JP2010127913A - Transmission line fault point locator, and method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply a transmission line fault point locator also to a transmission line having a branch line and to allow high fault point locating accuracy. <P>SOLUTION: A fault point is located based on an amplitude value of an own-end assumed fault point rotation vector variation voltage and an amplitude value of a counter-end assumed fault point rotation vector variation voltage. The own-end assumed fault point rotation vector variation voltage is calculated as a rotation vector variation voltage when a fault is assumed to occur at an assumption point, using an own-end voltage rotation vector variation, an own-end current rotation vector variation, and a second impedance to the assumption point as a virtual point on a transmission line separated from the measuring point on the own-end side by a predetermined distance. The counter-end assumed fault point rotation vector variation voltage is calculated as a rotation vector variation voltage when a fault is assumed to occur at the assumption point, using a counter-end voltage rotation vector variation, a counter-end current rotation vector variation, and a third impedance from the measuring point on the counter-end side to the assumption point. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power transmission line accident point locating apparatus and a power transmission line accident point locating method that can determine a fault point due to an accident (for example, ground fault, short circuit accident, etc.) that has occurred in a transmission line.

  As a power transmission line accident point location device, for example, there is one shown in Patent Document 1 below. In the transmission line accident point locating device disclosed in Patent Document 1, the current shunt ratio or impedance is obtained for each instantaneous value based on the actually measured data of the transmission line, and the current shunt ratio for a predetermined period after the occurrence of the accident is averaged. A configuration is provided that includes a current shunt ratio / impedance calculation unit that performs an accident and a fault location unit that locates an accident point of a ground fault / short circuit accident based on the obtained average current shunt ratio and the like.

JP 2004-215478 A

  If there is an accident on the transmission line, the transmission line accident point location device is used to locate the accident point of the transmission line, and the maintenance staff will rush to the site immediately after the accident occurs to identify the final accident point. There is a need. For this reason, in order for maintenance personnel to work efficiently, the power line accident point locating apparatus is required to have higher locating accuracy.

  On the other hand, the transmission line accident point locating apparatus disclosed in Patent Document 1 describes that the fault point of a ground fault can be determined with high accuracy while using the current shunt ratio method or the impedance method.

  However, since the transmission line accident point locating device of Patent Document 1 is a method of calculation using the accident voltage / accident current itself, it is easily affected by the accident point resistance and the accuracy of the orientation calculation result is not improved. There was a problem.

  Moreover, in the conventional transmission line accident point location devices including the above-mentioned Patent Document 1, when the transmission line has a branch line, it is affected by the current flowing in and out of the branch line, and the accuracy of the accident point location calculation deteriorates. There was a problem.

  The present invention has been made in view of the above, and can be applied to a transmission line having a branch line, and a transmission line accident point location device and a transmission line accident that enable highly accurate accident point location accuracy. The purpose is to provide a point location method.

  In order to solve the above-described problems and achieve the object, a power transmission line accident point locating device according to the present invention includes a rotation vector including a change in voltage rotation vector, a change in current rotation vector, and a rotation vector starting voltage as elements. In the transmission line accident point locating device for locating the accident point in the power transmission line to be standardized using the variation equivalent circuit, the rotation based on the self-end voltage instantaneous value data measured on the self-end side of the transmission line A first calculation unit that calculates a change in the voltage rotation vector that is a change in the voltage rotation vector on the own end side of the vector change equivalent circuit; and an own end measured on the own end side of the transmission line A second calculation unit that calculates a change amount of the current rotation vector that is a change amount of the current rotation vector on the own end side of the rotation vector change equivalent circuit based on the instantaneous current value data; Using the first-end voltage rotation vector change, the own-end current rotation vector change, and the first impedance from the own end to the other end of the transmission line, the rotation vector change equivalent circuit on the own end side A third calculation unit that calculates a self-end rotation vector start-up voltage that is a rotation vector start-up voltage, and a fourth calculation unit that calculates a self-end rotation vector start-up voltage change that is a change in the self-end rotation vector start-up voltage; The other end voltage rotation that is a change in the voltage rotation vector on the other end side of the rotation vector variation equivalent circuit based on the other end voltage instantaneous value data measured at the other end and transmitted to the other end. Based on the other end current instantaneous value data measured at the other end and transmitted to the own end, the fifth calculation unit for calculating the vector change, the rotation vector change, etc. A sixth calculation unit for calculating a change amount of the other end current rotation vector that is a change amount of the current rotation vector on the opposite end side of the circuit; a change amount of the own end voltage rotation vector; a change amount of the own end current rotation vector; And a rotation vector change voltage when it is assumed that an accident has occurred at the assumed point using the second impedance to the assumed point which is a virtual point on the transmission line that is a predetermined distance away from the measurement point on the own end side. Assumed from the measured value on the other end side, the amplitude value of the own end assumed accident point rotation vector change voltage calculated as, the other end voltage rotation vector change amount, the other end current rotation vector change amount, and The other end assumed accident point rotation vector calculated as a rotation vector change voltage when it is assumed that an accident has occurred at the assumed point using the third impedance up to And an accident point calculation unit for locating the accident point based on the amplitude value of the change voltage.

  According to the power transmission line accident point locating device according to the present invention, the self-end voltage rotation vector change amount, the self-end current rotation vector change amount, and the virtual point on the transmission line that is a predetermined distance away from the self-end measurement point. Using the second impedance up to the assumed point, the amplitude value of the assumed accident point rotation vector change voltage calculated as the rotation vector change voltage when it is assumed that an accident has occurred at the assumed point, and the counterpart voltage Rotation vector change voltage when assuming that an accident has occurred at the assumed point using the rotation vector change, the counterpart current rotation vector change, and the third impedance from the measurement point on the counterpart side to the assumed point Since the accident point is determined based on the amplitude value of the voltage at the other end of the assumed accident point rotation vector calculated as follows, it is possible to obtain highly accurate accident point localization accuracy. The effect of wear can be obtained.

  Moreover, according to the transmission line accident point locating device according to the present invention, when there are one or more branch lines on the transmission line, the rotation vector variation voltage at the first branch point from the transmission line of the branch line is self-terminal. Applied as the voltage rotation vector change or the other end voltage rotation vector change, and the rotation vector change current at the second branch point adjacent to the first branch point is used as the current end current rotation vector change amount or the other end current. By applying it as a rotation vector change, an effect that an accident point between adjacent branch points can be determined is obtained.

