JP5834308B2 - Line constant measuring method and protection control measuring device for two parallel transmission lines - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method for estimating a line constant of a transmission line using the amount of electricity taken in a protection control measurement apparatus installed at both terminals of a parallel two-line transmission line, and a protection control measurement apparatus incorporating the same. It is.

  Obtaining accurate line constants is important for protection relay setting, fault location, and system operation. Many methods have been proposed for this purpose. The Carson-Polarczhek method, which is often used, is a computer that inputs various parameters such as the geometric structure of the track and the distance from the ground. However, this method has a problem that a large number of parameters are required, labor for matching the presence / absence of a bridge and the presence / absence of each phase with an actual transmission line is great, and the accuracy is sometimes low.

  As another method, a test voltage is input for each phase when a transmission line is constructed, and the impedance and admittance are obtained from the current voltage at that time. Although this method can accurately determine the line constant, it requires labor and cost, requires measurement when the line is stopped, and requires higher test voltage to increase measurement accuracy. There are also safety issues.

  In order to solve the problems of the Carson-Polarczhek method and the method of applying the test voltage described above, the voltage current at both ends of the transmission line at the same time is obtained using GPS, and the transmission line constant is obtained from this. The following proposals have been made to use it for accident location.

JP 2003-270285 A JP 2004-12292 A

“Method for calculating line constants of unbalanced parallel two-line transmission lines for fault location”: Announcement of the 2010 IEEJ National Conference

  In the methods proposed in these documents, the transmission line is modeled as a lumped constant circuit or a distributed constant circuit, and the line constant is obtained from the voltage and current at both ends at the time of the transmission line fault.

  The techniques introduced in Patent Documents 1 and 2 above are methods for obtaining a line constant for fault point location of a transmission line, on the condition that an accident occurs inside the corresponding transmission line, The relationship between line constants is formulated. Therefore, the line constant of the corresponding transmission line cannot be obtained unless a transmission line internal accident occurs.

  This is not appropriate when line constants are required to determine the distance relay settling value. This is because an accurate line constant is required at the time of occurrence of a system fault. In addition, it is also inconvenient when it is used for system operation in general, for example, estimation of tidal currents, because the line constant cannot be obtained if a power line internal accident does not occur.

  The present invention has been made in view of the above circumstances, and in a parallel two-line transmission line, a line constant measurement method capable of easily and accurately obtaining a transmission line constant, and a protection control measurement apparatus incorporating the same. It is intended to provide. In particular, the present invention does not necessarily require a power line internal accident as in the inventions described in Patent Document 1 and Patent Document 2, and can obtain a line constant with high accuracy using a normal power flow. It is an object of the present invention to provide a typical line constant measuring method and protection control measuring device.

The present invention relates to a line constant measuring method for measuring a constant of a parallel two-line transmission line in which the line has no branching and the first transmission line and the second transmission line are symmetrically arranged on the left and right of the steel tower. It is characterized by performing.
(1) For each of the parallel two-line transmission lines, the amount of electricity taken in at least two different times in steady operation and the amount of electricity of the zero-phase component at least one time point are input to the line constant calculation means. .
(2) In the line constant calculation means, when all the phase arrangements of the first transmission line and the second transmission line match, the common line condition is a zero-phase voltage, and the differential line condition is a defect including the a phase. On the basis of the conditions for the open phase including the phase and the b phase and the open phase including the c phase, and the equations shown in Equations 3, 4, and 6,
When all the phase arrangements of the first transmission line and the second transmission line are inconsistent, the common line condition is a zero-phase voltage, and the differential line condition is an open phase including any one of a, b, and c. Based on the conditions to be performed and the equations shown in Equations 3, 4, and 6,
When the phase arrangement of only one phase is the same among all the phase arrangements of the first transmission line and the second transmission line, the common line condition is the open phase including the zero-phase voltage and the a or c phase, and the differential line Based on the condition that the phase is an open phase including the a or c phase and the open phase including the c phase, and the equations shown in the equations (3), (4), and (6) The line constant calculated as two single-line transmission line models is restored to the parallel two-line transmission line model by mode synthesis, and the parallel two-line transmission line Calculate the line constant.

