CN202602289U - Filter - Google Patents

Abstract

The utility model provides a filter. The filter comprises at least one group of filtering units, wherein the filtering unit comprises the following components of: a first reactor Li; a second reactor Lg which is connected in series with the first reactor; a damping resistor of which one end is in equivalent parallel connection with the second reactor Lg; and an equivalent capacitor of which one end is connected with the other end of the damping resistor, wherein the reactance value of the first reactor Li and the reactance value of the second reactor Lg are in the following ranges: 20f1<=1/2[pi]*[the square root of(Lg+Li)/LgLiC]<=fsw/2, 12%pu<=Li + Lg <= 5%pu, and 2<=Li/Lg<=3, wherein the C is the equivalent capacitor, the f1 is the output base wave frequency of an inverter, the fsw is the switching frequency of an insulated gate bipolar transistor IGBT in the inverter, and the pu is the voltage drop in phase voltage. The filter is advantageous in high conversion efficiency and small total harmonic distortion; and the filter can meet the administrative standards of various harmonic waves.

Description

Filter

Technical field

The utility model relates to a kind of filter, relates in particular to a kind of filter that is used for the novel energy electricity generation system.

Background technology

The exploitation of novel energy is global key subjects.Can not only progressively solve the lack of energy problem with novel energy generating (for example wind power generation and photovoltaic generation), also help to solve problem of environmental pollution.But the novel energy generating tends to inject a large amount of harmonic waves and reactive power to electrical network.For one of the solution problem, usually filter is connected a large amount of harmonic waves of elimination between electrical network and the inverter.Fig. 1 is used to explain the topological structure sketch map of a kind of novel energy generating convertor assembly system.As shown in the figure, convertor assembly 30 comprises inverter 305.The input of convertor assembly 30 connects novel energy generator 40, and the output of convertor assembly 30 connects three-phase alternating current electrical network 10.Three-phase alternating current electrical network 10 comprises U _a, U _bAnd U _cThree-phase.Filter 20 is connected between electrical network 10 and the convertor assembly 30, in order to reduce the harmonic wave quantity of input electrical network.Filter 20 comprises filter unit F _a, F _bAnd F _c, respectively with U _a, U _bAnd U _cBe connected.

In the generation of electricity by new energy field, line voltage is comparatively stable under normal conditions, and its harmonic content is less, so in this field, need choosing to current harmonics outstanding effect filter.In the existing Filter Design scheme, lack theoretical model and standard design method, usually, the relevant parameter in the filter need be according to engineer's experience repetition test decision.In addition, the energy conversion efficiency of existing filter is not high enough, and (hereinafter to be referred as THD) is inadequately little for total harmonic distortion, and system is reliable and stable inadequately, is easy to generate resonance phenomena.

The utility model content

The purpose of the utility model provides a kind of energy conversion efficiency up to 99%, and THD approximates 1%, meets the filter of each harmonic wave control standard.

The utility model provides a kind of filter that is used to filter inverter, comprising: at least one group of filter unit, said filter unit comprises: the first reactance L _iThe second reactance L that connects with said first reactance _gOne end and the said second reactance L _gThe damping resistance of equivalent parallel; And equivalent capacity, an end is connected with the other end of said damping resistance, and its other end is connected with the equivalent capacity of another group filter unit; Wherein, the said first reactance L _iReactance value and the said second reactance L _gReactance value in following scope:

$20{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">f</figure-callout>}}_1\&le;\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{L_g+L_i}{L_g{L}_{i}C}}\&le;f_{\mathrm{sw}}/2,$

12％pu≤L _i+L _g≤15％pu，

2≤L _i/L _g≤3，

Wherein, C is an equivalent capacity, f ₁Be inverter output fundamental frequency, f _SwBe the switching frequency of igbt in the inverter, pu is the phase voltage pressure drop.

The advantage of the utility model is:

1. the utlity model has very high energy conversion efficiency, power factor reaches 1, and efficient all can reach 99% under semi-load and nominal load, and because of generation of electricity by new energy efficient itself is not high, it is particularly important that the energy conversion efficiency of system becomes;

2. the utlity model has less current, voltage harmonic aberration rate, be about 1% at fully loaded THD down, the harmonic attenuation rate is high, meets harmonic wave control standards such as IEEE1547, IEEE519, VDE4105 and BDEW;

3. the utility model is taked the multiple-protection measure, like mistake, under-voltage, and overcurrent, short circuit, overheated, reactance supersaturation and precharge loop guarantee that thus reliable and secure operation of system stability and robustness are better;

4. the utility model avoids resonance phenomena to take place; And

5. the utility model is that the be incorporated into the power networks exploitation of filter of new forms of energy provides a cover novel and fruitful Theoretical Calculation and method for designing, and emulation and experimental result have all been verified its feasibility and correctness, have improved the accuracy and the reliability of development and Design.

