JP2002064926A - Protective relay for electrical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the range of application by increasing the locating accuracy of an accident position k. SOLUTION: This protective relay comprises a pre-computing means 11 and a normal computing means 13. The pre-computing means 11 computes a fixed matrix and stores the fixed matrix in a pre-data storage means 12 based on the facilities data of a system. The normal computing means 13 is capable of determining the accident position k within a section at sufficiently high speed with high accuracy with equations derived from Kirchhoff's first and second laws, using the fixed matrix stored by the pre-computing means 11 based on the operating data of the system collected through data sampling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection relay device for a power system which has high accuracy in locating an accident point and has an extremely wide application range.

[0002]

2. Description of the Related Art As a protection relay device for an electric power system, many digital relays obtained by digitizing conventional mechanical relays have been developed.

[0003] Conventional protection relay devices include a current differential type, a direction comparison type, a distance relay type, a line selection relay type, an overcurrent relay type, and a current differential bus protection depending on an applied system and application. And differential ratio types for transformer protection. The operating principle of these protection relay devices is based on only one of Kirchhoff's first law and second law.

[0004]

According to the prior art, since a large number of types of protection relay devices must be individually selected and used, the equipment cost increases, and maintenance and inspection work becomes complicated. In addition, since the operation principle is based on only Kirchhoff's first law or second law, there is a problem that the location accuracy of the accident point is low and malfunction due to the location error is inevitable.

Accordingly, an object of the present invention is to provide a highly accurate location of an accident point by specifying the position of the accident point by an equation derived from Kirchhoff's first and second laws in view of the problems of the prior art. Another object of the present invention is to provide a protection relay device for a power system having an extremely wide range of application.

[0006]

In order to achieve the above object, the present invention comprises a pre-calculating means for calculating and storing a fixed matrix based on system data of a system, and a constant calculating means which operates every data sampling. Means, and a trip signal output means for outputting a trip signal in accordance with a trip command from the constant calculation means, wherein the constant calculation means is stored by the pre-calculation means based on the operation data of the system collected by data sampling. The gist of the present invention is to specify the location of an accident point in a section using an equation using only the accident point position derived from Kirchhoff's first and second laws as a variable, using a fixed matrix.

The pre-calculating means calculates and stores an intermediate matrix for calculating the fault point current at the midpoint of the section, and the constant calculating means uses the intermediate matrix stored by the pre-calculating means to calculate the section. The fault point current at the intermediate point can be calculated and the fault line can be specified.

The precalculation means calculates and stores an intermediate matrix for repeated calculation for each of a plurality of accident point positions in the section, and the constant calculation means uses the intermediate matrix stored by the precalculation means. Alternatively, the position of the accident point may be specified by repeated calculation.

Further, an accident cause analysis means is provided, and the accident cause analysis means calculates a change with time of the resistance at the accident point based on accident data collected during the accident by the constant calculation means, and estimates the cause of the accident. can do.

[0010] It should be noted that the constant calculation means calculates the system frequency of 10
It may be activated every data sampling set at twice or more times the frequency.

[0011]

According to the configuration of the present invention, when the facility data including the impedance of the system is input, the pre-calculating means calculates and stores a fixed matrix which does not depend on the position of the accident point based on the input. Therefore, the constant calculation means can calculate and specify the position of the accident point in the section at a sufficiently high speed by using the fixed matrix stored in advance by the preliminary calculation means. This is because the constant calculation means does not need to execute a large matrix calculation that requires a great deal of calculation time. In addition, the constant calculation means improves the location accuracy of the accident point position and simplifies the calculation by adopting an equation using only the accident point position as a variable derived from Kirchhoff's first and second laws. Can be. It should be noted that the equation used by the calculation means can be derived through almost the same unified procedure for all systems and applications.

The constant calculating means calculates the fault point current at the middle point of the section using the intermediate matrix for calculating the fault point current at the middle point of the section stored by the pre-calculating means. Is compared with a threshold value (for example, 0.05 p.u.), the accident line in the accident section can be easily and quickly identified.
This is because it is known that the fault point current does not change significantly even if the fault point position changes.

[0013] The constant calculation means uses the intermediate matrix for repeated calculation for each of a plurality of fault point positions in the section stored by the pre-calculation means, so that the fault point position can be specified at high speed by the repeated calculation. . It is preferable that the pre-calculation means set, for example, each position dividing the section into ten equal parts as a plurality of accident point positions, and the constant calculation means sets the repeated calculation method, for example, the NR method (N
ewton-Raphson method) can be used.

