CN115313494A - Inverter harmonic suppression method, controller and inverter - Google Patents

Inverter harmonic suppression method, controller and inverter Download PDF

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CN115313494A
CN115313494A CN202211070770.4A CN202211070770A CN115313494A CN 115313494 A CN115313494 A CN 115313494A CN 202211070770 A CN202211070770 A CN 202211070770A CN 115313494 A CN115313494 A CN 115313494A
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inverter
voltage
output
grid
calculating
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高明智
许佳雄
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Hangzhou Sllcpower Co ltd
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Hangzhou Sllcpower 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
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • 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
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • 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 provides an inverter harmonic suppression method, which comprises the following steps: step S100: according to the instantaneous output voltage V of the inverter out And the instantaneous voltage V of the AC network grid Calculating to obtain harmonic component V of output reference voltage of inverter ref_h (ii) a Step S200: according to the instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating to obtain fundamental component V of output reference voltage of inverter ref_f (ii) a Step S300: converting harmonic component V of output reference voltage of inverter ref_h And a fundamental component V ref_f AddingObtaining an output reference voltage V of the inverter ref (ii) a Step S400: according to the output reference voltage V of the inverter ref Generating PWM driving signal to control instantaneous output voltage V of the inverter out The harmonic component of (a). The harmonic suppression method provided by the invention can quickly track the change of the harmonic component of the voltage of the alternating current power grid and effectively suppress the harmonic component of the grid-connected output current.

Description

Inverter harmonic suppression method, controller and inverter
Technical Field
The invention belongs to the technical field of harmonic suppression, and particularly relates to an inverter harmonic suppression method, a controller and an inverter.
Background
The distributed power generation technology can integrate various renewable energy sources such as solar energy, wind energy and the like and various energy storage units, and the renewable energy sources and the various energy storage units are connected to a public bus through power electronic equipment such as an inverter and the like to form a micro power grid system, so that the high-efficiency utilization of energy sources is realized, and high-quality electric energy is provided for users. The system combines a distributed power generation unit, a distributed energy storage unit, a user load and a control system, and the whole micro power grid system is regarded as a load of a public power grid, so that the micro power grid system can be connected with the public power grid in a grid-connected mode, and can also be disconnected from the power grid to run independently when the public power grid is abnormal or needs to be overhauled (an island mode).
When the micro grid is in an island mode, the common bus is disconnected from the grid, usually a plurality of distributed units are required to work in a voltage source mode to ensure the quality of bus voltage and the stability and redundancy of the system, and meanwhile, a voltage source parallel operation control strategy is required to be introduced to realize accurate load power sharing of the plurality of voltage source distributed units and eliminate circulation current among the voltage source distributed units.
When the micro grid is in a grid-connected mode, the public power grid is directly connected with the distributed units. Because the voltage of the power grid can be equivalent to a relatively stable voltage source, the distributed power generation unit usually works in a current source mode, and the output current of the distributed power generation unit is accurately controlled according to the real-time change of the voltage of the public power grid, so that the effect of accurately controlling the grid-connected output power of the distributed power generation unit is realized.
However, when the distributed unit operates in the current source mode, the following disadvantages are encountered:
(1) When the micro-grid is in a grid-connected mode, the working mode of the current source is difficult to realize the function of participating in primary frequency modulation and voltage regulation of the micro-grid;
(2) When the micro grid is switched between a grid-connected mode and an island mode, the control mode of the distributed unit needs to be switched between a current source and a voltage source. In the dynamic process, the switching of the control strategy can cause the discontinuity of the driving signal of the switching tube at the switching moment, and the problems of impact, oscillation, drop, overshoot, frequency runaway and the like of the bus voltage or current during the switching action are easily caused.
Therefore, the prior art provides a method adopting a droop method grid-connected control strategy, so that the distributed unit works in a voltage source mode in a grid-connected mode, and the defect of current source grid-connected control is overcome. The droop method grid-connected control is developed based on a power flow control theory, and the basic principle is that the frequency and the effective value of output voltage are corrected by calculating active power and reactive power output by an inverter.
