CN111952975A - Power grid zero-crossing compensation method - Google Patents

Power grid zero-crossing compensation method Download PDF

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CN111952975A
CN111952975A CN202010733850.8A CN202010733850A CN111952975A CN 111952975 A CN111952975 A CN 111952975A CN 202010733850 A CN202010733850 A CN 202010733850A CN 111952975 A CN111952975 A CN 111952975A
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voltage
power grid
modulation voltage
grid
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CN111952975B (en
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聂欢
高钢
张凯涛
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East Group Co Ltd
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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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/06—Circuits specially adapted for rendering non-conductive gas discharge tubes or equivalent semiconductor devices, e.g. thyratrons, thyristors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics

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  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The invention relates to the technical field of rectifier converters and discloses a zero-crossing compensation method for a power grid. According to the method, voltage judgment of a zero crossing point region of the three-phase power grid is added on the basis that the traditional voltage outer ring controls bus voltage and the current inner ring controls inductive current. And judging whether the three-phase power grid crosses zero or not by collecting the voltages of the three-phase power grid and respectively judging whether the voltages of the three-phase power grid are in a zero crossing point region or not. When any phase of power grid in the three-phase power grid is judged to be zero-crossing, recording a first modulation voltage of the phase of power grid, clamping the first modulation voltage to zero, and reversely compensating second modulation voltages and third modulation voltages of other non-zero-crossing two-phase power grids for the voltage value of the first modulation voltage recorded before zero setting. By compensating the zero crossing point of the three-phase power grid, the problem that the grid-side current lags behind the grid-side voltage due to the internal resistance of the boost inductor and the delay of an inductive current control signal in a hardware circuit can be solved, and the current quality is improved.

Description

Power grid zero-crossing compensation method
Technical Field
The invention relates to the technical field of rectifier converters, in particular to a zero-crossing compensation method for a power grid.
Background
The three-phase Vienna rectifier is widely applied to occasions such as communication power supplies, uninterruptible power supplies, wind power generation and the like as a three-level rectifier. Compared with the traditional two-level rectifier, the power density is higher, so that the volume can be reduced when the power-saving rectifier is applied to a product, and the product is lightened; in addition, the unique structure enables the stress borne by the switch tube to be half of the voltage of a direct-current side bus, so that the switch tube is more suitable for being used in high-power high-voltage output, the problem of direct connection of bridge arms is avoided, the problem of poor current quality caused by setting dead time is avoided, and the reliability of the switch tube is indirectly improved. In a conventional control method of a three-phase Vienna rectifier, no matter SPWM control or SVPWM control, the phenomenon of current distortion at a zero-crossing point of a power grid caused by voltage drop on an inductor is inevitable, so that the Total Harmonic Distortion (THDI) of the power grid current is improved, and the quality of the power grid current is influenced.
Disclosure of Invention
Based on this, it is necessary to provide a power grid zero-crossing compensation method for the problem that current distortion is formed at the power grid zero-crossing point and the current quality of the power grid is affected.
A power grid zero-crossing compensation method comprises the steps of sampling voltages of a three-phase power grid respectively, and judging whether the voltages of the three-phase power grid are in a zero-crossing point region or not; if the voltage of a certain phase of power grid in the three-phase power grid is in a zero crossing point region, judging that the phase of power grid is in a zero crossing point state; acquiring a first modulation voltage of the phase in a zero-crossing point state, and carrying out zero setting clamping processing on the first modulation voltage; and acquiring second modulation voltage and third modulation voltage of the other two phases in a non-zero-crossing state, and performing reverse compensation on the second modulation voltage and the third modulation voltage, wherein the compensation value is a voltage value before the first modulation voltage is set to zero.
According to the power grid zero-crossing compensation method, the voltage judgment of the zero-crossing point region of the three-phase power grid is added on the basis of the traditional voltage outer ring control bus voltage and current inner ring control inductive current, and whether the three-phase power grid crosses zero is judged by collecting the voltages of the three-phase power grid and judging whether the voltages of the three-phase power grid are in the zero-crossing point region respectively. When the zero crossing of any phase of the three-phase power grid is judged, recording a first modulation voltage of the phase and clamping the first modulation voltage to zero, wherein second modulation voltages and third modulation voltages of other non-zero-crossing two phases need to reversely compensate the voltage value of the first modulation voltage recorded before zero crossing. The power grid zero-crossing compensation method provided by the invention is used for compensating the zero-crossing point of the three-phase power grid, and can solve the problem that the grid-side current lags behind the grid-side voltage due to the internal resistance of the boost inductor and the delay of the inductive current control signal in a hardware circuit, thereby greatly improving the distortion problem of the grid-side current zero-crossing point, reducing the total harmonic distortion rate of the power grid current and improving the current quality.
