CN108493937B - Method, device and control system for restraining grid-connected inverter power grid background harmonic - Google Patents

Method, device and control system for restraining grid-connected inverter power grid background harmonic Download PDF

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CN108493937B
CN108493937B CN201810201272.6A CN201810201272A CN108493937B CN 108493937 B CN108493937 B CN 108493937B CN 201810201272 A CN201810201272 A CN 201810201272A CN 108493937 B CN108493937 B CN 108493937B
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axis
grid
voltage
connected point
point voltage
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CN108493937A (en
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吴轩钦
王凯
董瑞勇
戴华夏
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Shenzhen Invt Electric Co Ltd
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Shenzhen Invt Electric 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
    • 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
    • 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

Abstract

The invention discloses a method, a device and a control system for inhibiting grid-connected inverter power grid background harmonic, which are applied to a grid-connected inverter control system, wherein values of grid-connected point voltage after phase compensation of d-axis, q-axis 6-order and 12-order harmonic components are obtained by a grid-connected point voltage sampling value; then obtaining the regulated values of d and q axes of the inverter voltage according to the voltage sampling value of the grid-connected point, the current sampling value of the inverter side and the voltage phase of the grid-connected point; obtaining inverter pulse width modulation signals through the voltage phase of the grid-connected point, the sampling value of the voltage of the direct current bus, the phase-compensated values of 6-order and 12-order harmonic components of the voltage d axis and the q axis of the grid-connected point, and the adjustment values of the voltage d axis and the q axis of the inverter; and finally, controlling the operation of the motor according to the inverter pulse width modulation signal, and inhibiting grid-connected inverter power grid background harmonic waves. The invention can effectively inhibit 5, 7, 11 and 13 subharmonics which account for main components in the background harmonic of the power grid, improve the current quality of the power grid side and enhance the stability of the system.

Description

Method, device and control system for restraining grid-connected inverter power grid background harmonic
Technical Field
The invention relates to the technical field of grid-connected inverter control, in particular to a method, a device and a control system for inhibiting grid-connected inverter power grid background harmonic waves.
Background
A voltage type grid-connected inverter based on Pulse Width Modulation (PWM) has adjustable power factor, and can realize bidirectional flow of energy while reducing pollution to a power grid. As a bridge between a power generation (utilization) system and a power grid, the power generation (utilization) system is widely applied to the fields of alternating current transmission, new energy power generation, active filters, uninterruptible power supplies and the like.
The control strategy of the existing grid-connected inverter generally assumes that a power grid is an ideal sinusoidal voltage, and a power grid voltage directional vector control mode is adopted to obtain good input and output characteristics. However, the actual power grid background harmonic is usually caused by various rectification loads, mainly including 5, 7, 11, 13, …, 6k +/-1 subharmonics, so that the power grid shows the non-ideal characteristic of harmonic distortion. However, the power grid background harmonic wave can generate harmonic current at the grid-connected point of the system, and the harmonic current interacts with the power grid impedance, which may result in power grid harmonic amplification, seriously affect the quality of the grid-connected current, and even cause instability of the system, and cause damage to power generation and electric equipment.
In the prior art, a grid-connected inverter mainly has two control strategies, namely grid voltage proportion feedforward control and proportion resonance control, from the perspective of active suppression in order to suppress the influence of grid background harmonics, wherein the grid voltage proportion feedforward control strategy can effectively increase the output impedance of a system and reduce the influence of the grid background harmonics on grid-connected current, but under the condition of weak grid, the amplitude stability margin and the phase stability margin of the system are reduced by the coupling between the grid voltage proportion feedforward control and the current control; the proportional resonance control strategy is to inhibit the influence of the power grid background harmonic on grid-connected current by increasing the gain at the power grid background harmonic, but when the power grid background harmonic frequency is higher, the proportional resonance controller can reduce the phase angle margin of the system, thereby causing the instability problem. However, in an actual digital control system, the sampling and calculation delay further reduces the stability margin of the system, so that the two active suppression methods cannot completely eliminate the influence of the background harmonic waves of the power grid, and even may cause the system to be incapable of running stably, thereby affecting the quality of grid-connected current.
Disclosure of Invention
The invention aims to provide a method, a device and a control system for inhibiting grid-connected inverter power grid background harmonic waves, and aims to solve the problems that the influence of the power grid background harmonic waves cannot be completely eliminated by an active inhibition method adopted in the prior art, and even the grid-connected current quality is influenced because the system cannot stably operate.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for restraining grid-connected inverter power grid background harmonic waves is applied to a grid-connected inverter control system, and the grid-connected inverter control system comprises the following steps: a pre-filter phase-locked loop, a Butterworth bandpass filter, a delay compensator, a current rotary converter, a DC bus voltage regulator, a d-axis current regulator, a q-axis current regulator, a desired voltage synthesizer, and a voltage space vector regulator, the method comprising:
acquiring a current sampling value of an inverter side, a grid connection point voltage sampling value and a direct current bus voltage sampling value;
based on the pre-filtering phase-locked loop, the Butterworth band-pass filter and the delay compensator, obtaining values of phase compensation of harmonic components of the grid-connected point voltage d axis 6 times and 12 times and harmonic components of the grid-connected point voltage q axis 6 times and 12 times from the grid-connected point voltage sampling value;
Obtaining an inverter voltage d-axis regulation value and an inverter voltage q-axis regulation value from the grid-connected point voltage sampling value, the inverter side current sampling value and the grid-connected point voltage phase based on the current rotary converter, the direct current bus voltage regulator, the d-axis current regulator and the q-axis current regulator;
based on the expected voltage synthesizer and the voltage space vector modulation module, obtaining an inverter pulse width modulation signal by the grid-connected point voltage phase and the direct current bus voltage sampling value, the value of the grid-connected point voltage after 6-order and 12-order harmonic component phase compensation, the inverter voltage d-axis regulating value and the inverter voltage q-axis regulating value;
and controlling the operation of the motor according to the inverter pulse width modulation signal, and inhibiting the grid background harmonic of the grid-connected inverter.
Optionally, the step of obtaining, based on the pre-filter phase-locked loop, the butterworth band-pass filter, and the delay compensator, phase-compensated values of the grid-connected point voltage d-axis 6-order and 12-order harmonic components and the grid-connected point voltage q-axis 6-order and 12-order harmonic components from the grid-connected point voltage sampling value specifically includes:
Based on the pre-filter phase-locked loop, acquiring a d-axis harmonic component of the grid-connected point voltage and a q-axis harmonic component of the grid-connected point voltage by the grid-connected point voltage sampling value;
obtaining a grid-connected point voltage d-axis 6-order and 12-order harmonic components and a grid-connected point voltage q-axis 6-order and 12-order harmonic components from the grid-connected point voltage phase, the grid-connected point voltage d-axis harmonic component and the grid-connected point voltage q-axis harmonic component based on a Butterworth band-pass filter;
based on the time delay compensator, the phase-compensated values of the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order are obtained by the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order, and the phase-compensated values of the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order are obtained by the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order.
Optionally, the step of obtaining the harmonic component of the grid-connected point voltage d axis and the harmonic component of the grid-connected point voltage q axis from the grid-connected point voltage sampling value based on the pre-filter phase-locked loop specifically includes:
based on the pre-filter phase-locked loop, acquiring a grid-connected point voltage phase, a grid-connected point voltage d-axis component, a grid-connected point voltage q-axis component, a grid-connected point voltage d-axis fundamental wave component and a grid-connected point voltage q-axis fundamental wave component from the grid-connected point voltage sampling value;
And performing difference processing on the grid-connected point voltage d-axis component and the grid-connected point voltage d-axis fundamental wave component, and performing difference processing on the grid-connected point voltage q-axis component and the grid-connected point voltage q-axis fundamental wave component to respectively obtain the grid-connected point voltage d-axis harmonic component and the grid-connected point voltage q-axis harmonic component.
