JP2003161755A - Power transmission line sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noncontact power transmission line sensor which is hardly influenced by an output due to a power transmission line of another phase, the weather or the like, whose adjustment accompanying the installation of the sensor can be reduced and whose mounting workability is satisfactory. <P>SOLUTION: The power transmission line sensor is provided with a sensor in which a voltage sensor and a current sensor are integrated, thereby, it is made to be attached easily to a power transmission line steel tower. The line sensor is provided with a correction circuit, and it can obtain an automatically corrected signal value. Consequently, a large accuracy is not required when the sensor is attached, the mounting operation of the line sensor can be shortened, and a burden on an operator can be reduced. By limiting the arrangement and installation position of the sensor in advance to a definite range, the sensor can be arranged and installed easily in a position in which an influence due to other lines is small, and a more precise signal value can be obtained. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line sensor which is provided on a transmission line tower and can be used in a fault monitoring system for an overhead transmission line, a system for locating a fault section or a fault point, and the like. More specifically, the present invention relates to a power transmission line sensor that is not easily affected by output due to another phase of the power transmission line, weather, etc., and that the sensor can be easily installed.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 63-51274 is known as a fault point locating system for detecting a fault caused by a break in a power transmission line, a lightning strike, or the like, and for specifying the position of the fault. . Further, as a fault locating system capable of accurately identifying a fault position even if there is a branch or a long distance, a sensor for detecting a surge caused by a fault is provided in a transmission line tower, and the method is disclosed in Japanese Patent Laid-Open No. 2000-
Japanese Patent No. 152501 is proposed.

A sensor provided on such a transmission line tower is
Contact type sensors that directly connect to power transmission lines such as current transformers (CT, ZCT, etc.), instrument transformers (PD, PT, etc.), etc., as well as non-contact type sensors that detect electric fields, magnetic fields, etc. Can be mentioned. Of these,
The sensor that can be installed and removed without directly touching the power transmission line and is easy to install is a non-contact type sensor.

[0004]

However, a normal transmission line tower is provided with a plurality of lines. For example, in a square tower with two lines installed side by side, each phase is arranged vertically due to the mechanical strength of the tower, and each line is evenly provided on the left and right,
The tracks are installed so that each line is parallel. Therefore, when a non-contact type sensor for detecting an electric field and a magnetic field is provided on a steel tower and used, it may be affected by an electric field and a magnetic field generated by different phases and lines. Also,
A non-contact sensor that measures the potential difference between a power transmission line and the ground by the partial pressure between the air space capacity and a predetermined capacity of a capacitor is unstable because the air space capacity depends on the weather. There's a problem.

Further, in the installation work of the non-contact type sensor, in addition to correction for the above problem, it is necessary to finely adjust the distance from the measured line and the angle so that the imbalance of the signal value of each sensor does not appear. In addition, since the installation location is high, the work efficiency is poor and the burden on the operator is large. For this reason, there is a demand for a sensor that does not require fine adjustment work and that is easy to install.

The present invention solves the above-mentioned problems, and is less susceptible to the output due to the power transmission line of another phase, weather, etc., and can reduce the adjustment accompanying the sensor installation. An object of the present invention is to provide a sensor for a power transmission line.

[0007]

A sensor for a power transmission line of the present invention includes a current sensor 21 for non-contact detection of an energization current for one phase of a three-phase AC power transmission line, and the one-phase component of the power transmission line. A non-contact voltage sensor 22 for detecting the voltage of each of the three lines, and three sensor units 2 provided on each phase line of the power transmission line,
The zero-phase current obtained by combining the current signals output from the current sensor 21 of each sensor unit and the zero-phase voltage obtained by combining the voltage signals output from the voltage sensor 22 of each sensor unit are normal. The present invention is characterized by including a correction circuit unit 3 that corrects the value of each current signal and each voltage signal so that the value becomes zero or within a set value range during power transmission.

Further, the power transmission line is provided with two lines, each of the sensor parts has a line of each phase as an apex, and two lines selected from other two phases or lines of each phase of another line to the apex. Can be provided on the side surface of the power transmission line steel tower on the side of the measurement power transmission line that is surrounded by two straight lines that pass through and that is substantially located on a straight line that bisects the acute angle side of the two straight lines. Further, the current sensor 21 is a magnetic sensor using a coil with a core, and the directivity of the coil is provided at a position substantially perpendicular to the power line of the measured phase of the power transmission line. The voltage sensor 22 may include a capacitor that is configured by a conductive plate 221 facing the power line and insulated from a ground portion and a conductive container. Further, the correction circuit unit may further include surge detection means for performing surge detection based on at least one of the voltage signal, the current signal, the zero-phase voltage, and the zero-phase current.

