CN203151095U - Transformerless hybrid active power filter - Google Patents

Abstract

The utility model discloses a transformerless hybrid active power filter, comprising a double-tuned passive filter and a diode-clamped active power filter. The diode-clamped active power filter is a three-level inverter. The double-tuned passive filter comprises three passive filter branches connected with A, B, and C phase of a power grid. Each passive filter branch comprises an injection capacitor (C1), a voltage-dividing capacitor (C2), a shunt capacitor (C3), a first inductance (L1) and a second inductance (L2). Injection points of the three passive filter branches are respectively connected with three terminals on an AC side of the three-level inverter through three output inductances (L). The transformerless hybrid active power filter is characterized by low PPF cost, and excellent APF filter performance and dynamic performance, and the power filter is easy to implement and filtering effect is good.

Description

A kind of transless type hybrid active electric filter

Technical field

The utility model belongs to that harmonic wave in the electric power system suppresses and the technical field of reactive power compensation, relates to a kind of transless type hybrid active electric filter.

Background technology

At present, the extensive use of power electronic equipment has brought voltage flicker to electrical network in the electric power system, no-power vacancy, power quality problems such as harmonic pollution.For preventing that the major accident that above-mentioned power quality problem causes from taking place, and therefore need install advanced harmonic wave and suppress and reactive power compensator in power distribution network.

Can solve the problems referred to above by passive filter or Active Power Filter-APF.Passive power filter is the resonance characteristic of utilizing inductance, capacity cell, forms the Low ESR branch road of harmonic wave, has advantages such as cost is low, technology maturation, but exists filtering characteristic to rely on electrical network parameter, easily deficiencies such as imbalance and resonance; Active Power Filter-APF is that a kind of dynamic harmonic wave suppresses and reactive power compensator, can overcome the shortcoming of passive power filter, but cost of investment is too high, is difficult to realize large-scale promotion and application.

Figure 11 is traditional double-tuned filter, and it is applied to the passive filtering occasion.Traditional double tuned filter fundamental voltage is born by capacitor, can't directly apply among the hybrid active electric filter.

In order to solve the development of electrical network power quality problem, propelling harmonic wave inhibition technology, Chinese scholars has been carried out the research of mixed active electric power filter.Mixed active electric power filter is combined by suitable mode by passive current filter and Active Power Filter-APF, can realize the reasonable compromise of filtering performance and cost of investment.Wherein 1) injects the resonant mode mixed active electric power filter, constitute injection branch by passive filter and first-harmonic resonance circuit, Active Power Filter-APF is connected to injection branch by coupling transformer, because the decanting point fundamental voltage is 0, Active Power Filter-APF can't absorb keeps the active power of self working, need additional designs lower pressure rectifier device to keep the direct voltage of Active Power Filter-APF, make the system configuration complexity, and volume is big, cost is high; 2) in the inductance capacitance Hybrid Type Series Active Power Filter topology, be connected into the public electric wire net Coupling point after voltage source inverter and filter inductance and the capacitances in series, reactive power compensation electric current and harmonic compensation current that system is whole all will be provided by Active Power Filter-APF, cause the Active Power Filter-APF rated current higher, the cost height, reliability is relatively poor; 3) in the injection mixed active power filter that inductance capacitance is formed, the passive leg that inductance capacitance is formed is for providing reactive power compensation, the reactive current Active Power Filter-APF of not flowing through, an Active Power Filter-APF compensation harmonic electric current, though the rated current of Active Power Filter-APF descends to some extent, but because 5 times, the 7 times bigger harmonic waves of equal size are afforded redress by Active Power Filter-APF, the cost of system and capacity are still higher.

Therefore, be necessary to design a kind of novel electric-power filter.

The utility model content

Technical problem to be solved in the utility model provides a kind of transless type hybrid active electric filter, this transless type hybrid active electric filter has filtering performance and the dynamic property excellent characteristics of the low and APF of PPF cost simultaneously, easy to implement, filter effect is good.

The technical solution of utility model is as follows:

A kind of transless type hybrid active electric filter comprises double tunning passive filter and diode clamp type active filter;

Described diode clamp type active filter is three-level inverter;

The double tunning passive filter comprises 3 passive filtering branch roads that link to each other respectively mutually with A, B, the C of electrical network; Each bar passive filtering branch road comprises the injection capacitor C ₁, the dividing potential drop capacitor C ₂, shunt capacitance C ₃, first inductance L ₁With second inductance L ₂

Inject capacitor C ₁A termination electrical network, inject capacitor C ₁The other end successively through the dividing potential drop capacitor C ₂With parallel branch ground connection; The structure of parallel branch is: shunt capacitance C ₃With second inductance L ₂After the series connection again with first inductance L ₁In parallel;

Article 3, the dividing point of passive filtering branch road is respectively by three outputting inductance L _fThree terminals that exchange side with three-level inverter link to each other respectively; Described dividing point refers to inject capacitor C in the passive filtering branch road ₁With the dividing potential drop capacitor C ₂Tie point.

