JP2002162423A - Device for current detection of power transmission/ distribution line and for analysis of electrical conditions thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for current detection of power transmission/distribution lines and for analysis of the electrical conditions thereof, capable of accurately detecting a transmission/distribution line current of a phase to be detected by each of sensors disposed in a non-contacting manner at positions for surely keeping a safe distance from the respective power transmission/distribution lines of a three-phase three-wire system, capable of accurately detecting a transmission current of each phase even in multi-channel transmission lines in particular, and capable of monitoring the electrical conditions of the transmission/distribution wireways and their change, such as variations (increases, decreases) in transmission/distribution currents, power interruption work, electrical failures (ground faults, short circuits, etc.). SOLUTION: This device is equipped with the plurality of magnetometric sensors disposed in a non-contacting manner at the respective power transmission/distribution lines of a three- phase three-wire system to each generate a detection output that is a function of current flowing through each line and of the distance to the line, a matrix memory for storing a constant matrix previously set as a function of the distance from each sensor to the line of each phase and of the detection characteristic of each sensor, and a constant matrix multiplication means for computing the currents flowing through the lines of the respective phases, by multiplying a detection output matrix of the sensors with the constant matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a transmission / distribution current flowing through a three-phase three-wire transmission / distribution line or a current at the time of an electrical failure such as a short circuit or a ground fault in a non-contact state with respect to the transmission / distribution line. The present invention relates to a current detection and electrical state analysis device for a transmission and distribution line that can be monitored.

[0002]

2. Description of the Related Art As a sensor for monitoring a current flowing in a transmission / distribution line in a non-contact state, as shown in FIG. 1, a vector sum of induced voltages corresponding to transmission voltages of respective phase transmission lines 21 and 22 is output. The sensor 4 (for example, a coil wound around a rod-shaped core) is fine-adjusted so that each is positioned on the electric center line of the electric wire support (power transmission tower) 1, and its mounting position is determined. There is one that detects a zero-phase current or a short-circuit current (see Japanese Utility Model Laid-Open No. 60-41866).

The above-mentioned electric center line is a position where the strengths of magnetic fields generated by currents flowing through two infinite-length power lines installed in parallel are equal to each other, that is, a normal two-line power transmission system ( In FIG. 1), it means that the distances from the two transmission lines are equal. FIG. 2
As described above, the sensor 4 as described above is arranged at a position as close as possible, away from the transmission and distribution line 2 of each phase by a predetermined safety distance according to each phase voltage, and the current of each phase and An apparatus for detecting a zero-phase current and a short-circuit current is also known (JP-A-9-329639).

[0004]

In the conventional current detecting device, since the sensor is arranged on the electric center line of the wire support, not only fine adjustment of the installation position is required, but also the transmission and distribution of each phase. There is a problem that the current flowing through the electric wire cannot be monitored. In addition, while securing a safe distance, on the other hand, if a sensor is placed as close as possible (or the closest) to detect the current flowing through the transmission and distribution lines of each phase, the current flowing through the wires other than the detection target phase Since it is difficult to remove the influence of the above, there is a problem that the transmission and distribution line current of the target phase cannot be accurately detected. Particularly, in a multi-line transmission and distribution line having three or more transmission and distribution lines, there is a problem in that a malfunction often occurs due to a failure of a line other than the line to be monitored.

The present invention relates to a three-phase three-wire transmission and distribution line,
When sensors are placed in a non-contact state at a position that secures a safe distance from each transmission and distribution line, it is possible to accurately detect the current flowing in the transmission and distribution lines of the phase that each sensor is trying to detect,
In particular, even in a multi-line transmission line, the transmission current of each phase can be accurately detected, and the electrical state of the transmission and distribution line and changes thereof, such as fluctuation (increase or decrease) of the transmission and distribution current, power outage work, and electrical failure (ground failure) It is an object of the present invention to provide a transmission / distribution line current detection and electrical state analysis device capable of monitoring a short circuit, a short circuit, etc.).

