CN103001250A - Compound control method of photovoltaic grid-connected inverter - Google Patents
Compound control method of photovoltaic grid-connected inverter Download PDFInfo
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- CN103001250A CN103001250A CN2012104694154A CN201210469415A CN103001250A CN 103001250 A CN103001250 A CN 103001250A CN 2012104694154 A CN2012104694154 A CN 2012104694154A CN 201210469415 A CN201210469415 A CN 201210469415A CN 103001250 A CN103001250 A CN 103001250A
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention discloses a compound control method of a photovoltaic grid-connected inverter. The compound control method comprises the steps of performing 3s/2r transformation on input current and establishing a grid-connected inverter model under a d-q coordinate system; and utilizing a compound controller to control output current to eliminate even harmonic component disturbance in the output current, wherein the compound controller comprises a proportional plus integral (PI) controller and a repetitive controller which are connected in parallel. By means of the technical scheme that the 3s/2r transformation is performed on the input current, and the compound controller composed of the PI controller and the repetitive controller which are connected in parallel is utilized to eliminate the even harmonic component disturbance in the output current, dynamic response of a system is increased, accuracy and stability are high, harmonic component disturbance can be controlled well, steady-state errors can be eliminated, and the grid-connected current control effect is good.
Description
Technical field
The present invention relates to the photovoltaic combining inverter technical field, be specifically related to a kind of photovoltaic combining inverter composite control method.
Background technology
The control of combining inverter is the key of whole grid-connected control, and the stage photovoltaic single combining inverter need to be finished unsteady flow simultaneously, control and MPPT maximum power point tracking are incorporated into the power networks.
For combining inverter, typical control strategy is the control that realizes active power and reactive power by the output current vector is controlled.In single-stage photovoltaic grid-connected inverter, voltage oriented vector control is basic skills.When control combining inverter output current and line voltage same-phase, can realize the operation of combining inverter unity power factor; When control combining inverter output current is ahead of line voltage, realizing to carry out reactive power compensation to electrical network when combining inverter generates electricity by way of merging two or more grid systems.
Existing photovoltaic combining inverter control method can not be eliminated steady-state error, and precision and stability is lower, grid-connected current control poor effect.
Summary of the invention
The embodiment of the invention provides a kind of photovoltaic combining inverter composite control method, to solve the problem of grid-connected current control poor effect in the prior art.
The technical scheme that the embodiment of the invention adopts is as follows:
A kind of photovoltaic combining inverter composite control method comprises: input current is carried out the 3s/2r conversion, set up the combining inverter model under the d-q coordinate system; Adopt composite controller that output current is controlled, eliminate the even-order harmonic component disturbance in the output current, described composite controller comprises PI controller and repetitive controller in parallel.
The embodiment of the invention adopts carries out the 3s/2r conversion to input current, the composite controller that utilization is comprised of PI controller and the repetitive controller of parallel connection is eliminated the technical scheme of the even-order harmonic component disturbance in the output current, improved the dynamic response of system, precision and stability is higher, can better control the harmonic component disturbance, eliminate steady-state error, have better grid-connected current control effect.
Description of drawings
Fig. 1 is the schematic diagram of voltage oriented vector control system;
Fig. 2 is the principle assumption diagram of the composite controller of embodiment of the invention employing;
Fig. 3 adopts the embodiment of the invention to adopt the structure principle chart of compound control;
Fig. 4 is the flow chart of the photovoltaic combining inverter composite control method that provides of the embodiment of the invention.
Embodiment
The embodiment of the invention provides a kind of photovoltaic combining inverter composite control method, can solve existing control method and can not eliminate steady-state error, the technical problem that precision and stability is not high.Below be elaborated.
Embodiment one,
The photovoltaic combining inverter composite control method that the embodiment of the invention provides is based on voltage oriented vector control, is the improvement on existing voltage oriented vector control method basis.Embodiment of the invention method adopts Direct Current Control and carries out orientation with the line voltage vector, and the control by to amplitude and the phase place of inverter output current realizes that combining inverter is to the control of active power and reactive power.The theory structure of voltage oriented vector control system as shown in Figure 1.
The present embodiment method is at first carried out the 3s/2r coordinate transform to the input current from photovoltaic grid-connected power generation device, sets up the combining inverter model under the d-q coordinate system.After the coordinate transform, in the d-q coordinate system, the three phase sine first-harmonic is presented as constant DC quantity.For these characteristics, the control program that present embodiment is selected to adopt PI control and repeated to control combination, PI controller and repetitive controller is in parallel, consist of Embedded composite controller.The PI controller can the instruction of astatic tracking direct current, and when the disturbance of combining inverter was the first-harmonic disturbance, the PI controller can suppress the output voltage that this disturbance causes fast to be changed; For the harmonic component disturbance, the PI controller also has certain control action, but can not eliminate steady-state error.Present embodiment adopts the composite controller that is made of PI controller and repetitive controller parallel connection to eliminate steady-state error.
