JPH0215238Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a disconnector for power transmission lines, and in particular to a disconnector suitable for significantly reducing surge voltage even when a transformer is installed on the input line. be.

When starting or stopping power transmission via a power transmission line, the line is opened and closed using a break switch. At this time, the opening/closing operation may generate an abnormally high switching surge voltage between the power cable, particularly the power cable, the sheath, and the ground, which may destroy the sheath anticorrosion layer. Therefore, in order to suppress this abnormal voltage, a closing resistor or a disconnector as shown in FIG. 1 has been proposed and has already been put into practical use.

In FIG. 1, 1 is an overhead power transmission line, 2 is a breaker connected to the overhead power transmission line, the breaker 2 connects an auxiliary breaker 4 in parallel with a closing resistor 3,
The configuration is such that the main shingle disconnection section 5 is connected in series to the parallel circuit of the closing resistor 3 and the auxiliary shingle disconnection section 4. 6 is an underground power transmission line, and 7 is a transformer.

A normal closing operation is performed with the closing resistor 3 connected to the line 1, and after the transient voltage has sufficiently decreased, the closing resistor 3 is short-circuited by assisting the closing section 4. Return to normal operation. Therefore, the switching surge voltage occurs when the resistor is closed and when the resistor is shorted, and the resistance value of the closing resistor (generally 400 to 1000 Ω) is adjusted so that the two values are balanced.
has been established.

By the way, this closing resistor and disconnector are effective when no transformer is installed on the line side where the closing resistor 3 is installed. It can be suppressed to 2 to 1/4. However, if the transformer 7 is installed on the line on the input side as shown in Figure 1, the surge voltage may become abnormally high when the input resistor 3 is short-circuited due to the rush current of the transformer 7. be.
In other words, in large capacity transformers, the transformer's closing excitation impedance (approximately 100Ω) is often smaller than the resistance value of the closing resistor 3, and for several cycles after turning on, the closing resistor 3 supplies most of the power transmission voltage. Therefore, when the closing resistor 3 is short-circuited 10 to 20 mS after closing, there is a possibility that a surge voltage similar to that without the closing resistor 3 may be generated.

In order to improve this, it is possible to make the resistance value of the closing resistor 3 sufficiently smaller than the closing excitation impedance of the transformer 7, but in this case, even if the surge voltage when the resistor is shorted can be reduced, On the contrary, the surge voltage will increase, and this is not a very effective countermeasure overall. It is also possible to use a reactor instead of the closing resistor 3, but in this case, the surge voltage will be suppressed on the line on the side where the line is turned on, but a high surge voltage will occur on the line on the opposite side. , which is also not very effective overall.

The present invention was developed in view of the above, and its purpose is to provide a power transmission line disconnector that can significantly suppress switching surge voltages that occur even if a transformer is installed on the power transmission line. It is about providing the equipment.

That is, the shield disconnector for power transmission lines of the present invention has an auxiliary shield disconnector in parallel with a switching surge suppressor having a configuration in which a reactor is installed around the outer periphery of a closing resistor and these are connected in parallel. The present invention is characterized in that a main shield section is provided in series with the parallel circuit of the switching surge suppressor and the auxiliary shield section.

The present invention will be explained in detail below using the embodiments shown in FIGS. 2 to 4.

FIG. 2 is a circuit diagram showing an embodiment of the breaker according to the present invention. In FIG. 2, 8 is a switching surge suppressor, which is composed of a parallel circuit of a closing resistor 3 and a reactor 9, and an auxiliary shield section 4 is provided in parallel with the switching surge suppressor 8. . and,
A main shield section 5 is provided in series with the parallel circuit of the switching surge suppressor 8 and the auxiliary shield section 4.

Note that the closing resistor 3 of the switching surge suppressor 8 is
Since it is necessary to suppress switching surge voltage, the resistance value is selected to be several times the surge impedance of the part where the circuit breaker is installed (generally 400 to 1000Ω). In addition, the inductance L of the reactor 9 has a larger impedance ωL than the closing resistor 3 while the high-frequency surge voltage is attenuated, and the closing excitation inductance of the transformer 7 (see Fig. 1) connected to the power transmission line. It has been selected to be smaller. The high frequency component of surge voltage is generally 1
Values of ~20MHz have been observed, so 1MHz
To make the resistance value the same as the resistance value of closing resistor 3 (for example, 1000Ω), L=1000/2π×10 ⁶ = 159×10 ^-6
(H).

On the other hand, the input excitation inductance of transformer 7 is several
Since it is on the order of 100mH, the inductance L of reactor 9 should be 200μH to 10
It may be selected to be about mH.