Optionally, the step of obtaining an inverter voltage d-axis adjustment value and an inverter voltage q-axis adjustment value from the grid-connected point voltage sampling value, the inverter side current sampling value, and the grid-connected point voltage phase based on the current rotating converter, the direct current bus voltage regulator, the d-axis current regulator, and the q-axis current regulator specifically includes:
based on the current rotation converter, obtaining an inverter side current d-axis component and an inverter side current q-axis component from the inverter side current sampling value and the grid connection point voltage phase;
performing difference processing on a direct current bus voltage expected value and the direct current bus voltage sampling value, and inputting the difference value into the direct current bus voltage regulator to obtain a d-axis current expected value and a q-axis current expected value;
performing difference processing on the d-axis current expected value and the d-axis component of the inverter side current, and inputting the d-axis current expected value and the d-axis component of the inverter side current into the d-axis current regulator to obtain an inverter voltage d-axis regulating value;
And performing difference processing on the q-axis current expected value and the q-axis component of the inverter side current, inputting the difference value into the q-axis current regulator, and obtaining an inverter voltage q-axis regulating value.
Optionally, the step of obtaining an inverter pulse width modulation signal from the grid-connected point voltage phase and the dc bus voltage sampling value, the value of the grid-connected point voltage after phase compensation of the harmonic components of the d-axis 6 times and 12 times, the value of the grid-connected point voltage after phase compensation of the harmonic components of the q-axis 6 times and 12 times, the inverter voltage d-axis adjustment value, and the inverter voltage q-axis adjustment value based on the expected voltage synthesizer and the voltage space vector modulation module specifically includes:
obtaining an inverter voltage d-axis expected value and an inverter voltage q-axis expected value by the value of the grid-connected point voltage d-axis 6-order and 12-order harmonic component after phase compensation, the value of the grid-connected point voltage q-axis 6-order and 12-order harmonic component after phase compensation, the grid-connected point voltage d-axis fundamental wave component, the grid-connected point voltage q-axis fundamental wave component, the inverter voltage d-axis regulating value and the inverter voltage q-axis regulating value based on the expected voltage synthesizer;
and obtaining an inverter pulse width modulation signal according to the expected value of the d axis of the inverter voltage, the expected value of the q axis of the inverter voltage, the voltage phase of the grid-connected point and the sampling value of the direct-current bus voltage based on the voltage space vector modulation module.
An apparatus for suppressing grid-connected inverter grid background harmonics, comprising:
the acquisition module is used for acquiring a current sampling value of the inverter side, a grid connection point voltage sampling value and a direct current bus voltage sampling value;
the first calculation module is used for obtaining values after phase compensation of harmonic components of a grid-connected point voltage d axis 6 times and 12 times and harmonic components of a grid-connected point voltage q axis 6 times and 12 times based on the pre-filtering phase-locked loop, the Butterworth band-pass filter and the delay compensator;
a second calculation module for obtaining an inverter voltage d-axis adjustment value and an inverter voltage q-axis adjustment value from the grid-connected point voltage sampling value, the inverter side current sampling value, and the grid-connected point voltage phase based on the current rotation converter, the direct current bus voltage regulator, the d-axis current regulator, and the q-axis current regulator;
a third calculating module, configured to obtain an inverter pulse width modulation signal according to the grid-connected point voltage phase and the dc bus voltage sampling value, the phase-compensated value of the harmonic component of the grid-connected point voltage d-axis 6 th and 12 th, the phase-compensated value of the harmonic component of the grid-connected point voltage q-axis 6 th and 12 th, the d-axis adjustment value of the inverter voltage, and the q-axis adjustment value of the inverter voltage based on the desired voltage synthesizer and the voltage space vector modulation module;
And the control module is used for controlling the operation of the motor according to the inverter pulse width modulation signal and inhibiting the grid-connected inverter power grid background harmonic wave.
Optionally, the first computing module includes:
the first calculation unit is used for obtaining a d-axis harmonic component of the grid-connected point voltage and a q-axis harmonic component of the grid-connected point voltage by the grid-connected point voltage sampling value based on the pre-filtering phase-locked loop;
a second calculating unit, configured to obtain, based on a butterworth bandpass filter, a grid-connected point voltage d-axis 6-order and 12-order harmonic components and a grid-connected point voltage q-axis 6-order and 12-order harmonic components from the grid-connected point voltage phase, the grid-connected point voltage d-axis harmonic component, and the grid-connected point voltage q-axis harmonic component;
and the third calculating unit is used for obtaining the values of the grid-connected point voltage d after 6-order and 12-order harmonic component phase compensation according to the grid-connected point voltage d-axis 6-order and 12-order harmonic components and obtaining the values of the grid-connected point voltage q-axis 6-order and 12-order harmonic component phase compensation according to the grid-connected point voltage q-axis 6-order and 12-order harmonic components based on the delay compensator.
Optionally, the first computing unit is specifically configured to:
based on the pre-filter phase-locked loop, acquiring a grid-connected point voltage phase, a grid-connected point voltage d-axis component, a grid-connected point voltage q-axis component, a grid-connected point voltage d-axis fundamental wave component and a grid-connected point voltage q-axis fundamental wave component from the grid-connected point voltage sampling value;
And performing difference processing on the grid-connected point voltage d-axis component and the grid-connected point voltage d-axis fundamental wave component, and performing difference processing on the grid-connected point voltage q-axis component and the grid-connected point voltage q-axis fundamental wave component to respectively obtain the grid-connected point voltage d-axis harmonic component and the grid-connected point voltage q-axis harmonic component.
Optionally, the second computing module includes:
a fourth calculation unit configured to obtain an inverter-side current d-axis component and an inverter-side current q-axis component from the inverter-side current sampling value and the grid-connected point voltage phase, based on the current rotation converter;
the first difference processing unit is used for carrying out difference processing on a direct-current bus voltage expected value and the direct-current bus voltage sampling value, and inputting the difference values into the direct-current bus voltage regulator to obtain a d-axis current expected value and a q-axis current expected value;
the second difference processing unit is used for carrying out difference processing on the d-axis current expected value and the d-axis component of the inverter side current, and inputting the difference processing into the d-axis current regulator to obtain an inverter voltage d-axis regulating value;
and the third difference processing unit is used for carrying out difference processing on the q-axis current expected value and the q-axis component of the inverter side current, inputting the difference processing into the q-axis current regulator and obtaining an inverter voltage q-axis regulating value.
