CN101577424A - Direct current electric power filtration method - Google Patents
Direct current electric power filtration method Download PDFInfo
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- CN101577424A CN101577424A CNA2009101169247A CN200910116924A CN101577424A CN 101577424 A CN101577424 A CN 101577424A CN A2009101169247 A CNA2009101169247 A CN A2009101169247A CN 200910116924 A CN200910116924 A CN 200910116924A CN 101577424 A CN101577424 A CN 101577424A
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Abstract
A direct current electric power filtration method is characterized in that: a primary side of a converter with a transformation ratio of n is sealed in an incoming line of a filtered unit, an inductance L is bridge connected with a secondary side of the converter, the impedance of non-DC Value of the inductance L to frequency f is according to the equation Zf=2pifL; on the primary side of the converter, the DC resistance is zero and an equivalent impedance of non-DC Value to frequency f is Zf/n<2>; the harmonic wave is inhibited to be sealed in a three phase current system in DC-ON and AC-OFF mode to realize full range electric power filtration. The electric power filtration method of the invention is better than active power filtering and has the advantages of reliable method, simple equipment, easy manufacture, convenient operation and maintain and low cost.
Description
Technical field
The present invention relates to the method for direct current electric power filtration.
Background technology
The harmonic load electric current is produced by nonlinear-load.Harmonic wave is to be produced by the equipment that interchange is converted to direct current in a lot of electrical networks, as rectifying installation, milling train, arc furnace etc.On the one hand, along with expanding economy, produce the device type and the quantity sharp increase of harmonic wave; On the other hand, along with being the popularization and application of the sensitive equipment of representative with the computer, more and more higher for the power supply quality requirement of utility network, harmonic standard has separately been formulated in many countries and regions, in order to the harmonic pollution of restriction electric power system and power consumption equipment.
The harmfulness of AC harmonic is very big, mainly contains: the thyristor units to contiguous weak electricity system and parallel running produces interference; The allowable load of generator is reduced; Make that noise of transformer increases, power loss increases; Make the capacitor overload of incoming transport system; Cause the additional heating of electrical equipment; Harmonic wave can make neutral line overload in the three-phase and four-line circuit; Make the change of induction motor rotating speed generating period, and its power loss (iron loss, copper loss) is increased; Make the degraded accuracy of instrument transformer; Influence the work of electronic computer; The harm cable life quickens cable and wears out.
Improvement for harmonic wave at present comprises:
1, dynamic reactive compensation device is set, to improve the ability that electric power system is born harmonic wave
Under the feasible condition of technical economic analysis, can dynamic reactive compensation device be set at the harmonic source place, comprise static passive compensation device (SVC-Static Var Compensator) or more advanced static synchronous compensator plant (STATCOM StaticSynchronous Compensator), to obtain the quick reactive requirement that changes of compensation load, improve power factor, filtering appts harmonic wave, to reduce to system and inject harmonic current, stablize busbar voltage, reduce imbalance of three-phase voltage degree etc., the ability that the raising electric power system is born harmonic wave.
2, passive filtration unit is set, so that the filtering harmonic wave
Adopt passive component, comprise the tuning filtering device that capacitor, reactor and resistor are formed, the filtering harmonic wave alleviates the harm of harmonic wave to electric equipment.
3, adopt the active filter harmonic carcellation
Utilization can be turn-offed the harmonic component equal and opposite in direction in power electronic device generation and the load current, and the electric current that phase place is opposite comes harmonic carcellation.
Above-mentioned each class methods all have certain effect for harmonic carcellation, but device therefor involves great expense, and are millions of easily even several ten million, and the general user is difficult to bear.
Summary of the invention
The present invention is for avoiding above-mentioned existing in prior technology problem, a kind of power filtering method is provided, and performance is better than the effect of active power filtering, and its method is reliable, equipment simple, be easy to make, operation maintenance is simple and convenient, cost is low.
