JP3839093B2 - Method for locating acicular wave generation point in distribution line - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention detects a needle-like wave zero-phase current and zero-phase voltage generated by a fine ground fault (also called an intermittent ground fault) that occurs as a precursor of a complete ground fault in a distribution line, and generates a needle-like wave generation point. It is related with the method of locating.
[0002]
[Prior art]
Provided at both ends of the transmission line to be located the failure point is a surge receiver that receives a surge caused by the failure that occurred in the transmission line, and the position of the failure point of the transmission line by the difference in the reception time of the surge at both ends In the fault location device for locating the error, a fault location device that calibrates the difference in the reception time of the surge by the time signal of the standard radio wave JJY or NHK is disclosed in Japanese Patent Laid-Open Nos. 56-63274 and 63-51274. It is known.
[0003]
Further, before the insulation of the three-phase distribution line 1 as shown in FIG. 5 deteriorates and reaches a complete ground fault in which the fundamental current flows, a needle-like waveform called a so-called micro ground fault with almost no fundamental wave component is formed. The zero-phase current I ₀ and the zero-phase voltage V ₀ may occur as a complete ground fault precursor phenomenon.
[0004]
As shown in FIG. 5, sensors 2 and 3 for detecting acicular waves are provided on the distribution line 1 at intervals, and the detection signals of the acicular waves are transmitted to the slave stations 6 and 7 by cables 4 and 5, respectively. A system is known in which the slave stations 6 and 7 transmit the received detection signals to the master station 9 via the communication line 8 as information of an appropriate signal form.
[0005]
In this known system, the master station 9 is provided in a substation provided with a transformer for supplying power to the distribution line 1 and the sensors 2 and 3 are built in the section switch. Is transmitted to the respective section switches via the communication line 8, the slave stations 6 and 7, and the cables 4 and 5, and is utilized as a distribution line automation system for operating these section switches.
[0006]
[Problems to be solved by the invention]
In the distribution line 1 of FIG. 5, when a needle-like wave as a fine ground fault occurs at the point E, if the distance L ₁ from the point E to the sensor 2 or the distance L ₂ from the point E to the sensor 3 can be known. It is extremely effective for maintenance of distribution lines.
[0007]
For this purpose, if the time of the internal clock or counter built in the slave stations 6 and 7 is calibrated with an accurate time signal, the slave stations 6 and 7 receive the needle wave detection signals from the sensors 2 and 3, respectively. It is considered that the distance L ₁ or L ₂ can be determined based on the difference in time.
[0008]
In the figure, e ₁ and e ₂ are propagation times when the needle-like waves generated at the minute ground fault point E reach the sensors 2 and 3, respectively, h ₀ is the needle-wave detection delay time of the sensors 2 and 3, and c ₁ Is the time for the needle-shaped wave detection signal from the sensor 2 to be transmitted to the slave station 6 by the cable 4, and c ₂ is the time for the needle-shaped wave detection signal from the sensor 3 to be transmitted to the slave station 7 by the cable 5.
[0009]
Now, if the internal clocks of the slave stations 6 and 7 are accurately set by some method, the sensors 2 and 3 detect the needle-like waves generated at the point E, and the slave stations 6 and 7 detect the detected signals. Assuming that the time until reception is E ₁ and E ₂ , respectively, from the reference time of the internal clock,
In the slave station 6, E ₁ = e ₁ + h ₀ + c ₁ (1)
In the slave station 7, E ₂ = e ₂ + h ₀ + c ₂ (2)
Values E ₁ and E ₂ are obtained, so that data of these values E ₁ and E ₂ is transmitted to the master station 9 via the communication line 8 and the difference E ₁ −E ₂ is calculated.
E ₁ −E ₂ = (e ₁ −e ₂ ) + (c ₁ −c ₂ ) (3)
It becomes.
[0010]
When e ₁ + e ₂ is added to the right side of equation (3) and halved,
(1/2) · {(e ₁ −e ₂ ) + (c ₁ −c ₂ ) + (e ₁ + e ₂ )}
= E ₁ + (1/2) · (c ₁ −c ₂ ) (4)
It becomes.