A grid-tied inverter control system comprising: a pre-filter phase-locked loop, a Butterworth bandpass filter, a delay compensator, a current rotary transformer, a DC bus voltage regulator, a d-axis current regulator, a q-axis current regulator, a desired voltage synthesizer, and a voltage space vector regulator, wherein:
the pre-filter phase-locked loop, the current rotary converter and the direct current bus voltage regulator are respectively connected with a power grid through a sampling circuit, the Butterworth band-pass filter is connected with the pre-filter phase-locked loop, the delay compensator is connected with the Butterworth band-pass filter, the d-axis current regulator and the q-axis current regulator are respectively connected with the direct current bus voltage regulator and the current conversion converter, the expected voltage synthesizer is respectively connected with the d-axis current regulator, the q-axis current regulator and the delay compensator, and the voltage space vector regulator is connected with the expected voltage synthesizer;
the pre-filter phase-locked loop is used for acquiring a grid-connected point voltage sampling value, and acquiring a grid-connected point voltage phase, a rotation angular velocity, a grid-connected point voltage d-axis harmonic component and a grid-connected point voltage q-axis harmonic component;
The Butterworth band-pass filter is used for obtaining the harmonic components of the grid-connected point voltage d axis 6 times and 12 times and the harmonic components of the grid-connected point voltage q axis 6 times and 12 times through the grid-connected point voltage phase, the harmonic component of the grid-connected point voltage d axis and the harmonic component of the grid-connected point voltage q axis;
the delay compensator is used for obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage d axis 6 times and 12 times through the harmonic components of the grid-connected point voltage d axis 6 times and 12 times, and obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage q axis 6 times and 12 times through the harmonic components of the grid-connected point voltage q axis 6 times and 12 times;
the current rotating converter is used for acquiring a current sampling value of an inverter side and a voltage phase of the grid connection point to acquire a current d-axis component of the inverter side and a current q-axis component of the inverter side;
the direct current bus voltage regulator is used for acquiring a direct current bus voltage sampling value, performing difference processing on a direct current bus voltage expected value and the direct current bus voltage sampling value, and inputting the difference value into the direct current bus voltage regulator to acquire a d-axis current expected value and a q-axis current expected value;
the d-axis current regulator is used for performing difference processing on the d-axis current expected value and the d-axis component of the inverter side current and inputting the d-axis current expected value and the d-axis component of the inverter side current into the d-axis current regulator to obtain an inverter voltage d-axis regulating value;
The q-axis current regulator is used for carrying out difference processing on the q-axis current expected value and the q-axis component of the inverter side current, inputting the difference value into the q-axis current regulator and obtaining an inverter voltage q-axis regulating value;
the expected voltage synthesizer is used for obtaining an inverter voltage d-axis expected value and an inverter voltage q-axis expected value through the values of the grid-connected point voltage d-axis after 6-order and 12-order harmonic component phase compensation, the values of the grid-connected point voltage q-axis after 6-order and 12-order harmonic component phase compensation, the inverter voltage d-axis regulating value and the inverter voltage q-axis regulating value;
the voltage space vector regulator is used for obtaining an inverter pulse width modulation signal through the inverter voltage d-axis expected value, the inverter voltage q-axis expected value, the grid-connected point voltage phase and the direct current bus voltage sampling value.
According to the technical scheme, compared with the prior art, the invention discloses a method, a device and a control system for inhibiting grid-connected inverter power grid background harmonic waves, which are applied to a grid-connected inverter control system, wherein the method comprises the steps of obtaining an inverter side current sampling value, a grid-connected point voltage sampling value and a direct current bus voltage sampling value; obtaining the phase compensation values of the harmonic components of the grid-connected point voltage d axis 6 times and 12 times and the harmonic components of the grid-connected point voltage q axis 6 times and 12 times according to the grid-connected point voltage sampling value; then obtaining an inverter voltage d-axis regulating value and an inverter voltage q-axis regulating value according to the grid-connected point voltage sampling value, the inverter side current sampling value and the grid-connected point voltage phase; obtaining inverter pulse width modulation signals through a grid connection point voltage phase and a direct current bus voltage sampling value, a value of the grid connection point voltage after 6-order and 12-order harmonic component phase compensation of a d axis, a value of the grid connection point voltage after 6-order and 12-order harmonic component phase compensation of a q axis, an inverter voltage d axis adjusting value and an inverter voltage q axis adjusting value; and finally, controlling the operation of the motor according to the inverter pulse width modulation signal, and inhibiting grid-connected inverter power grid background harmonic waves. The invention can effectively inhibit 5, 7, 11 and 13 subharmonics which account for main components in the background harmonic wave of the power grid, can obtain good inhibition effect under the condition of weak power grid, improves the current quality of the power grid side, simultaneously can reduce the coupling degree between the voltage feedforward control and the current control, improves the amplitude stability margin and the phase of the system, and enhances the stability of the system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic control structure diagram of a method for suppressing grid-connected inverter grid background harmonics according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of a method for suppressing grid-connected inverter power grid background harmonics according to an embodiment of the present invention;
fig. 3 is a flowchart illustrating an implementation manner of step S200 in fig. 2 according to an embodiment of the present invention;
fig. 4 is a flowchart illustrating an implementation manner of step S201 in fig. 3 according to an embodiment of the present invention;
fig. 5 is a flowchart illustrating an implementation manner of step S300 in fig. 2 according to an embodiment of the present invention;
fig. 6 is a flowchart illustrating an implementation manner of step S400 in fig. 2 according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an apparatus for suppressing grid-connected inverter power grid background harmonics according to an embodiment of the present invention;
Fig. 8 is a schematic structural diagram of an implementation manner of the first computing module 702 in fig. 7 according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of an implementation manner of the second computing module 703 in fig. 7 according to an embodiment of the present invention;
fig. 10 is a schematic structural diagram of an implementation manner of the third computing module 704 in fig. 7 according to an embodiment of the present invention.
Detailed Description
In the invention, because the power grid background harmonic is usually caused by various rectification loads, the harmonic of 5, 7, 11, 13, … and 6k +/-1 times is taken as the main harmonic, relatively speaking, the high harmonic component in the power grid background harmonic is small, and is limited by the switching frequency and the control characteristic of the grid-connected inverter, in order to ensure the control effect and stability, the harmonic of 17, 19 times and above with higher frequency is ignored, and the aim of inhibiting the voltage background harmonic of 5, 7, 11 and 13 times is taken as the target. In addition, in order to reduce the computation amount of the control system, the invention adopts a rotating reference coordinate system oriented by the voltage of the grid-connected point to implement a control algorithm.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a control structure diagram of a method for suppressing grid-connected inverter grid background harmonics includes the following components: 1-a grid-connected inverter; 2-an output filter; 3, a power grid, wherein the power grid is equivalent to a three-phase alternating current voltage source and impedance series connection mode; 4-grid-connected inverter control system. u. ofpccAB、upccBCTo the grid-connected point voltage, iiA、iiBIs the inverter side current udcThe direct current bus voltage regulator, the d-axis current regulator and the q-axis current regulator are proportional-integral regulators.
