WO2009062432A1

WO2009062432A1 - Zero-phase-sequence impedance adjusting device and method of zero-phase-sequence current filter

Info

Publication number: WO2009062432A1
Application number: PCT/CN2008/072604
Authority: WO
Inventors: Wei-Ting Lu
Original assignee: Lu, Hsaio-Ting
Priority date: 2007-10-26
Filing date: 2008-10-07
Publication date: 2009-05-22
Also published as: CN101420125B; CN101420125A

Abstract

A zero-phase-sequence impedance adjusting device and method of a zero-phase-sequence current filter adjusts the zero-phase-sequence impedance of a zero phase filter having a common terminal between a multi-phase AC power and a load. The device and method includes an obturator having two terminals and one or more taps, an input neutral wire and an output neutral wire, the input neutral wire connects with the AC power, the output neutral wire connects with the load, the common terminal of the zero-phase-sequence filter connects with the input neutral wire and the output neutral wire through the obturator, the zero-phase-sequence of the zero-phase-sequence filter in parallel with the load is changed by changing the tap of the obturator.

Description

Apparatus and method for zero phase sequence impedance adjustment of zero phase sequence current filter

(1) Technical field

The present invention relates to a zero phase sequence current filter for a multiphase AC power supply; in particular, the present invention relates to zero phase sequence impedance adjustment of a zero phase sequence current filter.

(2) Background technology

In a 3-phase 4-wire power distribution system, if the load is unbalanced, a zero-phase component current will appear in the neutral line of the power distribution system. All zero-phase sequence currents are in phase with each other and there is no phase sequence between them, so the amount of zero-phase sequence current in the neutral line is three times the amount of phase-zero zero-phase current. However, regardless of whether the load is balanced or not, the non-linear load on the 3-phase 4-wire distribution system will cause the zero-phase current to appear on the neutral line. Therefore, due to the large amount of non-linear loads used in general commercial buildings using three-phase four-wire power distribution systems, the amount of neutral phase zero-phase component current in a typical commercial building may sometimes exceed the phase current.

Among them, the zero-phase current of the neutral line has long been considered to be detrimental to system operation, and may cause problems such as neutral overload, transformer overheating, available system capacity reduction, increased power loss and other known problems.

Many systems are recommended to handle neutral zero-phase currents in 3-phase 4-wire power distribution systems, but they are more complex and expensive, and require complex electronics that make them more cumbersome to use.

In 3-phase 4-wire power distribution systems, zero-phase-sequence harmonics are typically controlled using a zero-phase-sequence filter with a low-zero phase-sequence impedance zero-phase sequence. Zero phase-sequence harmonics flowing into the distribution system are effectively reduced by low zero-phase sequence impedance to attract zero-phase harmonic currents. Among them, the most commonly used zero-phase sequence filter is a zigzag-connected reactor or autotransformer, which is often used in three-phase four-wire power distribution system for control due to its price, reliability and ease of installation. The zero phase sequence current of the line. It is commonly used in three-phase four-wire power distribution systems to control the zero-phase current of the neutral line.

Although, a zero-phase-sequence filter is often designed to provide the lowest possible impedance for a zero-phase sequence current, and an occluder is interposed between the zero-phase-sequence filter and the power supply to force zero-phase current as much as possible. Most of the neutral lines flow into the zero-phase sequence filter and prevent a large amount of zero-phase sequence current from flowing into the power distribution system. however, In some special system requirements, it requires a high impedance; for example, in power distribution systems, especially in commercial buildings, new system requirements may increase due to the relatively frequent expansion of equipment. Under such conditions, in the power distribution system, the existing zigzag filter must be removed to accommodate this special high impedance; and for the needs of this high-impedance condition, a customized design The zigzag filter will be replaced.

1 is a prior art icon to show a zero phase sequence current filter with an adjustable zero phase sequence impedance comprising first, second and third core legs, each core foot having first and second The coils are connected into a zigzag type reactor, and each of the first coils 3a1, 3b1, 3cl has an input terminal 13al, 13b1, 13cl for connecting to one of the phases a, b, c of the three-phase power supply network, each second An end point of the coils 3a2, 3b2, 3c2 is connected to a common end point N for connection to a neutral conductor, and the number of active turns of the first coil and the effective number of turns of the second coil are changed using the same core foot The relative ratio is used as a means of adjusting the zero phase sequence impedance. It is provided with one or more taps on one of the coils on each leg by a zigzag filter of a zero phase sequence, or one or more taps on one of the auxiliary coils 3a3, 3b3, 3c3 The joints 13a2, 13b2, 13c2, 13a3, 13b3, 13c3 are connected to one of the coils on each of the core legs; if desired, by means of a conventional switching device, the tap or auxiliary coil is used to pass the tap or The input terminal of the auxiliary coil reconstructs the connection of the power supply to the filter. Such a zigzag reactor with an additional tap or auxiliary coil, by adjusting the zero phase sequence flux to provide a zero phase sequence impedance for adjusting the zero phase sequence harmonic current filter, can maintain the individual constant In this situation, when changing requirements on the power distribution network are needed, it can be adapted to change the zero phase sequence impedance of the filter without the need for additional external equipment or new equipment designed for customization.