The content of high order harmonic component is very low in the output current behind the LCL filter, and what need inhibition mainly is low-order harmonic.Analyzing the reason that low-order harmonic occurs mainly contains: Dead Time, inverter inside are asymmetric, grid side voltage distortion etc., and these disturbing signals have common characteristics: be periodic disturbance, disturbing signal periodically occurs.
No matter low-order harmonic in the three-phase grid-connected inverter is the low-order harmonic that dead time effect produces, or the harmonic wave that comprises of line voltage, is mainly odd harmonic.Adopt symmetrical component method, unsymmetrical current can resolve into positive sequence component, negative sequence component and zero-sequence component.Take positive sequence component corresponding to unsymmetrical current as example:
After the 3s/2r conversion, in rotation d-q coordinate system, the positive sequence variable can be expressed as respectively:
Same carries out coordinate transform to negative phase-sequence variable and zero sequence variable, can obtain drawing a conclusion:
After coordinate transform, positive sequence component reduces an order, and standard positive sequence first-harmonic amount is DC quantity in the d-q coordinate system; The negative sequence component order that then raises, negative phase-sequence first-harmonic amount is 2 subharmonic; The zero sequence variable in rotating coordinate system for not existing.To sum up, through coordinate transform, the disturbance of low-order harmonic component is even-order harmonic.
Therefore, the embodiment of the invention adopts composite control method based on the filtering even-order harmonic with the harmonic carcellation disturbance.Similar with integral element, also be a kind of cumulative effect to error based on the composite controller of filtering even-order harmonic, as long as the output order error is non-vanishing, composite controller is just constantly cumulative, the output controlled quentity controlled variable increased gradually by the cycle.In the present embodiment, this composite controller is placed the forward path of feedback control system, and with the primitive period as the accumulative total cycle, then can Fundamental wave suppression disturbance or the disturbance of frequency multiplication subharmonic.
The composite control method of present embodiment is pointed out in the internal model principle take internal model principle as the basis: under the system stability state accurately the precondition of track reference input signal be that closed-loop control system is stablized and included an input signal retainer.When input signal e repeated, internal mold carried out Cycle by Cycle to this error signal and adds up, until system's output tracking error is 0.According to Euler's formula, when
The time,
Be infinity, illustrate that internal mold can eliminate any subharmonic.If this internal model structure is incorporated in the feedback control system, so just can follows the tracks of any given signal and eliminate disturbance.But general internal mode controller is difficult to stablize, and the theory structure of the composite controller after the embodiment of the invention compensation as shown in Figure 2.
In design composite controller internal mold, key content is exactly the N in the cycle delay.In actual applications, this inner membrance needs N memory space storage data, and the memory space of the larger needs of N is larger.From the angle of steady-state error convergence, according to the steady-state error formula "
", N can affect the rate of convergence of error, and on the one hand N crosses the slow down rate of convergence of error of conference, on the other hand, can increase the size of transient tracking error.Thereby, should not select large N during actual design.In the conventional design, N generally is chosen for the ratio of sample frequency and fundamental frequency.For the ease of difference, hereinafter the N in the conventional design is designated as N0.
In the present embodiment, in order to improve grid-connected current control effect, the ratio that the N in the cycle delay is defined as sample frequency and fundamental frequency is divided by 2, and is more half as large than N0 in the conventional design.Below in conjunction with the structural principle of compound control shown in Figure 3, to the explanation of deriving of the control effect of composite controller in the present embodiment:
It is M (s) that the closed loop of the internal mode controller that composite controller comprises passes letter,
The control object of composite controller is
, wherein,
Be inverter model, then,
The closed loop of system passes letter:
Order
, by Euler's publicity as can be known:
, then,
The closed loop of system passes letter
As seen, when
The time, have
, that is, closed-loop system is at the error free track reference electric current of electrical network power frequency and integer multiple frequency place thereof.When getting N=N0/2, former formula becomes
, namely only to the error free tracking of even reference signal.This moment, N was kept to half of original N0, was conducive to reduce steady-state error, and did not change controller to the tracking accuracy of instruction.
To sum up, the photovoltaic combining inverter composite control method of the embodiment of the invention as shown in Figure 4, comprising:
101, input current is carried out the 3s/2r conversion, set up the combining inverter model under the d-q coordinate system;
102, adopt composite controller that output current is controlled, eliminate the even-order harmonic component disturbance in the output current, described composite controller comprises PI controller and repetitive controller in parallel.
The present embodiment method adopts the complex control algorithm based on the filtering even-order harmonic, but Effective Raise system accuracy and stability improve or do not affect at least the dynamic response of system.
In the preferred embodiment, when the Internal Model Control Algorithm of design composite controller, N in the cycle delay is kept to N0/2, make composite controller only to even-order harmonic preferably attenuation be arranged, only to the error free tracking of even reference signal, be conducive to reduce steady-state error, and do not change controller to the tracking accuracy of instruction.
One of ordinary skill in the art will appreciate that all or part of step in the whole bag of tricks of above-described embodiment can finish by hardware, also can finish by the relevant hardware of program command, this program can be stored in the computer-readable recording medium, and storage medium can comprise: read-only memory, random-access memory, disk or CD etc.