If the accident cause analysis means is provided, the accident cause analysis means calculates the change with time of the accident point resistance during the accident based on the accident data collected and stored by the calculation means at all times after the accident occurs. And the magnitude of the accident point resistance,
The cause of the accident can be estimated and output from the change with time, and it can contribute effectively to appropriate accident recovery measures. At this time, it is preferable that the accident cause analysis means outputs the accident point position or the accident section and the accident point position in addition to the accident cause.

The constant calculation means operates at every data sampling with a frequency of 10 times or more of the system frequency to capture the fact of the occurrence of the accident at a sufficiently high speed and, if necessary, to detect the system disturbance during the continuation of the accident. Accident data shown can be collected and stored.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

The protection relay device 10 for a power system includes a pre-calculation means 11, a constant calculation means 13, a trip signal output means 14, and an accident cause analysis means 16 (FIG. 1).
However, the protection relay device 10 is used, for example, to protect the two-line transmission lines L1 and L2 that interconnect the power transmission end including the power supply G and the power reception end including the constant current load L (FIG. 2). .

In FIG. 2, the transmission end voltage v_s , Receiving terminal
Pressure v_r , Load current i_d And In addition, the accident point position k (
However, when 0 ≦ k ≦ 1), the transmission ends of the transmission lines L1 and L2
Current i_s1, I_s2, Receiving end current i_r1, I_r2The arrows in FIG.
Direction, the accident point resistance R₁, R_Two , The fault point current i_f1,
i_f2Is assumed. In addition, the transmission end voltage v_s , Sending end current i
_s1, I_s2Are the voltage transformer PT and the current transformer C, respectively.
The voltage v via T and CT _p = V_s , Current i_c1= I_s1, I
_c2= I_s2It has been measured as.

The impedance Z of the transmission lines L1 and L2
_ij (i = 1, 2, j = 1, 2) is input to the pre-calculating means 11 of the protection relay device 10 as facility data of the system. The output of the pre-calculation means 11 is connected to the constant calculation means 13 via the preliminary data storage means 12, and the constant calculation means 13 supplies the voltage v _p , the currents i _c1 and i _c2.
In addition, a load current _id is input. However, the load current i _d is via a telemetry device (not shown), for example, shall be updated input every minute.

One output of the constant calculation means 13 is input to the trip signal output means 14 as a trip command S1, and the output of the trip signal output means 14 outputs the trip signal S as the trip signal S to each of the power transmission lines L1, L2. It is led to a circuit breaker (not shown) at the end. Also, the constant calculation means 13
Is connected to an accident cause analysis means 16 via an accident data storage means 15, and an output of the accident cause analysis means 16 is connected to an output means 17 such as a printer device or a CRT display device.

The pre-calculating means 11 transmits the impedance Z _ij of the transmission lines L 1 and L 2 via a data input device (not shown).
Is operated according to the program flowchart of FIG. That is, first, the program is expressed by equation (12) in FIG. 8 and (16) in FIG. It is stored in the previous data storage means 12 (program step (1) in FIG. 3, hereinafter simply referred to as (1)). 6 to 12 illustrate the technical basis of a series of calculation contents executed by the pre-calculation unit 11, the constant calculation unit 13, and the accident cause analysis unit 16 by using mathematical expressions.

Subsequently, the program is executed for the transmission lines L1, L
2 is divided into ten equal parts, and the accident point positions k = 0.0, 0.1, 0.
2... 1.0, according to equations (38) and (39) in FIG. The data is stored in the preliminary data storage means 12 and the process ends (2). In addition, intermediate for repetition calculation Of the fault point current at the intermediate point of the above.

On the other hand, the constant calculation means 13 is started, for example, at every 30 ° of the system voltage waveform, that is, at every data sampling set at a high frequency of 10 times or more of the system frequency, and operates according to the program flowchart of FIG. That always calculating means 13, a voltage is sampled most recently v _p, the current i _c1, i _c2, using a load current i _d to perform a series of calculations.

First, the program uses the intermediate matrix for calculating the fault point current at the intermediate point of the section stored in the preliminary data storage means 12 as shown in FIG.
According to equations 9) and (30), the fault point currents _{if (1)} and _{if (2)} at the intermediate point between the transmission lines L1 and L2, that is, at the fault point position k = 0.5, are calculated for each line (FIG. 4 program step (1), hereinafter simply referred to as (1)).
Subsequently, the program specifies which of the transmission lines L1 and L2 is the fault line according to the equation (31) in FIG. 11 (2). The program consists of the transmission line L1,
If there is no accident on each line of L2 (3), the process is terminated and the operation waits until the next operation.

When the program detects an accident that has occurred on any one of the transmission lines L1 and L2, (4) and (4) in FIG.
According to the equations (0) to (43), for the detected accident line, variables _If and _Vf for repeated calculation by the NR method are used,
The partial derivatives I _ff and V _ff are calculated (4). When calculating the variables _If , _Vf , the partial derivatives _Iff , _Vff , the program uses a fixed matrix stored in the preliminary data storage means 12 and an intermediate matrix for iterative calculation. . The program then proceeds to (3) in FIG.
In accordance with equations (6) and (37), the accident point position k is specified by repeated calculation by the NR method (5).

