-connected after the electric current of circuit is subjected to positive-negative sequence decomposition, it is defeated respectively as the electric current of corresponding positive and negative sequence controller Enter amount, then introduces forward-order current and feed back to positive sequence controller, and carry out power setting in positive sequence controller, after realization synchronizes The transmission of power；Negative phase-sequence controller tracks the negative sequence voltage of power grid, introduces negative-sequence current and feeds back to negative phase-sequence controller, realizes to negative The inhibition of sequence electric current.Entire control process realizes gird-connected inverter and remains able to normally transport under the conditions of unbalanced source voltage Row, the negative-sequence current of energy suppression system, avoids the influence that negative sequence component is brought to system, reduces structure and the complexity of calculating Degree, entire step is easy to implement, highly practical, has certain popularization and application value.
2, it includes control module and positive-negative sequence extraction module that the present invention, which inhibits the device of synchronous inverter negative-sequence current, positive and negative Sequence extraction module to the voltage decomposition of the voltage and inverter of grid side output, obtain respectively corresponding voltage magnitude, phase and Frequency, control module include positive sequence controller and negative phase-sequence controller, and positive sequence controller receives feedback forward-order current and positive sequence power grid Side voltage signal, it is intended that after the synchronizing of power grid positive sequence voltage, controlling it to the normal transmission power of power grid；Negative phase-sequence controller receives Electrical network negative phase-sequence voltage signal and current signal, it is intended that tracking grid side negative sequence voltage signal, the final inhibition for realizing negative-sequence current； The composite signal of positive and negative sequence controller output voltage, control inverter output voltage have power biography again after being synchronized with network voltage It passs, and inhibits negative-sequence current, make inverter that can be worked normally under the conditions of unbalanced power supply.
Description of the drawings
Fig. 1 is the structure diagram of apparatus of the present invention.
Fig. 2 is the flow chart of the method for the present invention.
Fig. 3 is the positive sequence control principle drawing in the method for the present invention.
Specific implementation mode
The present invention is further illustrated with reference to the accompanying drawings and examples.
As shown in Figure 1, inhibiting the device of synchronous inverter negative-sequence current, including inversion under the conditions of a kind of unbalanced power supply Device；Control module；Positive-negative sequence extraction module, positive-negative sequence extraction module utilize the software phase-lock loop scheme of double Second Order Generalized Integrators The voltage decomposition of voltage and inverter output to grid side, obtains corresponding voltage magnitude, phase and frequency, positive-negative sequence respectively Extraction module includes Current Decomposition unit, inverter output voltage resolving cell and network voltage resolving cell, Current Decomposition list Member, inverter output voltage resolving cell and network voltage resolving cell input terminal respectively with inverter output end, inverter Output end, power grid be connected, Current Decomposition unit, inverter output voltage resolving cell and network voltage resolving cell output end It is connected with the input terminal of control module；The output end of control module connects inverter through PWM drive modules,；The control module Including positive sequence controller and negative phase-sequence controller, positive sequence controller receives feedback forward-order current and positive sequence grid side voltage signal, meaning After to the synchronizing of power grid positive sequence voltage, it is controlled to the normal transmission power of power grid；Negative phase-sequence controller receives electrical network negative phase-sequence voltage Signal and current signal, it is intended that tracking grid side negative sequence voltage signal, the final inhibition for realizing negative-sequence current；PWM drive modules Modulated signal using positive and negative sequence controller output voltage composite signal, control inverter output voltage be synchronized with power grid There is power transfer again after voltage, and inhibit negative-sequence current, makes inverter that can be worked normally under the conditions of unbalanced power supply.
A kind of method for inhibiting synchronous inverter negative-sequence current under the conditions of unbalanced power supply, includes the following steps：
1) under the conditions of unbalanced power supply, network voltage is decomposed into positive sequence and negative sequence component using symmetrical component method, is surveyed Measure the amplitude and phase information of positive and negative sequence voltage.
Using symmetrical component method, zero-sequence component, three-phase power grid voltage V are not consideredabcPositive and negative order components are resolved into, wherein just Sequence is expressed as Vabc +, negative phase-sequence is expressed as Vabc -, carry out calculating as the following formula and acquire；
Vabc +=[T+]Vabc；Vabc -=[T-]Vabc
In formula, [T+] and [T-] it is positive and negative sequence split-matrix, wherein α=ej120=e-j240It is a complex operator, then utilizes the soft of double Second Order Generalized Integrators The acquisition of part phaselocked loop scheme divides the electric voltage frequency after sequenceWithAmplitudeWithAnd phase, the subscript of each Parameters in Formula + ,-respectively represent positive and negative sequence.