Description of drawings

Hereinafter will be with clear and definite understandable mode through description of a preferred embodiment and combine accompanying drawing to come the above-mentioned characteristic of the utility model, technical characterictic, advantage and implementation thereof are further specified, wherein:

Fig. 1 is the topological structure sketch map of a kind of existing novel energy generating convertor assembly system;

Fig. 2 is the existing equivalent capacity that is the Star topology connection;

Fig. 3 exemplarily shows the topological structure sketch map of the convertor assembly system of an embodiment who comprises the utility model;

Fig. 4 show exemplarily that the utility model adopts an embodiment in the equivalent capacity that connects of topology triangular in shape;

Fig. 5 is for showing the energy conversion efficiency of under different loads (5%, 10%, 20%, 30%, 50%, 100%) based on chart 2;

Fig. 6 exemplarily shows the root locus that embodiment is related of the utility model;

Fig. 7 exemplarily shows the Bode diagram that embodiment is related of the utility model;

Fig. 8 exemplarily shows the analogous diagram of the current waveform of non-filtered device;

Fig. 9 exemplarily shows the analogous diagram of the current waveform behind filter;

Figure 10 exemplarily shows the current spectrum of non-filtered device;

Figure 11 exemplarily shows the current spectrum behind filter;

Figure 12 exemplarily shows the analogous diagram of the current waveform of the equivalent capacity branch road of flowing through;

Figure 13 exemplarily shows the analogous diagram of the current spectrum of the equivalent capacity branch road of flowing through;

Figure 14 exemplarily shows the contrast experiment figure of harmonic current frequency spectrum and IEEE 1547 standards;

Figure 15 exemplarily shows the analogous diagram of comparison of embodiment and IEEE1547/IEEE519, VDE4105 and the BDEW standard room of the utility model.

Embodiment

Understand for technical characterictic, purpose and effect to utility model have more clearly, contrast the embodiment of description of drawings the utility model at present, identical label is represented identical part in each figure.

Fig. 3 exemplarily shows the topological structure sketch map of the convertor assembly system of an embodiment who comprises the utility model.As shown in Figure 3, filter 200 is connected between electrical network 100 and the inverter 300.400 represent the novel energy generating.Filter 200 in the present embodiment contains three groups of filter units.It should be noted that the utility model is not limited to three groups of filter units.With first group of filter unit is example, and first group of filter unit comprises the first reactance Li ₁, the second reactance lg ₁, damping resistance

Equivalent capacity C ₁And grading resistor

The first reactance Li ₁With the second reactance Lg ₁Be and be connected in series.Damping resistance

An end and the second reactance Lg ₁Equivalent parallel.So-called equivalent parallel refers to from inverter 300 sides to be observed, because the impedance of electrical network 100 is very little, under the high frequency state, is equivalent to electrical network 100 and is short-circuit condition, therefore is equivalent to the second reactance Lg ₁With damping resistance

An end parallel connection after again with the first reactance Li ₁Series connection.Work as damping resistance

An end and the second reactance Lg ₁During equivalent parallel, its other end and equivalent capacity C ₁An end connect.

The first reactance Li plays the effect that reduces ripple current and field fluctuation, need choose big reactance value, but be prone to cause flux loss and system saturated, the reduction real-time response.The introducing of the second reactance Lg can cooperate the Li effect, obviously reduces harmonics level, and reduces flux loss, if the charged power transformer of whole generating system, its leakage inductance can replace Lg.

The first reactance L _iThe reactance value and the second reactance L _gReactance value confirm by formula 1-4.Formula 5 can further retrain.

The expression formula of resonance frequency is:

$f_{\mathrm{Res}}=\frac{I_g}{V_i}=\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{L_g+L_i}{L_g{L}_i{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}}$ ---------------(formula 1),

Wherein, I _gBe the output current of electrical network, V _iBe inverter output voltage, L _iBe the reactance of first reactance, L _gBe the reactance of second reactance, C ₁Be equivalent capacity.

To the characteristic of the inverter that is used for generation of electricity by new energy, f _ResUsually the scope of choosing is:

20f ₁≤f _Res≤f _Sw/ 2---------------------(formula 2),

Wherein, f _ResBe resonance frequency, f ₁Be inverter output fundamental frequency, f _SwSwitching frequency for insulated gate bipolar transistor IGBT in the said inverter.Resonance frequency f _ResChoose very crucially, select conference to cause the filter effect of filter poor, select I to cause inverter to burn, thereby cause electrical network to come off, produce " island effect ".

