JPS60201269A - Detecting method of accident point on power transmission and distribution line by photosensor - Google Patents

Abstract

PURPOSE:To reduce speedily and securely the cost of construction and detect the generation point of a wire breaking accident by providing an optical fiber line which pieces photosensors provided at respective accident detection points successively and sends light to the respective photosensors in series. CONSTITUTION:Light pulse signal transmitters 7 and 8 are controlled by a pulse signal oscillator 6 to send out light pulse signals PA and PB continuously, and photocouplers 9 and 10 send them into the optical fiber line PL. If one wire breaking accident occurs between accident detection point (c) and (d), zero- phase voltage detectors Fd-Fn generate outputs although respective zero-phase voltage detectors Fa-Fc between a power station T to the accident generation point (c) are zero. Therefore, light which passes throgh the zero-phase voltage detectors Fd-Fn from the accident generation point (c) changes in plane of palarization to vary the level of a light pulse signal. Then, level variation detectors 13 and 14 connected to optical receivers 11 and 12 detect the points of time when the level varies and an accident point detector 18 calculates the time difference to detect the accident generation point.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a fault point detection method in a power transmission and distribution system.

In power transmission and distribution systems, it is important to quickly and accurately detect the point of occurrence of an accident and take appropriate measures to recover from a power outage in order to improve services. Therefore, on long power transmission lines, fault point locators, for example, emit pulse waves for locating into the transmission line from electrical stations at both ends, and measure the time it takes for each reflected wave to return from the fault point. A fault point locator is used to measure the distance from the location to the fault point. However, it is often difficult to apply it to power distribution systems, which have a wider area than power transmission lines and have various noise sources.

Therefore, in the distribution system, for example, sectional switches are installed at appropriate distances along the distribution line, and the sectional switches for lines that have lost power (in case of an accident) are sequentially turned on from the substation. A method is used to detect the accident as occurring after the closing section switch that caused the change. However, this method makes it impossible to quickly detect the point of failure, take countermeasures, and recover from a power outage quickly, resulting in a decline in service.

Recently, optical sensors have been used as a non-contact measurement method for measuring voltage and current in high-voltage circuits. an electromagnetic optical effect element (1) such as an effect element; Second condensing lens (
2) (3), the first polarizer, the second polarizer (4), (5), etc.
The inventors of the present invention have proposed a method of detecting an accident point by forming a detection system with a photosensor PS and an optical fiber line PL that transmits and receives light via the optical fiber line PL.

For example, as shown in Fig. 2, this method uses optical sensors PSa, PSb, and PSc installed at appropriate intervals along the track.
....Optical fiber lines PLa, PLb, PLc, which respectively transmit and receive light via PSn, respectively...P
Ln is provided, and the polarization of light passing through the electromagnetic optical effect element (1) (1) as shown by (a,) (b) in the figure changes due to changes in voltage and current depending on the location of the accident.
By carefully changing the level of the optical signal sent through the optical fiber,
The aim is to detect the fault point from the optical signal that causes this level change.

Since this method transmits optical signals through optical fibers, it does not cause incorrect localization due to noise, unlike fault point locators that use electrical pulse waves. The point where an accident occurs can be detected reliably and quickly. However, in this method, it is necessary to provide an optical fiber line and a level detector for each optical sensor. Therefore, the detection system becomes extremely complicated and expensive.
Furthermore, since a large amount of optical fibers are required, an increase in power distribution costs cannot be avoided.

The present invention prevents the amount of electricity indicating a failure from flowing to the electric station, even in the case of a ground fault that can be detected at an electric station, due to the zero-sequence current that flows at the time of a failure, and the point of occurrence of the fault can be detected at the electric station. We provide a method to reliably and quickly detect the occurrence point of disconnection accidents, which often occur in power distribution systems where it is difficult to detect, using optical sensors and optical fiber lines. This allows for prompt countermeasures to be taken to improve services. Next, the details will be explained using the drawings.

The features of the present invention are summarized in the following points. That is, as shown in FIG. 3, each accident detection point a.

