CN111682543A - Active filter for dead-beat control based on weighted average current and control method - Google Patents

Active filter for dead-beat control based on weighted average current and control method Download PDF

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CN111682543A
CN111682543A CN202010449016.6A CN202010449016A CN111682543A CN 111682543 A CN111682543 A CN 111682543A CN 202010449016 A CN202010449016 A CN 202010449016A CN 111682543 A CN111682543 A CN 111682543A
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current
filter
grid
weighted average
pcc
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姬忠凯
何晋伟
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Tianjin University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • 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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
    • 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
    • Y02E40/30—Reactive power compensation
    • 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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Abstract

The invention discloses an active filter based on weighted average current dead-beat control and a control method thereof, wherein the active filter comprises a three-phase full-bridge converter consisting of six power switch modules (IGBT), the three-phase full-bridge converter is connected with a PCC (point of common coupling) through an LCL (inductor capacitor) filter and then is connected with a power grid, the DC side of the three-phase full-bridge converter is connected with a DC power supply, and the LCL filter is composed of a filter inductor L positioned on the three-phase full-bridge converter side1Filter inductance L on the side of power grid2And a filter capacitor CfThe nonlinear load is connected with the filter inductor L1And a filter inductor L2The connection point between them.

Description

Active filter for dead-beat control based on weighted average current and control method
Technical Field
The invention relates to the technical field of harmonic compensation electric energy quality, in particular to a novel active filter dead-beat control method based on weighted average current, which compensates harmonic current so as to improve electric energy quality.
Background
Nowadays, with the rapid development of new energy sources such as wind power, photovoltaic and the like, the scale of a micro-grid is larger and larger, and the control requirement on the micro-grid is higher and higher. The traditional distributed unit (DG) only needs to provide active power and reactive power for a power grid, but as more and more power electronic devices are used and local loads are connected, the harmonic content of grid-connected current is rich, and the problem of electric energy quality is more and more severe, so that the distributed unit (DG) needs to be added with complex control to solve the problem of electric energy quality.
This problem is usually solved by means of a filter. Passive filters are being gradually replaced by active power filters due to their large size, large power consumption, and inflexible control. Multifunctional power converters in Distributed Generation (DG) require compensation for local load harmonic currents, similar to the operation of conventional active power filters. By effectively controlling the distributed units, the harmonic compensation method is more flexible and diversified, is less influenced by system parameters, has high response speed and realizes dynamic compensation. But the extraction of the harmonic current of the load and the complex algorithm of the controller at the same time increase the computational burden of the controller, which is undoubtedly a burden for a low-cost controller with limited computational power.
In addition, the conventional PI controller-based active power filter is limited in gain and system bandwidth due to the influence of the resonant frequency of the LCL filter, otherwise the system is easily unstable. To ensure the stability of the system, the dynamic performance is affected: the dynamic response characteristic of the current sensor is slow, and the change of harmonic current cannot be tracked quickly, so that the application range of the current sensor is limited. In order to achieve a faster and more accurate control effect, a more excellent control algorithm is required to improve the dynamic performance of the system on the premise of ensuring the stability of the system.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide an active filter based on dead-beat control of weighted average current and a control method.
The purpose of the invention is realized by the following technical scheme:
the active filter based on weighted average current dead-beat control comprises a three-phase full-bridge converter consisting of six power switch modules (IGBTs), wherein the three-phase full-bridge converter is connected with a public connection Point (PCC) through an LCL filter and then is connected with a power grid, a direct current power supply is connected to the direct current side of the three-phase full-bridge converter, and the direct current power supply is connected to the direct current side of the three-phase full-bridge converterThe LCL filter is composed of a filter inductor L positioned on the side of a three-phase full-bridge converter1Filter inductance L on the side of power grid2And a filter capacitor CfThe nonlinear load is connected with the filter inductor L1And a filter inductor L2The connection point between them.
