JPS6348368B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes the merits of each arc extinguishing method by configuring a shredder breaker with a vacuum shield section and a gas shield section that employ different arc extinguishing methods. Taking advantage of
The present invention relates to a breaker designed to cover the drawbacks.

In recent years, with the increase in high voltage and capacity in power systems, the short circuit current that must be cut by a short circuit breaker has rapidly increased, and the voltage has also tended to increase further. The cable breakers connected to these large-capacity systems have no choice but to have a configuration in which a large number of cable breakers are connected in series.
In this case, the number of parts was large, and this was not necessarily desirable from the standpoint of improving system reliability. Efforts are being made to reduce the number of test and break points.

By the way, the most severe conditions among the responsibilities that an AC switch or disconnector must perform are terminal short-circuit failures and short-distance line failures. Here, the terminal short-circuit fault must suppress the maximum short-circuit current, but
The rate of rise in the re-electromotive voltage is sufficiently low compared to short-distance line faults, and the phenomenon in which shearing fails is so-called dielectric breakdown restriking due to the high voltage. For such a phenomenon, a so-called gas shield disconnector that involves spraying of gas is very suitable, and can provide excellent withstand voltage characteristics per disconnect point. On the other hand, the voltage performance of a vacuum disconnector is approximately 1/3 that of a gas disconnector.
It's nothing more than that.

On the other hand, in the case of a short-distance connection line failure, the rate of increase in the restart voltage after the current is interrupted is very high, and the phenomenon when the interruption fails is what is called thermal re-ignition.
This has a close relationship with the current drop rate before the current zero point, and the success or failure of shearing is determined within a few μs after the current zero point. With regard to such phenomena, vacuum insulation and disconnectors have approximately three times better performance than gas insulation and disconnection.

Recently, there has been a strong need for the development of direct current and circuit breakers, which have been developed to forcibly inject current from other capacitor power sources during power outages to create a current zero point. For economical reasons, it is desirable to make the capacitance of the capacitor as small as possible. When the capacitor capacity is made smaller, the rate of drop in current increases and the rate of increase in restart voltage also increases. Therefore, it is necessary to use a vacuum circuit breaker that has excellent performance against the thermal re-ignition phenomenon, and in this sense, a vacuum circuit breaker is the best option, as it is for short-distance line failures mentioned above. Are suitable. However, DC and disconnectors used in DC power transmission systems are required to be up to around 500KV, just like in the case of AC, and vacuum disconnectors must have a multi-point disconnection structure from the standpoint of withstand voltage performance. I don't get it. On the other hand, although gas shield disconnectors have excellent withstand voltage performance, as mentioned above, they do not have the same performance as vacuum disconnectors in terms of thermal re-ignition phenomena, so the rate of rise in the re-EMF voltage per circuit break is limited. In order to lower this, a multi-point cutting structure must be used. In order to avoid a multi-point disconnection structure with gas insulators and disconnectors, it is possible to increase the capacitance of the capacitor to lower the rate of current drop and the rate of increase in re-electromotive voltage, but this cannot be said to be economical.

As mentioned above, in both AC and DC circuits, when a circuit breaker with ultra-high pressure or higher is configured with only a gas or vacuum section or a vacuum section or a section,
A multi-point cutting structure had to be used, which was not only uneconomical but also required a large number of parts, which was not desirable from the standpoint of improving reliability.

As a means to solve these problems, a method has been considered that connects a vacuum shield and gas disconnector in series to cover the shortcomings of both and take advantage of their strengths, but this method does not yield optimal performance. In order to do this, it is necessary to divide the re-electromotive voltage applied after the shield is broken into the vacuum shield section and the gas shield section into values suitable for the performance of each.

Conventionally, in so-called multi-point disconnectors or disconnectors in which multiple shields are electrically connected in series, a resistor is connected in parallel to each shield in order to equalize the voltage sharing among these shields as much as possible. Alternatively, only a capacitor is connected, and a resistor voltage division type or capacitor voltage division type voltage distribution method has been adopted, in which the voltage distribution of each shear and disconnection portion is always constant over time with respect to the re-EMF voltage waveform.