Each optical sensor P provided at b, c, d, ... n
Sa+PSb, PSc+PSd+ *・*IIPSn is skewered and an optical fiber line PL is provided in series to each optical sensor without transmitting light, and the ends A→B, as shown by the arrows in the figure.
For example, in the forward and reverse directions from B to A, the first . A second optical pulse signal train PA, PB is transmitted. When a disconnection accident occurs, for example, at point 0 in Figure 3, the polarization plane of the light passing through the optical sensor from detection point C to n will be
The amount of electricity (
For example, the optical pulse train signals PA, P are changed by the zero-sequence voltage) and are sent into the optical fiber line PL from the A and B ends.
Give a change in level to B, and in response to this change in level, A
, detection is performed by utilizing the fact that a time difference t is created based on the accident occurrence position as shown in FIG. That is. Next, a fifth embodiment of the present invention will be described.
This will be explained using figures.

In Fig. 5, PSa, PSb, PSo, PS, --...
. . . PSn is an optical sensor, and the optical sensor shown in FIG. 1, which is made of, for example, a Pockels effect element which causes a change in the plane of polarization of light depending on a voltage, is used.

FEl r Fb r FQ r Fd...Fn indicates a zero-phase voltage detector, and each fault detection point a+ b++ c
. . . n zero-sequence voltage is detected and applied to the electrode of the Pockels effect element. PL is an optical fiber line, and is provided along the line so as to skewer each optical sensor so that light can be transmitted through each optical sensor in series. CP is a signal processing section, and is formed from the following sections. (6)
is an electric pulse signal oscillator, (7) (81 is an optical pulse signal transmitter, (9) 0υ is an optical coupler such as a half mirror, and the optical pulse signal transmitters (7) and (8) are pulse signal oscillators (6). ) is commonly controlled by the output of
) The synchronized first . second optical pulse signal PA,
The optical coupler (9) aα sends out PB continuously, and the optical coupler (9) aα converts it into A.
It is fed into the optical fiber line PL from the end and the B end. 0υ
az is an optical receiver, which receives the optical pulse signal PA' sent from the A end and reaches the B end, and the optical pulse signal PA' sent from the B end and reaches the B end.
The optical pulse signal that has reached the end is converted into electrical signals Pa and Pb. α4 is a level change detector; (149 is a clock pulse oscillator, αHη is a time detector, and ttS is a fault point detector, which operate as follows.

Assuming that no accident occurs now, the zero-phase voltage detectors Fat Fb+ Fc, Fd... installed at each accident detection point.
・The output of F is zero (assuming that the voltages of each phase are balanced among the three phases). Therefore, each optical sensor PSa.

There is no change in the plane of polarization in PSb, ...PSn,
Since the transmitted optical pulse signals PA and PB are not subject to any change in level, the level P is almost the same as the transmission level. and reaches end B and end A as PA' and PB'. As a result, the level change detector (13141 never detects a level change, so the time detector Q7) and the fault point detector αE do not operate, and the fault point detection operation is not performed.

However, for example, as shown in Fig. 3, the installation point C of the optical sensor PS0
If a one-wire disconnection accident occurs between and d, each zero-phase voltage detector Fa,
The outputs of Fb and Fo are zero, but outputs appear in each zero-phase voltage detector Fd+Fe+...Fn after the accident occurrence point C. Therefore, each optical sensor PSa, PSb, PS from the electrical station T to the point where the accident occurred.

There is no change in the plane of polarization of the light passing through d
e, n Produces a change in the plane of polarization of the light. Therefore, the optical fiber line PL
Considering one signal of the optical pulse signal PA sent from the A end of the Since there is no level change due to the sensor, the process proceeds at the transmission level P0.

Then, after passing the accident occurrence point C, a change in level is detected by the optical sensor d-n, and the signal is connected to the B end as PA'.