[0011]
If c ₁ = c ₂ , the propagation time e ₁ can be obtained by the equation (4). Therefore, the distance from the point E to the sensor 2 is multiplied by the propagation velocity Ve of the needle wave surge on the distribution line 1. L ₁ can be obtained by the following equation (5).
[0012]
L ₁ = e ₁ · Ve (5)
Although it seems as if the needle wave generation point E can be determined in this way, this method has the following three problems.
[0013]
The first problem is that it is practically difficult to set the internal clocks of the slave stations 6 and 7 accurately.
The second problem is that the length of the communication line, that is, the distance between the slave stations 6 and 7 must be known.
[0014]
The third problem is that the lengths of the cables 4 and 5 must be equal, or the lengths of the cables 4 and 5 must be known correctly in advance.
For the first problem, the master station 9 repeats the time reference signal A at a constant time interval (cycle) and sends it to the slave stations 6 and 7 via the communication line 8. A method of calibrating the internal clocks of the slave stations 6 and 7 each time they are received by the slave stations 6 and 7 can be considered.
[0015]
However, in this method, the internal clock of the slave station 7 is always delayed by the time a ₂ when the time reference signal A propagates from the position of the slave station 6 to the position of the slave station 7 on the communication line 8. , the following equation (6) time E ₂ 'is obtained in place of the time E ₂ represented by the foregoing equation (2).
[0016]
E ₂ '= e ₂ + h ₀ + c ₂ -a ₂ (6)
Thus in order to obtain a time E _2, it is necessary to correct only propagation time a ₂ (6) time E ₂ 'obtained by the formula.
[0017]
For this purpose, the propagation time a ₂ must be known, but in order to know the propagation time a ₂ , the distance between the slave stations 6 and 7 (strictly, the length of the communication line 8 between both slave stations) is measured, Although the distance is obtained on a map, there is a trouble that the work is required every time the position of the slave station is changed (second problem).
[0018]
The same applies to the lengths of the cables 4 and 5 between each sensor 2 or 3 and the corresponding slave station 6 or 7, respectively. In the case of changing the installation, a great deal of trouble is required. (Third problem).
[0019]
The above method for sending the time reference signal A through the communication line 8 is summarized as follows. However, t ₃ is the time from when the time reference signal A passes through the slave station 6 until the needle wave is generated at the point E, that is, the time from the reference time of the slave station 6 until the needle wave is generated. (See FIG. 2).
[0020]
E ₁ '= t ₃ + e ₁ + h ₀ + c ₁ (7)
E ₂ ′ = t ₃ + e ₂ + h ₀ + c ₂ −a ₂ (8)
_{(1/2) · (E 1 '} -E 2' + e 1 + e 2)
= E ₁ + (1/2). (C ₁ −c ₂ + a ₂ ) (9)
Since it is desired to obtain the propagation time e _1, it is necessary to know the transmission times c ₁ and c ₂ and the propagation time a ₂ as is apparent from the equation (9). 5 and the length between slave stations of the communication line 8.
[0021]
Accordingly, the length of the cable or communication line must be obtained every time the equipment is changed, and the transmission times c ₁ and c ₂ and the propagation time a ₂ as correction terms must be obtained.
It is good when the number of installations is short and the number is small, but in the case of a long and complex distribution network, if 100 sensors and 100 slave stations corresponding to them are provided, each sensor will be supported. It is necessary to measure the total length of 100 cables for the cables connecting the slave stations, and know the length between any two slave stations for the length of the communication line between the slave stations. Because you need
(1/2) · (100-1) × 100 = 4950 It is not practical because the length of the communication line needs to be actually measured or calculated from the map (second and third) problem).
[0022]
Furthermore, in the case of a cable or communication line, the permittivity changes with temperature, and the transmission time of the needle wave detection signal and the propagation time of the time reference signal change.
[0023]
However, in reality, there is another problem that it is impossible to perform temperature correction by distinguishing between a portion exposed to sunlight and a shaded portion.
Therefore, an object of the present invention is to provide a method for locating a needle wave generation point in a distribution line that can eliminate these problems.
