CN102738798A - Harmonic oscillation suppression method and device for power grid - Google Patents

Abstract

The invention belongs to the technical field of harmonic suppression of a power grid and discloses a harmonic oscillation suppression method for the power grid. The method comprises the following steps of: detecting electrical parameters of the power grid at an output end of an active power filter (APF) arranged at the tail end of a transmission line, and acquiring instruction current of phases a, b and c of the APF according to the electrical parameters; and subtracting the instruction current and the actual output current of the APF, performing PI control on the difference, performing pulse width modulation (PWM), so as to obtain the three-phase bridge arm driving signal of the APF, and controlling a converter according to the driving signal. The invention also discloses a harmonic oscillation suppression device for the power grid. The harmonic oscillation of the power grid is suppressed from a bran-new view, and a scheme of suppressing the harmonic oscillation of the power grid is completed. The length of the transmission line of the power grid is equivalently elongated, so that reflected waves are reduced even eliminated, the harmonic oscillation is avoided, and particularly the harmonic oscillation can be well suppressed when the characteristic impedance of the transmission line of the power grid is slightly changed.

Description

A kind of mains by harmonics oscillation suppression method and device

Technical field

The invention belongs to mains by harmonics and suppress technical field, when slight the variation takes place in particularly a kind of mains by harmonics oscillation suppression method and device, especially electrical network transmission line characteristic impedance, also can good restraining harmonic oscillation.

Background technology

Nonlinear load increasing introduced the lot of background harmonic wave to electrical network.During the electrical network underloading, background harmonics is propagated in electrical network harmonic oscillation is taken place probably, seriously jeopardizes electric capacity, inductive devices in the electrical network.

At present; Major part inhibition strategy to this harmonic oscillation all is based on R-APF (Resistance-Active Power Filter; Resistive Active Power Filter-APF), a series of papers that suppress about mains by harmonics of delivering such as the red wood of Japanese scholar safe literary composition based on above-mentioned control thought.The present invention suppresses the vibration of electrical network background harmonics from a new angle.

Summary of the invention

The technical problem that (one) will solve

The technical problem that the present invention will solve provides a kind of mains by harmonics oscillation suppression method and device, to overcome the defective of background harmonics generation harmonic oscillation in electrical network is propagated in the prior art.

(2) technical scheme

In order to achieve the above object, the invention provides a kind of mains by harmonics oscillation suppression method, said method comprising the steps of:

A, detect the electrical quantity of the output electrical network of the APF (Active Power Filter, Active Power Filter-APF) be installed in line end, and obtain a, the b of Active Power Filter-APF, the instruction current of c three-phase according to said electrical quantity;

B, instruction current and actual active electric power filter to output current are done poor; Said difference is carried out PI (Proportional-Integral; Proportional integral) carries out PWM (Pulse Width Modulation after the control; Pulse-width modulation) modulation obtains Active Power Filter-APF three-phase brachium pontis drive signal, according to said drive signal control current transformer.

Wherein, in said steps A, specifically comprise:

A1, detection are installed in the output line voltage u of the Active Power Filter-APF of line end _a, u _b, u _cAnd current i _a, i _b, i _c, separate obtaining harmonic voltage content u _Ah, u _Bh, u _ChHarmonic electric current content i _Ah, i _Bh, i _Ch

A2, with k ₁A phase harmonic current i doubly _AhWith k ₂A phase harmonic voltage u doubly _AhIt is poor to do, difference i _Af=k ₁i _Ah-k ₂u _AhAs the instruction current of a phase Active Power Filter-APF, in like manner obtain the b of Active Power Filter-APF, the instruction current i of c two phases _Bf=k ₁i _Bh-k ₂u _Bh, i _Cf=k ₁i _Ch-k ₂u _ChK wherein ₁, k ₂Be the instruction current coefficient.

