JPH0212007B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to the winding arrangement and connection of a direct switching type on-load tap-change transformer in which a primary winding and a secondary winding are connected by a single turn. .

[Prior art and its problems]

Since this type of transformer is used by connecting to an ultra-high voltage, large capacity power transmission line, there is a need for an increase in the transportable capacity of the unit as well as a reduction in size and weight.

FIG. 1 is a winding layout diagram of a conventional on-load tap switching autotransformer, which is manufactured as a single-phase transformer, connected in a three-phase bank at the installation site, and used as a three-phase transformer. In the figure, a tertiary winding 3, a tap winding 5, a shunt winding 2, and a series winding 1 are wound concentrically around the main leg portion 9A of the iron core 9 in order from the inside so as to maintain a predetermined insulation gap. The series winding 1 and the shunt winding 2 are connected by a single turn, and the tap winding 5 has a large number of tap leads 5A, 5.
B is connected in cascade to, for example, a shunt winding via a switching circuit such as an on-load tap changer (not shown), thereby forming a single-phase single-turn on-load tap changer transformer. However, in a structure where many windings are arranged concentrically on one core leg as shown in the figure, the maximum outer diameter of the windings is
D ₁ increases, resulting in an increase in the transportation width dimension of the transformer, which limits the transportable capacity of the single unit.In addition, the lead wires 5A and 5B drawn out from the tap winding 5 are high-voltage series windings. line 1 and shunt winding 2
Since the lead wires 5A and 5B cross the upper and lower ends of the lead wires, the arrangement and insulation structure of the lead wires 5A and 5B become complicated.

FIG. 2 is a winding layout diagram of an improved conventional single-phase single-turn load tap switching transformer, and FIG. 3 is an expanded winding layout and connection diagram. In the figure, the main leg side excitation winding 4, the shunt winding 2, and the series winding 1 are wound concentrically with each other in order from the inside on the main leg portion 9A of the iron core 9, and the return leg 9B of the iron core 9 A return leg side excitation winding 6, a tertiary winding 3, and a tap winding 5 are wound concentrically with each other on one side of the winding, in order from the inside. In addition, as shown in Figure 3, the windings are connected to each other by connecting the series winding 1 and the shunt winding 2 in a single-turn connection (series connection), with the high-voltage line terminal U and medium-voltage (shunt) terminal U drawn out. At the same time, a tap winding 5 is connected to the neutral point side of the shunt winding 2.
are connected in cascade, and the tap changer 7 of the tap changer circuit 7 consists of the polarity changer 7A and the tap changer 7B.
A neutral point terminal O is drawn out through B. In addition, the main leg side excitation winding 4 and the return leg side excitation winding 6, which are magnetically coupled to the shunt winding 2, are connected in parallel inside the transformer to excite the power supplied from the shunt winding 2. The load current is received by the excitation winding 6 via the winding 4, and the received power flows into the tertiary winding 3 and the tap winding 5.
The circuit is configured to supply the load current corresponding to the load current flowing through the circuit. The three single-phase autotransformers configured in this way have their neutral terminals O connected to each other and grounded at the installation site, forming a star-connected three-phase autotransformer bank. , one of the line end U side and the shunt end U side is connected to a three-phase power supply and the other to a three-phase load. As mentioned above, the tap winding 5 and the tertiary winding 3 are connected to the main leg 9A using the return leg 9B of the iron core.
By separating it from the side, even if we add the newly required excitation winding 4, the number of windings on the main landing gear side is reduced to 4 as shown in Figure 1.
Since the winding is reduced to 3 windings, the maximum winding outer diameter
D2 can be reduced compared to D1 in FIG. In addition, since it can be arranged outside the winding of the return leg of the tap winding 5, the lead wires 5A and 5B can be easily drawn out.
Moreover, if the tap changer 7 is arranged on the side of the tap winding 5, there is an advantage that the structural arrangement of the lead wires can be simplified. However, since the windings are wound on both the main leg side and the return leg side, there is a drawback that the dimension of the iron core in the transportation length direction increases. In particular, in order to further increase the transport capacity, when the main landing gear side winding or the return leg side winding is divided to wind multiple main landing gears or return legs, the length of the transport becomes larger. This poses a problem in that it hinders the increase in transport capacity.

