JPH02223331A - Accident phase detection device - Google Patents

Abstract

PURPOSE:To select an accident phase accurately in multiple accidents extending over two circuits by discriminating the accident phase in a transmission line accident with an operation section and a decision section on the basis of the value of the fault current that flows to the transmission line. CONSTITUTION:An accident phase selection device is equipped with an operation section 11 and a decision section 12. The operation section 11 is composed of the 1st operation section 111 finding the differential current of the currents before and after the accident, the 2nd operation section 112 operating the ratio of line currents in two-circuit sum current, the 3rd operation section 113 operating the ratio between the maximum value and minimum value of each phase current in two-circuit sum current, the 4th operation section 114 operating in comparison the volume of two-circuit each-phase current with respect to the accident phase and the 5th operation section 115 operating the ratio of line currents in a self-circuit. An accident circuit and an accident phase are detected by the output from accident phase number detection sections 121 to 124 in a two-circuit accident and the output of detection sections 125 to 127 to detect the accident circuit side of the two circuits. The accident phase can thereby be accurately selected in multiple accidents extending over two circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a fault phase sorting device in the event of multiple faults in a directly grounded power transmission line.

(Prior Art) A fault point locating device is used to determine the distance to a fault point on a power transmission line. In this case, it is necessary to use the voltage and current in the fault phase for distance calculation. Fault point location is then performed using a digital arithmetic processing device as shown in FIG. As shown in the figure, the voltage and current of the power system are taken in through the input converter 41 that centralizes and houses the auxiliary PCT, and a filter (FL) extracts only the commercial frequency components of the voltage and current. Filtering is performed at 41. Since each filter output is an analog signal, it is inputted to an analog/digital converter (^/D) 45 via a sample hold circuit (S/H) 43 and a multiplexer (MPX) 44, and converted into a digital signal. . The digital signals of voltage and current converted here are temporarily stored in a data memory (RAM) 47 via a direct memory access (DMA) 46.

CPU 48 is the current stored in IIAH47.

Reference numeral 50 denotes an input/output device which digitally processes the voltage data according to a processing procedure stored in a read-only memory (ROM) 49 and performs orientation start-up and orientation calculations.

The location methods can be roughly divided into the following two methods.The first method does not select the fault phase, but uses voltage and current to calculate the distance in the case of a ground fault fault, and the distance calculation in the case of a short circuit fault. This method calculates the distance to the accident point by performing the following steps.

The second method uses an undervoltage relay with current compensation (a type of distance relay) to perform fault phase selection, and then calculates the distance to the fault point.

Alternatively, there is a method in which accident phase selection is performed as shown in Japanese Patent Laid-Open No. 63-217917, and then the distance to the accident point is determined.

(Problems to be Solved by the Invention) Directly grounded power transmission lines generally have two parallel circuit configurations to ensure a stable supply of electric power. For this reason, accidents may occur on two lines at the same time. However, although the above-mentioned conventional method can accurately measure the distance when a fault occurs on a single line, it has the disadvantage that when multiple faults occur across two lines, it becomes difficult to identify the fault phase of the fault line, and the distance to the fault point becomes inaccurate. .

The present invention has been made to solve the above problems, and is a fault phase selection system that can quickly and reliably select fault phases using only current even in the event of multiple faults spanning two circuits in a directly grounded system. The purpose is to provide equipment.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides the following means based on the value of fault current flowing through the power transmission line, so that the It was configured to determine the

■Each phase current for each line based on the difference current before and after the accident.

Difference current calculation means 11゜ which calculates each phase sum current of each line current 9 and each line sum current of both lines. If the ratio obtained by the calculation means and the first calculation means is smaller than a predetermined value, it is considered a one-line ground fault fault in two lines, and if all three interline phases are larger than the predetermined value, it is considered a two-line ground fault. A first determining means 121, 122°■ for determining a fault in two or more lines; a second calculating means for calculating the ratio of the maximum value and minimum value of each phase current in the two lines; If the ratio obtained by the means is smaller than a predetermined value, it is determined to be a two-phase or less fault in two lines, and if it is larger than the predetermined value, it is determined to be a three-phase fault in two lines. a third calculation means that calculates the ratio between the difference between the fault currents of each phase of the two lines and the own line fault current, and when the ratio obtained by the third calculation means is smaller than a predetermined value for all fault phases; If the fault is greater than a predetermined value for one fault phase, it is determined to be a fault in one phase of the own line, and if two or more fault phases are larger than a predetermined value, it is determined to be a fault in two or more phases of the own line. 3 determining means 125 , 126 , 12
7゜(Function) First, in the difference current calculation means 111, each phase current (I) for each line is calculated from the difference current before and after the accident (fault portion current),
Find the difference current between each line (CIA), the sum of each phase current of both lines (■), and the sum of each line current input (I) of one and both lines.

