CN2746626Y - Active electric filtering device - Google Patents

Abstract

The utility model discloses an active electric filtering device, comprising a current conversion circuit, an instruction current arithmetic circuit, a compensating current occurrence circuit, an automatic limiter circuit and a display-operating controller. The instruction current arithmetic circuit is composed of a first 2 phases/2 phases coordinate converter and a second 2 phases/2 phases coordinate converter which are respectively connected with a sine occurrence circuit and a cosine occurrence circuit connected in manner of phase-locked loop; a 3 phases/2 phases coordinate converter is connected with a first low-pass filter and a second low-pass filter in parallel by the first 2 phases/2 phases coordinate converter, and the second 2 phases/2 phases coordinate converter is connected with a 2 phases/3 phases coordinate converter; a n-times doubling circuit which is connected in front of the phase-locked loop is also included, the n-times doubling circuit converts power supply voltage ea to frequency signals, the frequency signals magnifies for n times, and n subharmonic currents are obtained.

Description

Active electric filter device

Technical field

The utility model relates to a kind of device of effective elimination mains by harmonics, belongs to a kind of active electric filter device.

Background technology

Along with the develop rapidly of electronic technology, the application of various electronic installations in electric power system, industry, traffic and family is increasingly extensive, and harmonic current and reactive current are injected electrical network in a large number, and the harm that causes is serious day by day.Harmonic current strengthens loss, and heating is serious, shortened equipment life, and equipment breakdown is frequent, jeopardizes the safe operation of electric power system and communication system, and the power factor wretched insufficiency, and the quality of power supply worsens, and utilization rate of electrical reduces greatly, causes economic loss serious.Therefore, administer the important subject that harmonic wave and compensating reactive power have become fields such as current power electronic technology, electric power system, electric automatization, Theoretical Electrotechnics.All the time, people generally adopt passive filtration unit to absorb the harmonic current that harmonic source (non-linear load) is produced.The effectively harm of harmonic carcellation of traditional LC passive filter (being called for short PF), but this device itself exists many deficiencies and defective: as the harmonic wave of passive electric filtering device pointer to specific frequency; Exist possibility with electrical network generation resonance; Variation to electric network impedance and frequency is very responsive; Volume is big, loss is big etc.Now, many experts and scholars and engineers and technicians solve power quality problem at the adjustable device of research trends.Wherein the most representative is exactly active power filtering (hereinafter to be referred as APF).The active power filtering technical role is a key technology of improving power supply quality, practice has been arranged abroad, domestic research to active filter substantially also is in the technical research stage at present, the active electric filter device that the applicant develops, measuring the current signal that source (non-linear load) takes place for electrical network or harmonic wave, by calculating harmonic components wherein, produce at last one with the anti-phase constant amplitude of harmonic wave harmonic current offset with it, thereby reach the purpose of harmonic carcellation.Owing in the harmonic wave that load produces high order harmonic component and low-order harmonic are arranged, high order harmonic component is as 11,13,17,19,21,23,25,31 subharmonic etc., low-order harmonic as, 5 times, 7 subharmonic etc.For 6 impulse commutations load commonly used, 5 subharmonic currents account for the 20-22% of fundamental current, and 7 subharmonic currents account for the 11-15% of fundamental current, and the shared component of other high order harmonic component is less than 1/h (h is a harmonic number).The switching frequency of the used high power switch power electronic element of APF is 5-6KHZ, thereby higher to the filter effect of the harmonic wave of low number of times, and as to 5 times and 7 times, its filtering rate is more than 90%; The filter effect of higher harmonics is lower, as to 11 times, 13 times be more than 50%, lower to the corresponding meeting of filtering rate effect of high order harmonic component more.Therefore be used in low order filtering in the capacity set with APF, will give full play to the technical advantage of APF.If all above-mentioned harmonic waves are compensated with APF, need very big capacity, the capacity of aggrandizement apparatus, cost make that also along with increase the price of this device is just very expensive.In order to reduce cost, the applicant just inserts the electric network synthetic utilization to APF and passive filtration unit (hereinafter to be referred as PF) in actual use.Its principle is that the control compensation of APF is only at than low-order harmonic, as 5 times, 7 times; The control compensation of PF is only at higher harmonics, as 11,13,17,19,21,23,25,31,33 subharmonic etc.APF wants to carry out Selective Control, could realize the comprehensive utilization of APF+PF.

