JPS5850011B2 - transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transformer with dual voltage rating.
The objective is to provide an economical transformer that can easily and rationally switch between the dual voltage ratings, even in high voltage, large capacity transformers.

The transmission voltage at a newly constructed power plant or substation, etc.
It is originally related to the power demand required for the power system. For example, for the time being, the power transmission voltage is 275KV, and it is connected to the surrounding existing power system, and in the future, when the power demand increases, the voltage can be increased to 550KV. However, plans are often made to connect it to new ultra-super high voltage systems.

If the transformers installed in such power generation and substations have dual voltage ratings, they can be used without replacing the transformers even when the voltage changes in the future, which is very economical.

On the other hand, even in the existing substation, the transformer that was receiving power at 154KV was replaced with a larger transformer due to the increase in transformer capacity, and the existing transformer was now used for receiving 77KV power, and a separate substation was installed. There may also be cases where the system is relocated and reused, and a dual voltage rated transformer is still required.

Figures 1a and 1b are examples of the winding arrangement of the most typical conventional dual voltage rated transformer.

This is constructed by winding a low-voltage winding around an iron core 1 and high-voltage winding units 11 and 12 divided equally into two groups. When connected in parallel and at high voltage, high voltage winding units 11 and 12
are connected in series to obtain twice and half the voltage respectively.

Note that the arrow in the winding unit indicates the direction of the induced voltage.

Although this wiring system is simple and easy to change connections, as can be seen from Figure 1a, the voltage between the high voltage line terminals is always applied to the gap between the high voltage winding units 11 and 12. It can only be applied to transformers of up to 77/154KV class due to insulation.

Therefore, for higher voltage class transformers, high voltage winding units 13 and 14 are required, as shown in Figures 2a and b.
There is an example in which double or half voltage is obtained by arranging them concentrically and switching them in series and parallel.

Although this arrangement is suitable for high voltage class windings, when connected in parallel as shown in Figure 2a, almost all of the current flows to the high voltage winding unit 13 due to the impedance between the windings. It does not flow into unit 14.

Therefore, if the transformer capacity remains unchanged at each voltage in the dual voltage rating, the high voltage winding unit 13 would originally only need half the capacity of the low voltage winding, but for the reasons mentioned above, the full capacity is required. It becomes.

In the case of the series connection shown in FIG. 2, the current in the high-voltage winding unit 13 is, of course, half that of the case shown in FIG. 2a.

Therefore, in the examples shown in Figures 2a and b, the high voltage winding units 13 and 140 have a winding capacity that is 1.5 times that of the low voltage winding (-1,
0+0.5), which has the disadvantage of significantly increasing the size of the transformer.

Furthermore, as can be seen from the ampere frequency distribution diagrams in Figures 3a and 3b, the inter-winding leakage impedance increases significantly in the case of Figure 2A compared to the case of Figure 2A, so
Unfavorable for system operation.

Figures 4a and 4b are initially constructed as a normal transformer as shown in Figure 4a, and are made from an iron core 2, a high voltage winding 16, and a low voltage winding 21 that have the voltage capacity necessary for future voltage increases. Figure 4 shows a conventional example in which a transformer is installed and wired as shown in Figure 4.

This method is flexible in changing the voltage value because it is not restricted by the rising voltage value.However, if the transformer capacity remains unchanged when changing the voltage, on the side base of Fig. 2, The utilization rate of the initial transformer capacity becomes poor, and furthermore, the increase in size due to the construction of two transformers becomes extremely uneconomical.

The present invention has been made in view of the above circumstances, and provides an economical double voltage rated transformer that can be easily and rationally switched even at ultra-high voltage or ultra-super high voltage and large capacity. The purpose is to provide

An embodiment of the present invention will be described below with reference to the drawings.

In Figures 5a and 5b, the high-voltage winding is composed of three winding units H1, H2, and H3 as shown in the figure, and the total number of turns in the winding units H1 and H3 is calculated by the winding unit H.
The number of turns is equal to 2.

These winding units and low voltage windings are arranged on the iron core 1 from the inside in the order of winding unit H3, low voltage winding, and winding unit H2°Hl.

When using a high voltage winding with a low voltage rating, connect the winding units H1 and H3 in series as shown in Figure 5a.
Connect in parallel with 2.

In this way, for example, if you connect the low voltage winding terminals u - v to the power supply and the other high voltage winding terminals U - 0 connect the load,
Load current flows through each winding.

Among these, the current flowing through the high voltage terminal U-0 is the winding unit H1+
The current flows in a shunt to the parallel circuit of H3 and the winding unit H2, but this shunt is controlled by the leakage reactance between the winding unit H1+H3 and the low voltage winding and between the winding unit H2 and the low voltage winding. .

