JPS638687B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to substation equipment using a gas insulated switchgear having a reactor on the transmission line connection side of a bus bar.

When mutual connections between switchgear are made using gas-insulated conduits or coaxial cables, overvoltage is generated due to the reciprocating propagation of traveling waves caused by restriking when the disconnector is opened and closed, and this can cause damage to the switchgear, transformer, and reactor. It may destroy the insulation of substation equipment. One method for preventing this dielectric breakdown is to provide a parallel resistor in the disconnector and try to suppress the occurrence of overvoltage by re-igniting the circuit via this resistor.

Although using a disconnector with a resistor has the effect of reducing overvoltage, attaching a resistor to the disconnector increases the radial or axial dimension of the disconnector. Furthermore, the internal structure becomes complicated, resulting in increased weight and price. Since a large number of disconnectors are used in a gas insulated switchgear, if all of the disconnectors are equipped with resistors, major problems arise in terms of increased size, weight, and price.

In view of the above points, the present invention investigates and examines the conditions that require a resistor-equipped disconnect switch in gas-insulated switchgear, and provides protection against overvoltage due to restriking by limiting the installation location of the resistor-equipped disconnect switch. The object of the present invention is to provide substation equipment using a gas-insulated switchgear that is designed to reduce dimensions, weight, and cost while maintaining sufficient characteristics. In order to achieve the above object, in the present invention, only the disconnector installed on the power transmission line side of the disconnector connected between the bus bar and the power transmission line is a disconnector with a parallel resistor. .

The present invention will be explained below with reference to the drawings. An example of a double bus substation will be explained.
An example of the configuration of a substation with four busbar sections, four transformer lines, and four transmission lines is shown in Figure 1 as a single line diagram. Power transmission lines 1a, 1b, 1c, and 1d are overhead lines, and reactors 2a, 2b, 2c, and 2d are connected to their end points. In addition, in the figure, the three phases are collectively expressed as "1a", etc., and the same applies hereinafter. C.L.
are each of these reactors 2a, 2b, 2c, 2d
The parallel ground capacitance of is shown respectively.

3a, 3b, 3c, and 3d are gas insulated conduits or buried cables (hereinafter referred to as gas insulated conduits), which are connected to the main buses 6A and 6O and the overhead power transmission line 1a.
~1d, and line breakers 7a, 7b, 7c, and 7d are connected at the end points on the main bus side.
In addition, disconnectors 11a, 11b, 11c, and 11d are provided on the transmission line side of these disconnectors 7a to 7d, respectively.
And there is a disconnector 12 near the connection with the main bus 6A.
a, 12b, 12c, 12d, and disconnectors 13a, 13b, 13c, 1 near the connection with the main bus 6B.
There is 3d.

The main busbars 6A, 6B are further divided into busbars with disconnectors 8A, 8B and disconnectors 14A, 14 on both sides thereof.
Classified into 6A, 6A B, 6A and 6B by B, 15A, and 15B. Also busbars 6A, 6
Between B and B, busbar communication shiya disconnectors 10A and 10B are used.
and disconnectors 18A and 19 installed on both sides thereof.
A, 18B, and 19B are connected. Furthermore, from the main busbars 6A and 6B, the bank sheath disconnector 9a,
Gas insulated conduit or buried cable (hereinafter referred to as gas insulated conduit) via 9b, 9c, 9d
4a, 4b, 4c, and 4d, and main transformers 5a, 5b, 5c, and 5d are connected to these end points. C is each of these main transformers 5a, 5b, 5c,
The ground capacitance of the main transformer viewed from the primary side of 5d is shown. In addition, disconnectors 16a, 16b, 16c, 16d and 1 are installed between the main buses 6A, 6B and the transformer circuit sheath disconnectors 9a, 9b, 9c, 9d, respectively.
7a, 17b, 17c, and 17d are provided.

Here, in the present invention, line breakers 7a to 7d
Track side disconnectors 11a, 11b, 11c, 11d
Only one is a disconnector with a parallel resistor, and the others are regular disconnectors.

Next, the operation of the present invention will be explained. In the circuit configuration shown in Figure 1, when we investigated the occurrence of overvoltage due to restriking during disconnector operation, we found that the highest value of overvoltage occurred in the simplest case without branches (for example, Figure 2), and Complex circuits (e.g.
It has been found that the higher the value (see figure), the less likely a high overvoltage will occur.

In FIG. 2, the power transmission line d is separated from the bus bar (marked with an x) by the line disconnector 32, and the disconnector 30 is opened (marked with a *). Other unmarked circuit breakers and disconnectors shall be either open or closed. At this time, due to the re-ignition of the disconnector 30, approximately
A surge of 3.1 times occurred (Case 1). The waveform at this time is shown in FIG.

