JP2012198134A - Fault point locating device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fault point locating device capable of accurately locating a fault point even when both of a zero-phase current flowing in a sound line and a zero-phase current flowing in a fault line cannot be measured in a parallel two-line power transmission line.SOLUTION: An electric power system provided with first and second bus lines, a parallel two-line transmission line including first and second transmission lines and disposed between the first and second bus lines, and a neutral point ground resistor disposed on the second bus line comprises: a current measuring part for measuring a first zero-phase current flowing from the first bus line to the first transmission line; a voltage measuring part for measuring a zero-phase voltage of the first bus line or the first transmission line; a calculation part for calculating a second zero-phase current flowing from the second bus line to the transmission line where a fault occurs among the first and second transmission lines, based on a first current and the first zero-phase current flowing through the neutral point ground resistor according to the zero-phase voltage, when a ground fault accident occurs in the first or second transmission line; and a locating part for locating a fault point where the ground fault accident occurs based on the first zero-phase current and the second zero-phase current.

Description

  The present invention relates to an accident point location device and a program.

As a method for locating an accident point of a ground fault occurring in a transmission line, for example, a diversion ratio calculation method (I ₀ method) and a reactance calculation method (R method) are known (for example, see Patent Document 1). .

Japanese Patent Laid-Open No. 2003-14810

  In general, when a fault point (failure point) in a parallel two-line transmission line provided with a neutral point grounding resistance is determined, the shunt ratio calculation method can more accurately determine the fault point than the reactance calculation method. However, when the shunt ratio calculation method is used, it is necessary to measure both the zero-phase current flowing in the fault line in which the fault of the parallel two-line transmission line has occurred and the zero-phase current flowing in the healthy line. For this reason, when the zero phase current of both the fault line and the healthy line cannot be measured, there is a problem that the fault point cannot be accurately determined.

  The present invention has been made in view of the above problems, and even when both the zero-phase current flowing in the healthy line and the zero-phase current flowing in the accident line in the parallel two-line transmission line cannot be measured, the accident point can be accurately obtained. An accident point locating device capable of locating

  In order to achieve the above object, according to one aspect of the present invention, a parallel two-line transmission provided between the first and second buses including the first and second buses and the first and second transmission lines. An accident point locating device in an electric power system comprising an electric wire and a neutral point grounding resistance provided on the second bus, and measuring a first zero-phase current flowing from the first bus to the first transmission line A current measurement unit that performs measurement, a voltage measurement unit that measures a zero-phase voltage of the first bus or the first power transmission line, and the voltage measurement when a first ground fault occurs in the first or second power transmission line. A first current flowing through the neutral grounding resistance according to the zero-phase voltage measured at the first section, and the first zero-phase current measured at the current measuring section when the first ground fault occurs. Based on the above, out of the first or second transmission line, the first ground fault from the second bus A calculation unit that calculates a second zero-phase current flowing through the generated transmission line, the first zero-phase current measured by the current measurement unit when the first ground fault occurs, and the second And an orientation part that locates the fault point where the first ground fault has occurred based on the zero-phase current.

  Provided is an accident point locating apparatus capable of accurately locating an accident point even when both a zero phase current flowing in a healthy line and a zero phase current flowing in an accident line in a parallel two-line transmission line cannot be measured. be able to.

It is the figure which showed the electric power grid | system 10 provided with the accident point location apparatus 45 which is one Embodiment of this invention. It is a figure which shows the functional block implement | achieved by the accident point location apparatus 45. FIG. It is a flowchart which shows an example of the process which the accident point location apparatus 45 performs. It is a figure for demonstrating the zero phase electric current at the time of a ground fault occurring in the power transmission line 31. FIG.

At least the following matters will become apparent from the description of this specification and the accompanying drawings.
FIG. 1 is a diagram illustrating a configuration example of an electric power system 10 provided with an accident point locating device 45 according to an embodiment of the present invention.

  The power system 10 is a so-called parallel two-line power transmission system, and the power system 10 is provided with electric stations A and B and power transmission lines 30 and 31.

  The bus 20 (first bus) at the electric station A and the bus 21 (second bus) at the electric station B are connected by power transmission lines 30 and 31, and the bus 21 has a neutral point ground resistance. 35 is connected. Note that each of the buses 20 and 21 and the power transmission lines 30 and 31 includes, for example, three electric wires, but for the sake of convenience, they are illustrated as one line in FIG.