Also provided is a technical scheme as follows, the active filter dead-beat control method based on the weighted average current comprises the following steps:
according to the phase-locked loop link, obtaining the voltage V of the power grid through a voltage sensorPCCPhase angle theta ofpccAnd a frequency f; current sensor measuring filter inductance L1Current I of1Filter inductance L2On grid-connected current I2And is combined with1And I2Digital quantity I after Clark coordinate transformation1,αβAnd I2,αβSending to a controller;
the controller compensates harmonic waves by adopting a dead-beat control method based on weighted average current, and calculates to obtain the output reference voltage of the three-phase full-bridge converter
Figure BDA0002506834840000021
The controller calculates the reference voltage
Figure BDA0002506834840000022
And then, comparing the three-phase full-bridge converter with the triangular wave according to Sinusoidal Pulse Width Modulation (SPWM) or Space Vector Pulse Width Modulation (SVPWM) to obtain a duty ratio signal of the switching tube, thereby controlling the switching-on and switching-off of the switching tube of the three-phase full-bridge converter.
The steps are as follows:
step 1, determining reference current in a two-axis static coordinate system according to a formula (1) and a formula (2), and enabling the reference current and a power grid voltage phase angle theta to be equalpccThe synchronization is as follows:
Figure BDA0002506834840000023
Figure BDA0002506834840000024
wherein I2,ref,αAnd I2,ref,βIs the reference grid current in the two-axis stationary coordinate system; thetapccThe phase angle of the grid voltage is obtained by a phase-locked loop based on a second-order generalized integrator; vPCCIs the measured PCC voltage amplitude, PrefAnd QrefThe reference values of the output active power and reactive power of the grid-connected inverter are obtained;
step 2, calculating the weighted average current as follows, and acquiring the filter inductance L at the side of the three-phase full-bridge converter under a two-axis static coordinate system1Current I of1,αβFilter inductance L on the network side2On grid-connected current I2,αβCarrying out weighted average to obtain weighted average current I12,αβThe expression is as follows:
I12,αβ＝γI1,αβ+(1-γ)I2,αβ(3)
wherein gamma represents weight coefficient and represents filter inductance L at three-phase full-bridge converter side1The ratio of the total inductance of the inductor in the LCL filter is calculated as shown in a formula (4);
Figure BDA0002506834840000031
and 3, obtaining a formula (5) by a circuit structure of the LCL filter according to the kirchhoff current law as follows:
I1,αβ＝I2,αβ+Ic,αβ+Iload,αβ(5)
wherein, I1,αβRepresenting the filter inductance L on the converter side flowing in a two-axis stationary coordinate system1Current of (I)2,αβRepresenting the filter inductance L at the side of the power grid under a two-axis static coordinate system2On the grid current, Ic,αβShowing the filtered wave capacitance C flowing under a two-axis stationary coordinate systemfCurrent of (I)load,αβRepresenting the current flowing through the local load under a two-axis stationary frame;
substituting equation (5) into equation (3) can result in equation (6):
I12,αβ＝I2,αβ+γ(Ic,αβ+Iload,αβ)＝I2,αβ+γ·Icomp,αβ(6)
as can be seen from equation (6), the weighted average current I12,αβIs a grid-connected current I2,αβAnd a compensation current Icomp,αβComposition is carried out; i iscomp,αβRepresenting filter capacitor current Ic,αβAnd load harmonic current Iload,αβSum of capacitance current I due to filteringc,αβMuch smaller than the load harmonic current Iload,αβNeglecting;
and 4, rapidly controlling the current by adopting a dead-beat control method based on the weighted average current, wherein the principle is as follows: the output voltage of the inverter is controlled, the grid-connected current is indirectly controlled, and the discrete expression of the dead-beat control is shown as a formula (7);
Figure BDA0002506834840000032
wherein, under the two-axis static coordinate system,
Figure BDA0002506834840000033
indicating the output voltage of the inverter at the k-th beat, VPCC_ave,αβ(k) Represents the average value of the PCC node voltage at the kth beat, which is represented by the kth beat node voltage VPCC,αβ(k) 1.5 times of the voltage V of the kth-1 nodePCC,αβ0.5 times of (k-1) is calculated as I12_ref,αβ(k) The reference value representing the weighted average current of the kth beat is developed according to equation (6), I2_ref,αβ(k) Reference value, I, representing the grid-connected current of the kth beatcomp,αβ(k) Representing the compensation value, T, of the harmonic current of the kth beatsRepresenting the switching frequency of the inverter.
