JP2642825B2 - Single phase load tap change transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-phase load tap change transformer.

[0002]

2. Description of the Related Art In a large-capacity power transmission transformer having a tertiary winding, in order to suppress a short-circuit current of a tertiary circuit to be equal to or less than a breakable current of a generally used circuit breaker,
It is necessary to increase the impedance between primary and tertiary and between secondary and tertiary to a certain value or more. In order to fulfill the demand, if a current limiting reactor is installed in the tertiary circuit or a single-phase device is used, for example, Japanese Patent Application Laid-Open No.
As shown in Japanese Patent No. 75210, a structure in which a primary high-voltage winding is divided into two in series and a secondary medium-voltage winding is divided into two in parallel is used, and a tertiary low-voltage winding is formed of two iron core legs. It is configured to be arranged on only one side. In this way, the entire current of the tertiary circuit flows through one leg, and the tertiary low-voltage winding is divided by one in comparison with the primary and secondary windings.
The impedance between the second and third orders and between the second and third orders can be greatly increased.

[0003]

In a power transmission transformer, power passes through the power transformer in order to maintain a transmission voltage (which may be primary or secondary) at an appropriate value. In order to correct the voltage fluctuation in such a case, a load for normal phase adjustment (a capacitor or a shunt reactor) is connected to the tertiary winding. Conventionally, the phase adjustment load is not often larger than 1/3 of the primary or secondary capacity of the transformer, and the tertiary winding capacity is 1/3 of the primary and secondary winding capacity.
This was not required. However, in recent years, the amount of power transmission has increased significantly, and in some cases, the capacity of the tertiary winding may need to be 1/3 or more of the primary and secondary windings. I have. In such a case, the size of the tertiary winding is larger than before, and the size of the secondary intermediate voltage winding is also larger for the reasons described later. There is a possibility that the primary and secondary capacities (that is, equivalent to the power transmission capacity) of the device are restricted.

[0004] When the tertiary capacity is increased as described above, special measures are required to make the primary and secondary capacities the same as the conventional capacity due to transportation restrictions.

The present invention has been made in view of the above points, and makes it possible to minimize the decrease in the primary and secondary capacity (power transmission capacity) as much as possible even when the capacity of the tertiary low-voltage winding is increased. It is an object of the present invention to provide a single-phase load tap change transformer.

[0006]

An object of the present invention is to provide a primary high-voltage winding divided into two and connected in series so that the maximum value of the current flowing through each of the divided secondary intermediate-voltage windings is substantially equal. Is achieved by adjusting the ratio of the number of turns.

[0007]

Since the above means is provided, the winding widths of the two secondary medium voltage windings can be made substantially equal.

[0008]

Next, the present invention will be described in detail with reference to examples.

[Embodiment 1] FIG. 1 shows an embodiment of the present invention. Divided core legs C ₁ two or more legs, C ₂ to the primary high voltage winding H ₁ having a tap winding T _W1, T _W2, H ₂ and secondary in voltage winding M _1, M ₂ into two, respectively Are arranged on different iron legs C ₁ and C ₂ , and the two divided primary high-voltage windings H ₁ and H ₂ are connected in series, and the two divided secondary medium-voltage windings M ₁ and M ₂ are connected. Of the high-voltage windings H ₁ and H ₂ , which are connected in parallel and divided into two tertiary low-voltage windings T each composed of one winding unit, the iron core leg C on which the line-side high-voltage winding H ₁ is disposed. _{In the} single-phase load tap-changing transformer arranged at ₁ in the present embodiment, two taps are used so that the maximum value of the current flowing through each of the divided secondary intermediate voltage windings M ₁ and M ₂ is substantially equal. And the winding number ratio of the primary high-voltage windings H ₁ and H ₂ connected in series was adjusted. By doing so, the winding widths of the two secondary medium-voltage windings M ₁ and M ₂ can be made substantially equal, and the entire transformer can be downsized. Even when the capacity of the tertiary low-voltage winding T becomes large, it is possible to obtain a single-phase-load tap-changing transformer capable of minimizing a decrease in primary and secondary capacity (power transmission capacity).

[0010] That is explained in the following based on FIG. 1 has two core legs C ₁ and C _2, Tesshin'ashi C ₁ 1 order high-voltage winding to side H _1, during the secondary voltage winding M _1, 3 A secondary low-voltage winding T is disposed, and a primary high-voltage winding H ₂ and a secondary medium-voltage winding M ₂ are provided on the iron core leg C ₂ side.
And tap windings T _W1 and T _W2 . The primary high voltage windings H ₁ and H ₂ are connected in series, and the secondary medium voltage windings M ₁ and M ₂ are connected in parallel. Without this particular to adjust the configured ratio of the high-voltage line H ₁ and the number of turns of H ₂ in the transformer to 1: 1 (the same primary high capacity voltage winding H _1, H ₂ And the current flowing through the secondary medium-voltage windings M ₁ and M ₂ becomes equal when no current flows through the tertiary low-voltage winding T (disposed only on the iron leg C ₁ ). When current also flows to the low voltage winding T, a current flows to compensate the ampere-turn of the same core leg C ₁ to are arranged secondary low voltage winding M ₁ in the third-order low-voltage winding T. Thereby, the iron core leg C
Current flowing in the secondary are arranged in _one to-voltage winding M ₁ I
_M1 is larger than the current I _M2 flowing in the secondary is arranged Tesshin'ashi C ₂ to voltage winding M _2, the number of turns N _H1 of the primary high voltage winding H ₁ in the present embodiment and H _2, N The ratio of _H2 is adjusted as described below.

