JPH0274877A - Method for spotting fault point in electric power system - Google Patents

Abstract

PURPOSE:To decrease the spotting errors of fault points by collecting the time series data of the voltage and the current of each terminal of a terminal device which is provided at every important point in an electric power system, sending the data to a central apparatus, and processing the data all together. CONSTITUTION:Terminal devices 1 are provided at the end of an electric power system. (The Figure shows a case wherein two terminals are provided in one circuit.) The terminal device 1 detects a fault and collects the current and the voltage in time series from a CT and a PT which are provided in each phase. The values are converted into digital quantities and stored in a memory. At the same time, the data are sent into a central apparatus 2 through a communication line L. The digital data are received with a receiving part 2a in the central apparatus. The data are operated and processed all together in an operating and processing part 2b so that the measuring errors become the minimum values. The result is printed out at an output part 2c. In this way, the kind of the fault is estimated based on the fault point is decreased. Thus the field inspection tour is made efficient.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is a method for detecting fault points in power systems to search for fault points and causes when faults occur in power systems such as transmission lines and substations. Concerning orientation methods.

[Conventional technology]

Traditionally, when a failure occurs in a power system such as a power transmission line, it is necessary to go on site patrol to discover the point of failure, which requires a lot of effort and time. Therefore, failure point locating devices that automatically search for failure points have been developed.

There are a wide variety of types of failure point locating devices, and in recent years,
The impedance method, in which a device is installed only at one terminal of a power transmission line, and the fault point is located from the voltage and current information, is becoming mainstream.〇 [Problem to be solved by the invention] However, the fault point of the impedance method described above is becoming mainstream. Since the location equipment uses only the voltage and current information of one terminal of the power transmission line to locate the fault point, it
1 to 3 depending on the influence of CT), load flow, and multi-terminal system.
It is said that there is a orientation error of km. In addition, in many cases, the cause of power system failures is unknown, and even if the failure point is located using the above equipment and site patrols are conducted based on the results, the cause of the failure cannot be determined because the failure recovers naturally, and measures to prevent recurrence cannot be taken. There are cases where it is not possible.

Therefore, the present invention has been made based on the above-mentioned circumstances, and an object thereof is to provide a fault point locating method for an electric power system that further reduces the location error and estimates the cause of the fault by calculating the fault point resistance. do.

[Means to solve the problem]

To achieve the above object, the power system failure point locating method according to the present invention, when an accident occurs in the power system, collects time-series voltage and current data of each terminal using terminals installed at each important point in the power system. The time-series voltage and current data of multiple terminals collected from each terminal to the central device are collectively processed to minimize measurement errors, and the fault points and fault point resistances of the power system are calculated. It is characterized by this.

[For production]

In the power system fault location method according to the present invention, when a fault occurs in a power system, the influence of load flow and multi-terminal system is removed by using multi-terminal voltage and current data for detecting fault sections, and the fault point is located. The fault point resistance is located. In addition, by using time-series voltage and current data during a time period during which the system status does not change after a failure occurs, redundancy is provided to the data and more accurate location is achieved. Furthermore, from the numerical value and temporal change of the resistance at the failure point, flash shorting due to electric shock,
This is to estimate the cause of the failure, such as contact with a tree.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for locating a fault point in an electric power system according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a system configuration diagram for the method of the present invention, showing the most basic case of a two-terminal-line power transmission line. If a failure occurs in this power transmission line, it is detected by terminal devices 1 installed at electrical stations at both ends of the power transmission line, and voltage and current data at each terminal of the power transmission line is collected from the PT-CT. Then, the central device 2 collectively processes the voltage and current data sent from each terminal 1 via the communication line to calculate the failure point and failure point resistance.

Each terminal 1 detects the occurrence of an accident and collects voltage and current data from the PT-CT. This data is converted into a digital amount and stored in a memory, and is also transmitted to the central unit 2 via a communication line by a transmitter.

In the central device 2, data from each terminal 1 is input to an input section 2a.
, and performs arithmetic processing using quadratic programming (QP method) based on the voltage and current data of each terminal to determine the fault location and fault point resistance. The above calculation of the failure point and failure point resistance is performed by the calculation processing section 2b.