[0024]
[Means for Solving the Problems]
In order to achieve the object, the invention of claim 1
Needle-like waves generated at the micro ground fault point (E) are detected by at least two sensors (2) (3) arranged at intervals on the distribution line (1), and each sensor (2) ( 3) The detection signals from 3) are transmitted to the slave stations (6) and (7) through the cables (4) and (5), respectively, and the slave stations (6) and (7) send the received detection signals to the appropriate signal form information. As a time reference signal (A) from the master station (9) to the slave stations (6) (7) via the communication line (8). ) Is intermittently transmitted to calibrate the internal clock of the slave stations (6) and (7).
Forcibly injecting another signal (B) into the distribution line (1) and detecting the signal (B) with the sensors (2) and (3) via the cables (4) and (5) Transmit to slave stations (6) and (7)
The time (R ₁ ) (R ₂ ) when the detection signal obtained by detecting the signal (B) by the sensors (2) and (3) is received by the slave stations (6) and (7), and the acicular wave is detected by the sensor (2) ( 3) From one sensor (2) to the micro ground fault point (E) based on the time (E ₁ ') (E ₂ ') when the detection signal detected in 3) is received by the slave station (6) (7) A method for locating a needle wave generation point in a distribution line, characterized by locating a distance (L ₁ ).
[0025]
And the invention of Claim 2 is the location method of the acicular wave generation | occurrence | production point in the distribution line of Claim 1,
The time difference (R ₂ −R ₁ ) between the times (R ₁ ) and (R ₂ ) of receiving the detection signals detected by the sensors (2) and (3) at the slave stations (6) and (7); Time difference (E ₂ ′ −E ₁ ′) of time (E ₁ ′) (E ₂ ′) at which the slave station (6) (7) received the detection signal detected by the sensor (2) (3). The distance (L ₁ ) from one sensor (2) to the minute ground fault point (E) is determined.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
1 is a block diagram of a preferred embodiment of a method for locating a needle wave generation point in a distribution line of the present invention, FIG. 2 is a time chart for explaining the operation of the block diagram of FIG. 1, and FIG. 3 is a distribution line of FIG. 4 is a circuit diagram of a signal injection device for injecting the signal B into the circuit, and FIG.
[0027]
In these drawings, reference numeral 1 denotes a three-phase high-voltage distribution line, which is fed by a transformer provided at a left substation (not shown). Reference numerals 2 and 3 are optical sensors provided on the distribution line 1 at intervals. The optical sensors 2 and 3 detect the zero-phase current I ₀ and the zero-phase voltage V ₀ having a needle-like waveform generated at the minute ground fault point E, and output detection signals. The signals are transmitted to the slave stations 6 and 7 by optical cables 4 and 5, respectively.
[0028]
A communication line 8 is a coaxial cable that connects the master station 9 and the slave stations 6, 7, etc. provided in the substation, and transmits various control signals from the master station 9 to the slave stations 6, 7, etc. At the same time, information from the slave stations 6 and 7 is transmitted to the master station 9. Note that the drive power (low power) for the slave stations 6 and 7 may be supplied from the low voltage distribution line, or may be sent from the master station 9 or the like via the communication line 8.
[0029]
A is a time reference signal for calibrating the internal clocks of the slave stations 6 and 7, and is a pulse-like electrical signal repeatedly sent from the master station 9 to the communication line 8 at a constant interval (period).
[0030]
P is an arbitrary point on the distribution line 1 and the communication line 8, a ₁ is a propagation time for the time reference signal A to propagate from this point P to the slave station 6, and a ₂ is a time reference from the slave station 6 to the slave station 7. This is the propagation time for signal A to propagate.
[0031]
B is a pulse signal forcibly deliberately injected into the distribution line 1. The injection timing may be arbitrary, but a signal injection device 10 in which a capacitor 11 and a short-circuit switch 12 are connected in series as shown in FIG. In the case of this embodiment in which the short-circuit switch 12 is momentarily closed for a short time by inserting it between the electric wire 1 and the ground and injecting the pulsed signal B, as shown in FIG. The signal B is injected at a phase away from the position of the zero cross point 14.
