JP5481636B2 - Line constant measuring method and protection control measuring device - Google Patents

Description

  The present invention relates to a method for estimating a line constant of a transmission line using an amount of electricity taken in a protection control measurement device installed at both terminals of the transmission line, and a protection control measurement device to which this method is applied.

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 impedance and admittance are obtained from current and 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. Patent Document 1 and Patent Document 2 describe proposals for accident point location.

JP 2003-270285 A JP 2004-12292 A

  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 conventional technology is a method for obtaining the line constant for the fault location of the transmission line, and formulates the relationship between the electric quantity at both ends and the line constant on the condition that an accident occurs inside the transmission line. . 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 an object of the present invention is to provide a line constant measuring method capable of easily and accurately obtaining a transmission line constant, and a protection control measuring apparatus to which this method is applied. To do. 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.

In the line constant measuring method of the present invention, an electric quantity capturing unit that is installed at both ends of a line to be measured and captures an electric quantity at both ends of a transmission line, and an electric quantity is captured by the electric quantity capturing unit at the same time. Time synchronization means, and the line as a π-type equivalent circuit or distributed constant circuit, line constant calculation means for calculating the line constant from the quantity of electricity taken in the quantity of electricity taking means as an admittance and impedance matrix, and Using zero phase detection means for detecting that the amount of electricity to be taken into the electricity quantity taking means contains a zero phase component or more, a zero phase component detected by the zero phase detection means is greater than or equal to a certain value. The line constant calculating means is started on the condition that the electric quantity is taken into the electric quantity taking means at at least two different time points by the line constant calculating means and its zero. And calculates the constants of the power transmission line based on the minute.

  Further, the protection control measuring device of the present invention includes an electric quantity capturing unit that is installed at both ends of the line to be measured and takes in the electric quantity at both ends of the transmission line, and the electric quantity taking in the electric quantity taking unit at the same time. Time synchronization means for performing, and line constant calculation means for calculating the constant of the line as an admittance and impedance matrix from the quantity of electricity taken in by the quantity fetching means as the π-type equivalent circuit or distributed constant circuit A zero phase component detecting means for detecting that the amount of electricity to be taken into the electricity quantity capturing device includes a zero phase component or more, and the line constant calculating means is detected by the zero phase component detecting device. It is started on condition that the zero phase component is equal to or greater than a certain value, and is sent based on the amount of electricity taken into the electricity amount taking means and the zero phase component at at least two different time points. And characterized in that for calculating the constants of the line.

  According to the present invention, it is possible to take in an electric quantity including a zero phase component at both ends of a line to be measured at the same time, and calculate a line constant as an admittance and an impedance matrix based on the electric quantity. Compared with technology, 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. 1 is a block diagram of a protection control measurement device in Embodiment 1. FIG. 3 is a flowchart for explaining the operation of the first embodiment. The block diagram of the protection control measuring device in Example 4. FIG. The wave form diagram which shows the state of the voltage and electric current at the time of a power transmission line accident. 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.

(Constitution)
FIG. 1 is a block diagram of a protection control measurement device 110 to which a transmission line constant measurement method according to Embodiment 1 of the present invention is applied. 101A, 101B, and 101C are constant-measurement transmission lines, 102 is a current transformer, and 103 is an instrument transformer. Reference numeral 104 denotes a communication line connecting the local end and the other end.

  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 includes an electric quantity taking-in means 111 for taking in the electric quantity at the other end and the electric quantity at the other end sent from the counterpart electric station via the communication line. Have Time information from the time synchronization unit 112 using an absolute time signal of GPS is also input to the electric quantity capturing unit 111. On the output side of the electric quantity taking-in means 111, a line constant calculating means 113 for calculating the line constant based on the information obtained by the electric quantity taking-in means 111 is provided.

  The line constant calculation unit 113 obtains an admittance matrix and an impedance matrix when a 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.

  In the protection control measuring apparatus 110 having such a configuration, instantaneous values of currents and voltages at both ends of the transmission lines 101A, 101B, and 101C in an operating state are sampled at a constant time interval by the electric quantity taking-in means 111, and digitally After conversion to a signal, it is recorded in a memory (not shown). In addition, since it is necessary to sample data at the same time in the devices 110 at both ends of the transmission line in order to measure the constant of the transmission line, the time synchronization unit 112 using the absolute time signal of GPS is used to protect both ends. The time of the internal clock of the control measurement device 110 is adjusted with high accuracy.

