CN103515960A - Magnetic integrated type hybrid power filter and reactive compensation system - Google Patents

Abstract

The invention discloses a magnetic integrated type hybrid power filter and reactive compensation system which comprises a five-winding transformer. A primary-side high-voltage winding of the five-winding transformer is connected with an alternating-current power network, a secondary-side low-voltage winding is connected with a current transformer, the current transformer is connected with a load, and two inductive filter windings of the five-winding transformer are connected with one filter capacitor bank. An active filter winding is connected with an active filter, a first current measurement device is arranged between the inductive filter windings and the filter capacitor bank, a second current measurement device is arranged between the secondary-side low-voltage winding and the transformer, the first current measurement device and the second current measurement device are respectively connected with an instruction current arithmetic unit, the instruction current arithmetic unit is connected with a PWM controller, and the PWM controller is connected with the active filter. The inductive filter and the active filter are combined, the magnetic integrated type hybrid power filter and reactive compensation system has the advantages of being high in integration degree, small in size, full in tuning and free of harmonic enlargement and achieves harmonic and reactive nearest dynamic continuous governance.

Description

The hybrid power filtering of magnetic integrated form and reactive compensation system

Technical field

The present invention relates to harmonic wave control and the reactive power compensation field of power distribution network, particularly a kind of magnetic integrated form hybrid power filtering and reactive compensation system.

Background technology

At present a large amount of uses of power electronic device in power distribution network, have inevitably produced that system harmonics is seriously polluted, power factor low, the power quality problem such as voltage flicker and imbalance.Along with the development of intelligent grid, power consumption equipment is more responsive to the quality of power supply, and the power supply quality of electrical network is had higher requirement, and the harmonic wave control of electrical network and reactive power compensation have become the important content of research.

At present, there are passive filtering, active power filtering and mixing active power filtering improving main filtering technique aspect the quality of power supply.Wherein, passive filtering because apparatus structure is fairly simple, design and manufacturing than being easier to, and initial investment cost is lower, in electric power system and industrial adapted electric system, has obtained being widely used.Yet the Filtering Efficacy of passive filter is easily subject to the restriction of system impedance.When electric power networks structure changes, likely cause the series/parallel resonance between filtering impedance and system impedance, this not only affects electric power system stability, and has limited the performance of filtering performance.

Along with the develop rapidly of power electronic technology, the continuous progress of high-power turn-off device (GTR, GTO, IGBT etc.), and the further investigation of harmonic wave Test and control, active power filtering is widely used in electric power system.Compare with passive filter, active power filtering has controllability and the fast-response of height, the harmonic wave can automatic tracking and compensating changing, and filtering characteristic is not subject to the impact of system impedance, can eliminate the danger with system impedance generation resonance.Although active power filtering has the not available huge technical advantage of passive filter, owing to being subject to the restriction of switching device, its cost is higher, and the increase of capacity is limited.Current high-power filter, from considering economically, generally adopts the mixed active filtering system of active power filtering use in parallel with passive filter to reduce the capacity of active power filtering, reaches and reduces costs, the object of raising the efficiency.But mixed filtering is due to the possibility of having used the same existence of passive filter with electric network impedance generation resonance.

It is worthy of note especially, no matter above-mentioned filtering mode is passive filtering, active power filtering or mixed filtering, be mainly with solving harmonic wave and the harmful effect of idle component to electrical network, but for the electric power system connecting for electrical network self, do not obtain useful improvement.The free flow and do not obtain any inhibition in electric power system of the harmonic wave being produced by nonlinear-load and idle component, this has not only worsened the electromagnetic environment of main equipment in electric power system, supplementary load loss, the noise and vibration of main equipment have been increased, and the stability of a system and operational efficiency have been reduced, in addition, isolating transformer in passive filter in filter reactor and active filter is all self-existent, makes the volume of filter large, effectively high material consumption.

Summary of the invention

In order to solve the problems of the technologies described above, the invention provides that a kind of volume is little, cost is low and can eliminate magnetic integrated form hybrid power filtering and the reactive compensation system of network system impedance to Filtering Efficacy restrictive function.