Leakage reactance is proportional to the magnetic energy stored between each of the six windings.

That is, as shown in FIG. 6a, if the amperage distribution between each winding is drawn, the leakage reactance is approximately proportional to the square area thereof.

In Fig. 6a, H2 to L indicated by solid lines are the winding unit H.
The ampere frequency distribution between the winding unit H1+H3 and the low voltage winding ML is shown by the broken line (H1+H3) to L.

Therefore, by adjusting the distance between the windings or the ratio of H□/H3, etc., the square area of the part surrounded by the horizontal axis and the solid or broken line in the figure can be made approximately equal to the winding unit H2. The leakage reactances between the high-voltage winding, the winding unit H1+H3, and the low-voltage winding can be made substantially equal.

In this way, the load current flowing between the high voltage terminals U-0 is divided approximately equally into the winding units H2 and H1+H3.

Therefore, now the low voltage winding capacity is 1. Assuming Op and u, the capacitance of the winding unit H2 and H1+H3 is 0.5p, respectively.
u is required.

On the other hand, when using a high voltage winding with a high voltage rating, three winding units H1, H2 and H3 are connected in series as shown in the diagram in FIG.

If this is done, the number of turns of U-00 between the high voltage terminals will be exactly twice that of FIG.

Considering the load condition as in the previous section, the winding unit H1,
Since H2 and H3 are connected in series, each winding current is equal.

Moreover, the number of turns in the winding unit H1+H3 is selected to be equal to the number of turns in the winding unit H2, so if the capacity of the low voltage winding is 1.0p and u as mentioned above, the capacity of the winding units H1+H3 and H2 is are 0.5p and u, respectively, and Figure 5a
It is no different from the case of .

This shows that the amperage values shared by each winding remain unchanged even in cases a and b in Fig. 5.
In the end, the leakage reactance values (p,
u value) are approximately the same.

This is very favorable in terms of system operation. Furthermore, as can be seen from the winding arrangements in Figure 5 a and b, each winding unit is arranged in a rational manner in terms of insulation, depending on the voltage class it is responsible for. It also has the great advantage of making the whole structure more compact.

In addition, in the above explanation, the position of the low voltage winding is expressed as a winding unit H3.
Although it is limited to between H2 and H2, it is clear that the same effect can be obtained even if it is placed at the innermost side or between the winding units H2 and Ho, as shown in Figures 7 and 8. It is.

In addition, in the above, the dual voltage rating was just doubled or halved, i.e. 275 to V1550 (■) or 77 to V/154 (■). - The present invention can also be applied to cases where the amount is not halved.

For the winding arrangement shown in Figures 9a and b, 275K
This will be explained in detail using the example of V15 o and ■.

In Figures 9a and b, winding units H2 and H1+
H3 is 500-275=225KV, H4 is 275-2
The number of turns corresponds to 25=50KV.

275, as shown in Figure 9a, the winding units H1 + H3 and H2 are connected in parallel, and the winding unit H is connected in parallel.
Connect 4 in series.

In this way, the voltage appearing between the high voltage terminals U-0 will be 27
5 and the voltage corresponding to ■.

As in the case of Fig. 5, if the leakage reactances between the winding unit H1 + H3 and the low voltage winding and between the winding unit H2 and the low voltage winding are made equal, then the winding unit H1 + H
3 and H2 load currents are equally divided.

In this case, the current in the winding unit H4 is equal to the current flowing through the high voltage terminal, that is, twice the current in each of the winding units H1, H2, and H3.

Next, when the rating is 500 to 2, if each high voltage winding unit is connected in series as shown in the diagram in FIG. 9, the voltage appearing between the high voltage terminals U-0 becomes a voltage corresponding to 500 to 2.

In this case, the currents flowing through each high-voltage winding unit are equal, but the currents in Hl, H2, and H3 are -1.1 times higher than when they are rated at 275KVX275, and conversely, the current in H4 is =0. Reduced by 55 times 00.

Therefore, since the ampere load shared by each winding changes in FIGS. 9a and 9b, the leakage reactance (p, u values) varies somewhat.

However, this degree of variation does not pose much of a problem in practice.
If you dislike fluctuations in leakage reactance (p, u values), the distance H1/Hs between each winding unit, including the winding unit H4.
By adjusting the ratio of , etc., it is possible to prevent the .

In addition, although the winding unit H4 is arranged at the innermost position in FIGS. 9a and 9b, the effect of the present invention is not impaired even if it is arranged at another position.

FIG. 10 shows an example of a case where a voltage adjustment tap is attached to the high voltage winding of the transformer according to the present invention explained in FIG.

That is, the main transformer shown in FIG.
A load voltage regulation transformer (hereinafter referred to as LVR
) is placed separately.

