CN101552471A - Harmonic current absorber - Google Patents

Abstract

The present invention disclose a harmonic current absorber, including. shunt circuit and series circuit, the shunt circuit is composed by capacitance C1 and reactor L1 in parallel connection, and the shunt circuit connects with one more reactor L2 to form the series circuit, the parallel section is parallel resonance in fundamental frequency to prevent the fundamental current going through; the shunt connection section and the series connection section have a almost zero low impedance in specific subharmonic frequency, being able to absorb specific subharmonic current and implementing harmonic management in the harmonic source. The invention can manage harmonic in the harmonic source, and presents a closely open circuit high impedance characteristic in fundamental frequency, which greatly reducing wastage of base wave and reactor. At the same time, the invention possess favourable integrated impedance frequency characteristics, being able to maintain preferable filtering impression when occurring frequency deviation and detune, and possessing the high filtering characteristic, and possessing a certain filtering impression to higher harmonic current.

Description

Harmonic current absorber

Technical field

The present invention relates to a kind of harmonic current absorber.

Background technology

At present, power electronic device such as diode, thyristor, IGBT have obtained increasing application in various confessions with electrical domain, and this has improved the flexible and controllable of electricity supply and use equipment to a certain extent, has optimized the technical performance of electricity supply and use equipment.But meanwhile, because power electronic device unintentional nonlinearity characteristic, make increasing electricity supply and use equipment become harmonic wave and produce the source, interference effect to electrical network becomes more and more serious, also becoming increasingly complex, the power supply quality that this has worsened electrical network has to a certain extent influenced other power consumption equipments and electricity consumption client in the same electrical network.In electric power system, harmonic pollution and electromagnetic interference, power factor reduction have become three big public hazards.The method of traditional solution harmonic pollution problem generally is at utility network points of common connection place and connects various types of harmonic wave suppression equipments, mainly be divided into passive filter and active filter two classes, this filter apparatus has solved harmonic wave preferably to the pollution that utility network caused, but does not solve harmonic wave from the source that harmonic wave produces to harm that main electricity supply and use equipment caused.Particularly, and various types of impedance Control type harmonic wave suppression equipments of connecing changed the impedance structure of electric power networks to a certain extent, because the objective reality of the factors such as harmonic wave amplification that the series/parallel resonance under electrical network background harmonics and the potential specific subfrequency causes makes traditional filtering mode easily bring hidden danger concerning the safe operation of electric power system.Simultaneously, existing filtering absorption plant is for the requirement that reaches reasonable engineering design and the reactive power of compensated part capacity, must be by the fundamental current of certain content, thus caused waste of energy to a certain extent.

Summary of the invention

In order to solve the above-mentioned technical problem that existing harmonic wave absorption plant exists, the invention provides a kind of effective harmonic current absorber.Apparatus of the present invention are very low impedance under harmonic frequency, specific subharmonic is had good assimilation effect; And, under fundamental frequency, be approximate high-impedance behavior of opening a way, can stop fundamental current to pass through.

The technical solution adopted for the present invention to solve the technical problems is: comprise parallel circuits and series circuit, described parallel circuits is composed in parallel by capacitor C 1 and reactor L1, parallel circuits is formed series circuit with a reactor L2 again, and the value of capacitor C 1 and reactor L1 need satisfy $L_1=\frac{1}{{\mathrm{\&omega;}}^2{C}_1},$ Reactance value L ₂With capacitance C ₁Value need satisfy ${\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20091004257200081.png,A20091004257200082.png"\; state="\{\{state\}\}">L</figure-callout>}}_2=\frac{1}{(h^2-1){\mathrm{\&omega;}}^2{C}_1},$ H is a harmonic number.

In the above-mentioned harmonic current absorber, comprise the harmonic current absorber of a plurality of parallel connections, the harmonic number of each harmonic current absorber is inequality.

Technique effect of the present invention is: the resonance frequency of parallel circuits is a fundamental frequency among the present invention, can stop fundamental current to pass through, reduce the first-harmonic loss, series circuit is very low impedance to selected specific subfrequency simultaneously, can the specific subharmonic current of filtering, after a plurality of such harmonic current absorber parallel connections, can the main specific subharmonic current of filtering, can be suppressed harmonic wave at harmonic wave generation source place like this, avoid it to scurry into utility network and enlarge harm.In addition, the present invention compares with traditional passive filter, also has better impedance frequency characteristic, near tuned frequency, has lower impedance behavior, reduce the harmful effect of off resonance greatly, and in high order harmonic component frequency band, be Low ESR, for high order harmonic component than broad to filter effect, have the low-impedance characteristic of high pass, can be in very wide harmonic frequency section the filtering higher harmonic current.In addition, reactor of the present invention can adopt the superconduction reactor, makes essentially no first-harmonic loss of harmonic wave absorption plant and reactor loss.