More than photovoltaic combining inverter composite control method that the embodiment of the invention is provided be described in detail, but the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof, should not be construed as limitation of the present invention.Those skilled in the art are in the technical scope that the present invention discloses, and the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.
Claims (3)
1. a photovoltaic combining inverter composite control method is characterized in that, comprising:
Input current is carried out the 3s/2r conversion, set up the combining inverter model under the d-q coordinate system;
Adopt composite controller that output current is controlled, eliminate the even-order harmonic component disturbance in the output current, described composite controller comprises PI controller and repetitive controller in parallel.
2. method according to claim 1 is characterized in that:
Described composite controller is connected in the forward path of feedback control system, take the primitive period as accumulative total the cycle.
3. method according to claim 1 is characterized in that:
In the Internal Model Control Algorithm that described composite controller adopts, the N in the cycle delay equals the ratio of sample frequency and fundamental frequency again divided by 2.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103683874A (en) * | 2013-11-06 | 2014-03-26 | 天津瑞能电气有限公司 | Double-feed current transformer control method based on repeated control |
| CN104410075A (en) * | 2014-12-22 | 2015-03-11 | 深圳市英威腾电气股份有限公司 | Harmonic current lead correction method and application equipment thereof |
| CN105610311A (en) * | 2016-01-21 | 2016-05-25 | 北京京仪绿能电力系统工程有限公司 | Method and device for harmonic suppression of photovoltaic inverter |
| CN105870972A (en) * | 2016-06-16 | 2016-08-17 | 扬州华鼎电器有限公司 | Intelligent control system of photovoltaic microgrid PWM (pulse-width modulation) inverter |
| CN105958527A (en) * | 2016-05-03 | 2016-09-21 | 长沙理工大学 | Photovoltaic grid connected inverter multiparameter hysteresis current composite control method |
| CN107919789A (en) * | 2017-11-21 | 2018-04-17 | 西安许继电力电子技术有限公司 | A kind of grid-connected converter current ratio integration Repetitive controller improved method |
| CN112020807A (en) * | 2018-05-01 | 2020-12-01 | 三菱电机株式会社 | Power conversion device |
| CN112165263A (en) * | 2020-09-21 | 2021-01-01 | 哈尔滨工程大学 | Current harmonic suppression method for three-phase VIENNA rectifier |
| CN113009404A (en) * | 2021-01-26 | 2021-06-22 | 江阴长仪集团有限公司 | Method for calibrating direct-current even harmonic error and electric energy meter |
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Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103683874A (en) * | 2013-11-06 | 2014-03-26 | 天津瑞能电气有限公司 | Double-feed current transformer control method based on repeated control |
| CN104410075A (en) * | 2014-12-22 | 2015-03-11 | 深圳市英威腾电气股份有限公司 | Harmonic current lead correction method and application equipment thereof |
| CN105610311A (en) * | 2016-01-21 | 2016-05-25 | 北京京仪绿能电力系统工程有限公司 | Method and device for harmonic suppression of photovoltaic inverter |
| CN105958527B (en) * | 2016-05-03 | 2018-11-27 | 长沙理工大学 | A kind of multi-parameter hysteresis current composite control method of photovoltaic combining inverter |
| CN105958527A (en) * | 2016-05-03 | 2016-09-21 | 长沙理工大学 | Photovoltaic grid connected inverter multiparameter hysteresis current composite control method |
| CN105870972B (en) * | 2016-06-16 | 2018-10-16 | 扬州华鼎电器有限公司 | A kind of intelligence control system of photovoltaic microgrid PWM inverter |
| CN105870972A (en) * | 2016-06-16 | 2016-08-17 | 扬州华鼎电器有限公司 | Intelligent control system of photovoltaic microgrid PWM (pulse-width modulation) inverter |
| CN107919789A (en) * | 2017-11-21 | 2018-04-17 | 西安许继电力电子技术有限公司 | A kind of grid-connected converter current ratio integration Repetitive controller improved method |
| CN107919789B (en) * | 2017-11-21 | 2020-02-07 | 西安许继电力电子技术有限公司 | Current proportional-integral repetitive control improvement method for grid-connected converter |
| CN112020807A (en) * | 2018-05-01 | 2020-12-01 | 三菱电机株式会社 | Power conversion device |
| CN112165263A (en) * | 2020-09-21 | 2021-01-01 | 哈尔滨工程大学 | Current harmonic suppression method for three-phase VIENNA rectifier |
| CN112165263B (en) * | 2020-09-21 | 2022-04-12 | 哈尔滨工程大学 | Current harmonic suppression method for three-phase VIENNA rectifier |
| CN113009404A (en) * | 2021-01-26 | 2021-06-22 | 江阴长仪集团有限公司 | Method for calibrating direct-current even harmonic error and electric energy meter |
| CN113009404B (en) * | 2021-01-26 | 2023-08-11 | 江阴长仪集团有限公司 | DC even harmonic error calibration method and electric energy meter |
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Application publication date: 20130327 |