According to the power flow control theory, an equivalent circuit diagram of an inverter in a grid-connected mode is shown in fig. 1. In this figure, the inverter output voltage and the grid voltage are both simplified to an ideal voltage source with an internal resistance of 0. Left V rms ∠θ o Representing the output voltage of the inverter, and E & lt 0 at the right side representing the grid voltage, wherein V rms And E are the effective values of the output voltage of the inverter and the grid voltage, respectively, theta o Is the phase difference between the inverter output voltage and the grid voltage. Intermediate Z g ∠φ g Impedance of power output line for interconnecting inverter and power grid, i.e. line impedance, Z g Is the effective value of the link impedance, phi g Is the phase of the line impedance. In fig. 1, the inverter is simplified to an ideal voltage source with an internal resistance of 0.
When the connection impedance is a purely inductive impedance, i.e. + -.) g Equal to 90 DEG, impedance Z of power output line interconnecting inverter and grid g Is equal to L g I.e. the value of the wire inductance. At this time, the active power P output by the inverter o And reactive power can be expressed by the following formula:
Figure BDA0003830122660000021
according to the formula, the active power P output by the inverter o And the phase difference theta between the output voltage of the inverter and the grid voltage o Proportional relation, output reactive power Q o And inverter output voltage and powerDifference V between net voltage effective values rms Proportional relation of-E, ω g Representing the angular frequency of the inverter. Therefore, the controller of the inverter can control the active power output by the inverter by adjusting the phase of the output voltage, and control the reactive power output by the inverter by adjusting the effective value of the output voltage.
Therefore, in the conventional droop grid-connection control, the distributed unit in the form of a voltage source inverter passes through a fixed inductive connecting line impedance L g Is connected with a public power grid. The reference output active power and reactive power of the voltage source inverter are respectively P ref And Q ref I.e. the real and reactive power that the voltage source inverter should theoretically output, the values of which may be determined by the inverter depending on its operating state (e.g. the rated output power of the inverter or the current maximum output power of the distributed unit) or may be specified by a higher-level control unit (e.g. a microgrid control unit or a system administrator).
The controller of the voltage source inverter calculates the active power P output in real time by detecting the output voltage and the output current of the controller o And reactive power Q o Then, according to the formula:
Figure BDA0003830122660000031
frequency omega of self output voltage o And a valid value V rms Adjusting to realize the output grid-connected active power P o And reactive power Q o And (4) controlling. In the formula, ω r A nominal angular frequency representing the output voltage of the voltage source inverter; v r A nominal effective value representing the output voltage of the voltage source inverter; m is a unit of ω A droop coefficient representing an angular frequency of the voltage source inverter output voltage; n is V A droop coefficient representing an effective value of the voltage source inverter output voltage. Wherein, P o And P ref Deviation therebetween and Q o And Q ref The deviation between the two is the control precision of the inverter controller on the output active power and the output reactive power, and the larger the deviation is, the larger the deviation isThe worse the control accuracy.
Therefore, the traditional droop method grid-connected control strategy realizes the control of the output grid-connected active power and reactive power by adjusting the fundamental frequency and amplitude of the output voltage of the inverter.
However, the inverter output voltage controlled by the traditional droop method grid-connected control strategy is a standard sinusoidal voltage based on the fundamental frequency of the power grid, so that the method cannot control the harmonic component of the output voltage.
When the grid voltage has a harmonic component, the output voltage cannot be adjusted by the traditional droop grid-connected control strategy according to the harmonic component of the grid voltage, so that a large amount of grid-connected harmonic current caused by the harmonic component of the grid voltage can be generated in an inverter grid-connected system, and the harmonic component (namely harmonic power) of grid-connected output power is out of control. Meanwhile, the out-of-control of the grid-connected harmonic power can affect the calculation of the reactive power by the inverter controller, further affect the correction of the output voltage and finally affect the stability of the voltage source grid-connected system.