Figures 4 to 6 are circuit diagrams showing the current flow in the conventional structures shown in Figures 2 and 3, with Figure 4 at the highest tap, Figure 5 at the intermediate tap, and Figure 6 at the lowest tap. The flow of current at each time is indicated by a solid arrow. In FIG. 4, at the highest tap, the tap changer 7B is connected to the highest tap a of the tap winding 5, and the polarity changer 7A is connected to the lowest tap C side of the tap winding 5, so that the shunt side output terminal The load current supplied to the load via u is passed from the neutral point O side to tap a, tap winding 5, polarity switch 7A, and shunt winding 2 via transformers of other phases connected in a three-phase bank. As a result, the sum of the voltages of the shunt winding 2 and the tap winding 5 is generated at the u terminal. However, since the tap winding 5 is wound on the return leg side,
When the load current flows through the tap winding 5, a current for balancing the magnetomotive force generated in the tap winding also flows in the two excitation windings 4 and 6, so that the losses caused by these currents are reduced. Tap winding 5
There is also a problem that the loss occurs in the excitation windings 4 and 6, respectively, and the loss generated in the transformer increases.
Even at the intermediate tap in Fig. 5, the polarity switch 7
A is connected to the a tap, and a tap changer is connected to the b tap, for example, so that the a,
Since the load current flows between the b taps, losses due to this load current occur in the windings 4, 5, and 6, as in the case of the maximum tap described above. Furthermore, at the lowest tap in Figure 6, the same loss occurs in tap winding 5 and excitation windings 4 and 6 as in Figure 4, only the direction of the current is different from that at the highest tap in Figure 4. .

[Purpose of the invention]

The present invention was made in view of the above-mentioned situation, and
The object of the present invention is to provide a single-phase or three-phase tap-change autotransformer on load that is small and lightweight and generates little loss.

[Key points of the invention]

In the transformer of the present invention, the tap winding that also serves as the excitation winding is placed on the return leg side of the main transformer in the case of a single-phase transformer, and the magnetic path is different from that of the iron core of the main transformer in the case of a three-phase transformer. The tap winding is connected in parallel to the excitation winding, which is provided on the main leg side of the iron core and is wound on the main leg of the main transformer concentrically with the series winding and the shunt winding. By configuring the shunt winding and the tap winding to be connected in a single turn, one excitation winding is omitted and the generated loss is reduced.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 7 is a winding arrangement and connection diagram of a transformer showing an embodiment of the present invention, and shows an example of a single-phase transformer. In the figure, 9A and 9B indicate the main leg and return leg of the core 9 of the main transformer, respectively. A series winding 1 is wound thereon. Further, the return leg 9B of the iron core 9 includes a tap winding 15 that also serves as an excitation winding, and a tertiary winding 3 provided as necessary.
are wrapped concentrically. In addition, the connection between the windings is such that the series winding 1 and the shunt winding 2 are connected as single windings, and the high voltage line terminal U and medium voltage (shunt) line terminal U are respectively drawn out, and the shunt winding 2 is connected with a single winding. The neutral point side is connected to the tap winding 15 via the polarity switch 7A of the direct tap switching circuit 7, and the tap winding 15 is connected to the neutral point terminal O via the tap switching device 7B of the direct tap switching circuit 7. has been done. Further, the excitation winding 4 and the tap winding 15 are connected in parallel to each other.
A transformer constructed in this manner consists of a series winding 1, a shunt winding 2, and a tap winding 3, which are connected in series by connecting the neutral terminals O of three transformers in parallel at the installation site. The main winding circuit is star-wired. Furthermore, if the excitation winding 4 is configured to be connected in delta when three-phase bank connection is made, the zero-sequence magnetic flux that induces the third harmonic voltage can be absorbed, so it is necessary to provide a tertiary winding connected in delta as a stable winding. There isn't. According to the embodiment described above, the excitation winding 6 is omitted by configuring the tap winding 15 to also serve as the excitation winding 6 on the return leg side in the conventional structure shown in FIG. 2 or 3. As a result, the maximum outer diameter of the winding on the return leg side can be reduced from the dimension D2 in Figure 2, and therefore the dimension in the transport length direction of the transformer can be reduced, and the transformer can be made lighter. can be converted into

