JPH01138474A - Discriminating device for accident section - Google Patents

Abstract

PURPOSE:To discriminate an accident section immediately by converting light outputs of magnetic field sensors into electric signals, finding the zero-phase current of a power cable from the electric signals, and comparing the phase of the zero-phase current and then discriminating the accident section. CONSTITUTION:Magnetic fields produced with currents of electric conductors of respective three phases U-W of the power cable 2 are detected by the magnetic field sensors 3U1-3W1, and 3U2-3W2 arranged at different positions of the cable 2, and their light outputs are supplied to an accident section discrimination part 7 as the electric signals through optical fibers 4 and 5 and a photoelectric conversion part 6. For example, if a ground fault accident X1 occurs to the W phase in the section 2a of the cable 2, an accident current flows as shown by a solid-line arrow. Then, the sensors 3W1 and 3W2 among the sensors 3U1-3W1 and 3U2-3W2 detect larger accident currents than other sensors 3U1, 3V1, 3U2 and 3V2. The light outputs are converted by the conversion part 6 photoelectrically and supplied to the discrimination part 7. Consequently, the discrimination part 7 detects the zero-phase current any more and discriminates the accident.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an accident section discriminating device for determining the section where an accident has occurred when an accident such as a ground fault occurs in a power system.

[Conventional technology]

In a power system, when a ground fault occurs in a power cable, it is necessary to discover the fault location without delay and make efforts to restore the fault as soon as possible. However, the power cables in the power system are extremely long (installed over a wide range of locations, making it difficult to find the point of a fault. Therefore, power cables are divided into predetermined lengths, and section switches, for example, are installed at each section. When an accident occurs in a power cable, an accident investigation worker goes to the site, opens a sectional switch, separates the power cable, and conducts a trial transmission, or conducts a mega test to first detect the accident. The fault point is discovered by discovering the section and then inspecting the section.In addition to this, recently, when an accident occurs, the sectional switch detects the fault current and automatically opens the circuit. Otherwise, in the event of a power outage due to an accident, power is forcibly transmitted from the substation to close the sectional switches in the healthy section one after another, and the sectional switches in the accident section are disconnected from the normal section. When the circuit is closed, the fault current causes the substation's feeder circuit breaker to operate to cut off the power again, and the feeder circuit breaker maintains the cutoff state.

[Problem that the invention seeks to solve]

As mentioned above, when a ground fault occurs in a power cable in a power system, the point of the fault is the accident investigation worker's opening of a sectional switch, or the automatic opening or automatic shutoff of a sectional switch or feeder circuit breaker. The system is separated from the healthy section by operation, but in either case, an accident investigation worker must perform an inspection to find the accident section, which takes time and causes a problem of prolonging the power outage.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an accident section determination device that can determine the accident section of an accident that has occurred in an electric power system and can centrally monitor the accident section at one location.

[Failure to solve the problem]

The accident zone determination device according to the present invention includes a plurality of magnetic field sensors that optically detect magnetic fields generated in the wires of each phase of a power cable, a photoelectric conversion unit that converts the optical output of each of the magnetic field sensors into an electrical signal, an accident area determination unit that determines the zero-sequence current of the power cable based on the electrical signal of the photoelectric conversion unit and determines the accident area by comparing the phases of the determined zero-sequence current; and a signal that outputs the output of the accident area determination unit. The present invention is characterized by comprising a signal sending section for sending out signals to a transmission path.

[Effect]

A magnetic field sensor detects the current in the wires of each phase at different locations on the power cable. The optical output of the magnetic field sensor is converted into an electrical signal by a photoelectric conversion section, and is provided to an accident zone determination section. The accident zone determination unit determines the zero-sequence current and compares the current phases detected by the respective magnetic field sensors. When the current phases are in the same phase, the accident section determining section determines that the accident section is the section on one side spanning the ceramic field sensor, and when the current phases are opposite, it determines that the accident section is the section on the other side spanning the ceramic field sensor. The determined judgment data is sent to the signal transmission path by the signal sending section.