In addition, the protection control measuring device of the present invention has both ends of a parallel two-line power transmission line in which the circuit is not branched and the first power transmission line and the second power transmission line are symmetrically arranged on the left and right of the steel tower. An electric quantity capturing means for capturing the electric quantity at both ends of the transmission line installed in the power supply, a time synchronization means for performing the electric quantity capturing in the electric quantity capturing means at the same time, and the line as a π-type equivalent circuit or a distributed constant As a circuit, the constant of the line is calculated from the electric quantity including the electric quantity of the zero-phase component at at least one time taken in by the electric quantity taking-in means, and all the phase arrangements of the first transmission line and the second transmission line are arranged. , The common line condition is a zero-phase voltage, the differential line condition is an open phase including an a phase, an open phase including a b phase, and an open phase including a c phase. And based on the equation shown in Equation 6
When all the phase arrangements of the first transmission line and the second transmission line are inconsistent, the common line condition is a zero-phase voltage, and the differential line condition is an open phase including any one of a, b, and c. Based on the conditions to be performed and the equations shown in Equations 3, 4, and 6,
When the phase arrangement of only one phase is the same among all the phase arrangements of the first transmission line and the second transmission line, the common line condition is the open phase including the zero-phase voltage and the a or c phase, and the differential line Line constant calculating means for calculating as an admittance and impedance matrix based on the condition that the condition is an open phase including the a or c phase and the open phase including the c phase, and the equations shown in the equations (3), (4), and (6) Is provided.

In particular, the line constant calculating means has the following configuration.
(1) One-line transmission line modeling processing unit that mode-divides parallel two-line transmission lines into common mode and differential mode.
(2) A one-line transmission line model line constant calculation processing unit that calculates a line constant for each of the two one-line transmission line models.
(3) A two-line transmission line model restoration processing unit for restoring line constants calculated as two one-line transmission line models into a parallel two-line transmission line model by mode synthesis.

  According to the present invention, in a parallel two-line transmission line, the amount of electricity including the zero phase component is taken in at both ends of the line to be measured at the same time, and the line constant is calculated as an admittance and impedance matrix based on the amount of electricity. As compared with the prior art, the line constant can be obtained easily and accurately. In particular, detection of the zero-phase component is not necessarily limited to an accident inside the transmission line, and can be detected. Therefore, according to the present invention, it is possible to easily calculate the line constant other than at the time of the accident.

1 is a layout diagram showing the overall configuration of Embodiment 1 of the present invention. FIG. 3 is a front view illustrating an example of arrangement of power transmission lines in the first embodiment. 1 is a block diagram showing an internal configuration of a protection control measurement device in Embodiment 1. FIG. 3 is a flowchart for explaining the operation of the first embodiment. 9 is a flowchart for explaining the operation of the second embodiment. 10 is a flowchart for explaining the operation of the third embodiment. The block diagram of the protection control measuring device in Example 4. FIG. The wave form diagram which shows the voltage current waveform at the time of the accident of Example 4. FIG. 10 is a flowchart for explaining the operation of the fourth embodiment. FIG. 10 is a block diagram of a protection control measurement device according to a fifth embodiment. 10 is a flowchart for explaining the operation of the fifth embodiment. FIG. 10 is a block diagram of a protection control measurement device according to a sixth embodiment. 10 is a flowchart for explaining the operation of the sixth embodiment. FIG. 10 is a block diagram of a protection control measurement device according to a seventh embodiment. 10 is a flowchart for explaining the operation of the seventh embodiment. FIG. 10 is a block diagram of a protection control measurement device according to an eighth embodiment. 10 is a flowchart for explaining the operation of the eighth embodiment.

  Embodiments of the present invention will be described according to the following examples.

(Constitution)
FIG. 1 is a layout diagram illustrating the overall configuration of a protection control measurement device 110 incorporating a transmission line constant measurement method according to a first embodiment. Reference numerals 101A, 101B, and 101C denote first constant constant measurement transmission lines, and 102A, 102B, and 102C denote second constant measurement power transmission lines. Reference numerals 1031 and 1032 denote current transformers, and 1041 and 1042 denote instrument transformers. Reference numeral 105 denotes a communication line that connects the protection control measuring devices of the A and B electric stations. As shown in FIG. 2, the transmission lines of the first constant measurement transmission line 1 and the second constant measurement transmission line 2 are arranged symmetrically on the left and right of the steel tower.