  In the electric station A, a current transformer 40, a zero-phase voltage detection device 41, and an accident point locating device 45 are provided.

  The current transformer 40 is a so-called zero-phase current transformer, and detects a zero-phase current Iox flowing from the bus 20 to the transmission line 31 (first transmission line) when a ground fault occurs in the transmission lines 30 and 31. To do. Zero phase voltage detection device 41 detects zero phase voltage Vo of bus 20.

  The accident point locating device 45 is, for example, a fault locator or an oscilloscope system, and locates an accident point of a ground fault occurring in the transmission lines 30 and 31 based on the zero phase current Iox and the zero phase voltage Vo. The accident point locating device 45 includes a ground fault overvoltage relay 50, a ground fault direction relay 51, a storage device 52, a microcomputer 53, and a display unit 54. Each of the storage device 52, the microcomputer 53, and the display unit 54 is communicably connected via a bus.

  The ground fault overvoltage relay 50 detects whether or not a ground fault has occurred in the transmission lines 30 and 31 based on the zero-phase voltage Vo.

  The ground fault direction relay 51 determines a power transmission line in which a ground fault has occurred among the power transmission lines 30 and 31 based on the zero phase current Iox and the zero phase voltage Vo. The detection result of the ground fault overvoltage relay 50 and the determination result of the ground fault direction relay 51 are input to the microcomputer 53.

  The storage device 52 is, for example, a hard disk device, and the voltage value of the zero-phase voltage Vo when a complete ground fault (predetermined second ground fault) occurs in the program executed by the microcomputer 53 or in the transmission lines 30 and 31. Vm and the current value Im (second current) of the neutral point grounding resistor 35 are stored.

  The microcomputer 53 determines the accident point that has occurred in the power transmission lines 30 and 31 by executing the program stored in the storage device 52.

  The display device 54 is a liquid crystal display or the like, and displays, for example, a calculated accident point.

== Function Blocks Realized in the Accident Pointing Device 45 ==
FIG. 2 is a diagram showing functional blocks implemented in the accident point locating device 45 when the microcomputer 53 executes the program. In the accident point locating device 45, a ground fault detecting unit 80, a current measuring unit 81, a voltage measuring unit 82, a calculating unit 83, and a locating unit 84 are realized.

  The ground fault detection unit 80 detects whether or not a ground fault has occurred in the transmission lines 30 and 31 based on the output of the ground fault overvoltage relay 50.

  When the occurrence of a ground fault is detected by the ground fault detection unit 80, the current measurement unit 81 measures the zero phase current Iox (first zero phase current) detected by the current transformer 40 and stores it in the storage device 52. Store. In addition, the ground fault accident detected by the ground fault detection unit 80 is a ground fault accident that actually occurs in the transmission lines 30 and 31, and corresponds to the first ground fault.

  When the ground fault detection unit 80 detects the occurrence of a ground fault, the voltage measurement unit 82 measures the zero phase voltage Vo detected by the zero phase voltage detection device 41 and stores the measurement result in the storage device 52. .

  After the ground fault is detected, the calculation unit 83 sets the neutral point grounding resistor 35 based on the zero-phase voltage Vo and zero-phase current Iox, the voltage value Vm, and the current value Im stored in the storage device 52. A flowing current Io (first current) and a zero-phase current Ioy (second zero-phase current) flowing from the bus 21 to the power transmission line where the accident has occurred are calculated.

  The orientation unit 84 locates the fault point based on the zero-phase current Iox measured by the current transformer 40 and the zero-phase current Ioy calculated by the calculation unit 83. Specifically, the orientation unit 84 performs an accident point location by executing a shunt ratio calculation method using the zero-phase currents Iox and Ioy.

== An example of processing executed by the accident point locator 45 ==
FIG. 3 is an example of a process executed by the accident point locating device 45 when a ground fault occurs on the transmission lines 30 and 31. The main body of the flowchart of FIG. 3 is each functional block shown in FIG. FIG. 4 is a diagram schematically showing a zero-phase current generated when a ground fault occurs in the power transmission line 31, and is referred to as appropriate.

  First, the ground fault detection unit 80 detects whether or not a ground fault has occurred in the power transmission lines 30 and 31 (S100). When the occurrence of the ground fault is detected (S100: YES), the current measuring unit 81 measures the zero phase current Iox and stores it in the storage device 52, and the voltage measuring unit 82 measures the zero phase voltage Vo. And stored in the storage device 52 (S101).