[0032]
t ₁ is a delay time from when the signal A passes through the point P to when the signal B passes, b ₁ is a propagation time for the injected signal B to propagate to the photosensor 2, and b ₂ is a signal B from the photosensor 2. It is the propagation time which propagates from to the optical sensor 3.
[0033]
e ₁ and e ₂ are propagation times for the needle-like wave generated at the micro ground fault point E to propagate on the distribution line 1 to the optical sensors 2 and 3, respectively, c ₁ and c ₂ are the optical sensors 2 and 3, and the signal B And the detection time for detecting the needle-like wave is the transmission time for transmitting to the slave stations 6 and 7 via the optical cables 4 and 5, respectively.
[0034]
Further, h ₀ is a detection delay time until the optical sensors 2 and 3 detect the signal B and the acicular wave and output a detection signal.
In the system of FIG. 1, a pulsed signal B is forcibly and intentionally injected into the distribution line 1 at an arbitrary timing. Looking at the time reference signal A and the signal B at the point P, FIG. 1 shows that the signal B is later by the delay time t ₁ after the passage of the time reference signal A.
[0035]
After passing the point P, the time reference signal A takes the propagation time a ₁ and reaches the slave station 6, and the signal B takes the propagation time b ₁ after injection and reaches the optical sensor 2.
The optical sensor 2 detects the signal B and transmits the detection signal to the slave station 6 via the optical cable 4 with a delay of the detection delay time h ₀ . The transmission time for transmitting the detection signal of the signal B from the optical sensor 2 to the slave station 6 requires c ₁ .
[0036]
The propagation speed at which the time reference signal A propagates on the communication line 8 and the propagation speed at which the signal B propagates on the distribution line 1 are different if the line constants of the communication line 8 and the distribution line 1 are different.
[0037]
When the time further elapses, the time reference signal A reaches the slave station 7 after passing the propagation time a ₂ after reaching the slave station 6, and the signal B passes through the propagation time b ₂ after reaching the optical sensor 2. Reach 3
[0038]
The signal B reaching the optical sensor 3 is output from the optical sensor 3 to the optical cable 5 after the detection delay time h ₀ , and is received by the slave station 7 through the transmission time c ₂ .
At the point P, the time difference between the time reference signal A and the signal B is t ₁ , but after the time reference signal A arrives at the slave station 6, the slave station 6 detects the detection signal detected by the optical sensor 2. a time R ₁ to the reception, after reaching the time reference signal a to the child station 7, the time R ₂ of a detection signal of the signal B is the optical sensor 3 detects until slave station 7 is received,
R ₁ = (b ₁ + h ₀ + c ₁ ) −a ₁ (10)
R ₂ = (b ₁ + b ₂ + h ₀ + c ₂ ) − (a ₁ + a ₂ ) (11)
It becomes.
[0039]
These times R ₁ and R ₂ are sent to the master station 9 via the communication line 8 as appropriate signal form information and stored in a memory (not shown) provided in the master station.
The time reference signal A is intermittently transmitted through the communication line 8 at a constant time interval (period) 、, and the internal clocks of the slave stations 6 and 7 are repeatedly calibrated. Compared to the internal timepiece 6, it is delayed by the propagation time a ₂ as described above.
[0040]
In this state, when a needle-like wave is generated at a fine ground fault point E on the distribution line 1, the needle-like wave reaches the optical sensors 2 and 3 after a lapse of propagation times e ₁ and e ₂ .
Then, the optical sensors 2 and 3 detect the detection delay time h ₀ , and the respective detection signals are received by the slave stations 6 and 7 via the optical cables 4 and 5 through the transmission times c ₁ and c ₂ , respectively.
[0041]
FIG. 2 shows the timing from when the time reference signal A reaches the slave station 6 until the slave stations 6 and 7 receive the needle wave detection signals of the optical sensors 2 and 3, that is, the occurrence of a fine ground fault.
[0042]
If the time reference signal A reaches the slave station 6 and passes through and passes a time t ₃ , and if a fine ground fault occurs at a point E and a needle-like wave is generated, the slave station 6 is referenced based on the internal clock of the slave station 6. , 7 are time E ₁ ′, E ₂ ′ until the needle-shaped wave detection signals from the optical sensors 2, 3 are received respectively.