The "current sensor" may be arbitrarily selected as long as it can measure the absolute value or the relative value of the current flowing through the power transmission line in a non-contact manner. An example of this is the use of a magnetic sensor that measures the magnetism that occurs with energization. Further, as the magnetic sensor, in addition to the method using the coil described in claim 2, a sensor using a Hall element or a magnetoresistive element can be exemplified. Further, the "voltage sensor" may be arbitrarily selected as long as it can measure the absolute value or the relative value of the potential applied to the power transmission line in a non-contact manner. Examples of this include a vibrating capacitance type as recited in claim 2 and a pyroelectric type. The above-mentioned "surge" refers to a pulse generated when a transmission line such as a disconnection or a lightning strike breaks down. The above-mentioned "substantially positioned" means that it is not necessary to dispose them so as to be positioned exactly on a straight line. Specifically, within 50 cm square (preferably 3 cm) from the corresponding point of the steel tower located on the straight line.
It can be within 0 cm square, more preferably within 20 cm square).

The "correction circuit section" can be provided with any output means. As the output means, display means for displaying numbers or the like, wired output means for appropriately amplifying and outputting with an electric wire or optical fiber, and a wireless device such as a dedicated wireless device, a mobile phone, a PHS phone and a wireless LAN device are used. For example, a wireless output means for transmitting the information can be exemplified. Further, a GPS receiver can be provided in the correction circuit unit to correct the reference time. Further, the position information of the GPS receiver can be added to the output by the wired output means and the wireless output means. By performing the output including the position information, the receiving side can easily identify the information transmitted from the plurality of power transmission line sensors and can easily reconstruct the power transmission line network information and the like.

The sensor section and the correction circuit section may be integrated, or they may be connected separately by wire or wirelessly. By separately providing the sensor unit and the correction circuit unit, only the sensor unit can be provided on the power transmission line side and the correction circuit unit can be provided at any position on the steel tower, so that workability can be improved.

[0012]

According to the power transmission line sensor of the present invention, the voltage sensor and the current sensor are integrated to facilitate the attachment to the power transmission line tower. Further, by providing the correction circuit unit, it is possible to obtain the signal value that has been automatically corrected by the correction circuit unit without performing fine position adjustment and signal value correction. For this reason, it is possible to perform a simple mounting work without requiring great accuracy in mounting the sensor unit, and it is possible to shorten the mounting work of the power transmission line sensor and reduce the burden on the worker. it can. Further, since the correction circuit unit automatically corrects the change in the signal value due to the change in the weather, temperature, etc., the correct signal value can always be obtained.

Further, by limiting the arrangement position of the sensor unit to a certain range in advance, it becomes easy to arrange the sensor unit at a position where the influence of other lines is small, and a more accurate signal value can be obtained. it can. Furthermore, by providing a current sensor and a voltage sensor in one container and forming the container as a part of the voltage sensor, it is possible to obtain a sensor unit with less internal structure and easy installation workability. Further, by providing the power transmission line sensor with the surge detection means necessary for determining the power transmission line failure and its position, the failure point locating system can be easily constructed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the power transmission line sensor of the present invention will be described in detail below with reference to FIGS. As shown in FIG. 3, the power transmission line sensor is provided in the power transmission line tower 4, and is a sensor for detecting the energizing current and voltage in order to check for a failure or the like of the overhead line. 1. Configuration of Transmission Line Sensor The transmission line sensor 1 includes a current sensor 21 as shown in FIG.
And a sensor circuit 2 including a voltage sensor 22, and a correction circuit unit 3 that corrects the outputs of the sensors 21 and 22 and wirelessly transmits them. Further, one sensor unit 2 is provided for each phase of the three-phase AC transmission line.