Further, the compensation current I in formula (6)comp,αβHarmonic extraction is performed using a resonant controller having a transfer function of
Figure BDA0002506834840000041
Wherein the variable s is a Laplace operator, h is the harmonic frequency, and the low-order harmonic in the power system is 5, 7, 11 and 13 times; k is a radical ofihIs the resonant gain at the h harmonic frequency; omegacutIs the bandwidth of the resonant controller; omegafIs the angular frequency, omega, of the fundamental frequencyf＝2πf；f＝50Hz。
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1. the LCL filter is reduced from a third-order system to a first-order system by a weighted average current method, the resonance peak value is suppressed by increasing damping, the robustness and the stability of the system are enhanced, the gain of a control system is improved, the bandwidth of the system is increased, and the design of a high-gain controller is facilitated;
2. the control method realizes the rapid and accurate control of the current, increases the dynamic response of the system, and can carry out power control while compensating harmonic waves;
3. the load harmonic current is used as a compensation term of the reference voltage, so the compensation term does not influence the design of the controller, and the compensation term and the controller can be designed independently.
Drawings
Fig. 1 is a schematic diagram of a circuit structure of an active power filter and a control method thereof according to the present invention;
FIG. 2 shows the three-phase grid voltage V before and after the active power filter performs the control method according to the inventionPCCThree-phase network current I2Load current IloadAnd a compensation current IcompA waveform diagram of (a);
FIG. 3 shows three-phase grid voltage V when the active power filter compensates for harmonics while providing active power to the gridPCCThree-phase network current I2Load current IloadAnd a compensation current IcompA waveform diagram of (a).
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention is applied to the circuit topology structure and the electrical connection mode of the active filter as described below: six power switch modules (IGBT) form a three-phase full-bridge converter, and the three-phase full-bridge converter is connected with a public connection point PCC through an LCL filter and then is connected with a power grid, wherein the direct current side of the three-phase full-bridge converter is connected with a bus capacitor or a photovoltaic direct current power supply, and the like, and the LCL filter is composed of a converter side filter inductor L1Electric network side filter inductor L2And a filter capacitor CfThe nonlinear load is connected with the filter inductor L on the converter side1And power grid side filter inductor L2The voltage of the power grid and the filter inductance L at the converter side are acquired by a voltage and current sensor1And power grid side filter inductor L2The current of (a);
the method for compensating harmonics of the circuit arrangement described above is characterized by the following steps:
step 1: firstly, according to a phase-locked loop link, obtaining a power grid voltage V through a voltage sensorPCCPhase angle theta ofpccAnd a frequency f; the current sensor then measures the converter-side filter inductance L1Current I of1Filter inductance L on the network side2On grid-connected current I2And subjecting it to Clark coordinate transformation to obtain digital quantity I1,αβAnd I2,αβSending to a controller;
step 2: determining reference current in a two-axis stationary coordinate system by the formula (1) and the formula (2), and setting the reference current to a voltage phase angle theta of a power gridpccThe synchronization is as follows:
Figure BDA0002506834840000051
Figure BDA0002506834840000052
wherein I2,ref,αAnd I2,ref,βIs the reference grid current in a two-axis stationary coordinate system. ThetapccIs power grid electricity obtained by a phase-locked loop based on a second-order generalized integratorPhase compression angle. VPCCIs the measured PCC voltage amplitude, PrefAnd QrefAnd the reference values of the output active power and reactive power of the grid-connected inverter are obtained.