Wherein, in said steps A 1, specifically comprise:

A11, according to formula

$\left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\\ -\cos \mathrm{\ωt}& -\sin \mathrm{\ωt}\end{array}\right]\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]$

Obtain component of voltage u with the voltage transformation under three phase coordinate systems down, to two cordic phase rotators system _d, u _q, wherein ω obtains through phase-locked loop;

A12, according to formula

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\\ -\cos \mathrm{\ωt}& -\sin \mathrm{\ωt}\end{array}\right]\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

Obtain current component i with the current transformation under three phase coordinate systems down, to two cordic phase rotators system _d, i _q, wherein ω obtains through phase-locked loop;

A13, u to obtaining _d, u _qAnd i _d, i _qCarry out filtering, extract its harmonic content

With

A14, according to formula

$\left[\begin{array}{c}{u}_{\mathrm{ah}}\\ u_{\mathrm{bh}}\\ u_{\mathrm{ch}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{cc}\cos \mathrm{\ωt}& \sin \mathrm{\ωt}\\ \sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\end{array}\right]\left[\begin{array}{c}{\tilde{u}}_d\\ {\tilde{u}}_q\end{array}\right]$

Voltage transformation under the two cordic phase rotators system under three phase coordinate systems, is obtained harmonic voltage content u _Ah, u _Bh, u _Ch, wherein ω obtains through phase-locked loop;

A15, according to formula

$\left[\begin{array}{c}{i}_{\mathrm{ah}}\\ i_{\mathrm{bh}}\\ i_{\mathrm{ch}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{cc}\cos \mathrm{\ωt}& \sin \mathrm{\ωt}\\ \sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\end{array}\right]\left[\begin{array}{c}{\tilde{i}}_d\\ {\tilde{i}}_q\end{array}\right]$

Current transformation under the two cordic phase rotators system under three phase coordinate systems, is obtained harmonic current content i _Ah, i _Bh, i _Ch, wherein ω obtains through phase-locked loop.

Wherein, in said steps A 2, at known transmission line characteristic impedance z _cThe time, said instruction current coefficient k ₁, k ₂Value mode be: k is set ₁/ k ₂=z _c

Wherein, in said steps A 2, be difficult for obtaining transmission line characteristic impedance z _cOr z _cWhen changeable, said instruction current coefficient k ₁, k ₂Value mode be: get k ₁, k ₂Be big multiple, and can whether meet the demands according to the mains by harmonics situation of vibrating and adjust.

Wherein, said instruction current coefficient k ₁Value is greater than 10.

Wherein, in said steps A, specifically comprise:

Detection is installed in the output power network current i of the Active Power Filter-APF of line end _a, i _b, i _c, said electric current multiply by m, after obtain the instruction current i of Active Power Filter-APF under three phase coordinates _Ah, i _Bh, i _Ch, wherein m is a current coefficient, gets the real number greater than 1.

The present invention also provides a kind of mains by harmonics vibration suppression device, and said device comprises:

Active Power Filter-APF, said Active Power Filter-APF is installed in line end;

The electrical parameters detection unit is connected with said Active Power Filter-APF, is used to detect the electrical quantity of the output electrical network of said Active Power Filter-APF;

The instruction current acquiring unit is connected with said electrical parameters detection unit, is used for obtaining a, the b of Active Power Filter-APF, the instruction current of c three-phase according to said electrical quantity;

The PI control unit is connected with Active Power Filter-APF with said instruction current acquiring unit respectively, and it is poor to be used for instruction current and actual active electric power filter to output current are done, and said difference is carried out PI control;

The drive signal acquiring unit is connected with said PI control unit, is used for the result after the said PI control is carried out the PWM modulation, obtains Active Power Filter-APF three-phase brachium pontis drive signal;

The current transformer control unit is connected with said drive signal acquiring unit, is used for according to said drive signal control current transformer.

