JPH067531B2 - Winding arrangement of three-winding transformer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a three-winding transformer, such as a transformer for a load tap switching rectifier or an electric furnace, which contains a lot of harmonic components in a load current of a secondary winding. Winding arrangement of the container.

[Prior art and its problems]

In this type of transformer, the load current contains many harmonic components because the disturbance of the waveform on the load side is large.
In order to prevent the high-frequency current flowing in the secondary winding from flowing into the AC power supply system via the primary winding and causing high-frequency interference in other system equipment, an LC absorption harmonic filter is installed on the tertiary winding side. The measures to be installed are generally taken.

FIG. 2 is a single-wire connection diagram of a three-winding transformer for a rectifier equipped with an indirect switching type load tap changer on the secondary winding side (DC winding side). It is composed of a primary winding 1, a secondary winding 2, a tertiary winding 3, and a tap winding 5 provided with a polarity switcher 4, which are wound like a coil. The output voltage of the tap winding 5 is a series transformer 6. The output voltage of the secondary winding 2 is adjusted via the output voltage of the secondary winding 2, and the voltage of the load circuit connected between the terminals u and v can be controlled. Is provided.

By the way, the harmonic current generated in the secondary winding 11 including the tap winding 5 of the transformer configured as shown in FIG. 2 flows out to the primary winding 1 and the tertiary winding 3 sides between the windings. It depends on the leakage impedance (or impedance voltage) of.

FIG. 3 is a symbolic view of a three-winding transformer, which is a three-terminal circuit including a primary winding 1, a secondary winding 11 including a tap winding, and a tertiary winding 3 which are magnetically coupled to each other. P, S, T
In the three-winding transformer represented by, if the leakage impedance between the windings converted to the reference capacity (usually the primary capacity) is eps, est, etp, the impedance separated in each winding is the equivalent circuit shown in Fig. 4. Can be expressed as follows, and the separated primary winding impedance ep, secondary winding impedance es, and tertiary winding impedance
et can be expressed by the following equation.

By the way, as a method of enhancing the absorption effect of the LC filter 7 for absorbing harmonics arranged on the output side of the tertiary winding 3,
Conventionally, there is known a measure for minimizing the separation impedance et of the tertiary winding in the equivalent circuit of FIG.

FIG. 5, FIG. 6, and FIG. 7 are winding arrangement diagrams in the prior art. Main winding 1 → tap winding 5 → tertiary winding 3 → from the leg side of iron core 10 toward the outer circumferential side in order. The winding arrangement of FIG. 5 arranged in the order of the secondary winding 2, the winding arrangement of FIG. 6 arranged in the order of 5 → 1 → 3 → 2, arranged in the order of 1 → 3 → 5 → 2 In any of the winding arrangements of FIG. 7, the separation impedance et of the tertiary winding 3 can be set to almost zero or a negative value. However, in the conventional winding arrangement shown in FIG. 5 to FIG. 7, the secondary winding 2, the tap winding 5 and the tertiary winding 3 whose voltage is changed by switching the taps are adjacent to each other. In addition, the separation impedance et of the tertiary winding changes with the switching of the taps, and the harmonic absorption filter 7 does not function sufficiently at the tap selection position where the separation impedance becomes large. There is a problem that current flows out, and in order to improve this, a harmonic absorption filter may have to be installed in the primary winding (high voltage side), which has the disadvantage of making the filter large and expensive. It was

[Object of the Invention]

The present invention has been made in view of the above-mentioned situation, and can keep the separation impedance et of the tertiary winding near zero regardless of the tap selection position, and thus can absorb the harmonic absorption arranged on the tertiary winding side. It is an object of the present invention to provide a winding arrangement structure of a three-winding transformer that can highly demonstrate the performance of a filter.

[Main points of the invention]

According to the present invention, a tertiary winding is separately formed into a first tertiary winding and a second tertiary winding, and the first tertiary winding, the primary winding, the second tertiary winding, from the iron core leg side toward the outer peripheral side, The tap winding and the secondary winding are arranged concentrically in this order, and the harmonic absorption filter is connected to the series body of the first and second tertiary windings. It becomes possible to reduce the change of the separation impedance of the tertiary winding, and the number of turns distribution of the first and second tertiary windings can be distributed between the primary winding and the tertiary winding with respect to the secondary winding including the tap winding. By pre-setting the impedance changes due to tap switching of line impedance to be equal to each other, the separation impedance of the tertiary winding can be kept constant with respect to that of the primary winding regardless of tap position.

Example of Invention

 The present invention will be described below based on an embodiment.