  The internal configuration of the protection control measuring device 110 is shown in FIG. The protection control measuring device 110 provided at each of the electric stations A and B is an electric device that samples instantaneous values of currents and voltages at both ends of the transmission lines 101A, 101B, 101C and 102A, 102B, 102C in an operating state at regular intervals. A quantity taking-in means 111 is provided. The electric quantity taking-in means 111 converts the taken-in electric quantity into a digital signal and records it in a memory.

  Time information from the time synchronizer 112 using the GPS absolute time signal is also input to the electric quantity take-in means 111. That is, in order to measure the constants of the first and second constant-measurement transmission lines 1 and 2, it is necessary to sample data at the same time in the devices 110 at both ends of each transmission line. Therefore, in the protection control measuring devices 110 at both ends, the time of the internal clock is adjusted with high accuracy using the time synchronization means 112 based on the absolute time signal of GPS. In accordance with this clock, the protection control measuring device 110 samples instantaneous values of current and voltage at both ends of the transmission line at regular time intervals.

  The current and voltage data at both ends of the transmission line recorded in the memory in the electric quantity capturing unit 111 are calculated by a two-line transmission line line constant calculation unit 113 (hereinafter referred to as a line constant calculation unit) according to a method described later. The current and voltage of the counterpart terminal enter the self-quantity taking-in means 111 of the own terminal using the communication line 105.

  The line constant calculation unit 113 obtains an admittance matrix and an impedance matrix when the zero-phase component is included in the current and voltage at at least one time point. Therefore, the protection control measuring device 110 includes a zero phase detection means 114. That is, as described in Non-Patent Document 1, at least three measurements are required to obtain the line constant of an unbalanced two-line transmission line, and data with conditions as shown in the table below is required. I already know that.

  Thus, in order to obtain the line constant of the parallel two-line transmission line, the zero-phase component of the current and voltage at at least one time point is required. Therefore, in this embodiment, the zero phase detection means 114 is incorporated in the protection control measurement device 110.

Further, in the present embodiment, the line constant calculation means 113 includes the following three means.
(1) One-line transmission line modeling processing unit that mode-divides parallel two-line transmission lines into common mode and differential mode
(2) One-line transmission line model line constant calculation processing unit for calculating the line constant for each of the two one-line transmission line models
(3) Two-line transmission line model restoration processing unit that restores line constants calculated as two single-line transmission line models to parallel two-line transmission line models by mode synthesis

(Function)
Next, the operation of this embodiment will be described. First, in step S1, the amount of electricity at time t1 is captured. Since the amount of electricity does not need to include the zero phase component, it may be the amount of electricity taken at an arbitrary time. Next, in step S2, it is monitored whether a voltage or current including the zero phase is generated.

  Specifically, it can be realized by providing a zero-phase overvoltage relay or a zero-phase overcurrent relay used in power system protection in the apparatus and confirming the operation. If the zero-phase component occurs, for example, due to an accident outside or inside the transmission line, these relays move, and the amount of electricity is taken in at time t2 at that time in step S3. Thereby, the admittance matrix can be obtained. Further, in order to obtain the impedance matrix, the electric quantity is taken in at step S4 at an appropriate time t3, and the line constant is calculated in step S5 using all the electric quantities obtained from the above.

  Since the electric quantity is accurately taken in at the timing when the zero phase component is generated in the power system, the calculation accuracy of the line constant can be further improved.

  In the same manner, the amount of electricity is taken in the same manner up to step Sn (n ≧ 2). Finally, in step Sn + 1, the admittance and impedance matrix are obtained by the line constant calculation means 113.

That is, in step Sn + 1, the three processing units (1) to (3) provided in the line constant calculating unit 113
(1) One-line transmission line modeling process,
(2) Single line transmission line model line constant calculation processing,
(3) Two-line transmission line model restoration processing,
Are obtained in order to obtain unknowns of the self-impedances Ys and Zs and the mutual impedances Ym and Zm. Hereinafter, these processes will be described.