As can be seen from the above, in practical applications, the traditional droop method grid-connected control strategy cannot effectively suppress the output grid-connected harmonic power when the grid voltage has a harmonic component.
Disclosure of Invention
In order to solve the problems, the invention provides an inverter harmonic suppression method which can quickly track the change of the harmonic component of the voltage of an alternating current power grid and effectively suppress the harmonic component of the output current of an inverter.
In order to achieve the purpose, the invention mainly adopts the following technical scheme:
an inverter harmonic suppression method, comprising the steps of:
step S100: according to the instantaneous output voltage V of the inverter out And the instantaneous voltage V of the AC network grid Calculating harmonic component V of output reference voltage of inverter ref_h ；
Step S200: according to the instantaneous output voltage V of the inverter out And instantaneous deliveryOutput current I out Calculating a fundamental component V of an output reference voltage of an inverter ref_f ；
Step S300: converting harmonic component V of output reference voltage of inverter ref_h And fundamental component V ref_f Adding the voltage values to obtain an output reference voltage V of the inverter ref ；
Step S400: according to the output reference voltage V of the inverter ref Generating PWM driving signal to control instantaneous output voltage V of the inverter out The harmonic component of (a).
In some embodiments, the step S100 includes the steps of:
step S110: according to instantaneous output voltage V of inverter out Calculating harmonic component V of output voltage of inverter out_h ；
Step S120: according to the instantaneous voltage V of the AC network grid Calculating the harmonic component V of the AC mains voltage grid_h ；
Step S130: harmonic component V of the AC mains voltage grid_h And the harmonic component V of the output voltage of the inverter out_h Carrying out proportional resonance regulation after subtraction to obtain harmonic component V of output reference voltage of the inverter ref_h 。
In some embodiments, the step S200 includes the steps of:
step S210: according to instantaneous output voltage V of inverter out And instantaneous output current I out Calculating the active power P output by the inverter in the last control period o And reactive power Q o ；
Step S220: calculating the angular frequency omega of the output voltage in the current control period o And a valid value V rms The calculation formula is as follows:
Figure BDA0003830122660000041
wherein, ω is r Rated angular frequency, V, of the output voltage of the inverter r Is a rated effective value, m, of the output voltage of the inverter ω For the angular frequency droop coefficient, n, of the inverter output voltage v For inverter transmissionEffective value droop coefficient of output voltage, P ref Outputting active power, Q, for the reference of the inverter ref Outputting reactive power for the reference of the inverter;
step S230: according to the formula
Figure BDA0003830122660000042
Calculating fundamental component V of output reference voltage of inverter ref_f 。
In some embodiments, the step S110 includes the steps of:
step S111: according to the instantaneous output voltage V of the inverter out Calculating its fundamental component V out_f ；
Step S112: will the instantaneous output voltage V of the inverter out And the fundamental component V out_f The difference is taken from the first and the second,
obtaining harmonic component V of output voltage of inverter out_h 。
In some embodiments, the step S120 includes the steps of:
step S121: according to the instantaneous voltage V of the AC network grid Calculating its fundamental component V grid_f ；
Step S122: will exchange the instantaneous voltage V of the AC network grid And the fundamental component V grid_f Subtracting to obtain harmonic component V of AC power grid voltage grid_h 。
The present invention also provides a controller of an inverter, the controller including:
a harmonic component calculating unit for calculating a harmonic component according to the instantaneous output voltage V of the inverter out And the instantaneous voltage V of the AC network grid Calculating a harmonic component V of an output reference voltage of an inverter ref_h ；
A fundamental component calculating unit for calculating a fundamental component according to an instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating a fundamental component V of an output reference voltage of an inverter ref_f ；
A drive signal generation unit for generating a drive signal according to the output reference voltage V of the inverter ref Generating PWM driving signalControl the instantaneous output voltage V of the inverter out The harmonic component of (a).