Described three-level inverter comprises 3 brachium pontis and 2 dc bus capacitor (C _Dc1, C _Dc2, and C _Dc1=C _Dc2), the DC side series equivalent capacitance is C _Dc1/ 2,2 dc bus capacitor series connection backs are in parallel with 3 brachium pontis;

Each brachium pontis is made up of 4 switching tubes and 2 clamp diodes; Wherein, last brachium pontis and following brachium pontis each form (the C utmost point that the E utmost point that is specially 1 switching tube is connected another switching tube) by 2 switching tubes; In each brachium pontis, 2 clamp diodes are first clamp diode and second clamp diode, and the positive pole of first clamp diode is connected with the negative pole of the two or two clamp diode; The negative pole of first clamp diode connects the tie point of 2 switching tubes of brachium pontis; The positive pole of second clamp diode connects down the tie point of 2 switching tubes of brachium pontis;

The mid point of three brachium pontis respectively with described three outputting inductance L _fLink to each other, the mid point of described brachium pontis refers to the tie point of brachium pontis and following brachium pontis;

The mid point of three brachium pontis, three clamper mid points and the equal short circuit of dc bus capacitor mid point; Described clamper mid point refers to the tie point of 2 clamp diodes of each brachium pontis correspondence; Described dc bus capacitor mid point refers to the serial connection point of 2 dc bus capacitors.

Inject capacitor C ₁, the dividing potential drop capacitor C ₂, shunt capacitance C ₃, first inductance L ₁With second inductance L ₂Value variously determined by following respectively:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_1=\frac{Q}{{\mathrm{\&omega;}}_0{U}_{\mathrm{Pcc}}(U_{\mathrm{Pcc}}-U_r)}\\ {\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=\frac{Q}{{\mathrm{\&omega;}}_0{U}_{\mathrm{Pcc}}{U}_r}\end{array}\right.$

Wherein, ω ₀Be the first-harmonic angular frequency, Q is reactive power compensation capacity (being determined by loading condition), U _PCCAnd U _rBe respectively line voltage effective value and decanting point voltage effective value; (its instantaneous value obtains by voltage measuring transformer; The effective value of these two voltages is known when design, must know the effective value of line voltage when system designs, and the effective value of decanting point voltage has determined the rated voltage of active filter, is to determine according to the design object of Active Power Filter-APF.Need the instantaneous value of these two voltages in the control, obtained by voltage measuring transformer) $\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1=\frac{{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="X"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">X</figure-callout>}}}^2}{{{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2\mathrm{<figure-callout\; id="2"\; label="C\; L"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}& \\ L_{}{}_2=\frac{1}{{{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1{\mathrm{CC}}_3}\\ {\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_3=\frac{{{\mathrm{\&omega;}}_5}^2+{{\mathrm{\&omega;}}_7}^2}{{{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2}-\frac{1}{{{\mathrm{\&omega;}}_X}^2{L}_1}-C\end{array}\right.;$ Wherein, ω ₅And ω ₇Be respectively 5,7 resonance angular frequencies;

[passive leg parallel resonance frequency point ω _XBetween 5 times, 7 subfrequencies, i.e. ω ₅≤ ω _X≤ ω ₇, ω _XSpan is arranged, as long as L1, L2, the value of C3 makes ω _XSatisfying this scope and get final product, is L1 therefore, L2, and the C3 value decides ω _X】

[filter inductance L _fDuring design, need to consider transient current follow-up control and ripple current size, i.e. filter inductance L _fDesign is satisfied:

In the formula, E _mBe the amplitude of Active Power Filter-APF decanting point phase voltage,

Be the minimum subharmonic current component of Active Power Filter-APF output, the utility model is 11 subharmonic current effective value, i.e. n _Min=11, the direct voltage set point

Switch periods is Be the control frequency of Active Power Filter-APF power switch, ripple current maximum Δ i _MaxGenerally get output current 5%.] [in order to reduce the dc voltage fluctuation, dc bus capacitor must have the certain capacity requirement.When dc voltage one timing, capacitance is more little, more is conducive to the rapid track and control of direct voltage; And capacitance is more big, more is conducive to the dc voltage fluctuation is limited in the reasonable range.Therefore, the equivalent capacitance value of dc bus capacitor is

(perhaps

) satisfy:

$\frac{\mathrm{\&Delta;}{P}_{\max }{t}_{\max }}{{V_{\mathrm{DC}}}^{*}\mathrm{\&Delta;}{V}_{\mathrm{DC}\max }}\&le;\frac{1}{2}{\mathrm{<figure-callout\; id="1"\; label="C\; dc"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_{\mathrm{dc}}=\frac{1}{2}{\mathrm{<figure-callout\; id="2"\; label="C\; dc"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_{\mathrm{dc}}\&le;\frac{t_r^{*}}{R_d\ln \frac{1.2{V_{\mathrm{DC}}}^{*}-{\mathrm{<figure-callout\; id="0"\; label="V\; DC"\; filenames="HDA00002709486100013.png,HDA00002709486100021.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{DC}}}{0.2{V_{\mathrm{DC}}}^{*}}},$ In the formula,

For direct voltage from the uncontrollable direct voltage V of three-phase _DC0To given voltage V _DC ^*Rise time, t _MaxBe the maximal regulated time of voltage control link, Δ V _DCmaxBe the maximum ripple value of direct voltage, the general requirement is 5%V _DC ^*, R _dBe the DC side equivalent resistance, Δ P _MaxBe the maximum variable quantity of active leg loss power.】

A kind of implementation method of transless type hybrid active electric filter is characterized in that, adopts aforesaid transless type to mix the topological structure of three level active power filters and injects capacitor C ₁, the dividing potential drop capacitor C ₂, shunt capacitance C ₃, first inductance L ₁With second inductance L ₂Parameter choose;

The double tunning passive filter is used for filtering 5 times and 7 subharmonic;

No-power vacancy is by injecting capacitor C ₁With the dividing potential drop capacitor C ₂Compensate jointly;

Adopt the dividing potential drop capacitor C ₂Realize that dividing potential drop makes diode clamp type active filter only bear the part fundamental voltage, thereby realize harmonic compensation and reactive power compensation.

The control method of aforesaid transless type hybrid active electric filter adopts the two closed-loop control strategies of voltage-to-current to implement control;

The current inner loop control of hybrid active electric filter: sampling load current i _LEnter slip DFT harmonic wave and detect, detect higher harmonic current i more than 11 times _H(comprising 11,13,17,19 subharmonic current signals), i _HReference signal as active part output harmonic wave electric current in the mixed active electric power filter; For the dc voltage of keeping active part is steady state value, active part is kept direct voltage by absorption, fundamental reactive current signal delta i _qControl signal for the output of direct voltage control outer shroud; Fundamental reactive current signal delta i _qWith harmonic current reference signal i _HSuperposition value is as the reference signal of current inner loop, and reference signal and output current ic do difference and enter the ratio resonant controller; Described ratio resonant controller comprises proportional controller (the control parameter is Kp), and 11 times, 13 times, 17 times, 19 times resonant controller;

The control of ratio resonance is followed the tracks of control, the w in the controller to the no steady-state error that the each harmonic electric current carries out ₁₁-w ₁₉The angular frequency of difference 11-19 subharmonic, [in the example, Kp=2.2, k _I11=k _I13=K _I17=K _I19=0.002] the reactive current conditioning signal Δ i of outer voltage _qDifference by actual voltage value and set-point multiply by cos (ω through pi regulator ₀The t-pi/2) (hysteresis fundamental positive sequence voltage 90 degree) obtain; The output signal of ratio resonant controller and decanting point electric voltage feed forward signal Ur[are the voltage at dc bus capacitor tie point place, the voltage of Lf right-hand member among Fig. 1.] stack is as always entering pwm signal generation link with reference to signal, the generation pwm signal is controlled the IGBT break-make.

[the ratio resonant controller realizes the approximates infinity gain in some fixed frequencies (resonance frequency), and infinite attenuation outside this fixed frequency can make with resonance frequency w to have same frequency sinusoidal signal realization zero steady-state error tracking like this.Because it has selectivity to harmonic frequency, can implement accurate control to a certain frequency signal, thus can be to high order harmonic component frequency division controls such as 11,13,17,19.Ratio resonant controller among Fig. 5 is proportional controller (the control parameter is Kp), and the stack of 11 times, 13 times, 17 times, 19 times resonant controller.】

Described Voltage loop controller is the PI controller, being given as of Voltage loop Be fed back to V _DC, i.e. the dc voltage of diode clamp type active filter] and [in the example, the direct voltage reference value is got

].

Beneficial effect:

Transless type hybrid active electric filter of the present utility model, utilize novel double-tuned filter, one side bucking-out system reactive power and 5 times, 7 subharmonic currents, on the other hand, and make Active Power Filter-APF only bear less fundamental voltage and do not need extra electric supply installation, Active Power Filter-APF adopts three-level inverter, make the performance of Active Power Filter-APF improve, volume reduces, and voltage, the electric current of active part reduce by norm, and cost significantly reduces.

