JPS6154808A - Conduit bus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a conduit busbar having characteristics that particularly attenuate sudden wave surge voltages.

[Technical features of the invention and its problems] In recent years, substations (or switchgear) using S Fb gas insulated equipment have made remarkable progress, and have now been put into practical use from the original 66kV class to the 500kV class. S
F6 gas-insulated substations have many advantages, such as being able to reduce the size of the site, being highly safe, and being easy to maintain, so it is likely that they will continue to develop.

In such an SF6 gas-insulated substation, the circuit breaker or disconnector of the SF6 gas-insulated switchgear, which is the main separate equipment that makes up the substation, is opened and closed, and circuits are disconnected or connected. When this occurs, a discharge occurs between the electrodes. The surge voltage generated by this discharge is sometimes more than twice the rated value, and the time it takes to reach the peak value of the first wave becomes a high-frequency vibration wave of 100 n3 or less. In addition, coaxial structures such as conduit busbars, in which the center conductor is concentrically surrounded by busbar ducts, have extremely good frequency characteristics, and are able to propagate voltages at frequencies up to 1GHX (essentially, without attenuation), so they can withstand surges. The signal reaches equipment connected to gas-insulated switchgear, such as bushings and transformers, without being attenuated.

Next, the effect of such high frequency voltage on other devices will be explained using a transformer as an example. FIG. 6 is a schematic cross-sectional view of an assembled transformer connected to a gas insulated switchgear, as a typical example of a conventional GIS substation. The transformer TR stores the contents of the transformer, in which a winding 2 is wound around an iron core 1, together with insulating oil in a tank 3, and is equipped with a cooler 4 for cooling the insulating oil and a conservator 5 for preventing oil deterioration. ing. The transformer lead wire 6 of the winding 2 is passed through the oil duct 7 to the gapless arrester 1.
1, roughly oil/gas bushing 8 to S Fg
The gas line bus duct 9 is connected to a gas switchgear (not shown) via a high-voltage center conductor 10.

Now, in such a configuration, when the switchgear operates, a high-frequency surge with a high rising steepness occurs at the fourth time, and this high-frequency surge is applied to the transformer through the conduit busbar. The response of the transformer winding to such a high frequency surge with a high wave front steepness is as follows. A case will be described in which a high cell cap disk winding shown in FIG. 7, which has excellent impulse voltage resistance characteristics, is used as a transformer winding.

When a high-frequency surge voltage with a steep wave is applied to the Hi-Cell Cap disk winding, the potential distribution seems to improve because the Hi-Cell Cap winding has a large series capacitance constant, but this is not the case in reality. That is, in Figure 7, the series capacitance is the voltage applied to the first turn of the first stage plus half of the total turns N=16 of the second stage, plus N/2=8. It is the first thing that is formed. However, when the voltage becomes a steep wave surge, the voltage wave that enters the first turn becomes N/2.
The peak value will be reached in the first turn before reaching the next turn with . In response to such a steep surge voltage, the improvement of the potential distribution, which is the aim of the high cell cap disk winding, becomes meaningless. This pointless boundary varies depending on the voltage and capacity of the winding, but it is said that the time required to reach the negative peak value of the -th wave is about 0.5 μs or less.

In this way, the transformer is defenseless against high-frequency surges with a steep rise even if a vial winding with good lightning impulse characteristics is used. Now, let us consider whether the lightning arrester 11 can operate and protect the transformer. Now, suppose that a high frequency surge enters the conduit busbar 9 due to the operation of the switch. A waveform diagram of the steep wave voltage at each part at that time is shown in FIG. First, a steep wave voltage with a voltage wave height (E) charges the ground capacitance CO of the oil/gas bushing 8 and reaches the terminal of the lightning arrester 11.At this time, the ground capacitance CO of the bushing 8
Therefore, the peak value of the steep wave voltage becomes slightly smaller E', and the wave front steepness also becomes slightly smaller. In the lightning arrester 11, the v-
Since the current flows according to the i-characteristic, the voltage is suppressed below the limit voltage of the lightning arrester 11, and its peak value becomes E LL. However, since the surge arrester only lowers the peak value without changing any part of the wave front steepness, it is not possible to improve the above-mentioned problem, that is, the winding distribution in the transformer winding 2 of the steep wave surge voltage.

[Object of the invention] The object of the present invention is to provide an S Fb gas insulated substation with
It is an object of the present invention to provide a conduit bus bar that prevents equipment such as a transformer from suffering dielectric breakdown due to high frequency surges generated by the operation of an Fg gas insulated switchgear.

[Summary of the Invention] A conduit busbar according to the present invention is characterized in that a ferromagnetic material is attached around a central conductor.

[Embodiments of the Invention] The present invention will be described below with reference to an embodiment shown in FIG. In FIG. 1a and b, a conduit busbar 20 according to the present invention is constructed by surrounding a central conductor 10 with a conduit busbar duct 9, and filling the interior with SF and an insulating gas. In the present invention, d3 has a ferromagnetic material 1 on the surface of the center conductor 10.
2 is attached by plating or soldering. This strong +41
As the magnetic substance 12, for example, iron, cobalt, nickel, or rare earth cobalt magnet alloy is used.

Next, the operation of the pipe busbar 20 according to the present invention is explained using the SF diagram in FIG.
c. The case where it is used in a gas insulated separate container will be explained. Generally, when a high frequency wave generated by the operation of a disconnector or the like propagates through a conventional conduit busbar, the electric field EO in the conduit busbar has a radial direction, and the magnetic field ΦO has a radial direction as shown in FIG. 2a. It moves in a circular direction with the same central axis.

