JP2006054965A - Accident determining device for transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately locate an accident near a terminal of parallel two-line section, by creating fixed matrices with an assumed accident point current at the start point or the terminal of each branch. <P>SOLUTION: This device comprises an on-accident pre-calculating means 11 that creates and stores the fixed matrices D<SB>VF</SB>, D<SB>VF</SB>for calculating an accident point voltage and the accident point current assumed at the start point or the terminal of each branch on the basis of facilities data of a system, a normally monitoring means 13 that operates for each data sampling to renew and store a voltage V<SB>PT</SB>and a current I<SB>CT</SB>of an measurement end by sampling, and an on-accident calculating means 14 that is started by the monitoring means 13 on the occurrence of the accident. This calculating means 14 calculates accident position reactance across each end using the fixed matrices stored by the pre-calculating means 11, and the sampling data collected by the monitoring means 13 to locate an accident branch and an accident position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an accident specifying device for a power transmission system that can be suitably applied to a power transmission system having parallel two-line sections (two-line combined sections).

  There is known a matrix type accident identification device capable of accurately locating an accident point position on a transmission line (Patent Document 1).

This is a technology that establishes a basic equation for two parallel extra high voltage transmission lines by applying the first and second laws of Kirchhoff and determines the location of the accident point at high speed by matrix calculation. In addition to the fault locator device for locating the point position, the oscilloscope device for collecting accident data related to system disturbance at the time of the accident, etc., it is also sufficient as a protective relay device in combination with the relay for operating the circuit breaker to remove the accident section It has practical accuracy and responsiveness.
JP 2002-64926 A

  According to such a conventional technique, the accident point position (hereinafter also referred to as the accident point) is specified assuming an accident in the middle of the section, and therefore, a variable k (0 ≦ k) indicating the accident point position in the basic equation. ≦ 1) entered, and there was a problem that the accident localization error near the end of the parallel two-line section tends to be large.

  Therefore, the object of the present invention is to simplify the basic equation by creating a fixed matrix by assuming the fault current at the start or end of each branch, and to accurately prevent an accident near the end of a parallel two-line section. An object of the present invention is to provide an accident identification device for a power transmission system that can be standardized.

  In order to achieve this object, the configuration of the present invention creates and stores a fixed matrix for calculating the fault point voltage and fault point current at the time of an accident at the start or end of each branch based on the facility data of the system. Comprising pre-calculation means, constant monitoring means that operates every time data sampling, samples and updates the voltage and current at the measurement end, and accident calculation means that is activated by the constant monitoring means when an accident occurs, The pre-calculation means creates a fixed matrix assuming the fault point current at the beginning or end of each branch, and the accident calculation means includes the fixed matrix stored by the pre-calculation means and the accidents collected by the constant monitoring means. The accident point reactance at both ends of each branch is calculated using the sampling data of the hour, and the accident branch and accident point are calculated. As its gist to identify.

  Note that the pre-calculation means can create a fixed matrix assuming a virtual phase shifter at the terminal bus of the parallel two-line section.

  In addition, the accident time calculation means can calculate the accident point reactance at both ends of each branch by using the load before the accident and the generator output at the non-measurement end, and the accident point reactances at both ends have different signs. Can be identified as an accident branch, and a point where the accident point reactance is zero in the accident branch can be identified as an accident point.

  However, in the present invention, “node” means a connection point or branch point of a transmission line, “section” means from node to node of the transmission line, and “branch” means each line in each section. It shall be said.

  According to the configuration of the present invention, the pre-calculation means hypothesizes an accident at the start or end of each branch and calculates a fixed matrix for each start and end of each branch for each section based on the system facility data. Therefore, the variable k indicating the accident point (0 ≦ k ≦ 1) is not included in the basic formula, the basic formula itself can be simplified, and the matrix calculation can be simplified. On the other hand, assuming the fault point current at both ends of each branch is not only assuming the fault point impedance at both ends of each branch, but the reactance of the fault point impedance, that is, the fault point reactance is zero at the fault point. Thus, different signs are used at both ends of the accident branch, and it can be used directly for accident branch detection determination and accident point identification.

  Note that the data sampling of the constant monitoring means is preferably set at a high frequency of 10 times or more of the system frequency, for example. In addition, the accident time calculation means should use data after a time of more than 90 degrees of phase angle from the occurrence of the accident as sampling data at the time of the accident in order to reduce the direct current component of the accident current immediately after the accident. Is preferred. Therefore, the constant monitoring means updates and stores sampling data for one past cycle, for example.

