JPS6066617A - Flash defect detecting system at transmission line iron tower lightning time - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a transmission line flash accident detection method when a transmission line tower is struck by lightning, and particularly relates to a flash fault detection system that can identify the location of the accident occurrence point on a tower-by- tower basis. Regarding detection method.

(b) Background of the technology In the event of a flash fault caused by a lightning strike, the power transmission is cut off by the fault detection relays at the electric stations at both ends of the power transmission line, but until the power is cut off, the tower of the accident tower receives 50Hz (or 60Hz) and its harmonics. A ground fault current containing wave components flows, and this fault current is detected at the pedestal of the steel tower to determine whether or not a flash fault has occurred.

(C) Conventional technology and problems Conventionally, the flash fault point during a lightning strike was determined by detecting the high-frequency surge component that occurs during a lightning strike using fault locators installed at electrical stations at both ends of the power transmission line, and calculating the distance to the lightning strike point. It is done in this way. In this case, there is a concern that the location accuracy may deteriorate due to changes (attenuation, waveform distortion, etc.) in the high-frequency surge component until it reaches the electrical stations at both ends.

(d) Purpose of the Invention The purpose of the present invention is to reduce the frequency of commercial current waves of 50 Hz that flow through the tower to the ground at a steel tower where a flash fault has occurred due to a lightning strike.
(or 60 Hz) and its harmonic components as input information to determine the location of the accident occurrence point for each tower in order to improve the accuracy of identifying flash fault accidents.

(e) Structure of the Invention The present invention detects whether or not a flash fault accident has occurred in a power transmission line by detecting whether the level of commercial wave current flowing in the tower part of the accident tower and its N duration exceed a reference value. The configuration is such that a determination signal is transmitted to the base.

(f) Embodiments of the Invention An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration, and FIG. 2 is a diagram showing current waveforms at each part. In FIG. 1, 1 is a tower leg of a steel tower, 2 is a current sensor, 3 is a detection device, 4 is a discrimination signal transmitter, and 5 is a transmission line. The detection device 3 includes a bandpass filter 31, a rectifier 32, a level detector 33, and a timer circuit 34. The waveform diagrams (al, (bl, . . ., dl) in FIG. 2 represent waveforms corresponding to the locations (al, peaks), . . . (d) in FIG. 1, respectively.

When lightning strikes, the fault current flowing through the tower pedestal 1 to the ground is picked up by the current sensor 2.

The fault current consists of a commercial wave current of 50 Hz (or 60 Hz) and its harmonics. The voltage booked up by the current sensor 2 is first passed through a bandpass filter 31 (BPF).
The band is limited by 501 (z) and the components from 150 Hz of the third high-fourth wave are passed through to obtain a waveform as shown in Figure 2 (al). It is input as a waveform to the level detector 33.The level loss device 33 detects whether or not the input voltage exceeds a certain reference level. A rectangular wave signal with a time width τ is generated.Here, the reference level is the level at which the power transmission system is judged to be in an accident, and is a value corresponding to the fault current.For a 500 kV power transmission line, 5
A value corresponding to a current of 0 kA is selected. Again, this rectangular wave signal is input to the timer circuit 34, but in the timer circuit 34, if the rectangular wave signal continues for a certain time interval to or more m, it is determined that an accident has occurred, and a judgment pulse force is outputted as shown in the diagram (d). . The time interval to is also determined according to the cutoff time of the power transmission system.
selected according to degree. Next, the judgment pulse of (dl) is changed by the discrimination signal transmitter 4 into a form suitable for the transmission line 5, and is converted into, for example, an on or off signal, and is sent to the transmission destination through the transmission line 5.

In addition, if the transmission means allows it, the level detector 33
It is also effective to count the time width of the rectangular wave signal output, transmit it as a duration value, and perform accident judgment processing at the transmission destination.

(5) As described in detail in the embodiments of the invention, according to the present invention, it is possible to locate the location where flash faults caused by lightning strikes occur on a tower-by-tower basis, and it is also possible to locate transmission distortions such as waveform distortions, unlike conventional methods. Since this method does not use surge components that are susceptible to damage, the accuracy of accident discrimination can be improved, which is highly effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment according to the present invention, and FIG. 2 is a waveform diagram of each part. In the figure, 1 is a tower leg, 2 is a current sensor, 3 is a detection device, 4 is a discrimination signal transmitter, 5 is a transmission line, 31 is a band pass filter, 32 is a rectifier, 33 is a level detector, 34
is a timer circuit.

Claims (1)

[Claims] When a power transmission tower is struck by lightning, a current sensor detects the magnitude of the commercial wave current flowing through the tower, and the current sensor output is input to a timer to detect the duration of the current, thereby preventing flash faults on the power transmission line. A flash fault detection method that detects whether an accident has occurred or not when a transmission line tower is struck by lightning.