The filter that should be noted in the discussion above that the utility model design can not only be used in the grid-connected power generation system, also can be used in the traditional energy electricity generation system.

In addition, definition L _Total=L _i+ L _g, L _TotalUsually the scope of choosing is:

12%pu≤L _Total≤15%pu-----------------(formula 3),

Wherein, pu is the phase voltage pressure drop.

In addition, L _i/ L _gUsually the scope of choosing is:

2≤L _i/ L _g≤3-----------------(formula 4),

In order to confirm L more accurately _gAnd L _i, also need satisfy following constraints:

${\mathrm{\&Delta;\; i}}_{\mathrm{Max}}=\frac{U_{\mathrm{Dc}}}{{8L}_{\mathrm{Total}}{f}_{\mathrm{Sw}}}\&ap;{\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">K</figure-callout>}}_1*I_N$ ---------------(formula 5),

Wherein, Δ i _MaxBe the maximum of output current fluctuation, U _DcBe DC side photovoltaic battery panel voltage, L _Total=L _i+ L _g, I _NBe said inverter output-current rating, k ₁Be coefficient, it is worth in 15% to 25% scope.

In sum, the first reactance L _iThe reactance value and the second reactance L _gReactance value confirm by above-mentioned.

The first reactance L _iWith the second reactance L _gRated current I _LChoose and can meet:

I _L=k ₂* I _L-------------(formula 6),

Wherein, I _NBe inverter 300 output-current ratings, k ₂Be coefficient, its output characteristic according to inverter 300 confirms that its value can be in 1.1 to 1.2 scope.

Equivalent capacity C ₁With and rated voltage confirm please refer to as follows.

As shown in Figure 3, equivalent capacity C ₁Can be by four capacitor C _ΔBe formed in parallel.It should be noted that shunt capacitance C _ΔNumber be not limited to four, any amount of capacitor C such as two five _ΔAll can and be unified into equivalent capacity C ₁Electric capacity quantity depends on inverter switching frequency and its cut-off frequency.Then, equivalent capacity C ₁Respectively with second group of filter unit in equivalent capacity C ₂And the equivalent capacity C in the 3rd group of filter unit ₃Join end to end, topology triangular in shape connects.(seeing also Fig. 4).Then, every end of triangular form more respectively with every group of filter unit in damping resistance R _DampConnect.

The advantage that equivalent capacity topology triangular in shape connects is; Compare with Y-connection (seeing also Fig. 2); Triangle topology can reduce capacitance to 1/3 times, and electric pressure is corresponding can to improve

doubly.

$\left\{\begin{array}{c}{U}_{\mathrm{\&Delta;}}=\sqrt{3}*U_Y\\ C_{\mathrm{\&Delta;}}=\frac{1}{3}*C_Y\end{array}\right.$ ------------------------(formula 7),

Wherein, U _Δ, U _YBe voltage, C _Δ, C _YBe electric capacity.When reaching the required voltage grade, reduce cost and device volume thus, provide than large space and be beneficial to heat radiation.

Equivalent capacity C ₁Value can meet

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">C</figure-callout>}}_1\&le;\frac{5\%P}{E^2*{2\mathrm{\&pi;\; <figure-callout\; id="1"\; label="f"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">f</figure-callout>}}_1}$ ----------------(formula 8),

Wherein, p is said inverter power output, and E is an inverter output rated line voltage, f ₁Be inverter output fundamental frequency.Formula 8 by

Q _c≤5%P---------------(formula 9),

And

$Q_c=3*{(E/\sqrt{3})}^2*{2\mathrm{\&pi;\; <figure-callout\; id="1"\; label="f"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">f</figure-callout>}}_1<figure-callout\; id="1"\; label="*\; C"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">*</figure-callout>C_{}{}_1$ ---------------(formula 10),

Confirm, wherein, Q _cBe total fundamental wave reactive power power, p is said inverter power output, and E is an inverter output rated line voltage, f ₁Be inverter output fundamental frequency.

The rated voltage U of equivalent capacity _cChoose and can meet:

U _c=k ₃* U _N-----------------(formula 11),

Wherein, U _NBe inverter amount of exports phasing voltage, k ₃Be coefficient, confirm that according to the output characteristic and the electrical network specific requirement of inverter 300 its value can be in 1.5 to 2 scope.

The connection of dihedral topology is prone to through the unbalanced phenomenon of the voltage drop of equivalent capacity, so all can a parallelly connected grading resistor R on each equivalent capacity _Balence, its electric pressure and equivalent capacity are equal to, and power is chosen and is about 2W to prevent too much power loss, reduces filter efficient.