The filtering performance and the dynamic property excellent characteristics that have the low and Active Power Filter-APF of passive current filter cost simultaneously, wherein, diode-clamped three level active power filters only are used for the higher harmonic current more than 11 times, cracking capacitance partial pressure by modified model double-tuned filter circuit makes Active Power Filter-APF bear lower fundamental voltage, compares simple Active Power Filter-APF capacity and significantly reduces; Active part adopts diode-clamped three level active power filters, has reduced near the harmonic wave of switching frequency, and switch increases simultaneously, also can reduce capacity requirement; This device double-tuned filter is cracked into two with electric capacity on traditional basis, because the part in parallel of passive filter is almost nil to the impedance of first-harmonic, harmonic wave is presented high impedance, so no-power vacancy compensates [electric capacity after the cracking here is c1 and c2] by two electric capacity of cracking, can realize that dividing potential drop makes diode-clamped three level active power filters bear the fraction fundamental voltage by electric capacity after the decanting point simultaneously, make harmonic compensation effect and reactive power compensation reach optimum; The harmonic wave that the utility model is particularly suitable for the big capacity of low pressure or mesohigh suppresses occasion.

Therefore, for reducing the capacity of Active Power Filter-APF significantly, the utility model proposes a kind of novel mixed active electric power filter topological structure, the rated voltage of Active Power Filter-APF is far smaller than system voltage in this structure, output current only comprises higher harmonic current more than 11 times, and rated current also reduces greatly.Simultaneously, because Active Power Filter-APF decanting point voltage is suitable, it can absorb suitable power from decanting point and keep self normal operation, and need not the additional designs DC power supply apparatus.

Improvement double-tuned filter of the present utility model not only can be finished 5,7 filtering, can also realize reactive power compensation, offer the lower fundamental voltage of active part, makes its operate as normal.

Description of drawings

Fig. 1 is the circuit theory diagrams of pouring-in mixing three level active power filters of the utility model transless type;

Fig. 2 is the humorous wave zone one phase equivalent circuit figure of pouring-in mixing three level active power filters of the utility model transless type;

Fig. 3 is the passive circuit Bode diagram of pouring-in mixing three level active power filters of the utility model transless type;

Fig. 4 is part impedance Bode diagram in parallel;

Fig. 5 is the single-phase equivalent control block diagram of Active Power Filter-APF in the utility model;

Fig. 6 is the experiment block diagram of pouring-in mixing three level active power filters of the utility model transless type;

Fig. 7 is load current waveform and fft analysis in the emulation experiment of pouring-in mixing three level active power filters of the utility model transless type;

Fig. 8 is that passive circuit drops into back source current waveform and fft analysis in the emulation experiment of pouring-in mixing three level active power filters of the utility model transless type;

Fig. 9 is source current waveform and the fft analysis after the passive circuit of pouring-in mixing three level active power filters of transless type in the emulation experiment and active filter all put into operation;

Figure 10 is that the output voltage waveforms of the Active Power Filter-APF of pouring-in mixing three level active power filters of transless type in the emulation experiment (is schemed a) and output current wave (figure b).

Figure 11 is traditional double tuned filter topological structure.

Embodiment

Below with reference to the drawings and specific embodiments the utility model is described in further details:

Embodiment 1:

The utility model proposes a kind of transless type mixed active electric power filter topological structure, as shown in Figure 1, pouring-in mixing three level active power filters of transless type are made of improved double tunning passive power filter and diode clamp type three level active power filters.Wherein novel double tunning passive power filter is by capacitor C ₁, C ₂, C ₃, L ₁, L ₂Form, Active Power Filter-APF is connected in parallel on the injection capacitor C ₁Back point.Active Power Filter-APF props up route filter inductance L _f, power model, dc capacitor C _Dc1And C _Dc2Constitute.Wherein power model is a tri-level inversion module, by IGBTQ ₁～Q ₄, Q ' ₁～Q ' ₄, Q " ₁～Q " ₄, clamp diode D ₁～D ₂, D ' ₁～D ' ₂, D " ₁～D " ₂Constitute.

The passive leg capacitor C ₁And C ₂Realization system reactive power compensation, and form bleeder circuit, capacitor C ₁Bear most of fundamental voltage, capacitor C ₂Bear the fraction fundamental voltage; Simultaneously, passive leg goes out to present Low ESR at 5 times and 7 subharmonic, and namely 5 times and 7 primary currents suppress by injection circuit.The voltage that Active Power Filter-APF bears is capacitor C ₁With capacitor C ₂Fraction fundamental voltage after the dividing potential drop, therefore, reduced the rated voltage of Active Power Filter-APF on the one hand, guaranteed that on the other hand Active Power Filter-APF can absorb suitable fundamental active power from electrical network, keep normal operation, and need not the additional designs power supply circuits.Because passive circuit is realized reactive power compensation, 5 times and the inhibition of 7 subharmonic, Active Power Filter-APF realizes 11,13,17,19, etc. the inhibition of higher harmonic current, the low-order harmonic electric current does not flow into Active Power Filter-APF, only keep dc-voltage balance by a small amount of reactive current, so the rated current of Active Power Filter-APF reduces greatly also.