In one embodiment, the first modulation voltage, the second modulation voltage, and the third modulation voltage of the three-phase power grid after zero-crossing compensation are respectively:
Figure BDA0002604476210000021
wherein RecDrvVoltA is the first modulation voltage after zero crossing compensation; RecDrvVoltB is the second modulation voltage after zero crossing compensation; RecDrvVoltC is the third modulation voltage after zero crossing compensation; RecDrvVoltA' is the first modulation voltage before zero crossing compensation; RecDrvVoltB' is the second modulation voltage before zero crossing compensation; RecDrvVoltC' is the third modulation voltage before zero crossing compensation.
In one embodiment, the voltage of the zero-crossing region ranges from-30V to 30V.
In one embodiment, when the grid zero crossing compensation method further includes performing reverse compensation on the second modulation voltage and the third modulation voltage, the compensation value is obtained by multiplying a voltage value before the first modulation voltage is set to zero by a weight factor.
In one embodiment, the first modulation voltage, the second modulation voltage and the third modulation voltage of the three-phase power grid after adding the weight factor and performing zero-crossing compensation are respectively:
Figure BDA0002604476210000031
wherein RecDrvVoltA is the first modulation voltage after zero crossing compensation; RecDrvVoltB is the second modulation voltage after zero crossing compensation; RecDrvVoltC is the third modulation voltage after zero crossing compensation; RecDrvVoltA' is the first modulation voltage before zero crossing compensation; RecDrvVoltB' is the second modulation voltage before zero crossing compensation; RecDrvVoltC' is the third modulation voltage before zero crossing compensation; p is a weighting factor.
In one embodiment, the value range of the weight factor is 0-1.
In one embodiment, the value of the weighting factor is selected according to the voltage of the power grid.
In one embodiment, the weighting factor takes 0 when the effective value of the grid voltage is less than 150V and takes 1 when the effective value of the grid voltage is 220V.
A readable storage medium, on which a computer program is stored, which is executed by a processor to perform the steps of the grid zero crossing compensation method according to any of the above embodiments.
A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the steps of the grid zero crossing compensation method according to any one of the above embodiments.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart illustrating a method of compensating for zero crossing in a power grid according to an embodiment of the present invention;
FIG. 2 is a control block diagram of a method for adding zero-crossing compensation to a power grid according to an embodiment of the present invention;
FIG. 3 is a comparison graph of current waveforms before and after the method of zero-crossing compensation of the power grid is added when the power grid is fully loaded according to one embodiment of the present invention;
fig. 4 is a comparison diagram of current waveforms before and after a method of adding zero-crossing compensation to a power grid during half load according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "left," "right," "upper," "lower," "front," "rear," "circumferential," and the like are based on the orientation or positional relationship shown in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The three-phase Vienna rectifier is widely applied to occasions such as communication power supplies, uninterruptible power supplies, wind power generation and the like as a three-level rectifier. Compared with the traditional two-level rectifier, the power density of the rectifier is higher, so that the product can be reduced in size in application, and the product is light in weight. In addition, the unique structure enables the bearing stress of the switch tube to be half of the direct-current side bus voltage, so the switch tube is more suitable for being used in high-power high-voltage output, the problem of bridge arm direct connection can be avoided, and the problem of poor current quality caused by the arrangement of dead time is avoided, so the reliability of the switch tube is indirectly improved.
In the conventional control method of the three-phase Vienna rectifier, no matter SPWM control or SVPWM control is adopted, the phenomenon of current distortion at the zero crossing point of a power grid caused by voltage drop on an inductor is inevitable. Therefore, the THDI (Total Harmonic Current Distortion) is increased, and the quality of the grid Current is affected. The traditional power grid current zero-crossing compensation method needs to utilize a calculation formula:
Figure BDA0002604476210000051
and calculating the phase difference between the grid side current and the three-phase modulation voltage when the power grid passes through zero. However, the calculation formula is complicated, and because the parameters of the magnetic device change under different powers, the influence on the parameters of the magnetic device along with the increase of the power is more obvious, so that the result calculated by using the calculation formula often has larger deviation, and the method can not achieve satisfactory effect when being applied to actual products.