As shown in fig. 1, the grid-connected inverter control system 4 includes: a pre-filter phase-locked loop 41, a Butterworth bandpass filter 42, a delay compensator 43, a current rotary transformer 44, a DC bus voltage regulator 45, a d-axis current regulator 46, a q-axis current regulator 47, a desired voltage synthesizer 48, and a voltage space vector regulator 49, the system comprises a pre-filter phase-locked loop 41, a current rotation converter 44, a direct current bus voltage regulator 45, a Butterworth band-pass filter 42, a delay compensator 43, a d-axis current regulator 46, a q-axis current regulator 47, a desired voltage synthesizer 48, a d-axis current regulator 46, a q-axis current regulator 47, a delay compensator 43 and a voltage space vector regulator 49, wherein the pre-filter phase-locked loop 41, the current rotation converter 44 and the direct current bus voltage regulator 45 are respectively connected with a power grid 3 through a sampling circuit;
Specifically, the pre-filter phase-locked loop 41 is configured to obtain a grid-connected point voltage sampling value, and obtain a grid-connected point voltage phase, a rotation angular velocity, a grid-connected point voltage d-axis harmonic component, and a grid-connected point voltage q-axis harmonic component; the Butterworth band-pass filter 42 is used for obtaining the harmonic components of the grid-connected point voltage d axis 6 th order and 12 th order and the harmonic components of the grid-connected point voltage q axis 6 th order and 12 th order through the grid-connected point voltage phase, the harmonic components of the grid-connected point voltage d axis and the harmonic components of the grid-connected point voltage q axis; the delay compensator 43 is configured to obtain phase-compensated values of the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order through the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order, and obtain phase-compensated values of the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order from the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order; the current rotation converter 44 is configured to obtain an inverter-side current sampling value and a grid-connected point voltage phase, and obtain an inverter-side current d-axis component and an inverter-side current q-axis component; the direct-current bus voltage regulator 45 is configured to obtain a direct-current bus voltage sampling value, perform difference processing on a direct-current bus voltage expected value and the direct-current bus voltage sampling value, and input the difference to the direct-current bus voltage regulator to obtain a d-axis current expected value and a q-axis current expected value; the d-axis current regulator 46 is used for performing difference processing on a d-axis current expected value and an inverter side current d-axis component, and inputting the d-axis current expected value and the inverter side current d-axis component into the d-axis current regulator to obtain an inverter voltage d-axis regulating value; the q-axis current regulator 47 is configured to perform difference processing on a q-axis current expected value and an inverter-side current q-axis component, and input the difference to the q-axis current regulator to obtain an inverter voltage q-axis regulated value; the expected voltage synthesizer 48 is used for obtaining an inverter voltage d-axis expected value and an inverter voltage q-axis expected value through a value of the grid-connected point voltage d-axis after 6-order and 12-order harmonic component phase compensation, a value of the grid-connected point voltage q-axis after 6-order and 12-order harmonic component phase compensation, a grid-connected point voltage d-axis fundamental wave component, a grid-connected point voltage q-axis fundamental wave component, an inverter voltage d-axis regulated value and an inverter voltage q-axis regulated value; the voltage space vector regulator 49 is used for obtaining an inverter pulse width modulation signal through an inverter voltage d-axis expected value, an inverter voltage q-axis expected value, a grid connection point voltage phase and a direct current bus voltage sampling value.
It should be noted that the prefilter in the prefilter pll 41 is in the form of a generalized second-order integrator, and the pll is a common software pll. The butterworth bandpass filter 42 is a digital second order butterworth bandpass filter. The current rotary transformer 44 is a three-phase stationary/two-phase rotary coordinate transformation. The power circuit and the hardware control circuit of the invention are the same as the existing grid-connected inverter, only the control algorithm is optimized, and the invention has good compatibility and practicability. Compared with the existing control, the method fully considers the adverse effect of a digital control system, extracts the power grid voltage background harmonic through a digital second-order Butterworth band-pass filter, and feeds forward an accurate power grid voltage background harmonic component by adopting a delay compensator.
The invention adopts a rotating reference coordinate system oriented by grid-connected point voltage to implement a control algorithm, so that the embodiment of the invention provides the following method and device for inhibiting grid-connected inverter power grid background harmonic waves.
Referring to fig. 2, an embodiment of the present invention provides a method for suppressing grid-connected inverter grid background harmonics, which is applied to a grid-connected inverter control system, where the grid-connected inverter control system includes: the suppression method comprises the following steps of:
S100, obtaining a current sampling value of an inverter side, a grid connection point voltage sampling value and a direct current bus voltage sampling value.
And S200, obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage d axis 6 times and 12 times and the harmonic components of the grid-connected point voltage q axis 6 times and 12 times by the grid-connected point voltage sampling value based on a pre-filtering phase-locked loop, a Butterworth band-pass filter and a delay compensator.
In some embodiments, as shown in fig. 3, one implementation manner of step S200 may specifically be:
s201, acquiring a grid-connected point voltage d-axis harmonic component and a grid-connected point voltage q-axis harmonic component from a grid-connected point voltage sampling value based on a pre-filtering phase-locked loop.
In some embodiments, as shown in fig. 4, one implementation manner of step S201 may specifically be:
s201a, acquiring a grid connection point voltage phase, a grid connection point voltage d-axis component, a grid connection point voltage q-axis component, a grid connection point voltage d-axis fundamental wave component and a grid connection point voltage q-axis fundamental wave component from a grid connection point voltage sampling value based on a pre-filter phase-locked loop;
s201b, carrying out difference processing on the grid-connected point voltage d-axis component and the grid-connected point voltage d-axis fundamental wave component, and carrying out difference processing on the grid-connected point voltage q-axis component and the grid-connected point voltage q-axis fundamental wave component to respectively obtain a grid-connected point voltage d-axis harmonic component and a grid-connected point voltage q-axis harmonic component.
S202, based on a Butterworth band-pass filter, obtaining 6-order and 12-order harmonic components of a grid-connected point voltage d axis and 6-order and 12-order harmonic components of the grid-connected point voltage q axis from the grid-connected point voltage phase, the grid-connected point voltage d axis harmonic component and the grid-connected point voltage q axis harmonic component;
and S203, based on the time delay compensator, obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order from the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order, and obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order from the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order.
S300, based on the current rotating converter, the direct current bus voltage regulator, the d-axis current regulator and the q-axis current regulator, obtaining an inverter voltage d-axis regulating value and an inverter voltage q-axis regulating value from a grid-connected point voltage sampling value, an inverter side current sampling value and a grid-connected point voltage phase.
In some embodiments, as shown in fig. 5, one implementation manner of step S300 may specifically be:
s301, based on a current rotation converter, obtaining an inverter side current d-axis component and an inverter side current q-axis component from an inverter side current sampling value and a grid connection point voltage phase;
s302, performing difference processing on the direct current bus voltage expected value and the direct current bus voltage sampling value, and inputting the difference to a direct current bus voltage regulator to obtain a d-axis current expected value and a q-axis current expected value;
S303, performing difference processing on the d-axis current expected value and the d-axis component of the inverter side current, and inputting the d-axis current expected value and the d-axis component of the inverter side current into a d-axis current regulator to obtain an inverter voltage d-axis regulating value;
and S304, performing difference processing on the q-axis current expected value and the q-axis component of the inverter side current, inputting the difference value into a q-axis current regulator, and obtaining an inverter voltage q-axis regulating value.
S400, based on the expected voltage synthesizer and the voltage space vector modulation module, inverter pulse width modulation signals are obtained through grid connection point voltage phase and direct current bus voltage sampling values, values of grid connection point voltage d-axis 6-order and 12-order harmonic component phase compensation, values of grid connection point voltage q-axis 6-order and 12-order harmonic component phase compensation, inverter voltage d-axis adjusting values and inverter voltage q-axis adjusting values.
In some embodiments, as shown in fig. 6, one implementation manner of step S400 may specifically be:
s401, based on an expected voltage synthesizer, obtaining an expected value of a d axis of an inverter voltage and an expected value of a q axis of the inverter voltage by a value of the voltage of a grid-connected point after 6-order and 12-order harmonic component phase compensation, a d axis fundamental wave component of the voltage of the grid-connected point, a q axis fundamental wave component of the voltage of the grid-connected point, a value of the voltage of the q axis after 6-order and 12-order harmonic component phase compensation, a d axis regulating value of the inverter voltage and a q axis regulating value of the inverter voltage;
S402, based on the voltage space vector modulation module, obtaining inverter pulse width modulation signals through inverter voltage d-axis expected values, inverter voltage q-axis expected values, grid-connected point voltage phases and direct current bus voltage sampling values.
And S500, controlling the operation of the motor according to the inverter pulse width modulation signal, and inhibiting grid background harmonics of the grid-connected inverter.