Fig. 2 is humorous wave zone one phase equivalent circuit of the present utility model.E among Fig. 2 _ShBe the harmonic component of line voltage, L _sBe power network line equivalent inductance, i _ShBe the harmonic current of electrical network, i _C2hBe the harmonic current that the active leg of mixed active electric power filter is exported, i _ChOutput current for mixed active electric power filter.If X ⁿ() represents the impedance that each passive component presents for nth harmonic, after the mixed active electric power filter compensation, and the nth harmonic component of power network current For

$i_{\mathrm{sh}}^n=\frac{e_{\mathrm{sh}}^n+i_L^n[X^n\left(C_1\right)+X^n\left(R_R\right)]-i_{C2h}^n{X}^n\left(R_R\right)}{X^n\left(L_s\right)+X^n\left(C_1\right)+X^n\left(R_R\right)}---\left(1\right)$

In the formula, X ⁿ(R _R) be below the decanting point, i.e. C ₂, C ₃, L ₁, L ₂The impedance that branch road presents nth harmonic.

According to formula (1), the harmonic component e of line voltage _ShAlso can produce harmonic current.Yet the harmonic voltage of electrical network is very little usually, therefore can ignore the harmonic current that harmonic voltage causes.But for avoiding mixed active electric power filter to amplify the voltage harmonic of electrical network, must make

|X ⁿ(L _s)+X ⁿ(C ₁)+X ⁿ(R _LR)|＞δ (2)

In the formula, N _Max〉=n 〉=N _Min, δ is enough little positive number, N _Max, N _MinFor harmonic wave suppresses the desired minimum harmonic number of times of occasion and higher harmonics number of times.

In the mixed active electric power main circuit design, formula (2) as constraints, can be prevented system impedance, resonant circuit and injection electric capacity generation series parallel resonance.

Order

$\left|G_{S1}^n\left(\mathrm{\&omega;}\right)\right|=\left|\frac{X^n\left(C_1\right)+X^n\left(R_R\right)}{X^n\left(L_s\right)+X^n\left(C_1\right)+X^n\left(R_R\right)}\right|$

For 5 times in the load current and 7 subharmonic current components, because passive leg integral body presents the double-tuned filter characteristic, therefore | X ⁿ(C ₁)+X ⁿ(R _R) | therefore be almost 0,5 times and 7 times are by the passive leg filtering.

For the higher harmonic components of load current, if control by the current inner loop of mixed active electric power filter active leg, make the nth harmonic electric current of its output current

Equal reference current

And

Then

$i_{C2h}^n=i_L^n---\left(3\right)$

With formula (3) substitution formula (1), have

$i_{\mathrm{sh}}^n=\frac{e_s^n+i_L^n{X}^n\left(C_1\right)}{X^n\left(L_s\right)+X^n\left(C_1\right)+X^n\left(R_R\right)}---\left(4\right)$

$\left|G_{S2}^n\left(\mathrm{\&omega;}\right)\right|=\left|\frac{X^n\left(C_1\right)}{X^n\left(L_s\right)+X^n\left(C_1\right)+X^n\left(R_R\right)}\right|---\left(5\right)$

Because

In the utility model, the higher harmonic current more than 11 times of the tracking load of mixed active electric power filter, therefore, the higher harmonic components more than 11 times of power network current will be inhibited.

To sum up, device of the present utility model by double tunning passive power filter and 3 flat Active Power Filter-APFs of diode clamp type by above-mentioned connected mode and control method, not only can promote the harmonic compensation effect, satisfy idle compensation requirement simultaneously, and the capacity requirement of reduction active part, make it can be widely used in the occasion of low-pressure high-power or mesohigh.

The design feature of this transless type hybrid active electric filter is: the passive leg setting is by C ₁, C ₂, C ₃, L ₁, L ₂Two resonance points of the double-tuned filter that constitutes are 5 times and 7 subharmonic, are used for filtering 5,7 subharmonic, C ₁And C ₂Between be the decanting point of Active Power Filter-APF, active part is responsible for compensating the high order harmonic component beyond 5,7 times, injects capacitor C ₁Bear most of fundamental voltage, make active part bear very little fundamental voltage and keep operate as normal.Between 250-350HZ, this moment, part impedance of fundamental frequency in parallel was almost 0 by the parallel resonance frequency of the characteristic parallel branch of double-tuned filter.