This allows you to confirm the accident zone at the same time as the accident occurs.
.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a schematic diagram of an accident section discriminating device according to the present invention applied to an electric power system. Power is supplied via a three-phase transformer 1 to a three-phase power cable 2 connected to the loop. Note that an appropriate load (not shown) is connected to this power cable 2. Since the power cable 2 has a long length, it is extended by connecting it at an appropriate position, and a magnetic field sensor 30 is installed at the connecting position to optically detect the current of each of the three phases U, V, and W at that position. ．． , 3Vl, 3WI, and 3U2°3V2, 3Wz are respectively located outside the capacitor 2 and fixedly disposed close to the electric wires of each phase.

This magnetic field sensor detects the strength of a magnetic field by utilizing the Faraday effect, a phenomenon in which the plane of polarization of light rotates depending on the strength of the magnetic field.For example, a heavy flint glass ( SF6 glass) crystal is used.

Magnetic field sensor 3U+, 3V+, 3W+ and 3Uz, 3Vz
, 3Wz are optically connected to one end of optical fibers 4 and 5 consisting of a light emitting optical fiber and a light receiving optical fiber, respectively, and the other end is optically connected to the photoelectric conversion unit 6.
That is, the other end of the light emitting optical fiber of the optical fiber 4.5 is connected to a light emitting section in the photoelectric conversion section 6, and the other end of the light receiving optical fiber is connected to a light receiving section in the photoelectric conversion section 6. This results in
The light traveling through each light emitting optical fiber is sent to a magnetic field sensor 3UI,
3V1.3W, and 3Llz, 3Vz.

The light enters a polarizer (not shown) within 3h and is linearly polarized.

The linearly polarized wave enters a Faraday element (not shown),
When it receives a magnetic field in the direction of the optical axis while passing through it, the plane of polarization rotates and travels. The traveling light enters an analyzer (not shown), and the intensity of the light emitted from the analyzer changes in relation to the strength of the magnetic field, that is, the magnitude of the current, so that the current can be detected optically. It has become.

The photoelectric conversion unit 6 includes each magnetic field sensor 3Ur, 3V+, 3L
The light of 3 Uz, 3 Vz, and 3 Wz is received by the light receiving section and photoelectrically converted, and an electrical signal related to the photoelectrically converted current is given to the accident zone determining section 7.

The accident section determination unit 8 includes both magnetic field sensors 3U+ and 3V+.
.

311, 3uz, 3vz, .
z is equipped with a phase comparator that compares the phases of the detected phase currents. If the zero-sequence current is not detected, the fault section determining section 8 determines that, for example, a ground fault has occurred in the power cable 2.

Also, by phase comparison, both magnetic field sensors 3UI, 3vI, 3W
If it is detected that the current phases of I, 3Uz, 31h, and 3Wz are in the same phase, the fault point is the magnetic field sensor 30.
+, 3V +.

It is determined that the power cable 2 is located on one side of the power cable 2 spanning 3WI, 3Uz, 3Vz, and 3W2, that is, the section 2a. If it is detected that the phase is opposite, it is determined that the fault point is on the other side of the power cable 2, that is, in the section 2b. Then, signals indicating these accident data and section determination data are given to a signal sending section 8, which is a slave station of a communication device connected to the signal transmission line.

The signal sending unit 8 is configured to send the signal given to the accident section determining unit 7 to a signal transmission line (LAN), not shown, to which a master station of the communication device is connected.

Next, the operation of this accident area discriminating device for determining an accident area will be explained with reference to FIG. 3 phases each phase U of power cable 2,
The magnetic field generated by the current in the V and W wires is the power cable 2.
Magnetic field sensors 3U+, 3V+, 3W+ and 3Uz, 3Vz, which are installed at different positions (power cable connection part)
3Wz, and provide their respective optical outputs to the photoelectric conversion unit 6 via optical fibers 4 and 5.

The photoelectric converter 6 photoelectrically converts each of the applied optical outputs and provides these electrical signals to the accident zone determination section 7 . The accident zone determination unit 7 includes magnetic field sensors 3UI and 3Vl.

