JPH0224100B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to shunt reactors.

As is well known, shunt reactors are installed at substations at the receiving or transmitting end of a power transmission system, and are widely used as a means of supplying delayed phase reactive power to the grid in order to suppress voltage increases during light loads. There is. For example, in a long-distance high-voltage power transmission system, when a line accident occurs and the faulty line is severed, the capacitance of the severed line and its line are reduced due to induction from the healthy line. It is known that series resonance occurs due to the inductance of the shunt reactor connected to the inductance, and abnormal voltage is generated. Therefore, conventional measures have been taken to suppress this abnormal voltage.

Figures 1 and 2 are circuit diagrams showing an example of conventional countermeasures. A circuit 6 in which a resistor 4 and a switch 5 are connected in parallel is inserted. Note that 7 is a terminal on the neutral point side, which is grounded directly or via an arrester 8 as shown in the figure. In FIG. 2, the first stage circuit 6 is connected to the neutral point side.

In either case of Fig. 1 or Fig. 2, the switch 5
is always closed, so that the resistor 4 is always in a short-circuited state. If a track accident occurs while the shunt reactor is in operation, the line break or disconnector will be opened, and at the same time the switch 5 will be opened.
is inserted in series with the shunt reactor, so abnormal voltage due to resonance is suppressed by this resistance. After the track accident is restored, the switch 5 is closed and the resistor 4 is short-circuited.

However, according to such a configuration, in a high voltage or ultra-high voltage system, the resistor 4 and switch 5 used here are
Both require the use of high-voltage or ultra-high-voltage products, and therefore have the disadvantage of being expensive or bulky due to their high-voltage or ultra-high-voltage design, which is actually a major obstacle to their practical application. It is becoming.

An object of the present invention is to simplify a resistor for suppressing abnormal voltage at the time of a line fault.

This invention uses a magnetic flux commutation type variable capacitance shunt reactor as a shunt reactor, and its control winding is provided with a resistor that is connected in the event of a breakage due to a line accident or abnormal voltage generation due to this. It is characterized by

FIG. 3 shows an embodiment of the present invention, in which 11 is a main winding (one phase is shown) of a magnetic flux commutation type variable capacitance shunt reactor 10, one terminal 12 of which is connected to a line. Also, the terminal 13 on the neutral point side is grounded directly or via an arrester 14. 15 is a control winding, and 16 is a switch for the control winding. Usually, the shunt reactor 10 has a main winding 11 connected to a main core whose both ends are magnetically short-circuited by a yoke core.
Further, the control winding 15 is wound inside the control winding 15, and a switch 16 is connected to both ends of the control winding 15.

When the switch 16 is open, all of the generated magnetic flux flows back through the main core and the yoke core. Therefore, almost no delayed excitation current flows, and the reactor capacity becomes substantially zero. Also, when the switch 16 is closed and the control winding 15 is short-circuited,
Since the magnetic flux interlinking with the control winding becomes zero, the magnetic flux that had previously passed through the main core inside the control winding moves to the space between the main winding and the control winding (commutation).
Therefore, the magnetic resistance of the magnetic path increases, and to compensate for this, a delayed magnetizing current flows in the main winding, so
Slow phase reactive power will be supplied to the line.

According to this invention, in the embodiment shown in FIG. 3, a resistor 17 for suppressing abnormal voltage is connected in series with a switch 18, and this series circuit is connected in parallel with a control winding 15. The switch 18 is normally open, but if an abnormal accident occurs on the line and the line break is suddenly cut off, the switch 18 is immediately closed. Also, if the switch 16 was closed at this time, it is opened. When the accident is restored, the switch 16 is closed, and then the switch 18 is opened.

In the above configuration, when the line is briefly cut off due to the occurrence of a track accident, the switch 18 is closed, and when the switch 16 is opened, the resistor 17
will be connected to the control winding 15. Therefore, since a resistor is equivalently inserted into the main winding 11, the abnormal current due to resonance accompanying the occurrence of a line fault is quickly attenuated, and the abnormal voltage is suppressed. In this case, in the magnetic flux commutation type variable capacitance shunt reactor equipped with the control winding 15 described above, the voltage of the control winding 15 can be selected relatively freely, so the resistor 17 and switch 18 connected here are low. It can be used for voltage, so the design is easy and compact, and the manufacturing cost is low.

The embodiment shown in FIG. 4 shows a configuration in which a discharge gap 28 is used in place of the switch 18 shown in FIG. The discharge voltage of the discharge gap 28 is preset to a value higher than the constant induced voltage when the control winding 15 is open. In addition, if the switch 16 is closed at the time of a track accident and breakage, it shall be opened promptly when the breakage occurs. In this configuration,
Since a voltage corresponding to the abnormal voltage generated by the resonance is induced between the terminals of the control winding 15, the discharge gap 28 is discharged by this induced voltage and becomes conductive. As a result, as in the case of FIG. 3, a resistor is equivalently connected in series with the main winding 11, thereby suppressing abnormal voltage.

The embodiment shown in FIG. 5 shows a configuration in which a nonlinear resistor 38 made of, for example, zinc oxide is used in place of the switch 18 shown in FIG. This nonlinear resistance 3
The discharge starting voltage of No. 8 is set to a value higher than the constant induced voltage when the control winding 15 is open. Further, the switch 16 is assumed to be opened promptly in the event of a track accident or disconnection. Even in this configuration, a voltage corresponding to the abnormal voltage generated by resonance is induced between the terminals of the control winding 15, so the nonlinear resistor 38 becomes conductive due to this induced voltage, and the third
Abnormal voltage is suppressed in the same way as in the case of FIGS.

As detailed above, according to the present invention, a resistor for lower voltage can be used as a resistor for suppressing abnormal voltage due to line breakage in the event of a railway accident, and therefore The design thereof can be simplified, and it can be made smaller and the cost can be reduced.

[Brief explanation of drawings]

1 and 2 are circuit diagrams of a conventional example, and FIGS. 3 to 5 are circuit diagrams showing each embodiment of the present invention. 10...Shunt reactor, 11...Main winding, 1
5... Control winding, 16... Switch, 17... Resistor, 18... Switch, 28... Discharge gap, 3
8...Nonlinear resistance.

Claims (1)

[Claims] 1. A magnetic flux commutation type variable capacitor equipped with a main winding branched from and connected to the line, and a control winding that is normally open at both ends and is short-circuited when supplying slow phase reactive power to the line. In the shunt reactor of
A shunt reactor in which a resistor for suppressing abnormal voltage is connected across the control winding whose both ends are open when a line accident occurs or abnormal voltage is generated.