Damping resistance R _DampResistance with and total current confirm please refer to as follows.

Damping resistance

value can meet:

$R_{{\mathrm{Damp}}_1}\&le;\frac{1}{3}*\frac{1}{{2\mathrm{\&pi;\; <figure-callout\; id="1"\; label="f\; Res\; C"\; filenames="HDA0000155712890000061.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{Res}}{C}_{}{}_1}$ --------------(formula 12),

Wherein, f _ResBe resonance frequency, C ₁Be equivalent capacity.Damping resistance needs enough big to prevent the generation of resonance, and simultaneously, the excessive reduction that then can cause efficient is so common R value is smaller or equal to 1/3 of resonance frequency place capacitive reactance.

The total current of damping resistance can meet:

$I_{R_{\mathrm{Damp}}}\&ap;\sqrt{\frac{{(U_N+U_{\mathrm{Lg}})}^2}{{R_{\mathrm{Damp}}}^2+{[1/\left(2{\mathrm{\&pi;\; f}}_{1}C\right)]}^2}+{k_4}^2*{I_N}^2}$ ------------(formula 13),

Wherein, U _NBe inverter amount of exports phasing voltage, U _LgBe the second reactance pressure drop, R _DampBe damping resistance, f ₁Be inverter output fundamental frequency, C ₁Be equivalent capacity, k ₄Be the coefficient relevant, I with inverter _NBe the inverter output-current rating.Formula 13 by

$I_1=\frac{U_N+U_{\mathrm{Lg}}}{\sqrt{{R_{\mathrm{Damp}}}^2+{[1/\left({2\mathrm{\&pi;\; f}}_1{C}_1\right)]}^2}}$ ------------(formula 14),

I _Sw=k ₄* I _N------------(formula 15),

And $I_{R_{\mathrm{Damp}}}\&ap;\sqrt{{I_1}^2+{I_{\mathrm{Sw}}}^2}$ ------------(formula 16),

Confirm, wherein, I ₁For resulting from damping resistance R _DampOn fundamental current, U _NBe inverter amount of exports phasing voltage, U _LgBe the second reactance pressure drop, R _DampBe damping resistance, f ₁Be inverter output fundamental frequency, C ₁Be equivalent capacity, I _SwFor resulting from damping resistance R _DampOn the switching frequency subharmonic current, k ₄Be the coefficient relevant, I with inverter _NBe the inverter output-current rating,

Total current for damping resistance.To certain photovoltaic DC-to-AC converter attribute, k ₄Be about 10%, formula 15 all injects damping resistance R based on whole harmonic currents _DampThe supposition of place branch road.

Following chart 1 has disclosed the concrete data of two embodiment of the utility model.

Chart 1

Following chart 2 illustrates the remarkable technique effect that embodiment of the utility model can obtain.In this embodiment, the first reactance L _i=0.16mH, the second reactance L _g=0.08mH, capacitor C=252uF.

Chart 2

Chart 2 is THD and the energy conversion efficiency of an embodiment under different loads (5%, 10%, 20%, 30%, 50%, 100%).

Fig. 5 is for showing the energy conversion efficiency of under different loads (5%10%20%30%50%100%) based on chart 2.It is thus clear that energy conversion efficiency is all on 99% under 50% load and 100% load.Electric current THD under 100% load less than 1%.

Fig. 6 exemplarily shows the root locus that embodiment is related of the utility model.Transverse axis is a real axis, and the longitudinal axis is the imaginary axis.Fig. 7 exemplarily shows the Bode diagram that embodiment is related of the utility model.Transverse axis is a frequency, and the longitudinal axis 1 is an amplitude, and the longitudinal axis 2 is a phase angle.Can find out that on scheming system is in asymptotic stable state, effectively avoid the generation of resonance phenomena, the harmonic attenuation rate reaches-60dB/dec, thereby effectively reduces current harmonic content, improves the quality of power supply.

Fig. 8 exemplarily shows the analogous diagram of the current waveform of non-filtered device.Its transverse axis is the time, and the longitudinal axis is an electric current.Fig. 9 exemplarily shows the analogous diagram of the current waveform behind filter.Its transverse axis is the time, and the longitudinal axis is an electric current.Figure 10 exemplarily shows the analogous diagram of the current spectrum of non-filtered device.Its transverse axis is a frequency, and the longitudinal axis is an electric current.Figure 11 exemplarily shows the analogous diagram of the current spectrum behind filter.Its transverse axis is a frequency, and the longitudinal axis is an electric current.Can find out the filter effect of the filter that the utility model is related by Fig. 8-11.