In some embodiments, the harmonic component calculation unit includes:
a first fundamental component calculation module for calculating a first fundamental component from the instantaneous output voltage V of the inverter out Calculating its fundamental component V out_f ；
A second fundamental component calculation module for calculating the instantaneous voltage V of the AC power grid grid Calculating its fundamental component V grid_f ；
PR adjustment module for harmonic components V of the AC mains voltage grid_h And the harmonic component V of the output voltage of the inverter out_h The result obtained after subtraction is subjected to proportional resonance adjustment to obtain a harmonic component V of the output reference voltage of the inverter ref_h 。
In some embodiments, the fundamental component calculation unit includes:
a power calculation module for calculating the instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating the active power P output by the inverter in the last control period o And reactive power Q o ；
A third fundamental component calculation module for calculating the angular frequency omega of the output voltage in the current control period o And a valid value V rms And according to the angular frequency omega o And a valid value V rms Calculating a fundamental component V of an output reference voltage of an inverter ref_f 。
The invention provides an inverter, wherein the input end of the inverter is connected with a direct-current voltage source, the output end of the inverter is connected with an alternating-current power grid, the inverter comprises a DC/AC inverter circuit, the inverter also comprises the controller provided by the invention, the controller collects the instantaneous output voltage of the DC/AC inverter circuit and the instantaneous voltage of the alternating-current power grid in real time, a PWM (pulse width modulation) driving signal is generated, and the harmonic component of the instantaneous output voltage of the inverter is controlled.
The invention also provides an inverter which comprises the DC/AC inverter circuit and a controller, wherein the inverter adopts the harmonic suppression method provided by the invention to control the harmonic component of the instantaneous output voltage of the inverter.
Compared with the traditional droop method grid-connected control, the harmonic wave component of the output voltage of the inverter is controlled, the harmonic wave component of the output voltage of the inverter is ensured to be approximately equal to the harmonic wave component of the voltage of an alternating current power grid, and therefore the harmonic wave component of the grid-connected output current is effectively suppressed; when the harmonic component of the alternating current power grid voltage changes, the method can quickly track the change of the harmonic component of the power grid voltage, and effectively inhibit the dynamic change of the harmonic component of the grid-connected output current; the invention can adopt the resonance controller based on different resonance frequencies to realize the suppression of various current harmonic components, and has better control performance compared with the traditional proportional-integral control; meanwhile, the invention can also be used in combination with other improved droop method control, so as to realize the addition of beneficial effects.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings according to the drawings.
Fig. 1 is an equivalent circuit diagram of an inverter in a grid-connected mode.
Fig. 2 is a schematic block diagram of an inverter grid connection.
Fig. 3 is a structural diagram of a DC/AC inverter circuit.
Fig. 4 is a block diagram of the controller.
Fig. 5 is a flow chart of the inverter harmonic suppression method of the present invention.
Fig. 6 is a flowchart of calculating harmonic components of the inverter output reference voltage.
Fig. 7 is a flowchart of calculating the fundamental component of the inverter output reference voltage.
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Fig. 2 is a schematic block diagram of an inverter grid-connection, where the inverter includes a DC/AC inverter circuit 100 and a controller 200, the controller 200 outputs a driving signal PWM for controlling a switch in the DC/AC inverter circuit 100, and an output end of the DC/AC inverter circuit 100 is connected in parallel to an AC power grid 300. The controller 200 samples the output voltage u of the DC/AC inverter circuit 100 out And the voltage u of the ac network 300 grid And outputting a driving signal PWM after calculation.
