JP3053119B2 - Accident aspect identification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a fault locating function of a transmission line, which is useful information for maintenance and operation of a power system.

[0002]

2. Description of the Related Art A well-known example of the prior art relating to the present invention is disclosed in Electric Cooperative Research Vol. 41, No. 4 digital relay 1
Although the high-precision fault point location is described on pages 84 to 185, the specific contents of the line constant used for the location calculation are unknown.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an accident mode identification device which can calculate a distance to an accident point and a resistance at an accident point with high accuracy, particularly in the case of a ground fault. .

[0004]

In order to achieve the above object, the present invention focuses on the shunt ratio between the ground and the overhead ground line on the return path of the fault current which has a large effect on the orientation in the event of a ground fault. , And the corrected line constant is used.

[0005]

According to Kirchhoff's law of an electric circuit using the corrected line constants described above, the distance to the fault point and the resistance at the fault point are calculated with high accuracy.

[0006]

FIG. 1 is an overall explanatory diagram according to the present invention. Hereinafter, the symbols in the figure and their contents will be described.

FIG. 1 illustrates a single-line ground fault in a three-phase AC transmission line, which is represented by a single-line diagram.
In the figure, reference numerals 11 and 12 denote three-phase AC power supplies, and 13 and 14.
Is the neutral ground impedance of the power supply. The neutral point ground impedances 13 and 14 are ideally zero ohm conductors in a direct grounding system, and resistors are installed in a resistive grounding system according to the purpose of limiting the ground fault current, respectively. Is done. In some cases, a reactor is connected. However, since these conditions do not directly affect the implementation of the present invention, the contents of the neutral point impedances 13 and 14 are not particularly limited here.

Reference numeral 20 denotes a transmission line, which is an accident aspect identification target line. The section has a length L (k) between the S terminal and the R terminal.
m). This transmission line may be a single line of three-phase alternating current, two or more parallel lines, or a plurality of such lines, but are shown here by a single line for convenience of description of the present invention. 50
Is an accident aspect identification device, which identifies the position of the accident point, the resistance at the accident point, and the like when an accident occurs in the transmission line 20. The accident situation identification device 50 requires voltage and current signals at both ends of the identification target line 20 as input signals. In this embodiment, the current at the S terminal is IS, and the voltage is V
The current at the S and R terminals is indicated by IR, and the voltage is indicated by VR. Each signal is a vector quantity, and the direction of the arrow in FIG. 21 and 22 are current transformers for receiving current signals IS and IR, respectively, and 23 and 24 are voltage signals V
It is a voltage transformer for taking in S and VR. 31,3
Reference numeral 2 denotes a data collection device, which transmits voltage and current signals of the S terminal and the R terminal to the accident state identification device 50. 3
Numerals 3 and 34 denote data transmission lines, respectively.
A transmission line for transmitting a signal to a computer, such as a microwave line, an optical cable, or a telephone line. F is the accident point, M (km) from S terminal
And the point. RE is the accident point resistance.

The accident mode identification device 50 calculates the distance M (km) to the accident point and the accident point resistance RE according to Kirchhoff's law based on the voltage signal VS and the current signal IR at the S terminal, and outputs and displays the result. .

Next, a specific example of the calculation method will be described. First,
A constraint matrix is created based on the voltage and current signals of each terminal. FIG. 2 shows the three-phase AC parallel two-circuit transmission line shown in FIG. 1 for each phase. In FIG. 2, 1L of Line 1 is indicated by phases No. 1, 2, 3, 2 and 2L of Line 2 is indicated by phases No. 4, 5, 6. The voltage signals V1, V2... V12 at the S terminal and the R terminal, and the current signals I1, I2,
It is displayed so as to correspond to the phase order like I12.
L indicates the line length (km) from the S terminal to the R terminal.
k is the distance to the accident point, with the line length L
Is set to 1 and k = 0 for an S-terminal near-end accident, k = 1 for an R-terminal near-end accident, and k = 0.5 for an accident at an intermediate point. Things. R1, R2,... R6, RE are the fault point resistances of the respective phases, and RE is the common fault point resistance of the fault phases. E1,
E2,..., E12 also relate to the voltage drop of the lines of the respective phases (not shown).