On the other hand, one pulse signal of the pulse train signal PB sent into the optical fiber line PL from the B end undergoes level changes by each optical sensor from the B end to the accident point C, as shown in FIG. 6(b). Further, between the accident occurrence point C and the electrical station T, the light reaches end A without receiving a level change due to the optical sensor installed at point c-a. The above level changes also occur in the second and subsequent waves of the pulse signal trains PA and PB. That is, when an accident occurs as shown in FIG. 4(C), a − of the optical pulse train 9′ directed toward the A end
Pulses a, b, and c that existed between t and c remain as they are > A
The light pulse d that reached the end and existed between c and d undergoes a level change at the 0 point, d - e .

e-f, f-,,g, ***m l'l-l
. On the other hand, the optical pulse train PA' directed toward the B end has undergone changes since the accident occurred, so it becomes as shown in FIG. 4(d).

Therefore, the levels of the optical pulse signals PA' and Pd that have reached the A and B ends, that is, the output level of the optical receiver Qυα4, are as shown in Figure 4 (a) (bl to (C)) before and after the accident.
d), and the lowest level occurrence point in each receiving number 4 is the track distance 10 from end A to accident point C shown in Figure 5, and from end B to the accident point. This will result in a time difference t based on the difference in line distance 12. Therefore, the level change detector (13Q4) measures the level relative to the level P before the accident, sends out an output when a level difference occurs, and detects the point of level change based on the clock pulse of the oscillator Q9. By detecting with a time detector (10θη) and taking the time difference t at the accident point detector 08, the accident occurrence point C can be determined from this.

Furthermore, when an accident occurs at point d in FIG. 3, the time difference t between the lowest level points becomes longer by the length of the optical sensor, so that it can be detected that the accident point is point d.

Although one embodiment of the present invention has been described above regarding a single wire breakage accident, a double wire breakage accident can also be detected in the same manner. Furthermore, in the above, we have explained the case where optical pulse signals are sent from both ends of a single optical fiber line and transmitted in both directions, but it is important to note that the construction cost due to the optical sensor and optical fiber line will be high. , two optical sensors are provided for each detection point, and two optical fiber lines are provided to skewer the two sets of optical sensor systems, forming a light transmitting and receiving system for transmitting and receiving light in both forward and reverse directions. It can be implemented by Moreover, if it is desired to shorten the distance between detection points, it is sufficient to insert an additional optical sensor and an optical fiber, so it is highly expandable.

As is clear from the above explanation, according to the present invention, the construction cost is much lower than the conventional method using optical sensors and optical fiber lines, and the method can quickly and reliably detect the point of occurrence of a disconnection accident. can be submitted, and its effects are significant when applied to power transmission and distribution lines.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the configuration of the optical sensor, Figure 2 is a diagram showing the conventional method of detecting fault points using the optical sensor, Figures 3 and 4 are
The figure is a circuit diagram for explaining the principle of the present invention and a pulse signal waveform diagram for explaining the operation, and FIGS. 5 and 6 are a circuit diagram and a signal level waveform diagram for explaining the operation of an embodiment of the present invention. (1)... Electromagnetic optical effect element, (2) (3)...
··Condenser lens,. (4) (5)... Polarizer, PSa, PSb, PSo... PSn... Optical sensor, PL... Optical fiber line, L... Distribution line, FFF' ・・・・F ・・・Zero-phase voltage detector,
a+ 1)+ Q n CP...signal processing unit, (6)...electric pulse signal oscillator, ('7)(8)...optical pulse signal transmitter, (9101... Optical coupler, aυoz...
Optical receiver, (+3) Q4)... Level change detector, α9... Clock pulse oscillator, Qlli) (IT)... Time detector, αυ...
...Fault point detector.

Claims (1)

[Claims] An optical sensor consisting of an electromagnetic optical effect element is installed at each fault detection point on the power transmission and distribution line, and an optical fiber line is installed so that each of these optical sensors is skewered, and the optical fiber is connected by the amount of electricity generated on the line at the time of an accident. In addition to causing a change in the polarization plane of the passing light, a bidirectional optical pulse train signal transmitting/receiving system is formed, and the first . A method for detecting a fault point on a power transmission and distribution line using an optical sensor, characterized in that the fault point is detected by utilizing the temporal position of the lowest level change of the second optical pulse train signal at the time of occurrence of the fault being different. ′