(1) Sensor unit 2 As shown in FIG. 3, the sensor units 2 (2a, 2b, 2c) provided in the respective phases (a), (b), (c) of the transmission line are magnetically permeable composites. A current sensor 21 and a voltage sensor 22 are provided in a container 201 made of stainless steel or aluminum having a resin lid 203. In addition, the current sensor 21 includes a coil 211 on the core 211.
2 is a wound magnetic sensor. Further, the core 211 is composed of an air core or the like in addition to a magnetic material using ferrite, silicon steel plate or the like. The current sensor 21 is provided such that the side peripheral surface of the core 211 faces the power transmission line.

The voltage sensor 22 includes a container bottom surface 202 and a metal conductive flat plate 2 arranged in parallel with the container bottom surface 202.
It is an oscillating capacitance type voltmeter with a capacitor constituted by 21. Further, a fixed capacitor 222 is provided in parallel with this capacitor.

The container 201 and the lid 203 are screwed so as to keep a hermetically sealed state with an airtight means (not shown) such as a packing, an O-ring and a sealant sandwiched therebetween. Moreover, as shown in FIGS. 4 and 5, the steel tower 4 is provided in the container 201.
A fixed frame 204 used for mounting the fixed frame is attached. This fixed frame 204 is a frame 205 assembled in a rectangular shape.
And the insertion plate 2 provided so as to traverse the frame 205.
06 and a fixing plate 207 for fixing the container 201 to the frame 205 at a predetermined angle.

The container 201 is installed in the steel tower 4 using the fixed frame 204 as described below. The insertion plate 206 is inserted between the intersecting positions of the structure plates 41 that intersect so as to cross the steel tower, and the intersecting position and the inserted insert plate 206
Screw so that it penetrates. In addition, the structure plate 41 and the frame 2
The structural plate 41 and the frame 20 are also provided at four points where 05 intersect.
Screw so that it penetrates 5. The order of screwing these is not particularly limited. In addition, the container 201 is fixed to the fixed frame 2 in advance.
The installation work may be performed in a state in which the container 201 is fixed to the tower 04, and the container 201 is fixed to the fixed frame 20 after the fixed frame 204 is fixed to the steel tower 4.
It may be fixed at 4.

(2) Correction Circuit Section 3 The correction circuit section 3 comprises a correction means 31 and an output means 32. The correction means 31 includes the sensor units 2a for the respective phases (a), (b) and (c),
It is a means for performing correction so that the zero-phase current and zero-phase voltage, which can be obtained by respectively combining the output values of the current sensor 21 and the output value of the voltage sensor 22 obtained from 2b and 2c, become zero. In this correction, a correction value F used for correction is created so that the zero-phase current and zero-phase voltage obtained by combining at a predetermined time become zero.

The output means 32 is means for outputting the output value of the current sensor 21 and the output value of the voltage sensor 22 corrected by the correcting means 31. Further, the output means 32 encodes each output value and wirelessly transmits it to the outside via a PHS telephone at a predetermined interval or when the output value satisfies a predetermined condition. The output means 32 is not limited to the wireless transmission by the PHS telephone, but is a display means for displaying numbers or the like.
Wired output means that appropriately amplifies and outputs using an electric wire or optical fiber, and wireless output means that transmits using a wireless device such as a dedicated wireless device, a mobile phone, and a wireless LAN device can be used.

The power source of the power transmission line sensor is not particularly limited and can be arbitrarily selected. Examples of this include a battery charged by a solar cell, a wind power generator, or the like, induction power from a power transmission line, or the like.

2. Arrangement of Sensor for Power Transmission Line The position where the sensor 1 for power transmission line is arranged will be described in more detail. As shown in FIG. 3, the mounting position of the sensor unit 2 of the power transmission line sensor 1 is on the side surface of the steel tower 4 on the straight line L that is not easily affected by other phases and lines. Further, although the position of the correction circuit unit 3 is in the lower portion of the steel tower 4 in FIG. 3, the position is not limited to this, and it can be set at any place.

The straight line L is the sensor portion 2c for measuring the phase (c).
In Fig. 3, the two straight lines La 'and Lb' connecting the phases (a ') and (b') of the other line and the phase to be measured (c) are straight lines that bisect the acute angle side.
On this straight line, the distances are approximately the same as those of the phases (a ′) and (b ′), and the electric fields and magnetic fields generated from the phases (a ′) and (b ′) cancel each other out to reduce the influence. Therefore, phase (a '),
Since it is less affected by (b '), it is possible to reduce correction and obtain more accurate current signal value and voltage signal value.