(Introduction)
The inventor of the present application has derived a power transmission line fault location device and a power transmission line fault location method that can be applied to a transmission line having a branch line based on the knowledge about the equivalent circuit for the rotation vector change in the spiral vector theory. It was. DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a power transmission line accident location device and a power transmission line accident location method according to the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

(Definition of terms)
The spiral vector theory that is the basis of the transmission line accident point location apparatus and the transmission line accident point location method according to the present invention is not fully in the world. First, terms used in this specification are defined.

-Transmission line accident point locating device: A device for locating an accident point in a transmission line (overhead transmission line, cable, etc.).
Rotation vector: A rotation vector is a dynamic phasor that rotates counterclockwise on a complex plane, and an actual measurement value is a real part of the rotation vector. In recent AC theory, it is common practice to simulate an AC wave with a cosine function (in the conventional AC theory, an AC wave is simulated with a sine function).
Voltage rotation vector: a voltage state variable, whose real part is an actually measured voltage instantaneous value.
Current rotation vector: A current state variable whose real part is an instantaneous measured current value.
Rotational vector change: A difference component between two rotational vectors before or after one or several cycle times. Like the rotation vector, the rotation vector change has a real part and an imaginary part, and is a complex state variable.
Voltage rotation vector change: A voltage state variable, which is a difference component between the voltage rotation vector at the reference time point and the voltage rotation vector at the time point one or several cycles before the reference time point.
Current rotation vector change: A current state variable, which is a difference component between a current rotation vector at a reference time point and a current rotation vector at a time point one or several cycles before.
・ Assumed accident point: Virtual point on the transmission line assuming the occurrence of the accident ・ Virtual power source: Virtual power source with voltage amplitude before accident and inserted at the assumed accident point ・ Rotation vector change equivalent circuit: Voltage rotation It is a circuit configured by a vector change, a current rotation vector change, and a virtual power supply. In the steady state, there is no rotation vector equivalent circuit, and it appears when the state of the system changes due to an accident or the like.
Self-rotation vector starting voltage: a starting voltage calculated using the self-rotating vector voltage, the self-rotating vector current, and the impedance from the self-terminal to the counterpart. This starting voltage is the virtual power supply voltage value (virtual power supply voltage) in the rotation vector variation equivalent circuit.
Self-end rotation vector starting voltage amplitude: Absolute value of the self-end rotation vector starting voltage.
-Own-end rotation vector change start voltage: This is the change start voltage calculated using the impedance from the own end to the other end, the measured rotation vector change, and the rotation vector change equivalent circuit.
-Self-rotation vector change start voltage amplitude: Absolute value of the self-end rotation vector change start voltage.
Self-contained accident point rotation vector change voltage: This is a rotation vector change voltage calculated using the voltage rotation vector change and current rotation vector change at the self-end, and the impedance from the self-end to the assumed accident point.
-Own end assumed accident point rotation vector change voltage amplitude: The absolute value of the own end assumed accident point rotation vector change voltage.
-Counterpart assumed accident point rotation vector change voltage: This is a rotation vector change voltage calculated using the voltage rotation vector change and current rotation vector change in the other party alone, and the impedance from the other end to the assumed accident point.
-Counterparty assumed accident point rotation vector change voltage amplitude: Absolute value of the counterpart end assumed accident point rotation vector change voltage.
-Distance coefficient k: 0-100% coefficient. k = 0% is the own end, and k = 100% is the other end.
・ Estimated accident point calculation processing at both ends: The distance coefficient k is changed, various impedances are assumed, and the own end assumed accident point rotation vector voltage amplitude and the other end assumed accident point rotation vector voltage amplitude are calculated. This is a calculation process in which the distance coefficient k corresponding to the intersection of the curves is the distance coefficient to the accident point.
-Both-end assumed accident point convergence calculation processing: In the both-end assumed accident point calculation processing, the distance coefficient before and after the intersection of both curves is set to a new variable range, and the increment width of the distance coefficient is reduced to determine the intersection of both curves. This is a process for increasing the accuracy of locating the distance coefficient k corresponding to the accident point by repeatedly performing the required process.
The Institute of Electrical Engineers of Japan EAST10 model system: A model system established in Japan, and a typical model system for simulating an electric power system.
・ Short-circuit accident: Inter-phase accident such as AB phase accident, BC phase accident, AC phase accident, ABC phase accident, etc. There is no zero phase component in the circuit.
・ Ground fault: Grounding accident due to A phase grounding, B phase grounding, C phase grounding, AB phase grounding, BC phase grounding, AC phase grounding, ABC phase grounding, etc. Unlike a short circuit accident, there is a zero phase component in the circuit.

(Device configuration)
FIG. 1 is a diagram showing a configuration of a power transmission line accident point location apparatus according to an embodiment of the present invention. In FIG. 1, a transmission line accident point locating device 1 according to the present embodiment includes a self-end voltage / current measurement / A / D conversion unit 2 and a self-end voltage rotation vector change calculation unit 3 as a first calculation unit. , Self-end current rotation vector change calculation section 4 as the second calculation section, self-end rotation vector start-up voltage calculation section 5 as the third calculation section, self-end rotation vector change start as the fourth calculation section As a voltage calculation unit 6, a local terminal accident determination unit 7, a counterpart voltage / current time series data reception unit 8, a counterpart voltage rotation vector change calculation unit 9 as a fifth calculation unit, and a sixth calculation unit The other end current rotation vector change calculation unit 10, the accident point calculation unit 11, the interface 12, the storage unit 13, and the remote transmission unit 14 are provided. Here, the transmission line accident point locating device 1 is a device installed at one end (own end) of a protection section of the transmission line, and is equivalent to the other end (partner end) of the protection section of the transmission line. A transmission line accident point locating device (illustrated as the counterpart device 15) is arranged.

(Function of each component)
Next, functions of the components shown in FIG. 1 will be described. Here, only the description of the schematic function will be given here, and the detailed function of each part will be described in the flowchart described later.

  The own-end voltage / current measurement / A / D converter 2 uses PT16, which is an instrument transformer installed at the device arrangement end, and CT13, which is a current transformer installed on a transmission line near the device arrangement end. In addition to measuring the system voltage at the device placement end and the current flowing in the transmission line, the reference wave 1 period is equally divided into 4N (N is a positive integer) with respect to the measured voltage (measurement voltage) and current (measurement current). Time-series digital data (self-end voltage instantaneous value data and self-end current instantaneous value data) obtained by sampling at each sample timing is generated.