On the other hand, in the circuit with branches shown in FIG.
6 is opened (marked with an x), the main bus 2B is stopped, and the disconnector 40 is opened.・Make sure the markings, disconnectors, and disconnectors are closed. Other no symbols indicate either open circuit or closed circuit. At this time, the overvoltage generated by the re-ignition of the disconnector 40 reached a maximum value of 2.4 times at the edge and disconnector end 41 (Case 2). The waveform at this time is shown in FIG.

FIG. 6 shows an example of a circuit with more branches. When we investigated the state of overvoltage generation due to restriking when the disconnector 60 was opened (x mark) with the front disconnector 61 and the disconnector 62 open (x mark), we found that at the front disconnector end 61. It was 1.9 times higher (Case 3). Cases 1 and 3 are cases of power transmission line disconnection.
Case 2 is a case of disconnection of the bus bar.

The following constants were used in the above calculations. Power transmission line 1
Surge impedance Z _L of a, 1b, 1c, 1d
=300Ω, gas insulated pipe lines 3a to 3d, 4a to 4d,
Surge impedance of main busbars 6A and 6B Z _G , Z _B
is 75Ω, the capacitance CL of reactors 2a to 2d and the capacitance C _B of main transformers 5a to 5d is 15000pF, the length of gas insulated pipes 3a to 3d is 60 m, and
~4d length is 80m, main bus line 6A, 6A B, 6
The length of Otsu A and 6 Otsu B is 80m.

The overvoltage value that occurs in a circuit terminated with an open end or with a large capacitance is:
Since it does not change much with changes in the length of the circuit or the value of the terminal capacitance, the outline can be left as calculated above. On the other hand, since the overvoltage value is usually allowed to be about 2.5 times higher due to the disconnector being re-ignited, only Case 1 poses a problem in the above cases.

FIG. 8 shows a calculated voltage waveform at the time of restriking at the reactor end 31 when a 1 kΩ parallel resistor is inserted in the disconnector 30 in the circuit shown in FIG. In this way, the resistor can completely suppress overvoltage caused by round-trip propagation.

From the above, in the circuit configuration shown in Figure 1, if only the disconnectors 11a, 11b, 11c, and 11d are equipped with parallel resistance, overvoltage caused by restriking occurring in the substation can be sufficiently suppressed, and insulation breakdown can be prevented. It can be prevented. In the embodiment of FIG. 1, the total number of disconnectors is 2.
Only 4 out of 8 units have parallel resistance. In the present invention, the mutual planar arrangement of the power transmission line conduit, transformer conduit, and main bus bar connection conduit of the gas insulated switchgear is not limited to that shown in FIG. Further, the power transmission line conduit may be a coaxial cable.

As described above, according to the present invention, the power transmission line is a disconnector that generates an overvoltage that may cause dielectric breakdown due to re-ignition of the disconnector, that is, a disconnector connected between the busbar and the power transmission line. Since only the disconnect switch installed on the side is a disconnect switch with parallel resistance,
It is possible to provide substation equipment using an advantageous gas-insulated switchgear that can greatly reduce the size, installation area, weight, cost, etc. of the device compared to a case where the total disconnector is equipped with a parallel resistor.

[Brief explanation of the drawing]

FIG. 1 is a single line diagram of a double bus substation showing an embodiment of the present invention, and FIGS. 2 to 7 are diagrams for explaining the effects of the present invention. 6th
The figure is a single connection diagram showing various cases of disconnector opening operation, and Figures 3, 5, and 7 are the same as those in Figures 2 and 4 above.
FIG. 8 is a voltage waveform diagram due to restriking corresponding to the circuit shown in FIG. 1a, 1b, 1c, 1d...overhead power transmission line, 2
a, 2b, 2c, 2d...Reactor, 3a, 3
b, 3c, 3d...gas insulated pipe line, 4a, 4b,
4c, 4d...Gas insulated pipe line, 5a, 5b, 5
c, 5d...Main transformer, 6A, 6B, 6A, 6B...Main bus, 7a, 7b, 7c, 7d
...Shiya Danki, 8A, 8Otsu...Shiya Danki, 9a,
9b, 9c, 9d...Shiya disconnector, 10A, 10B
...Shiya disconnector, 11a, 11b, 11c, 11
d, 12a, 12b, 12c, 12d, 13a,
13b, 13c, 13d...Disconnector, 14A, 1
4B, 15A, 15B, 16a, 16b, 16
c, 16d, 17a, 17b, 17c, 17d...
...Disconnector, 18A, 18B, 19A, 19B...
Disconnector, 30...Disconnector, 31...Reactor end, 32...Shipping breaker, 41...Shipping breaker, 4
0, 42, 43, 44, 45, 46...disconnector,
60, 62...Disconnector, 61...Shiya Disconnector.

Claims (1)

[Claims] 1. In substation equipment that uses gas-insulated switchgear that has a reactor on the transmission line connection side of the busbar, only the disconnector installed on the transmission line side of the disconnector connected between the busbar and the transmission line has a parallel resistance. Substation equipment using a gas-insulated switchgear characterized by having a built-in disconnect switch.