[0006]

According to the present invention, there is provided a power transmission and distribution line current detecting device which is arranged near a three-phase three-wire transmission and distribution line in a non-contact state with respect to each of the transmission and distribution lines. A plurality of magnetic field sensors that generate a detection output that is a function of the current flowing through the wire and the distance to each transmission and distribution line, the distance from each of the plurality of sensors to each phase transmission and distribution line, and the detection characteristics of each of the sensors. A matrix memory for storing a constant matrix set in advance as a function; and constant matrix multiplying means for multiplying a detection output matrix of the sensor by the constant matrix to calculate a current flowing through each phase transmission and distribution line. And

Further, the electric state analysis device of the present invention is provided with a current signal of each phase transmission and distribution line output from the constant matrix multiplying means of the transmission and distribution line current detection device, and based on the current signal waveform, Waveform analysis processing means for analyzing the electrical state of the transmission and distribution lines is further provided.
Further, it can be provided with a means for generating a zero-phase current, and a means for generating a subtraction current signal indicating a current change of each phase transmission and distribution line.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a circuit block diagram showing one embodiment in which a magnetic sensor, a filter, and a constant matrix multiplier are applied to a three-phase three-wire transmission line according to the present invention.

[0009] Three-phase currents of a, b, and c phases flow through the three-phase transmission lines 2A, 2B, and 2C, respectively. The three magnetic sensors 4A, 4B, and 4C corresponding to each phase are configured by winding a coil having an appropriate number of turns around the center of a rod-shaped core. For example, as shown in FIG. 2B, 2
It is located at an appropriate position on a steel tower that is separated from C by a distance that can ensure safety. In this case, the position of the magnetic sensor 4 is not critical, and may be slightly shifted up, down, left and right as long as a safe distance is secured.

The detected voltages of the magnetic sensors 4A to 4C are separately input to the corresponding filters 5A to 5C. These filters help remove noise from the detected voltage of the magnetic sensor. The filter output (detected voltage waveform of the magnetic sensor) from which the noise has been removed is used as a constant matrix multiplication unit 8
Supplied to The constant matrix multiplying unit 8 multiplies the output voltages of the filters 5A to 5C by a constant matrix supplied from the constant matrix memory 7 to obtain each phase transmission line 2A.
To 2C are calculated. As described later, the constant matrix stored in the constant matrix memory 7 indicates the relative arrangement (distance between the magnetic sensors 4A to 4C and the transmission lines 2A to 2C) and the characteristics (structure and sensitivity) of each magnetic sensor. It is a constant determined in accordance with it and can be set and stored in advance.

In this case, when the output voltage levels of the filters 5A to 5C deviate from an appropriate range for performing a constant matrix multiplication process, when a gain adjustment is necessary, an appropriate gain signal is output from the gain setting control unit 6. To filters 5A to 5C
And the level of the detection voltage output therefrom is adjusted to a voltage level suitable for the matrix multiplication. When the gain of the filter is adjusted as described above, the constant matrix supplied to the constant matrix multiplier 8 is naturally changed based on the information. The constant matrix will be described later in detail, but the constant matrix in the case of one three-phase three-wire transmission line as shown in FIG. 2 is a 3 × 3 matrix.

In the matrix multiplication process, an A / D converter 9 is arranged between the matrix multiplication unit 8 and the filter 5 as shown by a dotted line in FIG. The analog waveforms of the detected voltages of the magnetic sensors 4A to 4C may be converted into digital signals, and the matrix multiplication may be performed by a digital processing circuit such as a digital processor or a microcomputer.

Next, the operation of the embodiment shown in FIG. 3 will be described. At the time of normal power transmission, each phase wire 2A to 2C of the power transmission line 2 is
Even when a three-phase balanced current flows as shown in FIG. 7, the induced voltages detected by the magnetic sensors 4A to 4C of the respective phases at that time have different magnitudes (amplitudes) for the respective phases as shown in FIG. Often has a waveform. Further, the phase may be slightly shifted depending on the arm length and the arm interval of the power transmission tower 1.