  The self-end voltage rotation vector change calculation unit 3 uses the instantaneous voltage value data generated by the self-end voltage / current measurement / A / D conversion unit 2 to calculate the change of the voltage rotation vector in each phase of the self-end. The self-end current rotation vector change calculation unit 4 uses the current instantaneous value data generated by the self-end voltage / current measurement / A / D conversion unit 2 to change the current rotation vector in each phase of the self-end. Is calculated.

  The self-rotation vector starting voltage calculation unit 5 uses the voltage instantaneous value data and the current instantaneous value data to calculate the voltage rotation vector, the current rotation vector, and the impedance (first first) Impedance) is used to calculate the own-end rotation vector starting voltage that is the rotation vector starting voltage when the other end is viewed from the own end.

  The self-end rotation vector change amount startup voltage calculation unit 6 includes the self-end voltage rotation vector change amount calculation unit 3 and the self-end current rotation vector change amount calculation unit 4 generated by the self-end voltage rotation vector change amount and the self-end current rotation vector. Using the change amount and the first impedance, the own-end rotation vector change amount start voltage that is the change amount of the rotation vector start voltage when the other end is viewed from the own end is calculated.

  The self-end area accident discriminating unit 7 determines that an accident that has occurred in the power system is based on the amplitude value of the start-end rotation vector change starting voltage and the amplitude value of the end-end rotation vector start voltage. Accidents) or out-of-city accidents (protection-related accidents).

  The other end voltage / current time series data receiving unit 8 receives the voltage / current time series data (the other end voltage instantaneous value data and the other end current instantaneous value data) measured and generated by the other end device 15 via the communication line. Receive.

  The counterpart voltage rotation vector change calculation unit 9 uses the received counterpart voltage instantaneous value data to calculate a voltage rotation vector change (counter end voltage rotation vector change) in each phase of the counterpart, The other end current rotation vector change calculation unit 10 calculates the amount of change in the current rotation vector (the other end current rotation vector change) in each phase of the other end using the received current instantaneous value data of the other end.

  The accident point calculation unit 11 relates to an assumed accident point (assumed accident point), and an amplitude curve (rotation vector voltage amplitude curve: first end assumed accident point rotation vector voltage amplitude curve) representing the rotation vector change voltage calculated based on the own end data. Curve) and the distance coefficient k corresponding to the intersection of the two curves of the amplitude curve representing the rotation vector change voltage calculated based on the other end data (partner end assumed accident point rotation vector voltage amplitude curve: second curve). Is used as a distance coefficient to the accident point, and at the same time, calculation is performed to increase the location accuracy of the accident point.

  The interface 12 provides an output function for outputting the above calculation result to an external device or the like. The storage unit 13 provides a storage function for holding the above-described various calculation results. The remote transmission unit 14 has a function for transmitting voltage / current time-series data (self-end voltage / current time-series data) measured and generated at its own end to the other-end device 15 or a point away from the own-end device. A transmission function is provided to transmit necessary information to monitoring personnel in the station.

  Next, each drawing of FIGS. 1 to 6 necessary for explaining the operation of the power transmission line accident point locating device according to the present embodiment will be described. FIG. 2 is a flowchart showing the operation of the power transmission line accident point location device. Moreover, FIG. 3 is the figure which modeled the electric power system which is the target of the power transmission line accident point location apparatus concerning this Embodiment, More specifically, FIG. 3 (a) is a model system figure of the target of orientation. FIGS. 3B and 3C are diagrams in which FIG. 3A is divided into two equivalent circuits by the superposition theorem of electric circuits, and FIG. 3B is a steady circuit diagram including a power source and a load. , (C) is a rotation vector variation equivalent circuit (also referred to as “failure component circuit”). FIG. 4 is an equivalent circuit diagram in which the circuit of FIG. 3C is more concretely shown, and particularly shows an equivalent circuit in the case of a short circuit accident. FIG. 5 is an equivalent circuit diagram showing the concept of the calculation process of the assumed accident point. FIG. 6 is a diagram showing the concept of the calculation process of the distance coefficient k corresponding to the accident point.

In FIG. 4, the meaning of each symbol is as follows.
M: Own end bus N: Counter end bus Z ₁ : Transmission line impedance Z _M : M bus rear impedance Z _N : N bus rear impedance F: Accident point Δv: Rotation vector change voltage Δi: Rotation vector change current v _F : Rotation vector starting voltage (virtual power supply voltage)

  In the above description, the other end bus N is set at the other end, but a method may be used in which the impedance of the transmission line is set 5% higher for reliable start-up.

  In the steady state, an equivalent circuit for the rotation vector change does not exist, but when the system state changes due to an accident or the like, a virtual power supply voltage is generated and a voltage rotation vector change and a current rotation vector change appear. However, when one or several cycles have passed since the accident occurred, each rotation vector change disappears. The virtual power supply in the rotation vector variation equivalent circuit is set as a virtual power supply that is inserted at the assumed accident point. The amplitude of this virtual power supply is the voltage before the accident at the assumed accident point at which the virtual power supply is inserted. An amplitude value is set.

In FIG. 5, the meaning of each symbol is as follows.
M: Own end bus N: Transmission line end bus V ₁ : Rotation vector voltage measured at own end (own end rotation vector voltage)
Δv ₁ : Rotational vector change component voltage measured at own end (own end rotational vector voltage)
i ₁ : rotation vector current measured at its own end (own end rotation vector voltage)
Δi ₁ : Rotation vector change current measured at its own end (own end rotation vector voltage)
V ₂ : Rotation vector voltage measured at the other end (own end rotation vector voltage)
Δv ₂ : Rotational vector change voltage measured at the other end (own end rotational vector voltage)
i ₂ : Rotation vector current measured at the other end (own end rotation vector voltage)
Δi ₂ : rotation vector change current measured at the other end (own end rotation vector voltage)
F: Accident point v _F : Rotation vector starting voltage calculated at own end (own end rotation vector starting voltage)

  Next, the operation of the power transmission line accident point locating device according to the present embodiment will be described with reference to the drawings of FIGS.

(Steps S101 and S102)
In steps S101 and S102, initial values relating to variables M and P necessary for processing in this flow are set. The meaning of these variables will be described later.