However, such a zigzag filter with an additional tap or auxiliary coil will also change the positive and negative sequence impedance of the filter when the zero phase sequence impedance of the filter is changed by a tap or an auxiliary coil. Therefore, it also inevitably causes the adverse effects of fluctuations in the positive and negative sequence components of the power distribution system.

Therefore, there is a need for other external equipment or a new equipment designed for customization when the system needs to cooperate to change the zero phase sequence impedance of the zero phase sequence filter device; the zero phase sequence filter device Can match the system needs to change the zero phase sequence impedance of the device, and does not affect the positive sequence impedance and negative sequence impedance of the device.

(3) Invention content The present invention is to solve the above-mentioned shortcomings of the prior art, and provides an apparatus and method for zero phase sequence impedance adjustment of a zero phase sequence current filter as a zero with a common end point between a polyphase AC power source and a load. The zero phase sequence impedance of the phase sequence filter does not affect the positive sequence impedance and negative sequence impedance of the zero phase sequence filter.

To achieve the above needs, the present invention provides an apparatus and method for adjusting a zero phase sequence impedance of a zero phase sequence filter having a common terminal between a multiphase AC power source and a load, wherein the apparatus includes a blockage With two ends and one or more taps, an input neutral and an output neutral, the input neutral is connected to the multiphase AC supply, to the output neutral to the load, and zero phase sequence filtering The common endpoint of the device is connected to the input neutral and the output neutral via the occluder; and by changing the tap of the connected occluder to achieve a zero phase sequence impedance of the zero phase sequence filter in parallel with the load .

Because, in a 3-phase 4-wire power distribution system, only zero-phase-sequence current components are present at the common end of the zero-phase-sequence filter, causing only the occluder that is connected to the common endpoint of the zero-phase-sequence filter. There is a zero phase sequence current component; therefore, the zero phase sequence impedance of the zero phase sequence filter connected in parallel with the load can be changed by changing the connection of one tap of the occluder, and only affects the zero phase in the power distribution system. Sequence current component. This kind of transmission control switch changes the tap of the connected occluder in the 3-phase 4-wire power distribution system. For the zero-phase sequence filter connected through the occluder and the neutral line, it is possible to change only the zero phase. The zero phase sequence impedance of the sequence filter does not affect the positive sequence impedance and negative sequence impedance of the zero phase sequence filter.

Further improvement, in various embodiments of the present invention, an additional occluder can be connected in-line between the input of the multi-phase AC power supply and the zero-phase sequence filter; this improvement can increase the neutral line impedance of the power supply. It makes it more difficult to pass the zero-phase sequence current through the distribution transformer to prevent the zero-phase sequence component generated elsewhere in the system from entering the zero-phase sequence filter, and to prevent adverse effects on the system due to improper operation.

Furthermore, the occluder of the present invention can be an inductor and, therefore, consumes little energy and therefore does not adversely affect the efficiency of the system.

While the present invention is being practiced, the invention may be embodied in various other embodiments and various embodiments may be practiced in various embodiments without departing from the details of the invention. The present invention has been made in view of the technical matters. Accordingly, the description and drawings of the invention are intended to be construed (4) Description of the drawings

Figure 1 is a prior art icon to show a zero phase sequence current filter with an adjustable zero phase sequence impedance.

2 is a circuit diagram of a first embodiment of the apparatus and method of the present invention, illustrating the apparatus of the present invention coupled to a typical multi-phase AC power source, a typical zero phase sequence filter with a common terminal and A typical nonlinear load.

Figure 3 is a circuit diagram of a typical zigzag zero phase sequence filter with a common endpoint. Figure 4 is a circuit diagram of a typical wye-delta zero phase sequence filter with a common endpoint. 5 is a circuit diagram of a second embodiment of the apparatus and method of the present invention, illustrating the apparatus of the present invention coupled to a typical multi-phase AC power source, a typical zero-phase sequence filter with a common terminal and A typical nonlinear load.

6 is a circuit diagram of a third embodiment of the apparatus and method of the present invention, illustrating the apparatus of the present invention coupled to a typical multi-phase AC power source, a typical zero-phase sequence filter with a common terminal and A typical nonlinear load.

Figure 7 is a circuit diagram of a fourth embodiment of the apparatus and method of the present invention, similar to the circuit diagram of Figure 2, adding an additional blocker between a polyphase AC power supply and a zero phase sequence filter Enter neutral online.

