JPH0140182Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a transformer with a phase-lag capacity.

For example, in the case of a power distribution line, a leading current flows due to the ground charging capacity of the line. For this reason, conventionally, as shown in FIG. 1, a compensating shunt reactor 3 has been installed on the load 2 side of the power distribution transformer 1. In addition, in the figure, 4 is a power supply, and 5 is an earth charging capacity.

However, in the above-mentioned configuration, it is necessary to install a shunt reactor 3 of considerable capacity in addition to the transformer 1, which not only increases costs but also has the disadvantage of requiring space to install it. . Furthermore, the shunt reactor 3 itself also generates losses, and the delayed current flows through the primary and secondary windings of the transformer 1 and is supplied, so additional losses occur here as well, so this is not an option from an energy saving perspective. It's not a good idea either.

In view of the above-mentioned problems, this invention provides a gap in the iron core of the transformer and adjusts the gap length to increase the no-load excitation current of the transformer and supply a delayed current.

An embodiment of this invention will be explained below based on FIG. The transformer 10 is constructed by winding the secondary winding 16 concentrically.

The gap length of the gap 12 is the same as that of the transformer 10.
The no-load excitation capacity of the transformer 10 is adjusted to be approximately equal to the ground charging capacity of the system line to which the transformer 10 is connected. Note that the normally required capacity is considerably smaller than that of a transformer, so the overall length of the gap 12 provided on the core leg 13 is relatively small.For example, when a 200MVA transformer has an excitation capacity of 50MVA, Approximately 200mm is sufficient.

According to the above configuration, as shown in the equivalent circuit diagram shown in FIG. 3, an exciting inductance Ls corresponding to the gap 12 of the core leg 13 is generated. L ₁ and L ₂
is the primary leakage reactance of the transformer 10, and these leakage reactances L ₁ and L ₂ are much smaller than the excitation inductance Ls, so the equivalent circuit diagram shown in Figure 3 shows a shunt to the secondary (load) side. This is approximately the same as when the reactor 3 (see FIG. 1) is connected. That is, if the inductance of the shunt reactor 3 is Ls', and the number of turns of the primary winding and secondary winding of the transformer 1 are n ₁ and n ₂ , respectively, then Ls' = (n ₂ / n ₁ ) ² Ls This provides a compensation effect for the earth charging capacity 5 on the load 2 side. In addition, r ₁ and r ₂ in the figure are primary and secondary
The secondary resistances, iLs and iLs' are the excitation currents on the primary and secondary sides.

As detailed above, according to this invention, the primary and secondary windings are wound concentrically around the core leg, so the gap length of the core can be easily adjusted, and the transformer itself is connected to the system line. Since it can be equipped with a slow phase capacity that corresponds to the earth charging capacity, it is possible to compensate for the earth charging capacity of the system line without separately installing a shunt reactor as in the past, and it is also possible to install a shunt reactor. This has the effect of reducing associated costs, installation space, etc.

Furthermore, the loss occurring in the shunt reactor is eliminated, and the excitation current iLs for the gap only flows to the primary winding of the transformer as shown in Figure 3, so the loss occurring in the transformer due to this is also reduced. Since only the primary winding is required, the loss of the transformer itself is reduced compared to the conventional case where a shunt reactor is placed separately on the load side, resulting in an energy saving effect.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing a conventional example, Fig. 2 is a schematic sectional view showing an embodiment of this invention, Fig. 3 is an equivalent circuit diagram of this invention, and Fig. 4 is an equivalent circuit diagram of Fig. 1. It is. 10: Transformer, 11: Iron core, 12: Gap,
13: Iron core leg, 14: Yoke, 15: Primary winding,
16: Secondary winding.

Claims (1)

[Scope of utility model registration request] A gap is provided in the core leg of the transformer connected to the system line, and the primary and secondary windings are wound concentrically around this core leg, and the no-load excitation capacity of the transformer is A transformer in which the gap length of the gap is adjusted to be approximately equal to the earth charging capacity of the connected system line.