(3) beneficial effect

Compare based on the parallel connection type active electric filter of voltage detecting with tradition, the present invention all has more excellent inhibition effect when in circuit characteristic impedance change and transmission line, adding harmonic current source when having inherited its advantage.The present invention comes mains by harmonics vibration is suppressed from a brand-new angle, perfect inhibition scheme to the mains by harmonics vibration.The present invention prolongs the electrical network length of transmission line through equivalence, reduces even the elimination reflected wave, has avoided the generation of harmonic oscillation, when especially slight the variation takes place in the electrical network transmission line characteristic impedance, and also can good restraining harmonic oscillation.

Description of drawings

Fig. 1 is the flow chart of a kind of mains by harmonics oscillation suppression method of the embodiment of the invention one;

Fig. 2 is the flow chart of a kind of mains by harmonics oscillation suppression method of the embodiment of the invention two;

Fig. 3 is the structure chart of a kind of mains by harmonics vibration suppression device of the embodiment of the invention three;

Fig. 4 is an artificial antenna long transmission line equivalent schematic of the present invention;

Fig. 5 the present invention is based on wireless long transmission line control strategy control APF scheme of installation;

Fig. 6 is that APF instruction current of the present invention generates block diagram;

Fig. 7 is Active Power Filter-APF of the present invention and Current Control link sketch map;

Fig. 8 is that the present invention is at the different k of 9km transmission line ₁(k ₂) harmonic wave inhibition analogous diagram;

Fig. 9 a is that line characteristics impedance of the present invention is when diminishing and R-APF harmonic suppression effect comparison diagram;

Fig. 9 b is that line characteristics impedance of the present invention is when becoming big and R-APF harmonic suppression effect comparison diagram;

Figure 10 is the present invention and harmonic current source, R-APF harmonic suppression effect comparison diagram.

Embodiment

Below in conjunction with accompanying drawing and embodiment, specific embodiments of the invention describes in further detail.Following examples are used to explain the present invention, but are not used for limiting scope of the present invention.

The present invention at first detects the electrical quantity of the output electrical network of the Active Power Filter-APF that is installed in line end, and obtains a, the b of Active Power Filter-APF, the instruction current of c three-phase according to said electrical quantity; It is poor then instruction current and actual active electric power filter to output current to be done, and said difference is carried out carrying out the PWM modulation after the PI control, obtains Active Power Filter-APF three-phase brachium pontis drive signal, according to said drive signal control current transformer.

Embodiment one

The mains by harmonics oscillation suppression method of present embodiment is as shown in Figure 1, may further comprise the steps:

In said steps A, specifically comprise:

Step s101, detection is installed in the output line voltage u of the Active Power Filter-APF of line end _a, u _b, u _cAnd current i _a, i _b, i _c, separate obtaining harmonic voltage content u _Ah, u _Bh, u _ChHarmonic electric current content i _Ah, i _Bh, i _ChIn the present embodiment, specifically comprise:

(1) according to formula

$\left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\\ -\cos \mathrm{\ωt}& -\sin \mathrm{\ωt}\end{array}\right]\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]$

Obtain component of voltage u with the voltage transformation under three phase coordinate systems down, to two cordic phase rotators system _d, u _q, wherein ω obtains through phase-locked loop;

(2) according to formula

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\\ -\cos \mathrm{\ωt}& -\sin \mathrm{\ωt}\end{array}\right]\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

Obtain current component i with the current transformation under three phase coordinate systems down, to two cordic phase rotators system _d, i _q, wherein ω obtains through phase-locked loop;

(3) u to obtaining _d, u _qAnd i _d, i _qCarry out filtering, extract its harmonic content

With

(4) according to formula

$\left[\begin{array}{c}{u}_{\mathrm{ah}}\\ u_{\mathrm{bh}}\\ u_{\mathrm{ch}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{cc}\cos \mathrm{\ωt}& \sin \mathrm{\ωt}\\ \sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\end{array}\right]\left[\begin{array}{c}{\tilde{u}}_d\\ {\tilde{u}}_q\end{array}\right]$