[0011]

(Equation 1)

Here, Z11, Z12,..., Z66 are impedances per 1 km between transmission line phases.
As shown in (1), the impedance matrix is symmetrical between the phases, and here, for simplicity of description, the distribution constant is assumed to be uniform over the length L (km). In Equation 1, the voltage signals V1, V2... V12 and the current signals V1,
V2 ... V12, impedance Z11, Z12 ... Z66
Are complex numbers, and E1, E2... E12 are also plural. When the current flowing through the fault point resistor RE is indicated by IE,
Equation 2 is obtained.

[0013]

(Equation 2)

In FIG. 2, equation 3 holds for the voltage equation of each terminal and each phase.

[0015]

(Equation 3)

Equation 3 includes a complex number, but the unknown is k indicating the position of the fault point, the fault point resistances R1 and R2 of each phase.
... R6, RE, which are scalar quantities. Watanabe L,
Line impedance matrices Z11, Z12 ... Z
Numeral 66 denotes a value specific to the line that specifies the accident condition, which can be input in advance as a set value. L is a scalar quantity, Z11,
Z12 ... Z66 are complex numbers. In addition, the voltages V1 and V
2, V12 is a complex number and is a measured value, currents I1, I2,.
Is also a complex number and a measured value. Since there are eight unknowns, the position k of the fault point and the fault point resistances R1, R2.
Is required. In addition, these values can be calculated for each time section, and the measurement time of the voltage and current values is set to time t,
The unknowns may be set independently of k (t), k1 (t)... KE (t), and all the measured values may be solved as simultaneous equations in the same manner as in Equation 3. Also, it is assumed that the position of the accident point is constant during one accident and that k does not change, and only the accident point resistances R1, R2,... RE may be solved as independent unknowns for each time section. Further, assuming that the average value of the position k (t) of the fault point calculated at each time section is k, k is substituted for the unknown k and the fault point resistances R1 (t), R2 at each time section.
(T)... RE (t) may be recalculated. that's all,
The method of directly solving Equation 3 has been described.

FIG. 4 uses a digital computer.
FIG. 4 is an operation flowchart showing an embodiment of the operation method of the present invention.
In the figure, a step 40 is for setting the system data, and is input as a preset value required for the arithmetic processing, such as the value of the line length L, the line impedance matrices Z11, Z12... Set data that can be set. Step 41 shows an accident detection and data collection step. The fault detection is to detect the occurrence of a fault in the target system of the fault condition identification device. For example, a directional distance relay or a current differential type carrier relay used for a system protection relay may be used. When an accident is detected by the accident detection, each terminal voltage and current signal is transformed into digital data by sampling synchronized with each terminal and collected. At least data is collected from the occurrence of the accident until the accident is cleared. In collecting data at each terminal, depending on the short-circuit capacity of the power system, the neutral point grounding resistor current, etc.
There is also a method of preparing a plurality of data groups in which the level per bit for performing digital conversion is changed for a ground fault having a relatively small fault current and a short-circuit fault having a relatively large fault current. The same applies to the digital conversion of a voltage signal. In step 42, the type of accident is determined, and it is determined whether it is a short circuit accident or a ground fault accident, and is used as information for selecting a use destination of the data collected in step 41. Step 43 shows the data selection process. Data necessary for arithmetic processing is selected from the collected data and taken in according to the accident type determined in the previous step. Step 44 is a line voltage matrix creation process, in which a matrix of voltage equations is created based on the data input through the above steps.