The present invention is further illustrated below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the electrical schematic diagram of the embodiment of the invention 1.

Fig. 2 is the electrical schematic diagram of the embodiment of the invention 2.

Fig. 3 is the comprehensive impedance frequency characteristic of the embodiment of the invention 2.

Fig. 4 is the comprehensive impedance frequency characteristic partial enlarged drawing of the embodiment of the invention 2.

Embodiment

Referring to Fig. 1, the present invention includes parallel circuits and series circuit, described parallel circuits is composed in parallel by capacitor C 1 and reactor L1, and parallel circuits is formed series circuit with a reactor L2 again.In order to reach the prevention fundamental current, reduce the purpose of first-harmonic loss, the reactor of part in parallel and capacitor need to satisfy parallel resonance under fundamental frequency condition, that is:

$Z_{L1}+Z_{C1}=\mathrm{j\&omega;}{L}_1+\frac{1}{\mathrm{j\&omega;}{C}_1}=0---\left(1\right)$

The reactance value and the capacitance that can get part reactor in parallel thus satisfy following relation:

$L_1=\frac{1}{{\mathrm{\&omega;}}^2{C}_1}---\left(2\right)$

For effective filtering h subharmonic current, part in parallel should satisfy following relation with the comprehensive harmonic impedance of part of devices under the h subfrequency of connecting:

$h{Z}_{L1}+\frac{Z_{C1}}{h}+Z_{L2h}=\mathrm{j\&omega;h}{L}_1+\frac{1}{\mathrm{j\&omega;h}{C}_1}+\mathrm{j\&omega;<figure-callout\; id="2"\; label="h\; L"\; filenames="A20091004257200081.png,A20091004257200082.png"\; state="\{\{state\}\}">h</figure-callout>}{L}_{}{}_2=0---\left(3\right)$

Can get the reactance value L of reactor in the series circuit by following formula convolution (2) ₂With parallel circuits capacitance C ₁Should satisfy following relation:

${\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20091004257200081.png,A20091004257200082.png"\; state="\{\{state\}\}">L</figure-callout>}}_2=\frac{1}{(h^2-1){\mathrm{\&omega;}}^2{C}_1}---\left(4\right)$

Formula (2), (4) have characterized harmonic current absorber when stoping fundamental current, absorption h subharmonic current, part in parallel and series connection part of devices required satisfied impedance restriction relation when basic parameter designs.

Simultaneously, in order to reduce the first-harmonic loss and the harmonic loss of harmonic pad, the reactor of part in parallel and series connection part can adopt the superconduction reactor, and its quality factor q ₁And Q ₂Should satisfy following relation:

$Q_1=\frac{{\mathrm{\&omega;L}}_1}{R_1}\&GreaterEqual;1000---\left(5\right)$

${\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="A20091004257200081.png,A20091004257200082.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2=\frac{{\mathrm{\&omega;L}}_2}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="A20091004257200081.png,A20091004257200082.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}\&GreaterEqual;1000---\left(6\right)$

When practical application, harmonic characterisitic according to nonlinear load, in order to absorb corresponding main subharmonic current, the normally many covers of harmonic current absorber harmonic current absorber shown in Figure 1 composes in parallel, as shown in Figure 2, among the figure and three harmonic current absorbers that connect be respectively applied for and absorb 5,7,11 subharmonic currents, and stop fundamental current simultaneously.

Fig. 3,4 is depicted as the comprehensive impedance frequency characteristic and the partial enlarged drawing thereof of harmonic current absorber among Fig. 2 embodiment.As seen from the figure, harmonic current absorber is Low ESR near absorption frequency, this means, even have certain frequency deviation or off resonance, the present invention still has certain filter effect for harmonic current; And, under the high order harmonic component frequency, still have lower impedance characteristic, this means that the present invention has the performance of high-pass filtering, even do not increase high pass filter, still high order harmonic component is had certain filter effect.

Claims (3)

1. harmonic current absorber, it is characterized in that: comprise parallel circuits and series circuit, described parallel circuits is composed in parallel by capacitor C 1 and reactor L1, and parallel circuits is formed series circuit with a reactor L2 again, and the value of capacitor C 1 and reactor L1 need satisfy $L_1=\frac{1}{{\mathrm{\&omega;}}^2{C}_1},$ Reactance value L ₂With capacitance C ₁Value need satisfy $L_2=\frac{1}{(h^2-1){\mathrm{\&omega;}}^2{C}_1},$ H is a harmonic number.

2. harmonic current absorber according to claim 1 is characterized in that: comprise the harmonic current absorber of a plurality of parallel connections, the harmonic number of each harmonic current absorber is inequality.

3. harmonic current absorber according to claim 1 is characterized in that: described reactor L1, L2 are the superconduction reactor.

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