JPH04204391A - Trouble point orienting method for high voltage distribution line - Google Patents

Abstract

PURPOSE:To effectively cancel an influence of an induction current, even when it is generated during orientation, so as to orient a trouble point of earth fault with no error by obtaining a vector difference between before and after inverting polarity of currents in a sound line and all the distribution lines. CONSTITUTION:Thyristors SCR1, SCR2 are a circuit for applying an orienting power supply polarity-inverted by the predetermined timing to high voltage distribution lines A, B, and the timing of polarity inversion is performed by a signal from a control relay part 6. When orientation is performed in a short time, a value of an induction current is not changed. On the other hand, a current, flowing in each distribution line from the orienting AC power supply, is inverted before and after the polarity inversion of the orienting AC power supply. In a vector difference between a current, measured by a current transformer inserted in a sound line, before the polarity inversion of the power supply and a current after the polarity inversion, the current is generated not containing the induction current. Even when assumed that the induction current is mixed in a current flowing in a common line to which the orienting AC power supply is connected, a component of the induction current can be removed from the current flowing in the common line when the vector difference between the currents before and after the polarity inversion is taken out.

Description

[Detailed description of the invention] Main millet retired emperor five points! The present invention provides a so-called ground fault fault location method for locating the distance from the power transmission side to the ground fault point when a single-line ground fault occurs on a single-phase, two-wire high-voltage distribution line or three-phase high-voltage distribution line in a railway, etc. Regarding.

The present applicant previously proposed a conventional ground fault point locating method in Japanese Patent Application Laid-Open No. 59-230176. In this proposed method, when a ground fault occurs in a high-voltage distribution line, the ends of the high-voltage distribution line are short-circuited, and a locating AC voltage is applied between the power transmission side of the line and the ground, and this voltage and By applying this voltage, the current flowing through each line of the distribution line and the active power of each line are measured, and the ground fault point is located from the sum of the active power of all distribution lines and the active power ratio of only healthy lines. In this case, since the active power of each distribution line is in a proportional relationship with the current flowing through the distribution line, the ground fault point can be located using either the ratio of active power or the ratio of current.

FIG. 5 is a diagram showing the principle of location when a ground fault occurs in a single-phase, two-wire high-voltage distribution line.

In the figure, it is assumed that a ground fault has occurred at point X of one of the power distribution lines, %1ASB, and the end of the power distribution line is short-circuited, and
An AC power source for orientation is connected to the power transmission side.

Now, the total length of the distribution line is D, the distance from the power transmission side to the ground fault point is l, and the current flowing through all distribution lines is i.

("iA+il), and if the current of the healthy line A is iA, the following equation holds true.

to D In this formula, D is a known number, so 1A-i.

By measuring , it is possible to locate the distance from the power transmission side to the ground fault point X.

By the way, according to the above-mentioned locating method, simply detecting 50 and iA brings many advantages such as locating the ground fault point with simple calculations. Yes, but on the other hand,
There is a distribution line (not shown) of another system in parallel with either distribution line A or H, from which an induced current with the same frequency as the locating AC power supply or an integral multiple of the frequency flows into the distribution line. In this case, the conventional method described above has a problem in that an error occurs in the control point.

FIG. 6 is a diagram showing this. In the figure, at i, 1, an induced current from another distribution line flows in a loop across two distribution lines A and B. Due to this loop current i, the current detected by the current transformer CT to the healthy line is i71
' (=iA "is").As a result, the orientation operation becomes 2ia'l' □=□〉 □...(2) ioD D, and a point different from the true ground fault point is regarded as the ground fault point. This orientation error increases as the value of the induced current i,1 increases.

In the figure, the induced current iH is drawn to flow in the direction in which it is added to i at the healthy line A, but some induced currents may flow in the opposite direction, and in that case, the error will be at the true ground fault point. This will occur at a closer distance, similar to a ground fault.

Furthermore, when installed in parallel with an AC feeding circuit, induced current may also flow to the location power supply side, which also causes location errors.

In view of the above points, it is an object of the present invention to provide a new location method that can effectively offset the influence of induced current even if it occurs during location and locate a ground fault point without error. It is an object.