Referring to fig. 3, which is a block diagram of an embodiment of the DC/AC inverter circuit 100 of the present invention, an input terminal of the DC/AC inverter circuit 100 is connected in parallel to a DC voltage V dc The output of which is connected to an ac grid 300, and an inverter 100 for converting a dc voltage V dc Converted to an ac voltage to power the ac power grid 300. The DC/AC inverter circuit 100 includes a full-bridge unit 120, and the controller 200 controls the on and off of each power switch device in the full-bridge unit 120, so as to control the output voltage of the inverter 100. In fig. 3, the midpoints of the three arms of the full-bridge unit 120 are respectively connected to the LC filter unit 130, and the inductive reactance L is g1 、L g2 、L g3 Each representing an equivalent inductive reactance of the ac power grid 300.
As shown in fig. 4, the controller 200 includes a harmonic component calculation unit 210, a fundamental component calculation unit 220, and a voltage adjustment unit 230, the harmonic component calculation unit 210 calculating a harmonic component V of a reference voltage ref.H The fundamental component calculation unit 220 calculates the fundamental component V of the reference voltage ref.f Harmonic component V of the reference voltage ref.H And the fundamental component V of the reference voltage ref.f The summed output reference voltage V ref . The voltage regulating unit 230 regulates the output voltage V according to the inverter out And a reference voltage V ref The output drive signal PWM is regulated. Thereby realizing the output of active power to the inverterPower P o And reactive power Q o And during control, the harmonic component of the output voltage of the voltage source inverter is controlled, so that the effect of inhibiting the harmonic component of the grid-connected output current of the inverter is realized.
The harmonic component calculation unit 210 includes a first fundamental component calculation module 211, a second fundamental component calculation module 212, and a PR adjustment module 213, and the first fundamental component calculation module 211 calculates the output voltage u according to the inverter out Calculating fundamental component V of output voltage of inverter out_f The second fundamental component calculation module 212 calculates the fundamental component from the voltage u of the ac power supply system grid Calculating a fundamental voltage component V of an AC power supply system grid_f Output voltage u of the inverter out Fundamental component V of output voltage of inverter out_f Obtaining the harmonic component V of the output voltage of the inverter after the subtraction of the subtraction module out_h From the voltage u of the AC mains grid Fundamental voltage component V to the AC mains grid_f Obtaining the voltage harmonic component V of the AC power grid after subtraction grid_h Harmonic component V of the voltage of the AC mains grid_h Harmonic component V of output voltage of inverter out_h The phases are subtracted by the subtraction module and then sent to the PR adjusting module 213 for adjusting operation to obtain the harmonic component V of the output voltage reference voltage of the inverter ref_h 。
The internal principle of the first fundamental component calculation module 211 is the same as that of the second fundamental component calculation module 212, and the calculation method of the first fundamental component calculation module 211 is as follows: calculating u out Effective value u of out_RMS (ii) a Calculating u by phase-locked loop out Phase of (a) out And according to theta out By a sine function sin (theta) out ) The voltage u is obtained by calculation out_pll (ii) a Will u out_RMS And u out_pll Multiplication to obtain u out Fundamental component V of out_f 。
The calculation method of the second fundamental component calculation module is as follows: calculating u grid Effective value u of grid_RMS (ii) a Calculating u by phase-locked loop grid Phase of (a) grid And according to theta grid By a sine function sin (theta) grid ) ComputingTo obtain a voltage u grid_pll (ii) a U is to be grid_RMS And u grid_pll Multiplication to obtain u grid Fundamental component V of grid_f 。
The PR adjustment module 213 is calculated as follows:
Figure BDA0003830122660000081
in the equation, V ref.H (s) and V dIf.H (s) are each V ref.H And V dIf.H A frequency domain representation of (a); k is a radical of p Is the proportionality coefficient of the harmonic compensation control algorithm; the variable i represents the harmonic order; omega h.i An angular frequency representing the ith harmonic; k R.i Resonance compensation coefficients representing a harmonic compensation control algorithm for the ith harmonic; omega c.i Representing the control bandwidth of the harmonic compensation control algorithm for the ith harmonic.