The invention aims to directly judge the zero crossing point region of a three-phase power grid according to the voltage of the power grid, and change the voltage of an original modulation wave in the region, thereby indirectly improving the problem of distortion of the current on the grid side at the zero crossing point.
Fig. 1 is a flowchart of a method of a zero-crossing compensation method of a power grid according to an embodiment of the present invention, where the zero-crossing compensation method of the power grid includes the following steps S100 to S400.
S100: and respectively sampling the voltage of the three-phase power grid, and judging whether the voltage of the three-phase power grid is in a zero crossing point region.
S200: and if the voltage of a certain phase of power grid in the three-phase power grid is in a zero crossing point region, judging that the phase of power grid is in a zero crossing point state.
S300: and acquiring a first modulation voltage of the phase power grid in a zero-crossing point state, and carrying out zero setting clamping processing on the first modulation voltage.
S400: and acquiring second modulation voltage and third modulation voltage of the other two phases in a non-zero-crossing state, and performing reverse compensation on the second modulation voltage and the third modulation voltage, wherein the compensation value is a voltage value before the first modulation voltage is set to zero.
The power grid zero-crossing compensation method provided by the invention is based on the traditional voltage outer loop control bus voltage and current inner loop control inductive current and adds the voltage judgment of the three-phase power grid in the zero-crossing region. The voltage of the three-phase power grid is collected and whether the voltage of the three-phase power grid is in a zero crossing point region or not is judged respectively. And if the voltage of one phase of power grid is in the zero-crossing point region, judging that the phase of power grid is in a zero-crossing point state, clamping the modulation voltage of the phase of power grid to zero, and reversely compensating the voltage value of the first modulation voltage before zero-crossing modulation of the phase of power grid by using the second modulation voltage and the third modulation voltage of other two phases of power grids which are not subjected to zero-crossing.
For example, the three-phase grid includes an a-phase grid, a B-phase grid, and a C-phase grid, respectively. After the A-phase power grid, the B-phase power grid and the C-phase power grid are respectively sampled, the voltage of the A-phase power grid is judged to be in the zero crossing point region, and then the A-phase power grid is judged to be in the zero crossing point state. And acquiring the first modulation voltage of the A-phase power grid, and recording the voltage value of the first modulation voltage of the A-phase power grid before modulation. And enabling the first modulation voltage of the A-phase power grid to be set to zero, and simultaneously acquiring a second modulation voltage of the B-phase power grid and a third modulation voltage of the C-phase power grid. And performing reverse compensation on the second modulation voltage and the third modulation voltage, wherein the compensation value of the reverse compensation is the voltage value of the first modulation voltage of the A-phase power grid before modulation. Similarly, when the voltage of the B-phase power grid or the C-phase power grid is in the zero-crossing region, the same processing is performed as that performed when the voltage of the a-phase power grid crosses zero, which is not described herein again. The power grid zero-crossing compensation method provided by the invention is used for compensating the zero-crossing point of the three-phase power grid, and can solve the problem that the grid-side current lags behind the grid-side voltage due to the internal resistance of the boost inductor and the delay of the inductive current control signal in a hardware circuit, thereby greatly improving the distortion problem of the grid-side current zero-crossing point, reducing the total harmonic distortion rate of the power grid current and improving the current quality.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 1 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least a portion of the other steps or stages.
In one embodiment, the first modulation voltage, the second modulation voltage, and the third modulation voltage of the three-phase power grid after zero-crossing compensation are respectively:
Figure BDA0002604476210000071
wherein RecDrvVoltA is the first modulation voltage after zero crossing compensation; RecDrvVoltB is the second modulation voltage after zero crossing compensation; RecDrvVoltC is the third modulation voltage after zero crossing compensation; RecDrvVoltA' is the first modulation voltage before zero crossing compensation; RecDrvVoltB' is the second modulation voltage before zero crossing compensation; RecDrvVoltC' is the third modulation voltage before zero crossing compensation.
