JPH03214075A - Fault point locating device for power system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fault point locating device applied to an electric power transmission system.

[Prior Art] FIG. 3 is a configuration diagram showing a conventional accident point locating device disclosed in Japanese Patent Application Laid-Open No. 61-110067. In the figure, (1) is a parallel two-line power transmission system, (2) is a bus line, (3) is an analog filter in the failure point locating device, (4) is a sample hold circuit that holds data, (5) is a multiplexer circuit that manually switches channels, and (6) is an analog
Digital conversion circuit, (7) is an arithmetic circuit that uses manual data to locate the fault point, (8) is a current transformer for measuring current, and (9) is a voltage transformer for measuring bus voltage. It is.

Next, the conventional technology will be explained. When an accident occurs in the power transmission system (1), the current and voltage at that time are taken in through the current transformer (8) and voltage transformer (9), respectively, and the DC and harmonic components are removed using the analog filter (3). The fundamental wave is held in a sample and hold circuit (4) at regular intervals, and the channels of the multiplexer (5) are sequentially switched. Then, the analog quantity sampled and held by the sample and hold circuit (4) is converted into the analog quantity sampled and held by the analog/digital conversion circuit (6).
) is converted into a digital quantity, and the distance to the accident point is determined by the arithmetic unit (7) using the method described below.

The reason behind the introduction of the accident point location device is that when an accident occurs in the power transmission system, it is necessary to check whether there are any abnormalities in the equipment at the location where the accident occurred and determine whether it is okay to restart or continue power transmission. However, since the power transmission system spans from several kilometers to more than 10 kilometers and often passes through mountains, there was a need for a support device that would allow inspection and patrol personnel to efficiently reach the accident point.

The method for locating the fault point is the shunt ratio method, which applies the fact that the shunt ratio between the fault current flowing in the fault line of the parallel line and the fault current flowing around the healthy line is inversely proportional to the line impedance of each current path. There is an impedance method that applies Ohm's law, which states that the line voltage drop up to the fault point is the product of line impedance and current.

In addition, as mentioned above, there are methods that apply surges or pulses and apply the propagation time of reflected waves at the fault point as a method that does not take in current etc. from the power transmission system.

The conventional method using the shunt ratio calculates the zero-sequence current at the time of the fault, so it can handle simple ground faults, and for short M faults, it is used in combination with impedance calculation applying Ohm's law. FIG. 4 shows the calculation principle of the shunt ratio h' formula among the conventional methods, and the calculation principle of the impedance method as the fifth factor.

In FIG. 4, the principle of the shunt ratio method is that zero-sequence impedance of line ab: zero-sequence impedance of line acb zero-sequence current I0 flowing through calculation path acb. : Zero-sequence current flowing through line ab■. According to the inversely proportional relationship 2, as shown in No. 41J, an accident occurs at a ratio of X to the total length 1.

Zero-sequence impedance of line ab Z-X-Z, (however, Z
, is the zero-sequence impedance of the entire line length), then X4o1o
+ = (2-X)4o1oz, i.e. 102 ” IO++ 102 ”””””””””””)
Referring to Figure 5, the power and impedance method is as follows: Voltage at a terminal = line voltage drop of fault phase 10 Mutual induced voltage from healthy phases in the circuit + mutual induced voltage from adjacent lines + remaining voltage of fault phase = terminal・Fault impedance between fault points * Phase current of fault phase + intra-line mutual impedance between terminals and fault point Sum of healthy phase currents within the main line + inter-line mutual impedance between terminals and fault point Phase current of main adjacent line Total sum + fault phase residual voltage, that is, fault phase; in the case of A phase, VA = X-Z! l fist fA +x-1. ．． Book (Ia” [c) + X4. *(IA” medium h
゛ ◆ tc ′ ) ■ 10 V, A---= =-= ・-・・・(2) By the way, it is generally known that in an accident in a power transmission system, the fault point resistance is the resistance component. Therefore, the remaining voltage at the fault point is only the component in the resistance direction.

Here, if we take the component projected in the direction perpendicular to the resistance direction of equation (2), that is, in the actance direction, v2 will no longer be included in the projected component, and the ratio X up to the accident point will be found as follows.