The invention discloses a method for restraining grid-connected inverter power grid background harmonic, which is applied to a grid-connected inverter control system and comprises the steps of obtaining an inverter side current sampling value, a grid-connected point voltage sampling value and a direct current bus voltage sampling value; obtaining the phase compensation values of the harmonic components of the grid-connected point voltage d axis 6 times and 12 times and the harmonic components of the grid-connected point voltage q axis 6 times and 12 times according to the grid-connected point voltage sampling value; then obtaining an inverter voltage d-axis regulating value and an inverter voltage q-axis regulating value according to the grid-connected point voltage sampling value, the inverter side current sampling value and the grid-connected point voltage phase; obtaining inverter pulse width modulation signals through a grid connection point voltage phase and a direct current bus voltage sampling value, a value of the grid connection point voltage after 6-order and 12-order harmonic component phase compensation of a d axis, a value of the grid connection point voltage after 6-order and 12-order harmonic component phase compensation of a q axis, an inverter voltage d axis adjusting value and an inverter voltage q axis adjusting value; and finally, controlling the operation of the motor according to the inverter pulse width modulation signal, and inhibiting grid-connected inverter power grid background harmonic waves. The invention can effectively inhibit 5, 7, 11 and 13 subharmonics which account for main components in the background harmonic wave of the power grid, can obtain good inhibition effect under the condition of weak power grid, improves the current quality of the power grid side, simultaneously can reduce the coupling degree between the voltage feedforward control and the current control, improves the amplitude stability margin and the phase of the system, and enhances the stability of the system.
With reference to fig. 1 and fig. 2 to fig. 6, the method for suppressing grid-connected inverter grid background harmonics may specifically be described as including the following steps:
1. detecting inverter side current iiA、iiBVoltage u of grid-connected pointpccAB、upccBCDc bus voltage udcAnd sent to the grid-connected inverter control system 4.
2. The voltage u of the grid-connected pointpccAB、upccBCFeeding into a second stage with a generalized senseThe integral pre-filtering phase-locked loop 41 obtains the grid-connected point voltage vector phase thetapllAngular velocity ω of rotationgThe d axis of the rotating coordinate system is defined to coincide with the grid-connected point voltage vector, namely the orientation angle is thetapllThe q axis leads the d axis by 90 degrees. And obtaining the d-axis component u of the voltage of the grid-connected point by the pre-filter phase-locked loop 41pccdQ-axis component upccqGrid-connected point voltage d-axis fundamental wave component upccd1Q-axis fundamental wave component upccq1。
3. Will convert the inverter side current iiA、iiBAngle of orientation thetapllThe fed current rotating converter 44 obtains an inverter side d-axis current iidQ-axis current i on inverter sideiq。
4. The voltage d-axis component u of the grid-connected pointpccdQ-axis component upccqRespectively connected with the fundamental wave component u of the grid-connected point voltage d axispccd1Q-axis fundamental wave component upccq1Performing difference processing to obtain a grid-connected point voltage d-axis harmonic component upccdhAnd q-axis harmonic component upccqhIn order to realize the purpose,
Figure BDA0001594557340000131
5. constructing a digital second-order Butterworth band-pass filter module with a specific center frequency as shown in the following formula,
Figure BDA0001594557340000132
Wherein z is a discrete domain operator; coefficient b0、b1、b2、a0、a1、a2The constraint conditions of sampling frequency, band-pass frequency, band-stop upper limit frequency, band-stop lower limit frequency, band-stop attenuation and the like of the band-pass filter can be directly obtained through auxiliary design software FDATOOL of the Matlab filter, so that the complicated parameter design process is simplified.
6. Since the 5 th, 7 th and 11 th, 13 th voltage background harmonics in ABC natural stationary coordinate system are respectively expressed as 6 th and 12 th harmonics in rotating coordinate systemThe combination formula (1) is to combine the harmonic component u of the grid-connected point voltage d axispccdhAnd q-axis harmonic component upccqhBy a center frequency of 6 omega as shown in equation (2)gA digital second-order Butterworth band-pass filter, namely a direct-connection point voltage d-axis 6-order harmonic component upccd6Q-axis 6 harmonic component upccq6The expression is:
Figure BDA0001594557340000141
wherein the coefficient b06、b16、b26、a06、a16、a26The parameters of the 6 th harmonic digital second-order Butterworth band-pass filter under a rotating coordinate system can be directly obtained by filter auxiliary design software.
Combining the d-axis harmonic component u of the dot voltagepccdhAnd q-axis harmonic component upccqhRespectively with the d-axis 6 harmonic component u of the grid-connected point voltage obtained by the formula (3)pccd6Q-axis 6 harmonic component upccq6Making a difference, and passing the difference result through a center frequency of 12 omega as shown in formula (2)gThe d-axis 12-order harmonic component u of the voltage of the grid-connected point can be obtained by a digital second-order Butterworth band-pass filter pccd12Q-axis 12 harmonic component upccq12The expression is:
Figure BDA0001594557340000142
wherein the coefficient b012、b112、b212、a012、a112、a212The parameters of the 12 th harmonic digital second-order Butterworth band-pass filter under a rotating coordinate system can be directly obtained by filter auxiliary design software.
7. Considering the adverse effect of the delay effect of a digital control system, the existing control method adopts proportional feedforward 6-time and 12-time grid-connected point voltage harmonics, which can not completely inhibit the power grid voltage background harmonics, even may cause the amplification of the current harmonic current on the grid side under the condition of low switching frequency, and reduce the control performance. Therefore, the 6 th and 12 th voltage background harmonics extracted by the digital second order Butterworth band-pass filter are respectively passed through the delay compensation module to eliminate the digital control delay effect. According to different sampling loading modes, the introduced delay time TdCan be expressed as:
Figure BDA0001594557340000143
wherein, TSFor the switching period, N is the sample loading mode coefficient.
The input of the delay compensation module is specific electrical quantity d and q axis components under a rotating coordinate system, and the components are uniformly expressed as x without loss of generalityd、xqCompensated output representation
Figure BDA0001594557340000144
Figure BDA0001594557340000145
Wherein, ω ishTo compensate for the angular frequency of rotation of the signal.
According to the formulas (5) and (6), 5, 7, 11 and 13-th power grid voltage background harmonics with phase compensation can be obtained, and d and q axis components of 6 th and 12 th harmonics in a rotating coordinate system
Figure BDA0001594557340000151
The expression is as follows:
Figure BDA0001594557340000152
Figure BDA0001594557340000153
8. the control system adopts a double closed-loop vector control strategy of a side current inner loop of a DC bus voltage outer loop inverter to expect a DC bus voltage udcrefIs in direct contact with actual samplingCurrent bus voltage udcThe difference value is sent to a direct current bus voltage proportional-integral regulator, and a d-axis current expected value i is outputdrefThe expression is:
Figure BDA0001594557340000154
wherein, Kpu、KiuThe direct current bus voltage proportion integral regulator proportional coefficient and integral coefficient are respectively.
d-axis current desired value idrefAnd the inverter side d-axis current iidThe difference value is sent to a d-axis current proportional-integral regulator to output a d-axis voltage regulating value u of the inverterdpiThe expression is:
Figure BDA0001594557340000155
desired value of q-axis current iqrefAnd the inverter side q-axis current iiqThe difference value is sent to a q-axis current proportional-integral regulator to output a q-axis voltage regulating value u of the inverterqpiThe expression is:
Figure BDA0001594557340000156
in the formulae (10), (11), Kpi、KiiThe proportional coefficient and the integral coefficient of the current proportional-integral regulator are respectively.
Wherein the q-axis current desired value iqrefGiven according to the desired power factor.