The position where the sensor portion 2c is arranged is a straight line L connecting the phases (b ') and (c') of another line and the phase to be measured (c).
It is also possible to set it on a straight line L'that bisects the acute side of b ', Lc'. At this position, the influence of the phases (b ') and (c') can be reduced. Further, the straight lines Lb and La ′ connecting the phases (b) and (a ′) and the phase to be measured (c) may be bisected on the acute angle side.

Further, the position where the sensor portion 2c is provided does not have to be exactly on the straight lines L, L ', etc., and the deviation may be within 50 cm square. This is because there is a distance of several meters from the phase (c) of the power transmission line to the sensor unit 2c, and this degree of deviation is not greatly affected by other phases and can be eliminated by correction by the correction circuit unit 3. . The other sensor units 2a and 2b are also arranged in the same manner as the sensor unit 2c described above.

3. Correction Processing of Signals A method of correction processing of current signals and voltage signals obtained from the current sensor 21 and the voltage sensor 22 of each phase will be described. The current signal and the voltage signal output by the current sensor 21 and the voltage sensor 22 included in the power transmission line sensor 1 are used as a zero-phase current signal and a zero-phase voltage signal by vector-synthesizing the signals of the respective phases. . The zero-phase current signal and the zero-phase voltage signal are usually zero when there is no failure. However, it becomes a value other than zero due to a shift in the positional relationship between the sensor unit 2 and the power transmission line, a change in conditions due to a change in atmosphere such as a change in weather, and the like.

Therefore, the transmission line sensor 1 corrects each signal by the correction means 31 of the correction circuit unit 3 so that the zero-phase current signal and the zero-phase voltage signal at the time of no failure become zero. Make signals easier to use. As a method of this correction processing, (1) batch correction of the same amount for all three phases,
(2) It is possible to select two types of individual correction for some or all phases according to the state of each phase. Since the same method can be used to correct both zero-phase current and zero-phase voltage, the description is common.

(1) Collective correction method This correction method is a method of performing correction by adding a common correction value to the signal value of each phase. In the present method, when the composite value of each phase appears as S in a steady state when no failure occurs as shown in FIG. 6, as shown in FIG. 7, the correction value obtained by halving the scalar of S is obtained. In this method, F is calculated, and the correction value F is vector-calculated and subtracted from each signal value to perform the correction. By performing this correction, the zero-phase current signal and the zero-phase voltage signal at the time of non-fault become substantially zero, which makes it easy to distinguish from the non-zero at the time of fault.

(2) Individual correction method In this correction method, it is checked whether the signal value of each phase is within the allowable range. If the signal value is outside the allowable range, the correction is performed by the combination of phases outside the allowable range. This is a method of determining the phase to be performed and correcting only the relevant phase. Table 1 below shows a combination table for determining this correction phase.

This table shows whether the signal values of the other two phases are within the permissible range when the signal value of a certain phase is zero, which is represented by "O" and "X". For example, phase (a) is 0
If the signal value is zero, the other (b) and (c) phases may be within the allowable range if they are approximately sin2 / 3 times the maximum value and approximately sin4 / 3 times the maximum value. it can. In this case, the phase (a) can be determined to be correct if it is within the allowable range even when the other two phases are examined. However, as a result of examining other phases, if the phase is outside the allowable range, it is determined that the phase (a) does not show a correct signal value.

[0031]

[Table 1]

A. As shown in Example 8 of Table 1, when the signal values of all the phases are within the allowable range, they are output as they are without correction. B. As shown in Examples 1 to 3, when the signal values of two phases are out of the allowable range at the same time, it is considered that the signal values of only the remaining one phase have changed. The same level of signal correction as that of the two phases is performed so that the combined value of the three phases becomes zero. For example, as shown in Example 1, only the case of examining (a) phase is within the allowable range, and other (b),
If the (c) phase is outside the allowable range, consider that the (a) phase signal value is abnormal and correct the (a) phase signal value.
The combined value of the three phases should be zero. Further, as the correction value F of the signal value of the (a) phase, the scalar of the three-phase vector composite value, which is the same as in “(1) Batch correction method”, is used.