And step 3: the detailed calculation process of the weighted average current is as follows. Under a two-axis static coordinate system, the collected filter inductor L on the side of the converter1Current I of1,αβFilter inductance L on the network side2On grid-connected current I2,αβCarrying out weighted average to obtain weighted average current I12,αβThe expression is as follows:
I12,αβ＝γI1,αβ+(1-γ)I2,αβ(3)
wherein gamma represents a weight coefficient and represents a filter inductance L on the converter side1The ratio of the total inductance of the inductor in the LCL filter is calculated as shown in a formula (4);
Figure BDA0002506834840000053
and 4, step 4: from the circuit structure of the LCL filter, equation (5) can be derived from kirchhoff's current law, as follows:
I1,αβ＝I2,αβ+Ic,αβ+Iload,αβ(5)
wherein, I1,αβRepresents the current, I, flowing through the transducer-side filter inductor L1 in a two-axis stationary frame2,αβRepresenting the grid-connected current in a two-axis stationary frame, Ic,αβShowing the filtered wave capacitance C flowing under a two-axis stationary coordinate systemfCurrent of (I)load,αβRepresenting the current flowing through the local load under a two-axis stationary frame;
substituting equation (5) into equation (3) yields equation (6), and from equation (6), the weighted average current I12,αβIs a grid-connected current I2,αβAnd a compensation current Icomp,αβAnd (4) forming. I iscomp,αβRepresenting filter capacitor current Ic,αβAnd load harmonic current Iload,αβSum, in general, filter capacitor current Ic,αβMuch smaller than the loadHarmonic current Iload,αβIt can be ignored;
I12,αβ＝I2,αβ+γ(Ic,αβ+Iload,αβ)＝I2,αβ+γ·Icomp,αβ(6)
and 5: for the compensation current I in the formula (6)comp,αβA resonant controller is employed. Since the resonant controller has a higher gain at the resonant frequency, the resonant controller is used for extracting harmonic waves, and the transfer function of the resonant controller is
Figure BDA0002506834840000061
Wherein the variable s is a Laplace operator, h is the harmonic frequency, and the main low-order harmonics in the power system are 5, 7, 11 and 13; k is a radical ofihIs the resonant gain at the h harmonic frequency; omegacutIs the bandwidth of the resonant controller; omegafIs the angular frequency, omega, of the fundamental frequencyf＝2πf，f＝50Hz；
Step 6: the control method can accurately and quickly control the current and improve the dynamic performance of the control system; the principle of the controller is briefly described as follows: the output voltage of the inverter is controlled, the grid-connected current is indirectly controlled, and the discrete expression of the dead-beat control is shown as a formula (8);
Figure BDA0002506834840000062
wherein, under the two-axis static coordinate system,
Figure BDA0002506834840000063
indicating the output voltage of the inverter at the k-th beat, VPCC_ave,αβ(k) Represents the average value of the PCC node voltage at the kth beat, which is represented by the kth beat node voltage VPCC,αβ(k) 1.5 times of the voltage V of the kth-1 nodePCC,αβ0.5 times of (k-1) is calculated as I12_ref,αβ(k) The reference value representing the weighted average current of the kth beat is developed according to equation (6), I2_ref,αβ(k) A reference value representing the kth beat grid-connected current,Icomp,αβ(k) representing the compensation value, T, of the harmonic current of the kth beatsRepresenting the switching frequency of the inverter.
And 7: after the reference voltage of the controller is obtained, the reference voltage is compared with the triangular wave according to Sinusoidal Pulse Width Modulation (SPWM) or Space Vector Pulse Width Modulation (SVPWM) to obtain a duty ratio signal of the switching tube, so that the switching-on and switching-off of the switching tube of the converter are controlled.