Voltage transformation under the two cordic phase rotators system under three phase coordinate systems, is obtained harmonic voltage content u _Ah, u _Bh, u _Ch, wherein ω obtains through phase-locked loop;

(5) according to formula

$\left[\begin{array}{c}{i}_{\mathrm{ah}}\\ i_{\mathrm{bh}}\\ i_{\mathrm{ch}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{cc}\cos \mathrm{\ωt}& \sin \mathrm{\ωt}\\ \sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\end{array}\right]\left[\begin{array}{c}{\tilde{i}}_d\\ {\tilde{i}}_q\end{array}\right]$

Current transformation under the two cordic phase rotators system under three phase coordinate systems, is obtained harmonic current content i _Ah, i _Bh, i _Ch, wherein ω obtains through phase-locked loop.

Step s102 is with k ₁A phase harmonic current i doubly _AhWith k ₂A phase harmonic voltage u doubly _AhIt is poor to do, difference i _Af=k ₁i _Ah-k ₂u _AhAs the instruction current of a phase Active Power Filter-APF, in like manner obtain the b of Active Power Filter-APF, the instruction current i of c two phases _Bf=k ₁i _Bh-k ₂u _Bh, i _Cf=k ₁i _Ch-k ₂u _ChK wherein ₁, k ₂Be the instruction current coefficient.Said instruction current coefficient k ₁, k ₂Value mode be: at known transmission line characteristic impedance z _cThe time, k is set ₁/ k ₂=z _cBe difficult for obtaining transmission line characteristic impedance z _cOr z _cWhen changeable, said instruction current coefficient k ₁, k ₂Value mode be: get k ₁, k ₂Be big multiple, and can whether meet the demands according to the mains by harmonics situation of vibrating and adjust.Instruction current coefficient k in the present embodiment ₁Value is greater than 10.

Step s103, it is poor that instruction current and actual active electric power filter to output current are done, and said difference is carried out carrying out the PWM modulation after the PI control, obtains Active Power Filter-APF three-phase brachium pontis drive signal, according to said drive signal control current transformer.

Embodiment two

The mains by harmonics oscillation suppression method of present embodiment is as shown in Figure 2, may further comprise the steps:

Step s201, detection is installed in the output power network current i of the Active Power Filter-APF of line end _a, i _b, i _c, said electric current multiply by the instruction current i that obtains Active Power Filter-APF under three phase coordinates behind the m _Af, i _Bf, i _Cf, wherein m gets the real number greater than 1.

Step s202, it is poor that instruction current and actual active electric power filter to output current are done, and said difference is carried out carrying out the PWM modulation after the PI control, obtains Active Power Filter-APF three-phase brachium pontis drive signal, according to said drive signal control current transformer.

Embodiment three

A kind of mains by harmonics vibration suppression device of present embodiment is as shown in Figure 3, comprises Active Power Filter-APF, electrical parameters detection unit, instruction current acquiring unit, PI control unit, drive signal acquiring unit and current transformer control unit; Wherein, said Active Power Filter-APF is installed in line end; Said electrical parameters detection unit is connected with said Active Power Filter-APF, is used to detect the electrical quantity of the output electrical network of said Active Power Filter-APF; Said instruction current acquiring unit is connected with said electrical parameters detection unit, is used for obtaining a, the b of Active Power Filter-APF, the instruction current of c three-phase according to said electrical quantity; Said PI control unit is connected with Active Power Filter-APF with said instruction current acquiring unit respectively, and it is poor to be used for instruction current and actual active electric power filter to output current are done, and said difference is carried out PI control; Said drive signal acquiring unit is connected with said PI control unit, is used for the result after the said PI control is carried out the PWM modulation, obtains Active Power Filter-APF three-phase brachium pontis drive signal; Said current transformer control unit is connected with said drive signal acquiring unit, is used for according to said drive signal control current transformer.