In the figure, the currents in the tap windings 31 and 32 are shunted by the leakage reactance between the winding units H1+H3 and H2 of the main transformer and the low voltage winding, so unbalance does not become a problem.

Therefore, when applying to a single-phase transformer, tap winding 31
and 32 to separate phases of a three-phase Y-imaging neutral point switching on-load tap changer (hereinafter referred to as LTC), an LTC with approximately 1/2 the rated current can be used, and When applied to a three-phase transformer, one LTC is installed for the tap winding 31 of each phase, and another LT is installed for the tap winding 32 of each phase.
If you allocate it to 1 C, the cost will be approximately 1/1 as mentioned above.
Since an LTC with a rated current of 2 can be used, this is extremely advantageous especially for large capacity transformers.

Although not shown in the figure, it is also possible to wind the tap windings 31 and 32 in separate LVRs. In this case, when switching to a high voltage rating of the main transformer, one LVR Since it is no longer necessary, it becomes possible to relocate and reuse it as a signal device.

FIG. 11 shows an application example in which the other embodiment of the present invention described in FIG. 9 is further combined with an LVR.

Although it is of course possible to provide a tap directly to the high voltage winding unit H4, the tap winding 31 is provided as a separate winding in the figure.

According to Fig. 11, even if the winding unit H4 is required due to the difference in the dual voltage ratings, it can be wound on the LVR side instead of on the main transformer side. It has the advantage that the winding arrangement on the side can be arranged relatively easily.

As explained above, according to the present invention, a high voltage, large capacity, dual voltage rated transformer can be manufactured simply and rationally in terms of insulation and current distribution, and it is small, economical, and highly reliable. You can get a transformer.

[Brief explanation of drawings]

An example of the configuration of a conventional dual voltage rated transformer shown in Figures 1a and b, where a is a wiring diagram for a low voltage state with parallel connection, b is a wiring diagram for a high voltage status with series connection, and Figure 2a and b
3 is another example of a conventional double voltage rated transformer, a is a connection diagram for a low voltage state with parallel connection, b is a connection diagram for a high voltage state with series connection, and FIGS. 3a and b are FIGS. Figures 4a and 4b show the amperage distribution of each winding corresponding to the state of the wiring diagram shown in Figures 4a and 4b. In the configuration example, a shows a wiring diagram in a low voltage state, b shows a wiring diagram in a high voltage state, FIGS. Figure 6b is a wiring diagram in a high voltage state, Figures 6a and 6b are diagrams showing the ampere frequency distribution of the windings corresponding to the wiring diagram states shown in Figures 5a and b, respectively. 8 and 8 respectively show other embodiments of the dual voltage rated transformer according to the invention, and FIGS. 10 shows another embodiment of the dual voltage rated transformer according to the present invention, in which a is a wiring diagram in a low voltage state, b is a wiring diagram in a high voltage state, and FIG. Voltage state wiring diagram, 1st
FIG. 1 is a wiring diagram showing still another embodiment of the dual voltage rated transformer according to the present invention in a low voltage state. 1.2,3... Iron core leg, 11,12,13゜1
4.15, 16... High voltage winding unit, 21...
...Excitation winding, 31, 32...Tap winding,
Hl, H2゜H3, H4...High voltage winding unit, L
...Low voltage winding unit, U...High voltage line terminal, O...High voltage neutral point terminal, U. ■・・・・・・Low voltage line terminal.

Claims (1)

[Claims] 1. The high-voltage winding is divided into three winding units H1, H2, and H3, and the total number of turns of the winding units H□ and H3 is equal to the number of turns of the winding unit H2. , and these winding units H1, H2, and H3 are wound around an iron core together with a low-voltage winding, and a winding unit group in which the winding units H1 and H3 are connected in series and the winding unit H2 are connected in parallel. a first connection forming a high-voltage winding; and the winding units H1, H2, H3.
A transformer that obtains a dual voltage rating by using one of the second connections connected in series to form a high voltage winding. 2 High voltage winding is divided into four winding units H1, H2, H3゜H4
At the same time, the total number of turns of the winding units H1 and H3 is equal to the number of turns of the winding unit H2, and at least the winding units H1, H2, and H3 are wound around the iron core together with the low voltage winding. A first winding unit in which a winding unit group in which the winding units H1 and H3 are connected in series and a winding unit H2 are connected in parallel, and this is connected in series with a winding unit H4 to form a high voltage winding.
A double voltage rating can be obtained by using either one of the above connections and a second connection in which the above-mentioned winding units H1, H2, H3, and H4 are connected in series to form a high voltage winding. transformer. 3. The transformer according to claim 2, wherein the winding unit H4 is wound on the same core together with the winding units H1, H2, and H3. 4. The transformer according to claim 2, wherein the winding unit H4 is wound around an iron core of an on-load voltage regulator.