The technical scheme that the present invention addresses the above problem is: a kind of magnetic integrated form hybrid power filtering and reactive compensation system, comprise five-winding transformer, current transformer, filtering capacitor group, active filter, instruction current arithmetic unit and PWM controller, described five-winding transformer comprises primary side high pressure winding, secondary side low pressure winding, two induction Filter Winding and an active power filtering winding, wherein primary side high pressure winding is connected with AC network, secondary side low pressure winding is connected with current transformer, current transformer is connected with load, two induction Filter Winding of five-winding transformer are all connected with a filtering capacitor group, active power filtering winding is connected with active filter, between described induction Filter Winding and filtering capacitor group, be provided with the first current measuring device, between described secondary side low pressure winding and current transformer, be provided with the second current measuring device, described the first current measuring device, the second current measuring device respectively and instruction current operator device is connected, instruction current arithmetic unit is connected with PWM controller, PWM controller is connected with active filter.

Described magnetic integrated form hybrid power filtering and reactive compensation system also comprise high pass filter, and described high pass filter is connected with active filter, active power filtering winding respectively.

One described of two filtering capacitor group are 5 times or 11 characteristic harmonics filtering capacitor groups, and another is 7 times or 13 characteristic harmonics filtering capacitor groups.

Described the first current measuring device is current sensor.

Described the second current measuring device is current sensor.

Beneficial effect of the present invention is:

(1) the present invention adopts integrated magnetic, be designed to five-winding transformer, make the equivalent leakage reactance of two induction Filter Winding of this five-winding transformer under specific subfrequency, can reach series resonance state be connected filtering capacitor group completely respectively, then by the electromagnetic induction mechanism of five-winding transformer inside, characteristic harmonics is carried out to filtering, and first-harmonic is carried out to reactive power compensation.This kind induction filtering needn't consider network system impedance impact to carry out the humorous design of loaded down with trivial details offset, fundamentally broken away from the restrictive function of network system impedance to Filtering Efficacy, in addition, filter reactor is complete and five-winding transformer is integrated, has eliminated by the shared volume of filter reactor.

(2) five-winding transformer active power filtering winding of the present invention is connected with active filter, other subharmonic except induction filtering filtering harmonic wave are carried out to filtering, and first-harmonic is carried out to reactive power compensation, this is equivalent to, by the integrated distribution transformer of isolating transformer magnetic of active filter, eliminate the shared volume of isolating transformer.

(3) the present invention can be in close nonlinear load side, realize harmonic wave and idle inhibition nearby and compensation, this has not only reduced supplementary load loss, temperature rise, the noise and vibration of described five-winding transformer, and has realized High Power Factor and the high-efficiency stable operation of whole industrial rectifier power system.

Accompanying drawing explanation

Fig. 1 is electrical block diagram of the present invention.

Fig. 2 is single-phase equivalent circuit diagram of the present invention.

In Fig. 1: 1, five-winding transformer, 2, the first filtering capacitor group, the 3, second filtering capacitor group, 4, instruction current arithmetic unit, 5, PWM controller, 6, the first current measuring device, the 7, second current measuring device, 8, high pass filter, 9, current transformer, 10, load, 11, AC network, 12, active filter;

In Fig. 2: L ₁, L ₂, L ₃, L ₄, L ₅the primary side high pressure winding, secondary side low pressure winding, the first induction Filter Winding, second that are respectively five-winding transformer are responded to the equivalent inductance of Filter Winding, active power filtering winding; L _sequivalent inductance for electrical network; C ₃, C ₄be respectively the filter capacitor of the first filtering capacitor group, the second filtering capacitor group; I _l1, I _lhfor load-side fundamental reactive current and harmonic current; I ₃₁, I _3hbe the first induction Filter Winding lateral capacitance load fundamental reactive current and harmonic current; I ₄₁, I _4hbe the second induction Filter Winding lateral capacitance load fundamental reactive current and harmonic current; I ₅₁, I _5hfundamental reactive current and harmonic current for active filter generation; I _s1, I _shgrid side fundamental reactive current and harmonic current.

Embodiment

Below in conjunction with drawings and Examples, the present invention is further illustrated.