C. As shown in Example 4, when all the three phases are out of the allowable range, the signal values of all the phases are corrected. The correction at this time is the same as “(1) Batch correction method”. D. As shown in Examples 5 to 7, when the signal value of only one phase is out of the allowable range, it is considered that the correct determination has not been made for the other two phases. Therefore, the signal value of each phase is acquired again to make the determination. Need to do.

In the individual correction method as described above, the zero-phase current signal and the zero-phase voltage signal at the time of non-fault become substantially zero as in the case of "(1) Batch correction method", and it is easy to distinguish from the non-zero at the time of failure. Become. Further, by correcting only the signal value that is considered to be abnormal using the combination table, a more accurate signal value can be used.

(3) Timing of correction processing, etc. The correction value F used in each of the above-described correction processing is not always obtained, but the one obtained at an arbitrary timing is used. This timing includes an acquisition command from the outside (such as a button provided on the sensor for the power transmission line, a command by the communication means, and the like) and a combination thereof when the power of the power transmission line sensor 1 is turned on at predetermined intervals. It can be illustrated. Even if the correction value is determined in this way, since the surge current and the surge voltage that occur at the time of failure are changes that occur in a short period of time, there is no effect on the combined value S used for correction, and even if this correction is performed. It can be easily detected as a change in the zero-phase current signal and the zero-phase voltage signal. Incidentally, in order to avoid correction with an abnormal signal value such as noise, it is possible to use an average value of several correction values F. Further, the correction value F is not limited to the above "one third", and another size can be used.

3. Effect of Transmission Line Sensor According to the present transmission line sensor, the current sensor 21
Also, by preparing the sensor unit 2 in which the voltage sensor 22 is integrated, the attachment to the power transmission line tower 4 is facilitated. Further, by providing the correction circuit unit 3, it is possible to obtain a signal value that has been automatically corrected by the correction circuit unit 3 without performing fine position adjustment and signal value correction. For this reason, the sensor unit 2 is not required to be attached with high accuracy, and the attachment work can be performed easily. The attachment work of the power transmission line sensor is shortened and the burden on the operator is reduced. You can Further, since the correction circuit unit 3 automatically corrects the change of the signal value due to the change of the weather, the temperature, etc., the correct signal value can always be obtained.

Further, by limiting the arrangement position of the sensor unit 2 to a predetermined range such as on the straight line L, it becomes easy to dispose the sensor unit 2 at a position where the influence of other lines is small and more accurate. It is possible to obtain various signal values. Furthermore,
Current sensor 21 and voltage sensor 22 in one container 201
By including the container 201 as a part of the voltage sensor 22, it is possible to provide the sensor unit 2 which has less internal structure and is easy to install.

4. Sensor for power transmission line provided with surge detection means Further, as shown in FIG. 8, the sensor for power transmission line is provided with surge detection means in addition to the sensor unit 2 and the correction circuit unit 3,
It can be used as a transmission line sensor capable of detecting a surge.
A power transmission line sensor equipped with this surge detecting means is shown in FIG.
As shown in, the surge detector 33 is provided in the correction circuit unit 3.

The surge detecting means 33 vector-synthesizes the output value of the current sensor 21 and the output value of the voltage sensor 22 corrected by the correcting means 31 into a zero-phase current and a zero-phase voltage, respectively. When the voltage becomes non-zero, it is detected as a surge. Alternatively, when the output value of the current sensor 21 corrected by the correction unit 31 is out of the predetermined setting range, within a predetermined time from that time,
It is determined whether or not the output value of the voltage sensor 22 corrected by the correction means 31 falls below a predetermined value, and if it falls, it is detected as a surge. When a surge is detected by these methods, the output means 32 is used to output that the surge has been detected.

The transmission line sensor equipped with such a surge detecting means can easily locate the failure point by providing the transmission line sensor 1 with the surge detecting means necessary for determining the failure of the transmission line and its position. The system can be built.

In addition, as shown in FIG.
PS receiving means 34 can be provided. The GPS receiving unit 34 is a unit that receives GPS radio waves, obtains current time information included in the GPS radio waves, and obtains the position of the correction circuit unit 4. Further, the current time information and the obtained position information are provided to the correction means 31 and the output means 32. Further, the correction means 31 determines the time to create the correction value F based on the current time information. Further, the output means 32 collectively outputs the signal values and the position information from the correction means 31 and the surge detection means 33 to the outside by wireless or wire.