At this time, as shown in FIG. 2, the closer the magnetic flux Φ0 is to the center conductor 10, the stronger the magnetic flux Φ0 becomes.

On the other hand, in the conduit busbar 20 according to the present invention, a ferromagnetic material 12 is provided on the surface of the center conductor 10.
When magnetic flux is applied, a spontaneous magnetic field is generated according to the magnetic susceptibility. Here, when the magnetic flux is alternating current, the spontaneous magnetic field follows the external magnetic flux and changes, but as the frequency of alternating current increases, the spontaneous magnetic field cannot fully follow the external magnetic flux, causing a delay, and the third
Draw the hysteresis shown in the figure.

The area surrounded by this hysteresis becomes a loss and dissipates as heat. The higher the frequency, the higher the loss proportionally. For example, as an example of the ferromagnetic material 12, Fc
, Co, Ni 5Fe3C carbon steel, Alnico 5, barium ferrite, and rare earth cobalt magnet alloy, regardless of V3, (the saturation magnetic field gradually increases, and the high frequency energy in one cycle of the hysteresis curve increases. Attenuation increases.

On the other hand, at high frequencies, current only flows near the surface due to the skin effect. The epidermal depth is used as a guideline.

The skin depth here refers to the current density value of 1/e on the metal surface.
is the depth of the surface/p + et al. Magnetic flux accompanies electric current, and magnetic flux exists only near the surface, and its approximate value is the skin depth. In FIG. 4, the skin depth δ of the center conductor 10 is given by the following formula.

ρ: Resistivity of material (Ω/m) r: Frequency For example, for iron, at a frequency of 1 MHz, δ', 160
At a frequency of 1 MHz or more, the skin depth is about 160 μm or less. Therefore, when the ferromagnetic material 12 is iron, high frequencies can be sufficiently attenuated by applying iron plating or foil of about 160 μm to the center conductor 10. In this way, by plating or vapor depositing the magnetic substance 12 to about the skin depth of IMl-h, or by attaching a foil having a thickness of about the skin depth to the center conductor 10,
High-frequency voltage can be sufficiently attenuated, and an inexpensive and highly reliable pipe bus can be easily obtained.

Further, according to the present invention, since the surface of the center conductor of the conventional conduit busbar is plated with ferromagnetic material or a number is attached with foil, the work can be easily performed. In general, in the present invention, only the high frequency components are attenuated, and there is no concern that commercial frequency voltage will be attenuated or heated, so a conduit bus bar that can attenuate high frequency voltage without impairing reliability can be obtained. It will be done.

FIG. 5 shows another embodiment of the invention.

A ferromagnetic foil 12 and a polymeric material or ceramic coated with the ferromagnetic material 12 are arranged in a multi-cylindrical shape concentrically lN1 with the center conductor 10. By doing this,
When high frequency waves propagate through regions divided by ferromagnetic materials 12, the number of ferromagnetic materials 12 in contact with each region increases by the number of foils 12, and the damping effect on high frequencies can be increased.

[Effects of the Invention] As described above, according to the present invention, high frequency surge voltage can be attenuated efficiently at low cost and with high reliability due to the effective combination of the center conductor and the ferromagnetic material. The pipe busbar can be (n).

[Brief explanation of the drawing]

Figures 1a and b are cross-sectional views and vertical cross-sectional views showing one embodiment of a conduit busbar according to the present invention, and Figures 2a and b are directions of the electric field when a high-frequency surge propagates to a conventional conduit busbar. FIG. 3 is a characteristic diagram showing the hysteresis curve of a ferromagnetic material, FIG. 4 is an enlarged sectional view of the central conductor portion of the conduit busbar of the present invention, and FIG. 5 is a diagram of the center conductor of the present invention. A cross-sectional view showing another embodiment, FIG. 6 is a schematic 41'4 diagram without showing a commonly used gas-insulated substation, and FIG. 7 is a configuration diagram showing a high cell cap winding of a transformer. FIG. 8 is a 11Q-:j characteristic diagram showing the attenuation state accompanying the propagation of a surge voltage generated in a conventional switchgear. TR...Transformer, 1...Transformer core 2.
...Transformer winding, 3...Transformer tank 6...
High voltage lead wire 7... Lead wire duct j- 8... Oil/gas bushing 9... Gas pipe busbar duct 10... Center conductor, 11... Lightning arrester 12... Ferromagnetic material, 20 ...Pipeline Bus Line (8733) Agent Patent Attorney Yoshiaki Inomata (and 1 other person) #, Figure 1, Figure 2, i. Figure 3 Figure 4 Figure 5 Figure 6

Claims (4)

[Claims] (1) A gas-insulated pipe bus connected to a gas-insulated switchgear, characterized in that a ferromagnetic material is provided around the center conductor. (2) The pipe busbar according to claim 1, wherein a ferromagnetic substance is attached to the surface of the central conductor by vapor deposition or plating. (3) A conduit busbar according to claim 1, characterized in that a ferromagnetic material is made into a foil and provided coaxially in the form of multiple cylinders around the central conductor. (4) As ferromagnetic substances, especially Fe, Co, Ni,
Fe_3O, MuBi, MuSb, carbon steel, alnico 5
(Co-Ni-Al-Cu alloy), barium ferrite (BaO.6Fe_2O_3), rare earth cobalt magnet alloy (SnCo_5), and manganese zinc ferrite. Conduit busbar.