  In the protection control measurement device 110, the instantaneous values of the current and voltage at both ends of the transmission line are sampled at regular time intervals according to this clock. Next, the current and voltage data at both ends of the transmission line recorded in the memory in the electric quantity taking-in means 111 are calculated by the line constant calculating means 113 according to the following. Here, the current and voltage of the counterpart terminal enter the self-quantity taking-in means 111 of the own terminal using the communication line 104.

The three-phase transmission line model is shown below. In this model, Iia, Iib, Iic, Via, Vib, and Vic are self-quantity, and Ioa, Iob, Ioc, Voa, Vob, and Voc are magnitudes of the other end. Z1, Y1, Z4, Y4, Z6 and Y6 are transmission line self-impedances, and Z2, Y2, Z3, Y3, Z5 and Y5 are mutual impedances.

The following equation (1) is established for the three-phase transmission line in the upper diagram.

  Here, transmission line self-impedances Z1, Y1, Z4, Y4, Z6, Y6 and mutual impedances Z2, Y2, Z3, Y3, Z5, and Y5, which are unknown line constants to be obtained, are currents obtained at both ends of the transmission line, The voltages Vi, Ii, Vo, Io are less than the number of simultaneous equations that are established. Therefore, in the first embodiment, simultaneous equations are formed using currents and voltages at least twice or more, that is, at two different time points, to obtain unknown line constants.

(Function)
Based on the processing flow of FIG. 3, the procedure of taking in the electric quantity and calculating the line constant, which is a feature of the present invention, will be described.

  First, in step S1, the amount of electricity of the own terminal and the counterpart terminal at a certain time t1 is captured. The amount of electricity at the other terminal is captured using a communication line, but since the amount of electricity at time t1 has already been captured at the other terminal by the GPS absolute time signal, the delay of the communication line does not pose a problem. Since the amount of electricity does not need to include the zero phase component in particular, the amount of electricity taken at an arbitrary time may be used.

  Next, in step S2, the zero phase component detecting unit 114 monitors whether a voltage or current including the zero phase component is generated. This zero-phase component detecting means 114 can be realized by providing a zero-phase overvoltage relay or zero-phase overcurrent relay used in power system protection in the apparatus and confirming the operation. If the zero-phase component occurs due to, for example, 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.

  Furthermore, in order to obtain the impedance matrix, the amount of electricity is taken in at step S4 at an appropriate time t3. Thereafter, the taking of these electric quantities is repeated in the same manner until step Sn (n ≧ 2), and the electric quantity at time tn is taken.

  In step Sn + 1, the admittance and impedance matrix are obtained by the line constant calculation means 113. In the present invention, the line constant is calculated by taking in the quantity of electricity at a plurality of points in time when the transmission line is operated in this way.

(Method of calculating line constant)
Hereinafter, a method of calculating the line constant in step Sn + 1 by the line constant calculation unit 113 of the first embodiment will be specifically described. In the first embodiment, the transmission line is considered as a π-type equivalent circuit as described below. 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.

In this π-type equivalent circuit, the line constant is defined by impedance Z (= R + jX [Ω]) and admittance Y (= jB [Ω]). Due to the reciprocity of the circuit, the admittance matrix Y and impedance matrix Z are It is expressed by equation (2).

At this time, the following circuit equation is established for the relationship between the current and voltage at both ends of the transmission line and the above matrix.

If the equation (6) is defined as follows and the equation (3) is an equation for the unknown Y, it is converted into the following equation (7).

This equation (7) can be rewritten as follows.

  Here, mathematical expression processing is performed on the voltage data matrix Vy. Specifically, it transforms into an upper triangular matrix by applying forward erasure in Gaussian elimination. Accordingly, when the rank of the matrix is obtained, it is found that the rank of the matrix Vy is 5 regardless of the values of vi and v0. This indicates that the equation (7) is degenerated and the admittance y cannot be determined with one measurement data.

Hereinafter, the admittance matrix Y is obtained using this matrix V _y . Here, since the admittance y cannot be determined with one measurement data as described above, the measurement data V ⁱ _y and V ⁱⁱ _{y in} two different states are required in this embodiment. In this case, a zero phase component is required in at least one state. That is, when forward erasure is performed on a matrix [V ⁱ _y V ⁱⁱ _y ] ^T in which V ⁱ _y and V ⁱⁱ _y are vertically arranged by an applicable matrix P, the 6 × 6 component is expressed by the following formula ( 9) It becomes (10).