2) two controllers, respectively positive sequence, negative phase-sequence control are established according to the principle of synchronous generator and mathematical model Device.
Positive and negative sequence controller is established according to Mathematical Models of Synchronous Machine, from the electric network positive and negative sequence information setting control of extraction The parameter of device processed；
According to formulaThe output signal of controller is calculated, is also the defeated of inverter Go out voltage；
In formula：For induced electromotive force；MfFor virtual mutual inductance；ifFor virtual exciting current, i.e., by Mfif It is set as constant；θ is virtual rotor rotational angle；Inverter output and synchronized in order to control, i.e. e=vg, vgFor grid side electricity Pressure, is set as θ by the θ in controllerg,For virtual angular frequency, i.e.,Because of ifFor constant, have SoVgFor vgAmplitude, to establish positive sequence controller, negative phase-sequence controller respectively, output is respectively e+、e-, in positive sequence controllerIn negative phase-sequence controller
3) using the positive and negative sequence voltage signal of power grid as the tracking object of two controllers, by the output of two controllers Signal synthesizes the modulated signal of PWM, drives inverter output voltage, output voltage is equally decomposed into positive-negative sequence, and is synchronized with The relevant voltage of grid side；With carried out again after synchronized it is grid-connected.
According to the positive-negative sequence voltage signal of power grid, make the independently tracked power grid of output electromotive force of two controllers respectively just Negative sequence voltage makes e+=vg +,e-=vg -, subscript in formula+,-positive and negative sequence is respectively represented, wherein the mathematical modulo in positive sequence controller Type isWherein ifConstant is subscript, indicates virtual exciting current ifFor constant；<.,. >Indicate inner product；Mathematical model in negative phase-sequence controller is
The output signal of two controllers is synthesized to the modulated signal of PWM, drives inverter output voltage, output electricity Pressure is equally decomposed into positive-negative sequence, and is synchronized with the relevant voltage of grid side；
Asymmetric three-phase voltageIn, point three representation in components, i.e. positive sequence, negative phase-sequence, zero sequence per phase voltage Algebraical sum, do not consider zero-sequence component,
According to formulaThe synthesis of positive and negative sequence voltage is calculated, in formulaThe positive sequence of module output in order to control Electromotive force；The negative phase-sequence electromotive force of module output in order to control；For the three-phase electricity electromotive force of synthesis；It willInput PWM drivings Module controls inverter output, realizes the inverter that an inverter virtually jointly controls for two isochronous controllers.
Such as Fig. 2 -- shown in 3, in order to make controller control inverter output voltage and synchronized, i.e., to ensure inverter The amplitude and frequency and phase of positive and negative sequence voltage are identical as grid side voltage respectively.Such as part on Fig. 3 dotted lines, in negative phase-sequence controller In, with reference to negative phase-sequence active powerIt is simultaneously will because negative phase-sequence controller is not involved in the transmission of powerIt is negative as inverter The rated frequency of sequence voltage, thereforeWhereinFor virtual negative phase-sequence machine torque.In the sagging spy of synchronous inverter Property in, define negative phase-sequence controller in sagging coefficientΔT-For the change rate of the total Virtual Torque of negative phase-sequence, Δ ω-Inversion The change rate of device negative sequence voltage frequency, you can be expressed as ω-WithDifference, it is possible thereby to calculate Δ T-.Before grid-connected, inversion No current passes through between device and power grid, therefore can be according to the mathematical model in negative phase-sequence controllerHaveAccording to the Virtual Torque equilibrium equation of synchronous inverter WithAnd Δ T-Algebraical sum obtain ω using 1/Js modules-, this process realization controller output negative sequence voltage frequency It is synchronous with grid side, and ω-The phase angle θ of negative sequence voltage is obtained by integration module-.Such as the mathematical model in negative phase-sequence controller In, Mfif -ω-For e-Amplitude, therefore in the synchronizing process of frequency, i.e.,For make inverter negative sequence voltage amplitude with Grid side is identical, and electrical network negative phase-sequence voltage is illustratedWithIndicate the amplitude of grid side voltage, Therefore by amplitudeAnd frequencyPart as the controller inputs, and M is calculated with thisfif -, i.e.,Ensure