Δ■ The first calculation means 112 uses each line current I obtained by the above-mentioned difference current calculation means to calculate the ratio of this maximum value ΔD and each line current. If this ratio is smaller than a certain constant value (K1), the 1-phase fault detection unit 121 in the first determination means determines that a 1-line ground fault fault has occurred in 2 lines, and all 3 inter-line phases are detected. If it is larger than a certain value (K1), the two-phase fault detection unit 122 in the first determination means
This is considered an accident involving two or more lines. Also, the second calculation means 1
In step 13, find the ratio (X,) between the maximum value and the minimum value of each phase current in the two lines, and find the constant value (KF) that this ratio corresponds to.
If it is smaller than 2, the determining unit 123 in the second determining means
If the fault is greater than a certain value (K,), the determining unit 124 in the second determining means determines that it is a three-phase fault in two lines.

Furthermore, the third calculating means 114 focuses on the fault phase of the two transmission lines, and calculates the ratio of the difference between the phase change currents of the two transmission lines and the fault current (I) of the own line. A constant value (Kd) that this ratio holds for all accident phases
If it is smaller, the determining unit 125 in the third determining means determines that the adjacent line is a fault, and a constant value (K,
), if the determination unit 1 in the third determination means is larger than
26, it is assumed that one party in the own line is at fault, and if the fault is greater than a certain value (K,) for two or more fault phases, the determination unit 127 in the third judgment means determines that there is an accident in two or more phases of the own line. judge.

Note that the calculation means 115 in the calculation section 11 is a fault phase detection means in the case of a two-circuit power transmission line.

Therefore, the fault phase number detection unit 121゜12 in a two-line fault
A detection unit 125 that detects the faulty line of the two lines by focusing on the outputs from 2, 123, and 124 and the fault phase.
, 126, and 127 make it possible to detect fault lines and fault phases.

(Example) First, in a directly grounded parallel two-circuit power transmission line, when focusing on the sum current of each phase of the two lines at the time of a system fault, the following phenomenon occurs.

In the event of a single-wire ground fault, the fault current concentrates on the faulty phase and does not flow to the healthy phase, so the converted current of the healthy lines in the same phase becomes zero.For example, taking an A-phase single-wire ground fault as an example, The amount of current change in each phase is (1), □=I, Ib□=IC1=0. Therefore, the change in each line current is: 1 1=lI 1=lIl, II 1=Oa
bT caT bcT. That is, it can be seen that the ratio of the maximum phase of the change in the line current to the value of each line current differs greatly from that in the case where only the normal lines are in phase. Here, if the ab phase and the ca phase are IPU, the bc phase is opu. In addition, in the event of a fault involving two or more lines, the amount of change in current between each line will be approximately 50% or more compared to the maximum value. For example, in the case of a short circuit between two wires of the bc phase, the current of each phase is: ■a■=0. Ib■=-ICd=I The current between each line is II I=lI 1=lI+.

abT caT II I=211 bcT, and each line current is 1/2 of the maximum line phase current.
becomes. That is, if the bc phase is IPU, the ab phase=ca phase=1/2PU. To summarize the above, when a system fault occurs in a directly grounded system, the fault current (change current) is as shown in Table 1 according to the fault type.

Table 1 (1');I'-1', I
'-1'.

bT abbc 1'i' a 1'l', I' ・Each phase change current = [1'] aT
l bT aTl (1') ;I:I'U] bT 1laX a, b, c; It can be seen that it is possible to distinguish between a single-wire ground fault accident and an accident involving two or more wires.

Multi-f that spans two lines again! In the case of a fault, the fault current for each phase of both lines is larger in the fault line, so the value obtained by dividing the difference between the phase currents of both lines by the own line phase current is as shown in Table 2.