A simulation model shown in figure 1 is built by Matlab/Simulink, and the control method of the active power filter provided by the invention is verified.
As shown in fig. 2, the converter only works as an active filter, and harmonic compensation is not used before 0.5s, so that it can be found that the current of the power grid is consistent with the current of the nonlinear load due to the fact that the active filter does not work, and the current of the power grid is seriously distorted; after the function of the harmonic compensation at the time of 0.5s, the current of the power grid is obviously sinusoidal.
The THD of the current of the power grid is reduced from 35.78% to 4.9% before and after harmonic compensation of the converter, and the fact that the harmonic current of the load is almost compensated by the active power filter is shown.
As shown in fig. 3, the active filter outputs active or reactive power while compensating for harmonic current, and as can be seen from the figure, the harmonic of the grid-connected current is well compensated while providing active or reactive power to the grid, and only the waveform diagram of the output active power is given. After the function of the harmonic compensation at the time of 0.5s, the current of the power grid is obviously sinusoidal. The THD of the current of the power grid is reduced to 4.5% from 22.84% before and after harmonic compensation of the converter, and the fact that the harmonic current of the load is almost compensated by the active power filter is shown.
In conclusion, the novel active filter dead-beat control method based on the weighted average current is feasible and improves the electric energy quality. The control method provided by the invention uses a dead beat control method to improve the dynamic performance of the system, uses a control method of weighted average current to reduce an LCL three-order system into a first-order system, and increases damping to inhibit resonance, thereby improving the gain of the control system, increasing the bandwidth of the system and being beneficial to the design of a high-gain controller. Meanwhile, active power or reactive power can be provided for the power grid, so that the converter can be simultaneously applied to occasions of power control and power quality control.
The present invention is not limited to the above-described embodiments. The foregoing description of the specific embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above specific embodiments are merely illustrative and not restrictive. Those skilled in the art can make many changes and modifications to the invention without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (4)

1. The active filter based on weighted average current dead-beat control is characterized in that a three-phase full-bridge converter is formed by six power switch modules (IGBTs), the three-phase full-bridge converter is connected to a Point of Common Coupling (PCC) through an LCL filter and then is connected with a power grid, a direct current power supply is connected to the direct current side of the three-phase full-bridge converter, and the LCL filter is composed of a filter inductor L positioned on the side of the three-phase full-bridge converter1Filter inductance L on the side of power grid2And a filter capacitor CfThe nonlinear load is connected with the filter inductor L1And a filter inductor L2The connection point between them.
2. The active filter dead-beat control method based on the weighted average current is characterized by comprising the following steps of:
according to the phase-locked loop link, obtaining the voltage V of the power grid through a voltage sensorPCCPhase angle theta ofpccAnd a frequency f; current sensor measuring filter inductance L1Current I of1Filter inductance L2On grid-connected current I2And is combined with1And I2Digital quantity I after Clark coordinate transformation1，αβAnd I2，αβSending to a controller;
the controller compensates harmonic waves by adopting a dead-beat control method based on weighted average current, and the output reference of the three-phase full-bridge converter is obtained through calculationVoltage of
Figure FDA0002506834830000011
And comparing the Sine Pulse Width Modulation (SPWM) or Space Vector Pulse Width Modulation (SVPWM) with the triangular wave to obtain a duty ratio signal of the switching tube, thereby controlling the switching-on and switching-off of the switching tube of the three-phase full-bridge converter.