(1) One-line transmission line modeling process As shown in FIG. 2, the line constants of transmission lines 1L and 2L are completely independent from the reciprocity and physical symmetry of the transmission line arrangement of parallel two-line transmission lines. The impedance Z = R + jX (Ω / km) and the admittance Y = jB (Ω−1 / km) are not expressed by the following equations.

The quantity of electricity at both ends of the parallel two-line transmission line in the above figure is defined by the following vector.

If the property that the power transmission lines 1L and 2L are symmetrical is used in order to obtain the line constant of the parallel two-line power transmission line, the following mode decomposition matrix is derived.

Here, U is a 3 × 3 unit matrix. When the mode decomposition calculation by T-1 is applied to Y and Z, the following equations are obtained.

  From this result, the parallel two-line transmission line is separated into two virtual one-line transmission lines (referred to as common line and differential line) as shown below by mode decomposition (common mode and differential mode) using T-1. can do.

  From the above, the problem of obtaining the self-impedances Ys and Zs and the mutual impedances Ym and Zm of the two-line transmission lines can be reduced to the problem of obtaining the line constants of the two one-line transmission lines.

(2) Single-line transmission line model line constant calculation processing Various means can be adopted to calculate the line constant of this single-line transmission line model. Various line constant calculating means will be specifically described in the second and subsequent embodiments.

(3) Two-line transmission line model reconstruction processing YcL, ZcL and YdL, ZdL obtained by equation (B) are mode-combined by the following equation to obtain impedances Y and Z of the original two-line transmission line be able to.

(effect)
In the present invention, the amount of electricity at a plurality of points in time when the transmission line is operated in this way is taken in, and the two-line transmission line is regarded as two virtual one-line transmission lines as described above. Thus, the line constant can be calculated. As a result, by replacing the parallel two-line transmission line with two single-line transmission line models virtually, the line constant of the two-line transmission line is calculated by the same means as the line constant calculation means of the one-line transmission line. It becomes possible to do.

(Constitution)
In the configuration of the first embodiment, a method for considering a transmission line as a π-type equivalent circuit model when performing a line constant calculation process of a one-line transmission line model will be described. Here, it is assumed that the transmission line is not suspended. Of course, the general solution obtained below also applies to the case where it is suspended.

(Function)
FIG. 5 shows a processing flow of the second embodiment. That is, in step Sn + 1 of FIG. 4, in calculating the line constant of (2), a π-type equivalent circuit model is applied as a one-line transmission line model for calculating the line constant.

In this case, the relationship between the current and voltage at both ends of the transmission line can be expressed as follows.

However, each matrix shall satisfy the following.

  When voltage and current data as shown in the table above are obtained, the following line constants (D) and (E) can be calculated by the line constant calculation means to obtain cL and dL line constants. The entire line constant is obtained.

(effect)
The method of considering a transmission line as a π-type equivalent circuit model can be applied to a parallel two-line transmission line, and a settling calculation related to the transmission line required for a protection control measurement device installed on a conventional two-line transmission line can be performed. Significant labor saving.

(Constitution)
As a third embodiment, a method of considering a power transmission line as a distributed constant circuit as described below in the configuration of the first embodiment will be described.

(Function)
In the third embodiment, among the processes described in the first embodiment, the line constant is determined in “(2) Line constant calculation processing of one-line transmission line model” in the line constant calculation processing step Sn + 1 of the one-line transmission line model. A distributed constant circuit model is applied as a one-line transmission line model to be calculated.
FIG. 6 shows a processing flow of the third embodiment.

When a transmission line is a distributed constant circuit, the admittance and impedance per unit length are expressed as follows.

However, it is assumed that the following equation holds.

  In this case, Y and Z can be obtained by using measurement data in two states and solving by the Gauss-Newton method. This procedure is performed by the line constant calculation means 113.

(effect)
In this embodiment, Expression (F) and Expression (G) are applied to Step Sn + 1 “(2) Line Constant Calculation Process for One-Line Transmission Line Model” of the line constant calculation process flow of FIG. As a result, the line constant can be calculated in the same manner as in the second embodiment. As a result, the method of considering the transmission line as a distributed constant circuit model can be applied to the parallel two-line transmission line, and the settling related to the transmission line required in the conventional protection control measuring device installed in the two-line transmission line. The calculation can be saved greatly.