Main component symbol description

The first coil of the zigzag reactor 3al, 3bl, 3cl

Input terminal of the first coil of the zigzag reactor 13al, 13bl, 13cl

One of the three phases &, b, c

Second coil 3a2, 3b2, 3c2 of the zigzag reactor

Auxiliary coils for zigzag reactors 3a3, 3b3, 3c3

Common endpoint of the zero phase sequence filter N

Taps 13a2, 13b2, 13c2, 13a3, 13b3, 13c3 of the auxiliary coil of the zigzag reactor 30-phase filter 30, 30a

Multiphase AC power supply 10

Nonlinear load 20 Handler 40 with tap

One of the taps of the occluder 42a, 42b 42c, 42d

One of the two ends of the occluder is 401, 402

Control switch 50

Contacts 301a, 301b, 301c

Input neutral 101

Output neutral line 102

Enter the extra damper for the neutral 60

(5) Specific implementation methods

The apparatus and method for zero phase sequence impedance adjustment of the zero phase sequence current filter of the present invention is suitable for adjusting the zero phase sequence current of a multi-phase AC power source and a neutral line in a multi-phase AC power distribution system. The apparatus and method of the present invention adjusts the zero phase sequence impedance of a zero phase sequence filter with a common endpoint between a polyphase AC power source and a load, and does not affect the positive sequence impedance and negative sequence of the zero phase sequence filter impedance.

2 is a circuit diagram embodying a first embodiment of the apparatus and method of the present invention to illustrate that the apparatus of the present invention is coupled to a typical multi-phase AC power supply, a typical zero phase sequence filter having a common terminal With a typical nonlinear load. Figure 3 is a circuit diagram of a typical zigzag zero phase sequence filter 30 with a common endpoint. Figure 4 is a circuit diagram of a typical wye-delta zero phase sequence filter 30a with a common endpoint. The zero phase sequence filter with common end points in FIG. 2 may be a zigzag reactor 30 as shown in FIG. 3, or may be replaced by a wye-delta zero phase sequence filter 30a as shown in FIG. A zero phase sequence filter 30 with a common endpoint in 2. In FIG. 2, the zero phase sequence filter 30 is coupled to a polyphase AC power source 10 and a non-linear load 20 via contacts 301a, 301b, 301c; and the common terminal N of the zero phase sequence filter 30 is coupled to an occluder One of the two ends of the 40 points 401, and is connected to the aforementioned input neutral line 101 via a control switch 50 via a tap (42a or 42b or 42c or 42d) of the occluder or the other end 402 of the two ends The aforementioned output neutral line 102.

In the circuit diagram of Figure 2, only zero-phase-sequence current components appear at the common endpoint of the zero-phase-sequence filter, causing zero-phase-sequence current on the occluder connected to the common endpoint of the zero-phase-sequence filter. Therefore, the following description is taken as an example to change a tap of the occluder 40 by controlling the switch 50. The connection of the occluder connecting the control switch from the original tap 42a to the component tap 42b will result in an equivalent zero phase of the zero phase sequence filter connected to the non-linear load through the occluder 40 in parallel with the output neutral. The change in the order impedance increases and only affects the zero phase sequence current component in the circuit diagram. This operational effect will result in an equivalent zero phase sequence impedance of the zero phase sequence filter connected in parallel with the load, without affecting the positive sequence impedance and negative sequence impedance of the zero phase sequence filter.

This makes it possible to replace the original device with a custom-designed zig-zag filter, especially in the case of special system requirements. Just change the tap of the occluder connected to the control switch according to the system requirements, and change the zero phase sequence impedance of the device to meet the needs of the system.

5 is a circuit diagram of a second embodiment of the apparatus and method of the present invention, illustrating the apparatus of the present invention coupled to a typical multi-phase AC power source, a typical zero-phase sequence filter with a common terminal and A typical nonlinear load. In the figure, the zero-phase sequence filter 30 is connected between a multi-phase AC power source 10 and a non-linear load 20 via contacts 301a, 301b, 301c; and an input neutral line 101 and an output neutral line 102 are connected to One end 401 of the occluder 40 is clicked and connected to the zero phase sequence filter 30 via a control switch 50 via a tap (42a or 42b or 42c or 42d) of the occluder or the other end 402 of the two end points. Common endpoint N.

6 is a circuit diagram of a third embodiment of the apparatus and method of the present invention, illustrating the apparatus of the present invention coupled to a typical multi-phase AC power source, a typical zero-phase sequence filter with a common terminal and A typical nonlinear load. In the figure, the zero phase sequence filter 30 is connected between a polyphase AC power source 10 and a non-linear load 20 via contacts 301a, 301b, 301c; and the common terminal N of the zero phase sequence filter 30 is connected to the occluder 40. One of the two end points 401, and the other end point 402 of the two ends of the occluder are connected to an input neutral line 101, and connected via a control tap 50 via a tap (42a or 42b or 42c or 42d) of the occluder Up to the output neutral line 102.

