JPH0464205A - Tap changer - Google Patents

Abstract

PURPOSE:To miniaturize a tap changer, and to reduce the quantity of heat dissipation by bringing one tap to an OFF state when load currents reach a zero point by utilizing the OFF state of a thyristor and bringing other taps to an ON state. CONSTITUTION:The 'ON' and 'OFF' states of first and second TRIACs 11, 13 are changed in response to the state of the changeover of a TRIAC changeover switch 23 in a tap changer 1, thus tap-changing the A-tap 9a and B-tap 9b of a transformer 7. The taps are changed without flowing circulating currents between the A-tap 9a and the B-tap 9b. The changeover of the A-tap 9a and the B-tap 9b is completed approximately instantaneously when load currents reach 'a zero point'. Accordingly, a current-limiting resistor and a current limiting reactor for inhibiting circulating currents need not be used, thus attaining miniaturization, then reducing the quantity of heat dissipation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tap changer for changing the taps of a transformer.

[Prior art] Conventional tap changer Table 1 A tap changer is used to control the main motor voltage by sequentially switching the taps of a transformer to control the speed of an AC electric vehicle, or to adjust the voltage value of power transmission and distribution. There is.

A tap changer is equipped with a contact changeover switch and a current-limiting resistor or current-limiting reactor.The changeover switch is
This is used to switch the taps of a tap transformer. Current limiting resistors and current limiting reactors are used to prevent arcing and large circulating currents from flowing between taps when a changeover switch is switched.

[Problem to be solved by the invention] However, conventional tap changers (like conventional tap changers) require a large number of large-sized devices such as contact type changeover switches, current-limiting resistors, and current-limiting reactors, and require a large storage space. In addition, it was necessary to consider heat radiation from the current limiting resistor and the current limiting reactor.Therefore, there was a problem that a larger housing space was required than in the conventional 1, and the number of parts increased.

An object of the present invention is to solve the above-mentioned problems and provide a tap changer that requires a small housing space and generates less heat.

[Means for Solving the Problems] As a means for achieving the above object, the tap changer of the present invention has two tap changers provided on the load side or the power supply side of the transformer.
In the tap changer for switching from one tap to another tap, a first thyristor is provided to turn on or off between the one tap and the load or the power supply, and the other tap and a second thyristor that turns on or off between the load or the power supply, a switching instruction means for instructing switching from the one tap to the other tap, and the switching instruction means When switching is instructed, the supply of a turn-on signal to the first thyristor is stopped, and the turn-on signal is supplied to the second thyristor after the current flowing through the first thyristor reaches a zero point. The gist of the present invention is to include a turn-on signal switching means.

[Operation] The tap changer of the present invention (when switching from one tap to another tap is instructed by the front switching instruction means, the turn-on signal switching means first stops supplying the turn-on signal to the first thyristor. .In this state, when the current flowing through the first thyristor reaches the zero point, the first
thyristor is turned off, and current no longer flows through the first thyristor.

Next, after the current flowing through the first thyristor reaches a zero point, a turn-on signal is supplied to the second thyristor by the turn-on signal switching means.

As a result, the second thyristor is turned on, and current flows through the thyristor of the tube 2 from now on. That is, when switching of the taps is instructed by the switching instruction means, when the current flowing through one tap reaches the zero point, current no longer flows through this one tap, and then current starts flowing through the other taps.

That is, the taps are switched from one tap to another.

[Example] Next, one embodiment of the tap changer of the present invention will be described.

FIG. 1 is an overall configuration diagram of a tap changer 1 of this embodiment. Tap changer 1 (connected to transformer 7).

The transformer 7 (its primary winding 5 is connected to the companion AC power supply 3 and its secondary winding 9 is connected to the tap changer 1).

The secondary winding 9 [includes an LA tap 9a and a B tap 9b. The tap changer 1 includes a first triax 11;
[second triax] 3, a CT, and a control circuit 15.

The first triax 11 (interposed between the LA tap 9a and the CT)
It is interposed between b and CT.

A first triac control signal line 11b and a second triac control signal line 13b from a control circuit 15 are connected to the gate 1-11a of the first triac 11 and the gate 13a of the second triac 13.

CT is the first. Second triac 11, 13 and load 2
It is interposed between 1 and 1. A signal line CTa that outputs the current transformation value of CT is connected to the control circuit 15. As a result, CT is the first. The current value of the current flowing into the load 21 through the second triacs 11 and 13 is output to the control circuit 15.

A triac changeover switch 23 is connected to the control circuit 15.
Either the = second signal or the second = first signal is output to the control circuit 15 .

The control circuit 15 (component) has a logic circuit configuration (not shown), and the circuit is configured to operate as shown in FIG. 2 as an example.

