JPH0560062B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a circuit for testing the charging current and disconnection performance of an SF ₆ gas disconnector.

[Technical Background of the Invention] In a substation, a disconnector is opened and closed for the purpose of disconnecting equipment within the substation from the power system, switching circuits, and the like. The opening and closing of a disconnector is performed while the adjacent cable breaker is open, and the disconnector switches on and off a minute charging current in a short line within the substation leading to the cable breaker. Figure 3 shows an example of the configuration of a substation. For example, disconnector A opens and closes a short line m to disconnector a, and disconnector D opens and closes disconnector E and disconnector b. When track section n opens and closes. Further, when the disconnectors C, E, K, N and the bow disconnector f are open, the disconnector I opens and closes the bus bar 1.

Furthermore, gas insulated switchgear filled with SF ₆ gas is widely used in substation equipment due to its excellent insulation performance and ability to be made smaller and smaller. The SF ₆ gas disconnect switch is one such gas-insulated switchgear, and is used in substations that employ various gas-insulated switchgear.

In addition, substations where SF ₆ gas disconnectors are used are:
Figure 3 shows a fully gas-insulated substation in which all disconnectors, disconnectors, busbars, etc. are housed in a metal container filled with SF ₆ gas, and a combined gas-insulated substation with only the busbar as an overhead wire. Broadly classified.

By the way, it is known that when the charging current is interrupted by a disconnector, a large number of restrikes occur, resulting in a load-side line-to-ground voltage waveform 11 as shown in FIG. In addition, in the figure, 12 is a power supply side line-to-ground voltage waveform, and 13 is a restriking surge voltage.

First, the minute charging current is interrupted almost simultaneously with the opening, and at that time, the power supply voltage V ₁ at the instant of the interruption remains on the line on the load side. Since the power supply voltage 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 not sufficient, and it is re-ignited at the inter-electrode voltage _e1 . Then, since the capacitance of the line is on the order of several hundred to several thousand picofurads, as soon as the flowing transient current attenuates, a disconnection occurs, and the voltage on the load side line increases to a level equal to the power supply voltage V ₂ at that time. It remains. Since the power supply voltage changes further, restriking occurs again at the electrode-to-electrode voltage _e2 . Similarly, the interelectrode voltage e ₃ ,
Repeat roll call at e ₄ , e ₅ , e ₆ , e ₇ , e ₈ , etc. Since the distance between the poles of the disconnector gradually increases, if the polarity effect of the discharge starting voltage between the poles is ignored, generally e ₈
＞e ₇ ＞...＞e ₂ ＞e ₁ When the insulation between the poles of the disconnector recovers and the power supply voltage reaches about twice the peak value or more, the restarting and disconnection are completed.

A surge voltage is generated during these restrikes. For example, when the phenomenon of restriking at point a in FIG. 4 is temporally expanded and conceptually illustrated, it becomes as shown in FIG. 5. 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.

Therefore, a high frequency current flows between the poles of the disconnector at the time of restriking. If the disconnector disables this high frequency current
When the current is cut off at the first zero current point as shown at point x in Figure B, the voltage on the load side line remains at the voltage at point y in Figure A. However, such a thing does not occur in a real system. When the transient current at the time of restriking has sufficiently attenuated, a break occurs, and after the voltage on the load side line matches the power supply voltage, the break occurs. 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 this way, when the charging current of the disconnector is cut off, the above-mentioned phenomena such as the occurrence of the restriking surge voltage occur, so conventionally, for example, the circuit configuration shown in Figure 6 is Tests are being conducted to determine whether disconnectors can withstand surge voltages.