[0011] The ratio between Tesshin'ashi winding number of C ₁ to disposed in that primary high voltage winding H ₁ N _H1 and the number of turns of the core leg C ₂ are disposed in the primary high voltage winding H ₂ N _H2 By adjusting,
The maximum values of the currents I _M1 and I _M2 flowing through the secondary intermediate voltage windings M ₁ and M ₂ are made substantially equal. Thereby, the secondary medium voltage windings M ₁ and M ₂
Are made substantially equal in width, thereby making it possible to downsize the entire transformer. The ratio of the number of turns N _H1 to N _H2 should be determined depending on the capacity of the tertiary low-voltage winding T.

As an example, a case where the primary capacitance and the secondary capacitance are equal and the tertiary capacitance is 1/2 of the primary / secondary capacitance will be described. Usually, the transformer for power transmission is a tap change method at load, so that the tap is connected to the primary high voltage winding H _2.
, The tap range is ± 7.5%, and the number of taps is 27. Primary high voltage winding H ₁ ,
The ratio of the number of turns N _H1 to N _H2 of H ₂ was set to about 44:56. 2
The current flowing through the two secondary medium voltage windings M ₁ and M ₂ varies depending on the tap position.

FIG. 3 is a diagram showing the relationship between the tap positions and the currents I _M1 and I _M2 flowing through the secondary intermediate voltage windings M ₁ and M ₂ when the primary, secondary and tertiary rated capacities are respectively taken. As shown in FIG. 2, the current I _M1 flowing through the secondary intermediate voltage winding M ₁
Is lowest at tap 1 (highest voltage) and tap 2
It becomes maximum at 7 (lowest voltage). Secondary medium voltage winding M ₂
The current I _M2 flowing through the circuit has the opposite tendency.

The number of _turns N _H1 , N _{H2 of the} primary high voltage windings H ₁ , H ₂
Medium-voltage winding M when the ratio is set to 1: 1 without particular adjustment
_1, M ₂ in the current flowing _I'M1, showing a _I'M2 by a one-dot chain line.
Maximum current _I'M1 of current _I'M1 flowing within Tesshin'ashi C ₁ side voltage winding M ₁ (max) is the maximum value of the current _I'M2 flowing to the voltage winding M ₂ in the Tesshin'ashi C ₂ side It is 20% larger than the current I ' _M2 (max). On the other hand, if the ratio of the number of turns N _H1 , N _H2 of the primary high-voltage windings H ₁ , H ₂ is 44:56, the current I _M1 ,
I _M2 becomes characteristic shown by the solid line in FIG. 2, the current flowing through the voltage winding M ₂ in the current I _M1 (max) and the core leg C ₂ side flowing through the voltage winding M ₁ in the Tesshin'ashi C ₁ side I _M2 ( max) can be made substantially equal.

As described above, according to this embodiment, the winding widths of the two secondary intermediate voltage windings can be made substantially equal, and the transformer can be downsized as a whole.

[0016]

As described above, the present invention relates to a primary high-voltage winding divided into two and connected in series so that the maximum current flowing through each of the divided secondary intermediate-voltage windings is substantially equal. , The winding widths of the two secondary medium-voltage windings can be made substantially equal, and the entire transformer can be downsized. It is possible to obtain a single-phase-load tap-changing transformer capable of minimizing the decrease in the primary and secondary capacities (power transmission capacities) even if the capacity of the line is increased.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a single-phase load tap switching transformer of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a current flowing through a secondary intermediate voltage winding and a tap position.

[Explanation of symbols]

C ₁ , C ₂ … iron leg, H ₁ , H ₂ … primary high voltage winding, M ₁ , M ₂
... Secondary medium voltage winding, T ... Tertiary low voltage winding, _TW1 , _TW2 ... Tap winding.

Claims (2)

(57) [Claims] An iron core having tap windings on two or more iron core legs.
The secondary high-voltage winding and the secondary medium-voltage winding are each divided into two and arranged on different iron legs, and the two divided primary high-voltage windings are connected in series, and the two divided secondary high-voltage windings are connected. The medium-voltage windings are connected in parallel, and the tertiary low-voltage winding composed of one winding unit is arranged on the leg on which the line-side high-voltage winding is arranged among the two divided high-voltage windings. In a single-phase load tap switching transformer, the primary high voltage winding divided into two and connected in series such that the maximum value of the current flowing through each of the two divided intermediate voltage windings is substantially equal. A single-phase load tap switching transformer characterized by adjusting a winding ratio. 2. The winding number ratio of the primary high-voltage winding is adjusted by the capacity of the tertiary low-voltage winding.
A single-phase load tap change transformer as described.