Core concept of the present invention is: equivalence prolongs transmission line, weakens even the harmonic carcellation reflected wave, to reach the purpose that suppresses harmonic oscillation.

Basic principle of the present invention is following:

The voltage u of the voltage known transmission line point of known certain point in the transmission line theory ₀With magnitude of current i ₀, then apart from this some distance be for the electric current and voltage of x along voltage, current spread direction:

$\left.\begin{array}{c}u={\mathrm{<figure-callout\; id="0"\; label="u"\; filenames="HDA00001715820600022.png,HDA00001715820600051.png"\; state="\{\{state\}\}">u</figure-callout>}}_0\cosh \left(\mathrm{\&gamma;x}\right)-{\mathrm{<figure-callout\; id="0"\; label="z\; c\; i"\; filenames="HDA00001715820600022.png,HDA00001715820600051.png"\; state="\{\{state\}\}">z</figure-callout>}}_c{i}_{}{}_0\sinh \left(\mathrm{\&gamma;x}\right)\\ i=i_0\cosh \left(\mathrm{\&gamma;x}\right)-{\mathrm{<figure-callout\; id="0"\; label="u"\; filenames="HDA00001715820600022.png,HDA00001715820600051.png"\; state="\{\{state\}\}">u</figure-callout>}}_0/z_c\sinh \left(\mathrm{\&gamma;x}\right)\end{array}\right\}---\left(1\right)$

Wherein, z _cBe the line characteristics impedance.

In the transmission line theory,, then there is not reflected wave, do not have harmonic oscillation if length of transmission line is infinitely great.Based on this thought and formula (1), the present invention is directed to mains by harmonics, add controlled voltage source and current source at line end; Simulation prolongs the situation of transmission line; When the prolongation distance is enough big, can vibrate by harmonic carcellation, isoboles is as shown in Figure 4; Wherein the value of controlled voltage source u and controlled current source i is suc as formula (2), u ₀, i ₀Be line end harmonic voltage and electric current:

$\left.\begin{array}{c}u=[{\mathrm{<figure-callout\; id="0"\; label="u"\; filenames="HDA00001715820600022.png,HDA00001715820600051.png"\; state="\{\{state\}\}">u</figure-callout>}}_0\cosh \left(\mathrm{\&gamma;x}\right)-{\mathrm{<figure-callout\; id="0"\; label="Z\; c\; i"\; filenames="HDA00001715820600022.png,HDA00001715820600051.png"\; state="\{\{state\}\}">Z</figure-callout>}}_c{i}_{}{}_0\sinh \left(\mathrm{\&gamma;x}\right)]-u_0\\ i=[{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="HDA00001715820600022.png,HDA00001715820600051.png"\; state="\{\{state\}\}">i</figure-callout>}}_0\cosh \left(\mathrm{\&gamma;x}\right)-{\mathrm{<figure-callout\; id="0"\; label="u"\; filenames="HDA00001715820600022.png,HDA00001715820600051.png"\; state="\{\{state\}\}">u</figure-callout>}}_0/Z_c\sinh \left(\mathrm{\&gamma;x}\right)]-i_0\end{array}\right\}---\left(2\right)$

To transmission line, based on alternative theorem, only get final product the effect of equivalent controlled current source and controlled voltage source with controlled current source, as shown in Figure 5, the controlled current source expression formula is following:

i=k ₁i ₀-k ₂u ₀

Wherein:

$\left.\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HDA00001715820600051.png,HDA00001715820600052.png"\; state="\{\{state\}\}">k</figure-callout>}}_1=\cosh \left(\mathrm{\&gamma;x}\right)-1\\ {\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="HDA00001715820600031.png,HDA00001715820600051.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=\sinh \left(\mathrm{\&gamma;x}\right)/Z_c\end{array}\right\}---\left(3\right)$

Can find out k from formula (3) ₁, k ₂Value big more, the line length that equivalence prolongs is big more, works as k ₁Got 10 o'clock, the length of transmission line that equivalence prolongs has reached 100km, and the humorous wave reflection of this moment is very faint, but Approximate Equivalent endless transmission line.

