JP2012108011A - Fault point orientation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fault point orientation method that can orient a fault point with high accuracy even if surge generated by an accident is attenuated as it is transmitted along a rail track.SOLUTION: A fault point orientation method comprises the steps of: measuring and storing a surge waveform of each end of a rail track that supplies power upon an accident in the rail track synchronously; picking up a waveform to which the stored surge waveform of each end of the rail track is most similar; obtaining a time difference between a time of the picked surge waveform of one end and a time of the picked surge waveform of the other end; and obtaining a distance from the one end of the rail track to a fault point based on the time difference to orient the fault point.

Description

  The present invention relates to an accident point locating method for locating an accident point when an accident occurs on a power supply line.

  For example, there is an accident point locating method for locating an accident point of a power supply line that is determined from a time difference at which a surge generated at the accident point instantaneously reaches both ends of the line (for example, non-patent) Reference 1). That is, the master station at one end of the line receives a surge and then starts a counter to count the time. The slave station at the other end of the line receives a surge and then generates a high-frequency signal and returns a pulse to the master station. Send as. Then, the master station counts the arrival time difference of the return pulses sent from the slave station after receiving the surge and determines the accident point. The surge in this case is a voltage surge or a current surge. In the case of locating the accident point from the time difference between the arrival of surges, the presence or absence of a surge at both ends of the line is determined by a threshold.

  FIG. 5 is an explanatory diagram of an accident point location method using a conventional threshold method. Now, consider the line position x with respect to one end of the line, and assume that the position of one end of the line is x = 0 and the position of the other end is x = L. Then, at time t (= 0), an accident occurs at a position F of xf from one end of the line, and surge u1 (t + x /) advances at a speed v from the accident point F (x = xf) toward both ends of the line. v), u2 (tx / v).

  Then, a threshold value ut is provided for the reception surge u1 at one end position (x = 0) of the line and the reception surge u2 at the other end position (x = L) of the line, and one end position (x = 0) of the line. ), The time t1 when the reception surge u1 exceeds the threshold ut is the surge reception time at one end position (x = 0) of the line, and the reception surge u2 at the other end position (x = L) of the line exceeds the threshold ut Let time t2 be the surge reception time at the other end position (x = L) of the line.

  As shown in FIG. 5, when the reception surge u1 exceeds the threshold value ut at one end position (x = 0) of the line, the distance from the front end of the reception surge u1 to one end position (x = 0) of the line is expressed as Δx1. Similarly, when the reception surge u2 exceeds the threshold ut at the other end position (x = L) of the line, the distance from the front end of the reception surge u2 to the other end position (x = L) of the line is Δx2. The following equations (1) and (2) are established.

xf + Δx1 = v · t1 (1)
L−xf + Δx2 = v · t2 (2)
From the equations (1) and (2), the relationship between the accident point F (x = xf) and the surge reception times t1 and t2 is represented by the equation (3).

xf = {L−v (t2−t1)} / 2+ (Δx2−Δx1) / 2 (3)
Here, assuming that Δx1 = Δx2, equation (3) is expressed by equation (4).

xf = {Lv (t2-t1)} / 2 (4)
L is known because it is the distance between both ends of the line, and the surges u1 and u2 that proceed from the accident point F (x = xf) toward both ends of the line are also known because they are values determined by the line. Therefore, when the time difference (t2−t1) is obtained by measuring the surge reception times t1 and t2 of the surges u1 and u2 at both ends of the line, the accident point F (x = xf) is obtained from the equation (4). Can be sought.

Electric Joint Research Vol. 34, No. 6 “Fault Locator Location Reliability Improvement Measures” pp. 10-11, February 28, 1979, published by Electric Joint Research Society

  However, since the surge attenuates as it propagates through the line, the surge waveforms of the surges u1 and u2 do not have the same magnitude unless the accident point F is at the center of the line. Therefore, since the threshold value ut at both ends of the line is set to the same value, an error may occur in the surge reception times t1 and t2, or one of the surges u1 and u2 may not be detected.

  FIG. 6 is an explanatory diagram in the case where an error occurs in the surge reception times t1 and t2 in the conventional fault location method using the threshold method. As shown in FIG. 6, when the attenuation of the surge u2 is large, the height of the surge u2 is small, and Δx2 when the surge u2 is received is larger than Δx1 when the surge u1 is received. Then, since the second term {(Δx2−Δx1) / 2} on the right side of the equation (3) is not zero, the second term on the right side of the equation (3) becomes an orientation error.

