JPH03199903A - Apparatus for detecting looseness of transmission line - Google Patents

Abstract

PURPOSE:To correctly monitor the looseness of a power line at all times by receiving the result of detection by each sensor at a potential part of the earth and obtaining the distance between the lowest point of the lowest phase of the power line and the surface of the ground. CONSTITUTION:A looseness sensor 3 hung in the vicinity of a supporting point 11 of a transmission line 1 of the lowest phase forms a stray capacitance C1 between a sensor casing 31 and the surface 5 of the ground. Similarly, a looseness sensor 4 hung at the lowest point 12 forms a stray capacitance C2 between the casing 31 and the surface 5. Charging current measuring circuits 32 in the sensors 3, 4 measure the stray capacitances C1, C2 in the form of charging currents I1, I2, respectively. The currents I1, I2 measured by the circuits 32 are sent to a looseness operating device 6 as a radio signal via a radio antenna 34 by a radio transmitter 33. The device 6 obtains the distance between the lowest point 12 of the transmission line 1 of the lowest phase and the surface 5 of the ground with use of the result of detection of stray capacitances to the ground which is fed from the sensors 3, 4, thereby presuming the looseness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power transmission line sag detection device for monitoring the sag of a power transmission line.

[Prior Art] Power transmission lines are indispensable equipment necessary for today's power transmission line operations, and accidents or failures of this equipment have an extremely serious impact on today's highly electrified society, and in some cases can cause damage in all directions. social functions may be paralyzed. Therefore,
It is extremely important to constantly maintain power transmission lines in a healthy condition.

One of the important items in the maintenance of power transmission lines is the management of sag in the power lines. The sag of power transmission lines constantly changes depending on the current flowing through the transmission line, ambient temperature, solar radiation, wind, etc., and an extreme increase in sag leads to a decrease in the separation distance from objects. , there is a risk of causing serious accidents such as flashover accidents. For this reason, in the past, maintenance personnel were required to go to the site and perform measurements at a distance using surveying instruments, insulating rods, etc., in addition to management based on sag calculations.

[Problem to be solved by the invention] However, with the above-mentioned conventional technology, it is difficult to accurately grasp the actual situation of the power transmission line at all times, and it requires a large amount of manpower. There was a strong desire to develop sensing technology that could perform constant measurements.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power transmission line sag detection device that eliminates the drawbacks of the prior art described above and is capable of constantly and accurately monitoring the sag of a power transmission line.

[Means for Solving the Problems] The power transmission line sag detection device of the present invention detects ground floating capacitance at the lowest point of the lowest phase power transmission line and near the tower support point in an overhead power transmission line supported by a steel tower. A sensor equipped with a detection means and a transmission means for transmitting the detection result to the earth potential section is installed, and the earth potential section receives the detection result from each sensor, and the ground potential section receives the detection result from each sensor, and transmits the detection result using the ground stray capacitance detection result of both. This system is equipped with calculation means for determining the distance between the lowest point of the lowest phase of the wire and the ground surface and estimating the sag.

There are two types of above-mentioned stray capacitance detection means as follows.

The first method is to measure the voltage between the case and the power transmission line using the case of the sensor as an electrode, and the capacitance formed between the case and the power transmission line, and the series circuit of the capacitance formed between the case and the ground. This circuit evaluates the ground stray capacitance of the case. The second method is to measure the stray capacitance to the ground formed between the case and the ground using the case of the sensor as an electrode, and measure the charging current that flows into the stray capacitance from the power transmission line. This is a charging current measurement circuit that evaluates stray capacitance.

Transmission between the sensor and the calculation means may be wired or wireless. In the case of a wired method, it is preferable to install an optical fiber between the sensor and the calculation means, and to transmit the detection results of each sensor through the optical fiber. In the case of wireless, the transmitting means of the sensor is a wireless transmitter that transmits the detection result of the sensor to the calculating means by a wireless signal.

Preferably, the sensor includes a power supply circuit that extracts operating power from a current flowing through the power transmission line or a magnetic field created around the power line.

[Function] The power transmission line sag detection device of the present invention has sensors installed at two locations on the lowest phase wire of the power transmission line, at the lowest point of sag and near the support point on the tower, and when each sensor This method evaluates the sag of power transmission lines based on the measured floating capacitance to the ground.

The stray capacitance between the transmission line and the ground near the tower support point is constant, but the stray capacitance between the transmission line and the ground at the lowest point changes depending on the sag of the transmission line, and each It is detected by the ground stray capacitance detection means provided in the sensor. This detection result is transmitted from the transmitting means of each sensor to the calculating means in the earth potential section by wire or wirelessly.

The calculation means uses the received ground stray capacitance detection results from both sensors to determine the distance between the lowest point of the lowest phase of the power transmission line and the ground surface, and estimates the sag. Therefore, the slackness of the power transmission line can be accurately monitored at all times.