(Constitution)
The configuration of Example 4 is shown in FIG. In contrast to the third embodiment, a transmission line accident state detection unit 115 is provided as a specific example of the zero phase component detection unit 114. Other configurations are the same as those in the first to third embodiments.

  In the fourth embodiment, the circuit breaker is opened by using the transmission line accident state detection means 115, whether an accident has occurred in the target transmission line, the operation of the protection relay that detected the accident, or the system operation. It is detected that it is a period.

  Specifically, an output of a selective relay such as a current differential relay, a distance relay, or a line selection relay that detects an accident inside the transmission line is used as an input of the transmission line accident state detection means 115 to enter the inside of the transmission line. It is possible to detect that an accident has occurred.

(Function)
FIG. 8 shows a time chart of the current-voltage accident waveform in this example. The amount of electricity before the occurrence of the accident at the time t1, the amount of electricity at the time of the occurrence of the accident inside the transmission line at the time t2, the amount of electricity until the circuit breaker opens and recloses the transmission line after the detection of the accident at the time t3, the system at the time t4 Indicates the amount of electricity recovered from the accident.

  An operation flowchart of the present embodiment is shown in FIG. Each step of FIG. 9 will be described in comparison with the amount of electricity at each time shown in FIG. Step S1 in FIG. 9 corresponds to the electric quantity taking in at time t1 before the occurrence of the accident in FIG. 8, and step S1 in FIG. 9 corresponds to electric quantity taking in at the time t1 before the occurrence of the accident in FIG. In step 2, whether or not a power line internal accident has occurred is detected by the power line accident state detection means 115, and when an accident has occurred, the amount of electricity taken in at time t2, which is the time when the accident occurred, in the next step S3. I do.

  Thereafter, in step S4, the amount of electricity is taken in at time t3 until the circuit breaker opens the power transmission line and closes again after the accident is detected. In step 5, the state of the circuit breaker is taken into the apparatus of the present embodiment by the transmission line accident state detection means 115 to determine whether or not the transmission line internal accident is continued or recovered. When it is determined in step 5 that the power line internal accident has been recovered, the amount of electricity at time t4 when the system accident is recovered in step S6 is taken. Thereafter, in step S7, the line constant is calculated using all the electric quantities obtained by the line constant calculating means 113.

(effect)
According to the present embodiment, it is expected that the calculation accuracy of the line constant calculation means is improved because the amount of electricity including the zero-phase component can be used by taking in the amount of electricity during the power line internal accident or recovery. If the line constant can be calculated during a system fault or recovery, the set value of the corresponding protection relay can be changed at that time if the calculation processing speed of the apparatus increases.

(Constitution)
The configuration of Example 5 is shown in FIG. The fifth embodiment is a modification of the first embodiment, and when the line constant calculated by the line constant calculation means 113 is not within a predetermined range, the line constant verification means discards the calculation result. 116 is provided. That is, the line constant calculation unit 113 uses the expressions shown in the first to third embodiments, but the calculation error becomes large depending on the amount of electricity taken in, or the calculation does not converge and the value that is physically impossible is calculated as the calculation result. there's a possibility that. Therefore, in the fifth embodiment, a range of line constants that can be physically present is incorporated in the line constant test means 116 in advance.

(Function)
In the fifth embodiment having such a configuration, the admittance and impedance matrix, which are line constants, are obtained in the same manner as in the first embodiment as in steps 1 to Sn + 1 in the flowchart shown in FIG. Thereafter, in step Sn + 2, the result from the line constant calculation means 113 is input to the line constant verification means 116, and it is verified whether or not the value of the line constant obtained by the calculation is within a preset range. When the test result is within the range, the line constant calculated at step Sn + 3 is determined, and when it is out of the range, the calculation result is discarded at step Sn + 4.

  The line constant calculation process uses the equation shown in the second embodiment or the third embodiment, but the calculation error increases depending on the amount of electricity taken in, or the calculation does not converge and the physically impossible value is calculated. There is a possibility. Therefore, the range of the line constant that can be physically present in advance is incorporated in the line constant test means 116 in advance.