In addition, in case of a serious accident involving ¥J, VB-X4s*I*”X4m
"(lx" Ic) "X"Z@'"CIA'"
lb'"Ic')" Vra and the above vA above A-V
a-X' (Zs-Zs) ” (lA-1a) ”V
If the actance components on both sides of FA-VFR are taken, VFA-VPB will no longer be included in the projection component, and the following calculation formula for short-circuit impedance location can be found.

vA-V.

' = (Zg-Z-), (Ia-Im) "'
”” ”” ”” ”” ”” (4) The distance to the accident point can be obtained by multiplying X obtained by any of the above methods by the total length of the track.

Hereinafter, the calculation flow of the conventional method will be explained with reference to FIG.

(+61) is a step of measuring the voltage and current at the own end.

(+62) is a step in which occurrence of an accident is detected by voltage drop relay/distance relay calculation, etc.

(+63) is a step in which the accident aspect (distinguishing between short circuit and ground fault, identifying the accident phase) is determined by the operation phase of relay calculation, etc.

(164) is a step of performing short circuit impedance location when it is determined that the accident is two or more phases.

(+65) is a step in which the operational status of the adjacent line is determined based on circuit breaker/switch information, etc., and whether or not two parallel lines are in operation is determined.

(166) is a one-phase ground fault and two parallel circuits are operated, so it is a step to perform zero-sequence difference current location.

(+67) is a single-line operation due to an l-phase ground fault, so it is necessary to carry out ground fault impedance location.

(+50) is a step in which the orientation value is examined to see if it is a value within the section and does not contradict the detection of an accident within the section.

(151) is a step in which, if the orientation value is appropriate, the orientation result is outputted, such as by display or printing on a printer, and if it is inappropriate, the orientation result is rejected.

[Problem to be solved by the invention] In power transmission systems, there are many multi-terminal systems with branch systems.Whether using the zero-sequence current shunting method or the impedance method, in the event of an accident beyond a branch point, an accident on main line F or on a branch line can be detected. It was impossible to determine whether this was an accident based solely on orientation from one end.

Furthermore, in impedance location, if there is a branch on the way, if the current cannot be measured, the line voltage drop cannot be calculated correctly, resulting in poor location accuracy.

Therefore, in order to identify the fault point in a multi-terminal system, it is necessary to measure at each terminal, locate from each terminal, and make a comprehensive judgment by combining multiple location values. However, this requires a location device (or at least a current/voltage measurement and analog/digital conversion device), a transmission device, and a transmission path such as a micro line between each terminal. The cost will be extremely high.

Also, among the conventional methods, the zero-sequence current shunt method: 11.
-IA+1. ◆ [From C^, it can be used in ground fault accidents where the fault points of B and G phases are the same, but there are problems such as it cannot be used in case of multiple faults at different locations where there are multiple fault points.

The present invention was made in order to solve the above-mentioned problems, and it is necessary to newly install a transmission device, a transmission line, a measurement device for each terminal, etc. for a fault point locating device even in a multi-terminal power transmission system. The purpose of the present invention is to obtain an accident point locating device that is highly accurate and capable of locating each accident point in the case of multiple multiple accidents, even without using self-end determination.

[Means for Solving the Problems] The accident point locating device according to the present invention reduces the conventional calculation of differential current location for two-terminal systems by reducing a multi-terminal 'f-system to an equivalent two-terminal system by impedance composition. This made it possible for the formula to be used.

[Operation] In the present invention, the fault point for each phase is determined using the phase difference current locating method using an equivalent two-terminal system that is a contraction of the multi-terminal system.

The fact that the fault current is divided in inverse proportion to the impedance up to the fault point in the two lines is the same for both the zero-sequence current and each phase current. This is a form in which the zero-sequence current in the calculation formula for zero-sequence difference current location shown in the explanation of the method is replaced with the fault phase current. For example, if the accident in Figure 7 is an 8-phase accident, (1)
By substituting the ^-phase current in place of the zero-phase current in the equation, the ^-phase fault point can be found, and by substituting the B-phase current, the B-phase fault point can be found.