The calculation unit 83 calculates a ratio α between the value of the zero-phase voltage Vo stored in the storage device 52 and the voltage value Vm when a ground fault occurs (S102). Specifically, the calculation shown in Expression (1) is executed.
α = Vo / Vm (1)
In addition, when the ground fault has not occurred in the transmission lines 30 and 31, the value of the zero phase voltage Vo becomes zero, and when the complete ground fault has occurred in the transmission lines 30 and 31, it is zero. The value of the phase voltage Vo is the voltage value Vm. Therefore, the ratio α is a value indicating the so-called ground fault level and changes in the range of 0-1. Further, the larger the value of the ratio α, the closer the ground fault accident becomes to the complete ground fault accident.

Then, the calculation unit 83 calculates the product of the ratio α indicating the calculated degree of ground fault and the current Im flowing through the neutral point grounding resistor 35 at the time of complete ground fault, so that when a ground fault occurs. A current Io flowing through the neutral point grounding resistor 35 is calculated (S103). Specifically, the calculation shown in Expression (2) is executed.
Io = α × Im (2)
The current Io flowing through the neutral point grounding resistor 35 increases in proportion to the degree of ground fault (that is, the zero-phase voltage Vo). Therefore, in this embodiment, the current Io can be calculated without actually measuring the current Io by executing the calculation of the equation (2).

Further, as illustrated in FIG. 4, the current Io flowing through the neutral point grounding resistor 35 when the ground fault occurs occurs, and the zero-phase current Iox flowing from the bus 20 to the power transmission line 31 and the power transmission line 31 from the bus 21. And the zero-phase current Ioy flowing through Therefore, the calculation unit 83 calculates the zero phase current Ioy by subtracting the zero phase current Iox at the time of occurrence of the ground fault from the calculated current Io (S104). Specifically, the calculation shown in Expression (3) is executed.
Ioy = Io−Iox (3)
Thus, in this embodiment, the value of the zero phase current Ioy can be calculated. Then, the orientation unit 84 identifies the fault line from the determination result of the ground fault direction relay 51, and based on the zero phase current Iox stored in the storage device 52 and the calculated zero phase current Ioy, Accident points are located (S105).

Specifically, for example, in FIG. 4, when the length of the transmission lines 30 and 31 is “1” for convenience and the distance from the bus 20 to the accident point A is “X”, between the zero-phase currents Iox and Ioy Is a relational expression as shown in Expression (4).
Ioy: Iox = 1 / (1-X): 1 / (1 + X) (4)
In addition, the relationship of said Formula (4) is a relationship obtained based on a general diversion ratio calculation system. Further, the distance “X” from the bus 20 to the accident point A is expressed by the equation (5).
X = (Ioy−Iox) / (Iox + Ioy) (5)
For this reason, the orientation unit 84 can determine the accident point A by executing the calculation of Expression (5) in the process S105.
When the accident point A is located, the orientation unit 84 displays the position of the accident point A on the display unit 54 (S106).

  In the above, the accident point location apparatus 45 which is one embodiment of this invention was demonstrated. The accident point locating device 45 includes a zero-phase current (zero-phase current Iox in the example of FIG. 4) flowing through a healthy line in a parallel two-line transmission line, and a zero-phase current (zero-phase current in the example of FIG. 4). Ioy), the zero-phase current Ioy is calculated. Therefore, even if the accident point locating device 45 cannot measure both of the zero-phase currents Iox and Ioy, the accident point can be determined based on an accurate diversion ratio calculation method. As a result, for example, the user can install the accident point locating device 45 even in the electric station A where the neutral point grounding resistor 35 is not provided and both the zero-phase currents Iox and Ioy cannot be measured. it can.

  In addition, the accident point locating device 45 obtains the degree of ground fault (ratio α) from the zero-phase voltage Vo when the ground fault occurs and the voltage value Vm, and then neutralizes when the ground fault occurs. The current Io flowing through the point grounding resistor 35 is obtained. The current Io flowing through the neutral point grounding resistor 35 increases in proportion to the ground fault degree. For this reason, in the present embodiment, the current Io can be accurately calculated without measuring the current Io.

  In general, the voltage value Vm when a complete ground fault occurs is a standard in the electrical standards study group of the Institute of Electrical Engineers, and is determined to be 110 V, for example. In addition, the current Im when a complete ground fault occurs is determined by the resistance value of the neutral point grounding resistor 35. For this reason, the user can determine the voltage values Vm and Im to be stored in the storage device 52 without performing special calculations or the like in advance.