! In order to achieve the above-mentioned object, the present invention short-circuits the terminals of the high-voltage distribution kIIAB when a ground fault occurs in the high-voltage distribution line, and also connects the power transmission side of the line to the ground for orientation purposes. In a method for locating a ground fault fault point on a high-voltage distribution line, the ground fault fault point is located by applying an alternating current voltage and locating the ground fault fault point from the sum of the currents flowing through each distribution line due to this voltage and the value of the current flowing through healthy lines.
A means for reversing the polarity of the locating AC voltage is provided, and a vector difference between the current before polarity reversal and the current after polarity reversal of the AC voltage is used as the sum of the currents flowing through each distribution line and the current flowing through the sound lines. It is characterized by

Furthermore, when a ground fault occurs in a high-voltage distribution line, the present invention short-circuits the ends of the high-voltage distribution line, applies an alternating current voltage for orientation between the ground on the power transmission side of the distribution line, and A location method in which the active power of each line is measured from the current flowing through each distribution line due to the application of this voltage, and the ground fault point is located from the ratio of the sum of the active power of all distribution lines and the active power of a healthy line. In addition to providing means for reversing the polarity of the locating AC voltage, the current before polarity reversal and the current after polarity reversal of the AC voltage are calculated as the sum of the currents flowing through each distribution line and as the current flowing through the sound lines. It is characterized by the use of vector differences.

If orientation is performed in a short time, the induced current iHO value will not change. On the other hand, the current flowing from the locating AC power source to each distribution line is
The polarity is reversed before and after reversing the polarity of the locating AC power supply. now,
If the induced current is i, 4, and the current flowing from the locating AC power supply to power distribution 1 (healthy line) is i, the current measured by the current transformer inserted into the sound line before the polarity reversal of the power supply is i, i. is (i
g+ix), and the current iA'' after polarity reversal is (-i
A+i, 4). Vector difference between these two currents (1
1i,', lZ) is (ia+i+<) (iA”
iM)=2iA, which is a current that does not include the induced current i,4.

FIG. 4 is a waveform diagram illustrating this. Figure (A) shows that i changes before and after polarity reversal. Figure (b) shows the induced current waveform, and this waveform does not change before and after polarity reversal. Figure (A) shows the current measured in a current transformer with a healthy vAA, iA in Figure (A) and i4 in Figure (B).
This is the current that is a composite of the From the figure (c), it can be seen that the magnitude and polarity of the composite current change before and after polarity reversal.

Figure (d) shows i,'' after polarity reversal in figure (c) by 180°.
It shows a shifted state. Figure (E) is i in Figure (C).
Synthesize A L and -iA 11 in Figure (d) (iA'
ia”) Lz current.As can be seen from this figure,
iA ′ ° ″ is a current with a peak value twice that of -l ^ iA in figure (A). In this case, the induced current iH is canceled out by the calculation process of iA 1.i, ll, so The current in Figure (e) does not include induced current.

Similarly, even if an induced current is mixed in the current flowing in the common line to which the locating AC power supply is connected (equal to the sum of the currents flowing in all distribution lines), if we take the vector difference of the current before and after polarity reversal, then , the induced current can be removed from the current flowing through the common line.

Therefore, by finding the vector differences before and after polarity reversal between the current in the healthy line and the current in all distribution lines, and taking the ratio of each vector difference, the ground fault point can be located in a form that does not include the induced current component. It can be carried out.

Furthermore, the influence of induced current can be removed from the ratio of active power obtained by the inner product of the vector difference of the currents and the voltage of the locating power source, and accurate ground fault point locating can be performed.

FIG. 1 shows an example in which the method of the present invention is applied to a single-phase, two-wire high-voltage distribution line. In the figure, A and B are high-voltage distribution lines, and AC circuit breakers 1 are inserted in series on the power transmission side, and a short circuit switch 2 (vacuum switch 42s) is connected between the lines on the terminal side.