The technical scheme that technical solution problem of the present invention is adopted is:
The characteristics of direct current electric power filtration method of the present invention are to be that the primary side of the current transformer of n seals in the inlet wire of filtered unit with the no-load voltage ratio, and in the secondary side cross-over connection inductance L of described current transformer, described inductance L is Z to the impedance of the non-DC quantity of frequency f
f=2 π fL; At the primary side of described current transformer, be 0 for the direct current resistance, be Z for the equiva lent impedance of the non-DC quantity of frequency f
f/ n
2, the form inhibition harmonic wave that exchanges with its perfectly straight stream, resistance seals in the three-phase alternating current system, realizes the full frequency band electric filtering.
The characteristics of direct current electric power filtration method of the present invention are that also parallel connection is used to consume the resistive element of interchange on inductance L.
Figure 2 shows that filtering operation principle of the present invention, wherein, ZLQ is a rectifying device, and BLQ is a current transformer, and L is an inductance, and FH is load.
The direct current of ZLQ rectifying device output, during through current transformer BLQ, because the magnetic field that on the iron core of current transformer BLQ, does not change, so secondary side no current output at current transformer BLQ, so there is not inhibition in inductance L to direct current, that is to say that for direct current the primary side resistance of current transformer L is 0;
Non-direct current for the output of ZLQ rectifying device, since the magnetic field that on the iron core of current transformer BLQ, changes, at the secondary side of current transformer BLQ electric current output is arranged, so there is inhibition in inductance L to non-direct current, that is to say that for non-direct current the primary side resistance of current transformer L is not 0.
Inductance L is to the non-DC quantity of frequency f, and its resistance value is Z
f=2 π fL; At the primary side of current transformer, be 0 for the direct current resistance, be Z to the non-DC quantity equivalent impedance of frequency f
f/ n
2, perfectly straight flow resistance exchanges, and seals in the three-phase alternating current system thereby suppress harmonic wave, realizes the full frequency band electric filtering.
Description of drawings
Fig. 1 is the filtering principle figure of the inventive method.
Fig. 2 is the filtering fundamental diagram of the inventive method.
Fig. 3 is another embodiment circuit theory diagrams of the present invention.
Fig. 4 is current transformer primary side resistance-frequency relation figure in the inventive method
Below, the inventive method and equipment are described further by embodiment:
Embodiment
Embodiment 1:
As shown in Figure 1 and Figure 2, ZLQ is the three phase rectifier device, and FH is load, and BLQ is a current transformer, and its no-load voltage ratio is 1: 1, and the secondary side of current transformer is connected to inductance L, and the resistance of 50Hz frequency is Z
50=20 Ω are Z to the resistance of 100Hz frequency
100=40 Ω are Z to the resistance of 150Hz frequency
150=60 Ω are Z to the resistance of 350Hz frequency
300=140 Ω are Z to the resistance of 550Hz frequency
550=220 Ω, the resistance of BLQ primary side is respectively: resistance 20 Ω of 50Hz frequency, resistance 40 Ω of 100Hz frequency, resistance 60 Ω of 150Hz frequency, resistance 140 Ω of 350Hz frequency are 220 Ω to the resistance of 550Hz frequency.And be 0 for the direct current resistance.
Usually the resistance in rectifying device and the load loop only has the resistance at several ohm of zero points, owing to increase very big resistance therein, the amplitude of non-DC quantity electric current greatly reduces, thereby reach the purpose of filtering, the non-DC quantity that frequency is high more, resistance is high more, and filter effect is good more.
Embodiment 2:
Shown in Figure 2, ZLQ is the three phase rectifier device, and FH is load, and BLQ is a current transformer, and its no-load voltage ratio is 1: 1, and the secondary side of current transformer is connected to inductance L, and the resistance of 50Hz frequency is Z
50=40 Ω are Z to the resistance of 100Hz frequency
100=80 Ω are Z to the resistance of 150Hz frequency
150=120 Ω are Z to the resistance of 350Hz frequency
300=280 Ω are Z to the resistance of 550Hz frequency
550=440 Ω, the resistance of BLQ primary side is respectively: resistance 40 Ω of 50Hz frequency, resistance 80 Ω of 100Hz frequency, resistance 120 Ω of 150Hz frequency, resistance 280 Ω of 350Hz frequency are 440 Ω to the resistance of 550Hz frequency.And be 0 for the direct current resistance.