In the case of ＾ phase, fault boiling distance = ×・1 (However, 1 = line length of 2-terminal system) ΔIAI: Change in ＾ phase current of IL (fault current) ΔI
A2:2L n [Embodiment of the Invention] FIG. 1 shows an embodiment in which the present device is applied to a parallel two-line M-terminal power transmission system, and (1) to (9) are the same as before. However, conventional fault point locating devices are installed for each line, and in many cases only the zero-sequence current is taken in for the current of the adjacent line, but in the present invention, since each phase current is located, the current of both lines is taken in and the current of both lines is taken in. It can be processed in line-batch.

Next, the calculation flow of each phase difference current locating method of self-end judgment type using system reduction will be explained along the flowchart of FIG.

In (141), all equivalent two-terminal systems are calculated in advance using the set values of the line constants, assuming that the accident point is on the main line and on each branch line.

This will be explained in terms of 1L with reference to FIG. The line length between end -fNi and branch point Tl1 (or T2i3 is Ii, branch point Tl
The line length between i and branch point TI (i◆1) is ll (i◆l)
shall be. Since line impedance and line length are proportional, impedance composition will be expressed using line length below.

First, when contracting the system assuming that there is an accident between the No end (own end) and the branch point Tl1, it is sufficient to contract the system beyond the branch points Tll and T21, so the line between N(M◆I) and 711 The lines between and NM-711 are combined in parallel when viewed from the No end.

This composite line and the line between TI (M-1) and 711 are combined in series when viewed from the No end. If this is repeated until parallel synthesis with the N1-Tl1 line, the Tll-N(M◆1) system is reduced to one line having a line length (line impedance) of LTI1, N(M◆1).

Similarly, if it is assumed that there is a fault point on the Ni-Tl1 line, the Ni-Tl1 line is left as is and the remaining system is reduced to one line.

If the fault point is on the TI-TI(i+1) line, the No-Tl1 system on the left and the TI(i+1)-N(M+1) same system on the right are reduced as shown in Figure 8. Then, they can be attached to both sides of the line between Tl1 and TI (i◆1). In this case, line length LNO-7th ◆11・(i+I
)◆LTI (i+ll N(M*11) 2-terminal system.

(+42) is a step in which the current and voltage at the own end are taken in via the current transformer (8) and the transformer (9).

(+4:l) means that the accident point locating device receives an accident detection signal from the protective relay device, or performs distance relay calculation or voltage shortage within the accident point locating device in order to minimize modification of the existing protective I# electrical device. This step is to perform accident detection calculations using the principle of relays, etc.

(+44) is a step of freezing the voltage and current data of the own end in the memory when an accident is detected.

(+45) is a step of determining which phase of which line has a fault based on the current change (-1 current during fault - current before fault).

(+46) is used to determine the approximate location of the accident point.
For accidents involving 2 phases or more, short circuit impedance should be determined.
This is a step to perform ground fault impedance location for an l-phase ground fault.

(+47) applies each phase difference current locating method to the fault phase. Starting with the calculation formula where the accident point is on the track between No.-Tl1, after examining (147), next
As shown in the calculation formula in Tll, orientation and orientation value examination are repeated in sequence.

When substituting the difference current between line 1 and line 2, if the equation has its own end NO subjected to system reduction, the difference current should be reduced as shown below, converted to the vS system equivalent, and then substituted. do.

Also, after the orientation distance is obtained from the equivalent two terminals, it is necessary to return the contracted system to its original length, so (Equation 5) is @ff1.□＞ −−−−−−・・・・−−−
--(7).

(148) is a step of examining the orientation value corresponding to each accident point. For example, assuming an accident on the track between No-Tl1, the orientation result using the equation is the track length l between No-Tl1.
When it is larger than N0-Tll, this orientation value is rejected as the assumption of the accident point is incorrect.

In addition, the location result using the calculation formula assuming an accident on the Tl1-TI(i+1) quantity line is LNI)-Tl +"1Ti-T(i+
1). ), it is assumed that the assumption of the accident point was incorrect, and orientation is continued using a calculation formula in which the accident point is farther away.