(Step S103)
In step S103, the self-end voltage / current measurement / A / D converter 2 generates time-series digital data (self-end voltage instantaneous value data and self-end current instantaneous value data). Among these instantaneous value data, the self-end voltage instantaneous value data can be expressed as follows using a Fourier transform equation.

That is, the self-end voltage instantaneous value data is composed of a voltage fundamental wave component and a plurality of voltage harmonic components. Here, the meaning of each symbol in the above equation (1) is as follows.
V: fundamental wave voltage amplitude ω: fundamental wave angular velocity θ: fundamental wave voltage initial phase V _k : k-order harmonic voltage amplitude ω _k : k-order harmonic voltage angular velocity φ _k : k-order harmonic voltage initial phase M: positive integer

  In the following description, the voltage harmonic component is omitted for the sake of brevity. At this time, when the voltage instantaneous value is represented by a voltage rotation vector (self-end voltage rotation vector), the following equation is obtained.

  Here, the self-end voltage instantaneous value data generated by the self-end voltage / current measurement / A / D converter 2 is substituted into the real part of the above equation (2). In addition, although an imaginary part is calculated | required by a calculation, this point is mentioned later.

  In addition, the self-current instantaneous value data and the current rotation vector based on the self-current current value data (self-current rotation vector) shall be expressed as follows using the Fourier transform equation as in the case of voltage. Can do.

Here, the meaning of each symbol in the above equation (3) is as follows.
I: fundamental wave current amplitude ω: fundamental wave angular velocity θ: fundamental wave current initial phase V _k : k-order harmonic current amplitude ω _k : k-order harmonic current angular velocity θ _k : k-order harmonic current initial phase M: positive integer

  Further, the self-end current rotation vector shown in the above expression (3) can be expressed separately as a real part and an imaginary part as shown in the following expression.

  Here, the self-end current instantaneous value data generated by the self-end voltage / current measurement / A / D converter 2 is substituted into the real part of the above equation (4). Moreover, although an imaginary part is calculated | required by a calculation, this point is mentioned later.

(Step S104)
In step S104, the self-end rotation vector start-up voltage calculation unit 5 calculates a self-end rotation vector start-up voltage that is a rotation vector start-up voltage when the other end side is viewed from the self-end. This self-rotation vector starting voltage can be expressed by the following equation based on the equivalent circuit of the power system model shown in FIG.

Here, the meanings of the symbols in the above equation (5) are as follows.
v _F : Self-end rotation vector starting voltage v: Self-end voltage rotation vector i: Self-end current rotation vector Z ₁ : Impedance to the other end (positive phase impedance)
The subscripts “re” and “im” represent the real part and the imaginary part.

  Further, when the real part and the imaginary part of the formula (5) are separated from each other, the following formula is obtained.

  Further, the amplitude value of the self-end rotation vector starting voltage (self-end rotation vector starting voltage amplitude) is calculated using the following equation.

  The self-rotation vector starting voltage amplitude can also be calculated by the following equation. The advantage of this equation is that the influence of harmonic components in the circuit can be reduced by integral calculation.

  In the above equation (8), N is N when a sampling method is used in which one period of the reference wave is equally divided by 4N (N is a positive integer). For example, if N = 3, the sampling interval is 360 / (4 × 3) = 30 degrees.

(Step S105)
In step S105, the own-end voltage rotation vector change calculation unit 3 calculates the change in the own-end voltage rotation vector. This self-end voltage rotation vector change is calculated using the following equation as a difference value between the self-end voltage rotation vector at time t and the self-end voltage rotation vector one or several cycles before time t. Incidentally, one cycle time T ₀ of the reference wave, for example, in the system of the reference frequency 60 Hz, a T ₀ = 1/60 = 0.0166667 seconds, the system of the reference frequency 50 Hz, T ₀ = 1/50 = 0.02 seconds.

  In the above equation (9), the measured self-end voltage instantaneous value data is substituted into the real part. On the other hand, for example, a value calculated using the following equation is substituted into the imaginary part.

(Step S106)
In step S106, the own-end current rotation vector change amount calculation unit 4 calculates the change amount of the own-end current rotation vector. This self-end current rotation vector change can be calculated using the following equation, similarly to the self-end voltage rotation vector change shown in equation (9) above.

  In the above equation (11), the measured self-end voltage instantaneous value data is substituted for the real part, and the value calculated using, for example, the following equation is substituted for the imaginary part.

(Step S107)
In step S107, a process for determining whether or not an accident has occurred is performed. This determination process can be performed, for example, by comparing the difference value between the current value and the current value one cycle before with a predetermined settling value. If it is determined that no accident has occurred (No at Step S107), the process returns to Step S103. If it is determined that an accident has occurred (Yes at Step S107), the process proceeds to Step S108.

(Step S108)
In step S108, the self-end rotation vector change start voltage calculation unit 6 uses the self-end voltage rotation vector change calculated in step S105 and the self-end current rotation vector change calculated in step S106. A starting voltage corresponding to a change in the own-end rotation vector starting voltage is calculated. This starting voltage for the rotation vector change is expressed by the following equation.

  Further, when the real part and the imaginary part of the formula (13) are separated, the following formula is obtained.

  Furthermore, the amplitude value (starting voltage amplitude for the self-end rotation vector change) of the self-end rotation vector change is calculated using the following equation.

  The starting voltage amplitude corresponding to the self-rotation vector change can also be calculated by the following equation. The advantage of this equation is that the influence of harmonic components in the circuit can be reduced by integral calculation.

(Step S109)
In step S109, a process for determining whether or not the accident determined in step S107 is a ward accident is performed. This determination process can be determined using the following equation. Here, when it is determined that the accident is not within the city (step S109, No), the process returns to step S103, and when it is determined that the accident is within the city (step S109, Yes), the process proceeds to step S110.

  In the above process, the presence or absence of an accident is determined in step S107, and the presence or absence of a city accident is determined in step S109. However, the process in step S107 is omitted, and only the process in step S109 is performed. The presence or absence of an accident (a ward accident) may be determined. In this case, even if there is no accident, the process of step S108 is executed, but since it is a process of one step, the influence on the calculation time is small.

(Step S110)
In step S110, the counterpart voltage / current time series data receiving unit 8 performs reception processing of the counterpart voltage / current time series data measured and generated by the counterpart device 15.