Specifically, to detect the stray capacitance between the electrode and the ground,
A method of detecting the partial voltage between the power transmission line and the electrode by using the sensor case as an electrode and using the capacitance partial pressure formed between the power transmission line, the electrode, and the earth, and the charging current that flows into the stray capacitance between the electrode and the earth. There is a method of detecting this by connecting a current measuring means between the electrodes of the power transmission line.

As a method for transmitting measurement results from a sensor installed on an electric wire to a ground potential section, since the power transmission line is charged to a high voltage, transmission using an optical fiber is preferable.

Furthermore, if the sensor has a built-in power supply circuit that derives from the current flowing through the power transmission line 1 itself, maintenance such as battery replacement becomes unnecessary.

[Example] Hereinafter, the specific contents of the present invention will be explained in detail by way of actual examples.

FIG. 1 is a principle diagram illustrating the operation of the power transmission line sag sensor of the present invention. Among the power transmission lines supported by the steel tower 2 in which insulator chains are inserted, the lowest-phase power transmission line 1 has a transmission line with the configuration shown in FIG. A wire slackness sensor 3 is attached. Further, a power transmission line slack sensor 4 having the same configuration is also attached to the lowest point 12 of the lowest phase electric wire 1, that is, the so-called deep bottom.

FIG. 2 shows the specific configuration of the power transmission line sag sensors 3 and 4, which have a sensor case 31 suspended from the power transmission line 1. Inside this sensor case 31, the sensor case 31 and the A low impedance charging current measuring circuit 32 is connected between the electric wire 1 and the electric wire 1 . This charging current measuring circuit 32
1 measures the charging current I flowing into the ground stray capacitance C between the sensor case 31 and the ground surface 5, and indirectly works as a ground stray capacitance detection means. This is because, assuming that the voltage to the ground of the power transmission line 1 is V, the charging current I flowing into this floating capacitance C to the ground is given by the following equation.

I=jωCXV (1) Furthermore, a wireless transmitter 33 is installed inside the sensor case 31, and transmits the value of the charging current I measured by the charging current measuring circuit 32 by a wireless signal. Sensor case 31
The radio antenna 34 extends from the inside to the outside and transmits the signal to a long distance. The power source for each of these circuits 32 and 33 inside the sensor case 31 is derived from the current flowing through the power transmission line 1 by a through-type current transformer 35 attached to the power transmission line 1 and a power supply circuit 36 provided inside the sensor case 31.
To be precise, it is derived from the magnetic field created by the current around the wire. Therefore, maintenance such as battery replacement is unnecessary.

Returning to FIG. 1, the power transmission line sag sensor 3 suspended near the support point 11 of the lowest phase power transmission line 1 forms a stray capacitance C1 between the sensor case 31 and the ground surface 5. Similarly, the power transmission line sag sensor 4 suspended at the lowest point 12 forms a stray capacitance C2 between the sensor case 31 and the ground surface 5. The charging current measurement circuit 32 in the power transmission line slackness sensors 3 and 4 measures these stray capacitances C1 and C2 using their charging current II.

Measured in the form of I2.

The charging current 11 measured by the power transmission line slack sensor 3 near the support point 11 is expressed by the following equation.

II = Jωci xv (2)
Similarly, the charging current I2 measured by the power transmission line slack sensor 4 at the lowest point 12 is expressed by the following equation.

I2 = JωC2XV (3) Charging current 11 measured by these current measuring circuits 32
．． I2 is sent as a radio signal from the radio antenna 34 by the radio transmitter 33 to the sag calculation unit [6].

The sag calculation device 6 uses the ground stray capacitance detection results sent from both power transmission line sag sensors 3 and 4 to determine the distance between the lowest point 12 on the lowest phase power transmission line 1 and the ground surface 5. Find the distance and perform calculations to estimate the sag.

In this embodiment, the ground stray capacitance C1 of the power transmission line slack sensor 3 at the support point 11 is known and constant, and
First, the other ground stray capacitance C2 is specified based on the received charging current values 11 and 12, and by multiplying the result by a predetermined function, the distance between the lowest point 12 on the transmission line 1 and the ground surface 5 is determined. , and estimate the sag d of the power transmission line 1.

That is, the sag calculation device 6 first calculates the above equations (2) and (3).
V is deleted from the equation, and the ground stray capacitance C2 of the power transmission line sag sensor 4 at the lowest point 12 is calculated using the following equation.

C2=C1xI2/II (4)
Here, since the stray capacitance C1 to the ground is constant, if 11 and 2 can be measured, the stray capacitance C2 to the ground can be calculated.

Next, the actual ground clearance at the lowest point 12 of the power transmission line 1,
The correspondence relationship with the ground stray capacitance C2 of the sensor case 31 at that time can be determined in advance by calculation or experiment, and the sag d of the power transmission line 1 at that time is expressed by a function. Therefore, the sag calculating device 6 calculates the sag d of the power transmission line 1 by substituting the above-described calculated stray capacitance to the ground C2 into this predetermined function.