In this embodiment, the three-phase power grid includes an a-phase power grid, a B-phase power grid, and a C-phase power grid, respectively. And if the voltage of the A-phase power grid is judged to be in the zero crossing point region after the A-phase power grid, the B-phase power grid and the C-phase power grid are sampled, judging that the A-phase power grid is in a zero crossing point state. And acquiring a first modulation voltage of the phase-A power grid, and recording a voltage value RecDrvVoltA' of the first modulation voltage at the moment. Meanwhile, the second modulation voltage recdrvvultb 'at the time of the B-phase power grid and the third modulation voltage recdrvvultc' at the time of the C-phase power grid are obtained. And carrying out zero setting and clamping treatment on the first modulation voltage of the A-phase power grid, namely enabling RecDrvVoltA to be 0, wherein RecDrvVoltA is the first modulation voltage subjected to zero-crossing compensation. Meanwhile, reverse compensation is carried out on the second modulation voltage RecDrvVoltB ' and the third modulation voltage RecDrvVoltC ', and the compensation value of the reverse compensation is the voltage value RecDrvVoltA ' of the first modulation voltage of the phase-A power grid before modulation; that is, RecDrvVoltB ═ RecDrvVoltB '-RecDrvVoltA', RecDrvVoltC ═ RecDrvVoltC '-RecDrvVoltA', where RecDrvVoltB is the second modulation voltage after zero-crossing compensation and RecDrvVoltC is the third modulation voltage after zero-crossing compensation. When the voltage of the B-phase power grid or the C-phase power grid is in the zero-crossing region, the same processing as that for the zero-crossing of the a-phase power grid is performed, which is not described herein.
In one embodiment, the voltage of the zero-crossing region ranges from-30V to 30V. In this embodiment, the zero-crossing compensation method for the power grid is applied to an actual product, and after repeated test tests, it is found that when the voltage range of the zero-crossing point region is selected to be-30V, the normal control effect of the control loop is not affected by using the method. Moreover, the power grid zero-crossing compensation method is applied to products and is tested for multiple times under different powers, so that the effect of the power grid zero-crossing compensation method on current zero-crossing compensation is more obvious when the power level is higher, the total harmonic distortion rate of the power grid current can be effectively reduced, and the hidden danger caused by distortion when the current crosses zero is avoided. Repeated experimental tests also verify that the power grid zero-crossing compensation method is simple and convenient in implementation steps, obvious in action effect and high in application reliability.
Fig. 2 is a control block diagram of a power grid zero crossing compensation method according to an embodiment of the present invention, in which in one embodiment, the power grid zero crossing compensation method further includes a step of multiplying a voltage value before the first modulation voltage is set to zero by a weighting factor when the second modulation voltage and the third modulation voltage are compensated in opposite directions. When the power grid zero-crossing compensation method is applied to an actual product and repeated test tests are carried out, it is found that if the input three-phase power grid voltage is very unstable, the amplitude of the power grid voltage changes obviously or when the amplitude of the power grid voltage is smaller, if the same compensation value as that under the normal power grid condition is used, larger current impact can be generated at the wave-sending moment. This is because, under the same power, the smaller the effective value of the grid voltage is, the larger the fundamental amplitude of the current is, and at this time, the two phases in the non-zero-crossing state will generate a larger drive due to the compensation effect of the algorithm, thereby causing a large current surge. Therefore, in this embodiment, after the power grid zero-crossing compensation method provided by the present invention is optimized, a weight factor whose value is associated with the amplitude of the power grid voltage is added to the method. That is, when the second modulation voltage and the third modulation voltage are compensated in the reverse direction, the compensation value is adjusted to be a voltage value before the first modulation voltage is set to zero and multiplied by a weighting factor, so that when the amplitude of the grid voltage is small, the reverse compensation of the two-phase voltage in the non-zero-crossing state is too large, and a large current impact is caused. The stability and the adaptability of the power grid zero-crossing compensation method provided by the invention are further improved by introducing the weight factor.
In one embodiment, the first modulation voltage, the second modulation voltage and the third modulation voltage of the three-phase power grid after adding the weight factor and performing zero-crossing compensation are respectively:
Figure BDA0002604476210000091
wherein RecDrvVoltA is the first modulation voltage after zero crossing compensation; RecDrvVoltB is the second modulation voltage after zero crossing compensation; RecDrvVoltC is the third modulation voltage after zero crossing compensation; RecDrvVoltA' is the first modulation voltage before zero crossing compensation; RecDrvVoltB' is the second modulation voltage before zero crossing compensation; RecDrvVoltC' is the third modulation voltage before zero crossing compensation; p is a weighting factor.