While negative phase-sequence controller control inverter output negative sequence voltage is synchronous with grid side negative sequence voltage, positive sequence control Device equally control is synchronous with grid side positive sequence voltage, and the two is simultaneously through row.As shown in Fig. 3 dotted lines positive sequence controller below, With reference to positive sequence active powerAnd reactive powerIt is set to zero before grid-connected, is public according to grid-connected inverters power calculation FormulaWithWherein XSFor the synchronous impedance of virtual synchronous generator； When P and Q are zero, there is phase angle θ=θgWith voltage magnitude E=VgTo meet the grid-connected conditions of inverter.It willAs inversion The rated frequency of device positive sequence voltage, therefore(being zero before grid-connected), whereinFor virtual positive sequence machine torque.In synchronization In the droop characteristic of inverter, sagging coefficient in positive sequence controller is definedΔT+For the change of the total Virtual Torque of positive sequence Rate, Δ ω+The change rate of inverter positive sequence voltage frequency, you can be expressed as ω+WithDifference, it is possible thereby to calculate Δ T+。 Before grid-connected, no current passes through between inverter and power grid, therefore can be according to the mathematical model in positive sequence controllerHaveAnd Q+=0, therefore according to the Virtual Torque equilibrium equation of synchronous inverter WithAnd Δ T+Algebraical sum obtain ω using 1/Js modules+, this process realize controller it is defeated It is synchronous with grid side to go out positive sequence voltage frequency, and ω+The phase angle θ of positive sequence voltage is obtained by integration module+.As positive sequence controls In mathematical model in device, Mfif +ω+For e+Amplitude, therefore in the synchronizing process of frequency, i.e.,To make inverter Positive sequence voltage amplitude is identical as grid side, and power grid positive sequence voltage is illustratedWithIndicate electricity The amplitude of voltage on line side, before grid-connectedQ+All it is zero, reactive power and electricity is not introduced before grid-connected during entire control The sagging mechanism of pressure, the input before 1/Ks is zero.Use amplitudeAnd frequencyTo calculate Mfif +Initialization value, i.e. initial valueIt ensure that
In positive negative controller control inverter with after grid side positive-negative sequence voltage synchronous, positive-negative sequence voltage superposition, i.e. e are carried out+With e-Modulated signal of the synthesis as PWM, realization is grid-connected.
4) it needs to transmit power to grid side after grid-connected, therefore circuit will produce electric current, the electric current of circuit be carried out positive and negative Sequence is decomposed, and the positive-negative sequence current i after dividing sequence is obtained using the software phase-lock loop scheme of double Second Order Generalized Integrators+And i-And by its It feeds back to respectively in corresponding controller.
5) it introduces forward-order current and feeds back to positive sequence controller, and carry out power setting in positive sequence controller, realize and synchronize The transmission of power afterwards；Negative phase-sequence controller tracks the negative sequence voltage of power grid, introduces negative-sequence current and feeds back to negative phase-sequence controller, realization pair The inhibition of negative-sequence current.
In negative phase-sequence controller, keep original operational mode constant, because the negative sequence voltage of inverter tracks electricity always The negative sequence voltage of net keeps the inhibition to negative-sequence current, therefore i-It is zero, andIt remainsIn positive sequence controller, it is ensured that the normal operation of inverter starts to transmit active power and idle work(to grid side Active power is set as needed in rateValue, hasIn generator rotor angle 0<δ<Pi/2, it is active Power is also referred to as P=Teω,When generator rotor angle δ increases and decreases, TeAlso can increase and decrease therewith.Assuming that power grid The frequencies omega of positive sequence voltageg +Decline, power angle and electromagnetic torque Te +It will rise, by the input of an integration module 1/Js It will decline, inverter exports the frequencies omega of positive sequence voltage+Decline, this process is until ω+=ωg +；Similarly, power grid positive sequence voltage Frequencies omegag +Rise, same process is until ω+=ωg +.Therefore, when exporting the increase of positive sequence active power, positive sequence controller Output frequency can track the frequency of power grid positive sequence voltage, realize positive sequence voltage frequency modulation, then be calculated according to droop characteristic control Actual power traces into setting power, completes active power and transmits.When conveying reactive power to power grid after grid-connected, as needed SettingValue, by the Virtual Torque equilibrium equation of synchronous inverterDefine sagging system in positive sequence controller NumberBefore being not introduced into the sagging control of voltage, haveQ+Track Qset +It is not have in stable state Error, but Mfif +It can increase with the increase of the positive sequence reactive power of setting, therefore e+Also can increase；Introduce the sagging control of voltage After system, feedback time is set as needed, and has at this timeWherein K is constant, Vm +For inversion The amplitude of device positive sequence voltage, i.e. the output voltage V by measuring inverterabcIt obtains.There is Vg +-Vm +<0, Mfif +It again can be according to setting Fixed ratio is reduced.Therefore inverter output positive sequence voltage amplitude is reduced according to set proportion so that inverter picture synchronizes hair Motor is such, can adjust output voltage by adjusting virtual excitation, realize amplitude modulation.Finally, positive and negative component of voltage passes through Superposition is used as inverter output voltage modulated signal, and drives corresponding power device action by PWM modulator.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention All any modification, equivalent and improvement etc., should all be included in the protection scope of the present invention made by within refreshing and principle.