Table 2 provides that: I: Current input for own line fault 1 ■ = Current input for adjacent line fault 2 It can be seen from Table 2 that if the above detection is performed, it is possible to identify the faulty line in the event of a two-line multiple fault.

FIG. 1 is a functional block diagram of an embodiment of the accident phase sorting device according to the present invention. 10 in Figure 1
is a fault phase sorting device, which includes a calculation section 11 and a determination section 12, and the calculation section 11 includes a first circuit that calculates the difference current between the currents before and after the accident.
A calculation unit 111, a second calculation unit 112 that calculates the ratio of the line current in the two-line sum current, a third calculation unit that calculates the ratio of the maximum value and minimum value of each phase current in the two-line sum current. Part 113.
A fourth calculation unit 114 that compares and calculates the magnitude of each phase current of the two circuits for the fault phase. A fifth calculation unit 115 that calculates the ratio of line currents of own lines, and a one-phase fault detection unit 12 in two lines
1° 2-phase or more fault detection unit 122, 2-phase or less fault detection unit 123, 2-line 3-phase fault detection unit 124. Adjacent line accident detection unit 125. Own line 1 phase fault detection unit 126. It is composed of an own line 2-phase or more fault detection section 127, a 1-phase fault detection section 128 for one line fault, and a 2-phase or more fault detection section 129.

In addition, (work) is each phase current of each line, (IA) is each line current, and (I) is each phase sum current of both lines.

person■ (I> is the sum of current between each line of both lines.

Δ■ FIG. 2 is a flowchart illustrating the phase selection operation, and in this case only the accident phase selection is shown. When a system fault occurs, the pre-fault current is immediately memorized, and fault phase selection is performed using the judgment formula described below.

First, in step S21, the changed current obtained by subtracting the stored pre-failure power flow of the two lines from the current at the time of the fault is calculated as the sum of each phase current f' for the two lines, 1, its interline current ■', and each phase current for each line. Min1', ”, t2, own rotation Δ■
Person 1 Calculate each of the line-to-line currents. Note that the symbol with a dash ′ indicates a changed current.

Step S22 is a selection process for determining whether or not the two line systems operate in parallel. In this case, it may be set in advance during two-line operation, or the mutual inductance (ZH) may be set and determined. If the two lines are in parallel line operation, in step S23, the maximum sum [I'] and the minimum sum of the phase currents of the two lines are determined.
1a × [I'] ・And the sum of the currents of each phase of the two lines is the line-to-line conductor T
Determine the maximum nun current [I']. SΔT
Find nax. In step S26, each phase current f' of each line,
I” is larger than 1 person 2. In step 5241, it is determined whether or not Xl is larger than KT. If Xl<K, in step 5291, it is determined that there is a phase l fault in the [1'] phase in 2 lines. Department T l
aX Do. If XT≧, then in step 5251
It is determined whether or not r is greater than Kr, and if X'KF, then in step 5292 a two-phase fault related to the [I'] phase is determined in two lines.

If ΔT nax Stellar 75261 determines whether or not Y is greater than Kd for the fault phase, and if YAK, it is determined in step 8305 that there is an adjacent line fault. Y
If ≧Kd, it is determined in step 5262 whether there are two or more phases of (Y>K,), and if there are two or more phases of (CY>K,), in step 3304 the two lines of the own line are determined. If the above accident is assumed and the phase of [Y>Kd) is one phase, step 3
In step 303, it is determined that there is a ground fault in one line of the own line.

If it is determined in step S22 that the two-line operation is not performed, the maximum line-to-line current [1'] of the own line is determined in step 327. In step ΔlaX step 5281, it is determined whether or not X is smaller than K. If It is determined that the accident involved two or more lines. And the judgment conditions are as follows.

Here, 1 and K are, for example, 0.2 to 0.3.

Also [1') , (1') ・
are respectively ΔT l1nn Δ
This is the smallest of l1In(1') and (1'Y).

Δ■ Then, equations (1) and (4) hold true in the case of a one-wire ground fault (including faults in the same phase) for two circuits in total, and 2
This does not hold true in the case of an accident involving more than one phase. KF and KF are used to identify whether or not it is a three-phase fault, and are values that take into account the unbalanced currents in each phase that occur in the event of a three-phase fault.