Fig. 6 has provided the sketch map that instruction current generates, and Fig. 7 is APF structure and Current Control link.

Different line lengths are carried out emulation, provided the simulation result of 9km transmission line below.

Fig. 8 has provided different k ₁, k ₂, to the effect of harmonic wave inhibition, along with k ₁, k ₂Increase, equivalent extending length is big more, more near ideal situation, it is good more to suppress effect.

When Fig. 9 a and Fig. 9 b changed for the line characteristics impedance, the present invention and traditional R-APF were to the inhibition effect of harmonic wave, and no matter how transmission line characteristic impedance changes, and the present invention is better than traditional R-APF on the whole.

Possibly have some harmonic source loads in the circuit, Figure 10 has provided after the 3km place adds the harmonic current source load, and the present invention and traditional R-APF suppress situation to harmonic wave, and inhibition effect of the present invention still is superior to traditional R-APF.

Compare based on the parallel connection type active electric filter of voltage detecting with tradition, the present invention all has more excellent inhibition effect when in circuit characteristic impedance change and transmission line, adding harmonic current source when having inherited its advantage.The present invention comes mains by harmonics vibration is suppressed from a brand-new angle, perfect inhibition scheme to the mains by harmonics vibration.The present invention prolongs the electrical network length of transmission line through equivalence, reduces even the elimination reflected wave, has avoided the generation of harmonic oscillation, when especially slight the variation takes place in the electrical network transmission line characteristic impedance, and also can good restraining harmonic oscillation.

The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from know-why of the present invention; Can also make some improvement and replacement, these improvement and replacement also should be regarded as protection scope of the present invention.

Claims (8)

1. a mains by harmonics oscillation suppression method is characterized in that, said method comprising the steps of:

A, detect the electrical quantity of the output electrical network of the Active Power Filter-APF be installed in line end, and obtain a, the b of Active Power Filter-APF, the instruction current of c three-phase according to said electrical quantity;

B, instruction current and actual active electric power filter to output current are done poor, said difference is carried out carrying out the PWM modulation after the PI control, obtain Active Power Filter-APF three-phase brachium pontis drive signal, according to said drive signal control current transformer.

2. mains by harmonics oscillation suppression method according to claim 1 is characterized in that, in said steps A, specifically comprises:

A1, detection are installed in the output line voltage u of the Active Power Filter-APF of line end _a, u _b, u _cAnd current i _a, i _b, i _c, separate obtaining harmonic voltage content u _Ah, u _Bh, u _ChHarmonic electric current content i _Ah, i _Bh, i _Ch

A2, with k ₁A phase harmonic current i doubly _AhWith k ₂A phase harmonic voltage u doubly _AhIt is poor to do, difference i _Af=k ₁i _Ah-k ₂u _AhAs the instruction current of a phase Active Power Filter-APF, in like manner obtain the b of Active Power Filter-APF, the instruction current i of c two phases _Bf=k ₁i _Bh-k ₂u _Bh, i _Cf=k ₁i _Ch-k ₂u _ChK wherein ₁, k ₂Be the instruction current coefficient.

3. mains by harmonics oscillation suppression method according to claim 2 is characterized in that, in said steps A 1, specifically comprises:

A11, according to formula

$\left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& -\cos \mathrm{\&omega;t}\\ -\cos \mathrm{\&omega;t}& -\sin \mathrm{\&omega;t}\end{array}\right]\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]$

Obtain component of voltage u with the voltage transformation under three phase coordinate systems down, to two cordic phase rotators system _d, u _q, wherein ω obtains through phase-locked loop;

A12, according to formula

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& -\cos \mathrm{\&omega;t}\\ -\cos \mathrm{\&omega;t}& -\sin \mathrm{\&omega;t}\end{array}\right]\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