FIG. 3 is a concrete structural diagram showing one embodiment of the opening/closing surge suppressor 8 of FIG. 2. A reactor 9 is installed around the outer periphery of the closing resistor 3, and the whole is connected to the insulator tube 1.
0, and sulfur hexafluoride (SF ₆ ) or insulating oil is sealed inside the insulator tube 10.

In general, switching surge voltage is composed of a high-voltage (several times the transmission voltage) high-frequency (several megs to tens of megahertz) wave that attenuates in a few microseconds and a low-voltage, low-frequency wave that lasts several tens of milliseconds. However, the switching surge suppressor 8 acts as a resistance element against high frequency waves and as a reactor against low frequency waves.

Next, let us consider the surge voltage when a closing operation is performed using the breaker according to the present invention.
The power-on operation is performed by closing the main shield section 5 while leaving the auxiliary shield section 4 open. At this time, since the switching surge suppressor 8 is inserted in series with the power transmission line, High-frequency surge voltages are suppressed by resistors, and surge voltages generated on power transmission lines are significantly reduced. After approximately 10 to 20 mS has elapsed after this closing operation, the auxiliary shingle breaker 4 is closed and the switching surge suppressor 8 is short-circuited, completing all the shunt breaker operations. Since the voltage is at a low frequency, the impedance of the switching surge suppressor 8 is sufficiently small, and even considering the effect of the rush current of the transformer 7, the voltage applied to this part is small, and this operation The generated surge voltage will be minute. Therefore, the surge voltage generated by both operations (turning on and shorting) becomes smaller as a whole.

As mentioned above, according to the embodiment of the present invention, (1) Even if a transformer is installed on the input line, the switching surge voltage can be significantly reduced compared to that of the conventional disconnector, and the transmission line configuration The element can be protected from switching surge voltage.

(2) The closing resistor 3 is designed taking into consideration the surge heat caused by the surge current flowing through it, but in the case of the disconnector according to the present invention, the surge current only flows through the closing resistor 3 for a short period of time. Therefore, the closing resistor 3 can be made small.

There is an advantage.

FIG. 4 is a circuit diagram showing another embodiment of the present invention,
The same parts as in FIG. 2 are designated by the same reference numerals. Fourth
In the figure, a switching surge suppressor 8' is used which has a structure in which a low resistor 11 is further connected in series to a parallel circuit of a closing resistor 3 and a reactor 9.

Note that the resistance value of the low resistor 11 is set to be approximately the same as the inrush excitation impedance of the transformer 7 (see FIG. 1) installed on the input side. According to FIG. 4, the switching surge voltage is suppressed by the parallel circuit of the closing resistor 3 (the resistance value is several times the surge impedance of the line) and the reactor 9, and the rush current of the transformer 7 is suppressed by the low resistor 11. It has the effect of being

As explained above, according to the present invention, even if a transformer is installed on the power transmission line, the switching surge voltage that occurs can be significantly suppressed, and the components of the power transmission line can be protected from the switching surge voltage. There is an effect.

Further, according to the present invention, the opening/closing surge suppressor
Since it has a configuration in which a reactor is installed around the outer circumference of the resistor and these are connected in parallel,
Switching surges can be suppressed by resistors and reactors with constant components in current and frequency, and this has the effect of effectively suppressing all switching surges at disconnected sections that open and close due to various factors.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a conventional closing resistor and disconnector installed on a power transmission line, Fig. 2 is a circuit diagram showing an embodiment of the present invention's cutter and disconnector for power transmission lines, and Fig. 3 2 is a specific structural diagram showing one embodiment of the switching surge suppressor shown in FIG. 2, and FIG. 4 is a circuit diagram showing another embodiment of the present invention. 1: Overhead transmission line, 3: Closing resistor, 4: Auxiliary shield section, 5: Main shield section, 7: Transformer, 8,
8': Opening/closing surge suppressor, 9: Reactor, 1
0: Insulator, 11: Low resistance resistor.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In a shield circuit breaker used in a power transmission line, a surge suppressor is connected in parallel with a switching surge suppressor having a configuration in which a reactor is installed around the outer periphery of a closing resistor and the resistors are connected in parallel. A shield disconnector for a power transmission line, characterized in that a main shield disconnector is provided in series with a parallel circuit of the switching surge suppressor and the auxiliary shield disconnector. 2. The switching surge suppressor has a structure in which a reactor is installed around the outer periphery of a closing resistor, these are connected in parallel, and the reactor is housed in an insulator tube, and sulfur hexafluoride gas or insulating oil is sealed in the insulator tube. A power transmission line breaker as set forth in claim 1 of a certain utility model registration claim. 3. The sheath breaker for a power transmission line according to claim 1, wherein the switching surge suppressor has a low resistor connected in series with a parallel circuit of a closing resistor and a reactor.