JPH0321876A - Faulty point locating device - Google Patents

Abstract

PURPOSE:To locate a fault with less error even at the time of reclosed circuit by using a current on faulty phase with changing-over as the input for a locating calculation block during a limit time recovering timer is continued to operate after the time set by a limit time operating timer. CONSTITUTION:When a ground fault is generated, a switching process 4a for polarity current data and a switching process 4b for phase voltage data are controlled in accordance with the output of a block 3 for sorting the ground fault phase to make the polarity currents 1a-1c and phase voltages 2a-2c so as to be the faulty phases. After a block 5 for starting the locating calculation for faulty point is operated by the operation of an fault detecting relay, a switch 8 for polarity current data is controlled to change-over the polarity current to the phase current after the operating time TA (about 200 seconds) of the limit time operating timer 6. This state is held during the operating time TB (about 5 seconds) of the limit time recovering timer 7 after the starting signal 5 according to the fault recovery is recovered. During the time TB, the polarity amount against the fault at a rethrowing time for reclosed circuit is not affected by an unbalanced load current between no voltage time zones for single phase reclosed circuit. The locating with less error can be calculated 9 accordingly.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is designed to reduce the secondary current input of a one-terminal voltage transformer in the event of a short circuit or ground fault in a power transmission line. Voltage transformer 2
This invention relates to a fault point locator that calculates the impedance from the next voltage input to the fault point and outputs the distance number.

(Prior Art) Figure 3 shows the installation status of a conventional distance type fault locator on a single line diagram. The fault point locator 11 is located at the own end electric station 12
When a failure 14 occurs in the power transmission line 13 connecting between the electrical station 12b and the electrical station 12b at the other end, the current transformer 15 of the line at its own end and the instrument transformer 16 installed on the busbar (or the instrument installed on the line) The distance from the own end 12a to the fault point 14 is calculated by impedance distance measurement using the input electricity from the transformer.Next, Fig. 4 shows the internal structure of the fault point locator 11. A block diagram is shown.Measurement current transformer 15,
The AC input from the instrument transformer 16 is applied to the analog data input section 17, where it is converted to a low voltage level and subjected to harmonic removal processing, and then sampled at regular intervals by the sampling hold section 18 to convert it into analog/digital data. The conversion unit 19 converts it into a digital amount and transfers it to the microprocessor (HPU) 20. Within the HPU 20, data is stored in memory, and processes such as distance measurement calculations and information interface with the outside are performed under instructions from the CPU.

Next, the principle of fault location calculation performed within this HPU 20 will be explained using FIG. In Fig. 5, the bus voltage at the own end 12a is V^, and the pre-fault current is I^. Let the current during the fault be ■^, the change in the current before and after the fault occurrence be I^", the voltage at the fault point be vF, the resistance at the fault point be Zr, and the impedance per unit length of the transmission line be Z. From the own end 12a to the fault point. If the distance to 14 is 1, then the following equation holds true.

vF=v^-I^ ・Z-J ・・・・・・
(1) In equation (1), vF is an unknown quantity and must be eliminated. Therefore, it can be assumed that the fault point resistance ZF is a pure resistance component, so if we use the fact that the current IF flowing into the fault point and the fault point voltage V, are in phase, Itn +VF
−IF ” l =O −=12) Note that IF4 is the conjugate complex number of IF. Also, IF=I^
- ■ 8 ′ 1 I 8 ・・・・・・(3
)(1), Substituting equation (3) into equation (2) eliminates VF, and In((V＾ I8 ・Z−ffl> ・IA
“”)=0.

It will be explained with reference to FIG. 6 that equation (4) holds true even when both power supplies are used. In other words, in Fig. 6, IP = (I
AIA')+(IsIB')...
...(5) Here, the current at the opposite end 12b is an unknown quantity for the own end 12a, but generally the changing current flowing from both ends (current flowing into the fault point) is 1. -IB' = k(I^-
I^'), equation (5) becomes IF = (1 +k
) IA --(6).

