JPS5933715A - Charging current breakage testing circuit for sf6 gas interrupter - 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] This invention is directed to a ground fault caused by a restriking surge when the charging current is cut off in an SF6 gas disconnector in which a disconnection section is housed together with SF6 gas in a metal container at ground potential. This invention relates to a charging current cutoff test circuit for phenomena.

[Technical background of the invention]

In substations, disconnectors are opened and closed for the purpose of disconnecting equipment within the substation from the power system and switching circuits. The disconnector opens and closes while the adjacent circuit breaker is open, and the disconnector then switches on and off a minute charging current in a short line within the substation leading to the interrupter.

Figure 1 shows an example of the configuration of a substation.
, BUS 2 is the bus bar, A, B, CID, E.

F z G t Hp I t J t K , L p
M t N + O is a disconnector, a, b, c, d, e,
f is the breaker, TRJ, TR2 is the transformer, PLJ,
PL2 *PLJ is a power transmission line.

In such a configuration, for example, the disconnector A opens and closes the short line m to the breaker a, and the disconnector opens and closes the line section n when the disconnector E and the breaker are open. In addition, when the disconnector C1E, N, l, and the interrupter f are open, the disconnector I opens and closes the gauze (・〉1). Substations in which SF6 gas disconnectors are used as D include disconnectors A-D and j shown in Fig. 1, and disconnectors a to f1 bus line BUS 1.
, BUS 2, etc. are all housed in a metal container filled with SF and gas, and composite gas insulated substations have only the busbar as an overhead wire.

It is known that when the charging current is cut off by a disconnector, many restrikes occur, resulting in a load-side line-to-ground voltage waveform as shown in FIG. Well, the opening point OC
Almost at the same time, the small charging current is cut off, and at that time, the power supply voltage v1 at the instant of the cutoff remains on the line on the load side.

Since the current voltage 'V1 is alternating current and changes, the difference between the residual voltage of this line and the power supply voltage is applied between the poles of the disconnector. At this time, the disconnector is still in the process of opening, and the inter-electrode insulation recovery is insufficient, and it is re-ignited at the inter-electrode voltage el. Then, since the capacitance of the line is on the order of several hundred to several thousand picofarads, as soon as the flowing transient current attenuates, breaker is established, and the voltage on the load side line is equal to the power supply voltage v2 at that time. remain. Since the power supply voltage v2 changes further, restriking occurs again at the interelectrode voltage e2. Similarly, the interelectrode voltage 83 p 64 1 elt
+ e6 +67 t 118 +"' Repeat the restriking. Since the distance between the poles of the disconnector gradually increases, in many cases the insulation between the poles of the disconnector is ea) ey)...> e2) el. When the power supply voltage recovers and reaches more than twice the peak value, the shutoff is completed without restarting.

A surge voltage is generated during these restrikes.

For example, a phenomenon of restriking occurs at point a in FIG. 2, and when this is expanded in time, it becomes conceptually shown in FIG. 3. The surge voltage at this time has a high frequency because the line on the load side that is opened and closed is short, and in many cases, its fundamental vibration reaches several hundred kHz.

At the time of restriking, a high frequency current flows between the poles of the disconnector. If the disconnector cuts off this high-frequency current at the first current zero point, as shown at point Become. However, this does not occur in real systems. Shutoff is established when the transient current at the time of restriking has sufficiently attenuated, and is shut off after the voltage on the load side line matches the power supply voltage.

Many restrikes occur when the charging current is cut off by a disconnector, but the maximum residual voltage on the line is the peak value of the voltage on the power supply side. When considering the maximum restriking surge, it is sufficient to consider when the power supply side is restriked at the peak value of the power supply voltage and the load side line is restriked at the peak value of the power supply voltage of opposite polarity.

In order to cut off the charging current of a disconnector which exhibits the above-mentioned phenomenon in an actual system, a charging current cutoff test circuit shown in FIG. 4 has been conventionally used.

1 is the SF under test, gas disconnector, 2 is the load side capacitor, 3
is a transformer, 4 is a short-circuit generator, 5 is a reactor, 6 is a capacitor on the power supply side, 7 and 8 are respectively the above-mentioned SF under test, the power supply side of the gas disconnector 1, and the bushing 9 on the load side is a glue for compensating the lead current. It's Akudol.

In such a configuration, the waveform and magnitude of the restriking surge are mainly determined by the load side capacitor 2 and reactor 5.
, is determined by a series circuit of capacitor 6.

In the test circuit shown in FIG.
A voltage waveform similar to the one shown in the figure is obtained. However, if a disconnector applied to an actual system is used as is, its opening speed is fast, so the number of times that restriking occurs is limited. As mentioned above, the surge voltage due to restriking reaches its maximum level when the power supply side and load side of the disconnector are respectively restriked at peak values of opposite polarities of the power supply voltages. This is shown in FIG. 2 at point a- or point b. SF6 gas disconnector 1
Ground faults due to restriking surges are more likely to occur as the surge voltage increases, and ground fault voltages vary and are stochastic. Therefore, if the power supply side and the load side of the disconnector 1 are not always re-ignited at the peak value of the power supply voltage due to one interruption, or if the number of times is small, the interruption may occur many times. Must be tested.