  The result from the line constant verification means 116 is verified, and if it is out of the range, the calculation result is discarded. The admittance and impedance matrix are obtained by the line constant calculating means in step Sn + 1. From the obtained result, the line constant is verified in step Sn + 2, and if it is outside the range of the line constant, the calculation result is discarded.

(effect)
As described above, in the fifth embodiment, calculation errors and calculation results that do not converge can be eliminated, so that a highly accurate line constant can be obtained.

(Constitution)
FIG. 12 shows a configuration of the sixth embodiment in which the protection control measuring device 110 is a power line failure point locating device. That is, a known failure point rating means 117 is incorporated in the protection control measuring device 110 of the present invention, and the line constant obtained by the line constant calculation means 113 is acquired in the failure point rating means 117 by the electric quantity capturing means 111. It is input together with the amount of electricity at each time point.

(Function)
The operation of the sixth embodiment having such a configuration is the same as that of the previous embodiments from step S1 to step Sn + 1 as shown in the flowchart of FIG. Thereafter, the calculation result of the line constant calculation unit 113 in step Sn + 1 is input to the failure point location function 117. In step Sn + 2, the failure point evaluation unit 117 uses the output of the line constant calculation unit 113 to set the set value of the failure point evaluation. Correct or reset.

(effect)
Various fault location algorithms have been proposed, such as those that measure line impedance, such as distance relays, and those that obtain current distribution, all of which require correct line constants.

  In the conventional fault location device, the calculation using the Carson-Polarczhek method described above is performed off-line with a computer to determine the line constant, and is set before the operation of the device is started. After operation, it was common to operate with no settling change. According to the present embodiment, even when the conventional method is set in advance, the line constant is obtained from the actual power flow after operation, and re-setting can be performed automatically, so that a highly accurate fault location device is obtained. be able to.

  In addition, calculation using the conventional Carson-Polarczhek method requires input of the geometrical layout of the line, and input of the ambient temperature, ground conductivity, etc., has to be made by estimation. However, according to this embodiment, it is not necessary to calculate the line constant before starting operation, and the line constant can be reflected while adaptively reflecting changes in the surrounding environment during operation. Therefore, economic efficiency and reliability are greatly improved.

  In addition to the above-mentioned one that takes the current from the other terminal into its own terminal and performs the orientation calculation, the failure point locating device aggregates the time-synchronized electricity quantity data into the central processing unit and calculates Some devices perform fault location calculations. In this case, the line constant calculation unit 113 is placed in the central arithmetic unit, but the effect is equivalent to the above example.

(Constitution)
FIG. 14 shows a configuration of an eighth embodiment in which the protection control measurement device 110 is a distance relay device that protects a transmission line. That is, a known distance relay 118 is incorporated in the protection control measuring device 110 of the present invention, and the line constant obtained by the line constant calculation means 113 is obtained in the distance relay 118 by the electric quantity capturing means 111. It is input with quantity.

(Function)
The operation of the seventh embodiment having such a configuration is the same as that of the previous embodiments from step S1 to step Sn + 1 as shown in the flowchart of FIG. Thereafter, the calculation result of the line constant calculation unit 113 in step Sn + 1 is input to the distance relay 118. In step Sn + 2, the distance relay 118 uses the output of the line constant calculation unit 113 to set a set value related to the line constant of the distance relay 118. Correct or reset.

(effect)
Various distance relay algorithms have been proposed, but all require correct line constants. In conventional distance relays, the calculation using the Carson-Polarczhek method described above to calculate the line constant is performed off-line with a computer, or data measured during construction of the transmission line is used before starting the operation of the equipment. The operating range was set to After operation, it was common to operate with no change of setting. According to the present embodiment, even when the conventional method is set in advance, the line constant is obtained from the actual power flow after the operation and re-settling can be automatically performed, so that a highly accurate distance relay can be obtained. .