In the figure, 1 is a disconnector under test, 2 is a load side capacitor, 3 is a power supply side capacitor, 4 is a reactor, 5 is a transformer, and 6 is an AC power source. The capacitor 2 simulates the capacitance of the load-side line of a disconnector in the field, and in this test circuit, the charging current flowing through the capacitor 2 is directly switched on and off by the disconnector 1 under test. The surge voltage generated when the test disconnector 1 is re-ignited is mainly caused by the load side capacitor 2, the test disconnector 1, the reactor 4,
It is determined by the circuit of the power supply side capacitor 3. In the case of SF ₆ disconnectors, there is a phenomenon in which a ground fault occurs between the poles of the disconnector to the metal container at ground potential due to the surge voltage generated at the time of restriking. We must also pay attention to this phenomenon.
For this purpose, it is necessary to make the surge voltage generated in the test circuit as equal as possible to the surge voltage in the actual system. The power supply side capacitor 3 in FIG. 6 is connected for this purpose. By making the capacitance value of the power supply side capacitor 3 larger than the capacitance value of the load side capacitor 2, a large surge voltage can be generated.

[Problems with Background Art] However, the conventional test circuit as described above has the following problems.

That is, in the test circuit of Fig. 6, the test SF ₆
The magnitude of the surge voltage due to restriking when the charging current is interrupted by a gas disconnector increases as the voltage between the poles where restriking occurs increases; The voltage between the electrodes differs each time the electrode is interrupted, and its maximum value may be obtained many times, for example, 200 times, or only once or twice. Therefore, in order to verify whether a disconnecting switch can withstand the maximum surge voltage that occurs, it is necessary to perform the operation many times until the maximum value is obtained, making the test extremely inefficient. The problem worsened and became a major problem in testing disconnectors.

[Object of the invention] The present invention was proposed in order to solve the problems of the prior art as described above.
The SF ₆ gas disconnector has realized a configuration that allows continuous restriking at the maximum voltage between poles at which restriking occurs when the charging current is cut off, and has been continuously tested under the most severe conditions. The purpose of this paper is to provide a charging current and disconnection performance test circuit for a possible SF ₆ gas disconnector.

[Summary of the Invention] In order to achieve the above object, the present invention connects one terminal of a reactor to the first terminal of a test SF ₆ gas disconnector in which a movable electrode is driven halfway and fixed. A first capacitor and a secondary winding of a first transformer are connected between the other terminal of the reactor and ground, an AC power source is connected to a primary winding of the first transformer, and Connecting a second capacitor between the second terminal of the SF ₆ gas disconnector under test and ground, connecting one terminal of a resistor to the second terminal of the SF ₆ gas disconnector under test, A secondary winding of a second transformer is connected between the other terminal of this resistor and the ground, an AC power source is connected to the primary winding of the second transformer, and an AC power source is connected to the primary winding of the second transformer. The phase difference between the voltage to ground of the secondary winding of the second transformer and the voltage to ground of the secondary winding of the second transformer is 180°.

With such a configuration, the voltage of the second capacitor becomes approximately equal to the voltage of the first transformer every AC half-wave, so that the voltage between the poles at which restriking occurs is the maximum voltage or this value. At voltages above,
Achieves continuous restrike.

[Embodiment of the Invention] FIG. 1 is an explanatory diagram of an embodiment of the invention.
1 is the SF ₆ gas disconnector under test, 2 is the load side capacitor (second capacitor), 3 is the power supply side capacitor (first capacitor), 4 is the reactor, 5 is the power supply side transformer (the first transformer) ), 6 is an AC power supply (first AC power supply), 7 is a load-side transformer (second transformer),
8 is a power supply side AC power source (second AC power source), and 9 is a high resistance body. Note that the voltage phases of transformer 5 and transformer 7 are 180 degrees out of phase with each other.

The operation of this embodiment having the above configuration is as follows.

First, when testing the same circuit,
The movable electrode of the SF ₆ gas disconnector 1 is driven and fixed in the middle, the distance between the electrodes and the fixed electrode is set to a predetermined length, and the discharge starting voltage between the electrodes is set at the maximum pole at which restriking occurs. The voltage is set to a predetermined voltage that is equal to or higher than the current voltage. Then, a voltage is generated in the transformer 5, and further,
The transformer 7 generates a voltage that is approximately the same in voltage and amplitude as the transformer 5 but differs in phase by 180 degrees, and discharges between the poles of the SF ₆ gas disconnector 1 under test.

