JPH04255421A - Protector for distribution line - Google Patents

Abstract

PURPOSE:To prevent breaking of wire by providing a thyristor type fast switch in parallel or in series with a distribution line. CONSTITUTION:In a distribution line protector, a thyristor type fast switch 3 is normally turned OFF. A short circuit fault or a ground fault occurring on a distribution line 2 is detected through a charging current sensor 6 and a controller 10 turns the thyristor type fast switch 3 ON at high speed prior to breaking of the distribution line 2 thus shortcircuiting the distribution line 2 forcibly. Consequently, system voltage on the distribution line 2 drops to extinguish the arc at the fault point thus protecting the distribution line 2 against damage or fusion. According to the invension, service interruption can be prevented reliably from sustaining for a long term.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to a distribution line for preventing the distribution line from being disconnected due to fault current when a short-circuit accident or a ground-fault short-circuit accident that transitions from a ground fault to a short circuit occurs in a distribution line. This relates to a protective device.

0002

[Prior Art] In order to protect the system in the event of a short circuit or ground fault occurring on a power distribution line, circuit breakers and circuit breaker OCRs (overcurrent relays) have traditionally been installed in power distribution substations. is set up. However, the OCR of this circuit breaker has a slow operating characteristic so that it operates after the OCR of the customer circuit breaker operates, so the distribution line may be disconnected due to the arc of fault current while this circuit breaker is operating. There was a problem in that this resulted in long-term power outages.

0003

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems of the conventional art, cuts off the fault current at high speed when a short circuit or ground short circuit occurs on a power distribution line, and prevents disconnection due to arcing of the fault current. It is an object of the present invention to provide a protection device for power distribution lines that can prevent the above.

0004

[Means for Solving the Problems] A first invention made to solve the above problems is a method in which a ground fault fault current or a short circuit fault current flows through a distribution line on the secondary side of a circuit breaker in a substation. It is characterized by the insertion of a thyristor-type high-speed switch in parallel that sometimes operates at high speed to forcibly short-circuit the distribution line. In addition, the second
The invention is characterized in that a thyristor-type high-speed switch is inserted in series in the distribution line on the secondary side of a circuit breaker in a substation to quickly interrupt the distribution line when an earth fault fault current or short circuit fault current flows. That is. Below, these inventions will be explained in more detail with reference to Examples.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the first invention, in which 1 is a circuit breaker installed in a substation, and 2 is a distribution line connected to its secondary side. 3 is a thyristor-type high-speed switch inserted in parallel to the distribution line 2 in or near the substation; it is normally turned off, but when turned on, it prevents the fault current flowing through the distribution line 2. It is now possible to force a short circuit.

FIG. 2 is a more specific circuit diagram, and in addition to showing that a surge protection arrester 4 and a protection switch 12 are connected to the thyristor-type high-speed switch 3,
A system controller 5 for providing a trigger signal to the thyristor fast switch 3 is shown. This system control device 5 constantly takes in the current value of the power distribution line 2 via an optical fiber cable 7 from a photocurrent sensor 6 attached to the power distribution line 2, and converts this into an electrical signal by a light/electrical converter 8. The fault determination circuit 9 then determines whether or not there is a fault current, and when it is determined that there is a fault current, the control device 10 is configured to issue a trigger signal to the thyristor type high speed switch 3 via the thyristor control device 11. There is. Furthermore, if the thyristor-type high-speed switch 3 cannot turn off after a forced short circuit even if the thyristor control device 11 sends an off signal, the control device 10 detects this via the thyristor control device 11 and issues a trigger signal to protect the device. The thyristor-type high-speed switch 3 can be protected by turning off the switch 12.

When installing the configuration shown in FIG. 2 on the distribution line 2, the distribution line 2 is branched as shown in FIG. This can be carried out by connecting the thyristor type high speed switch 3 and the system control device 5 to a thyristor type switching unit 13 installed on the ground through the 12a. 14 in Figure 5
15 is a grounding line, and 15 is a signal line for transmitting a trigger signal to the protective switch 12. The surge protection arrester 4 is connected to the lead wire above the protection switch 12 and grounded. 1
6 is a common grounding line between the surge protection arrester 4 and the protection switch 12. In this embodiment, by turning off the protection switch 12, the thyristor type switching unit 13 can be inspected or repaired without powering off the power distribution line 2.

Furthermore, as shown in FIG. 6, a system unit 17 that houses all of the thyristor-type high-speed switch 3, surge protection arrester 4, system control device 5, photocurrent sensor 6, switching contact 12a, etc. is attached to a utility pole. It can also be installed on top. 18 is a common ground line. In this example, the photocurrent sensor 6 and switching contact 12a are connected to the jumper wire 2a that runs through the system unit 17 to form one unit, so the facility can be made smaller, and since there are no ground facilities, the environment can be beautified. can.