Figures 8 to 10 are circuit diagrams for explaining the current flow in the embodiment shown in Figure 7, with Figure 8 at the highest tap, Figure 9 at the intermediate tap, and Figure 10 at the lowest tap. The direction and path of the load current in is indicated by the dashed arrow. First, the load current shown by the broken line arrow in FIG. 4 flows from the shunt side line terminal U through the load (not shown) to the tap winding 15 side via the neutral point terminal O, but at the maximum tap, the polarity switch 7A is connected to the lowest tap position C side, the tap changer 7B is connected to the highest tap position a side, and the main landing gear side excitation winding 4 is connected between a and C in parallel with the tap winding 15. Then, the load current flows from the neutral terminal O to the shunt winding 2 via the tap switch 7B, the excitation winding 4, and the polarity switch 7A. Therefore, since no load current flows through the tap winding 15, no loss occurs, and the generated loss can be reduced compared to FIG. 4. The same applies to the lowest tap in FIG. On the other hand, as shown in FIG.
is connected to the intermediate tap position b of the polarity switch 7A.
At the intermediate tap when the tap is connected to the highest tap position a, the excitation winding 4 is connected in parallel to both ends a-C of the tap winding 15, and the tap b-C in FIG.
In order to avoid the generation of idle coils, the current flowing between a and C of the tap winding 15 via the excitation winding 4 is divided from the neutral point O through b and C of the tap winding. The current flowing into the tap winding 15
The directions between b and C are opposite to each other, and the tap winding 1
5, the load current flowing between b and C decreases. That is, the tap winding 15 is a series winding between a and b, and a series winding between a and b.
The current flowing between b and C of the tap winding, which is the common winding, can be reduced, and therefore the tap winding It is possible to reduce the generated loss.

As mentioned above, the loss generated in the embodiment shown in FIG. 7 is reduced due to the removal of the return leg side excitation winding 6 and the tap winding compared to the conventional structure shown in FIG. 2 or 3. By connecting the wire 15 and the excitation winding 4 in parallel, the loss is reduced by the double reduction effect of the tap winding functioning as a single-turn connected winding. Ru.

FIG. 11 is a connection diagram showing a different embodiment of the present invention. In the figure, a series winding 1, a shunt winding 2, and an excitation winding 4 are concentrically wound on the main leg 9A side of the iron core, and an excitation winding 25 and a tertiary winding 3 on the return leg 9B side. The tap windings 25 are wound concentrically in the same manner as in the embodiment shown in FIG. The winding 1 and the shunt winding 2 are connected in cascade, and the high voltage (series)
The difference is that the voltage at the side line end U is configured to be adjusted. In this embodiment, tap winding 2
5 and the ground insulation of the direct tap switching circuit must be able to withstand the ground voltage of the medium voltage (shunt) side line end u, but the excitation winding 6 on the return leg side is no longer required and the loss associated with it is The same reduction effect as in the embodiment shown in FIG. 7 can be obtained.

FIG. 12 is a connection diagram showing still another embodiment of the present invention, and the difference from the embodiments of FIGS. 7 and 11 is that the tap winding 25 is connected via a polarity switch 27A and a tap switch 27B. By connecting between the line terminal u on the voltage (shunt) side and the connection point M of the series winding 1 and the shunt winding 2, the output voltage of the line terminal u on the medium voltage (shunt) side is adjusted. be able to.

FIG. 13 is a winding arrangement and connection diagram showing another embodiment of the present invention, and shows an example of a three-phase autotransformer. In the figure, 10 is a three-phase single-winding main transformer, and each of the three main legs of the iron core has three series windings for three phases.
1. The shunt winding 32 and the excitation winding 34 are wound concentrically for each phase, and the series winding 31 and the shunt winding 32 are connected in a single turn to the high voltage side line terminals U, V, W and Medium-voltage side line terminals u, v, and w are drawn out.
Further, 20 is a separately installed series transformer, and tap windings 35 are wound around each of the three legs of the iron core. An excitation winding 34 provided on the main transformer 10 side and a tap winding 35 provided on the series transformer side.
are connected in parallel for each phase, the shunt winding 32 and the tap winding 35 are connected in cascade through a polarity switch 37A, and the tap winding is connected in a star shape through a tap switch 37B. , the neutral point terminal O is pulled out. Tap winding 35 as described above
is wound around the core of the series transformer 20 whose magnetic path is different from that of the core of the main transformer 10, the excitation winding on the series transformer 20 side can be omitted. It can be configured to be small and lightweight, and the loss generated by the series transformer can be reduced.

Although FIG. 13 shows an example of a transformer with a single winding connection, it is obvious that the present invention can also be applied to a transformer in which a high voltage winding and an intermediate voltage winding are separated.