The modulus of impedance of passive leg is

$\left|X_{\mathrm{PC}}\left(\mathrm{\&omega;}\right)\right|=|-\frac{1}{\mathrm{\&omega;C}}+\frac{{\mathrm{\&omega;}}^3{L}_1{L}_2{C}_3-\mathrm{\&omega;}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}{{\mathrm{\&omega;}}^2{C}_3({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2)-1}|---\left(6\right)$

Because near passive leg resonance 5,7 times, then the impedance of corresponding 5,7 secondary frequencies is 0, has

$\left\{\begin{array}{c}{{\mathrm{\&omega;}}_5}^2+{{\mathrm{\&omega;}}_7}^2=\frac{L_2{\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_3+L_1{\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_3+L_{1}C}{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_2{\mathrm{<figure-callout\; id="3"\; label="CC"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">CC</figure-callout>}}_3}\\ {{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2=\frac{1}{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_2{\mathrm{CC}}_3}\end{array}\right.---\left(7\right)$

Wherein $C=\frac{C_1{C}_2}{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}.$

Fig. 3 is the frequency impedance characteristic curve of passive leg, sees that as seen the impedance for 5,7 passive legs is 0.

L ₁And C ₃, L ₂Constitute parallel branch, its modulus of impedance is

$\left|X_{\mathrm{para}}\left(\mathrm{\&omega;}\right)\right|=\left|\frac{{{\mathrm{\&omega;}}_X}^3{L}_1{L}_2{C}_3-{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="1"\; label="X\; L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">X</figure-callout>}}{L}_{}{}_1}{{{\mathrm{\&omega;}}_X}^2{C}_3({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2)-1}\right|---\left(8\right)$

The impedance of parallel branch as shown in Figure 4, as seen, the impedance of fundamental frequency of part in parallel can be realized the dividing potential drop of two cracking electric capacity near 0.

Passive leg parallel resonance frequency point ω _XFor

${\mathrm{\&omega;}}_X=\sqrt{1/C_3({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2)}---\left(9\right)$

Known passive leg parallel resonance frequency point ω by double tunning passive power filter intrinsic property _XBetween 5 times, 7 subfrequencies, i.e. ω ₅≤ ω _X≤ ω ₇

According to formula 8, L ₁, R ₁And C ₃, L ₂, R ₂Constitute parallel impedance Z _Para(ω) present Low ESR at the fundamental frequency point, so fundamental voltage there is all the electric capacity of passive leg to bear.If mixed active electric power filter access point phase voltage first-harmonic effective value is U _Pcc, Active Power Filter-APF access point voltage effective value is U _r, the reactive power compensation capacity is Q, can determine capacitor C ₁And C ₂For

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_1=\frac{Q}{{\mathrm{\&omega;}}_0{U}_{\mathrm{Pcc}}(U_{\mathrm{Pcc}}-U_r)}\\ {\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=\frac{Q}{{\mathrm{\&omega;}}_0{U}_{\mathrm{Pcc}}{U}_r}\end{array}\right.---\left(10\right)$

According to Fig. 1, the passive part in parallel with Active Power Filter-APF also is a double-tuned filter, and as calculated, its resonance point is a little less than 5,7 times, and therefore the high order frequency harmonics for Active Power Filter-APF output presents higher resistance.

According to above analysis, parameter determines that rule is as follows:

1) by system load no-power vacancy Q, system voltage UPCC and decanting point voltage U _RDetermine C ₁And C ₂:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_1=\frac{Q}{{\mathrm{\&omega;}}_0{U}_{\mathrm{Pcc}}(U_{\mathrm{Pcc}}-U_r)}\\ {\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=\frac{Q}{{\mathrm{\&omega;}}_0{U}_{\mathrm{Pcc}}{U}_r}\end{array}\right.---\left(11\right)$

Wherein, ω ₀Be the first-harmonic angular frequency, Q is determined by loading condition, U _PCCAnd U _RObtained by voltage measuring transformer.

2) L ₁, L ₂, C ₃The impedance expression of parallel branch:

$\left|X_{\mathrm{para}}\left(\mathrm{\&omega;}\right)\right|=\left|\frac{{{\mathrm{\&omega;}}_X}^3{L}_1{L}_2{C}_3-{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="1"\; label="X\; L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">X</figure-callout>}}{L}_{}{}_1}{{{\mathrm{\&omega;}}_X}^2{C}_3({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2)-1}\right|---\left(12\right)$

When following formula is 0, have ω wherein _XIt is the parallel resonance angular frequency.

3) passive double-tuned filter has at 5,7 resonance:

$\left\{\begin{array}{c}{{\mathrm{\&omega;}}_5}^2+{{\mathrm{\&omega;}}_7}^2=\frac{L_2{\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_3+L_1{\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_3+L_{1}C}{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_2{\mathrm{<figure-callout\; id="3"\; label="CC"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">CC</figure-callout>}}_3}\\ {{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2=\frac{1}{L_1{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_2{\mathrm{CC}}_3}\end{array}\right.---\left(13\right)$

Wherein

ω ₅And ω ₇Be respectively 5,7 resonance angular frequencies.