On the other hand, when a specific numerical value is substituted, if Equation (9) does not become 0, the rank of this matrix is 6, and the admittance y can be determined. Here, paying attention to α in equation (10), when V ⁱ _y does not include the zero phase component, the following equation (11) is established. Further, when V ⁱⁱ _y does not include the zero phase component, the following equation (12) is established, and α is 0. Therefore, it can be seen that either V ⁱ _y or V ⁱⁱ _y needs to include the zero phase component.

Thus, when voltage and current data is obtained in a state where the zero phase component is detected by the zero phase component detecting unit 114, the following equation (13) is calculated by the line constant calculating unit 113, The admittance y can be determined, and the admittance matrix Y is obtained.

Similarly, an impedance matrix Z is obtained. That is, similarly to Z, when the equation (4) is changed to an equation for the unknown Z, it is converted into the following equations (14) and (15).

Here, the data I ⁱ _n the three different states in determining the impedance matrix with I _n, is I ⁱⁱ _n and I ⁱⁱⁱ _n becomes necessary. At least one state requires a zero phase component. That is, the rank of I _n is 3, and the rank of the next matrix [I ⁱ _n I ⁱ _n ] ^T using the data of 2 is 5, and the impedance z cannot be determined by the data of 2.

Therefore, data in three different states are used. When forward erasure is performed on the next matrix [I ⁱ _n I ⁱ _n I ⁱ _n ] ^{T in} which data in three states are arranged vertically by an appropriate matrix Q, the 6-row 6-column component is expressed by the following equation: (16) (17).

When a specific numerical value is assigned to the equation (16), if the equation (16) does not become 0, the rank of this matrix is 6, and the impedance z can be determined. Therefore, focusing on γ in equation (16), when I ⁱⁱ _n and I ⁱⁱⁱ _n do not include the zero phase component, the relationship of the following equation (18) is established. Similarly, when I ⁱ _n does not include the zero-phase component, γ is 0 as shown in the following equation (19). _{^{Therefore, I i n, I ii n}} , is either I ⁱⁱⁱ _n, we are necessary to include a zero-phase component.

When such voltage and current data is obtained, the impedance z can be determined by calculating the following equation (20) by the line constant calculation means 113, and the impedance matrix Z is obtained.

As described above, in the line constant calculating means 113 of the first embodiment, line constant Y, require data at three different power flow state to determine Z, matrix V _y, at least one 1 I _n both are It is necessary to include the zero phase component. Then, when the matrix ^{_{[V i y V ii y]}} T and where ^{_{[I i n I ii n I}} iii n] rank of ^T is 6 data has been obtained, the equation by the pseudo-inverse matrix (13) (14) Thus, the admittance y and impedance z can be determined, and the admittance matrix Y and impedance matrix Z, which are line constants, are obtained by the line constant calculation means 113.

(effect)
According to the present embodiment, the settling calculation related to the transmission line, which was necessary in the conventional protection control measurement device, can be greatly saved, and the correct line constant can be adapted to the environmental change around the transmission line in operation. Since it is possible to calculate and correct the settling value, it is possible to provide an economical and reliable protection control measuring device.

The second embodiment is a modification of the first embodiment. By defining a matrix shown in the following equation (21) based on the equation (3), the line constant calculating unit 113 uses the following equation (22). ) To obtain an admittance matrix Y.

Similarly, by defining the matrix shown in the following formula (23) from the formula (4), the line constant calculation means 113 obtains the impedance matrix Z by the following formula (24).

In the second embodiment, the matrices Y and Z can be solved without being decomposed into elements. That is, the original circuit equation is as shown in the above formulas (3) to (5) as follows.

At this time, Y and Z are 3 × 3 type matrices, and all other terms are 3 × 1 type matrices (vectors). Thus, by preparing three measurement values, i and v become 3 × 3 matrixes, and the simultaneous equations (3) and (4) become the following matrix equations (25) and (26).

From this, it is possible to obtain Y, and Z by taking the inverse of V _y and I _n. Even in the second embodiment, a zero-phase component is necessary. That is, in order to solve the matrix equation has to V _y and I _n are nonsingular. Further, since Z is regular, that I _n is regular are equivalent and that V _z is regular. Therefore, the matrix that collects the voltage data at both ends needs to be regular.