When a ground fault occurs, the AC circuit breaker 1 is interrupted by a trip signal from a ground protection relay (not shown) that detects the fault. The shorting switch 2 is closed by suitable means after the occurrence of a ground fault, shorting the terminal distributions '4IAA, B.

A locating current supply '41A3.4 is connected to the high voltage distribution lines A and B near the AC circuit breaker 1. A vacuum switch 42D is inserted in the middle of this supply line 3.4, and the other end of the supply line 3.4 is connected to one common line 5. The vacuum switch 42D is turned on by an instruction from the control relay part 6, and the vacuum switches 42D and 423 are controlled at the same time.

A locating power supply circuit 7 is connected to the common line 5 and the ground.

The locating power supply circuit 7 is an AC 200V AC power supply (not shown)
, electromagnetic switch MS, limiting resistor R, thyristor 5CRI
, 2 and a step-up transformer T. Electromagnetic switch M
S is turned on by a signal from the control section 6. The limiting resistor R is a resistor for supplying a constant current to the high voltage distribution lines A and B during location. The thyristors 5CRI, 2 are circuits for applying the locating power supply AC 200 V to the high voltage distribution lines A, B with the polarity reversed at a predetermined timing, and the timing of the polarity reversal is determined by a signal from the control relay part 6. The step-up transformer T is used to apply the same voltage to the high-voltage distribution line during orientation as during normal power transmission. The secondary side of this step-up transformer T is connected between the common line 5 and the ground.

Current transformers 8.9 are installed on the common line 5 and the oriented current supply line 3.4, respectively.
．． 10 is provided to detect the current flowing during orientation. Further, on the secondary side of the step-up transformer T, there is provided an instrument transformer 11 for detecting the locating voltage E. The currents and voltages detected by these current transformers 8, 9, 10 and the instrument transformer 11 and the orientation command issued from the control relay section 6 are input to the measuring section 12.

When a ground fault occurs, the control relay part 6 operates based on an instruction from a known detection device (not shown), and outputs a vacuum switch 42D activation signal (
Figure (b)), electromagnetic switch MS activation signal (same (c)), 5
Outputs CRI, 2 gate signals (d), (e), and orientation command (d).

In FIG. 2, for example, the vacuum switch 42D activation signal and the electromagnetic switch MS activation signal remain on for 5 seconds. The gate signal of 5CRI turns on at the same time as each activation signal, and then turns off two seconds later. On the other hand, the gate signal of 5CR2 turns on at the same time as the off edge of the gate signal of 5CR1, and turns off in synchronization with the off edge of the vacuum switch 42D actuation signal. The orientation command issues a trigger-like pulse simultaneously with the off-edge of the 5CRI gate signal. Figure 2 (to)
The sequence of calculation data is that of the measurement unit 12.

Although not shown, the off operation of the AC circuit breaker 1 is completed before the vacuum switch 42D activation signal is turned on.

The measurement unit 12 has a hardware configuration using a CPU, ROM, RAM, and input/output interface, and performs measurement operations according to the procedure shown in FIG. 3.

Next, the operation of the measuring section 12 will be explained based on FIG. First, the measurement unit 12 constantly monitors current and voltage through the current transformers 8.9.10 and the measurement transformer 11 (#
1). In this case, each current and voltage is temporarily stored at each instant up to at least five cycles past that point in time.

In this state, when the orientation command is input from the control relay part 6 (#2), the CPU takes in the orientation current and voltage for 5 cycles before the orientation command is input (#3).
). Next, the locating current and voltage for five cycles after the input of the locating command are fetched (#4), and predetermined calculations are performed together with the current and voltage fetched in #3 (#5). The calculation result is output as the orientation result (#6).

Operation #5 is performed as follows.

First, the following two equations are calculated.

iA l-i, 17...(3) i,'-1. // ...(4) Since the current in the distribution line that caused the ground fault is larger than the current in the healthy line, compare the magnitudes of the calculated values of the above two equations and select the smaller value to determine whether the line is healthy. Select current.

Next, the following calculation is performed using the current selected in the above calculation (for example, the healthy line is taken as A) as a numerator, and the orientation calculation is completed.

