JPH08321234A - High speed grounding switch - Google Patents

Abstract

PURPOSE: To provide a high speed grounding switch which can prevent fusion and damage of a peripheral shield of a stationary contacting piece caused by arcs at the time of zero-miss current breaking over several cycles and is equipped with a high reliability through preclusion of a drop of the ground insulating performance. CONSTITUTION: By means of fusion spray, a coating 21 of alumina (Al2 O3 ) is applied to the inside and outside surfaces of a shield 14 provided at the periphery of a stationary contacting piece 13 and the surface on the side with a movable contacting piece 9. Arcs 20 of several cycles approximately may be produced between the stationary contacting piece 13 and movable contacting piece 17 at the time of zero-miss current breaking, and there is no risk that the arcs 20 transfer to the shield 14 side even though they touch the shield 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage power transmission line for electric power, and when a one-line ground fault occurs due to a reverse flashover (reverse flashover) that occurs between insulator-lined arc horns of the transmission line, the transmission of the power is performed. The present invention relates to a high-speed grounding switch used for reclosing a line at high speed, and in particular, when a zero-miss current is interrupted for several cycles, an arc generated between the movable electrode and the fixed electrode causes the shield around the fixed contact to be shielded. This relates to a high-speed grounding switch that can prevent melting and damage.

[0002]

[Prior art]

(1) Power transmission system protection system-single-phase reclosing method In general, when lightning strikes a power transmission line, a reverse flashover (reverse flashover) occurs in an arc horn of an insulator string suspended on the power transmission line. Most of the accidents that occur on power lines are single-line ground faults caused by this reverse flashover. In order to eliminate such a failure due to a ground fault, the failure section may be set to have no voltage and the reverse flashover, which is the cause of the accident, may be extinguished.

As a concrete protection system of the power transmission system,
It is effective to install circuit breakers for transmission lines at both ends of the transmission line and to cause circuit breakers at both ends of the failed transmission line to perform reclosing operation. The reclosing operation of the circuit breaker is to open the circuit breaker to eliminate the voltage in the faulty section to extinguish the reverse flashover, and then perform the closing operation of the circuit breaker again. By performing such a reclosing operation, it is possible to perform re-power transmission without a power failure. A typical method of reclosing is a single-phase reclosing method. This single-phase reclosing method is widely used because it has little fluctuation in power and excellent transient stability.

(2) Power transmission system protection system equipped with high-speed grounding switch By the way, in recent years, the demand for electric power has been increasing, and along with this, UHV power transmission lines such as 1100 kV are used as high voltage power transmission lines. . When a single-phase reclosing circuit is performed in this UHV system transmission line, electrostatic electromagnetic induction received from another phase of the same line or another line connected together becomes larger than in the case of the conventional 500 kV system. When the electrostatic induction from the other phase becomes large, when the reverse flashover of the insulator arc horn occurs, the reverse flashover is extinguished even if the circuit breakers at both ends of the faulty section are opened. Becomes difficult to do.

Therefore, in a high-voltage power transmission line such as a UHV system, a high-speed grounding switch is installed in the one-line ground fault phase of the high-voltage power transmission line in order to extinguish reverse flashover. That is, after disconnecting the location of the accident from the power transmission line by the circuit breakers at both ends, by turning on this high-speed grounding switch at high speed in cooperation with the switching operation of the circuit breaker, the electromagnetic induction current that continues in the insulator arc horn. The arc is extinguished, and the opening operation is immediately performed to interrupt the induced current, enabling re-power transmission by reclosing the circuit breaker.

A protection system employing this high-speed grounding switch will be specifically described below with reference to the drawings. FIG. 2 is an explanatory diagram showing the configuration of this system. In the figure,
Reference numeral 1 is a bushing and 3 is a UHV type steel tower. 2 is a high-voltage power transmission line, which has three lines of an upper phase, a middle phase, and a lower phase,
It is stretched between the bushing 1 and the tower 3 or between the towers 3. Each steel tower 3 is provided with an insulator string 3b provided with an arc horn 3a, and the power transmission line 2 is suspended from the steel tower 3 by the insulator string 3b. A circuit breaker GCB and a high-speed grounding switch HSGS are provided at both ends of a certain section of the power transmission line 2. Note that 4 is a thundercloud and 5 is a thundercloud.