Can be determined by above formula:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1=\frac{{{\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="2"\; label="X"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">X</figure-callout>}}}^2}{{{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2\mathrm{<figure-callout\; id="2"\; label="C\; L"\; filenames="HDA00002709486100032.png,HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}& \\ L_{}{}_2=\frac{1}{{{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002709486100021.png,HDA00002709486100041.png"\; state="\{\{state\}\}">L</figure-callout>}}_1{\mathrm{CC}}_3}\\ {\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="HDA00002709486100041.png"\; state="\{\{state\}\}">C</figure-callout>}}_3=\frac{{{\mathrm{\&omega;}}_5}^2+{{\mathrm{\&omega;}}_7}^2}{{{\mathrm{\&omega;}}_5}^2{{\mathrm{\&omega;}}_7}^2}-\frac{1}{{{\mathrm{\&omega;}}_X}^2{L}_1}-C\end{array}\right.---\left(14\right)$

Utility model is double-tuned filter, and 5,7 times resonance angular frequency all needs ω _XAsk for reference to formula (9).

A kind of transless type mixes three level active power filters, comprising: double tunning passive power filter and diode-clamped three level active power filters; The double tunning passive power filter is connected in parallel in the electrical network, and overall resonance frequency is located at 5,7 times, and parallel resonance frequency is between 5,7 times, and the reactive power compensation and the harmonic wave that are used for electrical network suppress.

Diode-clamped three level active power filters and behind the injection electric capacity of double tunning passive power filter point, be mainly used in compensating 11,13 times, 17,19 times harmonic wave.

The single-phase equivalent control block diagram of three level active power filters as shown in Figure 5.The harmonic detecting method that the utility model three level active inverters adopt slip DFT detects one by one to higher harmonic currents such as 11,13,17,19, avoided the imperfection based on the detection of instantaneous reactive power theory single harmonic component, it is more accurate to make that single harmonic component detects, and makes Active Power Filter-APF no longer export 5,7 inferior low-order harmonics.Be directed to the control of single harmonic component detection and direct voltage, the utility model has adopted the control of electric current and voltage dicyclo.Be directed to harmonic wave and detect the algorithm that adopts slip DFT, current inner loop adopts ratio resonance control algolithm, controls at each harmonic wave, realizes zero steady-state error.

Because injection branch capacitor C ₁Existence, the control of the utility model outer voltage adopts the PI control of reactive current to stablize dc voltage.The PI controller parameter of Voltage loop is among Fig. 5: Kp=80, Ki=4000.

I among Fig. 5 _LThe load current of representative sampling, ic is the output current of hybrid active filter, Vf* is the reference voltage signal that enters PWM control.

The current inner loop control of the hybrid active electric filter in the utility model is by sampling load current i _LEnter slip DFT harmonic wave and detect, detect higher harmonic current i more than 11 times _H, the conditioning signal Δ i of back and outer voltage _qStack is as the reference signal of current inner loop controller, reference signal and output current i _cDo difference and enter the ratio resonant controller.The described ratio resonant controller of this patent is proportional controller (the control parameter is Kp), and the stack of 11 times, 13 times, 17 times, 19 times resonant controller.The control of ratio resonance can realize the zero steady-state error tracking control of each harmonic, and the w11-w19 in the controller is 11-19 subharmonic angular frequency respectively, and the controller relevant parameter is: Kp=2.2, ki11=ki13=Ki17=Ki19=0.002.The reactive current conditioning signal Δ i of outer voltage _qMultiply by cos (ω t-pi/2) (phase signals of hysteresis fundamental positive sequence voltage 90 degree) by differing from of actual voltage value and direct voltage set-point through pi regulator obtains.Final control output signal and decanting point electric voltage feed forward signal Ur stack generate link as always entering pwm signal with reference to signal, generate pwm signal control IGBT break-make.

The analysis showed that more than mixed active electric power filter shown in the utility model has following characteristics: 1) avoided the coupling transformer of conventional hybrid type Active Power Filter-APF to the influence of system cost, performance and volume; 2) the modified model double-tuned filter can compensating power, filtering 5 and and 7 subharmonic, Active Power Filter-APF only need compensate the low content harmonic current more than 11 times, has lowered the rated current of Active Power Filter-APF greatly; 3) by the cracking capacitance partial pressure of double-tuned filter, make Active Power Filter-APF advance to bear less fundamental voltage, reduced the rated voltage of Active Power Filter-APF; 4) Active Power Filter-APF still can absorption portion power, keeps self normal operation, avoids the DC power supply apparatus of additional designs Active Power Filter-APF.