(Step S111)
In step S111, the counterpart voltage rotation vector change calculation unit 9 calculates the counterpart voltage rotation vector change. The amount of change in the other end voltage rotation vector is the difference value between the other end voltage rotation vector at time t and the other end voltage rotation vector one or several cycles before time t, as in the above equation (9). Calculated using the formula.

  In the above equation (18), the received counterpart terminal voltage instantaneous value data is substituted into the real part. On the other hand, for example, a value calculated using the following equation is substituted into the imaginary part.

(Step S112)
In step S112, the other end current rotation vector change calculation unit 10 calculates a change in the other end current rotation vector. The change in the other end current rotation vector can be calculated using the following equation, similarly to the change in the other end voltage rotation vector shown in the above equation (18).

  In the above equation (20), the received counterpart terminal current instantaneous value data is substituted into the real part. On the other hand, for example, a value calculated using the following equation is substituted into the imaginary part.

(Steps S113 to S117)
In steps S113 to S117, calculation processing for estimating an accident point is performed. Details of each process are as follows.

  First, the distance coefficient k is defined as follows:

For example, if k _max = 100, the resistance component and inductance component of one unit are expressed by the following equations.

  Therefore, the resistance and inductance at the impedance (second impedance) from the own end (measurement point on the own end side) to the assumed point (assumed accident point) that is one point on the transmission line that is a predetermined distance away from the own end are: It is given by

  Similarly, the resistance and inductance at the counterpart end (measurement point on the counterpart end side) and the impedance (third impedance) from the counterpart end to the assumed accident point are given by the following equations.

  Note that the variable process of the distance coefficient k is performed in steps S113, S116, and S117.

  In step S114, a voltage amplitude value corresponding to the change of the own-end assumed accident point rotation vector is calculated.

  The self-contained accident point rotation vector change voltage is expressed by the self-end voltage rotation vector change calculated in step S105, the self-end current rotation vector change calculated in step S106, and the above equation (24). It is expressed by the following equation using the resistance and inductance up to the assumed accident point.

  Therefore, the amplitude value of the own end assumed accident point rotation vector change component voltage (the own end assumed accident point rotation vector change component voltage amplitude) is expressed by the following equation using the values of the real part and the imaginary part of the above equation (26). Can be calculated as follows.

  It should be noted that the voltage amplitude corresponding to the change of the rotation vector change at the assumed accident point can also be calculated by the following equation. The advantage of this equation is that the influence of harmonic components in the circuit can be reduced by integral calculation.

  Similarly, in step S115, a voltage amplitude value corresponding to the change of the opponent end assumed accident point rotation vector is calculated.

  The other end assumed accident point rotation vector change current is expressed by the self-end voltage rotation vector change calculated in step S105, the current rotation vector change calculated in step S106, and the above equation (25). It is expressed by the following equation using the resistance and inductance up to the assumed accident point.

  Therefore, the amplitude value of the other end assumed accident point rotation vector change component voltage (the other end assumed accident point rotation vector change component voltage amplitude) is expressed by the following equation using the values of the real part and imaginary part of the above equation (29). Can be calculated as follows.

  In addition, the other party assumption accident point rotation vector change part voltage amplitude can also be calculated by following Formula. The advantage of this equation is that the influence of harmonic components in the circuit can be reduced by integral calculation.

  Thereafter, in step S116, the end condition is determined, and in step S117, the distance coefficient k is incremented. When the calculation for all the distance coefficients is completed, the process proceeds to step S118.

(Steps S118 to S121)
In steps S118 to S121, an assumed accident point determination process is performed based on the number M of matching times and the sampling point designation variable P. This process is a process for increasing the accuracy of the assumed accident and preventing erroneous start-up. Details of each process are as follows.

  In step S118, the accident point calculation unit 11 determines whether or not there is an intersection point between the curve representing the voltage amplitude corresponding to the assumed end accident point rotation vector change and the curve representing the voltage amplitude corresponding to the other end assumed accident point rotation vector. Judgment processing is executed.

Not Here, local end assumed fault point rotation vector variation voltage amplitude vF ₁ (k), or the rotation vector variation voltage amplitude remote end assumed fault point is represented by vF ₂ (k), there is an intersection in the two curves Such determination processing is executed based on the following two expressions (see FIG. 6).

The meanings of the symbols in the above equations (32) and (33) are as follows.
vF ₁ (k _n): distance factor k local end assumed fault point in _n rotation vector variation voltage amplitude vF ₂ (k _n): distance factor k remote end assumed fault point in _n rotation vector variation voltage amplitude vF ₁ (k _{n + 1} ): Voltage amplitude corresponding to the assumed end-of-life accident point rotation vector at the distance coefficient kn _{+ 1} vF ₂ (kn _{+ 1} ): Voltage amplitude corresponding to the assumed end-of-life accident point rotation vector change at the distance coefficient kn _{+ 1}

  When the above equations (32) and (33) are satisfied, it can be seen that there is an intersection between both curves. In this case, the distance coefficient corresponding to the accident point can be calculated based on the following equation, for example.

Equation (34) means that the midpoint of the distance coefficient before and after the two curves intersect is the distance coefficient corresponding to the accident point, and the distance coefficient corresponding to the accident point is obtained without obtaining the intersection of both curves. Since it can be calculated, accident location can be simplified. In the process of the present embodiment, the processes of steps S120 and S121 are added to increase the accuracy of the assumed accident. That is, if the two curves have the intersection (step S118, Yes), increments the value of the matching count M (step S120), until the verification number M reaches a predetermined set value M _{The set} (step S121), the process Repeatedly. A numerical value such as 3 is selected as the _set value M _set .

  If the number M of collations is changed and the determination process is performed again (No at Step S121), the sampling point designation variable P is incremented (Step S102), and the processes at Steps S103 to S120 are repeated.

For example, if the processing when M = 1 uses data with a sampling phase of 30 degrees, data with a sampling phase of 60 degrees (when N = 3) is used with M = 2, and with M = 3, Data with a sampling phase of 90 degrees (when N = 3) is used. In the case where the _set value M _set = 3, in all these sampling phases, when the condition of step S118 is satisfied, the process proceeds to step S122.

  On the other hand, when at least one of the above formulas (32) and (33) is not satisfied (step S118, No), the number M of collations is reset (step S119), and the processes of steps S103 to S120 are executed again.