3. The method for controlling an active filter based on dead-beat control of weighted average current according to claim 2, comprising the steps of:
step 1, determining reference current in a two-axis static coordinate system according to a formula (1) and a formula (2), and enabling the reference current and a power grid voltage phase angle theta to be equalpccThe synchronization is as follows:
Figure FDA0002506834830000012
Figure FDA0002506834830000013
wherein I2，ref，αAnd I2，ref，βIs the reference grid current in the two-axis stationary coordinate system; thetapccThe phase angle of the grid voltage is obtained by a phase-locked loop based on a second-order generalized integrator; vPccIs the measured PCC voltage amplitude, PrefAnd QrefThe reference values of the output active power and reactive power of the grid-connected inverter are obtained;
step 2, calculating the weighted average current as follows, and acquiring the filter inductance L at the side of the three-phase full-bridge converter under a two-axis static coordinate system1Current I of1，αβFilter inductance L on the network side2On grid-connected current I2，αβCarrying out weighted average to obtain weighted average current I12，αβThe expression is as follows:
I12，αβ＝＝γI1，αβ+(1-γ)I2，αβ(3)
wherein gamma represents weight coefficient and represents filter inductance L at three-phase full-bridge converter side1The ratio of the total inductance of the inductor in the LCL filter is calculated as shown in a formula (4);
Figure FDA0002506834830000021
and 3, obtaining a formula (5) by a circuit structure of the LCL filter according to the kirchhoff current law as follows:
I1,αβ＝I2,αβ+Ic,αβ+Iload,αβ(5)
wherein, I1,αβRepresenting the filter inductance L on the converter side flowing in a two-axis stationary coordinate system1Current of (I)2,αβRepresenting the filter inductance L at the side of the power grid under a two-axis static coordinate system2On the grid current, Ic,αβShowing the filtered wave capacitance C flowing under a two-axis stationary coordinate systemfCurrent of (I)load,αβRepresenting the current flowing through the local load under a two-axis stationary frame;
substituting equation (5) into equation (3) can result in equation (6):
I12,αβ＝I2,αβ+γ(Ic,αβ+Iload,αβ)＝I2,αβ+γ·Icomp,αβ(6)
as can be seen from equation (6), the weighted average current I12,αβIs a grid-connected current I2,αβAnd a compensation current Icomp,αβComposition is carried out; i iscomp,αβRepresenting filter capacitor current Ic,αβAnd load harmonic current Iload,αβSum of capacitance current I due to filteringc,αβMuch smaller than the load harmonic current Iload,αβNeglecting;
and 4, rapidly controlling the current by adopting a dead-beat control method based on the weighted average current, wherein the principle is as follows: the output voltage of the inverter is controlled, the grid-connected current is indirectly controlled, and the discrete expression of the dead-beat control is shown as a formula (7);
Figure FDA0002506834830000022
wherein, under the two-axis static coordinate system,
Figure FDA0002506834830000023
indicating the output voltage of the inverter at the k-th beat, VPCC_ave,αβ(k) Represents the average value of the PCC node voltage at the kth beat, which is represented by the kth beat node voltage VPCC,αβ(k) 1.5 times of the voltage V of the kth-1 nodePCC,αβ0.5 times of (k-1) is calculated as I12_ref,αβ(k) The reference value representing the weighted average current of the kth beat is developed according to equation (6), I2_ref,αβ(k) Reference value, I, representing the grid-connected current of the kth beatcomp,αβ(k) Representing the compensation value, T, of the harmonic current of the kth beatsRepresenting the switching frequency of the inverter.
4. The method for controlling an active filter based on weighted average current deadbeat control of claim 3, wherein the compensation current I in equation (6)comp,αβHarmonic extraction is performed using a resonant controller having a transfer function of
Figure FDA0002506834830000031
Wherein the variable s is a Laplace operator, h is the harmonic frequency, and the low-order harmonics in the power system are 5, 7, 11 and 13; k is a radical ofihIs the resonant gain at the h harmonic frequency; omegacutIs the bandwidth of the resonant controller; omegafIs the angular frequency, omega, of the fundamental frequencyf＝2πf；f＝50Hz。
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CN112290567A (en) * 2020-12-23 2021-01-29 西南交通大学 Three-phase power quality compensation device and method based on half-bridge converter

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