[Purpose of the invention]

This invention increases the number of times that the power supply side and the load side of the disconnector are re-ignited each at the peak value of the power supply voltage, reducing the number of times that the disconnector is shut off, thereby preventing the ground fault phenomenon caused by the re-ignition surge. The purpose of this study is to obtain a charging current and interruption test circuit for SF and gas disconnectors.

[Summary of the invention]

The present invention achieves the above object by configuring the opening speed of the SFa gas disconnector under test to be slower than when applied to an actual system.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. This invention is a test SF6 gas disconnector 1 that lowers the pressure of compressed air for operating the SF6 gas disconnector applied to an actual system, lowers the hydraulic pressure, and lowers the voltage of the electric operated motor. Therefore, the present invention is characterized by using an SF6 gas disconnector 1 having a configuration in which the opening speed is slower than when applied to an actual system.

In the device configured in this way, the voltage waveforms at the load side terminal and power source side terminal of the disconnector obtained by performing a charging current cutoff test are as shown in FIG. As is clear from FIG. 5, the number of times that the power supply side and the load side, where the maximum surge voltage occurs, are each re-ignited at peak values of opposite polarity of the power supply voltage increases. With a small number of interruptions, it is possible to test the ground fault phenomenon of the disconnector against the maximum restriking surge voltage many times.

The opening speed of the above-mentioned sample SF6 gas disconnector 1 is specifically determined from FIG. FIG. 6 shows the charging current and interruption test circuit of the SF6 gas disconnector shown in FIG. It shows the restriking voltage, that is, the discharge voltage waveform, between the electrodes when the comb and the movable electrode are moved and closed. After discharging at the peak value of the power supply voltage at point a shown in FIG. 6, the discharge voltage becomes lower as the distance between the electrodes becomes shorter. At this time, as shown in Figure 6, if the distance between the poles is the discharge start distance between the disconnector poles with respect to the voltage of 2PU, then the distance between the poles is discharged at a voltage of 2PH up to about 0.8L. I understand. In this way, when the period of the AC power supply voltage is T, the movable electrode of the disconnector is 1.0L-0,
8L It would be sufficient to slow down the opening speed by 1-1.

In this way, by setting the opening speed of the movable electrode to 0.2L or less, it is possible to obtain one or more re-ignitions with an inter-electrode voltage twice the peak value of the power supply voltage with one interruption of firing. I can do it.

9- [Effects of the Invention] According to the present invention, it is possible to test the ground fault phenomenon of the disconnector against the maximum restrike voltage many times with a small number of interruptions, and therefore, the number of testing steps can be reduced. It is possible to provide a charging current cutoff test circuit for SF and gas disconnectors.

[Brief explanation of drawings]

Figure 1 is a single-line diagram showing an example of a substation, Figure 2 is a load-side line-to-ground voltage waveform diagram when a disconnector cuts off a small charging current on a short line on the same side, and Figure 3 is a diagram of the load-side line-to-ground voltage waveform of Figure 2. 4 is a diagram showing an example of a charging current cutoff test circuit for a conventional SF6 gas disconnector, and FIG. 5 is a diagram showing an example of a charging current cutoff test circuit for a conventional SF6 gas disconnector. Figure 6 shows the voltage waveforms of the load side terminal and power supply side terminal of the disconnector when a charging current cutoff test is conducted in the charging current cutoff test circuit of the disconnector. In the disconnection test circuit, with the load side capacitor charged with the voltage of the peak value of the power supply voltage, the movable electrode is slowly moved from the open state of the test disconnector 10 to close it, and the repointing between the poles is determined. It is a figure showing an arc voltage waveform. 1... Test SF6 gas disconnector, 2... Load side capacitor, 3... Transformer, 4... AC power supply, 5... Reactor, 6... Power supply side capacitor, 7, 8 ...Bushing, 9...Compensation reactor. Applicant's agent Patent attorney Takehiko Suzue 11- Figure 1

Claims (2)

[Claims] (1) Connect an AC power source to the primary terminal of the transformer, connect a power supply capacitor in parallel to the secondary terminal of the transformer, and connect a reactor and load capacitor in series between both terminals of this power supply capacitor. SF in a metal container at ground potential,
A test SF containing a gas disconnector and first and second bushings that are attached to the metal container and electrically connected to the disconnector; A charging current interruption test circuit for an SF, gas disconnector, characterized in that the opening speed of the test SFg gas disconnector is slower than that when applied to an actual system. (2) L1 is the distance between the poles of the disconnection part at which the poles of the disconnection part start discharging at twice the peak value of the AC voltage on the secondary side of the transformer.
A charging current cutoff test circuit for an SF6 gas disconnector according to claim 1, wherein the opening speed is 0°2L or less when the period of the AC voltage on the secondary side of the transformer is T.