  The constant monitoring means reads the measured values of the voltage transformer and the current transformer provided at the measurement end of the system as sampling data as the voltage and current at the measurement end. In addition, the accident calculation means pays attention to the sign of the accident point reactance at both ends of each branch, and can specify a branch having an accident sign reactance at both ends of each branch as an accident branch. , The point at which the accident point reactance becomes zero can be obtained by proportional distribution with respect to the length of the section, and can be specified as the accident point. In general, the reactance of the fault point impedance, that is, the fault point reactance is negligible compared to the fault point resistance. As the deviation from the actual fault point, the positive or negative direction corresponds to the reactance of the transmission line impedance. It is because it is known that it shifts to.

  The pre-calculation means can simulate an accident in which the fault current flows unbalanced in each line by assuming a virtual phase shifter on the bus at the end of the parallel branch of each section. Accident localization accuracy near the end of the can be improved.

  The accident time calculation means can increase the calculation accuracy of the accident point reactance at both ends of each branch and improve the accident localization accuracy by using the load before the accident and the generator output at the non-measurement end together. Note that the load at the non-measurement end and the generator output are collected, for example, via a telemeter, and data before n cycles (n = 1, 2,...) Of the system frequency from the occurrence of the accident is used. However, the integer n is preferably set to n = 1 in order to eliminate the influence of the system frequency fluctuation. The load is assumed to have a constant current characteristic, and the load current is constant before and after the accident, and the generator extracts the fixed portion of the generator current that is calculated by assuming that the internal induced voltage is unchanged before and after the accident. It shall be used to calculate the accident point reactance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The accident identification device 10 for a power transmission system includes a prior calculation means 11, a constant monitoring means 13, and an accident time calculation means 14 (FIG. 1). However, the accident identification device 10 is used as a fault locator device, an oscilloscope device, or a protection relay device for a power transmission system having two parallel circuit sections.

  The pre-calculation means 11 is input with facility data of a power transmission system to be protected via a data input device (not shown). Further, the output of the preliminary calculation means 11 is connected to the storage means 12, and the output of the storage means 12 is connected to the accident time calculation means 14.

The outputs of the constant monitoring means 13 are individually connected to the storage means 12 and the accident time calculation means 14. The output of the accident calculation means 14 is connected to an output means 15 including, for example, a printer device, a display device, an output relay for trip signals St1, St2, and the like. In addition to the voltage transformer PT and the current transformer CT provided at the measurement end of the power transmission system, the measurement values of the telemeter TM are input to the constant monitoring means 13 (model system diagram of FIG. 5). However, the model diagram of FIG. 5, in addition to the breaker CB in the system, the load W _L of the non-measurement ends, is shown in telemetry TM is combined to collect data of the generator output W _G. 5 to 15, the technical basis of a series of calculation contents executed by the preliminary calculation means 11, the constant monitoring means 13, and the accident time calculation means 14 is described in detail by mathematical formulas.

  The pre-calculation unit 11 operates according to the program flowchart of FIG. 2 when facility data of the power transmission system is input.

の各区間について、ブランチの始端、終端ごとに算出される。なお、事前計算手段１１は

れているように、並行２回線区間の各ブランチの終端の母線に仮想の移相器Ｖ_h(1)、Ｖ

記憶手段１２に出力して記憶させる（３）。 That is, when the program stores the input data of the equipment data (program step (1) in FIG. 2, hereinafter simply expressed as (1)), according to equations (3.13) and (3.14) in FIG.

Is calculated for each start and end of the branch. The pre-calculation means 11 is

As shown in the figure, virtual phase shifters V _{h (1)} , V _h

The data is output to the storage means 12 and stored (3).

  The constant monitoring means 13 is activated, for example, every 30 ° of the system voltage waveform, that is, every time data sampling is set at a frequency of 10 times or more of the system frequency, and operates according to the program flowchart of FIG.

The program starts with the measured values of the voltage transformer PT and the current transformer CT, that is, the voltage V _PT at the measurement end, the current I _CT , the load W _L at the non-measurement end collected via the telemeter TM, the generator enter the sampled data by reading an output W _G (program step (1 in FIG. 3), hereinafter simply referred to as (1)), and outputs their sampling data storage means 12 stores (2 ). Subsequently, the program determines whether or not an accident has occurred in the power transmission system (3), and when an accident has occurred, activates the accident time calculation means 14 and ends (4). If the accident does not occur (3), the process ends and waits for the next start-up. However, the storage unit 12, before the accident of the voltage V _PT, current I _CT, load W _L, as a memory area for the generator output W _G, and one cycle corresponds at least system frequency is prepared, therefore, The program operates cyclically for each data sampling, so that at least one past sampling data immediately before the accident can be sequentially updated and stored in the storage means 12.