The operation of the protection system as described above will be described with reference to FIG. FIG. 3 is a sequence diagram for explaining the operation sequence of the circuit breaker GCB and the high-speed grounding switch HSGS when a one-line ground fault accident occurs due to the reverse flashover 3c.

Before the occurrence of the ground fault accident, the circuit breaker GCB is in the closed state and the high-speed grounding switch HSGS is in the open state. In such a state, when a thunder cloud 4 strikes one line with the three-line power transmission line 2, a reverse flashover 3c occurs in the arc horn 3a of the insulator string 3b that suspends the power transmission line 2. . Through the reverse flashover 3c, the transmission line 2
A ground fault current flows from the tower to the steel tower 3, causing a ground fault.

When a ground fault occurs in the power transmission line 2 in this way, the circuit breaker GCB first performs the opening operation after the elapse of T1 time which is the time for the transmission line protection relay. However, the accident transmission line 2
, An induction current flows by electrostatic electromagnetic induction from the other phase,
As a result, the reverse flashover 3c is still maintained between the arc horns 3a. Therefore, circuit breaker GC
When B is open, the high-speed grounding switch HSGS forcibly performs the closing operation at high speed to guide the induced current grounded in the arc horn 3a portion to the high-speed grounding switch HSGS side. This extinguishes the reverse flashover of the arc horn 3a. The high-speed earthing switch HSGS continues to be in the open state for θ time to extinguish the reverse flashover, then returns to the open state to interrupt the induced current, and finally the circuit breaker GCB performs the closing operation to restart the power transmission.

(3) Timing of the opening operation in the high-speed earthing switch Next, the ground fault current and the current flowing in the high-speed earthing switch HSGS will be described with reference to FIG. 4, and the opening operation in the high-speed earthing switch HSGS will be described. The timing of will be described.

As described above, the power transmission line 2 has an upper phase, a middle phase, and a lower phase, and a predetermined load current flows in each phase. In the middle phase of the power transmission line 2, when T01 is a ground fault accident, T02 is a fault current interruption of the circuit breaker GCB, and the middle phase of the power transmission line 2 is between T01 and T02. Only the accident current flows.

However, since the middle phase of the power transmission line 2 receives electrostatic electromagnetic induction from the upper and lower phases which are other healthy phases and other lines that are connected in parallel, the circuit breaker GCB is open. ,
Reverse flashover due to the induced current still occurs in the arc horn 3a. At this time, in order to extinguish the reverse flashover, the high-speed ground switch HSGS
When the power is turned on, the ground fault fault current and the electromagnetic induction current, which initially contain the DC component, are superposed after the turn-on time T03, and a current shifted from the current zero point flows. After that, as the ground fault accident current is grounded, the electromagnetic induction current component increases and an alternating current passing through the current zero point flows.
That is, when the high-speed grounding switch HSGS is used to interrupt the electromagnetic induction current, it is necessary to catch the timing when the current becomes zero and perform the opening operation.

(4) High-speed earthing switch having a puffer type arc-extinguishing chamber However, the above electromagnetic induction current reaches 7,000 A, and when the current is cut off, the transient phenomenon of the electric circuit and the faulty power transmission line are generated. A transient recovery voltage of up to 900 kV superposed with the electrostatic induction voltage received from another line is applied. Such a comparatively large current, and a comparatively large rate of rise and a high peak value in the transient recovery voltage condition cause interruption in a parallel-type grounding switch that simply opens and closes the contact in SF ₆ gas. Can not do it. Therefore,
In the case of performing such interruption, a high-speed grounding switch having a puffer-shaped arc extinguishing chamber is required like the circuit breaker.

A conventional example of a high-speed grounding switch having a puffer type arc extinguishing chamber will be described with reference to FIGS. 5 and 6. As shown in FIG. 5, the high-speed grounding switch is provided with a grounding container 6 filled with insulating gas. A conductor 7 connected to the power transmission line side is provided inside the grounding container 6, and a fixed contact portion 8 is provided at a part of the conductor 7. A movable contactor portion 9 is disposed in a portion facing the fixed contactor portion 8, and the movable contactor portion 9 and the fixed contactor portion 8 constitute a puffer arc extinguishing chamber 10. A ground terminal portion 11 is provided near the movable contact portion 9 so as to penetrate the ground container 6. The grounding terminal portion 11 is electrically connected to the movable contactor portion 9 and is connected to the conductor 7 via the puffer arc extinguishing chamber 10 when the high speed earthing switch is closed.