Claims (5)

  1. It is based under the conditions of unbalanced power supply 1. inhibiting the method for synchronous inverter negative-sequence current under the conditions of a kind of unbalanced power supply Inhibit the device of synchronous inverter negative-sequence current to realize, inhibits the dress of synchronous inverter negative-sequence current under the conditions of unbalanced power supply It sets including inverter；Control module；Positive-negative sequence extraction module, positive-negative sequence extraction module include that Current Decomposition unit, inverter are defeated Go out voltage decomposition unit and network voltage resolving cell, Current Decomposition unit, inverter output voltage resolving cell, network voltage The input terminal of resolving cell is connected with inverter output end, inverter output end, power grid respectively, Current Decomposition unit, inverter Output voltage resolving cell, the output end of network voltage resolving cell are connected with the input terminal of control module；Control module it is defeated Outlet connects inverter through PWM drive modules；The control module includes the positive sequence controller for meeting given output power With the negative phase-sequence controller for inhibiting negative-sequence current；
    The method of synchronous inverter negative-sequence current is inhibited to include the following steps under the conditions of unbalanced power supply：
    1) under the conditions of unbalanced power supply, network voltage is decomposed into positive sequence and negative sequence component using symmetrical component method, is measured To the amplitude and phase information of positive and negative sequence voltage；
    In the step 1), using symmetrical component method, zero-sequence component, three-phase power grid voltage V are not consideredabcResolve into positive-negative sequence point Amount, wherein positive sequence is expressed as Vabc +, negative phase-sequence is expressed as Vabc -, carry out calculating as the following formula and acquire；
    Vabc +=[T+]Vabc；Vabc -=[T-]Vabc
    In formula, [T+] and [T-] it is positive and negative sequence split-matrix, wherein α=ej120=e-j240It is a complex operator, then utilizes the soft of double Second Order Generalized Integrators Part phaselocked loop scheme acquisition divides electric voltage frequency, amplitude and phase after sequence, the subscript of each Parameters in Formula+,-respectively represent just, Negative phase-sequence；
    2) two controllers, respectively positive sequence, negative phase-sequence controller are established according to the principle of synchronous generator and mathematical model；
    The specific steps are establish positive and negative sequence controller, from the power grid of extraction to the step 2) according to Mathematical Models of Synchronous Machine The parameter of positive-negative sequence information setting controller；
    According to formulaThe output signal of controller is calculated, is also the output of inverter electricity Pressure；
    In formula：For induced electromotive force；MfFor virtual mutual inductance；ifFor virtual exciting current, i.e., by MfifIt is set as Constant；θ is virtual rotor rotational angle；Inverter output and synchronized in order to control, i.e. e=vg, vgFor grid side voltage, θ in controller is set as θg,For virtual angular frequency, i.e.,Because of ifFor constant, haveInstitute WithVgFor vgAmplitude, to establish positive sequence controller, negative phase-sequence controller respectively, output is respectively e+、 e-, in positive sequence controllerIn negative phase-sequence controller
    3) using the positive and negative sequence voltage signal of power grid as the tracking object of two controllers, by the output signal of two controllers The modulated signal of PWM is synthesized, drives inverter output voltage, output voltage is equally decomposed into positive-negative sequence, and is synchronized with power grid The relevant voltage of side；With carried out again after synchronized it is grid-connected；
    4) electric current of circuit is subjected to positive-negative sequence decomposition after grid-connected, is inputted respectively as the electric current of corresponding positive and negative sequence controller Amount；
    5) it introduces forward-order current and feeds back to positive sequence controller, and carry out power setting in positive sequence controller, realization synchronizes rear work( The transmission of rate；Negative phase-sequence controller tracks the negative sequence voltage of power grid, introduces negative-sequence current and feeds back to negative phase-sequence controller, realizes to negative phase-sequence The inhibition of electric current.