  FIG. 7 is an explanatory diagram when one of the surges u1 and u2 cannot be detected by the conventional fault location method using the threshold method. If the peak values of the surges u1 and u2 that reach the end of the line do not reach the threshold value ut, the surge cannot be detected. FIG. 7 shows a case where the surge u2 cannot be detected. As shown in FIG. 7, when the attenuation of the surge u2 is large, the peak value of the surge u2 does not reach the threshold value ut. t2 is not determined. Therefore, since the time difference (t2−t1) in the expression (3) or (4) is not determined, the accident point F (x = xf) is not determined.

  Therefore, it is conceivable to lower the threshold ut, but the threshold ut cannot be lowered unnecessarily for the following reason. When the threshold value ut is lowered, noise other than surge may be erroneously detected as surge. That is, due to noise that enters the surge detector or noise that occurs inside the surge detector, it may be erroneously detected as if the surge has arrived even though the surge has not reached.

  In the case of a one-line ground fault, a plurality of surges are generated from a high peak to a low peak, such as a preceding surge with a low peak value and re-ignition of a disappeared surge. For this reason, even if the threshold value is lowered, out of surges generated at the same time in a place close to one end of the line, it may be detected at one end and not detected at the other end. If it cannot be detected at the other end, the time difference (t2−t1) of the expression (3) or (4) is not determined, so the accident point F (x = xf) is not determined.

  An object of the present invention is to provide an accident point locating method capable of accurately locating an accident point even when a surge generated by an accident is attenuated as it propagates along a line.

  In the accident location method according to the invention of claim 1, when an accident occurs in a power supply line, the surge waveforms at both ends of the line are measured and stored in synchronization, and the stored surge waveforms at both ends of the line are stored. Take out the most similar waveform, find the time difference between the time of the surge waveform at one end and the time of the surge waveform at the other end, and find the distance from one end of the line to the accident point based on the time difference It is characterized by locating.

  In the accident point locating method according to the invention of claim 2, in the invention of claim 1, the time difference between the surge waveforms at both ends of the line represents the surge waveforms at both ends of the line as functions, and a correlation function of these functions is used. It is characterized by seeking.

  According to the present invention, the surge waveform having the most similar surge waveform at both ends of the line is taken out, the time difference between the time of the surge waveform at one end taken out and the time of the surge waveform at the other end is obtained, and from the time difference to the accident point Therefore, the accident point can be accurately determined even if the surge generated by the accident is attenuated as it propagates along the line. Further, since the time difference between the time of the surge waveform at one end and the time of the surge waveform at the other end is obtained using the correlation function, the accident point can be determined more easily and accurately.

The apparatus block diagram for implement | achieving the accident point location method which concerns on embodiment of this invention. Explanatory drawing of the surge in the one end position (x = 0) and the other end position (x = L) of the track | line in the accident point location method which concerns on embodiment of this invention. It illustrates the relationship between _u 01 (t) and _u 02 (t) at time t. The graph which shows the conceptual relationship between correlation function R (τ) and time difference τ. Explanatory drawing of the accident point location method by the conventional threshold value system. Explanatory drawing in case an error arises in surge reception time t1, t2 by the accident point location method by the conventional threshold method. Explanatory drawing when either one of surge u1 and u2 cannot be detected with the accident point location method by the conventional threshold method.

  Embodiments of the present invention will be described below. FIG. 1 is an apparatus configuration diagram for realizing an accident point location method according to an embodiment of the present invention.

  The transformer 12 a of the substation 11 a and the transformer 12 b of the substation 11 b are connected by a line 13. Surge detectors 14 a and 14 b and surge waveform measuring instruments 15 a and 15 b for detecting a surge generated in the line 13 are provided at both ends of the line 13. If a ground fault occurs on the line 13, a protective relay device (not shown) is operated, and an accident detection signal from the protective relay device is input to the surge waveform measuring devices 15a and 15b.

  When an accident detection signal is input to the surge waveform measuring devices 15a and 15b, the surge waveforms at both ends of the line 13 are measured synchronously from the surge detectors 14a and 14b. That is, the surge waveform measuring devices 15a and 15b receive the time from the GPS (Global Positioning System) 16, measure the surge waveforms detected by the surge detectors 14a and 14b in synchronization with the time, and measure the measured surge. The waveform is transmitted to the input processing unit 18 of the arithmetic and control unit 17.

  The input processing unit 18 stores the surge waveform input from the surge waveform measuring instruments 15 a and 15 b in the storage device 19. As a result, when an accident occurs on the line 13, the storage device 19 stores surge waveforms at each time at both ends of the line 13.

  Next, the time difference calculation means 20 is a combination of the surge waveform at one end and the surge waveform at the other end among the surge waveforms at both ends of the line stored in the storage device 19 with the largest degree of overlap. Take out the surge waveform. This is because surges that occur at the same time at the accident point and propagate to both ends of the line 13 may have a similar waveform even if they are attenuated and have different sizes when they reach both ends. Because there are many.