Of course, the data used here is a real part,
Since it is expressed in the imaginary part, a reference vector is set in advance based on the voltage and current signals obtained by sampling synchronized at each terminal, and the real part and imaginary part of each complex signal are set accordingly. To separate. In FIG. 4, the real part and the imaginary part are created in step 41 or step 44.
May be implemented. Step 44 shows an example of creating a matrix at one sampling point, and is an embodiment of a method for obtaining a solution at each one-time cross section. Step 45 is for performing an accident phase discrimination calculation.
The fault phase determining means calculates the sum of the current signals of both terminals for each phase, and when the value exceeds a predetermined determination level Ip, determines that the phase is fault within the section of the length L. I do. This is a fault phase judging method based on a current differential method of a protection relay applying Kirchhoff's first law.
Here, the judgment level Ip is an error at the time of measuring the current signal, a set value for preventing the erroneous judgment from flowing to the charging within the length L section, and other noises. The protection relay may be the same as the variable differential protection relay. Further, the current differential input signal for judging the fault phase may be any one of the discrimination based on the sample value itself, that is, the discrimination based on the instantaneous value, the discrimination in a complex number format, or the discrimination between the real part and the imaginary part. Alternatively, it may be based on the matching condition of the above-described determination method or the OR condition. Further, the level of the current IE flowing through the common resistor RE shown in FIG. 2 is determined to determine whether a ground fault has occurred. The level judgment value of the current IE is also the judgment level I of each of the above phases.
Like p, it is used to prevent erroneous determination. Step 46 is the position k of the accident point, the accident point resistances R1, R2,.
K (t), R1 (t), R2 at time t
(T) is a step of calculating RE (T). In step 46, in accordance with the accident phase discrimination determined in step 45, the term of each of the accident point resistances R1, R2.
After performing valid / invalid processing on the terms of 1, U2... UE, the terms are converted into partial differential equations to obtain unknown numbers. However, if the line is disconnected from the system from the circuit breaker switching state signal, this is excluded from the simultaneous voltage equations. The result calculated in step 46 becomes a solution for each sampling value, and it becomes possible to specify the accident aspect in chronological order. However, it is conceivable that the influence of the measurement error differs for each sample value. For example, it is conceivable that the position k of the fault point occurring in the power system is fixed and only the fault point resistance changes, so it is inconvenient to change the position k of the fault point for each sample value. Therefore, hereinafter, in steps 47 and 48, a correction operation is performed as a second operation step.

In step 47, the average value ka of the position k (t) of the accident point at each sampling time point calculated in step 46 is calculated. After that, it is assumed that the position of the accident point is at the average value ka, and the calculation of step 48 is started. In step 48, the accident point resistances R1 (t), R2 (t)... RE (t) are recalculated at each time of re-stop by making the position k of the accident point known with the average value ka. Step 49 is a step of outputting the operation result described above. Here, the measured voltage, current signal, and calculation result of each terminal are output to a control station, a substation, or a power supply command station that needs the data. In addition, it performs data storage control and the like. As described above, each time the system fault occurs, the calculation flow of FIG. 4 is continued until the fault is cleared.

FIG. 5 shows an embodiment relating to the system configuration of the present invention. This figure shows an example of the system configuration on the S terminal side described in FIG. 1 and serves as a master station for other terminals. In FIG. 5, the same symbols as those in FIG. Hereinafter, the symbols and the operation contents of FIG. 5 will be described. Reference numeral 31 denotes a master station portion of the S terminal system. The master station 31 has, in addition to the signal input section of its own terminal, transmission and reception of signals from other terminals, an accident mode identification calculation function as a central device, and a display function. The contents of the master station system 31 will be further described. 111 is A / D
It is a converter, the voltage and current signal of the S terminal, and the circuit breaker C
The open / close state signal of B is converted into a digital quantity and taken in. A
As described above, the / D converter 111 may have a plurality of configurations in which conversion levels are changed for a short circuit accident or a ground fault accident. Reference numeral 112 denotes an oscillogram, which is used for recording and displaying a signal input by the master station 31. Reference numeral 113 denotes a protection relay device for the transmission lines 1L and 2L, which is used in some cases to share an input signal with the system of the present invention, and to use the judgment result of the protection relay device 113 for an accident situation identification calculation. For example, the judgment result of the protection relay device 113 can be used as an input signal to judge an accident phase, a short circuit, and a ground fault accident.