  2. 2. inhibiting the method for synchronous inverter negative-sequence current, feature under the conditions of unbalanced power supply according to claim 1 It is：The step 3) makes the output electromotive force of two controllers independently tracked respectively according to the positive-negative sequence voltage signal of power grid The positive and negative sequence voltage of power grid, makes e+=vg +,e-=vg -, subscript in formula+,-positive and negative sequence is respectively represented, wherein in positive sequence controller Mathematical model beWherein ifConstant is subscript, indicates virtual exciting current ifFor Constant；<.,.>Indicate inner product；Mathematical model in negative phase-sequence controller is
    The output signal of two controllers is synthesized to the modulated signal of PWM, drives inverter output voltage, output voltage same Sample is decomposed into positive-negative sequence, and is synchronized with the relevant voltage of grid side；
    Asymmetric three-phase voltageIn, point three representation in components, the i.e. generation of positive sequence, negative phase-sequence, zero sequence per phase voltage Number and, do not consider zero-sequence component,
    According to formulaThe synthesis of positive and negative sequence voltage is calculated, in formulaThe positive sequence of module output is electronic in order to control Gesture；The negative phase-sequence electromotive force of module output in order to control；For the three-phase electricity electromotive force of synthesis；It willInput PWM drive modules Inverter output is controlled, realizes the inverter that an inverter virtually jointly controls for two isochronous controllers.
  3. 3. inhibiting the method for synchronous inverter negative-sequence current, feature under the conditions of unbalanced power supply according to claim 1 It is：In the step 3), in order to make controller control inverter output voltage and synchronized, i.e., to ensure that inverter is positive and negative The amplitude and frequency and phase of sequence voltage are identical as grid side voltage respectively, in negative phase-sequence controller, with reference to negative phase-sequence active powerSimultaneously willAs the rated frequency of inverter negative sequence voltage, thereforeWhereinFor virtual negative phase-sequence machine Tool torque；In the droop characteristic of synchronous inverter, sagging coefficient in negative phase-sequence controller is definedΔT-For negative phase-sequence The change rate of total Virtual Torque, Δ ω-The change rate of inverter negative sequence voltage frequency, you can be expressed as ω-WithDifference, by This calculates Δ T-；Before grid-connected, no current passes through between inverter and power grid, according to the mathematical model in negative phase-sequence controllerHaveAccording to the Virtual Torque equilibrium equation of synchronous inverter WithAnd Δ T-Algebraical sum obtain ω using 1/Js modules-, this process realize controller output negative sequence voltage frequency with Grid side synchronizes, and ω-The phase angle θ of negative sequence voltage is obtained by integration module-；
    While negative phase-sequence controller control inverter output negative sequence voltage is synchronous with grid side negative sequence voltage, positive sequence controller is same Sample control is synchronous with grid side positive sequence voltage, and the two is carried out at the same time；In positive sequence controller, with reference to positive sequence active power And reactive powerZero is set to before grid-connected, according to the grid-connected rating formula of synchronous generator WithWherein XSFor the synchronous impedance of virtual synchronous generator；When P and Q are zero, have Phase angle θ=θgWith voltage magnitude E=VgTo meet the grid-connected conditions of inverter；It willAs the specified of inverter positive sequence voltage Frequency, thereforeWhereinIt is zero before grid-connected for virtual positive sequence machine torque；In the droop characteristic of synchronous inverter In, define sagging coefficient in positive sequence controllerΔT+For the change rate of the total Virtual Torque of positive sequence, Δ ω+For inversion The change rate of device positive sequence voltage frequency, you can be expressed as ω+WithDifference, it is possible thereby to calculate Δ T+；Before grid-connected, inversion No current passes through between device and power grid, according to the mathematical model in positive sequence controllerHave And Q+=0, according to the Virtual Torque equilibrium equation of synchronous inverter WithAnd Δ T+Algebraical sum ω is obtained using 1/Js modules+, this process realizes that controller output positive sequence voltage frequency is synchronous with grid side, and ω+By product Sub-module obtains the phase angle θ of positive sequence voltage+。
  4. 4. inhibiting the method for synchronous inverter negative-sequence current, feature under the conditions of unbalanced power supply according to claim 1 It is：The step 4) utilizes the software phase-lock loop scheme of double Second Order Generalized Integrators to obtain according to the line current after grid-connected Divide the positive-negative sequence current i after sequence+And i-Current reference signal as two controllers.