Obtain current component i with the current transformation under three phase coordinate systems down, to two cordic phase rotators system _d, i _q, wherein ω obtains through phase-locked loop;

A13, u to obtaining _d, u _qAnd i _d, i _qCarry out filtering, extract its harmonic content

With

A14, according to formula

$\left[\begin{array}{c}{u}_{\mathrm{ah}}\\ u_{\mathrm{bh}}\\ u_{\mathrm{ch}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{cc}\cos \mathrm{\&omega;t}& \sin \mathrm{\&omega;t}\\ \sin \mathrm{\&omega;t}& -\cos \mathrm{\&omega;t}\end{array}\right]\left[\begin{array}{c}{\tilde{u}}_d\\ {\tilde{u}}_q\end{array}\right]$

Voltage transformation under the two cordic phase rotators system under three phase coordinate systems, is obtained harmonic voltage content u _Ah, u _Bh, u _Ch, wherein ω obtains through phase-locked loop;

A15, according to formula

$\left[\begin{array}{c}{i}_{\mathrm{ah}}\\ i_{\mathrm{bh}}\\ i_{\mathrm{ch}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{cc}\cos \mathrm{\&omega;t}& \sin \mathrm{\&omega;t}\\ \sin \mathrm{\&omega;t}& -\cos \mathrm{\&omega;t}\end{array}\right]\left[\begin{array}{c}{\tilde{i}}_d\\ {\tilde{i}}_q\end{array}\right]$

Current transformation under the two cordic phase rotators system under three phase coordinate systems, is obtained harmonic current content i _Ah, i _Bh, i _Ch, wherein ω obtains through phase-locked loop.

4. according to claim 2 or 3 described mains by harmonics oscillation suppression methods, it is characterized in that, in said steps A 2, at known transmission line characteristic impedance z _cThe time, said instruction current coefficient k ₁, k ₂Value mode be: k is set ₁/ k ₂=z _c

5. according to claim 2 or 3 described mains by harmonics oscillation suppression methods, it is characterized in that, in said steps A 2, be difficult for obtaining transmission line characteristic impedance z _cOr z _cWhen changeable, said instruction current coefficient k ₁, k ₂Value mode be: get k ₁, k ₂Be big multiple, and can whether meet the demands according to the mains by harmonics situation of vibrating and adjust.

6. mains by harmonics oscillation suppression method according to claim 5 is characterized in that, said instruction current coefficient k 1 value is greater than 10.

7. mains by harmonics oscillation suppression method according to claim 1 is characterized in that, in said steps A, specifically comprises:

Detection is installed in the output power network current i of the Active Power Filter-APF of line end _a, i _b, i _c, said electric current multiply by m, after obtain the instruction current i of Active Power Filter-APF under three phase coordinates _Ah, i _Bh, i _Ch, wherein m is a current coefficient, gets the real number greater than 1.

8. a mains by harmonics vibration suppression device is characterized in that, said device comprises:

Active Power Filter-APF, said Active Power Filter-APF is installed in line end;

The electrical parameters detection unit is connected with said Active Power Filter-APF, is used to detect the electrical quantity of the output electrical network of said Active Power Filter-APF;

The instruction current acquiring unit is connected with said electrical parameters detection unit, is used for obtaining a, the b of Active Power Filter-APF, the instruction current of c three-phase according to said electrical quantity;

The PI control unit is connected with Active Power Filter-APF with said instruction current acquiring unit respectively, and it is poor to be used for instruction current and actual active electric power filter to output current are done, and said difference is carried out PI control;

The drive signal acquiring unit is connected with said PI control unit, is used for the result after the said PI control is carried out the PWM modulation, obtains Active Power Filter-APF three-phase brachium pontis drive signal;

The current transformer control unit is connected with said drive signal acquiring unit, is used for according to said drive signal control current transformer.

Images