Next, the structure of the puffer type arc extinguishing chamber 10 shown in FIG. 5 will be described with reference to FIG. Note that FIG. 6 shows a fully opened state. As shown in FIG. 6, the fixed contactor portion 8 includes a fixed contactor 13 and a shield 14. Further, the movable contactor portion 9 includes a cylindrical operation rod 15 connected to an operation device (not shown), a puffer cylinder 16 and a puffer cylinder 16.
The movable contactor 17 and the insulating nozzle 18 are mounted on the puffer cylinder 16. A puffer piston 19 is inserted in the puffer cylinder 16, and the puffer piston 19 is fixed to the grounding container 6. And the fixed puffer piston 19
On the other hand, the puffer cylinder 16 and the movable contact 1
7 and the insulating nozzle 18 are configured to move integrally.

The operation of such a puffer type arc-extinguishing chamber 10 is as follows. That is, during the contact opening operation, the gas in the puffer cylinder 16 is compressed and the insulating nozzle 1 at the tip end is compressed.
A gas flow as shown by a dotted arrow in the figure is generated at the 8th part. This gas flow is blown onto the arc 20 generated between the fixed contact 13 and the movable contact 17, and the arc 20 is extinguished.

(5) Zero-miss current interruption performance in high-speed earthing switch When the current is interrupted by the high-speed earthing switch,
At another phase adjacent to the transmission line, for example, the upper phase of FIG.
In 4, when a follow-up failure with a large DC current component occurs, an induction current with a large DC current component generated by electromagnetic induction due to a fault current in the upper phase flows in the middle-phase transmission line. Therefore, as shown in part A of FIG. 4, a zero-miss current that does not form a current zero flows in the middle-phase high-speed grounding switch. In the longest state, the zero-miss current flows until the fault current in the follow-up failure phase is interrupted, which may be about 4 cycles.

On the other hand, in consideration of the breaking current and the transient recovery voltage specification at breakage required for the high-speed earthing switch, it is necessary to drive at a speed comparable to that of the circuit breaker. The stroke end is reached in about 2 cycles. However, due to the extinction mechanism of alternating current,
It is difficult to extinguish the arc except at the current zero point.

Therefore, the high-speed grounding switch is required to have a zero-miss current interruption performance for continuing arc discharge between the fixed contact 13 and the movable contact 17 in the fully opened state. In order to achieve such zero-miss current interruption performance, for example, as shown in Japanese Patent Application Laid-Open No. 6-84436, a space that is not compressed is provided in the puffer chamber and gas is blown to the arc even after the end of the opening operation. A high-speed grounding switch that continues is proposed.

[0020]

However, the high speed earthing switch having the zero-miss current interruption performance as described above has the following problems. That is, since the gap length between the fixed contact 13 and the movable contact 17 requires a UHV class insulation distance, it is a longer gap than a normal gas circuit breaker. Therefore, the arc in the fully opened state may meander (loop) due to the electromagnetic force due to the breaking current, and may come into contact with the shield 14 on the outer circumference of the fixed contact 13. When the arc contacts and transfers to the shield 14, the shield 14 is melted and damaged. As a result, there arises a problem that the ground insulation performance of the high-speed grounding switch is deteriorated.

The high-speed grounding switch of the present invention has been proposed in order to solve the problems of the prior art as described above, and its main purpose is to fix it by an arc when breaking a zero-miss current for several cycles. It is to prevent melting and damage of the contact outer circumference shield, prevent deterioration of insulation performance against ground, and ensure high reliability.

Another object of the present invention is to prevent the transfer of an arc to the shield around the fixed contact.
Yet another object of the present invention is to reduce damage to the shield surface due to arcs.

[0023]

In order to achieve the above object, a high speed earthing switch according to claim 1 is provided with a conductor arranged in a grounding container filled with an insulating gas and the conductor. The fixed contactor, the movable contactor provided to face the fixed contactor, the puffer cylinder that moves together with the movable contactor, and the puffer piston provided inside the puffer cylinder. The puffer chamber is formed in the space between the piston and the puffer cylinder, and the arc generated between the fixed contact and the movable contact when the insulating gas in the puffer chamber is compressed by the puffer piston during the opening operation of the movable contact. In a high-speed grounding switch that blows on and extinguishes arcs, an inorganic insulator is coated on the surface of a shield provided around the fixed contact.