  5. 5. inhibiting the method for synchronous inverter negative-sequence current under the conditions of unbalanced power supply as described in claim 1, feature exists In：In the step 5), in negative phase-sequence controller, keep original operational mode constant, the negative sequence voltage of inverter always with The negative sequence voltage of track power grid keeps the inhibition to negative-sequence current, therefore i-It is zero, andIt remains
    In positive sequence controller, it is ensured that the normal operation of inverter starts to transmit active power and reactive power to grid side, Active power is set as neededValue, hasIn generator rotor angle 0<δ<Pi/2, active power It is expressed as P=Teω,When generator rotor angle δ increases and decreases, TeAlso can increase and decrease therewith；
    Assuming that the frequencies omega of power grid positive sequence voltageg +Decline, power angle and electromagnetic torque Te +It will rise, by an integration module The input of 1/Js will decline, and inverter exports the frequencies omega of positive sequence voltage+Decline, this process is until ω+=ωg +；Similarly, electric The frequencies omega of net positive sequence voltageg +Rise, same process is until ω+=ωg +；Therefore, when exporting the increase of positive sequence active power, The frequency of positive sequence controller output frequency tracking power grid positive sequence voltage, realizes positive sequence voltage frequency modulation, then according to droop characteristic control The actual power that system calculates traces into setting power, completes active power and transmits；When conveying reactive power to power grid after grid-connected, It is set as neededValue, by the Virtual Torque equilibrium equation of synchronous inverterDefine positive sequence controller In sagging coefficientBefore being not introduced into the sagging control of voltage, haveQ+Track Qset +In stable state When there is no error, stillIt can increase with the increase of the positive sequence reactive power of setting, therefore e+Also can increase；Introduce voltage After droop control, feedback time is set as needed, and has at this timeWherein K is constant, Vm + For the amplitude of inverter positive sequence voltage, i.e. the output voltage V by measuring inverterabcIt obtains, there is Vg +-Vm +<0, Mfif +It again can be by It is reduced according to the ratio of setting, therefore inverter output positive sequence voltage amplitude is reduced according to set proportion, completes reactive power and pass It passs.
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CN107425533B (en) * 2017-09-08 2020-06-02 湘潭大学 Method for guiding synchronization inverter in grid-connected operation state when voltage is unbalanced
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104901322A (en) * 2015-05-22 2015-09-09 国家电网公司 Current transformer virtual synchronization control system under asymmetric power grid voltage and method thereof
CN104934992A (en) * 2015-06-23 2015-09-23 国家电网公司 Subsynchronous oscillation suppression device and method based on phase-locked loop error
CN105098804A (en) * 2015-07-08 2015-11-25 国家电网公司 Method and device for controlling three-phase unbalanced current of virtual synchronous generator
CN105305491A (en) * 2015-11-03 2016-02-03 国家电网公司 Virtual synchronous generator-based photovoltaic power control strategy
KR20160064695A (en) * 2014-11-28 2016-06-08 서울과학기술대학교 산학협력단 Apparatus and method for detecting phase and harmonic using fast fourier transform
CN105811400A (en) * 2016-03-18 2016-07-27 国网上海市电力公司 Self-adaptive control method for modes of low-voltage microgrid

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160064695A (en) * 2014-11-28 2016-06-08 서울과학기술대학교 산학협력단 Apparatus and method for detecting phase and harmonic using fast fourier transform
CN104901322A (en) * 2015-05-22 2015-09-09 国家电网公司 Current transformer virtual synchronization control system under asymmetric power grid voltage and method thereof
CN104934992A (en) * 2015-06-23 2015-09-23 国家电网公司 Subsynchronous oscillation suppression device and method based on phase-locked loop error
CN105098804A (en) * 2015-07-08 2015-11-25 国家电网公司 Method and device for controlling three-phase unbalanced current of virtual synchronous generator
CN105305491A (en) * 2015-11-03 2016-02-03 国家电网公司 Virtual synchronous generator-based photovoltaic power control strategy
CN105811400A (en) * 2016-03-18 2016-07-27 国网上海市电力公司 Self-adaptive control method for modes of low-voltage microgrid

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
两级式光伏并网逆变系统控制策略研究;何丽君;《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》;20160615(第06期);第17,26-29,35-44页 *

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