This is because not only the influence of the current flowing through the transmission line of the phase closest to each magnetic sensor but also the effect of the current flowing through the transmission lines of other phases is shown in FIG. To receive it. More specifically, 3
This is because the combined magnetic field of the magnetic field due to the current flowing through each of the phase wires is detected by one magnetic sensor, and furthermore, the distance from each sensor to each phase wire and the relative positional relationship between them are different from each other.

For this reason, although the respective magnetic sensors 4A to 4C are installed corresponding to the respective transmission lines 2A to 2C, the output of the corresponding magnetic sensor accurately represents the transmission current of each phase. It is not possible to do so, and it will interfere with the detection of electrical failures and the determination of failures using the detection voltages of the three magnetic sensors. Therefore, a constant matrix determined based on the relative arrangement of the preset magnetic sensor and each phase transmission line,
Multiply the filtered detection voltage of each magnetic sensor,
After the correction, the current flowing through each phase transmission line is detected as shown in FIG.

The transmission current is detected by such a method based on the following principle. First, as shown in FIG.
When there is only one linear transmission line 2 having an infinite length, the detection voltage V output by the magnetic sensor 4 separated by a distance r from the transmission line 2 is expressed by the following equation 1 according to the well-known Bio-Savart law.

V = k × I / (2πr) Equation 1 where k: magnetic field / voltage conversion coefficient of the magnetic sensor r: distance between the transmission line and the magnetic sensor I: transmission line current.

Therefore, to obtain the transmission line current I from the detected voltage V, the detected voltage V may be multiplied by (2πr / k).

Next, three similar infinitely long power transmission lines 2
In a three-phase power transmission system having A to 2C, a detection voltage Va of the magnetic sensor 4A installed in a relative positional relationship as shown in FIG.

Va = k × Ia / (2π · r1) + k × Ib / (2π · r2) + k × Ic / (2π · r) where Va: detection voltage of the magnetic sensor 4A, r1: magnetic sensor 4A and r2: Distance between magnetic sensor 4A and b-phase transmission line 2B r3: Distance between magnetic sensor 4A and c-phase transmission line 2C Ia: Current of a-phase transmission line 2A Ib: b-phase transmission Current Ic of electric wire 2B: Current of c-phase transmission line 2C. If the current coefficient of the sensor 4A for each transmission line, that is, ki / 2π · ri (where i = 1 to 3) is set to k11, k12, and k13, Equation 2 becomes Equation 3.

Va = k11 × Ia + k12 × Ib + k13 × Ic Equation 3 Since the detection voltages Vb and Vc of the other magnetic sensors 4B and 4C can be considered in the same manner as Va, the respective detection voltages are expressed by the following equations. become that way.

Vb = k21 × Ia + k22 × Ib + k23 × Ic Vc = k31 × Ia + k32 × Ib + k33 × Ic When these equations are displayed in a matrix, Equation 4 shown in FIG. 11 is obtained. In order to obtain Ia, Ib, and Ic from Expression 4, it is necessary to multiply both sides of the same expression by the inverse matrix of the kii matrix of the first term on the right side of Expression 4 and obtain Expression 5 shown in FIG. I understand.

If the inverse matrix of kii of the first term on the right side of Equation 5 is Kii, Equation 5 becomes Equation 6 shown in FIG. As can be seen from Equation 6, the current of each of the three-phase three-wire transmission lines is obtained by multiplying the matrix Vi of the detection voltage of the magnetic sensor by the constant matrix Kii determined by the relative arrangement of the magnetic sensor and the transmission line. Can be.

When the number of lines of the three-phase three-wire transmission line is increased to four, it can be easily understood that Equation 6 becomes Equation 7 (FIG. 14). In this case, since the twelve magnetic sensors equal to the number of transmission lines are arranged corresponding to the transmission lines of each phase, the constant matrix becomes a 12 × 12 matrix. The transmission current can be determined. FIG. 9 shows an outline of a state in which twelve magnetic sensors are installed on the four-line power transmission tower 1.