A memory 114 is used to store input signals, received signal data, transmitted signal data, and the like.
115 is a data processing unit. The data processing unit 115 performs complex number format data conversion on the signal data collected from each terminal, and detects an occurrence of a system failure. Only when a system fault is detected, signals from other terminals are transmitted so that the master station can collect data. Reference numeral 151 denotes a converter for performing signal format conversion, for example, a U / B converter for converting a unipolar format to a bipolar format signal. Reference numeral 152 denotes a B / U converter that performs an inverse conversion of the B / U 151. Reference numeral 153 denotes a signal terminal, which performs channel assignment of a data transmission path. Fifteen
Reference numeral 4 denotes a transport device, which is an interface serving as an interface for performing data transmission with each counter terminal. Reference numeral 511 denotes a computer for performing the accident aspect identification calculation according to the present invention. The computer 511 executes the calculation flow of FIG. Reference numeral 512 denotes an auxiliary computer that outputs a calculation result or monitors the system. Reference numeral 513 denotes a CRT display for displaying a screen. A line printer 514 records data. A data transmission modem 321 connects the master station 31 with a control center or a power supply command center. The modem 321 may be a small-scale device for one channel of the telephone line, for example, when transmitting only the operation result of the master station 31. Reference numeral 322 denotes a transport device, which is an interface for a data transmission system.

FIG. 6 shows an example of a system configuration corresponding to the terminal 32 of the R terminal shown in FIG. The same symbols as those shown in FIG. 1 or FIG. 5 indicate equivalents. 2
Reference numeral 11 denotes an A / D converter, which outputs a voltage and current signal of an R terminal.
5 and converts the open / closed state signal of the circuit breaker CB into a digital quantity and takes it in. This is the same as the A / D converter 111 in FIG. A memory 214 is used to store input signals, received signal data, transmission data, and the like. 21
Reference numeral 5 denotes a data processing unit which performs addressing of transmission and reception data, editing of data, monitoring of data, and the like. It may be the same as the data processing unit 115 in FIG.
251 is a unipolar / bipolar signal converter, U / B
It is a converter.

Reference numeral 252 denotes a bipolar / unipolar signal converter, which is a B / U converter. 253 is a signal terminal. Reference numeral 254 denotes a transport device. Data transmission is performed via the signal terminal 253, the transport device 254, and the transmission line 310 in response to a data transmission request from the S terminal, with the S terminal as a master station.

FIG. 7 shows a terminal system such as a control station or a power supply command station for displaying the calculation result or using the result as system control information. Reference numeral 50 denotes a display and storage device for the output shown in FIG. Reference numeral 321 denotes a signal transmitting / receiving carrier. Since the transport device 321 does not always exist in the same building or in the same room as the output display and storage device 50, the transport device 321 is divided into blocks by one-dotted lines.
601 is a modem. 602 is an arithmetic unit,
A personal computer having a built-in memory capable of storing transmission / reception data may be used. A device 603 displays and stores the calculation result.

In the arithmetic unit 602, the master station 31 shown in FIG.
Collects the results calculated in the above as data, edits the data so that the accident situation can be easily understood from the outside, displays it on the screen, records it on a line printer, records the data on a floppy disk, etc. I do. The display / storage device 603 performs display of the screen, recording on a line printer, recording on a floppy disk, and the like.

The contents of the arithmetic processing have been described above. For simplicity, in applying the Kirchhoff's law in the system configuration of FIG. 1, the line constant of the transmission line 20 is treated as a uniform distribution. It corresponds to the reciprocating impedance at the time of wire ground fault, and when Z (Ω / km),
The voltage equations for the fault point F from the terminal and the R terminal are given by Equations 4 and 5. In this equation, L is the entire length of the transmission line 20 and is known, so the distance M to the unknown accident point is known.
Then, the accident point resistance RF can be calculated.

[0027]

(Equation 4)

[0028]

(Equation 5)

Here, it is clear from equations (4) and (5) that the accuracy of the line constant Z can be a factor directly affecting the calculation characteristics of the accident situation identification device 50.