(Step S122)
In step S122, the distance coefficient k is optimized. This process is a process for increasing the accuracy of locating the distance coefficient corresponding to the accident point. In this optimization process, it is considered several approaches, for example, and sets the interval _{[k n, k n + 1} ] to both ends distance coefficient before and after the intersection of the two curves to a new variable range, What is necessary is just to repeat the determination process whether there exists an intersection of both curves, reducing the increment range of the distance coefficient performed by following Formula.

In the present flow, as shown in step S 111, S113, S114, the value of the distance coefficient k varying from k _min to k _max, so as to vary in increments (k _min -k _max) / 100 ing.

For example k _min = 0 km, if k _max = 100km, increment value is 1km wide, it is possible to orientation the fault point at 1km wide. Also, for example, when the assumed fault point is estimated to be between 80km from local end (k _n = 80km) and _{90km (k n + 1 = 90km} ), for example, _{k min = k n = 80km,} k max = If k _{n + 1} = 90 km is set (changed), the increment value becomes 0.1 km (100 m), and the accident point can be standardized with a width of 100 m. If this process is repeated as appropriate according to the measurement accuracy or the like, the location accuracy of the accident point can be increased.

  Next, regarding the transmission line accident point location apparatus according to the present embodiment, the concept of the accident point location calculation when the transmission line has a branch line will be described with reference to the drawing of FIG. Here, FIG. 7 is a diagram showing an equivalent circuit for the rotation vector change when the power transmission line has a branch line.

In FIG. 7, the meaning of each symbol is as follows.
M: local end bus N: remote end generatrix Z _M: M bus backward impedance Z _N: N bus backward impedance F: fault point Z _1: impedance between the branch point 1 and the branch point 2 (known)
Z ₁₁ : Impedance between M bus and branch point 1 (known)
Z ₁₂ : Branch impedance at branch point 1 (known)
Z ₂₁ : Impedance between N bus and branch point 2 (known)
Z ₂₂ : Branch impedance at branch point 2 (known)
Δv _M : Rotational vector change voltage measured by own end (known)
.Delta.i _M: rotation vector variation current measured by the own end (known)
ΔV _N : Rotational vector change voltage measured by the other end (known)
Δi _N : rotation vector change current measured by the other end (known)
Δv ₁ : rotation vector change voltage at branch point 1 Δi ₁ : rotation vector change current at branch point 1 Δv ₂ : rotation vector change voltage at branch point 2 Δi ₂ : rotation vector change current at branch point 2

  Here, the rotation vector change voltage and the rotation vector change current at the branch point 1 in FIG. 7 are respectively expressed by the following equations.

  Similarly, the rotation vector change voltage and the rotation vector change current at the branch point 2 in FIG. 7 are also expressed by the following equations, respectively.

  In FIG. 7, the equivalent circuit between the branch point 1 and the branch point 2 is equivalent to the equivalent circuit diagram shown in FIG. Therefore, by applying the above-described method, it is possible to perform an accident point location calculation process when there is a branch line.

  In FIG. 7, the case where there are two branch lines is shown as an example, but it goes without saying that the above method can be applied to a case where the number of branch lines is one or three or more.

(simulation result)
Next, simulation results performed on the power transmission line accident point location apparatus according to the present embodiment will be described with reference to FIGS. 8 to 14.

  FIG. 8 is a diagram showing a typical IEEJ EAST10 model system (50 Hz system) in Japan. Numbers in parentheses indicate node numbers, and numbers in <> indicate branch numbers. Now, in this model system, it is assumed that the power transmission line fault location device is arranged at the node 21, and the AB phase of the single power transmission line is located at a distance A of 40% from the node 21 of the double power transmission line from the node 21 to the node 11. Cause a short circuit accident. At this time, it is assumed that a fault location simulation is performed using the voltage / current measured at the node 21 (own end) and the node 11 (mating end).

  FIG. 9 is a diagram showing a self-end three-phase voltage waveform in this simulation. In addition, this three-phase voltage waveform is a thing at the arrangement | positioning end (own end) where the power transmission line accident point location apparatus is arrange | positioned. In this simulation, an AB phase short-circuit accident has occurred, so as shown in FIG. 9, in each voltage waveform measured at the node 21, the A phase (solid line) · The voltage of the B phase (broken line) is small.

  FIG. 10 is a diagram illustrating a self-end three-phase current waveform in this simulation. In addition, this three-phase current waveform is a thing at the arrangement | positioning end (own end) where the power transmission line accident point location apparatus is arrange | positioned. In this simulation, an AB phase short-circuit accident has occurred, so as shown in FIG. 10, in each current waveform measured at the node 21, the A phase (solid line) · The B phase (broken line) current is large.

  FIG. 11 is a diagram showing a counterpart three-phase voltage waveform in this simulation. In addition, this three-phase voltage waveform is a thing at the arrangement | positioning end (partner end) where the power transmission line accident point location apparatus is arrange | positioned. In this simulation, an AB phase short-circuit accident occurs, so as shown in FIG. 11, in each voltage waveform measured at node 11, the A phase (solid line) · The voltage of the B phase (broken line) is small.

  FIG. 12 is a diagram illustrating a counterpart three-phase current waveform in this simulation. In addition, this three-phase voltage waveform is a thing at the arrangement | positioning end (partner end) where the power transmission line accident point location apparatus is arrange | positioned. In this simulation, an AB phase short-circuit accident has occurred, so as shown in FIG. 12, in each current waveform measured at node 11, the A phase (solid line) The B phase (broken line) current is large.

  FIG. 13 is a diagram showing an accident starting voltage waveform in this simulation. As shown in the waveform of the solid line portion in FIG. 13, during the period of 3/4 cycle (15 ms) immediately after the accident, the AB phase rotation vector change activation voltage amplitude is the AB phase rotation vector activation one cycle before the accident. It is larger than the voltage amplitude, and it can be seen that the accident has been activated.

FIG. 14 is a diagram showing an assumed accident point convergence calculation waveform in this simulation. In FIG. 10, the waveform indicated by the solid thick solid line is the voltage amplitude (vF ₁ ) of the assumed end accident point rotation vector change, and the waveform indicated by the thin solid line is the voltage amplitude (vF ₂ ) of the assumed end accident point rotation vector change. It is. Each amplitude value is an assumed accident point convergence calculation diagram at a half cycle (10 ms) after the occurrence of the accident.