Here, k must be considered as a scalar quantity when the other end has a power supply, and as a vector quantity when the other end has no power supply, but in the latter case, the absolute value of k is very small and can be ignored. Therefore (
1) By substituting equation (6) into equation (2), the result is that the desired l is given in the same way as equation (4). however,(
Equation 4) is an equation that holds true regarding the phase in which the failure occurs, so in an actual three-phase system, I^. V^. It is necessary to switch the introduced phase for I^''.As an example, the short circuit/ground fault determination and failure phase determination logic in a directly grounded system are shown in FIGS. 8 and 7, respectively.

In Fig. 8, UV-ZA is an undervoltage relay with current compensation (line voltage judgment) installed in the own line. UV-Z is an undervoltage relay with current compensation (phase voltage determination), and OCG is a zero-sequence overcurrent relay element that is usually built into a failure point locator. After a short circuit/ground fault is determined based on FIG. 8, the minimum phase of the line-to-line or phase voltage is determined according to the flow shown in FIG. In this way, for the phases determined to be faulty in Figures 8 and 7 (
4) The result obtained by formula is the orientation result. In addition, in equation (1) or equation (4), the term (I^ ・Z) for line voltage drop per unit length is actually a three-phase circuit, and when considering a parallel two-line system, , as shown in Figure 9, is calculated for the faulty phase by taking into account both the fault impedance and the mutual impedance between other lines (own line and adjacent line).For example, in the case of an R phase failure, the following equation is calculated. You are asked to do so.

IA 'Z'IIR'ZIRIR + IIS'
ZIRIS 1IT'ZIRl ding 12 I2-Zl^2^
+I2s゜'I, ^2S+I2T'Z2^2T...
...(7) Next, I^'' in equation (4) has meaning as a vector that is in phase with the fault point voltage V'', as described above, and has the meaning as a polarity quantity.I The simplest way to determine the value of 8" is to use the change in the current of the fault phase, and short circuits are normally determined using the line current. However, regarding ground faults, as shown in the equivalent circuit at the time of 1, li ground fault in Figure 10, the phase current at one end is affected by the zero-sequence circuit shunt, that is, the zero-sequence impedance behind the other end. There is a problem in that, instead of the simple change in fault phase current, the change in α times 11M current of the fault phase is normally used. In the case of the R-phase one-wire ground fault current, the α circuit current is expressed as (I^-Io), which is the form in which the zero-sequence current is removed. Of course, the same phase relationship with ■F is maintained.

Next, how to obtain the polarity amount IA'' will be explained using FIG. 11. I8'' is the change in polarity current between during and before the failure.

In FIG. 11, 21 is the point of failure occurrence, and 22 is the failure detection element (for example, the above-mentioned UV-ZA, tJV-Z OCG
) is the operating point. At time point 22, data prior to the failure detection relay operation time is defined as pre-failure data. The subsequent data can be considered as failure data. In practice, for example, at point 22. Generally, the period before 2 to 4 cycles is considered to be before failure, and the period after 1 cycle is considered to be in failure. The current at data point m during failure is IA
If n is the point in time before the integer multiple cycles of m in the range before the accident, then I8'' is calculated as follows: I^ = IAjI - IAJ1...
...As can be seen from equations (8) and (7), the influence of the power flow superimposed on the fault current is canceled. This ■
^'' is determined at each sampling timing, and Equation (4) is calculated each time.

Overall, from the above, the fault point location calculation in the case of a ground fault is executed by the process shown in FIG.

10 is the α circuit change current of the faulty phase. 2a, 2b,
2c is the voltage data of each phase that is also stored in the memory, 3 is a faulty phase selection section based on the above-mentioned FIGS. 8 and 7, and 4b is a process for switching the phase of the voltage data according to the faulty phase selection result 3. Note that this switching function 4b is actually a software process and is not mechanical. Also, 9 is the calculation part of equation (4). Note that I in equation (4) or orientation calculation block 9
^.Z is obtained by equation (7) based on the failure phase discrimination result 3, but this point is omitted in FIG. 12.

In addition, in FIG. 12, arithmetic processing 9 is performed for each phase,
There is essentially no difference even if there is a method of switching the final output of the locating device according to the result of the failure phase determination section 3.

