JPS61215970A - Accident point location for cable line - Google Patents

Abstract

PURPOSE:To locate the accident point of the cable line by a special formula by impressing the calibration pulse or a high voltage at the measuring edge or the remote edge of the accident phase cable, measuring the propagation time in the measuring edge of the accident phase or sound phase cable. CONSTITUTION:A time difference t1 between a propagating signal detected at the measuring edge by impressing the calibration pulse to the measuring edge of an accident phase cable 2 and the second propagating signal, in which the calibration pulse is detected from the remote edge of the cable 2 through a sound phase cable 6 at the measuring edge, is calculated. A time difference t2 between the propagating signal detected at the measuring edge by impressing the calibration pulse to the remote edge of the cable 2 and the propagating signal, in which the calibration pulse is detected from the remote edge through a cable 6 at the measuring edge, is calculated. Further, a time difference t3 between the propagating signal wherein the high voltage is impressed from a high voltage source DCG to the cable 2 and a discharging pulse generated at an accident point A is detected at the measuring edge, and the propagating signal detected at the measuring edge from the remote edge through the cable 6, is calculated. Based upon time differences t1-t3 and a line length L of the accident phase, the accident A is located from the special formula.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for locating fault points on cable lines, and in particular,
We develop a method for locating fault points on cable lines that allows fault points to be located with high precision.

[Technical Background of the Invention] Conventionally, as shown in Fig. 5, as a fault point locating method for cable lines, high voltage is applied from a high voltage source DCG to the cable line in the fault phase, and the discharge generated at fault point A is applied to the cable line in the fault phase. The pulse is detected as a first propagation signal Sl by the capacitor C and the impedance Z at the measurement end of the cable line, and the discharge pulse is reflected at the measurement end and negatively reflected at the Keisei point of the cable line, resulting in a reverse polarity pulse. There is a known method in which the second propagation signal S2 is detected again at the measurement end, and the signal is located on the synchroscope M using an oscillogram. A typical example of the oscillogram at this time is shown in Fig. 6. The first propagation signal No. 18 Sl is a pulse directly propagated from the fault point A to the measurement end, and the second propagation signal S2 is a discharge pulse reflected at the measurement end. It shows a pulse that was negatively reflected at the fault point A of the cable line, became a reverse polarity pulse, and propagated again to the measurement end. Therefore, the time difference t between the first propagation signal St and the second propagation signal S2 at the measurement end is the time during which the pulse propagated back and forth between the fault point A and the measurement end, and the distance X from the measurement end to the fault point A is It is determined from the pulse propagation velocity V using the following formula.

,
The reflected wave s2° from the connection part enters between, and the time difference to'
There is a problem in that the position of the accident point A cannot be determined due to incorrect measurements.

In addition, the lead wire system at the measurement end of the fault phase, the lead wire system at the connection between the far ends of the fault phase and healthy phase, and the lead wire system at the measurement end of the sound phase strictly act as pulse delay elements. , which has the disadvantage of being a source of measurement error.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional difficulties, and it is an object of the present invention to provide a method for locating a fault point on a cable line by which the fault point can be located with high precision.

[Summary of the Invention] In order to achieve the above object, according to the cable line fault location method of the present invention, a calibration pulse is applied to the measurement end of the cable line in the fault phase, and the first point detected at the measurement end is determined. Calculating the time difference tl between the first propagation signal and the second propagation signal, in which the calibration pulse is transmitted from the far end of the cable line to the measurement end via a healthy phase cable line and detected at the measurement end; A first propagation signal detected at the measuring end by applying a calibration pulse to the far end of the fault phase cable line and the calibration pulse are transmitted from the far end of the cable line to the healthy phase cable line to the measuring end. The time difference t2 between the second propagation signal that is transmitted and detected at the measurement end is calculated, and a high voltage is applied to the cable line of the fault phase, and the discharge pulse generated at the fault point is detected at the measurement end. The time difference t between the propagation signal and the second propagation signal, in which the discharge pulse is transmitted from the far end of the cable line to the measurement end via the cable line in a healthy phase and detected at the measurement end, is calculated; Locate the fault point on the cable line by finding the distance Mx from the measurement end to the fault point from x = (tl - t) Ll / (tl - t2) (where Ll is the cable line length of the fault phase). It is something to do.

[Embodiments of the invention] Preferred embodiments of the present invention will be described below with reference to the drawings.

