JP2506161B2 - Power system fault location method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a failure point of an electric power system for searching an accident point and a cause when an accident occurs in an electric power system such as a transmission line or a substation. Regarding orientation method.

[Conventional technology]

Conventionally, when a failure occurs in a power system such as a transmission line, it is necessary to go on-site patrol in order to find a failure point, and a lot of labor and time have been spent. Therefore, a fault point locating device that automatically searches for a fault point has been developed. There are various types of this fault point locating device, and in recent years, an impedance method in which a device is installed only on one terminal of a power transmission line and a fault point is located from the voltage / current information is becoming mainstream.

[Problems to be Solved by the Invention]

However, in the above impedance type fault point locator, the fault point is located using only the voltage / current information of one terminal of the transmission line.
1 to 3km due to the influence of CT), load flow and multi-terminal system
It is said that there is an orientation error. In many cases, the cause of the failure is unknown in the power system.Even if the above equipment is used to locate the failure point and perform a site inspection based on the result, the failure will be recovered naturally because the failure cannot be identified, and preventive measures should be taken to prevent recurrence. There are cases that cannot be taken.

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

[Means for solving the problem]

The fault point locating method of the power system according to the present invention for achieving the above-mentioned object, when an accident occurs in the power system, the time series data of the voltage / current of each terminal is set by the terminal installed at each important point of the power system. Simulate an accident in the fault location method that calculates the fault points and fault resistances of the power system by performing arithmetic processing using the time series voltage and current data collected and collected from each terminal in the central unit. Therefore, an equivalent circuit is set by connecting the fault point resistances of each line to the ground, and the fault point position and the fault point resistance for each data sampling are used as variables, and the fault points are determined using Kirchhoff's first and second laws. The formula of the voltage drop between the voltage and current measurement points is derived for each line of the transmission line and for each data sampling, and a constraint condition matrix in which a variable representing the measurement error is added to all of these formulas is formed. Set the objective function representing the sum of squares of errors, it is characterized in that for calculating the fault point resistance fault point by quadratic programming to minimize the objective function.

[Action]

In the fault point locating method of the power system according to the present invention, when a fault occurs in the power system, the load flow and the influence of the multi-terminal system are removed by using the voltage / current data of the multi-terminal for detecting the fault section, and the fault point is detected. The point resistance is located. or,
By using time-series voltage and current data during the time when the system state does not change after the occurrence of a failure, data redundancy is provided and a more accurate orientation is performed. further,
The cause of failure such as flashover due to electric shock and contact with trees is estimated from the numerical value of the resistance at the failure point and temporal changes.

〔Example〕

Hereinafter, a method for locating a fault point in a 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,
The case of the most basic two-terminal one-line transmission line is shown.
When a failure occurs in this power transmission line, the terminal 1 installed at the electric station at both ends of this power transmission line detects it and collects voltage / current data of each terminal of the power transmission line from PT / CT. And
In the central unit 2, the voltage / current data sent from each terminal 1 via the communication line are collectively processed to calculate a failure point and a failure point resistance.

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

In the central unit 2, the data from each terminal 1 is input by the input unit 2a.
Then, the quadratic programming (QP method) is used based on the voltage and current data of each terminal to calculate the fault position and fault resistance. The calculation of the above-mentioned fault point and fault point resistance is performed by the arithmetic processing unit.
It is done by 2b. In the output unit (printer, CRT, etc.) 2c connected to the arithmetic processing unit 2b, the date and time of failure as the arithmetic result,
It outputs the line name, failure phase, time change of failure point resistance, failure point position, etc.