Regarding the short circuit failure, since it is not related to the gist of the present invention, the explanation and block diagram will be omitted.

(Problems to be Solved by the Invention) According to the above-described conventional method, in response to a failure when recirculating a power transmission line that performs single-phase or multi-phase reclosing,
There is a problem that the error becomes large. This point will be explained using FIGS. 13 and 14.

FIG. 13 shows the fault sum current and α circuit current at the time of an R-phase one-line ground fault, with the pre-failure time region being T1, the fault region being T2, and the single-phase recircuit no-voltage time region being 73. Assuming that the time domain during failure after reinsertion is T4, the fault point location calculation in the time domain T, , T2 is the same as that shown in FIG. 11, and accurate calculation is performed. However, for failures during re-starting in time domains T3 and T4, the unbalanced current during disconnection, that is, the α circuit current in domain T3, is seen as the pre-failure current. This unbalanced current is due to the zero-sequence current, as can be seen from the equivalent circuit of one wire break in Figure 14.
This becomes an error current that is not canceled even by the calculation formula (8) for the difference between the current and the current in the failure region T4. As a result, the failure point location calculation result is affected by the zero-sequence current during the wire breakage, resulting in a large error, and there is a drawback that it is difficult to evaluate the error in the location result. Also, in reality, taking this point into consideration,
For failures that occur subsequent to the first failure, the failure point location calculation is normally locked, and in this case, the location calculation results cannot be obtained if the failure occurs at the time of reinsertion.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a fault point locator that enables fault point locating calculations with as small an error as possible even in the event of a fault at the time of re-opening. [Structure of the Invention] (Means for Solving the Problems) The structure for achieving the above object will be explained with reference to FIG.
means (1a, 1b, Ic), and a second means (2a, 2b, 2b,
2c) and the above-mentioned 1. Third (5) detecting a fault and a faulty phase in the power transmission line using the detection data from each of the second means;
and a fourth means (3), a fifth means (4a, 4b) for switching the current and voltage data to the faulty phase according to the determination result of the fourth means when a fault occurs, and using each of the detected data. Sixth means (9) for calculating the distance from the own end to the fault point
), a seventh means (8) for switching the polarity current input to the sixth means, a time-limited operation timer (6) that is activated upon failure detection by the third means, and this time-limited operation timer. A time-limited return timer (7) activated by a timer is provided, and after the set time of the time-limited operation timer and while the time-limited return timer continues to operate, the fault phase current is input to the sixth means for calculating the distance. It was designed so that it can be used by switching.

(Function) When a ground fault occurs, the fifth means (4a, 4b) is controlled according to the result of the fourth means (3) for fault phase discrimination, and the polarity currents 1a, Ib, 1c and phase Voltage 2a.
2b. Make 2c a failure phase. Further, the seventh means (switching unit 8) is controlled to switch the polar current to the phase current after a time T^ after the failure detection relay operation, that is, the failure point location calculation activation 5 is activated.

This state is TB after the activation signal 5 is restored due to failure recovery.
Time is preserved. After this T[1 hour has passed, the seventh means (switching unit 8) returns to its original state. Note that T^ is provided for coordination with polarity current selection for the first failure.
It is sufficient to cover the time required to complete data collection for the first orientation calculation, for example, about 200 ns. Needless to say, consideration must be given to ensure that the output of No. 5 continues to operate for T^ or more.

Further, 18 is a timer for maintaining that each phase current is used as the polarity amount after switching the polarity amount by T^, and for example, about 5 seconds is enough to cover high-speed restart.

(Example) Examples will be described below with reference to the drawings.

Figure 2 is a block diagram of one embodiment of the fault point locator according to the present invention. In FIG. 2, la. 1b and 1c are each phase current at time m, 2a. 2b. 2c is also each phase voltage data at time m, 3 is a ground fault phase selection block, 4a.
4b is the current according to the result of 3. Voltage data 1a,
This function switches between 1b, 1C and 2a, 2b, and 2c, and is actually a software process. 5 is a failure point locator with a built-in failure detection relay (UV-Z, UV-Z
A, OCG, etc.> operating conditions, this is the failure point location calculation start signal. 6 is a timer for time-limited operation, and 7 is a timer for time-limited recovery. 8 is a function to switch the polarity current data used in the orientation calculation block 9, and for a failure that occurs subsequent to the first failure, each phase current 1a, 1b,' lc
is introduced as a polar current. Note that this switching function 8 is also actually a software process. and 10 is m
This is the α circuit change current of the failure phase at the time, and 9 is a calculation unit.