Figure 1 shows an example of the re-EMF voltage waveform when a short-distance line fault occurs in an AC power transmission system. The portion 1 is due to the re-electromotive voltage generated on the line side, and because the frequency is high, the rate of increase in the re-electromotive voltage is very high, but the voltage value in this portion is sufficiently low compared to the overall re-electromotive voltage. Part 2 is due to the re-electromotive voltage generated on the power supply side, and has a very high voltage peak value. If we adopt the above-mentioned capacitor voltage division type or resistor voltage division type voltage sharing method for this kind of re-electromotive voltage, the waveform applied to each cross section will simply be similar to that in Figure 1. As explained above, it is clear that a vacuum shield and disconnector simply constructed by connecting a vacuum shield and a gas shield in series is meaningless.

SUMMARY OF THE INVENTION An object of the present invention is to provide a shear breaker that can obtain excellent shear breaker performance by adjusting the re-electromotive voltage to an optimal value.

FIG. 2 shows a circuit diagram of the present invention. A vacuum shield section 7 consisting of a vacuum shield disconnector and a gas shield section 8 consisting of a buffer type gas shield disconnector are connected in series, and a resistor is connected in parallel to each shield section 7 and 8. Connect 3 and 4. Capacitors 5 and 6 are further connected in parallel to the resistors 3 and 4. Also, resistance 3
The value of is smaller than the value of resistor 4, and the value of capacitor 5 is also smaller than the value of capacitor 6. That is, resistance value 3<resistance value 4, capacitor capacity 5<capacitor capacity 6.

By forming the shield breaker with such a configuration, most of the voltage with rapid time changes is applied to the vacuum shield breaker 7 through the capacitor voltage dividing section, and the voltage that is accompanied by rapid time changes is applied to the vacuum shield breaker 7 through the capacitor voltage dividing section, and the voltage that is accompanied by rapid time changes is applied to the vacuum shield breaker 7 through the capacitor voltage dividing section. is hardly applied, or even if it is applied, it can be at a very low value. In addition, it is possible to apply most of the voltage with little time change or direct current voltage to the gas shield or disconnection section 8 using the resistive voltage divider, and to apply almost no voltage to the vacuum shield or disconnection section 7. can.

In the waveform example of a short-distance line fault shown in Figure 1,
As shown in FIG. 3, the waveform portion 1 with a high initial rise rate of the re-electromotive voltage is applied to the vacuum shear break portion 7, but subsequent high voltage values are hardly applied. Also, as shown in FIG. 4, almost no voltage is applied to the gas shield section 8 in the initial part where the rate of increase is high, and thereafter the voltage is applied to the part 2 where the rate of increase is low but the voltage is high. become. That is, as described above, it is possible to apply a voltage waveform most suitable for each performance of the vacuum shield section 7 and the gas shield section 8.

Moreover, the sharing ratio of these voltage values can be obtained relatively freely by changing the values of each element.

As described above, by employing the structure of the present invention, it is possible to minimize the number of shear breakage points and provide a sheath breaker with excellent shear cutting performance.

Further, in this example, a case has been described in which one vacuum shield section and one gas shield section are used, but a plurality of these shield sections may be used.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of a re-electromotive voltage waveform in the case of a short-distance line fault, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Figs. FIG. 4 is an explanatory diagram showing a voltage waveform of a gas line break section and a voltage waveform of a gas line break section. 1, 2... Restart voltage, 3, 4... Resistance, 5, 6
...Capacitor, 7...Vacuum shield section, 8...Gas chamber section.

Claims (1)

[Claims] 1 In a circuit breaker constructed by electrically connecting a vacuum shield section and a gas shield section in series, a voltage sharing element consisting of a resistor and a capacitor in parallel is installed in each shield section. The resistance and capacitance values of these elements are set so that the element attached to the vacuum shield section is smaller than the element attached to the gas shield section. Disconnector.