According to the waveform of FIG. 14, the self-contained accident point rotation vector variation voltage amplitude (vF ₁ ) and the partner end conceivable accident point rotation vector variation voltage amplitude (vF ₂ ) intersect at k = 40%. The accident points are correctly located.

  In FIG. 14, the voltage amplitude corresponding to the accident point rotation vector change corresponding to the accident point that is the intersection of both curves (the same applies to the voltage amplitude corresponding to the other end assumed accident point rotation vector change) is the accident at the accident point. It corresponds to the previous voltage amplitude (voltage amplitude before the accident at the accident point). This fact is not a coincidence and proves that the equivalent circuit for the rotation vector change is correct.

In addition, when there is an accident point resistance, the waveforms of the assumed accident point rotation vector change voltage amplitude (vF ₁ ) and the counterpart assumed accident point rotation vector change voltage amplitude (vF ₂ ) are symmetrically up and down. To do. Therefore, it can be seen that the power transmission line accident point locating device of the present embodiment in which the intersection of both curves is the fault point is not affected by the fault point resistance.

  As described above, according to the transmission line accident point location apparatus according to the present embodiment, the self-end voltage rotation vector change amount, the self-end current rotation vector change amount, and a predetermined distance away from the self-end side measurement point. Using the second impedance to the assumed point that is a virtual point on the transmission line, the voltage of the own assumed accident point rotation vector change voltage calculated as the rotation vector change voltage when it is assumed that an accident has occurred at the assumed point When it is assumed that an accident occurred at the assumed point using the amplitude value, the other end voltage rotation vector change, the other end current rotation vector change, and the third impedance from the opposite end measurement point to the assumed point Since the fault point is determined based on the amplitude value of the voltage at the other end of the assumed accident point rotation vector calculated as the rotation vector change voltage, the fault point resistance Can do orientation that no receive the sound, it is possible to highly accurate orientation of the accident point in the transmission line.

  Moreover, according to the transmission line accident point location apparatus according to the present embodiment, when there is one or more branch lines on the transmission line, the rotation vector change voltage at the branch point from the transmission line of the branch line is calculated as the self-end voltage. Applying the rotation vector change amount or the other end voltage rotation vector change amount and applying the rotation vector change current at the branch point as the own end current rotation vector change amount or the opposite end current rotation vector change amount, And a branch point between the other end and the branch point, or a branch point of one branch line and a branch point of another branch line adjacent to the one branch line Since it is possible to determine the accident point during the period, even if there is a branch line in the transmission line, highly accurate accident point localization calculation is possible.

  In the present embodiment, a calculation formula for a short-circuit accident has been used for the sake of brevity. Moreover, the simulation result has also demonstrated the short circuit accident between AB phases as an example. However, the power transmission line accident location system according to the present embodiment is not limited to the case of a short circuit accident. By using the same concept and procedure as the above-described method and the calculation formula of the ground fault in the spiral vector theory, it is possible to configure a power transmission line fault location device that can be applied to the ground fault.

  As described above, the transmission line accident point location device according to the present invention can be applied to a transmission line having a branch line, and is useful as a transmission line accident point location device that enables highly accurate accident point location accuracy. It is.

It is a figure which shows the structure of the power transmission line accident point location apparatus concerning embodiment of this invention. It is a flowchart which shows operation | movement of a power transmission line accident point location apparatus. It is the figure which modeled the electric power system which is a target of the power transmission line accident point location apparatus concerning this Embodiment. FIG. 4 is an equivalent circuit diagram in which the circuit of FIG. It is an equivalent circuit diagram which shows the concept of the calculation process of an assumed accident point. It is a figure which shows the concept of the calculation process of the distance coefficient k corresponding to an accident point. It is a figure which shows a rotation vector change part equivalent circuit in case a transmission line has a branch line. It is a figure which shows a typical electrical society EAST10 model system | strain (50Hz system | strain) in Japan. It is a figure which shows the self-end three-phase voltage waveform in simulation. It is a figure which shows the self-end three-phase current waveform in simulation. It is a figure which shows the other party three-phase voltage waveform in simulation. It is a figure which shows the other party end three-phase current waveform in simulation. It is a figure which shows the accident starting voltage waveform in simulation. It is a figure which shows the assumption accident point convergence calculation waveform in simulation.

Explanation of symbols

1 Transmission line accident location system (self-end equipment)
2 Self-end voltage / current measurement / A / D conversion section 3 Self-end voltage rotation vector change calculation section (first calculation section)
4. Self-end current rotation vector change calculation unit (second calculation unit)
5 Self-rotation vector starting voltage calculation unit (third calculation unit)
6 Self-rotation vector change amount start voltage calculation unit (fourth calculation unit)
7 Self-end area accident determination part 8 Counterpart voltage / current time-series data receiving part 9 Counterpart voltage rotation vector change calculation part (fifth calculation part)
10. Counterpart current rotation vector change calculation unit (sixth calculation unit)
DESCRIPTION OF SYMBOLS 11 Accident point calculation part 12 Interface 13 Memory | storage part 14 Remote transmission part 15 Transmission line accident point location apparatus (partner end apparatus)

Claims (11)