First, when a one-wire ground fault occurs in the system, the fault detection relay activates the orientation calculation activation block 5, and the phase currents 1a, 1b, 1c are adjusted according to the output of the faulty phase selection block 3.
, each phase voltage 2a, 2b, 2c, and each phase α circuit change current 3a, 3b, 3c are switched and controlled. For the first failure, since it is before the limited time operation timer 6 operates, the polarity current for the orientation calculation block is selected by the data switching process 8 as the α circuit change current of the failure phase, and the orientation calculation is performed thereby. . Next, after T8 hours, the data switching process 8 is controlled to switch the polarity current to the fault phase current in preparation for a fault when the circuit is restarted. This state continues for TB time and returns to the original state. In other words, the phase current is selected as the polarity quantity for at least TB time after T8 hours after the start of orientation, and the polarity quantity is the unbalanced load current during the time domain T3 in Fig. 13 in case of a failure when the circuit is restarted. will not be affected by. Instead, it is affected by the power flow superimposed on the fault current, but the error is small compared to the effect of the current in a system unbalanced state, and therefore the fault point location for one-line ground fault when the circuit is restarted. The effect that can be achieved can be obtained.

Incidentally, the same effect can be obtained by receiving and applying a re-route starting signal or a single-phase cutoff signal from a power transmission line protection relay device instead of the orientation starting signal 5 in FIG. Furthermore, the same effect can be achieved by performing all the orientation calculations for each phase and then determining the results of the orientation calculations to the outside according to the fault phase selection results.

[Effects of the Invention] As explained above, according to the present invention, it is possible to locate a fault point for a one-wire ground fault during reclosing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the location processing according to the present invention, FIG. 2 is an example of application of FIG. 1, FIG. 3 is an example of installation of a fault point locator, FIG. Figure 5 is an explanatory diagram of a failure in a single-end power supply system, Figure 6 is an explanatory diagram of a failure in a double-end power supply system, Figure 7 is a flow diagram explaining a fault phase selection method, Figure 8 is a list diagram of failure selection, and Figure 9 is a diagram explaining a failure phase selection method. The figure is an expanded view of Fig. 3 on a three-phase circuit, and Fig. 10 shows the symmetrical F at the time of a one-wire ground fault.
i standard equivalent circuit, Figure 11 is a processing diagram for determining polarity current, Figure 12 is a block diagram of the location calculation for a conventional one-wire ground fault, and Figure 13 is the polarity current time at a one-wire ground fault. Figure 14 shows the 1-line yfr! This is an equivalent circuit using the α-βO method at 1:00. R-phase current at time 1a...m S-phase current at time 1b...m T-phase current at time 1C...m R-phase voltage at time 2a...m S-phase voltage at time 2b...m 2c...↑Phase voltage 3 at time point 3... Earth fault fault phase determination block 4a... Polarity current data phase switching process 4b... Phase voltage data switching process 5... Orientation calculation starting block 6...・Time-limited operation timer 7...Time-limited return timer 8
...Polarity current data switching 9...Orientation calculation block

Claims (1)

[Claims] A first means for determining the current flowing in the own-end transmission line, a second means for determining the own-end bus voltage or the transmission line voltage, and detection data from each of the first and second means are used to calculate the current flowing in the transmission line. third and fourth means for detecting a fault and a faulty phase; a fifth means for switching the current and voltage data to the faulty phase according to the determination result of the fourth means when a fault occurs; and using each of the detected data. a sixth means for calculating the distance from the self-end to the fault point; a seventh means for switching the polarity current input to the sixth means; and a seventh means activated by the fault detection by the third means. a time-limited operation timer and a time-limited return timer activated by the time-limited operation timer; A fault point locator is characterized in that it is used by switching the fault phase current.