For example, it is set to 0.6 to 0.8. K, for example -
0.15 to -0.3. [1'yo,] is 1 of own line
The tIA current is [1'), and 2] is the @ current of the adjacent line.

If there is a fault in a certain phase of the own line and there is no fault in that phase of the adjacent line, (1'), 1) >CI', 2), and Y>O. If there is an accident on the same phase on both lines, the accident at the same time is [■'] medium (1' yo 2), and Y > 0 and person 1. There is no accident on the own line and there is an accident on the adjacent line. In case,
(I') <[1'. ], and Y<O and person 1.

In this way, if there is an accident on the own line, Y>0, and if there is no accident, Y<O. However, the judgment value is given a margin in consideration of variations in the inductance of both lines in the event of an accident at the opposite end and the nearest end, errors in the equipment, etc. This is not a problem because even if it is determined that the fault is a fault on the own line when it is not a fault on the own line, the orientation value of the fault point exceeds the length between the own lines and the fault is rejected.
This is because if it is determined that it is not an own-line accident and the location is not determined even though it is an own-line accident, it will be a fatal problem.

Equations (1) and (4) hold true in the case of a single-wire ground fault, and in this case, the fault phase is [■'] 1
It becomes aX. [I'] is the largest person of (1'), 18X. Also, the accident phase is [1'], which is related to Δ
The same result can be obtained even if the phase does not contain l1In.

Equations (5) and (6) hold true in the case of an accident involving two or more lines, and the accident phase is (1'A,) is the maximum phase of [1'Y].

As a method for identifying the faulty line described in equation (3), the fault phase may be given by the following equation.

Here, Kdl is set to, for example, 1.1 to 1.5. Equation (7) is (1') >CI' if only the own line has an accident.
yo, [person 1] and Yl〉1, and if there is an accident on both lines, [1']
middle (1' yo 2), Y1 middle 1, own line 1 If there is no accident on the line and there is an accident on the adjacent line, (1'
) <(1', ).

Person 1 FIG. 3 is a flowchart illustrating the operation when a fault phase is detected by the fault phase detection device and this is applied to failure point location. Step 831 in FIG.
The process from S34 to S34 is the same as the above-mentioned accident phase selection. If the accident phase is determined in step 834, step S
35 and subsequent fault point location calculations (conventionally known) are performed.

[Effects of the Invention] As explained above, according to the present invention, it is possible to accurately classify fault phases, not only in the case of an accident in one line, but also in the case of multiple faults spanning two lines in the case of two parallel lines. It is also possible to locate fault points with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of an embodiment for explaining the fault phase sorting device according to the present invention, FIG. 2 is a flowchart for explaining phase sorting operation, and FIG. 3 is an example of a flowchart for locating a fault point. FIG. 4 is a diagram showing an example of the configuration of a failure point locating device using a microcomputer. 10... Accident phase sorting device 11... Arithmetic unit 12.
・Discrimination part

Claims (1)

[Scope of Claims] A fault phase sorting device characterized by comprising the following means to determine the fault phase at the time of a power transmission line fault based on the fault current value flowing through the power transmission line. (1) Difference current calculation means for calculating each phase current of each line, each line current, each phase sum current of both lines, and each line sum current of both lines from the difference current before and after the accident. (2) a first calculation means that uses each line current to calculate the ratio between this maximum value and each line current; and if the ratio calculated by the first calculation means is smaller than a predetermined value, A first determining means that determines a one-line ground fault fault and determines a two-wire or more fault in two lines when all three inter-line phases are larger than a predetermined value. (3) a second calculating means for calculating the ratio between the maximum value and the minimum value of each phase current in the two lines; and when the ratio calculated by the second calculating means is smaller than a predetermined value, 2-phase or less, and if it is larger than the specified value, a 3-phase accident on 2 lines
A second determining means for determining a mutual accident. (4) a third calculating means for calculating the ratio between the difference between the fault currents of each phase of the two lines and the own line fault current, and the ratio obtained by the third calculating means is set to a predetermined value for all fault phases; If it is smaller than the specified value, it is considered an adjacent line fault; if one fault phase is larger than a predetermined value, it is considered a one-phase fault in the own line, and if two or more fault phases are larger than the predetermined value, it is considered a fault in two or more phases of the own line. Third determining means for determining.