FIG. 1 is a schematic side sectional view of an essential part showing a winding arrangement of a transformer of an embodiment of the present invention, and shows an application example to a three-winding transformer for a rectifier shown in FIG. In the figure, iron core 1
From the leg side of 0 toward the outer peripheral side, the first tertiary winding 8, the primary winding 1, the second tertiary winding 9, the tap winding 5, and the secondary winding 2 are concentric with each other and necessary. L and C type harmonic absorption filter is provided at the line end of the tertiary winding 13 which is wound with a large insulation distance and is made up of a series connection body of the first tertiary winding 8 and the second tertiary winding 9. 7 is conductively connected. By configuring the winding arrangement as described above, the tap winding 5
And a secondary winding 2, and a load current containing a large amount of harmonic components flows, and is arranged opposite to a secondary winding 12 in which the distribution of leakage magnetic flux containing a harmonic component changes due to tap switching. The second tertiary winding 9 is directly affected by the leakage magnetic flux generated by the secondary winding 12, and the separation impedance et is likely to change at the time of tap switching, but the first tertiary winding 8 has a small change in the separation impedance ep. By arranging in the shadow of the primary winding 1, the influence of the leakage magnetic flux of the secondary winding 12 is reduced, and the change of the separation impedance due to tap switching can be suppressed. Therefore, the separation impedance et as the whole of the tertiary winding 13 composed of the series body of the first and second tertiary windings is determined by the average value of the separation impedances of the first tertiary winding 8 and the second tertiary winding 9, respectively. The average value can be controlled by changing the winding number distribution of the first and second tertiary windings 8 and 9.

Further, in the above formula (1), the inter-winding impedance changes due to the tap switching, since only eps and est including the separation impedance es of the secondary winding 12 are present. By presetting the winding number distributions of the first and second tertiary windings 8 and 9 so that the change amounts of est are equal to each other, the average of the tertiary winding 13 with respect to the separation impedance ep of the primary winding 1 is set. It is possible to always keep the separation impedance et constant. As a result, the ratio of the harmonic current absorbed by the harmonic absorption filter 7 provided at the line end of the tertiary winding 13 to the harmonic current flowing out to the AC power source side via the primary winding 1 is the tap position. The problem of changing due to

〔The invention's effect〕

As described above, the present invention divides the tertiary winding into the first tertiary winding and the second tertiary winding on the basis of the predetermined number of turns distribution, and the first tertiary winding from the iron core leg side toward the outer peripheral side, Primary winding,
The second tertiary winding, the tap winding, and the secondary winding are arranged concentrically in this order, and harmonics are absorbed at the line end of the tertiary winding that is a series connection of the first and second tertiary windings. A filter is provided. As a result, the second tertiary winding, which is easily affected by the leakage magnetic field distribution that changes depending on the tap position generated by the secondary winding including the tap winding, and the influence of the leakage magnetic field distribution, which is arranged behind the primary winding. It is possible to obtain a first tertiary winding that is difficult to receive, and to control the average separation impedance of the first and second tertiary windings to maintain a constant value by adjusting the winding number distribution of both tertiary windings. As a result, the harmonic current absorption performance of the harmonic absorption filter deteriorates depending on the tap position, and the harmonic current flowing out to the AC power supply side via the primary winding increases, causing harmonic interference. It is possible to provide a three-winding transformer provided with a winding arrangement structure capable of eliminating the technical problems and thus highly exhibiting the performance of the harmonic absorption filter. Further, since it is unnecessary to dispose the harmonic absorption filter on the primary winding (high voltage side), there is an advantage that the harmonic absorption filter can be formed in a small size and at a low cost.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of an essential part showing a winding arrangement of a transformer of an embodiment of the present invention, FIG. 2 is a single wire connection diagram showing an example of a three-winding transformer for a rectifier, and FIG. 3 is a wiring diagram of the three-winding transformer, FIG. 4 is an equivalent circuit diagram of the three-winding transformer with impedance separation, and FIGS. 5 to 7 are schematic side cross-sectional views showing the winding arrangement in the prior art. Is. 1 ... Primary winding, 2 ... Secondary winding, 3 ... Tertiary winding, 5 ... Tap winding, 6 ... Series transformer, 7 ... Harmonic absorption filter,
8 ... 1st tertiary winding, 9 ... 2nd tertiary winding, 10 ... Iron core, 1
1, 12 ... secondary winding, 13 ... tertiary winding.

Claims (1)

[Claims] Claim: What is claimed is: 1. A primary winding, a secondary winding of a voltage adjusting system under load including a tap winding, and a tertiary winding equipped with a harmonic absorption filter are concentrically wound around a leg portion of an iron core. In the transformer described above, the number of winding turns is set so that impedance variations between the primary winding and the tertiary winding with respect to the secondary winding including the tap winding by tap switching are equal to each other. The first tertiary winding and the second tertiary winding are connected in series, and each winding is a first tertiary winding, a primary winding, and a second tertiary winding from the core leg side toward the outer peripheral side. , A tap winding, and a secondary winding are arranged concentrically with each other in this order, and a harmonic absorption filter is provided at the line end of the tertiary winding formed of a series connection body of the first tertiary winding and the second tertiary winding. Is a three-winding transformer characterized by being electrically connected. Vessels of the winding arrangement.