JP3226554B2 - Locating the accident section of the transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for locating an accident section of a transmission line, and more particularly to a technique for saving labor and speeding up inspection and recovery work of the accident section.

[0002]

2. Description of the Related Art A transmission line of 66 kV to 154 kV class has a large number of branches and a laying length of several tens of kilometers in many cases. Therefore, when a ground fault occurs, labor for searching for the point of the ground fault is required. Will be enormous, and it will take a long time to restore the transmission line.

If there is a transmission line 1 of the neutral grounding type as shown in FIG. 5, the transmission line 1 is divided into a plurality of sections A, B, C, D,.
If it is known that the ground fault point F is one of the sections (section B in FIG. 5), only this section needs to be inspected intensively, so that labor and inspection time can be reduced. Can be planned.

When a grounding accident occurs in the transmission line 1 of the neutral point grounding method, as shown by a broken line in FIG. 6, a neutral point grounding resistance R-transmission line 1-ground fault F-ground G Since the ground fault current i flows through the circuit, the occurrence of the ground fault can be detected by monitoring the zero-phase current due to the imbalance of the three-phase balanced current.

As a method for detecting an increase in the zero-phase current, as shown in FIG. The outputs of the magnetic field sensors 3A and 3B are adjusted so as to cancel each other, and an accident is detected because the output balance is lost at the time of a ground fault, and as shown in FIG.
A magnetic field sensor 3 is installed at the lower part of the tower to monitor an increase in magnetic flux density due to an increase in the zero-phase current, and an electric field sensor 4 is installed at an intermediate portion of the steel tower 2 to change an electric field due to a power transmission stop. A method of preventing a malfunction due to induction noise or the like by adding “?” As an operation condition has been considered.

[0006]

However, all of the above methods have drawbacks in terms of the accuracy of ground fault detection and protection in the event of a lightning strike.

That is, the general transmission line 1 is shown in FIGS.
As shown by, the three lines are arranged vertically, and the respective charging currents become unbalanced based on the difference of the ground capacitance and the like, and even in a normal state, as shown in FIG. Since a small amount of the changing residual current ib flows as a zero-phase current, the magnetic flux density based on the zero-phase current is determined by the magnetic field sensors 3A and 3B
When the detection is to be performed in step 3, it is necessary to consider a threshold value is larger than the maximum value of the fluctuation range of the residual current ib.

In this case, the zero-phase current ip at the time of detection of a ground fault
Is smaller than the threshold is, it is not possible to detect a ground fault, and if a threshold ix smaller than the zero-phase current ip is set, a ground fault can be detected. However, there is a possibility that a ground fault may be detected due to a malfunction even though the transmission line 1 is normal.

In the above two methods, since the magnetic field sensors 3A, 3B, 3 are installed in the middle part of the steel tower 2, etc., it is easy to receive a shock due to a large current at the time of lightning strike.

The present invention has been made in view of the above-mentioned circumstances, and has made it possible to quickly and accurately locate a ground fault with high accuracy.
And it aims at improving the reliability of installation equipment.

[0011]

According to the method for locating an accident section of a transmission line according to the present invention, the method includes the steps of:
Formed by a transmission line with multiple magnetic field sensors arranged
Magnetic field detected by each magnetic field sensor.
Movement within unit time for each of the applied magnetic field strengths
An average value and a standard deviation are respectively obtained , and whether or not the latest value in the strength of each magnetic field is within a range in which each moving average value has a width of a set multiple of each standard deviation . By
This is to locate the section of the transmission line where the accident occurred.

[0012]

[Function] For a plurality of magnetic field sensors arranged near the lower part of the tower
Therefore, each magnetic field of the transmission line detected is, as described above,
Because the transmission lines are arranged vertically,
It fluctuates because the residual current changes every moment. Only
And based on the zero-phase current detected by each magnetic field sensor
Moving average per unit time for each magnetic field strength
Value and standard deviation, respectively, and calculate the maximum of each magnetic field strength.
The new value is calculated by multiplying each moving average by the set multiple of each standard deviation.
Power transmission based on determination of whether or not it is within the range with the width
By locating the section of the track where accidents occur,
Ground faults and the like can be detected quickly and accurately. Special
Of each magnetic field detected by the plurality of magnetic field sensors.
By making the above determination on the strength,
It is possible to detect the occurrence of an accident in a power line.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for locating an accident section of a transmission line according to the present invention will be described below with reference to FIGS.

FIG. 1 is a connection diagram showing an embodiment of a method for locating an accident-occurring section of a transmission line according to the present invention, wherein reference numeral 1 denotes a transmission line, 2 denotes a tower, 3A and 3B denotes a magnetic field sensor, and 5 denotes a magnetic field sensor. An optical fiber composite overhead ground wire, 6 is a detection device, 7 is an optical transmission device, 8 is an optical fiber, 9 is a joint box, 10 is a transmission station, and 11 is a central monitoring device.

When a transmission line of the neutral grounding system is divided into a plurality of sections and these sections are centrally managed, the orientation method is applied to the steel tower 1 as a boundary of the section.

In the vicinity of the lower part of the tower 1, magnetic field sensors 3A and 3B for detecting a magnetic field formed by the zero-phase current of the three-phase transmission line are arranged.

As shown in FIG. 2, for example, two magnetic field sensors 3A and 3B are provided for one steel tower 1 and connected to the detecting device 6.

As shown in FIG. 2, the detecting device 6 includes a surge absorber 61 for protecting the voltage from abnormally rising due to the magnetic field detected by the magnetic field sensors 3A and 3B, and a magnitude of the voltage passing through the surge absorber 61. A / D converter 63 for converting a voltage signal passed through the level adjuster 62 into a digital signal,
A central processing unit (CPU) 64 for processing signals passed through the D converter 63, and a memory for storing various information
65.