9. Synthesizing the d-axis voltage regulation value u of the inverter output by the d-axis current proportional-integral regulator according to the formula (12)dpiD-axis fundamental wave component u of grid-connected point voltagepccd1D-axis 6-time component of grid-connected point voltage with delay compensation
Figure BDA0001594557340000157
D-axis 12-order component with delay compensation of grid-connected point voltage
Figure BDA0001594557340000158
Carrying out synthesis;
adjusting the q-axis voltage u of the inverter by the q-axis current proportional-integral regulator as shown in equation (12)qpiAnd the grid-connected point voltage q-axis fundamental wave component upccq1Q-axis 6-time component of grid-connected point voltage with delay compensation
Figure BDA0001594557340000159
Q-axis 12-order component with delay compensation of grid-connected point voltage
Figure BDA00015945573400001510
The expected values u of the voltages of the d and q axes of the inverter are obtained through synthesisdref、uqrefThe expression is:
Figure BDA0001594557340000161
10. expected values u of d-axis and q-axis voltages of the inverter are obtaineddref、uqrefAnd the orientation angle theta is vector-controlled by the software phase-locked loop modulepllSampling DC bus voltage udcAnd sending the voltage to a voltage space vector pulse modulator to generate a PWM control signal to drive a power device.
The invention adopts a digital second-order Butterworth band-pass filter, can more accurately extract harmonic components of the voltage of the grid-connected point, and can assist filter design software to simplify parameter design. Meanwhile, the input quantity of the band-pass filter is obtained by subtracting the voltage of the grid-connected point and the extracted voltage of each subharmonic, and the extraction effect is better. In addition, the delay effect of digital control is considered, the suppression effect of the background harmonic of the power grid voltage is improved by setting different frequency harmonic compensation angles, and the stability of the system is enhanced.
The method provided by the invention can effectively inhibit 5, 7, 11 and 13 harmonics which account for main components in the background harmonics of the power grid, has better stability compared with the existing method, can obtain good inhibition effect under the condition of weak power grid, and improves the current quality of the power grid side. In addition, the method provided by the invention can reduce the coupling degree between the voltage feedforward control and the current control, improve the amplitude stability margin and the phase of the system and enhance the stability of the system.
The invention also discloses a corresponding device on the basis of the method.
The device for suppressing the grid-connected inverter grid background harmonic wave provided by the embodiment of the present invention is described below, and it should be noted that for the description of the device for suppressing the grid-connected inverter grid background harmonic wave, reference may be made to the method for suppressing the grid-connected inverter grid background harmonic wave provided above, and details are not repeated below.
As shown in fig. 7, the present invention discloses a device for suppressing grid-connected inverter grid background harmonics, which specifically comprises: an obtaining module 701, a first calculating module 702, a second calculating module 703, a third calculating module 704 and a control module 705, wherein:
the acquisition module 701 is used for acquiring a current sampling value of an inverter side, a grid connection point voltage sampling value and a direct current bus voltage sampling value; a first calculating module 702, configured to obtain, based on the pre-filter phase-locked loop 41, the butterworth band-pass filter 42, and the delay compensator 43, phase-compensated values of the harmonic components of the grid-connected point voltage d-axis 6 th and 12 th and the harmonic components of the grid-connected point voltage q-axis 6 th and 12 th from the grid-connected point voltage sampling value; a second calculation module 703, configured to obtain an inverter voltage d-axis adjustment value and an inverter voltage q-axis adjustment value from the grid-connected point voltage sampling value, the inverter-side current sampling value, and the grid-connected point voltage phase based on the current rotation converter 44, the dc bus voltage regulator 45, the d-axis current regulator 46, and the q-axis current regulator 47; a third calculating module 704, configured to obtain an inverter pulse width modulation signal from a grid-connected point voltage phase and a dc bus voltage sampling value, a value of the grid-connected point voltage d-axis after 6-order and 12-order harmonic component phase compensation, a value of the grid-connected point voltage q-axis after 6-order and 12-order harmonic component phase compensation, an inverter voltage d-axis adjustment value, and an inverter voltage q-axis adjustment value based on the expected voltage synthesizer 48 and the voltage space vector modulation module 49; and the control module 705 is used for controlling the operation of the motor according to the inverter pulse width modulation signal and suppressing grid background harmonics of the grid-connected inverter.
Specifically, as shown in fig. 8, one implementation manner of the first calculation module 702 is as follows:
the first calculation module 702 includes: a first calculation unit 801, a second calculation unit 802, and a third calculation unit 803, wherein:
a first calculating unit 801, configured to obtain a grid-connected point voltage d-axis harmonic component and a grid-connected point voltage q-axis harmonic component from a grid-connected point voltage sampling value based on the pre-filter phase-locked loop 41; a second calculating unit 802, configured to obtain, based on the butterworth bandpass filter 42, a grid-connected point voltage d-axis 6 th and 12 th harmonic components and a grid-connected point voltage q-axis 6 th and 12 th harmonic components from the grid-connected point voltage phase, the grid-connected point voltage d-axis harmonic component and the grid-connected point voltage q-axis harmonic component; and a third calculating unit 803, configured to obtain phase-compensated values of the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order from the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order, and obtain phase-compensated values of the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order from the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order, based on the delay compensator 43.
The first calculating unit 801 is specifically configured to:
based on the pre-filter phase-locked loop 41, acquiring a grid-connected point voltage phase, a grid-connected point voltage d-axis component, a grid-connected point voltage q-axis component, a grid-connected point voltage d-axis fundamental wave component and a grid-connected point voltage q-axis fundamental wave component from a grid-connected point voltage sampling value;
And performing difference processing on the grid-connected point voltage d-axis component and the grid-connected point voltage d-axis fundamental wave component, and performing difference processing on the grid-connected point voltage q-axis component and the grid-connected point voltage q-axis fundamental wave component to respectively obtain a grid-connected point voltage d-axis harmonic component and a grid-connected point voltage q-axis harmonic component.
Specifically, as shown in fig. 9, one implementation manner of the second calculating module 703 is as follows:
the second calculation module 703 includes: a fourth calculation unit 901, a first difference processing unit 902, a second difference processing unit 903, and a third difference processing unit 904, wherein:
a fourth calculation unit 901 for obtaining an inverter-side current d-axis component and an inverter-side current q-axis component from the inverter-side current sample value and the grid-connected point voltage phase on the basis of the current rotation converter 44; a first difference processing unit 902, configured to perform difference processing on a dc bus voltage expected value and a dc bus voltage sampling value, and input the difference to a dc bus voltage regulator to obtain a d-axis current expected value and a q-axis current expected value; a second difference processing unit 903, configured to perform difference processing on the d-axis current expected value and the d-axis component of the inverter-side current, and input the difference to the d-axis current regulator to obtain an inverter voltage d-axis regulated value; and a third difference processing unit 904, configured to perform difference processing on the q-axis current desired value and the inverter-side current q-axis component, input the difference to the q-axis current regulator, and obtain an inverter voltage q-axis regulated value.
Specifically, as shown in fig. 10, one implementation manner of the third computing module 704 is as follows:
the third calculation module 704 includes: a fifth calculating unit 1001 and a sixth calculating unit 1002, wherein:
a fifth calculating unit 1001, configured to obtain an inverter voltage d-axis expected value and an inverter voltage q-axis expected value from the phase-compensated value of the harmonic component of the grid-connected point voltage d-axis 6 th order and 12 th order, the phase-compensated value of the harmonic component of the grid-connected point voltage q-axis 6 th order and 12 th order, the d-axis fundamental wave component of the grid-connected point voltage, the q-axis fundamental wave component of the grid-connected point voltage, the inverter voltage d-axis regulated value, and the inverter voltage q-axis regulated value, based on the expected voltage synthesizer 48; a sixth calculating unit 1002, configured to obtain an inverter pulse width modulation signal from the inverter voltage d-axis expected value, the inverter voltage q-axis expected value, the grid-connected point voltage phase, and the dc bus voltage sampling value based on the voltage space vector modulation module 49.