A high speed earthing switch according to a _second aspect of the present invention is characterized in that the inorganic insulator contains alumina (Al ₂ O ₃ ).

A high-speed grounding switch according to a third aspect of the invention is characterized in that the inorganic insulator contains magnesium oxide (MgO).

A high-speed earthing switch according to a fourth aspect is characterized in that the inorganic insulator contains zirconia (ZrO ₂ ).

According to a fifth aspect of the present invention, there is provided a high-speed grounding switch, wherein a conductor arranged in a grounding container filled with an insulating gas, a fixed contact provided on the conductor, and a fixed contact facing the fixed contact. A movable contactor provided, a puffer cylinder that moves together with the movable contactor, and a puffer piston provided inside the puffer cylinder are provided, and a puffer chamber is formed in a space between the puffer piston and the puffer cylinder. In the high-speed earthing switch that extinguishes the arc generated between the fixed contact and the movable contact by compressing the insulating gas in the puffer chamber by the puffer piston during the opening operation of the movable contact, the fixed contact It is characterized in that the surface of a shield provided around the child is coated with a refractory metal.

A high-speed grounding switch according to claim 6 is characterized in that the refractory metal is molybdenum (Mo).

A high-speed grounding switch according to a seventh aspect is characterized in that the refractory metal is tungsten (W).

[0030]

The operation of the present invention having the above construction is as follows. That is, claim 1, claim 2, claim 3,
According to the invention of claim 4, by coating the shield on the outer periphery of the fixed contact with an inorganic insulator,
The arc generated between the movable electrode and the fixed electrode does not transfer to the shield side.

Further, in the inventions of claims 5, 6, and 7, since the refractory metal is coated on the shield on the outer circumference of the fixed contact, the arc generated between the movable electrode and the fixed electrode is shielded. Even if it is transferred to the side, since the coated part has a high melting point, damage due to melting can be minimized.

[0032]

【Example】

(1) Configuration of Embodiment An embodiment of the high-speed grounding switch according to the present invention will be specifically described below with reference to FIG. FIG. 1 is a detailed configuration diagram of an arc extinguishing chamber of a high speed earthing switch according to an embodiment of the present invention. The same parts as those of the conventional technique shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, the present embodiment is characterized in that the inner and outer diameter surfaces of the shield 14 provided on the outer circumference of the fixed contact 13 and the surface on the movable contact 9 side are sprayed with alumina (Al).
₂ O ₃ ) coating portion 21 is provided. Alumina (Al ₂ O ₃ ) is an inorganic insulator having a melting point of about 2300 K and a volume resistivity of about 10 ¹³ Ω · cm, and does not melt or carbonize even when exposed to the arc 20 for several cycles. In this regard, the applicant of the present invention has proposed that J
Arc resistance time according to EC-149-1978 is about 24
It has been experimentally confirmed that the arc resistance time of alumina (Al ₂ O ₃ ) is 420 seconds or more, while it is 0 seconds.

(2) Operation and effect of the embodiment According to the embodiment as described above, the arc 20 of several cycles generated between the fixed contact 13 and the movable contact 17 at the time of interruption of the zero miss current described above. However, even if the shield 14 is touched, the shield 14 has a coating portion 21
Since the arc is applied, the arc 20 does not transfer to the shield 14 side. Therefore, it is possible to prevent melting and damage of the shield 14 due to the arc 20 when the zero-miss current is cut off. As a result, it is possible to prevent deterioration of the ground insulation performance of the high-speed grounding switch, and to ensure high reliability.

Further, in this embodiment, since the coating portion 21 is formed by thermal spraying, the alumina (Al ₂ O ₃ ) film can be easily and inexpensively formed on the curved surface of the shield 14.

(3) Other Embodiments The present invention is not limited to the above embodiments,
For example, although the material of the coating portion 21 is alumina (Al ₂ O ₃ ) in the above embodiment, magnesium oxide (M 2
Similar effects can be obtained by using gO), zirconia (ZrO ₂ ), or a mixture of alumina and magnesium oxide or zirconia. In addition, magnesium oxide (Mg
O) has a melting point of about 3100K and a volume resistivity of about 10
¹¹ Omega · cm or more, the melting point of zirconia (ZrO ₂₎ is about 3000K, the volume resistivity is about ¹⁰ 10 Ω · cm or more.