  When the time difference calculation means 20 extracts a surge waveform having the largest degree of overlap of surge waveforms, the time difference calculation means 20 obtains a time difference between the time of the extracted surge waveform at one end and the time of the surge waveform at the other end. This is because time is given to the surge waveforms measured by the surge waveform measuring instruments 15a and 15b. For example, when the time of the surge waveform at one end is t1 and the time of the surge waveform at the other end is t2 as a combination of surge waveforms having the largest degree of overlap of surge waveforms, (t2−t1) is obtained as the time difference. It is done.

  The accident point calculation means 21 determines the distance from the one end of the line 13 to the accident point based on the time difference (t2-t1) obtained by the time difference calculation means 20 to determine the accident point. For example, the distance xf from one end to the accident point is obtained using the above-described equation (4). The accident point obtained by the accident point calculation means 21 is displayed and output on the display device 23 via the output processing unit 22 as necessary. Further, it may be stored in the storage device 19.

  Next, the procedure of the accident location method according to the embodiment of the present invention will be described. First, as procedure 1, time information is added to and recorded on surges detected by the surge detectors 14a and 14b installed at both ends of the line. That is, the surge is recorded as a function of time and stored in the storage device 19. FIG. 2 is an explanatory diagram of surges at one end position (x = 0) and the other end position (x = L) of the line in the accident point location method according to the embodiment of the present invention.

  FIG. 2 shows that a plurality of surges A, B, and C generated from the accident point F propagate along the line while being attenuated and are transmitted to both ends of the line. Propagation as surges A1, B1, and C1 at one end position (x = 0) of the line, and propagation as surges A2, B2, and C2 at the other end position (x = L) of the line.

  The surges A1 to C1 and A2 to C2 include noises N1 and N2. The surges A1 to C1 and A2 to C2 that have propagated through the line are generated by the surge detectors 14a and 14b provided at both ends of the line. , N2 are detected. In FIG. 2, noises N1 and N2 are shown separately from surges A1 to C1 and A2 to C2.

  Now, let S1 (t) be the received signal detected by the surge detector 14a installed at one end position (x = 0) of the line, and the surge detector 14b installed at the other end position (x = L) of the line. Assuming that the received signal to be detected is S2 (t), the received signal S1 (t) is represented by equation (5), and the received signal S2 (t) is represented by equation (6).

S1 (t) = k1u ₀₁ (t) + N1 (t) (5)
S2 (t) = k2u ₀₂ (t−L / v) + N2 (t) (6)
Attenuation _{Here, u} 01 (t) is the surge at one end position (x = 0) of the line in the case of that there is no attenuation to the surge _{S1 (t), u 01 (} t) is the surge S2 (t) If there is no line, the surge at the other end position (x = L) of the line, N1 is the noise at one end position (x = 0) of the line, and N2 is the noise at one end position (x = L) of the line. .

  Further, k1 is a surge attenuation constant at one end position (x = 0) of the line, k2 is a surge attenuation constant at the other end position (x = L) of the line, and when the surge attenuation coefficient is α, the surge attenuation constant k1 is expressed by equation (7), and the surge attenuation constant k2 is expressed by equation (8).

k1 = exp (−αxf) (7)
k2 = exp {−α (L−xf)} (8)
Next, as the procedure 2, the received signals S1 (t) and S2 (t) recorded in the procedure 1 are arranged, the two are translated and compared, and the shifted time (time difference) when both waveforms are most similar to each other is compared. ) Find τ. The relationship between this time difference τ and the distance xf from one end of the line to the accident point F is as shown in the following equation (9).

(L−xf) −xf = v | τ | (9)
Here, as a specific example of the procedure for comparing the waveforms of the two signals of the received signals S1 (t) and S2 (t), using the correlation function R (τ) shown in the following equation (10), both ends of the line The case where the time difference τ of the surge waveform is obtained will be described.

R (τ) = ∫S1 (t) S2 (t + τ) dt (10)
τ represents a time in which the time of the waveform of the reception signal S2 (t) is shifted, and is a time difference from the reception signal S1 (t). In addition, the range of time for integrating the equation (10) is the range of time for measurement.

  When the expressions (5) and (6) are substituted into the expression (10), the expression (11) is obtained.