Similarly, after the A-phase power grid is judged to be in the zero-crossing point state, a first modulation voltage of the A-phase power grid is obtained, and the voltage value RecDrvVoltA' of the first modulation voltage at the moment is recorded. Meanwhile, the second modulation voltage recdrvvultb 'at the time of the B-phase power grid and the third modulation voltage recdrvvultc' at the time of the C-phase power grid are obtained. And carrying out zero setting and clamping treatment on the first modulation voltage of the A-phase power grid, namely enabling RecDrvVoltA to be 0, wherein RecDrvVoltA is the first modulation voltage subjected to zero-crossing compensation. Meanwhile, the second modulation voltage recdrvvultb ' and the third modulation voltage recdrvvultc ' are reversely compensated, and in this embodiment, a compensation value of the reverse compensation is a voltage value recdrvvulta ' of the first modulation voltage of the a-phase power grid before modulation multiplied by a weighting factor p; that is, RecDrvVoltB ═ RecDrvVoltB '-RecDrvVoltA'. p, and RecDrvVoltC ═ RecDrvVoltC '-RecDrvVoltA'. p, where RecDrvVoltB is the second modulation voltage adjusted by adding the weight factor and zero-crossing compensated, and RecDrvVoltC is the third modulation voltage adjusted by adding the weight factor and zero-crossing compensated. When the voltage of the B-phase power grid or the C-phase power grid is in the zero-crossing region, the same processing as that for the zero-crossing of the a-phase power grid is performed, which is not described herein.
In one embodiment, the value range of the weight factor is 0-1. The zero-crossing compensation method for the power grid provided by the invention adds zero-crossing region compensation for the power grid voltage in normal double-loop control. Two key points of the method are respectively as follows: judging a zero-crossing region; and selecting the value of the weighting factor p to regulate the modulation voltage for the second time. The power grid zero-crossing compensation method is applied to an actual product, and repeated test tests show that the value range of the weight factor is selected to be 0-1, and a large impact current can be well prevented from occurring in a circuit when the weight factor is used for carrying out secondary adjustment on zero-crossing compensation.
In one embodiment, the value of the weighting factor is selected according to the voltage of the power grid. Under the same power, the smaller the effective value of the power grid voltage is, the larger the basic amplitude of the power grid current is, and the compensation effect of the method on the two phases in the non-zero-crossing state can generate a larger drive, so that a large current impact is caused. The weight factor is introduced to adjust the compensation effect of the two phases in the non-zero-crossing state, so that the specific value of the weight factor is related to the voltage value of the power grid. In this embodiment, the value of the weighting factor is in a positive correlation with the grid voltage value. That is, the smaller the voltage value of the power grid is, the smaller the value of the weight factor is; and when the voltage value of the power grid is larger, the value of the weight factor is also larger. When the voltage value of the power grid is small, a small weight factor is selected, the reverse compensation value of the two phases in the non-zero-crossing state is small, and therefore the driving value generated by the two-phase voltage in the non-zero-crossing state is small, and large impact current cannot be formed. When the voltage value of the power grid is large, the selected weight factor is also large, and when the effective value of the voltage of the power grid is large, the basic amplitude of the current is small, so that the situation that large impact current is caused by reverse compensation of two phases in a non-zero-crossing state is not needed to be worried about, and therefore the two phases in the non-zero-crossing state can be subjected to reverse compensation with large compensation values. The power grid zero-crossing compensation method provided by the invention is used for compensating the zero-crossing point of the three-phase power grid, and can solve the problem that the grid-side current lags behind the grid-side voltage due to the internal resistance of the boost inductor and the delay of the inductive current control signal in a hardware circuit, thereby greatly improving the distortion problem of the grid-side current zero-crossing point, reducing the total harmonic distortion rate of the power grid current and improving the current quality.
In one embodiment, the weighting factor takes 0 when the effective value of the grid voltage is less than 150V and takes 1 when the effective value of the grid voltage is 220V. In practical application, the specific value of p should be correspondingly tested and adjusted according to the practical product of application.