The invention discloses a device for inhibiting grid-connected inverter power grid background harmonic waves, which is characterized in that an inverter side current sampling value, a grid-connected point voltage sampling value and a direct current bus voltage sampling value are obtained; obtaining the phase compensation values of the harmonic components of the grid-connected point voltage d axis 6 times and 12 times and the harmonic components of the grid-connected point voltage q axis 6 times and 12 times according to the grid-connected point voltage sampling value; then obtaining an inverter voltage d-axis regulating value and an inverter voltage q-axis regulating value according to the grid-connected point voltage sampling value, the inverter side current sampling value and the grid-connected point voltage phase; obtaining inverter pulse width modulation signals through a grid connection point voltage phase and a direct current bus voltage sampling value, a value of the grid connection point voltage after 6-order and 12-order harmonic component phase compensation of a d axis, a value of the grid connection point voltage after 6-order and 12-order harmonic component phase compensation of a q axis, an inverter voltage d axis adjusting value and an inverter voltage q axis adjusting value; and finally, controlling the operation of the motor according to the inverter pulse width modulation signal, and inhibiting grid-connected inverter power grid background harmonic waves. The invention can effectively inhibit 5, 7, 11 and 13 subharmonics which account for main components in the background harmonic wave of the power grid, can obtain good inhibition effect under the condition of weak power grid, improves the current quality of the power grid side, simultaneously can reduce the coupling degree between the voltage feedforward control and the current control, improves the amplitude stability margin and the phase of the system, and enhances the stability of the system.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in an article or device that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A method for restraining grid-connected inverter power grid background harmonic waves is characterized by being applied to a grid-connected inverter control system, and the grid-connected inverter control system comprises the following steps: a pre-filter phase-locked loop, a Butterworth bandpass filter, a delay compensator, a current rotary converter, a DC bus voltage regulator, a d-axis current regulator, a q-axis current regulator, a desired voltage synthesizer, and a voltage space vector regulator, the method comprising:
acquiring a current sampling value of an inverter side, a grid connection point voltage sampling value and a direct current bus voltage sampling value;
based on the pre-filtering phase-locked loop, the Butterworth band-pass filter and the delay compensator, obtaining values of phase compensation of harmonic components of the grid-connected point voltage d axis 6 times and 12 times and harmonic components of the grid-connected point voltage q axis 6 times and 12 times from the grid-connected point voltage sampling value;
obtaining an inverter voltage d-axis regulation value and an inverter voltage q-axis regulation value from the grid-connected point voltage sampling value, the inverter side current sampling value and the grid-connected point voltage phase based on the current rotary converter, the direct current bus voltage regulator, the d-axis current regulator and the q-axis current regulator;
Based on the expected voltage synthesizer and the voltage space vector modulation module, obtaining an inverter pulse width modulation signal by the grid-connected point voltage phase and the direct current bus voltage sampling value, the value of the grid-connected point voltage after 6-order and 12-order harmonic component phase compensation, the inverter voltage d-axis regulating value and the inverter voltage q-axis regulating value;
controlling the operation of a motor according to the inverter pulse width modulation signal, and inhibiting the grid background harmonic of the grid-connected inverter;
the step of obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage d axis 6 times and 12 times and the harmonic components of the grid-connected point voltage q axis 6 times and 12 times based on the pre-filtering phase-locked loop, the Butterworth band-pass filter and the delay compensator specifically comprises the following steps:
based on the pre-filter phase-locked loop, acquiring a d-axis harmonic component of the grid-connected point voltage and a q-axis harmonic component of the grid-connected point voltage by the grid-connected point voltage sampling value;
obtaining a grid-connected point voltage d-axis 6-order and 12-order harmonic components and a grid-connected point voltage q-axis 6-order and 12-order harmonic components from the grid-connected point voltage phase, the grid-connected point voltage d-axis harmonic component and the grid-connected point voltage q-axis harmonic component based on a Butterworth band-pass filter;
Based on the time delay compensator, the phase-compensated values of the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order are obtained by the harmonic components of the grid-connected point voltage d-axis 6 th order and 12 th order, and the phase-compensated values of the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order are obtained by the harmonic components of the grid-connected point voltage q-axis 6 th order and 12 th order.
2. The method according to claim 1, wherein the step of obtaining the d-axis harmonic component and the q-axis harmonic component of the grid-connected point voltage from the grid-connected point voltage sampling value based on the pre-filter phase-locked loop specifically comprises:
based on the pre-filter phase-locked loop, acquiring a grid-connected point voltage phase, a grid-connected point voltage d-axis component, a grid-connected point voltage q-axis component, a grid-connected point voltage d-axis fundamental wave component and a grid-connected point voltage q-axis fundamental wave component from the grid-connected point voltage sampling value;
and performing difference processing on the grid-connected point voltage d-axis component and the grid-connected point voltage d-axis fundamental wave component, and performing difference processing on the grid-connected point voltage q-axis component and the grid-connected point voltage q-axis fundamental wave component to respectively obtain the grid-connected point voltage d-axis harmonic component and the grid-connected point voltage q-axis harmonic component.
3. The method according to claim 2, wherein the step of obtaining an inverter voltage d-axis regulation value and an inverter voltage q-axis regulation value from the grid-connected point voltage sampling value, the inverter side current sampling value and the grid-connected point voltage phase based on the current rotating converter, the direct current bus voltage regulator, the d-axis current regulator and the q-axis current regulator is specifically:
based on the current rotation converter, obtaining an inverter side current d-axis component and an inverter side current q-axis component from the inverter side current sampling value and the grid connection point voltage phase;
performing difference processing on a direct current bus voltage expected value and the direct current bus voltage sampling value, and inputting the difference value into the direct current bus voltage regulator to obtain a d-axis current expected value and a q-axis current expected value;
performing difference processing on the d-axis current expected value and the d-axis component of the inverter side current, and inputting the d-axis current expected value and the d-axis component of the inverter side current into the d-axis current regulator to obtain an inverter voltage d-axis regulating value;
and performing difference processing on the q-axis current expected value and the q-axis component of the inverter side current, inputting the difference value into the q-axis current regulator, and obtaining an inverter voltage q-axis regulating value.
4. The method according to claim 2, wherein the step of obtaining an inverter pulse width modulation signal from the grid-connected point voltage phase and the dc bus voltage sampled value, the grid-connected point voltage d-axis 6 th and 12 th harmonic component phase compensated value, the grid-connected point voltage q-axis 6 th and 12 th harmonic component phase compensated value, the inverter voltage d-axis adjustment value, and the inverter voltage q-axis adjustment value based on the desired voltage synthesizer and the voltage space vector modulation module is specifically:
obtaining an inverter voltage d-axis expected value and an inverter voltage q-axis expected value by the value of the grid-connected point voltage d-axis 6-order and 12-order harmonic component after phase compensation, the value of the grid-connected point voltage q-axis 6-order and 12-order harmonic component after phase compensation, the grid-connected point voltage d-axis fundamental wave component, the grid-connected point voltage q-axis fundamental wave component, the inverter voltage d-axis regulating value and the inverter voltage q-axis regulating value based on the expected voltage synthesizer;
and obtaining an inverter pulse width modulation signal according to the expected value of the d axis of the inverter voltage, the expected value of the q axis of the inverter voltage, the voltage phase of the grid-connected point and the sampling value of the direct-current bus voltage based on the voltage space vector modulation module.