The cable line accident point locating method of the present invention is realized by the system configuration shown in FIG. In other words, in the same figure, the cable line of the accident phase! The measurement end of j82 is connected to the high voltage source DCG and is grounded via the coupling capacitor C1 detection impedance Z. This capacitor C1 detection impedance Z is the fault point of the cable line (for example, A
) is detected as the first propagation signal S1. The midpoint between the capacitor C and the impedance Z is connected to the digital memory 40 channel CHl by a lead wire system 3 at the measuring end of the fault phase.

It is assumed that the lead wire system 3 includes a delay element 5 having a delay time T1. On the other hand, the far end of the cable line 2 is grounded via a capacitor C and an impedance Z, and the midpoint between the capacitor C and the impedance Z is connected to the far end of the cable line 6 in a healthy phase by a lead wire system 7. This capacitor C and impedance Z prevent the high voltage applied to the fault phase from being applied to the healthy phase, and allow the discharge pulse generated at the fault point A of the cable line to pass through to the healthy phase. It is assumed that the lead wire system 7 includes a delay element 8 having a delay time T2. Healthy phase cable line 6
The measurement end of is grounded via capacitor C and impedance Z, and the midpoint between capacitor C and impedance Z is connected to channel CH2 of digital memory 4 by lead wire system 9 at the measurement end of the healthy phase. It is assumed that the lead wire system 9 includes a delay element 10 having a delay time T3. This capacitor C and impedance Z transmit the discharge pulse generated at the fault point A of the cable line 2 from the far end of the cable line 2 to the measurement end via the cable line 6 in a healthy phase, and at the measurement end, a second propagation signal is generated. This is detected as S2. The output end of the digital memory 4 is connected to the location device 11. Note that both channels CHI and CH2 of the digital memory 4 are triggered by the first propagation signal S+.

In such a system configuration, fault point location on a cable line according to the present invention is performed by the following procedure.

■ A calibration pulse is applied to the measurement end of the cable line 2 in the fault phase, and the first propagation signal S+, which is propagated through the cable line 2 and detected at the measurement end, and the calibration pulse are transferred from the far end of the cable line to the healthy phase. A second propagation signal s2 transmitted to the measurement end via the cable line 6 and detected at the measurement end is taken into the digital memory 4, and the time difference t is
1 and transfers this data to the location device 11. This time difference t1 is tl=T3+T2-T1+ (Ll+L2)/V・
-...-(1) (Fig. 2(a)), where Ll
, L2 is the cable line length of the fault phase and healthy phase, and ■ is the pulse propagation speed.

■ A calibration pulse is applied to the far end of the cable line 2 in the fault phase, and the first propagation signal St, which is propagated through the cable line 2 and detected at the measurement end, and the calibration pulse are transmitted from the far end of the cable line 2 to the normal state. A second propagation signal s2 transmitted to the measurement end via the phase cable line 6 and detected at the measurement end is captured into the digital memory 4, the time difference t2 is calculated, and this data is transferred to the location device 11. do. This time difference t2 is t2=73+72-TI+ (L2-L2)/V...
...... (2) (Figure 2 (1))).

(]), from equation (2), the propagation velocity ■ is ν=2LI/(tl-t2)...
...It is obtained by (3).

■ Apply high voltage to the accident cable a12 from the high voltage source DCG. Assume that a discharge pulse occurs at a fault point A, for example. This discharge pulse propagates through the cable line 2 and is detected at the measurement end.The first propagation signal S1 and the discharge pulse are transmitted from the far end of the cable line 2 to the measurement end via the cable line 6 in a healthy phase. and the second propagation signal S2 detected at the measurement end are taken into the digital memory 4, the time difference t is calculated, and this data is sent to the location device 1.
Transfer to 1. This time difference t is t = 73+72-TI+ (L2+L1-2X)
/V=73+72-TI+((L2-L2)+2(L
l-X))/V Substituting equations (2) and (3) into this, we get t = t2+2(Ll-X)/V =, t2+(Ll-XXtl-12)/Ll (see Figure 2). C)).

Therefore, the distance X from the measurement end to the accident point is x = (
tl-t)Ll/(tl-t2), the position can be calculated using the location device 11, and the calculation result can be printed out using the attached printer. In this way, the cable line length Ll of the known fault phase can be measured #I! II
The distance MX is calculated only from It1, tl, and t, and the fault point on the cable line can be accurately located without being affected by the delay times T1, T2, and T3 of the delay element 5.8.1°.