Fig. 3 is a comparison graph of current waveforms before and after the power grid zero-crossing compensation method is added during full load according to an embodiment of the present invention, and fig. 4 is a comparison graph of current waveforms before and after the power grid zero-crossing compensation method is added during half load according to an embodiment of the present invention. Fig. 3 (a) is a graph showing a comparison of current waveforms before the zero-crossing compensation method of the power grid is used when the power is fully loaded, and fig. 3 (b) is a graph showing a comparison of current waveforms after the zero-crossing compensation method of the power grid is used when the power is fully loaded; fig. 4 (a) is a graph showing a comparison of current waveforms before the zero-crossing compensation method of the power grid is used when the power is at half load, and fig. 4 (b) is a graph showing a comparison of current waveforms after the zero-crossing compensation method of the power grid is used when the power is at half load. By comparing the graphs (a) and (b) in fig. 3 with the graphs (a) and (b) in fig. 4, it can be found that the distortion condition of the power grid current at the zero-crossing position can be greatly optimized after the power grid zero-crossing compensation method provided by the invention is added under different power conditions, and meanwhile, the method has more obvious effect on current zero-crossing compensation along with the increase of the power level, so that the total harmonic distortion rate of the power grid current can be effectively reduced, and the current quality is improved.
The present invention also provides a readable storage medium, on which a computer program is stored, where the program is executed by a processor to perform the steps of the grid zero crossing compensation method according to any one of the above embodiments.
The invention further provides a computer device, which includes a memory, a processor and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the processor implements the steps of the grid zero-crossing compensation method in any one of the above embodiments.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A grid zero crossing compensation method is characterized by comprising the following steps:
respectively sampling the voltage of the three-phase power grid, and judging whether the voltage of the three-phase power grid is in a zero crossing point region;
if the voltage of a certain phase of power grid in the three-phase power grid is in a zero crossing point region, judging that the phase of power grid is in a zero crossing point state;
acquiring a first modulation voltage of the phase power grid in a zero crossing point state, and carrying out zero setting clamping processing on the first modulation voltage;
and acquiring a second modulation voltage and a third modulation voltage of the other two-phase voltage in a non-zero-crossing state, and performing reverse compensation on the second modulation voltage and the third modulation voltage, wherein the compensation value is a voltage value before the first modulation voltage is set to zero.
2. A grid zero-crossing compensation method according to claim 1, wherein the first modulation voltage, the second modulation voltage and the third modulation voltage of the three-phase grid after zero-crossing compensation are respectively:
Figure FDA0002604476200000011
wherein RecDrvVoltA is the first modulation voltage after zero crossing compensation; RecDrvVoltB is the second modulation voltage after zero crossing compensation; RecDrvVoltC is the third modulation voltage after zero crossing compensation; RecDrvVoltA' is the first modulation voltage before zero crossing compensation; RecDrvVoltB' is the second modulation voltage before zero crossing compensation; RecDrvVoltC' is the third modulation voltage before zero crossing compensation.
3. A grid zero crossing compensation method according to claim 2, wherein the voltage range of the zero crossing region is-30V.
4. A grid zero crossing compensation method according to claim 1, characterized in that the grid zero crossing compensation method further comprises:
and when the second modulation voltage and the third modulation voltage are subjected to reverse compensation, the compensation value is obtained by multiplying the voltage value of the first modulation voltage before the first modulation voltage is set to zero by a weight factor.
5. A power grid zero-crossing compensation method as claimed in claim 4, wherein the first modulation voltage, the second modulation voltage and the third modulation voltage of the three-phase power grid after adding the weighting factor and zero compensation are respectively:
Figure FDA0002604476200000021
wherein RecDrvVoltA is the first modulation voltage after zero crossing compensation; RecDrvVoltB is the second modulation voltage after zero crossing compensation; RecDrvVoltC is the third modulation voltage after zero crossing compensation; RecDrvVoltA' is the first modulation voltage before zero crossing compensation; RecDrvVoltB' is the second modulation voltage before zero crossing compensation; RecDrvVoltC' is the third modulation voltage before zero crossing compensation; p is a weighting factor.
6. A power grid zero-crossing compensation method as claimed in claim 5, wherein the weighting factor has a value range of 0-1.
7. A grid zero-crossing compensation method as claimed in claim 6, characterized in that the value of the weighting factor is selected according to the voltage of the grid.
8. A grid zero crossing compensation method according to claim 7, wherein the weighting factor takes 0 when the effective value of the grid voltage is less than 150V and takes 1 when the effective value of the grid voltage is 220V.
9. A readable storage medium having stored thereon a computer program, characterized in that the program is executed by a processor for performing the steps of the grid zero crossing compensation method as claimed in any one of claims 1 to 8.
10. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the grid zero crossing compensation method according to any one of claims 1 to 8 when executing the program.
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