  The regularity of a square matrix is equivalent to the rank of the matrix being equal to its size, but if there is no zero-phase component in the collected data, there are only two valid data. Meaning that the rank of the matrix drops by one. Therefore, also in the second embodiment, it is indispensable that the zero phase component is included as in the first embodiment.

  As described above, also in the second embodiment, the admittance matrix Y is calculated by the line constant calculation unit 113 based on the electric quantity acquired from the electric quantity acquisition unit 111 in a state where the zero phase component is detected by the zero phase detection unit 114. And the impedance matrix Z can be obtained.

In the third embodiment, the line constant calculation unit 113 calculates the line constant by considering the power transmission line as a distributed constant circuit. In the second embodiment, when the power transmission line is a distributed constant circuit, the relationship between the input end and the output end is expressed by a four-terminal expression of the following equation (27). In the formula (27), Y and Z are admittance and impedance per unit length, and have the same form as the formula (1) described in the first embodiment because of reciprocity.

Here, each symbol in the formula (27) is as shown in the following formulas (28) to (30).

From the above equation (27), the following nonlinear simultaneous equation (31) relating to admittance and impedances Y and Z is derived.

  This nonlinear simultaneous equation (31) can be obtained Y and Z by solving with the Gauss-Newton method using measurement data in two states. This procedure is performed by the line constant calculation means 113. Specifically, by assuming the reciprocity of the line, this simultaneous equation (31) has the meaning of six complex expressions, the number of variables (the number of unknowns) is Y is a real number, Z Has 12 real numbers. On the other hand, since the equations obtained by one measurement are 6 complex numbers (12 real numbers), the line constants Y and Z can be theoretically estimated from two data unlike the case of the π-type equivalent circuit.

  It should be noted that the zero phase component is not indispensable in theory for the method of considering this transmission line as a distributed constant circuit, but it is desirable to include a zero component. In other words, the π-type equivalent circuit is an approximation in which a series of distributed constant lines is expanded and high-order terms are ignored. As a result, high-order terms that are theoretically effective are practically small, so they are almost ignored, and as a result, a solution search is performed with a π-type equivalent circuit. For this reason, some components are easily ignored, and as a result, they do not converge to a solution. Therefore, in order to arrive at a solution without relying on a high-order term even when searching for a solution of a distributed constant line, it is necessary to increase effective data by another method, and it is preferable to use the zero phase component as the method.

  As described above, also in the third embodiment, in a state where the zero phase component is detected by the zero phase component detecting unit 114, the admittance matrix Y and the line constant calculating unit 113 based on the amount of electricity captured from the electrical amount capturing unit 111. The impedance matrix Z can be obtained. As a result, the settling calculation related to the transmission line, which is necessary in the conventional protection control measurement device, can be greatly saved.

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

  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 protective relay that detected the accident, or the system operation. It is detected that it is a period. Specifically, the 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, so that the inside of the transmission line is detected. It is possible to detect that an accident has occurred.

(Function)
FIG. 5 shows a time chart of current and voltage accident waveforms. 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.

  FIG. 6 shows an operation flowchart of the fourth embodiment. Each step in FIG. 6 will be described in comparison with the amount of electricity at each time shown in FIG. Step S1 in FIG. 6 corresponds to the intake of electricity at 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 fourth embodiment having such a configuration, since the amount of electricity including the zero phase can be used by taking in the amount of electricity during an accident inside the transmission line or during restoration, the calculation accuracy of the line constant calculation unit 113 is high. It can be expected to improve. 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. To do. 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.

(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)
Example 6 shown in FIG. 9 shows a configuration in the case where the protection control measuring device 110 of the present invention 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 locating function 117. In step Sn + 2, the failure point evaluation unit 117 uses the output of the line constant calculation unit 113 to evaluate the failure point. Correct or reset the settling value.

(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. There was a gender issue. On the other hand, according to this embodiment, it is not necessary to calculate the line constant before starting operation, and the line constant can be calculated while adaptively reflecting the surrounding environmental changes during operation. 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 above-described line constant calculation means 113 is placed in this central processing unit, but the effect is equivalent to the above-described example.