  In addition, the said Example is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  In this embodiment, when a complete ground fault (so-called 100% ground fault) occurs, the values of the zero-phase voltage Vo and the current Io are the voltage value Vm and the current value Im, respectively. Not limited. As described above, the current Io flowing through the neutral point grounding resistor 35 increases in proportion to the degree of ground fault. For this reason, for example, the values of the zero-phase voltage Vo and the current Io when a 50% ground fault occurs may be set as the voltage value Vm and the current value Im, respectively. In this case, the ratio α changes from 0 to 2, but the accident point can be accurately determined as in the present embodiment.

  Moreover, although the accident point locating apparatus 45 calculated by calculating the electric current Io by process S102, S103, it is not restricted to this. For example, there is a relationship of Io = α × Im = (Vo / Vm) × Im between the current Io and the zero-phase voltage Vo. In other words, the current Io when an actual ground fault has occurred changes according to the zero-phase voltage Vo. For this reason, data indicating the correlation between the current Io and the zero-phase voltage Vo is stored in the storage device 52 in advance, and the microcomputer 53 uses the above-described data and the measured zero-phase voltage Vo to obtain the zero-phase voltage Vo. The corresponding current Io may be appropriately selected.

  Further, the zero-phase voltage detection device 41 detects the zero-phase voltage Vo of the bus 20, but may be, for example, the zero-phase voltage of the power transmission line 31 on the bus 20 side (the power transmission line 31 near the bus 20). . Even in this case, the accident point locating device 45 can determine the accident point as in the present embodiment.

DESCRIPTION OF SYMBOLS 10 Electric power system 20,21 Bus line 30,31 Transmission line 40 Current transformer 41 Zero phase voltage detection apparatus 45 Fault location device 50 Ground fault overvoltage relay 51 Ground fault direction relay 52 Memory | storage device 53 Microcomputer 54 Display part 80 Ground fault detection part 81 Current Measurement Unit 82 Voltage Measurement Unit 83 Calculation Unit 84 Orientation Unit

Claims (4)

A parallel two-line power transmission line including the first and second bus lines, including the first and second power transmission lines and provided between the first and second bus lines, and a neutral grounding resistance provided on the second bus line An accident point locating device in a power system comprising:
A current measuring unit for measuring a first zero-phase current flowing from the first bus to the first power transmission line;
A voltage measuring unit for measuring a zero-phase voltage of the first bus or the first power transmission line;
A first current flowing through the neutral grounding resistance according to the zero-phase voltage measured by the voltage measuring unit when a first ground fault occurs in the first or second transmission line; Based on the first zero-phase current measured by the current measuring unit when a ground fault occurs, the first ground fault from the second bus of the first or second power transmission line A calculation unit that calculates a second zero-phase current flowing in the generated transmission line;
Based on the first zero-phase current and the second zero-phase current measured by the current measuring unit when the first ground fault occurred, the fault point where the first ground fault occurred was determined. An orientation part for orientation;
An accident location system characterized by comprising: The accident point locating device according to claim 1,
The calculation unit includes:
The zero-phase voltage when a predetermined second ground fault occurs, the second current flowing through the neutral point ground resistance when the second ground fault occurs, and the first ground fault occur And calculating the first current based on the zero-phase voltage measured by the voltage measuring unit, and then measuring the current when the first ground fault occurs from the calculated first current. Subtracting the first zero-phase current measured in the unit to calculate the second zero-phase current;
Accident point locator characterized by The accident point locating device according to claim 2,
The second ground fault is a complete ground fault;
Accident point locator characterized by A parallel two-line power transmission line including the first and second bus lines, including the first and second power transmission lines and provided between the first and second bus lines, and a neutral grounding resistance provided on the second bus line In a power system comprising:
On the computer,
A function of measuring a first zero-phase current flowing from the first bus to the first power transmission line;
A function of measuring a zero-phase voltage of the first bus or the first power transmission line;
When a ground fault occurs in the first or second power transmission line, a current that flows through the neutral point ground resistance according to the zero-phase voltage measured by the voltage measuring unit, and the ground fault occurs. On the basis of the first zero-phase current measured by the current measuring unit, the first or second power transmission line flows from the second bus to the power transmission line in which the ground fault occurred. A function of calculating a second zero-phase current;
A function of locating the fault point where the ground fault occurred, based on the first zero phase current and the second zero phase current measured when the ground fault occurred;
A program to realize

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