Transmission line fault point locating device that uses a rotation vector change equivalent circuit that includes a change in voltage rotation vector, a change in current rotation vector, and a rotation vector starting voltage as elements. In
Based on the self-end voltage instantaneous value data measured on the self-end side of the power transmission line, a change in the self-end voltage rotation vector, which is a change in the voltage rotation vector on the self-end side of the rotation vector change equivalent circuit, A first calculation unit for calculating;
Based on the instantaneous current value data measured at the self-end side of the transmission line, the change in the self-end current rotation vector, which is the change in the current rotation vector on the self-end side of the rotation vector change equivalent circuit, A second calculation unit for calculating;
Using the first-end voltage rotation vector change, the own-end current rotation vector change, and the first impedance from the own end to the other end of the transmission line on the own end side of the rotation vector change equivalent circuit A third calculation unit for calculating a self-end rotation vector start-up voltage that is the rotation vector start-up voltage; and a fourth calculation unit for calculating a self-end rotation vector start-up voltage change that is a change in the self-end rotation vector start-up voltage. When,
The other end voltage rotation vector which is the change of the voltage rotation vector on the other end side of the rotation vector variation equivalent circuit based on the other end voltage instantaneous value data measured at the other end and transmitted to the other end side A fifth calculation unit for calculating a change amount;
The other end current rotation vector which is a change amount of the current rotation vector on the other end side of the rotation vector variation equivalent circuit based on the other end current instantaneous value data measured at the other end and transmitted to the other end side. A sixth calculation unit for calculating a change amount;
Using the second impedance to the assumed point that is a virtual point on the transmission line that is a predetermined distance away from the measurement point on the own end side, and the change in the own end voltage rotation vector, the own end current rotation vector change, and Thus, the amplitude value of the assumed end failure point rotation vector change voltage calculated as the rotation vector change voltage when it is assumed that an accident has occurred at the assumed point, the opposite end voltage rotation vector change amount, the opposite end current The other end calculated as the rotation vector change voltage when it is assumed that an accident has occurred at the assumed point using the rotation vector change amount and the third impedance from the measurement point on the opposite end side to the assumed point An accident point calculation unit for locating the accident point based on the amplitude value of the assumed accident point rotation vector change component voltage;
A transmission line accident location system characterized by comprising:   The accident point calculation unit includes a first curve representing a change in an amplitude value of the own-end assumed accident point rotation vector change voltage and a first curve representing a change in the amplitude value of the counterpart-end assumed accident point rotation vector change voltage. The transmission line accident point locating device according to claim 1, wherein an intersection point with the curve of 2 is determined as an accident point.   The accident point calculation unit includes a first curve representing a change in an amplitude value of the own-end assumed accident point rotation vector change voltage and a first curve representing a change in the amplitude value of the counterpart-end assumed accident point rotation vector change voltage. The transmission line accident point locating device according to claim 1, wherein an average value of distance coefficients before and after the intersection of the two curves is determined as an accident point. Based on the amplitude value of the self-end rotation vector starting voltage and the amplitude value of the self-end rotation vector change amount starting voltage, a city accident determination unit for determining the presence or absence of an accident in a protected area,
The said accident point calculation part performs the calculation process regarding accident point location, when the said accident determination part in a city discriminate | determines that there exists an accident in a city, The any one of Claims 1-3 characterized by the above-mentioned. Power line accident location system. When there are one or more branch lines on the transmission line,
Applying the rotation vector change voltage at the branch point of the branch line from the power transmission line as the local voltage rotation vector change or the counterpart voltage rotation vector change, and the rotation vector change current at the branch point By applying the change in the own end current rotation vector or the other end current rotation vector change, an accident point between the own end and the branch point, an accident point between the counterpart end and the branch point Or an accident point between a branch point of one branch line and a branch point of another branch line adjacent to the one branch line is determined. Transmission line accident location system as described in the section. The number of collations for performing the calculation process for locating the accident point multiple times is set,
The said accident point calculating part performs the said calculation process based on the measured voltage and measured current which were sampled by the different sample point for the said collation frequency, The any one of Claims 1-5 characterized by the above-mentioned. Transmission line accident location system.   The accident point calculation unit, when determining the accident point, narrows the variable range of the assumed point and narrows the variable range of the assumed point to be small. Transmission line accident location system as described in the section. Transmission line fault location method for locating the fault point in the target power transmission line using a rotation vector change equivalent circuit including the change of the voltage rotation vector, the change of the current rotation vector, and the rotation vector starting voltage as elements. In
Based on the instantaneous voltage instantaneous value data on the local end side of the transmission line, a first-end voltage rotation vector change that is a change in the voltage rotation vector on the local end side of the rotation vector variation equivalent circuit is calculated. Steps,
A second step of calculating a self-current current rotation vector change that is a change of the current rotation vector on the self-end side of the rotation vector change equivalent circuit based on the self-end current instantaneous value data on the self-end side;
Using the first-end voltage rotation vector change, the own-end current rotation vector change, and the first impedance from the own end to the other end of the transmission line on the own end side of the rotation vector change equivalent circuit A third step of calculating a self-end rotation vector start-up voltage that is the rotation vector start-up voltage; a fourth step of calculating a self-end rotation vector start-up voltage change that is a change in the self-end rotation vector start-up voltage;
Based on the other end voltage instantaneous value data on the other end side of the power transmission line, a fifth change of the other end voltage rotation vector that is a change of the voltage rotation vector on the other end side of the rotation vector change equivalent circuit is calculated. Steps,
A sixth step of calculating a change amount of the other end current rotation vector, which is a change amount of the current rotation vector on the opposite end side of the rotation vector change equivalent circuit, based on the opposite end current instantaneous value data on the own end side;
Using the second impedance to the assumed point which is a virtual point on the power transmission line that is a predetermined distance away from the measurement point on the own end side, and the change in the own end voltage rotation vector, the own end current rotation vector change The amplitude value of the assumed end point accident point rotation vector change voltage calculated as the rotation vector change amount voltage when it is assumed that an accident has occurred at the assumed point, the opposite end voltage rotation vector change amount, the opposite end current rotation The other end assumed accident calculated as the rotation vector change amount voltage when assuming that the accident occurred at the assumed point using the third impedance from the measurement point on the opposite end side to the assumed point using the vector change amount A seventh step of locating the accident point based on the amplitude value of the point rotation vector change component voltage;
A transmission line accident location method characterized by including.   In the seventh step, a first curve representing a change in the amplitude value of the own end assumed accident point rotation vector change voltage and a second curve representing a change in the amplitude value of the other end assumed accident point rotation vector change voltage. The transmission line accident point locating method according to claim 8, wherein a process of determining an intersection with a curve as an accident point is performed.   In the seventh step, a first curve representing a change in the amplitude value of the own end assumed accident point rotation vector change voltage and a second curve representing a change in the amplitude value of the counterpart end assumed accident point rotation vector change voltage. 9. The transmission line accident point location method according to claim 8, wherein a process of determining an average value of distance coefficients before and after intersecting with the curve as an accident point is performed. When there are one or more branch lines on the transmission line,
Applying the rotation vector change voltage at the branch point of the branch line from the power transmission line as the local voltage rotation vector change or the counterpart voltage rotation vector change, and the rotation vector change current at the branch point By applying the change in the own end current rotation vector or the other end current rotation vector change, an accident point between the own end and the branch point, an accident point between the counterpart end and the branch point Or an accident point between a branch point of one branch line and a branch point of another branch line adjacent to the one branch line is determined. Transmission line accident location method described in the section.

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