  In addition, calculation using the conventional Carson-Polarczhek method requires input of the geometrical layout of the line, and input of the ambient temperature, ground conductivity, etc., has to be made by estimation. However, according to the present example, it is not necessary to calculate the line constant before starting operation, and it is not necessary to prepare the line constant. Since the line constant can be calculated while adaptively reflecting changes in the surrounding environment, the economy and reliability are greatly improved.

(Constitution)
FIG. 16 shows a configuration when the protection control measurement device 110 of the present invention is a current differential relay device that protects a power transmission line. In other words, a current differential relay 119 having a charging current compensation function is incorporated in the protection control measuring device 110 of the present invention, and the line constant obtained by the line constant calculating means 113 for the current differential relay 119 is obtained as an electric quantity. It is input together with the amount of electricity at each time point acquired by the insertion means 111.

(Function)
The operation of the eighth embodiment having such a configuration is the same as that of the previous embodiments from step S1 to step Sn + 1 as shown in the flowchart of FIG. Thereafter, the calculation result of the line constant calculation unit 113 in step Sn + 1 is input to the current differential relay 119. In step Sn + 2, the current differential relay 119 uses the output of the line constant calculation unit 113 to calculate the compensation value of the charging current. Correct or reset.

(effect)
Conventionally, the current differential relay that protects long-distance transmission lines and cable systems is generally set by compensating for the charging current of the transmission line. The charging current is determined from the line admittance and the terminal voltage. I was looking for. The calculation of the admittance has been obtained from the geometrical arrangement of the lines as in the above example, but it has been labor intensive and has a problem in accuracy. According to the present embodiment, even when the current method is set in advance, the charging current is obtained from the actual line admittance after the operation, and the re-setting can be automatically performed. Can be obtained.

  In addition, the calculation using the conventional Carson-Polarczhek method requires economic input because it is necessary to input the geometrical layout of the line and to input the ambient temperature, ground conductivity, etc. There was a reliability issue. Furthermore, preparations such as a power supply for application were also required when actually measuring at the time of construction. According to this embodiment, it is not necessary to calculate the charging current with effort before starting operation, and the line constant can be calculated while adaptively reflecting the surrounding environmental changes during operation. And reliability are improved.

101A, 101B, 101C: Transmission line 1
102A, 102B, 102C: Transmission line 2
1031: Current transformer 1
1032: Current transformer 2
1041: Instrument transformer 1
1042: Instrument transformer 2
105: Communication line 110: Protection control measuring device 111: Electric quantity take-in means 112: Time synchronization means 113: Two-line transmission line line constant calculation means 114: Zero-phase component detection means 115: Transmission line accident state detection means 116: Line Constant test means 117: Fault location means 118: Distance relay 119: Differential relay

Claims (12)

In a line constant measuring method for measuring a constant of a parallel two-line transmission line in which the line has no branch and the first transmission line and the second transmission line are symmetrically arranged on the left and right of the steel tower ,
For each of the two parallel transmission lines, the amount of electricity taken in at least two different time points in steady operation and the amount of electricity in the zero phase component at least one time point are input to the line constant calculation means,
In the line constant calculation means,
When all phase arrangements of the first transmission line and the second transmission line match, the common line condition is a zero-phase voltage, and the differential line condition is an open phase including an a phase and an open phase including a b phase. Based on the conditions for phase loss including the c phase and the equations shown in Equations 15 and 16,
When all the phase arrangements of the first transmission line and the second transmission line are inconsistent, the common line condition is a zero-phase voltage, and the differential line condition is an open phase including any one of a, b, and c. Based on the conditions to be performed and the equations shown in Equations 15 and 16,
When the phase arrangement of only one phase is the same among all the phase arrangements of the first transmission line and the second transmission line, the common line condition is the open phase including the zero-phase voltage and the a or c phase, and the differential line Modal decomposition of parallel two-line transmission lines into common mode and differential mode based on the condition that the phase is an open phase including the a or c phase and the open phase including the c phase, and the equations shown in the equations 15 and 16. By treating the line constants calculated as two single-line transmission line models into a parallel two-line transmission line model by mode synthesis, the line constants of the parallel two-line transmission lines are A line constant measuring method characterized by calculating.
<Mode decomposition>

<Mode composition>

The line constant measuring method according to claim 1, wherein the line constant calculating means uses a π-type equivalent circuit model as a parallel two-line transmission line model, and uses the following equation for calculating the line constant.