Summary of the invention

The purpose of this utility model provides a kind of active electric filter device that can carry out Selective Control.

The purpose of this utility model is achieved in that it is to comprise current converter circuit, instruction current computing circuit, offset current generation circuit, automatically amplitude limiter circuit, demonstration and operation control; The instruction current computing circuit comprise that phase-locked loop connects just, cosine generation circuit the one 2 phase/2 phase coordinates converters, the 22 phase/2 phase coordinates converters that connect respectively, 3 phases/2 phase coordinates converters are by the one 2 phase/2 phase coordinates converters and connect first low pass filter, second low pass filter; The 22 phase/2 phase coordinates converters connect 2 phases/3 phase coordinates converters, also are included in the n frequency multiplier circuit that phase-locked loop connects previously, by the n frequency multiplier circuit supply voltage ea are converted to frequency signal, and frequency signal amplifies n doubly, obtains the nth harmonic electric current at last.

Of the present utility model owing to the energy Selective Control, only produce the anti-phase harmonic current of low order, do not make comprehensive waveform compensation, all the other high orders parts are absorbed and compensating reactive power by PF.The APF that dynamic property is good, the big low-order harmonic electric current of amount has been given full play to the effect of APF in the corresponding load current, reduces the integrated cost of APF greatly.

Description of drawings

Fig. 1 is the theory diagram of the utility model embodiment

Fig. 2 is the alternative instruction current computing circuit schematic diagram of the utility model embodiment

Fig. 3 is the schematic diagram of the detection mode of the utility model embodiment

Among the figure: 1-be current converter circuit 2-be instruction current operator circuit 3-be automatic amplitude limiter circuit 4-be offset current generation circuit 5-be show and operation control * ih-be harmonic current detection signal ih '-be compensation harmonic electric current N-be n frequency multiplier circuit PLL-phase-locked loop sin, cos-be just, cosine generation circuit C ₃₂-2 phases/3 phase coordinates converter Cn-the one 2 phase/2 phase coordinates converter LPF-, the first low pass filter LPF-, the second low pass filter C ^-1N-the 22 phase/2 phase coordinates converter C ₂₃-2 phases/3 phase coordinates converter ea-are supply voltage ia, ib, ic-is three-phase current signal ia, i β-be a of electric current, beta-axis component ipn-is that n active current ipn-is that n meritorious DC component iqn-is that n reactive current iqn-is n idle DC component ian, i β n-is a of nth harmonic electric current, beta-axis component ian, ibn icn-is that n three phase harmonic electric current 6-is that 5 instruction current computing circuit 7-are that 7 instruction current computing circuit 8-are that 11 instruction current computing circuit 9-are 13 instruction current computing circuit ia ₅, ib ₅, ic ₅-be three-phase 5 subharmonic current ia ₇, ib ₇, ic ₇-be three-phase 7 subharmonic current ia ₁₁, ib ₁₁, ic ₁₁-be three-phase 11 subharmonic current ia ₁₃, ib ₁₃, ic ₁₃-be three-phase 13 subharmonic currents