Usually the resistance in rectifying device and the load loop only has the resistance at several ohm of zero points, owing to increase very big resistance therein, the amplitude of non-DC quantity electric current greatly reduces, thereby reach the purpose of filtering, the non-DC quantity that frequency is high more, resistance is high more, and filter effect is good more.
Embodiment 3:
As shown in Figure 3, ZLQ is the three phase rectifier device, and FH is load, and BLQ is a current transformer, and its no-load voltage ratio is 1: 1, and R is that resistance is in parallel with inductance L, and resistance is 150 Ω, and the secondary side of current transformer is connected to inductance L, and the resistance of 50Hz frequency is Z
50=40 Ω are Z to the resistance of 100Hz frequency
100=80 Ω are Z to the resistance of 150Hz frequency
150=120 Ω are Z to the resistance of 350Hz frequency
300=280 Ω are Z to the resistance of 550Hz frequency
550=440 Ω.The resistance of BLQ primary side is respectively: resistance 40 Ω of 50Hz frequency, and resistance 80 Ω of 100Hz frequency, resistance 120 Ω of 150Hz frequency, resistance 150 Ω of 350Hz frequency are 150 Ω to the resistance of 550Hz frequency.And be 0 for the direct current resistance.
Since the parallel connection of inductance L two ends resistance R, work as Z
FDuring＞R value, no longer change in the resistance of the primary side of current transformer BLQ, R act as the energy that consumes non-DC quantity.
Figure 4 shows that current transformer primary side resistance-frequency relation figure, current transformer primary side resistance is directly proportional with the frequency of non-DC quantity, and frequency is high more, and current transformer primary side resistance is big more, and filter effect is good more.
Claims (2)
1, the method for direct current electric power filtration is characterized in that with the no-load voltage ratio being that the primary side of the current transformer of n seals in the inlet wire of filtered unit, and in the secondary side cross-over connection inductance L of described current transformer, described inductance L is Z to the impedance of the non-DC quantity of frequency f
f=2 π fL; At the primary side of described current transformer, be 0 for the direct current resistance, be Z for the equiva lent impedance of the non-DC quantity of frequency f
f/ n
2, the form inhibition harmonic wave that exchanges with its perfectly straight stream, resistance seals in the three-phase alternating current system, realizes the full frequency band electric filtering.
2, the method for direct current electric power filtration according to claim 1 is characterized in that parallel connection is used to consume the resistive element of interchange on described inductance L.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009101169247A CN101577424A (en) | 2009-06-01 | 2009-06-01 | Direct current electric power filtration method |
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| Application Number | Priority Date | Filing Date | Title |
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| CNA2009101169247A CN101577424A (en) | 2009-06-01 | 2009-06-01 | Direct current electric power filtration method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102938303A (en) * | 2012-11-19 | 2013-02-20 | 北京天诚同创电气有限公司 | Three-phase reactor applied to three-phase four-wire system grid-connected converter |
| CN105262331A (en) * | 2015-11-27 | 2016-01-20 | 云南电网有限责任公司电力科学研究院 | High current DC filter |
-
2009
- 2009-06-01 CN CNA2009101169247A patent/CN101577424A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102938303A (en) * | 2012-11-19 | 2013-02-20 | 北京天诚同创电气有限公司 | Three-phase reactor applied to three-phase four-wire system grid-connected converter |
| CN102938303B (en) * | 2012-11-19 | 2015-08-19 | 北京天诚同创电气有限公司 | Three-phase reactor applied to three-phase four-wire system grid-connected converter |
| CN105262331A (en) * | 2015-11-27 | 2016-01-20 | 云南电网有限责任公司电力科学研究院 | High current DC filter |
| CN105262331B (en) * | 2015-11-27 | 2017-10-13 | 云南电网有限责任公司电力科学研究院 | A kind of heavy DC wave filter |
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Open date: 20091111 |