Figure 12 exemplarily shows the analogous diagram of the current waveform of the equivalent capacity branch road of flowing through, and its transverse axis is the time, and the longitudinal axis is an electric current; Figure 13 exemplarily shows the analogous diagram of the current spectrum of the equivalent capacity branch road of flowing through, and its transverse axis is a frequency, and the longitudinal axis is an electric current.Last two figure show that the current harmonics of inverter output is absorbed by capacitive branch, thereby guarantees that its output waveform presents the sinusoidal waveform of perfect harmony under the effect of filter.

Figure 14 exemplarily shows the lab diagram of the comparison of harmonic current frequency spectrum and IEEE1547 standard.Its transverse axis is a harmonic number, and the longitudinal axis is an electric current.Under the EEE1547 standard, THD is smaller or equal to 5%.The THD of the utility model is about 1%.

Figure 15 exemplarily shows the analogous diagram of comparison of embodiment and IEEE1547/IEEE519, VDE4105 and the BDEW standard room of the utility model.Show that by figure the utility model is high to the harmonic attenuation rate, meets harmonic wave control standards such as IEEE1547/IEEE519, VDE4105 and BDEW, thereby has reduced ' pollution ' to the electrical network quality of power supply.

Above-mentioned listed detailed description only is specifying to the feasibility embodiment of the utility model; It is not protection range in order to restriction the utility model; Protection range is as the criterion with claim, and all equivalence or changes that does not break away from the spiritual embodiment that is done of the utility model all should be included within the protection range of the utility model.

Claims (8)

1. harmonic filter that is used to filter inverter comprises:

At least one group of filter unit, every group of said filter unit comprises:

The first reactance L _i

The second reactance L that connects with said first reactance _g

One end and the said second reactance L _gThe damping resistance of equivalent parallel; And

The equivalent capacity that one end is connected with the other end of said damping resistance; Wherein, the said first reactance L _iReactance value and the said second reactance L _gReactance value in following scope:

$20f_1\&le;\frac{1}{2\mathrm{\&pi;}}\sqrt{\frac{L_g+L_i}{L_g{L}_{i}C}}\&le;f_{\mathrm{sw}}/2,$

12%pu≤L _i+ L _g≤15%pu and

2≤L _i/L _g≤3，

Wherein, C is an equivalent capacity, f ₁Be the fundamental frequency of said inverter output, f _SwBe igbt switching frequency in the said inverter, pu is the phase voltage pressure drop.

2. according to claim 1 or claim 2 filter is characterized in that the said first reactance L _iReactance value and the said second reactance L _gReactance value also by constraints

Revise, wherein, U _DcBe the DC bus-bar voltage of said inverter, I _NBe said inverter output-current rating, k ₁Be coefficient, it is worth in 15% to 25% scope.

3. according to claim 1 or claim 2 filter is characterized in that said filter is used for wind power generation or photovoltaic generation.

4. according to claim 1 or claim 2 filter; It is characterized in that; Said filter comprises three groups of filter units, contains first filter unit of first equivalent capacity and first damping resistance, contains second filter unit of second equivalent capacity and second damping resistance; And the 3rd filter unit that contains C grade effect electric capacity and the 3rd damping resistance; Said first, second, third equivalent capacity joins end to end separately, and topology triangular in shape connects, and three tie points of said electric capacity are connected with an end of said first, second, third damping resistance respectively.

5. according to claim 1 or claim 2 filter is characterized in that the total current of said damping resistance $I_{R_{\mathrm{Damp}}}\&ap;\sqrt{\frac{{(U_N+U_{\mathrm{Lg}})}^2}{{R_{\mathrm{Damp}}}^2+{[1/\left(2{\mathrm{\&pi;\; f}}_{1}C\right)]}^2}+{k_4}^2*{I_N}^2},$ Wherein, U _NBe said inverter amount of exports phasing voltage, U _LgBe the said second reactance pressure drop, R _DampBe said damping resistance resistance, f ₁Be the fundamental frequency of said inverter output, C is said equivalent capacity, k ₄Be the coefficient relevant, I with said inverter _NBe said inverter output-current rating.

6. according to claim 1 or claim 2 filter is characterized in that said equivalent capacity C value meets P is said inverter power output, and E is said inverter output rated line voltage, f ₁Fundamental frequency for said inverter output.

7. according to claim 1 or claim 2 filter is characterized in that said equivalent capacity is parallelly connected with a grading resistor.

8. according to claim 1 or claim 2 filter is characterized in that, said second reactance is the leakage inductance of power transformer of the system at said filter place.

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