Embodiment

With reference to Fig. 1, present embodiment is by current converter circuit 1, instruction current computing circuit 2, and offset current generation circuit 4, automatic amplitude limiter circuit 3, demonstration and operation control 5 are formed.Described current converter circuit 1 be with Current Transformer Secondary measure harmonic current detection signal * ih, each electrical energy parameter amount, each guard signal be transformed into the load current signal that active electric filter device is suitable for through current/voltage and digital-to-analog.The effect of described offset current generation circuit 4 is the offset currents that produce reality according to the offset current command signal of instruction current computing circuit output.Offset current generation circuit 4 is made of current tracking control circuit, drive circuit and main circuit three parts.Main circuit is to adopt the PWM current transformer, and the PWM current transformer is that voltage-type is made up of with three pole reactor Lb three-phase IGBT Intelligent Power Module and the capacitor C and the filtering that are attached thereto.The central role of described instruction current computing circuit 2 is to detect the harmonic current of target compensation, therefore is also referred to as harmonic current detection circuit.Automatically amplitude limiter circuit 3 is to be made of adjustable resistance two ends in the instruction current computing circuit and the voltage stabilizing didoe that connect two reversal connections, is the output signal voltage amplitude that limits the instruction current computing circuit.With reference to Fig. 2, instruction current computing circuit 2 is that n frequency multiplier circuit N connects phase-locked loop, phase-locked loop pll by just, cosine generation circuit sin, cos the one 2 phase/2 phase coordinates converter Cn, the 22 phase/2 phase coordinates converter C that connect respectively ^-1N, 3 phases/2 phase coordinates converter C ₃₂By the one 2 phase/2 phase coordinates converter Cn and meet the first low pass filter LPF, the second low pass filter LPF; The 22 phase/2 phase coordinates converter C ^-1N connects 2 phases/3 phase coordinates converter C ₂₃With n frequency multiplier circuit N, phase-locked loop and one just, cosine generation circuit obtains the cosine signal comn ω t and the sinusoidal signal sinn ω t of supply voltage ea correspondence.Cosine signal comn ω t and sinusoidal signal sinn ω t signal import the 1 mutually/2 phase coordinates converter Cn form the rotating coordinate transformation matrix, the expression formula of Cn is as follows:

$\mathrm{Cn}=\left[\begin{array}{cc}\cos \left(\mathrm{n\ωt}\right)& -\sin \left(\mathrm{n\ωt}\right)\\ \sin \left(\mathrm{n\ωt}\right)& \cos \left(\mathrm{n\ωt}\right)\end{array}\right]$

N time active current ipn draws meritorious DC component ipn, i.e. harmonic current n time through the first low pass filter LPF filtering; It is the nth harmonic electric current that n reactive current iqn draws n idle DC component iqn through the second low pass filter LPF filtering, by n meritorious harmonic current ipn and n idle harmonic component iqn by 2 phase coordinates converter C mutually/3 ₂₃Can calculate n three phase harmonic current i an, ibn, icn.

Described n frequency multiplier circuit N is integrated V/f of TC9400 monolithic and the f/V convertor ic that adopts Toshiba Corp, and it is that supply voltage ea is converted to frequency signal, and frequency signal amplifies n doubly.The utility model is the instruction current computing circuit of setting up at different subharmonic, by making up the harmonic signal of each time detection, realizes the alternative control to harmonic wave.With reference to Fig. 3, three-phase current signal ia, ib, ic import 8,13 instruction current computing circuits 9 of 7,11 instruction current computing circuits of 6,7 instruction current computing circuits of 5 instruction current computing circuits respectively; The three-phase 5 subharmonic current ia that 8,13 instruction current computing circuits 8 of 7,11 instruction current computing circuits of 6,7 instruction current computing circuits of 5 instruction current computing circuits are exported respectively ₅, ib ₅, ic ₅, three-phase 7 subharmonic current ia ₇, ib ₇, ic ₇, three-phase 11 subharmonic current ia ₁₁, ib ₁₁, ic ₁₁, three-phase 13 subharmonic current ia ₁₃, ib ₁₃, ic ₁₃For example, only get 5 times, 11 rd harmonic signal, can realize that active electric filter device is only to 5 times, the filtering of 11 subharmonic, perhaps with total current and fundamental current, 5 times, 11 subharmonic currents are subtracted each other, and can realize that the active power filtering dress is to 5 times, the outer all filterings of other harmonic wave of 11 subharmonic.

Claims (1)

1, a kind of active electric filter device, it is to comprise current converter circuit, instruction current computing circuit, offset current generation circuit, automatically amplitude limiter circuit, demonstration and operation control; The instruction current computing circuit comprise that phase-locked loop connects just, cosine generation circuit the one 2 phase/2 phase coordinates converters, the 22 phase/2 phase coordinates converters that connect respectively, 3 phases/2 phase coordinates converters are by the one 2 phase/2 phase coordinates converters and connect first low pass filter, second low pass filter; The 22 phase/2 phase coordinates converters connect 2 phases/3 phase coordinates converters, it is characterized in that: also be included in the n frequency multiplier circuit (N) that phase-locked loop connects previously, by the n frequency multiplier circuit supply voltage (ea) is converted to frequency signal, frequency signal amplifies n doubly, obtains the nth harmonic electric current at last.

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