The respective zero-sequence currents are determined based on the phase currents detected by 3WI, 3LIz, 3Vz, and 3L, but if no ground fault has occurred in the power cable 2, zero-sequence current is obtained, so no fault is determined. Therefore, the accident section determining section 7 does not output a signal of determination data and does not determine the accident section of the power cable 2.

When, for example, a ground fault X occurs in the W phase of the section 2a of the power cable 2, the fault current flows in the direction indicated by the solid arrow. and a magnetic field sensor 3u.

Among the 3V, 3Wl and 3Uz, 31h, 3Wz, the magnetic field sensor 3-036 detects a fault current larger than the current detected by the other magnetic field sensors 3U+, 3V+ and 3Uz, 3v. The optical output is photoelectrically converted by the photoelectric conversion section 6 and is given to the accident section determination section 7. As a result, the accident section determination unit 7 no longer detects the zero-sequence current and determines an accident.

Also, both magnetic field sensors 3U+, 3V+, 3Wt and 3Uz,
31h.

36 compares the phases of the detected currents. In the case of the ground fault X1, the fault current flows as shown by the solid line, so the magnetic field sensors 3W+ and 3-2 detect currents in the same phase. Therefore, the accident section determination unit 7 determines that the accident occurred on the power cable 2.
It is determined that the interval 2a is the interval 2a.

Then, the signals of the accident determination data and the section determination data are given to the signal transmitter 8, and the signal transmitter 8 transmits them to the signal transmission line (LAN) to which the master station is connected.

Separately, when a ground fault occurs in the W phase of the section 2b of the power cable 2, the fault current flows in the direction indicated by the broken line arrow. And magnetic field sensor 3W.

3vz is another magnetic field sensor 3U1.3'V, and 3Uz,
Detects a fault current that is larger than the current detected by 3Vz.

Therefore, as described above, the fault section determination diagram 7 no longer detects the zero-sequence current and determines a fault. Also, since the fault current flows as shown by the dashed arrow, the magnetic flux sensors 3W+ and 3
6 detects currents having opposite phases to each other.

Therefore, the accident section determination unit 7 determines that the accident occurred on the power cable 2.
It is determined that the area is in section 2b, and the signal sending unit 8 sends out signals of the accident judgment data and the section judgment data to the signal transmission path.

In this way, if an accident occurs in the power cable 2, the accident can be immediately confirmed and the accident section can be determined. Therefore, after an accident occurs, the point of the accident can be immediately identified and recovery from the accident can be started, and the power outage time can be significantly shortened.

In this embodiment, magnetic field protectors 3U+, 3V+, 3W+ and 3Uz, 3Vz are installed at two different positions on the power cable 2.
, 3L are provided, but it goes without saying that magnetic field sensors may be provided at two or more positions. Also power cable 2
It goes without saying that the accident section can be determined in the same way even if the lines are not connected in a loop.

Furthermore, accidents are not limited to ground fault accidents.

〔Effect of the invention〕

According to the present invention, when an accident occurs in the power system, the accident section can be immediately determined.

Therefore, an excellent effect can be achieved, such as being able to quickly deal with an accident that occurs in a power cable, and greatly shortening the time required for a power outage due to an accident.

[Brief explanation of the drawing]

FIG. 1 is a schematic % formula of the accident zone discrimination device according to the present invention. Magnetic field sensor 4.5 Optical fiber 6.
...Photoelectric conversion section 7... Accident section determination section 8...
Signal sending section

Claims (1)

[Claims] 1. A plurality of magnetic field sensors that optically detect the magnetic field generated in the wires of each phase of the power cable, a photoelectric conversion unit that converts the optical output of each of the magnetic field sensors into an electrical signal, and an electrical signal of the photoelectric conversion unit an accident area determination unit that determines the zero-sequence current of the power cable and compares the phases of the determined zero-sequence current to determine an accident area; and a signal for sending the output of the accident area determination unit to a signal transmission path. An accident section discriminating device comprising: a sending section.