The central processing unit 64 includes an A / D converter
Statistical processing is performed based on the time and the detection level of the digital signal transmitted from 63 and changing every moment. That is, a predetermined time of about several seconds is set in advance, a process of calculating a moving average value and a standard deviation that is constantly changing for a detection level within the predetermined time, and a process of calculating the moving average value and the detection level at each time. Is monitored to determine whether or not the difference is within a range having a width of a set multiple of the standard deviation.

Information such as the results of processing and monitoring by the central processing unit 64 is immediately transmitted from the optical transmission device 7 via the optical fiber 8 and the optical fiber composite overhead transmission line 5 to the remote power transmission station 10. To the central monitoring device 11.

The optical transmission device 7 is a multi-drop type optical transmission device shown in FIG.

The central monitoring device 11 includes an optical / electrical signal converter, and performs analysis and determination of received information data, display on a display device, output of an alarm, record display of an accident point, and the like.

Next, the relationship between the change in the zero-phase current (residual current) ib and the ground fault detection will be described with reference to FIG. 4. The moving average value of the zero-phase current i at the set time Δt at time tm is im , The standard deviation is σm, and the moving average value of the zero-phase current i at the set time Δt at time tn is in,
It is assumed that the standard deviation is σn.

Here, the zero-phase current ib at an arbitrary time tm · tn is equal to the standard deviation σm ·
The determination as to whether or not it is within a range having a width of a set multiple (for example, three times) of σn is performed as needed. When a ground fault occurs at time tn, the rapid rise or fall of the zero-phase current ip at the time of the ground fault occurs in a very short time, and the zero-phase current ip is set as shown in FIG. Since the value exceeds the range of the threshold value in ± 3σn, the abnormality can be accurately detected.

In addition, a zero-phase current (residual current) ib in a normal state
Since the value changes slowly, if a moving average value of the magnetic field strength based on the transmission line is calculated and used as a reference, normal fluctuations in the zero-phase current and noise from the surrounding environment when the magnetic field is detected can be used. Malfunction can be prevented from occurring.

[0026]

According to the method for locating an accident occurrence section of a transmission line according to the present invention, a plurality of magnetic field sensors having a magnetic field formed based on a zero-phase current of a transmission line arranged in the vicinity of a lower portion of a steel tower are provided. /> For a predetermined period of time for the strength of each magnetic field.
Calculate the moving average and standard deviation within
The latest value of each magnetic field strength is
Whether it is within the range with the width of the set multiple of the standard deviation
Since the fault occurrence section of the transmission line is determined based on the determination of the above, the following effects are obtained. (1) Even if the zero-phase current changes, the presence or absence of a ground fault is determined based on the moving average value and the standard deviation. The orientation of the section can be performed with high accuracy. I
Of each magnetic field detected by a plurality of magnetic field sensors
The above discrimination based on the moving average value and the standard deviation for the strength
So that only one magnetic field sensor is provided
More accurately than in the case where
Raw can be detected. (2) Since the occurrence of a ground fault is detected when the strength of the magnetic field is out of the range of a multiple of the standard deviation, the fault section is reliably and promptly located. Labor saving and speeding up can be achieved. (3) By arranging a magnetic field sensor or the like near the ground, it is possible to reduce the effect of a lightning strike on a steel tower, improve safety, and facilitate construction and maintenance.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing one embodiment of a method for locating an accident occurrence section of a transmission line according to the present invention.

FIG. 2 is a connection diagram illustrating an example of signal processing of a magnetic field sensor in the iron tower of FIG. 1;

FIG. 3 is a connection diagram showing an example of a multi-drop optical transmission device used for implementing the method for locating an accident occurrence section of a transmission line according to the present invention.

FIG. 4 is a diagram showing a relationship between a temporal change of a zero-phase current and a ground fault detection in the method for locating a fault section of a transmission line according to the present invention.

FIG. 5 is a connection diagram showing a relation between a section of a transmission line of a neutral grounding system and a fault point.

FIG. 6 is a connection diagram illustrating an example of circulation of a ground fault current at the time of a ground fault in a transmission line of a neutral grounding system.

FIG. 7 is a front view of a steel tower showing a conventional example of a ground fault detection method using a magnetic field sensor.

FIG. 8 is a front view of a steel tower showing a conventional example of a ground fault detection method using a magnetic field sensor and an electric field sensor.

FIG. 9 is a diagram showing a relationship between a temporal change of a zero-phase current and a threshold value at the time of a transmission line ground fault.

[Explanation of symbols]

 F Ground fault R Neutral ground resistance G Earth 1 Transmission line 2 Steel tower 3A / 3B Magnetic field sensor 5 Optical fiber composite overhead ground wire 6 Detector 7 Optical transmission device 8 Optical fiber 9 Joint box 10 Power transmission station 11 Central monitoring device 61 Surge absorber 62 Level adjuster 63 A / D converter (CPU) 64 Central processing unit 65 Memory

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-90073 (JP, A) JP-A-2-78972 (JP, A) JP-A-54-94373 (JP, A) JP-A-2-943 52234 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/08 G01R 31/02 G01R 19/00 H02H 7/26 H02H 3/26-3/30 H02H 3/32 -3/52

Claims (1)

(57) [Claims] A plurality of magnetic field sensors are arranged near a lower part of a tower.
To detect the magnetic field formed by the transmission line
And the strength of each magnetic field detected by each magnetic field sensor
For the moving average and the standard deviation within the unit time
Respectively obtained, the latest value of the intensity of each magnetic field respectively
A method for locating an accident-occurring section of a transmission line, comprising locating an accident-occurring section of a transmission line according to whether or not the moving average value is within a range of a set multiple of each standard deviation. .