5. A device for suppressing grid-connected inverter power grid background harmonic waves is characterized by comprising:
the acquisition module is used for acquiring a current sampling value of the inverter side, a grid connection point voltage sampling value and a direct current bus voltage sampling value;
the first calculation module is used for obtaining values after phase compensation of harmonic components of a grid-connected point voltage d axis 6 times and 12 times and harmonic components of a grid-connected point voltage q axis 6 times and 12 times based on a pre-filtering phase-locked loop, a Butterworth band-pass filter and a delay compensator;
a second calculation module for obtaining an inverter voltage d-axis regulation value and an inverter voltage q-axis regulation value from the grid-connected point voltage sampling value, the inverter side current sampling value and the grid-connected point voltage phase based on the current rotation converter, the direct current bus voltage regulator, the d-axis current regulator and the q-axis current regulator;
a third calculating module, configured to obtain an inverter pulse width modulation signal from the grid-connected point voltage phase and the dc bus voltage sampling value, the phase-compensated value of the harmonic component of the grid-connected point voltage d-axis for 6 times and 12 times, the phase-compensated value of the harmonic component of the grid-connected point voltage q-axis for 6 times and 12 times, the d-axis adjustment value of the inverter voltage, and the q-axis adjustment value of the inverter voltage based on a desired voltage synthesizer and a voltage space vector modulation module;
The control module is used for controlling the operation of the motor according to the inverter pulse width modulation signal and inhibiting the grid background harmonic of the grid-connected inverter;
wherein the first computing module comprises:
the first calculation unit is used for obtaining a d-axis harmonic component of the grid-connected point voltage and a q-axis harmonic component of the grid-connected point voltage by the grid-connected point voltage sampling value based on the pre-filtering phase-locked loop;
a second calculating unit, configured to obtain, based on a butterworth bandpass filter, a grid-connected point voltage d-axis 6-order and 12-order harmonic components and a grid-connected point voltage q-axis 6-order and 12-order harmonic components from the grid-connected point voltage phase, the grid-connected point voltage d-axis harmonic component, and the grid-connected point voltage q-axis harmonic component;
and the third calculating unit is used for obtaining the values of the grid-connected point voltage d after 6-order and 12-order harmonic component phase compensation according to the grid-connected point voltage d-axis 6-order and 12-order harmonic components and obtaining the values of the grid-connected point voltage q-axis 6-order and 12-order harmonic component phase compensation according to the grid-connected point voltage q-axis 6-order and 12-order harmonic components based on the delay compensator.
6. The apparatus according to claim 5, wherein the first computing unit is specifically configured to:
Based on the pre-filter phase-locked loop, acquiring a grid-connected point voltage phase, a grid-connected point voltage d-axis component, a grid-connected point voltage q-axis component, a grid-connected point voltage d-axis fundamental wave component and a grid-connected point voltage q-axis fundamental wave component from the grid-connected point voltage sampling value;
and performing difference processing on the grid-connected point voltage d-axis component and the grid-connected point voltage d-axis fundamental wave component, and performing difference processing on the grid-connected point voltage q-axis component and the grid-connected point voltage q-axis fundamental wave component to respectively obtain the grid-connected point voltage d-axis harmonic component and the grid-connected point voltage q-axis harmonic component.
7. The apparatus of claim 6, wherein the second computing module comprises:
a fourth calculation unit configured to obtain an inverter-side current d-axis component and an inverter-side current q-axis component from the inverter-side current sampling value and the grid-connected point voltage phase, based on the current rotation converter;
the first difference processing unit is used for carrying out difference processing on a direct-current bus voltage expected value and the direct-current bus voltage sampling value, and inputting the difference values into the direct-current bus voltage regulator to obtain a d-axis current expected value and a q-axis current expected value;
the second difference processing unit is used for carrying out difference processing on the d-axis current expected value and the d-axis component of the inverter side current, and inputting the difference processing into the d-axis current regulator to obtain an inverter voltage d-axis regulating value;
And the third difference processing unit is used for carrying out difference processing on the q-axis current expected value and the q-axis component of the inverter side current, inputting the difference processing into the q-axis current regulator and obtaining an inverter voltage q-axis regulating value.
8. A grid-connected inverter control system, comprising: a pre-filter phase-locked loop, a Butterworth bandpass filter, a delay compensator, a current rotary transformer, a DC bus voltage regulator, a d-axis current regulator, a q-axis current regulator, a desired voltage synthesizer, and a voltage space vector regulator, wherein:
the pre-filter phase-locked loop, the current rotary converter and the direct current bus voltage regulator are respectively connected with a power grid through a sampling circuit, the Butterworth band-pass filter is connected with the pre-filter phase-locked loop, the delay compensator is connected with the Butterworth band-pass filter, the d-axis current regulator and the q-axis current regulator are respectively connected with the direct current bus voltage regulator and the current conversion converter, the expected voltage synthesizer is respectively connected with the d-axis current regulator, the q-axis current regulator and the delay compensator, and the voltage space vector regulator is connected with the expected voltage synthesizer;
The pre-filter phase-locked loop is used for acquiring a grid-connected point voltage sampling value, and acquiring a grid-connected point voltage phase, a rotation angular velocity, a grid-connected point voltage d-axis harmonic component and a grid-connected point voltage q-axis harmonic component;
the Butterworth band-pass filter is used for obtaining the harmonic components of the grid-connected point voltage d axis 6 times and 12 times and the harmonic components of the grid-connected point voltage q axis 6 times and 12 times through the grid-connected point voltage phase, the harmonic component of the grid-connected point voltage d axis and the harmonic component of the grid-connected point voltage q axis;
the delay compensator is used for obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage d axis 6 times and 12 times through the harmonic components of the grid-connected point voltage d axis 6 times and 12 times, and obtaining the phase-compensated values of the harmonic components of the grid-connected point voltage q axis 6 times and 12 times through the harmonic components of the grid-connected point voltage q axis 6 times and 12 times;
the current rotating converter is used for acquiring a current sampling value of an inverter side and a voltage phase of the grid connection point to acquire a current d-axis component of the inverter side and a current q-axis component of the inverter side;
the direct current bus voltage regulator is used for acquiring a direct current bus voltage sampling value, performing difference processing on a direct current bus voltage expected value and the direct current bus voltage sampling value, and inputting the difference value into the direct current bus voltage regulator to acquire a d-axis current expected value and a q-axis current expected value;
The d-axis current regulator is used for performing difference processing on the d-axis current expected value and the d-axis component of the inverter side current and inputting the d-axis current expected value and the d-axis component of the inverter side current into the d-axis current regulator to obtain an inverter voltage d-axis regulating value;
the q-axis current regulator is used for carrying out difference processing on the q-axis current expected value and the q-axis component of the inverter side current, inputting the difference value into the q-axis current regulator and obtaining an inverter voltage q-axis regulating value;
the expected voltage synthesizer is used for obtaining an inverter voltage d-axis expected value and an inverter voltage q-axis expected value through the values of the grid-connected point voltage d-axis after 6-order and 12-order harmonic component phase compensation, the values of the grid-connected point voltage q-axis after 6-order and 12-order harmonic component phase compensation, the inverter voltage d-axis regulating value and the inverter voltage q-axis regulating value;
the voltage space vector regulator is used for obtaining an inverter pulse width modulation signal through the inverter voltage d-axis expected value, the inverter voltage q-axis expected value, the grid-connected point voltage phase and the direct current bus voltage sampling value.
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