R (τ) = ∫ {k1u ₀₁ (t) + N1 (t)} {k2u ₀₂ (t−L / v) + N2 (t)} = ∫k1u ₀₁ (t) k2u ₀₂ (t−L / v) dt
+ ∫k1u ₀₁ (t) N2 (t) dt
+ ∫N1 (t) k2u ₀₂ (t−L / v) dt
+ ∫N1 (t) N2 (t) dt (11)
Here, u ₀₁ (t) and N 2 (t), N 1 (t) and u ₀₂ (t−L / v), and N 1 (t) and N 2 (t) are not correlated with each other. The values of the second term, the third term, and the fourth term on the right side of are very small values. Therefore, when the values of the second term, the third term, and the fourth term are set to zero, the equation (11) is expressed by the equation (12).

R (τ) = ∫k1u ₀₁ (t) k2u ₀₂ (t−L / v + τ) dt
= K1k2∫u ₀₁ (t) u ₀₂ (t−L / v + τ) dt (12)
Here, the relationship between the functions u ₀₁ (t) and u ₀₂ (t) in the equation (12) is examined. FIG. 3 is an explanatory diagram showing the relationship between u ₀₁ (t) and u ₀₂ (t) at time t.

In FIG. 3, it is assumed that the surge u ₀₁ (t) propagates to the distance d on the left side from the failure point F, and the surge u ₀₂ (t) propagates to the distance d on the right side from the failure point F. From FIG. 3, equation (13) holds.

u ₀₁ {t + (xf−d) / v} = u ₀₂ (t− (xf + d) / v} (13)
Here, the relationship between xf and d at one end position (x = 0) of the line is expressed by equation (14).

xf−d = 0 (14)
Substituting equation (14) into equation (13) yields equation (15).

u ₀₁ (t) = u ₀₂ (t−2xf / v) (15)
On the other hand, the relationship between xf and d at the other end position (x = L) of the line is expressed by equation (16).

xf + d = L (16)
If the equation (16) is substituted into the right side of the equation (13), the right side of the equation (13) becomes u ₀₂ (t−L / v). Therefore, the condition that can be made equal to (15) by shifting the time of u ₀₂ (t−L / v) at x = L by τ is obtained as the following equation (17).

t−L / v + τ = t−2xf / v (17)
Accordingly, the shift time τ is obtained by (18).

τ = (L−2xf) / v (18)
When the equation (18) is transformed, the distance xf from the one end position (x = 0) of the track to the accident point F is obtained as the equation (19).

xf = (L−vτ) / 2 (19)
At this time, the correlation function R (τ) of the equation (12) is expressed as the equation (20) with reference to the equations (7) and (8).

R (τ) = k1k2∫u ₀₁ (t) u ₀₂ (t−L / v + τ) dt
= Exp (−αxf) exp {−α (L−xf)} ｘ {u ₀₁ (t)} ² dt (20)
FIG. 4 is a graph showing a conceptual relationship between the correlation function R (τ) and the time difference τ. The relationship between the correlation function R (τ) and the time difference τ is conceptually as shown in FIG. 4, and when the correlation function R (τ) reaches the maximum Rmax, the received signals S1 (t) and S2 (t) Is the most similar, so the time difference τf at that time is obtained. Then, by assigning this τf to the equation (19), the distance xf from the one end position (x = 0) of the track to the accident point F is obtained, and thereby the accident point is determined.

  In this way, the surge waveform with the most similar surge waveform at both ends of the line is taken out, the time difference between the time of the extracted surge waveform at one end and the time of the surge waveform at the other end is obtained, and the distance from the time difference to the accident point Therefore, the accident point can be accurately determined even if the surge generated by the accident is attenuated as it propagates through the line.

  In the above description, the time is received from the GPS 16 and the surge waveform measuring devices 15a and 15b are synchronized, but another method may be used instead of the synchronization method using the GPS 16. For example, the synchronization may be performed using distributed clock synchronization such as the high-precision time protocol IEEE 1588, or may be synchronized with each other using a general communication line.

DESCRIPTION OF SYMBOLS 11 ... Substation, 12 ... Transformer, 13 ... Line, 14 ... Surge detector, 15 ... Surge waveform measuring device, 16 ... GPS, 17 ... Arithmetic control device, 18 ... Input processing part, 19 ... Storage device, 20 ... Time difference calculation means, 21 ... Accident point calculation means, 22 ... Output processing section, 23 ... Display device

Claims (2)

When an accident occurs on the power supply line, the surge waveforms at both ends of the line are measured and stored in synchronization,
Take out the waveform with the most similar surge waveform at both ends of the memorized line,
Find the time difference between the time of the surge waveform at one end and the time of the surge waveform at the other end,
An accident point locating method characterized in that a fault point is determined by obtaining a distance from one end of the track to the accident point based on the time difference.   2. The accident location method according to claim 1, wherein the time difference between the surge waveforms at both ends of the line is obtained by representing the surge waveforms at both ends of the line as functions, and using a correlation function of these functions.

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