Even if the accident section is narrowed down in this way, Tlk-TI(k
◆1) The branch line Nk-, which is one branch line before, is located beyond the intermediate line.
It is not possible to determine whether the line is on the Tlk line or not. In this case, compare it with the ground fault or the estimated value obtained by shortened impedance location, and if it is smaller than the location value determined by impedance calculation, or if the difference is at least 5 or more, reject the fault point (location value). do. This is because in impedance locating, the power flow is shunted to a branch load on the way, and the current added to the subsequent line voltage drop becomes smaller.

The current measured at the end used for impedance locating includes the value of the shunt valve to the branch load, and the calculation formula is satisfied assuming that the current of the accident black blood value is flowing. (indicates the tendency to orient to

Therefore, the location value for impedance location, which can only be determined approximately by the ψ value, is used to filter out the location values for each phase difference current location.

(+49) is a step of applying the previous equivalent two-terminal system and determining whether the previous fault point has been checked.

(150) is a step in which the orientation value is examined to see if it is a value within the section and does not contradict the detection of an accident within the section.

Step (151) is a step in which, if the orientation value is appropriate, the orientation result is outputted by display or printing on a printer, and if it is inappropriate, the orientation result is rejected.

In addition, in the above example, the branch line was explained as a system with two parallel lines, but if one line is branched or one line of two parallel lines is stopped.
It can also be applied to systems that operate on line power reception. This is because in either case, in the calculation formula for operating two parallel lines, the current in the line that is not in use is 0, and there is no problem.

[Effects of the Invention] The present invention reduces a parallel two-line multi-terminal system to an equivalent two-terminal system by impedance synthesis, making it possible to apply the conventional self-end discrimination type differential current location method for two-terminal systems. This eliminates the need to newly install a transmission device/transmission line dedicated to the accident point locating device and a measuring device for each terminal, making it possible to provide an inexpensive device.

In addition, in the case of an accident occurring far from a branch point in a multi-terminal system, even though a location value can be obtained by locating using only own-end information, it is necessary to identify whether the accident point indicated by the distance is on the main line or a branch line. The problem is that it was impossible to do so in the past, or that the system beyond the junction was reduced to an equivalent two-terminal system because the accident point was before the junction, or when the accident point was on the main line beyond the junction. One is a system in which the rest of the system is reduced to an equivalent two-terminal system by contracting everything other than the lines, the other is a system in which the fault point is at a branch line and the remaining system is reduced to an equivalent two-terminal system, and the system is reduced to an equivalent two-terminal system with all fault points at the fault point. By doing this for each case and locating each contracted system, it is possible to limit the accident point to about two force points, and one of them indicates the correct accident point. This will greatly improve the efficiency of patrols and inspections after an accident.

Furthermore, by using the external phase current, it is possible to separately locate each fault point even in the case of a multi-point leisure accident where the fault point of one phase is different from the fault point of another phase.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the present invention applied to a parallel two-line M-terminal power transmission system, Fig. 2 is a flowchart of the fault point locating method of the present invention, and Fig. 3 is a conventional device applied to a parallel two-line two-terminal power transmission system. Figure 4 is a diagram explaining the principle of zero-phase difference current location, Figure 5 is a diagram explaining the principle of impedance location, Figure 6 is a flowchart of the conventional fault point location method, Figures 7 and 8 are is an explanatory diagram of system reduction. In the figure, (1) is a parallel two-line power transmission system, (2) is a current transformer, (3) is an analog filter, (4) is a sample-and-hold circuit, (5) is a multiplexer circuit, and (6) is a sample-and-hold circuit.
) is an analog-to-digital conversion circuit, (7) is an arithmetic circuit,
(8) is a current transformer, and (9) is a voltage transformer for measuring JiJ II voltage. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] For locating fault points in multi-terminal power transmission systems,
Multi-terminal power transmission system is equivalent to 2 by impedance synthesis.
A fault point locating device for a power system, which is reduced to a terminal system and locates a fault point by a phase difference current locating method using each phase current introduced.