FIG. 10 is a block diagram showing another embodiment in which the present invention is applied to an electric state analysis of a three-phase one-line transmission line. In this figure, the same reference numerals as those in FIG. 3 represent the same or equivalent parts. A / D converter 9 with filter 5
A to 5C and the constant matrix multiplication unit 8 are arranged, and a stage subsequent to the matrix multiplication unit 8 is constituted by a digital circuit such as a microcomputer. The detected voltages of the magnetic sensors 4A to 4C are input to the filters 5A to 5C corresponding to the respective magnetic sensors and noise is removed, as in the above-described embodiment.

The analog detection voltage signal from which noise has been removed is converted to a digital signal by the A / D converter 9. The constant matrix multiplication unit 8 multiplies the digitized detection signal of the magnetic sensor by the constant matrix supplied from the constant matrix memory 7 and outputs the current signals Ia to Ic flowing through each phase transmission line.
Is obtained. Each phase transmission line current is supplied to the waveform analysis processing unit 1.
3 and also to an adder 10 connected to each output of the matrix multiplier 8. The zero-phase current signal obtained by adding the transmission line current signals for the three phases by the adding unit 10 is further input to the waveform analysis processing unit 13.

Alternatively, or in addition to the zero-phase current signal, a delay unit and a subtraction unit (both not shown) are arranged at the subsequent stage of the adder, and the change of each phase current is calculated based on the change of the zero-phase current. May be calculated and input to the waveform analysis processing unit 13.

In FIG. 10, the transmission currents of the phases a to c are transmitted to the delay units 11 arranged in series at the subsequent stage of the matrix multiplication unit 8.
Is input to the subtraction unit 12 for each phase. In the delay unit 11, the transmission current waveform of each phase is delayed by a predetermined integer cycle, and the delayed current waveform is input to the subtraction unit 12. The subtraction unit 12 at the subsequent stage calculates the difference between each phase current waveform before the delay, which is directly supplied from the matrix multiplication unit 8, and the delay current waveform delayed by the integer cycle as described above, and calculates the change in the transmission current. , Ie, a subtraction current signal is input to the waveform analysis processing unit 13.

Further, in FIG. 10, the voltage sensor 14 is attached to the side of the power transmission tower, and outputs a voltage signal proportional to the transmission voltage. Specifically, the voltage sensor 14
It is composed of a plurality of electrode bodies that generate an induced voltage according to the vector sum of the transmission voltage of each transmission line (Japanese Patent Laid-Open No. 9-329639).
No.). Like the output of the magnetic sensor, the voltage output waveform of the sensor 14 is supplied to the A / D converter 9F after noise is removed by the filter 5F, and is converted into a digital signal.

This digital voltage signal is further supplied to a delay unit 1
1F and subtraction unit 12F, and waveform analysis processing unit 13
Are entered separately. In the subtraction unit 12F, the delay unit 11F
The difference between the sensor output voltage waveform delayed by the above and the output voltage waveform not delayed is calculated to obtain a zero-phase voltage waveform, which is input to the waveform analysis processing unit 13. The fact that a zero-phase voltage is obtained by the delay unit 11F and the subtraction unit 12F is disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 9-329639 filed by the present applicant.

The waveform analysis processing unit 13 has a processing program for analyzing the electrical state of the phase electric wire in advance. This processing program includes the current signal of each phase and the subtraction processing current (the subtraction unit 12 in FIG. 10) obtained as described above.
, Etc.) to perform the following processing.

A. Thresholds and allowable ranges are set in advance for the current of each power line, the subtraction processing current (output of the subtraction unit 12), and / or the zero-sequence current and the zero-sequence voltage. If it exceeds the allowable range, it is determined that an abnormality has occurred in the transmission line, and an abnormality determination / waveform recording for recording the detected current / voltage waveform of each transmission line.

B. Based on the recorded power line current and zero-phase current waveform, the type of failure and the failure phase are determined. The failure type is determined by determining whether each phase power line current (Ia, Ib, Ic) or the power line current subtraction processing current (that is, the current change) is the set short-circuit operation current (minimum current flowing when a short-circuit fault occurs).
If the power line current or the subtraction processing current is less than the short-circuit operating current and the zero-phase current exceeds the set zero-phase operating current (minimum current flowing when a one-line ground fault occurs), Is determined to be a one-line ground fault. Furthermore, the phase in which the power line current or the subtraction processing current exceeds the short-circuit operation current is two or three.
If there is a phase, it is determined as a two-phase short-circuit and a three-phase short-circuit, respectively.