Control circuit] 5 (Above As shown in FIG. 2, it operates based on the load current flowing through the CT and the position of the triac changeover switch 23. For example, if the TRIAC changeover switch 23 When the signal is output to the control circuit (the first triac control signal is turned on, that is, the signal that turns the first triac 11 on is outputted. In this state, the triac changeover switch 23 When the position is switched to output the 2nd signal, the 1st tryack control signal is changed from "on" to "off" as shown by ■ in Figure 2. - The 1st tryack control signal is turned "off". In this state,
When the load current reaches the "zero point", the second triac control signal is changed from "off" to "on" as shown by ■ in Figure 2.
Change to This causes the second triax 13 to become "on".

Also, when the triac selector switch 23 is switched from "1st = 2nd" to outputting the "2nd = 1st" signal, contrary to the above, first the 2nd triac is output]
3 goes into the "off" state, then the first tryack 1]
is in the "r-on" state.

As explained above, the tap changer] (corresponding to the switching state of the triac changeover switch 23)
The "on" and "off" states of the triacs 11 and 13 are not changed, and thereby the tap switching between the A tap 9a and the B tap 9b of the transformer 7 is performed. Moreover, this tap switching is performed without any circulating current flowing between the A tap 9a and the B tap 9b. Also, A tap 9a and B
Switching with tap 9b is completed almost instantaneously when the load current reaches the "zero" point.

As a result, there is no need to use a current-limiting resistor or current-limiting reactor to suppress circulating current in the tap changer of this embodiment, making it possible to achieve miniaturization and reduce the amount of heat dissipation. This has an excellent effect.Furthermore, by completing switching instantaneously, the responsiveness of voltage control can be improved.In other words, voltage control accuracy can be improved.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various embodiments can be implemented without departing from the gist of the present invention, for example, as shown below.

In the embodiment shown in FIG. 1, an example was shown in which two triacs are switched, but instead of this, as shown in FIG. 47 and may be configured to be sequentially switched by the control circuit 50.Also, in this case,
An AVR is provided, and a voltage value sensor 53 detects the terminal voltage of the load 5.
The control circuit 50 may be configured to inspect the product and send tap up and tap down signals from the AVR so that the voltage value becomes a predetermined value.

1 and 3 show a configuration in which triacs are arranged according to the Yotrans taps to switch taps, but instead of this, as shown in FIG. 4, a mechanical switch S] ~S6 and two triacs 61 and 62 may be used together.In this case, one of the transformers 70
To switch the tap 71 to the other tap 72, for example, as shown below, the switches S1 to S6 and the triac 6
1.62. Initially (the triac 61 and the switch S1 are turned on). First, the switch S2 is turned on, and the triac 61 is turned on.
OFF” state. When the load current reaches the "zero" point, the triac 62 is placed in the "on" state and the switch 51 is turned on.
is in the "off" state. As a result, one tap 71 is switched to another tap 72. Therefore, in Fig. 4, a switch with mechanical contacts is used, but
This switch 81-361 friend circuit "on J"off"
The switches 81 to S6 only change the state, and do not have a current cutoff function. In other words, the tap changer shown in FIG. 4 achieves both the size reduction and the reduction in heat dissipation.

Further, although the above embodiment uses a triac, any PnPn element such as a reverse blocking thyristor or a bidirectional thyristor may be used instead.

In the above embodiment, the tap of a single-phase transformer is switched, but instead of this, a configuration may be adopted in which the tap of a polyphase-connected transformer such as a three-phase transformer is switched.

[Effects of the Invention] The tap changer of the present invention utilizes the off state of the thyristor to turn one tap off and then turn on the other taps when the load current reaches the zero point. The tap of the transformer is changed by As a result, both taps before and after switching can be performed instantly.
Since tap switching is performed without entering the "on" state, tap switching can be performed without passing a through current between the taps. As a result, an extremely excellent effect is achieved in that miniaturization is not achieved and the amount of heat dissipated is reduced.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a tap changer according to an embodiment of the present invention;
The figure is an explanatory diagram of its operating state, and FIGS. 3 and 4 are configuration diagrams of modified examples. 1... Tap changer 7. 30. 70...Transformer 1] ---First triac 13...Second triac 15.50...Control circuit 31-37,71.72...Taps 41-47...Triac 21.51.・・Load CT (current transformer)

Claims (1)

[Claims] In a switch that switches from one tap to another tap in two or more tap holes provided on the load side or the power source side of a transformer, the connection between the one tap and the load or the power source is provided. a first thyristor that turns on or off; a second thyristor that turns on or off between the other tap and the load or the power supply; switching instruction means for instructing switching to the tap; and when switching is instructed by the switching instruction means, supplying a turn-on signal to the first thyristor is stopped, and the current flowing through the first thyristor is stopped; and turn-on signal switching means for supplying a turn-on signal to the second thyristor after reaching the zero point.