In the present invention, the influence of the presence or absence of an overhead ground wire is considered in order to set the line constant Z to a value that matches the actual one as much as possible. FIG. 7 shows a transmission line tower model, in which a tower 28 is shown.
The transmission line 20 is insulated and supported. The overhead ground wire 29 is grounded through a steel tower. In such a state, for example, if all the currents at the time of one line ground fault pass through the ground return path, the inductance Le among the line constants Z at that time is considered as shown in FIG. Desired. In Expression 6, (h + H) corresponds to twice the depth He of the equivalent large ground in FIG.

[0031]

(Equation 6)

However, if an overhead ground wire is installed in the transmission line 20, and if all of the ground fault currents return to the overhead ground wire, as shown in FIG. The distance is shorter than that, and the inductance shown in Equation 6 is correspondingly smaller. For example, it is not uncommon for a ground fault wire to be several tens of meters from the ground surface and several meters from an overhead ground wire.

In this case, a comparison is made between the case where the ground fault current is the return to the overhead ground line and the case where the ground return current is the return to the ground.
It is also conceivable that the latter has an inductance Le that is about 1.5 times larger than the former. Therefore, the value of the line constant Z used in Equations 4 and 5 is determined based on whether the ground fault current is the return path to the overhead ground wire or the return path to the ground, and the value corrected by the ratio is used. This has the effect of increasing the accuracy of the 50 calculation results.

For example, when the line constant when returning to the ground is ZE and the line constant when returning to the overhead ground line is ZW, the line constant Z used in the calculation of Equations 4 and 5 is as shown in Equation 7. And a value proportional to the ratio of the return current. However, in Equation 7, the total return path of the ground fault current is set to 1, of which the ground return path is N, and the remaining overhead ground wire is 1-N.

[0035]

(Equation 7)

If the current returning from the overhead ground wire is smaller than the ground return current by about 10% or less, the line constant ZE under the ground return condition is used for the calculation.
Is an economical advantage that the burden of calculating the line constant Z required as a settling value in advance can be reduced.

The line constant Z indicates Z11 to Z16, Z21 to Z26, and Z61 to Z66 of Equation 1 in the case of a two-line transmission line. In the arithmetic unit, the impedance matrix of the line shown in FIG. input. The input is performed by the accident situation identification device 511 in FIG.
If the system conditions change, the setting can be changed successively.

[0038]

As described above, according to the present invention, it is possible to improve the performance of the accident mode identification device for locating the fault point of the transmission line and calculating the fault point resistance, and the settling value of the line constant can be easily settled by the maintenance staff. This has the effect of increasing the reliability of system operation and reducing the economic burden on settling calculations.

[Brief description of the drawings]

FIG. 1 is an overall explanatory view of the present invention.

FIG. 2 is an explanatory diagram of a calculation method using a two-terminal parallel two-circuit transmission line.

FIG. 3 is an impedance matrix of a line.

FIG. 4 is an operation flowchart.

FIG. 5 is a system configuration diagram of a master station device including data collection and a central device.

FIG. 6 is a configuration diagram of a terminal at a partner terminal.

FIG. 7 is a tower model of a transmission line.

FIG. 8 is an explanatory diagram of calculating a line constant.

[Explanation of symbols]

11, 12 ... three-phase AC power supply, 13, 14 ... power supply neutral point impedance, 20 ... transmission line, 50 ... accident state identification device 21, 22, ... current transformer, 23, 24 ...
... voltage transformers, 31, 32 ... data collection devices.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sonsho Yanagita 15-1, Ushijima-cho, Toyama City, Toyama Prefecture Hokuriku Electric Power Co., Inc. (56) References JP-A-2-74877 (JP, A) JP-A-3 -259755 (JP, A) JP-A-62-98273 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/08 H02H 3/38 H02H 7/26 H02J 13/00

Claims (1)

(57) [Claims] As means for inputting a voltage and current signal of a transmission line and locating a fault point, a line constant corrected by a ratio of a fault current of a transmission line to be measured to an overhead ground line and a ground is used. Characteristic accident condition identification device.