Fundamental component calculation unit the fundamental component calculation unit 220 comprises a power calculation module 221 and a third fundamental component calculation module 222, the power calculation module 221 being based on the output voltage u of the inverter out And the output current I of the inverter out Calculating active power P of inverter o And reactive power Q o The third fundamental component calculation module 222 calculates the active power P according to the inverter o And reactive power Q o Calculating to obtain fundamental component V of output voltage reference voltage of inverter ref_f The third fundamental component calculation module 222 calculates the angular frequency ω of the output voltage in the current control period using, for example, a conventional droop grid-connected control strategy or another improved droop grid-connected control strategy o And a valid value V rms The calculation formula is as follows:
Figure BDA0003830122660000082
wherein, ω is r Rated angular frequency, V, of the output voltage of the inverter r Is a rated effective value, m, of the output voltage of the inverter ω For the angular frequency droop coefficient, n, of the inverter output voltage v For output voltage of inverterEffective value droop coefficient, P ref Outputting active power, Q, for the reference of the inverter ref Outputting reactive power for the reference of the inverter; according to the formula
Figure BDA0003830122660000083
Calculating a fundamental component V of an output reference voltage of an inverter ref_f 。
It should be noted that, although not shown in fig. 4, the controller 200 further includes a circuit for collecting the instantaneous voltage V of the ac power grid grid The first voltage sampling circuit and the acquisition inverter instantaneous output voltage V out And a second voltage sampling circuit for sampling instantaneous output current I of the inverter out The current sampling circuit of (1).
For the inverter 200 and the controller 220 provided by the present invention, the present invention further provides a harmonic suppression method, as shown in fig. 4, the method includes the following steps:
step S100: according to the instantaneous output voltage V of the inverter out And the instantaneous voltage V of the AC network grid Calculating to obtain harmonic component V of output reference voltage of inverter ref_h ；
Step S200: according to the instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating to obtain fundamental component V of output reference voltage of inverter ref_f ；
In each control period, the controller 220 of the inverter calculates the fundamental component V of the output reference voltage of the inverter by using a traditional droop grid-connected control strategy or other improved droop grid-connected control strategies ref_f 。
Step S300: converting harmonic component V of output reference voltage of inverter ref_h And fundamental component V ref_f Adding the voltage values to obtain an output reference voltage V of the inverter ref ；
Step S400: according to the output reference voltage V of the inverter ref Generating PWM driving signal to control instantaneous output voltage V of the inverter out The harmonic component of (a).
As shown in fig. 5, the step S100 specifically includes the following steps:
step S110: according to the instantaneous output voltage V of the inverter out Calculating to obtain the harmonic component V of the output voltage of the inverter out_h ；
Calculating harmonic component V of output voltage of inverter out_h Firstly, according to instantaneous output voltage V of inverter out Calculating its fundamental component V out_f Then the instantaneous output voltage V of the inverter is converted into the voltage out And fundamental component V out_f Subtracting to obtain the harmonic component V of the output voltage of the inverter out_h 。
Step S120: according to the instantaneous voltage V of the AC network grid Calculating to obtain harmonic component V of AC power grid voltage grid_h ；
Calculating the harmonic component V of an AC mains voltage grid_h According to the instantaneous voltage V of AC network grid Calculating its fundamental component V grid_f Then the instantaneous voltage V of the AC network is converted into grid And a fundamental component V grid_f Subtracting to obtain harmonic component V of AC power grid voltage grid_h 。
Step S130: harmonic component V of AC network voltage grid_h And the harmonic component V of the output voltage of the inverter out_h Subtracting and then adjusting, wherein the adjusting is based on a quasi-proportional resonant controller, and the method comprises the following steps:
Figure BDA0003830122660000091
in the equation, V ref.H(s) And V dIf.H(s) Are each V ref.H And V dIf.H A frequency domain representation of (a); k is a radical of p Is the proportionality coefficient of the harmonic compensation control algorithm; the variable i represents the harmonic order; omega h.i An angular frequency representing the ith harmonic; k R.i Resonance compensation coefficients representing a harmonic compensation control algorithm for the ith harmonic; omega c.i Represents the control bandwidth of the harmonic compensation control algorithm for the ith harmonic; compensating and amplifying the difference value to obtain a harmonic component V of the output reference voltage of the inverter ref_h 。
As shown in fig. 6, the step S200 specifically includes the following steps:
step S210: according to the instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating to obtain the active power P output by the inverter in the last control period o And reactive power Q o ；
Step S220: calculating the angular frequency omega of the output voltage in the current control period o And a valid value V rms ；
The calculation formula is as follows:
Figure BDA0003830122660000101
wherein, ω is r Rated angular frequency, V, of the output voltage of the inverter r Is a rated effective value, m, of the output voltage of the inverter ω For the angular frequency droop coefficient, n, of the inverter output voltage v Is the droop coefficient, P, of the effective value of the output voltage of the inverter ref Outputting active power, Q, for the reference of the inverter ref And outputting reactive power for the reference of the inverter.