Next, a specific example of the calculation method will be shown. First, the voltage of each terminal
Create a constraint matrix from current data. First
When a failure occurs in the power system shown in the figure, an equivalent circuit as shown in FIG. 2 can be considered. In Fig. 2, the transmission line impedance Zl is balanced for each phase, and the fault point impedances R _Fa and R
_Fb and R _Fc are only resistance, and if the switch SW is closed, a ground fault occurs, and if it is opened, a short circuit occurs. In case of ground fault, voltage of each terminal
Kirchhoff's first and second law equations using current data are as follows. _Sa = kl _Sa + R _Fa ( _Sa + _Ra ) _Sb = ll _Sb + R _Fb ( _Sb + _Rb ) _Sc = ml _Sc + _Fc ( _Sc + _Rc ) _Ra = (1-k) l _Ra + R _Fa ( _Ra + _Sa ) _Rb = (1-l) l _Rb + R _Fb ( _Rb + _Sb ) _Rc = (1-m) l _Rc + R _Fc ( _Rc + _Sc ) ... where _Sa , _Sb , _Sc , _Ra , _Rb , _Rc , _Sa ,
_Sb , _Sc , _Ra , _Rb , _Rc are measured values, k, l, m, _Fa ,
_{Fb, Fc} is variable, l is the known number, as it is for determined responded also by solving the equation, but that becomes larger orientation error due to the influence of error of PT · CT, each phase of the error ε ^+, ε ^- Distant Get the expression. _{Sa = kl Sa + R Fa (} Sa + Ra) + Sa + - Sa - Sb = ll Sb + R Fb (Sb + Rb) + Sb + - Sb - Sc = ml Sc + Fc (Sc + Rc) + Sc + - Sc _{^{- Ra = (1-k)}} l Ra + R Fa (Ra + Sa) + Ra +
^{_{- Ra - Rb = (1-}} l) l Rb + R Fb (Rb + Sb) + Rb +
^{_{- Rb - Rc = (1-}} m) l Rc + R Fc (Rc + Sc) + Rc +
- _Rc ^- Although ...... formula is formulated only one time section, create a formula from data of multiplanar data, for example, conveniently 24 cross-section of two cycles 30 ° sampling period can be regarded as the system condition does not change This is a constraint condition. The constraint matrix is shown in FIG.

On the other hand, the objective function I is the sum of squared error And Here, n means each time section.

When solving by the QP method, the value of the variable that minimizes the objective function under the constraint condition of FIG. 3 is obtained. This most likely non-negative variables by epsilon ^+, epsilon ^- combinations and k is the ratio the transmission line total length, l, m is Motomari, while locating the fault point accurately, fault point resistance R _Fa, R _Fb , R _{Fc is} also required.

Although the above calculation method exemplifies the case of a ground fault, a constraint condition matrix can be created from measured data and a fault position and a fault point resistance can be obtained by the QP method in the same manner when a short circuit occurs. As a result, the temporal transition of the resistance at the failure point can be grasped and the cause of the failure can be estimated.

The above-mentioned embodiment is a case of a simple model system, but this method is to increase the input information by installing terminals at every necessary place for multi-terminals, two-line transmission lines, and substation premises accidents. Applicable.

[Effects of the Invention] The fault point locating method of the present invention performs batch calculation using time series data of multiple terminals, can reduce the locating error, and can transmit two lines and six lines that are common in Japan. High-accuracy location is possible even for polyphase accidents involving two circuits on electric wires. This makes it possible to efficiently perform site inspections in the event of an accident and save labor.

In addition, there is a remarkable effect that it is possible to measure the failure point resistance at the time of failure that could not be captured conventionally and its change over time.Based on this information, the cause of the failure can be grasped, and equipment reinforcement measures can be taken for weak areas. Can be done accurately.

[Brief description of drawings]

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

Claims (1)

(57) [Claims] 1. When a power system accident occurs, terminal (1) installed at each key point of the power system collects time-series data of voltage and current at each terminal, and each terminal (1) central device. In the failure point locating method of calculating the failure point and the failure point resistance of the power system by performing the arithmetic processing using the time-series voltage / current data collected in (2), the failure of each line of the transmission line to simulate the accident. An equivalent circuit is established by connecting point resistances to the ground, and the failure point position and the failure point resistance for each data sampling are used as variables. Using Kirchhoff's first and second laws, The formula of the voltage drop between the transmission lines is derived for each line and each data sampling, and a constraint condition matrix in which a variable representing the measurement error is added to all the formulas is formed, and the objective function representing the sum of squares of those errors is formed. Set Fault point locating method of a power system and calculates the fault point resistance fault point by quadratic programming to minimize the objective function