In addition, since the healthy phase is used when transmitting the discharge pulse heading from the fault point to the far end to the measurement end, even if the line includes the normal junction box part NJ (Figure 3 (a)), ,
The time t (Fig. 3(b)) of the first propagation signal Sl and the second propagation signal S2 is accurately measured, and the fault point A is not affected by the reflected wave S2' from the normal junction box part NJ. It is possible to determine the position.

In addition, as shown in Fig. 4(a), the line is connected to the insulated junction box part I.
When grounded in the cross-bond manner by J, the insulating junction box induces the propagation wave of the discharge pulse to be branched from the fault phase to the healthy phase, so the discharge pulse traveling from the fault point to the sending end is connected to the healthy phase. Before reaching the measurement end, the discharge pulse running in the fault phase enters from the cross bond point, and the time difference t
(No. 41! I (b)) becomes unclear, making it impossible to locate the accident point. In this case, it is preferable to use the delay time T2 of the delay element 8 positively, that is, the delay time T2 of the delay element 8 is set to be longer than the time required for the propagation wave of the discharge pulse to be guided from the fault phase to the healthy phase. Therefore, after the induction from the fault phase to the healthy phase is completely eliminated, the discharge pulse heading from the fault point to the far end can be transmitted to the measuring end through the healthy phase, and the time difference t can be accurately determined, and the fault point location Orientation is possible.

[Effects of the Invention] As is clear from the above embodiments, according to the fault point locating method for cable lines of the present invention, when transmitting discharge pulses directed from the fault point to the far end to the measuring end, the cable in a healthy phase is detected. When a calibration pulse is applied to the measurement end of the fault phase cable line, when a calibration pulse is also applied to the far end, and when a high voltage is applied to the fault phase cable line, a discharge pulse is generated at the fault point. When generated, the first propagation signal and the pulse, which are respectively detected at the measuring end, are transmitted from the far end of the cable line to the measuring end via the cable line of a healthy phase and detected at the measuring end. Since the time difference with the second propagation signal is calculated and the distance from the measurement end to the fault point is determined, it is not affected by the delay time of the delay element and is not influenced by reflections at the cable line connection. Therefore, the accident point on the cable line can be accurately located without causing any problems.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram for realizing the cable line accident point locating method according to the present invention, Fig. 2 (a), (b),
(c) is a waveform diagram of the discharge pulse propagation signal obtained by the same orientation method, and Figures 3 (a) and (b) are a line system configuration diagram using a normal junction box to which the same orientation method can be applied, and its discharge pulse propagation signal. Figures 4(a) and 4(b) are a waveform diagram of a line system using an insulated junction box to which the same method can be applied, and a waveform diagram of its discharge pulse propagation signal, respectively.
FIGS. 5 and 6 are a system configuration diagram and a waveform diagram of a discharge pulse propagation signal used in the conventional accident point locating method, respectively. 203. The cable line Sl of the fault phase, . . . the first propagation signal 600. Healthy phase cable line S2. ,,Second. Propagation signals tl, t2, t000 time difference A81. Accident point X10. Distance Agent Patent Attorney Moritani-Yu Figures 3 and 4

Claims (1)

[Claims] A first propagation signal detected at the measurement end by applying a calibration pulse to the measurement end of the fault phase cable line and the calibration pulse connect the cable line of the healthy phase from the far end of the cable line. Calculate the time difference (t1) with the second propagation signal transmitted to the measuring end via the cable and detected at the measuring end, and apply a calibration pulse to the far end of the cable line of the fault phase to detect the signal at the measuring end. A second propagation signal, in which the first propagation signal and the calibration pulse are transmitted from the far end of the cable line through the cable line in good phase to the measuring end and detected at the measuring end.
The time difference (t2) between the first propagation signal and the first propagation signal detected at the measurement end by applying a high voltage to the cable line of the fault phase and the discharge pulse generated at the fault point is calculated. Calculate the time difference (t) between the far end of the cable line and the second propagation signal that is transmitted to the measuring end via the healthy cable line and detected at the measuring end, and calculate the time difference (t) from the measuring end to the fault point. A cable characterized in that a fault point on a cable line is located by finding the distance x from x=(t1-t)L1/(t1-t2) (where L1 is the cable line length of the fault phase). Railway accident point location method.