The second embodiment and the third embodiment can also be exemplified as the first embodiment, by controlling the switch 50 to change the connection of a tap of the occluder 40, so that the occlusion device and the output neutral line are The equivalent zero-phase sequence impedance of a zero-phase-sequence filter with linear loads connected in parallel affects only the zero-phase-sequence current components in the circuit diagram.

Figure 7 is a circuit diagram of a fourth embodiment of the apparatus and method of the present invention, similar to Figure 2 An additional blocker 60 is added to the input neutral 101 between the aforementioned polyphase AC power source 10 and the aforementioned zero phase sequence filter 30 to suppress zero phase sequence components generated elsewhere in the system from entering the zero phase. Sequence filter. Furthermore, the second embodiment and the third embodiment are also exemplified as the fourth embodiment, adding an additional occluder to the aforementioned input neutrality between the aforementioned multi-phase AC power source and the aforementioned zero-phase sequence filter. Online (not shown).

In actual operation, the embodiments may be exemplified as in the first embodiment, and the zero phase sequence filter of each embodiment is used as needed, and the zigzag zero phase sequence filter 30 or the wye-delta zero phase sequence filter is used. 30a.

The various embodiments described above are illustrative of the invention, but the invention is not limited by the embodiments. In this disclosure, only a few of the various examples of the invention are shown and described. The invention can be applied to a wide variety of other combinations and environments, and can be varied or modified without departing from the spirit and scope of the invention.

Claims

Claim

1. A zero phase sequence impedance adjustment device for a zero phase sequence current filter as a zero phase sequence impedance for adjusting a zero phase sequence filter with a common terminal between a multiphase AC power source and a load, the device An occluder having two end points and one or more taps, an input neutral line and an output neutral line, the aforementioned input neutral line being connected to the aforementioned multi-phase AC power source, the aforementioned output neutral line connection To the aforementioned load, the common end point of the aforementioned zero phase sequence filter is connected to the aforementioned input neutral line and the aforementioned output neutral line via the aforementioned occluder; and by changing the connected taper of the aforementioned occluder The means is to achieve a zero phase sequence impedance of the aforementioned zero phase sequence filter in parallel with the aforementioned load.

2. The apparatus according to claim 1, wherein the common endpoint of the aforementioned zero-phase sequence filter is connected to the aforementioned input neutral line and the aforementioned output neutral line via the aforementioned occluder, which may be the zero phase sequence A common end of the filter is coupled to one of the two end points of the occluder and is coupled to the aforementioned input neutral line and the aforementioned output neutral line via one of the tap or one of the two ends.

3. The apparatus according to claim 1, wherein the common end point of the aforementioned zero phase sequence filter is connected to the aforementioned input neutral line and the aforementioned output neutral line via the aforementioned occluder, which may be the zero phase sequence filtering. The common end of the device is connected to one of the taps or the two ends of the occluder and is connected to the aforementioned input neutral and the aforementioned output neutral via one of the two ends of the occluder.

4. The apparatus according to claim 1, wherein the common end point of the aforementioned zero phase sequence filter is connected to the aforementioned input neutral line and the aforementioned output neutral line via the aforementioned occluder, which may be the zero phase sequence a common end of the filter is connected to one of the two ends of the occluder, and the other end of the occluder is connected to the aforementioned input neutral and connected to the aforementioned via a tap of the occluder The output of the neutral line.

A device as claimed in claim 1, wherein said input neutral between said multiphase AC power source and said zero phase sequence filter is connected in series with an additional occluder.

6. Apparatus according to claim 1 wherein said zero phase sequence filter is a multiphase zigzag reactor or autotransformer.

7. Apparatus according to claim 1 wherein said zero phase sequence filter is a multiphase YWE-DETA wired transformer.

8. A method of zero phase sequence impedance adjustment of a zero phase sequence current filter as an adjustment in a multiphase AC

Correction page (Article 91) A zero phase sequence impedance of a zero phase sequence filter with a common endpoint between the power supply and a load, the steps comprising: providing an occluder with two ends and one or more taps, an input neutral, and an output a neutral line; the aforementioned input neutral line is connected to the aforementioned multi-phase AC power source;

The aforementioned output neutral line is connected to the aforementioned load; and

In order to change the zero phase sequence impedance of the aforementioned zero phase sequence filter in parallel with the aforementioned load, by changing the common end point of the zero phase sequence filter, the aforementioned input neutral line and the aforementioned output neutral line The means of connecting the aforementioned occluder taps is achieved.

9. The method of claim 8 wherein said input neutral between said multiphase AC power source and said zero phase sequence filter is coupled to an additional occluder.

Correction page (Article 91)