Step S230: according to the formula
Figure BDA0003830122660000102
Calculating to obtain fundamental component V of output reference voltage of inverter ref_f 。
By adopting the harmonic suppression method provided by the invention, the controller 220 acquires the instantaneous output voltage V of the inverter 200 in real time out And the instantaneous voltage V of the AC network grid Calculating the output reference voltage V of the inverter 200 in real time ref And according to the output reference voltage V ref Generating PWM driving signal in real time to control the on/off of power switch in inverter 200 circuit and continuously modify instantaneous output voltage V of inverter 200 out Thereby realizing the output of active power P to the inverter 200 o And reactive power Q o While controlling, the inverter 200 is controlled to instantaneously output the voltage V out The harmonic component of (a).
The inverter 200 provided by the present invention may be used in a microgrid, which may include a plurality of inverters 200, each inverter 200 is connected to a public power grid through a fixed connection impedance to supply power to the public power grid, each inverter 200 may include the controller 220 provided by the present invention, and the harmonic suppression method provided by the present invention is used to suppress the harmonic component of the inverter grid-connected output current.
It should be understood that the detailed description of the present invention is only for illustrating the present invention and is not limited by the technical solutions described in the embodiments of the present invention, and those skilled in the art should understand that the present invention can be modified or substituted equally to achieve the same technical effects; and are within the scope of the present invention as long as the requirements of use are met.

Claims (10)

1. An inverter harmonic suppression method, characterized by comprising the steps of:
step S100: according to the instantaneous output voltage V of the inverter out And the instantaneous voltage V of the AC network grid Calculating a harmonic component V of an output reference voltage of an inverter ref_h ；
Step S200: according to the instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating fundamental component V of output reference voltage of inverter ref_f ；
Step S300: converting harmonic component V of output reference voltage of inverter ref_h And fundamental component V ref_f Adding the voltage values to obtain an output reference voltage V of the inverter ref ；
Step S400: according to the output reference voltage V of the inverter ref Generating PWM driving signal to control instantaneous output voltage V of the inverter out The harmonic component of (a).