Now, the sag d of the power transmission line 1 increases, and the distance between the lowest point 12 of the lowest phase of the power transmission line and the earth surface 5 becomes shorter 1, and the distance between the transmission line sag sensor 4 at the lowest point 12 and the earth surface 5 decreases. Stray capacitance C
2 increases by the capacity corresponding to the shortened distance, and becomes C2'. Therefore, the charging current transmitted to the sag calculation device 6
The value of 2 also increases. The sag calculating device 6 calculates the actual ground clearance at the lowest point 12 of the power transmission line 1 based on the value of the floating capacitance C2° determined from the above equation (4), and calculates the current height of the power transmission line 1. Find the value of sag d and calculate the current sag d
judge whether it is appropriate or not.

In this manner, the sag calculation device 6 can evaluate whether the sag d of the power transmission line 1 is appropriate by monitoring the value of the ground stray capacitance C2.

In the power transmission line sag sensor shown in FIG. 2, a current measuring circuit 32 is provided as a ground stray capacitance detection means, but by using the sensor case 31 as an electrode, A series circuit is configured between the capacitance between the sensor case 31 and the capacitance (stray capacitance) formed between the sensor case 31 and the ground surface 5.
A voltage measurement circuit for measuring the voltage between the power transmission line 1 and the sensor case 31, that is, the divided voltage of the series circuit described above, is provided in the sensor case 1, and thereby the stray capacitance of the sensor case 31 to the ground can be evaluated.

In the above-described practical example of the power transmission line sag detection device, the measurement result of the charging current is transmitted to the sag calculation device 6 wirelessly, but it is also possible to optically transmit it by wire instead of wireless transmission.

For example, an optical fiber is laid between the power transmission line sag sensor 3 and the sag calculation device 6, and an electric/optical signal converter is provided as a wired transmitter in the sensor case 31, and the charging current measurement circuit 32 outputs an optical fiber. can be converted into an optical signal by an electrical/optical signal converter and transmitted to the sag calculation device 6 on the ground via the optical fiber.

In addition, the results obtained by the sag calculation device 6 are applied to the steel tower 2.
Fiber-optic transmission can also be carried out to remote monitoring points through optical fibers built into optical fiber composite overhead ground wires (oPGW).

[Effects of the Invention] As explained above, according to the power transmission line sag detection device 3 of the present invention, the sag of the power transmission line is directly detected.
It becomes possible to constantly and accurately monitor the slackness of power transmission lines.

[Brief explanation of drawings]

FIG. 1 is a principle diagram illustrating the operation of the power transmission line sag detection device of the present invention, and FIG. 2 is a configuration diagram showing an embodiment of the sensor of the power transmission line sag detection device of the present invention. In the figure, 1 is the lowest phase transmission line, 2 is the steel tower, 34 is the transmission line sag sensor, 5 is the ground surface, 6 is the sag calculation device, 11 is the vicinity of the support point of the transmission line, and 12 is the transmission line sag sensor. The lowest point, 31 is a sensor case, 32 is a charging current measurement circuit, 33 is a wireless transmitter, 34 is a wireless antenna, 35 is a through-type current transformer, 36
indicates the power supply circuit.

Claims (1)

[Scope of Claims] 1. Ground stray capacitance detection means and the detection results are transmitted to the ground potential section at the lowest point of the lowest phase power transmission line and near the tower support point in the overhead power transmission line supported by the steel tower, respectively. A sensor equipped with a transmitting means is installed, and the detection results from each sensor are received at the ground potential part, and the detection results of both ground stray capacitances are used to determine the lowest point of the lowest phase of the transmission line and the ground surface. A power transmission line sag detection device, characterized in that it is provided with a calculation means for determining the distance to the sag and estimating the sag. 2. The above ground stray capacitance detection means uses the case of the sensor as an electrode to detect a series circuit of capacitance formed between the case and the power transmission line, and a capacitance formed between the case and the ground. 2. The power transmission line sag detection device according to claim 1, wherein the circuit measures the voltage between the two and evaluates the ground stray capacitance of the case. 3. The ground stray capacitance detection means uses the case of the sensor as an electrode to measure the charging current flowing into the ground stray capacitance formed between the case and the ground from the power transmission line, and detects the ground based on the current value. 2. The power transmission line sag detection device according to claim 1, wherein the power transmission line sag detection device is a charging current measuring circuit that evaluates a ground stray capacitance between the case and the ground. 4. Transmission line sag detection according to claim 1, 2 or 3, characterized in that an optical fiber is laid between the sensor and the calculation means, and the detection results of each of the sensors are transmitted through the optical fiber. Device. 5. The power transmission line sag detection device according to claim 1, 2 or 3, wherein the transmitting means of the sensor is a wireless transmitter that transmits the detection result of the sensor to the calculating means by a wireless signal. 6. The power transmission line sag according to claim 1, 2, 3, 4, or 5, wherein the sensor includes a power supply circuit that extracts operating power from a magnetic field created around the wire by a current flowing through the power transmission line. Detection device.