As shown in Figure 1, the present invention includes five-winding transformer 1, the first filtering capacitor group 2, the second filtering capacitor group 3, instruction current arithmetic unit 4, PWM controller 5, the first current measuring device 6, the second current measuring device 7, high pass filter 8, current transformer 9, active filter 12, described five-winding transformer 1 comprises primary side high pressure winding, secondary side low pressure winding, the first induction Filter Winding, the second induction Filter Winding and active power filtering winding, wherein primary side high pressure winding is connected with AC network 1, and secondary side low pressure winding is connected with current transformer 9, and current transformer 9 is connected with load 10, the first induction Filter Winding of five-winding transformer, second induction Filter Winding respectively with the first filtering capacitor group 2, the second filtering capacitor group 3 is connected, and active power filtering winding is connected with active filter 12, between described the first induction Filter Winding and the first filtering capacitor group 2, between the second induction Filter Winding and the second filtering capacitor group 3, be provided with the first current measuring device 6, between described secondary side low pressure winding and current transformer 9, be provided with the second current measuring device 7, described the first current measuring device 6, the second current measuring device 7 is current sensor, described the first current measuring device 6, the second current measuring device 7 respectively and instruction current operator devices 4 is connected, and instruction current arithmetic unit 4 is connected with PWM controller 5, and PWM controller is connected with active filter 12, described high pass filter 8 respectively with active filter 12, active power filtering winding is connected, described the first filtering capacitor group 2 is 5 times or 11 characteristic harmonics filtering capacitor groups, and the second filtering capacitor group 3 is 7 times or 13 characteristic harmonics filtering capacitor groups.

The first filtering capacitor group 2, the second filtering capacitor group 3 are mated respectively complete resonance are occurred 5,7 (or 11,13 times) characteristic harmonics to the equivalent leakage inductance of the first induction Filter Winding, the second induction Filter Winding, and 5,7 (or 11,13 times) characteristic harmonics that current transformer 9 is produced are responded to filtering.Instruction current arithmetic unit 4 inputs and the first current measuring device 6, the second current measuring device 7 is connected, the electric current that the first current measuring device 6, the second current measuring device 7 are measured carries out analytic operation, the instruction current of output active filter 12, removes the humorous reactive current that involves that induction still needs compensation after filtering.Instruction current arithmetic unit 4 outputs are connected with PWM controller 5, and PWM controller 5 is accepted instruction current information, control active filter 12 and produce the humorous reactive current that involves needing.Bivalent high-pass filter 8 is used for the high-frequency harmonic that filtering active filter 12 produces.

The mixed filtering mode that the present invention adopts induction filtering and active power filtering to combine, has reached the effect of traditional passive filtering and active power filtering, and have highly integrated, volume is little; Complete modulation, the feature of amplifying without harmonic wave, realized harmonic wave and idle dynamically administering continuously nearby, makes grid side obtain high-quality electric energy.

Fig. 2 has set forth filtering of the present invention and Principles of Reactive Compensation.If h (h=5,7,11,13) characteristic harmonic current I that consideration current transformer 9(harmonic source) side produces _lh, harmonic current I _lhbe fed into the content I of the grid side h subharmonic current that grid side causes _sh, be also the h subharmonic current I of the primary side high pressure winding existence of five-winding transformer 1 _1h, can be expressed as:

$I_{1h}=\frac{I_{\mathrm{Lh}}[(\mathrm{jh\ω}{L}_3-j/\mathrm{h\ω}{C}_3)//(\mathrm{jh\ω}{L}_4-j/\mathrm{h\ω}{C}_4)//(\mathrm{jh\ω}{L}_1+\mathrm{jh\ω}{L}_3)]}{\mathrm{jh\ω}{L}_1+\mathrm{jh\ω}{L}_s}---\left(1\right)$

Harmonic current I _lhbe fed into first of five-winding transformer 1 and respond to the h subharmonic current content I that Filter Winding causes _3hcan be expressed as:

$I_{3h}=\frac{I_{\mathrm{Lh}}[(\mathrm{jh\ω}{L}_3-J/\mathrm{h\ω}{C}_3)//(\mathrm{jh\ω}{L}_4-j/\mathrm{h\ω}{C}_4)//(\mathrm{jh\ω}{L}_1+\mathrm{jh\ω}{L}_s)]}{\mathrm{jh\ω}{L}_3-j/\mathrm{h\ω}{C}_3}---\left(2\right)$

Harmonic current I _lhbe fed into second of five-winding transformer 1 and respond to the h subharmonic current content I that Filter Winding causes _4hcan be expressed as:

$I_{4h}=\frac{I_{\mathrm{Lh}}[(\mathrm{jh\ω}{L}_3-j/\mathrm{h\ω}{C}_3)//(\mathrm{jh\ω}{L}_4-j/\mathrm{h\ω}{C}_4)//(\mathrm{jh\ω}{L}_1+\mathrm{jh\ω}{L}_3)]}{\mathrm{jh\ω}{L}_4-j/\mathrm{h\ω}{C}_4}---\left(3\right)$

The equivalent leakage reactance L of design the first induction Filter Winding ₃be connected filter capacitor C ₃under 5 subfrequencies, can reach series resonance state, i.e. 25 ω completely ²l ₃c ₃=1.