In the program step (3) in FIG. 3, whether or not an accident has occurred can be determined based on a sudden change in the voltage V _PT and the current I _CT . For example, if there is a one-line ground fault, the ground voltage of the accident phase approaches zero, the ground voltage of the healthy phase jumps to nearly 3 ^1/2 times, and the zero-phase voltage corresponding to the vector sum of the voltage V _PT is Appear. Moreover, a large line-to-line short circuit current is generated in the case of a ground fault or short circuit accident involving two or more lines.

  When the accident time calculation means 14 is activated by the program step (4) of the constant monitoring means 13, it operates according to the program flowchart of FIG. However, the program steps (1) to (11) in FIG. 4 correspond to the accident time calculation means 14, and the program steps (12) to (17) correspond to the output means 15.

もに、計測端の電圧Ｖ_PT、電流Ｉ_CT、非計測端の負荷Ｗ_L 、発電機出力Ｗ_G を記憶手段１２から読み出して入力する（図４のプログラムステップ（１）、以下、単に（１）のように記す）。ただし、負荷Ｗ_L 、発電機出力Ｗ_G は、事故発生から系統周波数の１サイクル前のデータを記憶手段１２から読み出すものとする。また、電圧Ｖ_PT、電流Ｉ_CTは、事故発生からたとえば位相角９０°相当程度の時間経過後のデータを読み出すものとする。

Moni, the voltage V _PT measurement end, current I _CT, load W _L of the non-measurement end, entering the generator output W _G from the storage unit 12 (program step in FIG. 4 (1), hereinafter simply ( 1)). However, the load W _L, the generator output W _G shall read from accident one cycle before the data system frequency from the storage unit 12. Further, the voltage V _PT, current I _CT is the accident for example as to read the data after the passage of the phase angle 90 ° considerable time.

づいて、プログラムは、各ブランチの始端、終端について、図１３の(4.1)、(4.2)式によ

を算出し、さらに、図１２の(3.15)〜(3.17)式を適用して各ブランチの両端における事故

、プログラムは、図１３の（4.3）式により、事故線を判定することができる。 Thereafter, the program performs a Fourier transform on the voltage V _PT and the current I _CT as a vector value.

Therefore, the program uses the equations (4.1) and (4.2) in FIG. 13 for the start and end of each branch.

And then apply the equations (3.15) to (3.17) in Fig. 12 to apply accidents at both ends of each branch.

The program can determine the accident line according to the equation (4.3) in FIG.

After that, the program applies the equation (4.4) in FIG. 13 to identify the accident branch for each branch including the accident line (10), and applies the equation (4.5) in FIG. 13 to identify the accident point. (11). That is, the accident branch can detect and determine that the signs of the accident point reactances X _{f (NF)} and X _{f (NT)} at both ends of each branch are different, and the accident point is determined by the accident point reactance X _{f ( NF)} and _{Xf (NT)} can be specified by proportionally dividing by the length of the section. However, a plurality of candidates may be found for the accident branch identified in this way.

  After that, the program identifies the breaker CB suitable for accident blocking based on the identified accident branch number NB and the relative position k (0 ≦ k ≦ 1) of the accident point, and outputs trip signals St1, St2. At the same time ((14), (16), FIG. 14), the accident branch number NB and the relative position k of the accident point are output to the outside (17), and the process ends. However, the program step (12) in FIG. 4 expects an accident location error ε (%), and when an accident point is specified in the vicinity of the bus on the terminal side of the accident branch, the program step (12) automatically starts after tripping the counterpart circuit breaker CB. This is branch determination for realizing a series trip ((15), (16)) for tripping the end accident branch breaker CB. That is, trip signals St1 and St2 from program steps (14) and (16) in FIG. 4 indicate trip signals for direct trip and series trip, respectively.

  The simulation test results of the accident identification device 10 are shown in FIGS. In the simulation test, the 66 kV parallel two-line four-terminal power transmission system shown in FIG. 16A is assumed, and loads L1 to L3 having constant current characteristics are assumed for each electric power bus that uses both lines.