(io 'to'') 16=□・
...(5) Here, i, r, iA', ill' are currents flowing through the common line 5 and high-voltage distribution lines A and B before polarity reversal, and i. ″,i
A′J,i,″ is the current flowing through the common 15 high-voltage distribution lines A and B after polarity reversal.

Among the above equations (2), the equation whose numerator is the current i,′,i,″ flowing through the distribution line that is experiencing the ground fault (say, B) has a calculated value of approximately 2; The calculated value of the equation whose numerator is the current iAJ, ゛e'' flowing through a healthy line (for example, A) is a value smaller than 2. Therefore, correct orientation can be performed by comparing the magnitudes of the calculated values of equation (2) above and selecting the smaller value.

It should be noted that by executing the above calculation, the orientation value is not affected by the induced current, as explained in the operation section, so the explanation here will be omitted.

In the above embodiment, both 1Ilil#l, high voltage distribution lines A and B
Although the ground fault point is located using the current flowing in each line, it is also possible to locate the ground fault point from the ratio of active power consumed in each line. In this case, the following calculation formula is used.

2Ee ・(iA ′-1A ″)E, ・(io
1-io//)Wo'-W0”
D In the above equation, Ec is the voltage detected by the instrument transformer.

Using the method of locating the ground fault point using the ratio of the active power of each line, it is possible to locate the ground fault point accurately even if the ground fault resistance (resistance between the ground fault point and the earth) is not zero and has a finite resistance value. This has a greater effect than being able to locate the target.

In the embodiment, the method of the present invention is applied to ground fault location on a two-wire high-voltage distribution line, but it goes without saying that the method of the present invention can also be applied to ground fault location on a three-wire high-voltage distribution line.

As explained above, according to the locating method of the present invention, the locating voltage is applied with the polarity reversed, and the vector difference of the current flowing through the sound line before and after the polarity reversal is calculated, as well as the vector difference of the current flowing through all the distribution lines. Since the ground fault fault point is located from the ratio of the vector difference or the ratio of the active power given by the inner product of the vector difference of the current and the specified power supply voltage, the influence of the current induced from the distribution lines of other systems can be ignored. It is possible to effectively remove the ground fault and accurately locate the ground fault point.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a high-voltage distribution line locating device to which the method of the present invention is applied, Fig. 2 is a diagram showing the operation sequence of each part, Fig. 3 is a flowchart showing the operation performed by the measuring section, and Fig. 4 is FIG. 5 is a waveform diagram showing the principle of the method of the present invention, FIG. 5 is a diagram explaining the conventional orientation method, and FIG. 6 is a diagram explaining the problems thereof. Patent applicant: Tsuda Electric Meter Co., Ltd. West Japan Railway Company Figure 2 (A) 42S Figure 3

Claims (2)

[Claims] (1) When a ground fault occurs on a high-voltage distribution line, short-circuit the ends of the high-voltage distribution line, apply an AC voltage for orientation between the power transmission side of the line and the ground, and apply this voltage to each distribution line. In a method for locating a ground fault point on a high-voltage distribution line, which locates a ground fault point from the sum of currents flowing in the line and the value of the current flowing in a sound line, a means for reversing the polarity of the locating AC voltage is provided, and each distribution line A method for locating a ground fault point in a high-voltage power distribution line, characterized in that the vector difference between the current before polarity reversal and the current after polarity reversal of the alternating current voltage is used as the sum of the currents flowing in the line and as the current flowing in the sound line. (2) When a ground fault occurs in a high-voltage distribution line, short-circuit the ends of the high-voltage distribution line, apply an AC voltage for orientation between the power transmission side of the distribution line and the ground, and In the location method, the active power of each line is measured from the current flowing through each line of the distribution line due to the applied current, and the ground fault fault point is located from the sum of the active power of all the distribution lines and the ratio of the active power of the healthy line. Providing a means for reversing the polarity of the alternating current voltage, and using the vector difference between the current before and after the polarity reversal of the alternating current voltage as the sum of the currents flowing through each distribution line and the current flowing through the healthy lines. A method for locating the ground fault point of a high-voltage distribution line.