Now, I _s5=0, I ₄₅=0, I ₃₅=I _l5, visible rectifier 9(harmonic source) and 5 characteristic harmonic current I producing of side _l5burst completely into the first induction Filter Winding, five-winding transformer primary side, the second induction Filter Winding side are without 5 subharmonic currents.

The equivalent leakage reactance L of design the second induction Filter Winding ₄be connected filter capacitor C ₄under 7 subfrequencies, can reach series resonance state, i.e. 49 ω completely ²l ₄c ₄=1.

Now, I _s7=0, I ₃₇=0, I ₄₇=I _l7, visible rectifier 9(harmonic source) and 7 characteristic harmonic current I producing of side _l7burst completely into the second induction Filter Winding, transformer primary side, the first induction Filter Winding are without 7 subharmonic currents.

By instruction current arithmetic unit 4 and PWM controller 5, make active filter 12 produce compensation harmonic electric currents (removing 5,7 characteristic harmonics or 11,13 characteristic harmonics) and meet following relation (N wherein ₁, N ₂, N ₃, N ₄, N ₅represent the number of turn of each winding):

N ₅I _5h=N ₂I _Lh-N ₃I _3h-N ₄I _4h （3）

Again because five-winding transformer 1 ampere-turn equilibrium principle can be known:

N ₅I _5h=N ₂I _Lh-N ₃I _3h-N ₄I _4h-N ₁I _sh （4）

By (3) (4), can obtain I _sh=0.

From upper analysis, it is zero substantially that the mixed filtering mode by induction filtering and active power filtering makes grid side harmonic current.

For fundamental wave reactive power compensation principle, induction filtered side filter capacitor has carried out part reactive power compensation.Remain idle instruction current arithmetic unit 4 and the PWM controller 5 of passing through, by active filter 12, produced, its fundamental reactive current meets following relation:

N ₅I ₅₁=N ₂I _L1-N ₃I ₃₁-N ₄I ₄₁ （5）

Again because five-winding transformer ampere-turn equilibrium principle can be known:

N ₅I ₅₁=N ₂I _L1-N ₃I _3h-N ₄I ₄₁-N ₁I _s1 （6）

By (5) (6), can obtain I _s1=0.

To sum up analyze, the enforcement of induction filtering and active power filtering hybrid system, has realized harmonic wave and idle dynamically administering continuously nearby, makes grid side obtain high-quality electric energy.

The above embodiment has only expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as limitation of the scope of the invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with claims.

Claims (5)

1. a magnetic integrated form hybrid power filtering and reactive compensation system, it is characterized in that: comprise five-winding transformer, current transformer, filtering capacitor group, active filter, instruction current arithmetic unit and PWM controller, described five-winding transformer comprises primary side high pressure winding, secondary side low pressure winding, two induction Filter Winding and an active power filtering winding, wherein primary side high pressure winding is connected with AC network, secondary side low pressure winding is connected with current transformer, current transformer is connected with load, two induction Filter Winding of five-winding transformer are all connected with a filtering capacitor group, active power filtering winding is connected with active filter, between described induction Filter Winding and filtering capacitor group, be provided with the first current measuring device, between described secondary side low pressure winding and current transformer, be provided with the second current measuring device, described the first current measuring device, the second current measuring device respectively and instruction current operator device is connected, instruction current arithmetic unit is connected with PWM controller, PWM controller is connected with active filter.

2. magnetic integrated form hybrid power filtering as claimed in claim 1 and reactive compensation system, is characterized in that: also comprise high pass filter, described high pass filter is connected with active filter, active power filtering winding respectively.

3. magnetic integrated form hybrid power filtering as claimed in claim 1 and reactive compensation system, it is characterized in that: one described of two filtering capacitor group are 5 times or 11 characteristic harmonics filtering capacitor groups, another is 7 times or 13 characteristic harmonics filtering capacitor groups.

4. magnetic integrated form hybrid power filtering as claimed in claim 1 and reactive compensation system, is characterized in that: described the first current measuring device is current sensor.

5. magnetic integrated form hybrid power filtering as claimed in claim 1 and reactive compensation system, is characterized in that: described the second current measuring device is current sensor.

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