FIG. 16B shows the calculation result of the fault point reactance X _f at both ends of each branch by simulating a one-line ground fault at k = 0.95 of the branch B3 in the section S2 in FIG. Is. The accident point reactance _Xf exists for each branch because virtual phase shifters _{Vh (1)} and _{Vh (2)} are inserted in the electric power buses at the end of the parallel two-line section. . In addition, the accident point reactance _Xf decreases from the power source side toward the load side, and it can be determined that the branches B3 and B4 in the section S2 are accident branches. For example, by applying the equation (4.3) in FIG. A phase of B3 is an accident line, branch B3 is identified as an accident branch (NBsol = 3), and accident point reactances X _f = 0.156 and -0.005 at both ends of branch B3 are proportionally prorated, k The accident point is specified as = Ksol = 0.972. The accident orientation error Δk = 0.972−0.950 = 0.02, and a good accident orientation result was obtained.

  The test results are summarized in FIG. However, in FIG. 17, the comparative example is a simulation result by the conventional method of JP-A-2002-64926. In addition, cases 1 to 4 in FIG. 17 are all 1-line ground faults, and case 5 is a 4-line ground fault across two lines. Regarding the accident near the terminal of each branch, the average accident localization error of the comparative example is 10.2%, which is 2.3% in the example, which is a great improvement.

リアクタンスＸ_f を求めるので（図１２の(3.15)、(3.16)式）、論理が単純明解であり
、運用・保守担当者が理解しやすい。
ｂ．保護区間の境界点で事故点リアクタンスＸ_f を判定するため、事故区間（事故ブラン
チ）の特定精度が高く、多端子送電線の保護に適している。
ｃ．送電線の中性点接地方式に関係なく、また、非接地系の配電線にも適用できるので、
汎用性に富んでいる。 The technical features of the present invention are summarized as follows.

Since the reactance _Xf is obtained (expressions (3.15) and (3.16) in FIG. 12), the logic is simple and clear, and it is easy for the person in charge of operation and maintenance to understand.
b. Since the accident point reactance _Xf is determined at the boundary point of the protection section, it is highly accurate in identifying the accident section (accident branch) and is suitable for protecting multi-terminal transmission lines.
c. Regardless of the neutral point grounding method of the transmission line, it can also be applied to ungrounded distribution lines,
Rich in versatility.

Overall configuration block diagram Program flow chart (1) Program flow chart (2) Program flow chart (3) Calculation contents explanatory diagram (1) Calculation contents explanatory diagram (2) Calculation contents explanatory diagram (3) Calculation contents explanatory diagram (4) Calculation contents explanatory diagram (5) Calculation contents explanatory diagram (6) Calculation contents explanatory diagram (7) Calculation contents explanatory diagram (8) Calculation contents explanatory diagram (9) Calculation contents explanatory diagram (10) Calculation contents explanatory diagram (11) Simulation test explanatory diagram Simulation test results explanatory chart

Explanation of symbols

Ｘ_f …事故点リアクタンス
Ｖ_h(1)、Ｖ_h(2)…移相器
１１…事前計算手段
１３…常時監視手段
１４…事故時計算手段

特許出願人 辻 浩 一
代理人 弁理士 松 田 忠 秋
V _PT … Voltage I _CT … Current W _L … Load W _G … Generator output

X _f ... Accident point reactance V _{h (1)} , V _{h (2)} ... Phase shifter 11 ... Pre-calculation means 13 ... Constant monitoring means 14 ... Accident time calculation means

Patent applicant Koichi Tsuji
Attorney Tadaaki Matsuda, Attorney

Claims (5)

  Based on the facility data of the system, pre-calculation means to create and store a fixed matrix for calculating the accident point voltage and accident point current at the beginning or end of each branch, and to operate and measure each data sampling A constant monitoring means that samples and updates the voltage and current at the end, and an accident time calculation means that is activated by the constant monitoring means when an accident occurs, wherein the pre-calculation means includes A fixed matrix is prepared assuming an accident point current at the terminal, and the accident calculation means includes a fixed matrix stored by the pre-calculation means and sampling data at the time of the accident collected by the constant monitoring means. It is used to calculate the accident point reactance at both ends of each branch and identify the accident branch and the accident point. Accident specific device for the power transmission system.   2. The accident identification device for a power transmission system according to claim 1, wherein the pre-calculating means creates a fixed matrix assuming a virtual phase shifter at the bus at the end of the parallel two-line section.   3. The transmission system according to claim 1 or 2, wherein the accident time calculation means calculates the accident point reactance of each node by using the load before the accident at the non-measurement end and the generator output together. Accident identification device.   4. The accident identification device for a power transmission system according to claim 1, wherein the accident time calculation means identifies branches having different signs of accident point reactances at both ends as accident branches. 5. The accident identification device for a power transmission system according to claim 4, wherein the accident time calculation means identifies a point where the accident point reactance becomes zero in the accident branch as an accident point.

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