E ₁ '= t ₃ + e ₁ + h ₀ + c ₁ (12)
E ₂ ′ = t ₃ + e ₂ + h ₀ + c ₂ −a ₂ (13)
However, the expressions (12) and (13) have the same contents as the expressions (7) and (8).
[0043]
(12) The times E ₁ ′ and E ₂ ′ of the equation (13) are transmitted from the slave stations 6 and 7 to the master station 9 through the communication line 8 as information of appropriate signal forms.
The master station performs the following calculation using the previously stored times R ₁ and R ₂ and the times E ₁ ′ and E ₂ ′ transmitted from the slave station.
[0044]
First, from the previously stored times R ₁ and R ₂ ,
R ₂ −R ₁ = b ₂ + c ₂ −c ₁ −a ₂ (14)
However, since b ₂ = e ₁ + e ₂ as apparent from FIG. 1,
R ₂ −R ₁ = e ₁ + e ₂ + c ₂ −c ₁ −a ₂ (15)
It becomes.
[0045]
From the time E ₁ ′ and E ₂ ′ for the needle wave,
_{E 2 '-E 1' = e} 2 -e 1 + c 2 -c 1 -a 2 ··· (16)
It becomes.
[0046]
Therefore, the time difference (R ₂₎ between the time R ₂ and the time R _{1 when} the slave stations 6 and 7 respectively received the detection signals detected by the optical sensors 2 and 3 forcibly and intentionally injected into the distribution line 1 by the optical sensors 2 and 3. −R ₁ ) and the time difference (E ₂ ′ −E ₁ ′) between the time E ₁ ′ and E ₂ ′ when the slave stations 6 and 7 received the detection signals detected by the optical sensors 2 and 3, respectively. From the above, the master station 9 obtains the propagation time e ₁ as shown in the following equation (17).
[0047]
(1/2) · {(R ₂ −R ₁ ) − (E ₂ ′ −E ₁ ′)} = e ₁ (17)
When the (17) multiplying the propagation rate Ve on distribution line 1 in formula, the distance L ₁ from the light sensor 2 to a fine ground絡発dough point E can be calculated orientation as the following equation (18).
[0048]
L ₁ = (1/2) · {(R ₂ −R ₁ ) − (E ₂ ′ −E ₁ ′)} · Ve (18)
Expression (18) does not include the propagation speed of the time reference signal A on the communication line 8. Therefore, even if the temperature of the communication line 8 changes and the propagation speed of the signal on the communication line 8 changes, the accurate distance L ₁ can be determined without being affected by the change. This means that the accurate distance L ₁ can be determined even if the temperature distribution on the communication line is not uniform.
[0049]
Since the distribution line 1 is usually aerial, it is air-insulated in this case, and the propagation velocity Ve does not change even if the temperature changes. Even if the distribution line 1 includes an underground cable, since the underground temperature is kept substantially constant, there is no possibility of causing a large orientation error.
[0050]
Incidentally, if there is a 1% error in the signal propagation speed due to a change in the temperature of the communication line, regardless of the method of the present invention, a standardization of 30 m corresponding to 1% when measured in a section of about 3 km. When an error is generated and the distance between the power poles of the distribution line is taken into consideration, it is identified as a different power pole, and a problem remains in practice.
[0051]
Furthermore, the expression (18) has an advantage that the transmission times c ₁ and c ₂ of the optical cables 4 and 5 are canceled on the right side thereof, so that the length of the optical cables 4 and 5 is not affected.
[0052]
The present invention requires at least two sensors for detecting the acicular wave, and in the above embodiment, the generation position of the acicular wave in the section in which the sensor is provided is determined.
[0053]
If three or more sensors are provided, a result is obtained for each two of them, and an operation such as obtaining an average value is performed, then the orientation accuracy can be further increased.
In addition, the operation of injecting the signal (B) into the distribution line and automatically storing the time signal (R ₁ ) (R ₂ ) in the master station (9) includes switching the distribution line and installing sensors and slave stations. This is done when the point is changed and when the temperature change becomes large.