FIG. 3 is a graph showing the starting characteristics of the thyristor type high speed switch 3 according to the present invention. In this graph, the vertical axis represents time and the horizontal axis represents current, and curve A shows the starting characteristics of the thyristor-type high-speed switch 3. Curve B is the OCR activation characteristic of the substation circuit breaker, curve C is the allowable damage characteristic of the electric wire, and curve D is the OC of the customer circuit breaker.
The starting characteristic of R and the curve E indicate the magnetizing inrush current of the transformer. Here, the allowable damage characteristics of electric wires are those with cross-sectional areas of 20 mm2 and 32 mm, which are often used as general distribution lines.
The graph shows arc duration time on the vertical axis and arc current on the horizontal axis for four types of wires of mm2, 60 mm2, and 120 mm2.

As shown in FIG. 3, the starting characteristics of the thyristor-type high-speed switch 3 of the present invention are lower than the OCR of the substation circuit breaker and the allowable damage characteristics of the electric wire, and are lower than the OC of the customer circuit breaker.
It is set in an area higher than R. Therefore, when a short circuit or ground short circuit occurs at any customer on the distribution line, the OCR of the customer circuit breaker is activated first, but the OCR of the customer circuit breaker and the substation is When an accident occurs in a section, the thyristor type high-speed switch 3 is activated to protect the distribution line before the distribution line 2 is disconnected due to an arc.

In the power distribution line protection device of the present invention configured as described above, the thyristor type high speed switch 3 is normally turned off, but as shown in FIG. When a short-circuit accident occurs, the photocurrent sensor 6 detects it, and the control device 10 detects it before the distribution line 2 is disconnected.
turns on the thyristor-type high-speed switch 3 at high speed to forcibly short-circuit the distribution line 2. For this reason, the system voltage of the power distribution line 2 is reduced, and the arc at the fault point is extinguished, so that damage or melting of the power distribution line 2 is prevented. After the arc at the fault point is extinguished and the insulation is restored, the thyristor type high speed switch 3 is turned off again and the system is returned to its original state. These series of operations are automatically completed in a very short time before the OCR of the circuit breaker 1 of the substation is activated.

FIG. 4 shows an embodiment of the second invention, in which a thyristor-type high-speed switch 3 that operates in the same manner as the first invention is inserted in series with the distribution line 2. This thyristor-type high-speed switch 3 is always on, and is turned off only when a fault current is detected to cut off the fault current. The control method and activation characteristics of the thyristor-type high-speed switch 3 are the same as those of the first invention.

In addition, when the thyristor-type high-speed switch 3 is installed in parallel with the distribution line 2 as in the first invention, the conventional time-limited sequential detection of fault points becomes impossible. This timed sequential fault point detection means that when an accident occurs, all the switches on the distribution line 2 are opened, and then they are turned on sequentially starting from the switch closest to the substation, and the switches on the power supply side of the fault section are opened and closed. This is a method of detecting in which section an accident occurred by using the fact that an accident occurs again when the equipment is turned on. However, according to the first invention, if the series of operations of the thyristor-type high-speed switch 3 is completed before the OCR of the substation circuit breaker is operated, this method cannot be used. Therefore, in the case of the first invention, a power distribution automation system is used, and a sensor is installed to detect overcurrent in each switch section, and when an overcurrent occurs, the section where the overcurrent occurs is detected, and the distribution line in that section is Possible methods include a visual inspection method, a method in which an overcurrent detector indicator is placed in each section of the distribution line, and a worker visually detects the accident section, and a combination of these methods. The type of overcurrent detector is not particularly limited, but for example, one that changes color when viewed from below when an overcurrent is detected, or one that opens the insulation cover of an insulator due to overcurrent. can be used.

[0014]

Effects of the Invention As explained above, the present invention provides a thyristor-type high-speed switch in parallel or series with the distribution line, thereby preventing the electric wire from arcing when a ground fault or short-circuit accident occurs. It is possible to quickly cut off the fault current before it melts and prevent wire breakage accidents. Therefore, according to the present invention, long-term power outage accidents can be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the principle of a first invention.

FIG. 2 is a circuit diagram showing an embodiment of the first invention.

FIG. 3 is a graph showing the operating characteristics of the thyristor-type high-speed switch used in the first and second inventions.

FIG. 4 is a circuit diagram showing the principle of the second invention.

FIG. 5 is another embodiment of the first invention, and shows an example of installing poles in a power distribution line.

FIG. 6 is another embodiment of the first invention, and shows another example of installing poles in a power distribution line.

[Explanation of symbols]

1　Substation circuit breaker 2 Power transmission line 3 Thyristor type high speed switch

Claims (3)

[Claims] [Claim 1] In the distribution line on the secondary side of the circuit breaker in the substation,
A power distribution line protection device characterized by inserting in parallel a thyristor-type high-speed switch that operates at high speed and forcibly shorts the distribution line when an earth fault fault current or short circuit fault current flows. [Claim 2] In the distribution line on the secondary side of the circuit breaker in the substation,
A protection device for a power distribution line characterized by inserting in series a thyristor-type high-speed switch that shuts off the distribution line at high speed when a ground fault fault current or short circuit fault current flows. 3. The starting characteristics of the thyristor-type high-speed switch, which are expressed on a graph with time on the vertical axis and current on the horizontal axis, are lower than the OCR of the substation circuit breaker and the allowable damage characteristics of the electric wire. 3. The distribution line protection device according to claim 1, wherein the OCR of the customer circuit breaker is set to be higher than the OCR of the customer circuit breaker.