2. The line constant measuring method according to claim 1, wherein the line constant calculating means uses a distributed constant circuit model as a transmission line model of two parallel lines, and uses the following equation for calculating the line constant.

The electricity to be measured is installed at both ends of a parallel two-line transmission line in which the first transmission line and the second transmission line are symmetrically arranged on the left and right of the tower without any branching in the line, and the electricity is taken in at both ends of the transmission line A quantity intake means;
A time synchronization means for performing the electric quantity taking-in in the electric quantity taking-in means at the same time;
As the π-type equivalent circuit or distributed constant circuit, the line constant is calculated from the electric quantity including the electric quantity of the zero-phase component at least one time taken in by the electric quantity taking-in means.
When all phase arrangements of the first transmission line and the second transmission line match, the common line condition is a zero-phase voltage, and the differential line condition is an open phase including an a phase and an open phase including a b phase. Based on the conditions for phase loss including the c phase and the equations shown in Equations 19 and 20,
When all the phase arrangements of the first transmission line and the second transmission line are inconsistent, the common line condition is a zero-phase voltage, and the differential line condition is an open phase including any one of a, b, and c. Based on the conditions to be performed and the equations shown in Equations 19 and 20,
When the phase arrangement of only one phase is the same among all the phase arrangements of the first transmission line and the second transmission line, the common line condition is the open phase including the zero-phase voltage and the a or c phase, and the differential line Line constant calculation means for calculating an admittance and an impedance matrix based on the condition that the condition is an open phase including the a or c phase and the open phase including the c phase, and the equations shown in Equations 19 and 20 are provided. In protection control measurement equipment,
The line constant calculating means is
(1) One-line transmission line modeling processing unit that mode-divides parallel two-line transmission lines into common mode and differential mode
(2) One-line transmission line model line constant calculation processing unit for calculating the line constant for each of the two one-line transmission line models
(3) Protection control measurement characterized by a two-line transmission line model restoration processing unit that restores line constants calculated as two single-line transmission line models to parallel two-line transmission line models by mode synthesis apparatus.
<Mode decomposition>

<Mode composition>

The one-line transmission line model line constant calculation processing unit provided in the line constant calculation means uses a π-type equivalent circuit model as a parallel two-line transmission line model, and uses the following equation as the calculation of the line constant calculation means The protection control measuring device according to claim 4 .

The one-line transmission line model line constant calculation processing unit provided in the line constant calculation means uses a distributed constant circuit model as a transmission line model of two parallel lines, and uses the following formula as an operation of the line constant calculation means: The protection control measuring device according to claim 4 , wherein

As the line constant calculating means, provided is a zero phase component detecting means for detecting that the amount of electricity to be taken into the protection control device includes a zero phase component or more, and that the zero phase component becomes a certain value or more. The protection control measuring device according to claim 4 , wherein the line constant calculating means is activated according to a condition. The zero phase component detecting means is composed of a line fault state detecting means for detecting whether a line fault or the line is open, and the electric quantity taking means takes in the electric quantity according to the detection result from the line fault state detecting means. The protection control measuring device according to claim 7 , wherein at least one of the points is a time when a line accident or a line is open. Line constant test means for discarding the calculation result when the line constant calculated by the line constant calculation means is not within a predetermined range is provided on the output side of the line constant calculation means for the two parallel lines. The protection control measuring device according to any one of claims 4 to 7 , A failure point rating means for correcting or resetting a set value related to the line constant in the fault point location based on the calculation result of the line constant calculation means is provided on the output side of the line constant calculation means for the two parallel lines. The protection control measuring device according to any one of claims 4 to 7 . The output side of the line constant calculation means of the two parallel lines, claim 4, characterized in that a distance relay for correcting or resetting the setting value related to the ranging performance by calculating the result of the line constant calculating means The protection control measurement device according to any one of 7 . A transmission line current differential relay for correcting or resetting a set value related to a charging current compensation function based on a calculation result of the line constant calculation unit is provided on an output side of the line constant calculation unit of the two parallel lines. The protection control measuring device according to any one of claims 4 to 7 .

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