2. The inverter harmonic suppression method according to claim 1, wherein the step S100 includes the steps of:
step S110: according to the instantaneous output voltage V of the inverter out Calculating harmonic component V of output voltage of inverter out_h ；
Step S120: root of herbaceous plantAccording to the instantaneous voltage V of the AC network grid Calculating the harmonic component V of the AC mains voltage grid_h ；
Step S130: harmonic component V of the AC mains voltage grid_h And the harmonic component V of the output voltage of the inverter out_h Subtracting the harmonic component V to obtain the harmonic component V of the output reference voltage of the inverter ref_h 。
3. The inverter harmonic suppression method according to claim 1, wherein the step S200 includes the steps of:
step S210: according to instantaneous output voltage V of inverter out And instantaneous output current I out Calculating the active power P output by the inverter in the last control period o And reactive power Q o ；
Step S220: calculating the angular frequency omega of the output voltage in the current control period o And a valid value V rms The calculation formula is as follows:
Figure FDA0003830122650000011
wherein, ω is r Rated angular frequency, V, of the output voltage of the inverter r Is a rated effective value, m, of the output voltage of the inverter ω For the angular frequency droop coefficient, n, of the inverter output voltage v Is the droop coefficient, P, of the effective value of the output voltage of the inverter ref Outputting active power, Q, for the reference of the inverter ref Outputting reactive power for the reference of the inverter;
step S230: according to the formula
Figure FDA0003830122650000012
Calculating a fundamental component V of an output reference voltage of an inverter ref_f 。
4. The inverter harmonic suppression method according to claim 2, wherein the step S110 includes the steps of:
step S111: according to instantaneous output voltage V of inverter out Calculating its fundamental component V out_f ；
Step S112: will the instantaneous output voltage V of the inverter out And the fundamental component V out_f The difference is taken from the first and the second,
obtaining harmonic component V of output voltage of inverter out_h 。
5. The inverter harmonic suppression method according to claim 2, wherein the step S120 includes the steps of:
step S121: according to the instantaneous voltage V of the AC network grid Calculating its fundamental component V grid_f ；
Step S122: will exchange the instantaneous voltage V of the AC network grid And the fundamental component V grid_f Subtracting to obtain harmonic component V of AC power grid voltage grid_h 。
6. A controller for an inverter, the controller comprising:
a harmonic component calculating unit for calculating a harmonic component according to the instantaneous output voltage V of the inverter out And the instantaneous voltage V of the AC network grid Calculating a harmonic component V of an output reference voltage of an inverter ref_h ；
A fundamental component calculating unit for calculating a fundamental component according to an instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating a fundamental component V of an output reference voltage of an inverter ref_f ；
A drive signal generation unit for generating a drive signal according to the output reference voltage V of the inverter ref Generating PWM driving signal to control instantaneous output voltage V of the inverter out The harmonic component of (a).
7. The controller of the inverter according to claim 6, wherein the harmonic component calculation unit includes:
a first fundamental component calculation module for calculating a first fundamental component from the instantaneous output voltage V of the inverter out Calculating its fundamental component V out_f ；
A second fundamental component calculation module for calculating the instantaneous voltage V of the AC power grid grid Calculating its fundamental component V grid_f ；
PR adjustment module for harmonic component V of ac mains voltage grid_h And the harmonic component V of the output voltage of the inverter out_h The result obtained after subtraction is subjected to proportional resonance adjustment to obtain a harmonic component V of the output reference voltage of the inverter ref_h 。
8. The controller of the inverter according to claim 6, wherein the fundamental component calculation unit includes:
a power calculation module for calculating the instantaneous output voltage V of the inverter out And instantaneous output current I out Calculating the active power P output by the inverter in the last control period o And reactive power Q o ；
A third fundamental component calculation module for calculating angular frequency ω of the output voltage in the current control period o And a valid value V rms And according to angular frequency ω o And a valid value V rms Calculating a fundamental component V of an output reference voltage of an inverter ref_f 。
9. An inverter, the input end of which is connected to a direct-current voltage source, and the output end of which is connected to an alternating-current power grid, the inverter comprising a DC/AC inverter circuit, characterized in that the inverter further comprises a controller according to any one of claims 6-8, the controller collects the instantaneous output voltage of the DC/AC inverter circuit and the instantaneous voltage of the alternating-current power grid in real time, generates a PWM driving signal, and controls the harmonic component of the instantaneous output voltage of the inverter.
10. An inverter comprising a DC/AC inverter circuit and a controller, wherein the inverter controls a harmonic component of an instantaneous output voltage of the inverter using the harmonic suppression method according to any one of claims 1 to 5.
CN202211070770.4A 2022-09-02 2022-09-02 Inverter harmonic suppression method, controller and inverter Pending CN115313494A (en)

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