For correctness and the validity of checking transless mixed active electric power filter, build emulation experiment platform as shown in Figure 6.Among Fig. 6, testing used load is thyristor rectifier load and the resistance sense reactive load of three-phase three-wire system 380V/50Hz, and load current comprises reactive power electric current and 5 times, 7 times, 11 times, 13 times and 17 inferior harmonic currents.The topological sum control method of mixed active electric power filter as mentioned above, the passive component parameter of mixed active electric power filter is as described in Table 1.

Passive parameter and the value thereof of table 1 the utility model mixed active electric power filter

Fig. 7 is load current waveform and fft analysis in the emulation experiment, and load causes system to have the reactive power of 11kVar, and total harmonic current aberration rate of load current reaches 23.6%; Fig. 8 is after the modified model double-tuned filter drops into, power network current waveform and fft analysis, the modified model double-tuned filter has not only compensated the reactive power of system, and filtering 5 times and 7 subharmonic currents of load, behind the passive filtering, total harmonic current aberration rate of electrical network only is 7.8%, but can not satisfy the harmonic standard of power network current 5%; Fig. 9 is after the passive circuit of pouring-in mixing three level active power filters of transless type in the emulation experiment and active filter all put into operation, the current waveform of electrical network and fft analysis, as seen the high order harmonic component of electrical network is effectively suppressed by Active Power Filter-APF, total harmonic current aberration rate of compensation back electrical network is 3.6% only, satisfies the harmonic standard of electrical network; Figure 10 is output voltage and the output current wave of active leg in the mixed active electric power filter, and the voltage and current quota of visible Active Power Filter-APF is all very little.

The simulation experiment result shows that mixed active electric power filter reactive power compensation described in the utility model and harmonic suppression effect are good, and this topological structure system that makes has clear superiority aspect volume and the cost simultaneously.

Claims (3)

1. a transless type hybrid active electric filter is characterized in that, comprises double tunning passive filter and diode clamp type active filter;

Described diode clamp type active filter is three-level inverter;

The double tunning passive filter comprises 3 passive filtering branch roads that link to each other respectively mutually with A, B, the C of electrical network; Each bar passive filtering branch road comprises the injection capacitor C ₁, the dividing potential drop capacitor C ₂, shunt capacitance C ₃, first inductance L ₁With second inductance L ₂

Inject capacitor C ₁A termination electrical network, inject capacitor C ₁The other end successively through the dividing potential drop capacitor C ₂With parallel branch ground connection; The structure of parallel branch is: shunt capacitance C ₃With second inductance L ₂After the series connection again with first inductance L ₁In parallel;

Article 3, the dividing point of passive filtering branch road is respectively by three outputting inductance L _fThree terminals that exchange side with three-level inverter link to each other respectively; Described dividing point refers to inject capacitor C in the passive filtering branch road ₁With the dividing potential drop capacitor C ₂Tie point.

2. transless type hybrid active electric filter according to claim 1 is characterized in that, described three-level inverter comprises 3 brachium pontis and 2 dc bus capacitors, and the DC side series equivalent capacitance is C _Dc1/ 2,2 dc bus capacitor series connection backs are in parallel with 3 brachium pontis;

Each brachium pontis is made up of 4 switching tubes and 2 clamp diodes; Wherein, last brachium pontis and following brachium pontis respectively are made up of 2 switching tubes; In each brachium pontis, 2 clamp diodes are first clamp diode and second clamp diode, and the positive pole of first clamp diode is connected with the negative pole of the two or two clamp diode; The negative pole of first clamp diode connects the tie point of 2 switching tubes of brachium pontis; The positive pole of second clamp diode connects down the tie point of 2 switching tubes of brachium pontis;

The mid point of three brachium pontis respectively with described three outputting inductance L _fLink to each other, the mid point of described brachium pontis refers to the tie point of brachium pontis and following brachium pontis;

The mid point of three brachium pontis, three clamper mid points and the equal short circuit of dc bus capacitor mid point; Described clamper mid point refers to the tie point of 2 clamp diodes of each brachium pontis correspondence; Described dc bus capacitor mid point refers to the serial connection point of 2 dc bus capacitors.

3. transless type hybrid active electric filter according to claim 1 and 2 is characterized in that, injects capacitor C ₁, the dividing potential drop capacitor C ₂, shunt capacitance C ₃, first inductance L ₁With second inductance L ₂Value variously determined by following respectively:

Wherein, ω ₀Be the first-harmonic angular frequency, Q is the reactive power compensation capacity, U _PCCAnd U _rBe respectively line voltage effective value and decanting point voltage effective value;

Wherein, ω ₅And ω ₇Be respectively 5,7 resonance angular frequencies;

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