[0054]
Each slave station has a function of discriminating whether the needle wave comes from the right side or the left side of the sensor, so that the fine ground fault point (E) has two sensors (2) (3). Even if it is not between, it can be determined from the right side or the left side, and the reliability is further improved.
[0055]
【The invention's effect】
Since the method of locating the needle wave generation point in the distribution line of the present invention is configured as described above,
1). Since the laying distance of the communication line (8) is automatically corrected by the equation (18) and becomes irrelevant, it is not necessary to actually measure the communication line (8) for every laying of the communication line (8) or obtain it on a map.
[0056]
2). Since the lengths of the cables (4) and (5) for transmitting the detection signals from the sensors (2) and (3) to the slave stations (6) and (7) are automatically corrected by the equation (18) and are irrelevant. Similar to the line (8), it is not necessary to actually measure or obtain the length on the map.
[0057]
3). The propagation speed and transmission speed of signals on the communication line (8) and the cables (4) and (5) for transmitting the detection signals from the sensors (2) and (3) to the slave stations (6) and (7) are also expressed by the formula (18). Since it is automatically corrected and becomes irrelevant, there is no possibility of adverse influence on the orientation error due to temperature change.
[0058]
4). Accordingly, the attachment positions of the slave stations (6) and (7) corresponding to the sensors (2) and (3) do not need to be closest, and may be arbitrary positions, and there is a degree of freedom of the attachment positions.
5). The power transport route is often changed by switching the distribution line, but even in such a case, it is not necessary to measure the distance by actual measurement or a map.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the present invention.
FIG. 2 is a time chart for explaining the operation of the block diagram of FIG. 1;
3 is a circuit diagram of a signal injection device that injects a signal B into the distribution line of FIG. 1;
FIG. 4 is a diagram illustrating a voltage waveform of a distribution line into which a signal B is injected.
FIG. 5 is a block diagram of the prior art.
[Explanation of symbols]
1 Distribution lines 2, 3 Optical sensor (sensor)
4, 5 Optical cables 6, 7 Slave station 8 Communication line 9 Master station 10 Signal injection device B Other signal E Slight ground fault occurrence point E ₁ ', E ₂ ' Time L ₁ Distance R ₁ , R ₂ Time R ₂ -R ₁ hour difference E ₂ '-E ₁ ' time difference

Claims (2)

Needle-like waves generated at the micro ground fault point (E) are detected by at least two sensors (2) (3) arranged at intervals on the distribution line (1), and each sensor (2) ( 3) The detection signals from 3) are transmitted to the slave stations (6) and (7) through the cables (4) and (5), respectively, and the slave stations (6) and (7) send the received detection signals to the appropriate signal form information. As a time reference signal (A) from the master station (9) to the slave stations (6) (7) via the communication line (8). ) Is intermittently transmitted to calibrate the internal clock of the slave stations (6) and (7).
Forcibly injecting another signal (B) into the distribution line (1) and detecting the signal (B) with the sensors (2) and (3) via the cables (4) and (5) Transmit to slave stations (6) and (7)
The time (R ₁ ) (R ₂ ) when the detection signal obtained by detecting the signal (B) by the sensors (2) and (3) is received by the slave stations (6) and (7), and the acicular wave is detected by the sensor (2) ( 3) From one sensor (2) to the micro ground fault point (E) based on the time (E ₁ ') (E ₂ ') when the detection signal detected in 3) is received by the slave station (6) (7) A method for locating a needle wave generation point in a distribution line, characterized by locating a distance (L ₁ ). The time difference (R ₂ −R ₁ ) between the times (R ₁ ) and (R ₂ ) of receiving the detection signals detected by the sensors (2) and (3) at the slave stations (6) and (7); Time difference (E ₂ ′ −E ₁ ′) of time (E ₁ ′) (E ₂ ′) at which the slave station (6) (7) received the detection signal detected by the sensor (2) (3). The method for locating a needle wave generation point in a distribution line according to claim _{1, wherein} a distance (L ₁ ) from one sensor (2) to a minute ground fault point (E) is determined.

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