An output section (printer, CRT) connected to the arithmetic processing section 2b
etc.) In 2c, the failure date and time, line name, failure phase, temporal change in failure point resistance, failure point position, etc. are output as calculation results.

Next, a specific example of the calculation method will be shown. First, a constraint matrix is created from the voltage and current data of each terminal. If a failure occurs in the power system shown in FIG. 1, an equinodal circuit as shown in FIG. 2 can be considered. In Fig. 2, the transmission line impedance ZL is assumed to be balanced for each phase, and the fault points Ivida 7s RFa,
RFb and RFc are only resistance bones, and switch S
If v is closed, it will be a ground fault, and if it is opened, it will be a short circuit. In the case of a ground fault, Kirchhoff's first method using the voltage and current data of each terminal,
The formula for the second law is as follows.

zt IS, +RF-(isa+tR,)V
sb=I Zt I sb+RFb (I sb+ I
ab) Vsc=mZ11sc+RFC(Isc+IR
6) VR&= (to 1-) Zj Ia, +Rp, (
IR, +1Sa) VRb” (1-1) Zi I R
b+RFb (IRb+ l5b) VR-” (1-n
t) zt I Rc+RF. (tR6+rs-)...
・・・・・・・・・・・・・・・・■Here, Vsa,
Vsb, huh? , negative, 9, Q scale. .

tc, l, m, RFa, R1”b, RFc
is a variable and Zt is a known number, and the answer can be found by solving Equation 0 as is, but the orientation error will be large due to the influence of the PT-CT error, so let the errors of each phase be ε and ε and use Equation 0. get.

VRC= (1-m) Zj I Rc+RF. (IR
c+Isj+εRe−εRc・・・・・・・・・・・・
・・・・・・■■The formula is formulated for only one time cross-section, but it can also be calculated from data from multiple cross-sections during a period in which the system status can be considered unchanged, for example, from data from 24 cross-sections due to two periods of 30° sampling. Create equation 0 and use this as a constraint. Figure 3 shows the constraint matrix.

On the other hand, the objective function I is the sum of squared errors +
(:))2+ (etc.3 items)2+(envy b(mu)2+(
jRb item) 2 + (jealous. (mu) 2 + (jealous. Shinanai...
・・・・・・・・・・・・・・・■. Here, n means each time section.

When solving using the QP method, values of variables that minimize the objective function (■) under the constraints shown in Figure 3 are found. As a result, a ratio of 12 m to the total length of the power transmission line is determined, and the fault point can be located with high precision, and the fault point resistance RFa
, RFb, and RFc are also determined.

In addition, in the above calculation method, the case of a ground fault is exemplified, but
Similarly, when a short circuit occurs, a constraint matrix is created from the measured data, and the fault location and fault point resistance can be determined using the QP method. As a result, it is possible to grasp the temporal change in the resistance at the fault point, and the cause of the fault can be estimated.

The above example is for a simple model system, but this method can also be applied to multi-terminal, two-circuit transmission lines, and substation premises accidents by installing terminals at each necessary location and increasing input information. Applicable.

〔Effect of the invention〕

The fault point locating method of the present invention performs batch calculations using multi-terminal time series data, and can reduce location errors. This makes it possible to efficiently patrol the scene of an accident and save labor.

Additionally, it has the remarkable effect of being able to measure the resistance at the failure point and its changes over time, which could not be detected in the past.Based on this information, the cause of the failure can be ascertained and measures taken to strengthen weak points in the equipment. Can be done accurately.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a device used in the fault point locating method for a power system according to the present invention in the case of a two-terminal-line power transmission line, and Fig. 2 is an equivalent circuit at the time of a failure in the case of a two-terminal-line power transmission line. FIG. 3 is an example of a constraint matrix used in the method of the present invention. 1...Terminal, 2...Central device

Claims (1)

[Claims] 1. When an accident occurs in the power system, terminals (1) installed at important points in the power system collect time-series data on the voltage and current of each terminal, and each terminal (1) transmits the data to the central device (2). A fault point locating method for a power system, characterized in that the time-series voltage and current data collected in the above are collectively processed so as to minimize the measurement error, and the fault point and fault point resistance of the power system are calculated.