C. When there are a plurality of lines, it is determined which line has a failure based on the occurrence of the failure determined as described above.

D. In the case of a single-line ground fault, by comparing the phases of the recorded zero-phase voltage waveform and zero-phase current waveform, the direction of failure (where the device of the present invention is installed—for example, with respect to the steel tower, (Japanese Unexamined Patent Publication No. 9-329639)
No.). In the case of a short circuit, the failure direction is determined according to whether the phase angle of the power line current or the subtraction processing current is the same or opposite to the preset angle.

E. If the detection output by the voltage sensor decreases,
Based on the change in the power line current, it is determined that the failed line has been interrupted. If there are a plurality of lines, a faulty line can be detected by detecting the interruption (see Japanese Patent Application Laid-Open No. 9-32-9).
No. 9639).

F. The discrimination result obtained in the above processes a to e is converted into digital data or an on / off signal, and related data is transmitted or a relay is operated.

According to the processing program as described above, the increase / decrease monitoring of the transmission current and the zero-phase current of each phase, the detection of line break, the failure type, the failure phase, the failure line, the failure direction and the like when an electrical failure occurs are analyzed. It is identified and the result is output as digital data or ON / OFF data. These data are directly connected to a personal computer or the like (not shown) to the waveform analysis processing unit 13 to display a current waveform or an analysis result, or to transmit a known data transmission device including satellite communication, mobile phone talk, and the like. It can also be transmitted to an electric station or the like, and used for monitoring from a remote location. Further, the device of this embodiment can be incorporated in a fault section detection device or a similar device, and used as data for determining a section or a direction of an electrical fault in a transmission and distribution line.

Generally, when the second embodiment is applied to an n-line transmission line, the sensors 4A to 4C shown in FIG.
Filters 5A to 5C, delay unit 11, and subtraction unit 12
Can be easily understood by those skilled in the art that can be dealt with by increasing n to 3n sets and providing n sets of the adder 10, the voltage sensor 14, the filter 5F, the delay 11F, the subtractor 12F, and the like. There will be.

[0040]

As described above, according to the present invention, there is no need to adjust the mounting of the magnetic sensor, and the effect of improving the efficiency of the mounting operation is expected. Further, according to the present invention, a magnetic sensor is arranged in a non-contact state at a position (a transmission and distribution line support such as a tower) where a safe distance is secured from each of the three-phase three-wire transmission and distribution lines. Since the detected voltages are filtered to remove noise and a constant matrix is calculated for the shaped detected voltages, the phase current flowing in each phase wire to be detected is affected by other phase currents. It can be detected accurately without any problem.

Therefore, accurate zero-phase current and short-circuit current can be detected even in a multi-line transmission line of two or more lines, and the waveform analysis processing can be used to increase or decrease (change) the transmission / distribution current of the transmission / distribution line and to determine the electric current. It is possible to monitor the magnitude of a fault current, a fault type, a fault phase, a fault line, and the like at the time of a mechanical fault. Furthermore, if the transmission / distribution line current detection device of the present invention is incorporated into a conventionally known device such as a fault section detector, processing such as fault section and fault direction determination becomes possible.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of a conventional arrangement of a non-contact sensor for detecting current in a transmission and distribution line.

FIG. 2 is a side view showing another example of a conventional arrangement of a non-contact sensor for current detection of transmission and distribution lines.

FIG. 3 is a circuit block diagram showing one embodiment in which the present invention is applied to a three-phase three-wire transmission line.

FIG. 4 is a conceptual diagram for explaining a principle of detecting transmission / distribution line current by the sensor of the present invention.

FIG. 5 is a conceptual diagram for explaining a principle of detecting each transmission line current when the present invention is applied to a three-phase three-wire transmission line.