Further, the coating material of the shield 14 in the present invention is not limited to the inorganic insulating material, and tungsten (W) having a melting point of about 3700K,
Also included are refractory metals such as molybdenum (Mo), which also has a melting point of about 2900K. In this case, the arc 20
May transfer when it touches the coating 21 on the surface of the shield 14, but since the coating material has a high melting point, damage due to melting is slight, and it is possible to prevent deterioration of the ground insulation performance. Further, it is possible to easily and inexpensively coat the surface of the shield 14 with the above-mentioned high melting point metal by thermal spraying.

[0038]

As described above, according to the present invention, by coating the shield surface on the outer periphery of the fixed contact of the high speed earthing switch with an inorganic insulator or a refractory metal, a zero-miss current is cut off for several cycles. In the above, it is possible to provide a highly reliable high-speed grounding switch which prevents the fixed contact outer peripheral shield from being melted and damaged by an arc and which does not deteriorate the withstand voltage performance with respect to ground.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an arc extinguishing chamber in a high-speed grounding switch according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of a protection system that employs a high-speed grounding switch.

[Fig. 3] Circuit breaker (GCB) and high-speed grounding switch (HSG) in the event of a one-line ground fault due to reverse flashover
Operation sequence diagram showing the operation sequence of S)

FIG. 4 shows a high-speed grounding switch (H) when a ground fault occurs in one phase of a transmission line and a follow-up failure accident occurs in another phase.
(SGS) and current waveform diagram showing changes in current flowing in each phase of the transmission line

FIG. 5 is a structural diagram of a conventional high speed grounding switch.

6 is a configuration diagram of an arc extinguishing chamber in the high speed earthing switch of FIG.

[Explanation of symbols]

 GCB ... Circuit breaker HSGS ... High-speed grounding switch 1 ... Bushing 2 ... Transmission line 3 ... Tower 6 ... Grounding container 7 ... Conductor 8 ... Fixed contactor 9 ... Movable contactor 10 ... Puffer arc extinguishing chamber 13 ... Fixed contact Child 14 ... Shield 15 ... Operation rod 16 ... Puffer cylinder 17 ... Moving contact 18 ... Insulation nozzle 19 ... Puffer piston 20 ... Arc 21 ... Coating part

Claims (7)

[Claims] 1. A conductor provided in a grounding container filled with an insulating gas, a fixed contact provided on the conductor, a movable contact provided opposite to the fixed contact, and A puffer cylinder that moves together with the movable contactor and a puffer piston provided inside the puffer cylinder are provided, and a puffer chamber is formed in the space between the puffer piston and the puffer cylinder to open the movable contactor. A high-speed grounding switch that extinguishes the insulating gas in the puffer chamber by the puffer piston by compressing the insulating gas in the puffer chamber to extinguish the arc generated between the fixed contact and the movable contact in the vicinity of the fixed contact. A high-speed grounding switch characterized in that a shield is provided on the surface of the shield, and the surface of the shield is coated with an inorganic insulator. 2. The inorganic insulator is alumina (Al
The high-speed grounding switch according to claim 1, which contains ₂ O ₃ ). 3. The magnesium oxide (M)
The high-speed earthing switch according to claim 1, further comprising gO). 4. The zirconia (Zr) is used as the inorganic insulator.
The high speed earthing switch according to claim 1, further comprising O ₂ ). 5. A conductor provided in a grounded container filled with an insulating gas, a fixed contact provided on the conductor, a movable contact provided opposite to the fixed contact, and A puffer cylinder that moves together with the movable contactor and a puffer piston provided inside the puffer cylinder are provided, and a puffer chamber is formed in the space between the puffer piston and the puffer cylinder to open the movable contactor. A high-speed grounding switch that extinguishes the insulating gas in the puffer chamber by the puffer piston by compressing the insulating gas in the puffer chamber to extinguish the arc generated between the fixed contact and the movable contact in the vicinity of the fixed contact. A high-speed grounding switch characterized in that a shield is provided on the shield, and the surface of the shield is coated with a refractory metal. 6. The high speed earthing switch according to claim 5, wherein the refractory metal is molybdenum (Mo). 7. The high-speed grounding switch according to claim 5, wherein the refractory metal is tungsten (W).