(Constitution)
FIG. 11 shows a configuration when the protection control measuring device 110 is a distance relay that protects a power 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 calculating 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 calculating unit 113 to set the line constant of the distance relay 118. Correct or reset the settling value involved.

(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 if the setting is performed in advance by the conventional method, the line constant is obtained from the actual power flow after the operation and the re-setting 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. 13 shows a configuration in which the protection control measurement device 110 of the present invention is a current differential relay device that protects a transmission line. That is, a known current differential relay 119 is incorporated in the protection control measuring device 110 of the present invention, and the line constant obtained by the line constant calculating unit 113 for the current differential relay 119 is converted by the electric quantity capturing unit 111. It is input together with the amount of electricity acquired at each time point.

(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 perform current differential. The settling value related to the line constant of the relay 119 is corrected 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 102: Current transformer 103: Instrument transformer 104: Communication line 110: Protection control measuring device 111: Electric quantity taking means 112: Time synchronization means 113: Line constant calculating means 114: Zero Phase detection means 115: Transmission line accident state detection means 116: Line constant verification means 117: Fault location means 118: Distance relay 119: Charging current compensation relay

Claims (11)

Electric quantity capturing means that is installed at both ends of the line to be measured and captures the electric quantity at both ends of the transmission line;
A time synchronization means for performing the electric quantity taking-in in the electric quantity taking-in means at the same time;
Line constant calculating means for calculating the constant of the line as the admittance and impedance matrix from the quantity of electricity taken in by the quantity of electricity taking means as the π-type equivalent circuit or distributed constant circuit,
Using the zero phase component detecting means for detecting that the zero phase component is contained in a certain value or more in the amount of electricity to be taken into the electricity amount capturing device,
The line constant calculation means is started on the condition that the zero phase component detected by the zero phase component detection means exceeds a certain value, and the electric quantity is taken in at least two different time points by the line constant calculation means. A line constant measuring method, comprising: calculating a constant of a transmission line based on an amount of electricity taken into the means and its zero phase component. 2. The line according to claim 1, wherein the line is a π-type equivalent circuit, the line constant is defined by impedance Z and admittance Y, and the line constant is calculated by the following equation using the following equation. Constant measurement method.

Or

The line constant measuring method according to claim 1, wherein the line is a distributed constant circuit, and the admittance Y and the impedance Z per unit length of the line are calculated by using the following equations in the line constant calculating means. .

Electric quantity capturing means that is installed at both ends of the line to be measured and captures the electric quantity at both ends of the transmission line;
A time synchronization means for performing the electric quantity taking-in in the electric quantity taking-in means at the same time;
Line constant calculating means for calculating the constant of the line as the admittance and impedance matrix from the quantity of electricity taken in by the quantity of electricity taking means as the π-type equivalent circuit or distributed constant circuit,
A zero-phase component detecting means for detecting that the zero-phase component is included in the electricity quantity to be taken into the electricity quantity capturing device;
The line constant calculation means is started on the condition that the zero phase component detected by the zero phase component detection means is equal to or greater than a certain value, and is taken into the electricity quantity taking means at at least two different time points. A protection control measuring device for calculating a constant of a transmission line based on an amount of electricity and its zero phase. 5. The line constant calculation unit according to claim 4, wherein the line constant calculation unit defines the line as a π-type equivalent circuit, defines the line constant as impedance Z and admittance Y, and calculates the line constant using the following formula. Protection control measuring device.

Or

5. The protection control measurement according to claim 4, wherein the line constant calculating means calculates the admittance Y and the impedance Z per unit length of the line by using the following expressions, with the line being a distributed constant circuit. apparatus.

  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. 7. The protection control measuring apparatus according to claim 4, wherein at least one of the points is a time when a line accident or a line is open.   The 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. Item 7. The protection control measurement device according to any one of Items 4 to 6.   5. The failure point evaluation means for correcting or resetting a set value related to the line constant in the failure 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. To 6. The protection control measuring device according to any one of claims 1 to 6.   7. A distance relay for correcting or resetting a settling value related to ranging performance according to a calculation result of the line constant calculating unit is provided on an output side of the line constant calculating unit. The protection control measuring device described in 1.   5. The transmission line current differential relay is provided on the output side of the line constant calculating means, which corrects or resets a set value related to a charging current compensation function based on a calculation result of the line constant calculating means. To 6. The protection control measuring device according to any one of claims 1 to 6.

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