FIG. 6 is a waveform diagram showing a normal three-phase balanced current flowing through each transmission line of the three-phase three-wire transmission line.

FIG. 7 is a waveform chart showing an example of each phase voltage waveform detected by each phase sensor of FIG. 3;

8 is a waveform diagram showing an example of a detected voltage waveform of each phase voltage obtained by correcting the waveform of FIG.

FIG. 9 is a side view showing an example of each sensor when the present invention is applied to a three-phase four-line transmission line.

FIG. 10 is a circuit block diagram showing another embodiment in which the present invention is applied to a three-phase one-circuit transmission line.

FIG. 11 is a diagram showing a matrix display of Expression 4.

FIG. 12 is a diagram showing a matrix display of Expression 5.

FIG. 13 is a diagram showing a matrix display of Expression 6.

FIG. 14 is a diagram showing a matrix display of Expression 7.

[Explanation of symbols]

2 ... transmission (distribution) wire, 4, 4A-C ... magnetic sensor, 5
A to C, 5F: filter, 6: gain setting / control unit, 7: constant matrix memory, 8: constant matrix operation unit,
9, 9F: A / D converter, 10: Adder, 11, 1
1F: delay section, 12, 12F: subtraction section, 13: waveform analysis processing section, 14: voltage sensor

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H02H 3/353 G01R 15/02 Z

Claims (8)

[Claims] 1. A three-phase three-wire transmission / distribution line, which is disposed in a non-contact state with respect to each of said transmission / distribution lines, and is a function of a current flowing through each of said transmission / distribution lines and a distance to each of said transmission / distribution lines. A plurality of magnetic field sensors that generate a certain detection output, a distance from each of the plurality of sensors to each phase transmission and distribution line, and a matrix memory that stores a constant matrix preset as a function of the detection characteristics of each of the sensors. And a constant matrix multiplying means for multiplying a detection output matrix of the sensor by the constant matrix to calculate a current flowing through each phase transmission and distribution line. 2. The apparatus according to claim 1, further comprising: gain setting control means for adjusting a detection output of each of the sensors to a value within a level range suitable for multiplying the constant matrix.
2. The current detection device for transmission and distribution lines according to claim 1, wherein when adjusting the detection output of each of the sensors, the constant matrix is also adjusted in accordance with the adjustment. 3. The current detecting device for a transmission / distribution line according to claim 1, further comprising filter means for removing noise included in a detection output of said sensor. 4. The method of adjusting the level of the detection output of each of the sensors,
4. The current detecting device for a transmission / distribution line according to claim 3, wherein the gain is adjusted by adjusting a gain of said filter means. 5. A current signal of each phase transmission and distribution line output from the constant matrix multiplying means of the transmission and distribution line current detecting device according to any one of claims 1 to 4, and based on the current signal waveform, An electric state analysis device for transmission and distribution lines, further comprising a waveform analysis processing unit for analyzing and processing electric states of transmission and distribution lines. 6. An adder for adding current signals of each phase transmission and distribution line output from said constant matrix multiplying means and supplying a zero-phase current signal obtained by said addition to said waveform analysis processing means. The electrical condition analysis apparatus for transmission and distribution lines according to claim 5, characterized in that: 7. A delay section which is supplied with a current signal of each phase transmission and distribution line output from said constant matrix multiplying means, and delays each current signal by a predetermined cycle. 7. An electric state analysis of a transmission and distribution line according to claim 5, further comprising a subtracter for calculating a difference between each of the delayed current signals and supplying the result to the waveform analysis processing means. apparatus. 8. A voltage sensor for detecting a transmission voltage of the three-phase three-wire transmission and distribution line, a second delay unit for delaying the detected voltage signal for a predetermined time, and the delayed voltage signal and the non-delayed voltage signal. 8. The apparatus according to claim 5, further comprising a second subtraction unit for subtracting the detected voltage signal to obtain a zero-phase voltage, wherein the zero-phase voltage is supplied to the waveform analysis processing unit. An electrical condition analyzer for any of the transmission and distribution lines.