Such a power line sensor can be synchronized with a power line sensor of another line or a power line sensor of another steel tower from accurate current time information. In addition, by adding position information to various signal values, the receiving side of various signal values can easily identify the information transmitted from a plurality of transmission line sensors and easily reconstruct the transmission line network information and the like. be able to. The power transmission line sensor can be used as a sensor for a monitoring device, a fault section locating device, a fault point locating device, or the like by further including any means. Further, at least one of the sensor unit and the correction circuit unit can be integrally provided in each device.

The present invention is not limited to the above-mentioned embodiments, but various modifications may be made within the scope of the present invention according to the purpose and application. That is, in the present transmission line sensor, the three sensor units and the correction circuit unit are separate bodies, but the correction circuit unit can be integrated with any one of the sensor units. In such a power transmission line sensor, the number of wires and the number of installation works are reduced, and the workability can be further improved. Further, the correction circuit unit may be divided and provided in each sensor unit, or a correction circuit capable of handling the sensor units of a plurality of lines may be provided.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining a configuration of a power transmission line sensor.

FIG. 2 is a schematic diagram for explaining a configuration inside a sensor unit of a power transmission line sensor.

FIG. 3 is a schematic diagram for explaining a state in which a power transmission line sensor is provided on a power transmission line tower.

FIG. 4 is a schematic enlarged view for explaining a state in which a power transmission line sensor is provided on a power transmission line tower.

FIG. 5 is a schematic enlarged view for explaining a state in which a sensor portion of a power transmission line sensor is provided on a power transmission line tower.

FIG. 6 is a schematic diagram for explaining how signals of respective phases are combined when the correction circuit unit does not perform correction.
It should be noted that signal synthesis is vector synthesis, and this diagram is simply represented.

FIG. 7 is a schematic diagram for explaining how signals of respective phases are combined when correction is performed by the correction circuit unit. It should be noted that signal synthesis is vector synthesis, and this diagram is simply represented.

FIG. 8 is a block diagram for explaining a configuration of a power transmission line sensor including surge detection means.

FIG. 9 is a block diagram for explaining the configuration of a power transmission line sensor including surge detection means and GPS reception means.

[Explanation of symbols]

1; power line sensor; 2, 2a, 2b, 2c; sensor part, 201; container, 202; container bottom part, 203; lid, 2
04; fixed frame, 205; frame, 206; insertion plate, 207;
Fixed plate, 21; current sensor, 211; core, 212; coil, 22; voltage sensor, 221; conductive flat plate, 22
2; fixed capacitor, 3; correction circuit section, 31; correction means, 32; output means, 33; surge detection means, 34; G
PS receiving means, 4; steel tower, 41; structural plate.

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Claims (4)

[Claims] 1. A current sensor 21 for non-contactly detecting an energization current for one phase of a three-phase AC transmission line, and a voltage sensor 22 for non-contactly detecting a voltage for the one phase of the transmission line. However, a zero-phase current obtained by synthesizing the three sensor units 2 respectively provided on the respective phase lines of the power transmission line, the current signals output from the current sensors 21 of the respective sensor units, and the respective sensor units. The correction circuit unit 3 that corrects the values of the current signals and the voltage signals so that the zero-phase voltage obtained by combining the voltage signals output from the voltage sensor 22 is zero or within the set value range during normal power transmission. A sensor for a power transmission line, comprising: 2. The transmission line is provided with two lines, and each of the sensor sections has a line of each phase as an apex, and two lines selected from other two phases or lines of each phase of another line to the apex. The transmission line according to claim 1, which is provided on a side surface of a transmission line steel tower on the side of a measurement transmission line that is surrounded by two straight lines that respectively pass through and that is substantially located on a straight line L that bisects an acute angle side of the two straight lines. Sensor. 3. The current sensor 21 is a magnetic sensor using a coil with a core, and the direction of the directivity of the coil is substantially perpendicular to the power line of the phase to be measured of the power transmission line. The transmission line sensor according to claim 1 or 2, wherein the voltage sensor 22 includes a capacitor configured by a conductive plate 221 facing the power line and insulated from a ground portion and a conductive container. 4. The correction circuit unit further comprises surge detection means for performing surge detection based on at least one of the voltage signal, the current signal, the zero-phase voltage and the zero-phase current. 3. The power transmission line sensor according to any one of 3 above.