In this way, the program of the constant calculation means 13 is a chart established based on Kirchhoff's first and second laws by applying a series of calculation procedures shown in FIGS. Equations (5) to (7) of 6, (1)
Equations ((27) in FIG. 10, (27),
(28), the accident point position k of the section is specified through repeated calculation by the NR method (item (2) in FIG. 11). If it is determined in the program step (3) that there are more than two accidents, the program steps (4) and (5) are repeated for each accident line, and the average value of the accident point position k in each accident line is calculated. Is specified as the accident point position k of the section (FIG. 11 (3)).
Section).

Subsequently, the program determines whether or not the specified fault point position k is within the section of the transmission lines L1 and L2 to be protected (6). I do. On the other hand, when the accident point position k is within the section (6), the program outputs a trip command S1 to the trip signal output means 14 (7), and the trip signal output means 14 transmits the signal including the accident line. The trip signal S is sent to the circuit breaker on the power transmission end side of the electric wires L1 and L2 to cause a trip.

Thereafter, the program is executed as shown in FIG.
By the formula, the program step (5 (8) and in the program step (4) Is stored in the accident data storage means 15. The program repeats this operation for each data sampling until the accident is shut off ((9),
(1), (2)... (9)), it is possible to collect operation data of the system during the accident continuation as accident data indicating system disturbance during the accident continuation, and store the data in the accident data storage unit 15.

When the accident is cut off (9), the program activates the accident cause analyzing means 16 (10) and ends. On the other hand, the accident cause analysis means 16
, It operates according to the program flowchart of FIG.

The program is always calculated by the calculating means 13.
Accident data storage means 1 during accident continuation Calculate (program step (1) in FIG. 5, hereinafter simply referred to as (1)) According to step (8), accident data is used for each data sampling during the accident. (T).

[0031] , The cause of the accident is analyzed and estimated (2). It can contribute to old measures.

[0032]

[Other embodiments]

It can be generally applied to any accident section (FIG. 13A). However, in FIG.
Equations (1) to (3) are established based on Kirchhoff's first and second laws, and equations (5) to (7) are general equations for the accident section.

Therefore, a general calculation procedure for an arbitrary accident section can be summarized as follows. 1. Equations (5) and (6) in FIG. 13B are set for each section (corresponding to equation (8) in FIG. 6). 2. When a plurality of sections are included, a section connection equation and a current continuation equation are set. 3. Add equations of PT and CT measurement values ((9) in FIG. 7)
Equation). (Corresponding to the equation (13) in the figure). Created (equivalent to equation (17) in FIG. 9). (Equivalent to equation (19)). 7. 6 above. The ratio of the real part to the imaginary part of the equation is taken, R is eliminated, and an equation of only k is made ((27), (2) in FIG. 10).
8) Equation). 8. 7 above. Is calculated from the following equation. At this time, a fixed matrix and an intermediate matrix are pre-calculated and stored in order to execute the repetitive calculation according to the NR method as needed and to speed up the repetitive calculation ((3 in FIG. 11).
Equations 2) to (37), equivalent to equations (38) to (43) in FIG. 9. 6 above. Is substituted for k to obtain R (corresponding to equations (44) and (45) in FIG. 12).

8. The above 8. Is repeated, for example, as shown in FIG.
Of the respective systems shown in (A) to (E), it is necessary only for FIG. Therefore, for each of the systems shown in FIGS. In this case, the accident point position k can be uniquely obtained from the equation, and in this case, the pre-calculation of the fixed matrix and the intermediate matrix is unnecessary. However, even in this case, in order to quickly determine and detect the fault line, it is preferable that only the intermediate matrix for calculating the fault point current at the middle point of the section is calculated in advance and stored.

[0035]Are the electromotive force, impedance, and transient of generator g, respectively.
It is a current. Also,, The current measured on the power receiving side. In addition,
In (E), the symbol R _t Is the tower leg resistance of the tower.

[0036] The measurement system for both ends is measured. Information on the type of system configuration as shown in FIG. 2 and FIGS. 14A to 14E is input together with the pre-calculation unit 11 as facility data of the system in FIG.
1. It is used to select a series of calculation procedures to be executed by the constant calculation means 13 and the accident cause analysis means 16.
Furthermore, the one-end measurement system is replaced with the power transmission side. The lip signal S is transmitted to the circuit breaker on the power receiving end side.