Then, the voltages at each part of the test circuit become as shown in FIG. In addition, in the figure, 21 is the voltage of the load side capacitor 2, 22 is the voltage of the power supply side capacitor 3, 2
3 is the voltage of the transformer 7, and 24 is the surge voltage.

First, a voltage difference between the transformer 5 and the transformer 7 is applied between the poles of the disconnector, and when this voltage becomes equal to or higher than a predetermined discharge starting voltage between the poles, a discharge occurs. At this time, as in FIG. 6, a surge voltage is generated that is mainly determined by the circuit of the power supply side capacitor 3, reactor 4, sample SF ₆ gas disconnector 1, and load side capacitor 2. Since the resistor 9 has a high resistance, only a small commercial frequency current flows between the transformers 5 and 7 through the poles of the disconnector, and therefore, as explained in FIG. 5, the voltage of the capacitor 2 on the load side However, transformer 5
A break occurs when the voltage becomes approximately equal to the voltage of . Then, the load-side capacitor 2 is charged through the resistor 9 and becomes equal to the voltage of the current transformer 7. Then, when a voltage higher than the discharge starting voltage is applied between the poles of the test disconnector 1 again in the next AC half wave, the test disconnector 1 discharges and generates a surge voltage.

Therefore, at every AC half-wave, the voltage on the second capacitor becomes approximately equal to the voltage on the first transformer, so that the voltage at or above the maximum pole-to-pole voltage at which restriking occurs is continuous. Can be re-ignited.
As a result, it becomes possible to perform continuous testing under the most severe conditions in a single operation, eliminating the need for repeated operations many times as in the past, and greatly improving testing efficiency.

[Effects of the Invention] As explained above, according to the present invention, the simple configuration of providing a high resistance, a second transformer, and an AC power source on the load side allows the disconnector under test to carry charging current. It realizes continuous restriking at the maximum voltage between poles at which restriking occurs or a voltage higher than this when the flame is cut off, and it is possible to perform tests continuously under the harshest conditions, thus increasing test efficiency. We can provide an excellent SF ₆ gas disconnector charging current and disconnection performance test circuit that can significantly improve the performance.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is a waveform diagram showing voltages at various parts of the circuit of the present invention.
The figure is a wiring diagram showing an example of the configuration of a substation, Figure 4 is a waveform diagram showing the occurrence of restriking, Figure 5 is a waveform diagram showing restriking surge voltage, and Figure 6 is a conventional test circuit. FIG. 1... Test SF ₆ gas disconnector, 2... Load side capacitor, 3... Power supply side capacitor, 4... Reactor, 5... Current transformer, 6... AC power supply, 7... Current transformer, 8...AC power supply, 9...High resistance object.

Claims (1)

[Claims] 1. One terminal of the reactor is connected to the first terminal of the SF ₆ gas disconnector under test, in which the movable electrode is driven halfway and fixed with a predetermined distance between it and the fixed electrode. Connect the first capacitor and the secondary winding of the first transformer between the other terminal of this reactor and ground, and connect the AC power to the primary winding of the first transformer. Connect a second capacitor between the second terminal of the SF ₆ gas disconnector under test and the ground, and connect one terminal of the resistor to the second terminal of the SF ₆ gas disconnector under test. connect the secondary winding of the second transformer between the other terminal of this resistor and ground, connect the AC power source to the primary winding of the second transformer, The ground voltage of the secondary winding of the first transformer and the second
The phase difference between the secondary winding of the transformer and the ground voltage is
A charging current and disconnection performance test circuit for an SF ₆ gas disconnector characterized by a 180° angle.