〔Effect of the invention〕

As described above, the present invention utilizes the return leg of the iron core in the case of a single-phase converter, or by providing a series transformer in the case of a three-phase converter to connect the tap winding to the return leg or the series transformer. Tap winding is achieved by connecting the tap winding in parallel with the excitation winding, which is wound around the iron core and is also wound concentrically with the series winding and the shunt winding around the main legs of the main transformer iron core. The structure is such that the wire also serves as an excitation winding. As a result, the excitation winding that was conventionally installed on the return leg side or the series transformer is no longer necessary, and by omitting the excitation winding, the weight of the winding is reduced, and the outer diameter of the tap winding and the core window area (magnetic Since the path length can be reduced, the transformer can be made even smaller and lighter. Furthermore, by reducing the core window area, the transportation length of the transformer can be shortened. In this way, it is possible to provide a tap-switching autotransformer that is smaller and lighter than conventional structures, and the transportable capacity of single units can be increased as needed, making it possible to increase the voltage and capacity of transmission and substation systems. It can contribute to economically advantageous development.

In addition, from the perspective of reducing the loss generated by the transformer, it is possible to reduce the generated loss by omitting the excitation winding, and by connecting the tap winding and the excitation winding in parallel, the tap winding can be connected to the load current. On the other hand, since it can function as an autotransformer, the loss generated by the tap winding can also be reduced. Therefore, it is possible to provide an on-load tap switching autotransformer that generates less loss than the conventional structure.

[Brief explanation of drawings]

Figure 1 is a winding layout diagram of a conventional on-load tap-changing transformer, Figure 2 is a winding layout diagram of an improved conventional transformer, and Figure 3 is a winding layout and connection of the transformer shown in Figure 2. 4 to 6 are circuit diagrams showing the flow of load current in the transformer of FIG. 2, and FIG. 7 is a winding of a single-phase load tap-change autotransformer showing an embodiment of the present invention. 8 to 10 are circuit diagrams showing the flow of load current in the embodiment of FIG. 7, FIG. 11 is a transformer connection diagram showing a different embodiment of the present invention, and FIG. 12 is a circuit diagram showing the flow of load current in the embodiment of FIG. FIG. 13 is a wiring diagram of a transformer showing another embodiment of the present invention. FIG. 13 is a winding arrangement and connection diagram of a three-phase load tap switching autotransformer showing another embodiment of the present invention. 1, 31... Series winding, 2, 32... Shunt winding, 3... Tertiary winding, 4, 34... Main leg side excitation winding, 5... Tap winding, 6... Return leg Side excitation winding, 5A, 5B...Tap pullout lead, 7...
Direct tap switching circuit, 7A, 27A, 37A...
Polarity switch, 7B, 27B, 37B...Tap switch, 9...Iron core, 9A...Main leg, 9B...Return leg, 15, 25, 35...Tap winding that also serves as excitation winding , 10...main transformer, 20... series transformer.

Claims (1)

[Claims] 1. A series winding, a shunt winding, and an excitation winding concentrically wound around the main leg of the iron core of the main transformer, and the return leg of the iron core or the iron core are connected to a magnetic path. A direct tap switching circuit consisting of a tap winding wound around the legs of an iron core with different angles, and a polarity switch and a tap switch connected to the tap winding, the excitation winding and the tap winding being are connected in parallel, and the tap winding is connected in cascade via the direct tap switching circuit to the single winding circuit consisting of the series winding and the shunt winding. winding transformer. 2. In what is stated in claim 1,
An on-load tap switching autotransformer characterized in that the main transformer is a single-phase transformer, and the tap winding is wound around the return leg of the iron core of the main transformer. 3 In what is stated in claim 1,
An on-load tap switching autotransformer characterized in that the main transformer is a three-phase transformer, and the tap windings are wound around the legs of the iron core of the series transformer. 4 In what is stated in claim 1,
Tap switching during load, characterized in that the tap winding is cascade-connected to the neutral point side of the shunt winding via a polarity switch, and the neutral terminal is drawn out via the tap switch. Autotransformer. 5 In what is stated in claim 1,
An on-load tap switching autotransformer characterized in that a tap winding is cascade-connected between a series winding and a shunt winding via a polarity switch and a tap switch. 6 In what is stated in claim 1,
The tap winding is characterized in that one end is connected to a cascade connection between the series winding and the shunt winding, and the other end is connected to a line end terminal of the shunt winding through a direct tap switching circuit. Tap-change autotransformer when loaded.