In the above description, the accident cause analysis means 16 in FIG. 1 may automatically output a circuit breaker closing signal for automatic reclosing to the outside based on the estimation result of the accident cause. However, the circuit breaker closing signal shall be sent to the circuit breaker by constructing an appropriate interlock based on other automatic reclosing conditions, in addition to the result of the estimation of the cause of the accident. It may be constructed either inside or outside the device 10.

The operation principle of the present invention can be applied to a fault locator device for locating an accident point k and an oscilloscope device for collecting accident data relating to system disturbance at the time of the accident. However, for these uses, it is not necessary to provide the trip command output function of the calculation means 13 (program step (7) in FIG. 4) and the trip signal output means 14, and the accident data storage means 15 for the latter use is required. The thing Is preferred.

According to the present invention, from the operating principle, the location accuracy of the accident point is extremely high, and it is easy to achieve the location accuracy of 2% and 0.2% for the one-end measurement system and the both-end measurement system, respectively. Can be. In addition, regardless of the system voltage hierarchy, the neutral point grounding method, whether cables and overhead lines are mixed or mixed, and the existence of multiple sections in multi-terminal transmission lines, almost the same calculation procedures are used for all systems and applications. Can be applied uniformly. Further, it is difficult to detect the occurrence of an accident by the conventional method, for example, a micro-ground fault of 700Ω or more in a 154 kV system, a single-ground fault of a resistance grounding system, a single-ground fault of a two-line transmission line, and the like. It is also possible to reliably detect and locate a special accident that has been done.

[0040]

As described above, according to the present invention, by providing the pre-calculation means and the constant calculation means, the constant calculation means can use the fixed matrix stored by the pre-calculation means to generate the Kirchhoff's signal. First law,
Since the location of the accident point can be specified sufficiently quickly by the equation derived from the second law, the location accuracy of the accident point is extremely high, and a uniform calculation procedure can be applied to all systems and applications. In addition, the application range is extremely wide, and there is an excellent effect that the facility inspection cost can be reduced and the maintenance and inspection work can be facilitated.

[Brief description of the drawings]

Fig. 1 Overall block system diagram

FIG. 2 is an explanatory diagram of an applicable system.

FIG. 3 is a program flowchart (1).

FIG. 4 is a program flowchart (2).

FIG. 5 is a program flowchart (3).

FIG. 6 is an explanatory diagram of a calculation procedure (1).

FIG. 7 is an explanatory diagram of a calculation procedure (2).

FIG. 8 is an explanatory diagram of a calculation procedure (3).

FIG. 9 is a diagram illustrating a calculation procedure (4).

FIG. 10 is an explanatory diagram of a calculation procedure (5).

FIG. 11 is an explanatory diagram of a calculation procedure (6).

FIG. 12 is an explanatory diagram of a calculation procedure (7).

FIG. 13 is a diagram illustrating a calculation procedure according to another embodiment.

FIG. 14 is an explanatory view corresponding to FIG. 2, showing another embodiment.

[Explanation of symbols]

k: Accident point position S1 Trip command S Trip signal 10 Protection relay device 11 Precalculation means 13 Constant calculation means 14 Trip signal output means 16 Accident cause analysis means

Claims (5)

[Claims] 1. A pre-calculating means for calculating and storing a fixed matrix based on system data of a system, a constant calculating means which operates every data sampling, and outputting a trip signal in response to a trip command from the constant calculating means. Trip signal output means, wherein the constant calculation means uses Kirchhoff's first law based on operation data of the system collected by data sampling, using a fixed matrix stored by the pre-calculation means. ,
A protection relay device for an electric power system, characterized in that an accident point position of a section is specified by an equation using only an accident point position derived from the second law as a variable. 2. The pre-calculation means calculates and stores an intermediate matrix for calculating a fault current at an intermediate point of a section, and the constant calculation means calculates an intermediate matrix stored by the pre-calculation means. 2. The protection relay device for a power system according to claim 1, wherein the fault point current is calculated at an intermediate point of the section to identify the fault line. 3. The pre-calculation means calculates and stores an intermediate matrix for iterative calculation for each of a plurality of accident point positions in a section, and the constant calculation means calculates an intermediate matrix stored by the pre-calculation means. The accident point position is identified by iterative calculation using a matrix.
A protection relay device for a power system according to claim 2. 4. An accident cause analysis means is provided, and the accident cause analysis means calculates a time-dependent change in the resistance of the accident point based on the accident data collected during the continuation of the accident by the constant calculation means. 2. The method according to claim 1, wherein
A protection relay device for an electric power system according to claim 3. 5. The system according to claim 1, wherein said constant calculation means includes a system frequency of 10%.
The protection relay device for a power system according to any one of claims 1 to 4, wherein the protection relay device is activated every time data sampling is performed at a frequency twice or more.