JPH0776778B2 - Fault location method - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

In order to secure the reliability of power supply, the present invention speeds up failure recovery by locating a failure point that has occurred in a transmission line based on the voltage value and current value at the time of an accident measured at both terminals of the transmission line. The present invention relates to a fault location method.

[Prior art]

As shown in FIG. 2, when a failure occurs in the system where the electric stations A and B are at both terminals of the transmission line, it is necessary to know the distance from the A or B terminal to the failure point F or the position of the failure point F. It is necessary and indispensable for subsequent repair work of defective parts. Therefore, in the conventional fault point locating method, terminal devices A1 and B1 are provided at terminals A and B, and the voltage value and current value measured by this terminal device are A / D converted and then transmitted to the central device C, In the central unit C, a fault point is located by vector operation according to a predetermined orientation formula using the phase difference between the data from each terminal. Such a conventional fault location method will be described with reference to a system potential diagram at the time of a fault shown in FIG. The voltage values measured at the terminal devices A1 and B1 at the time of transmission line failure are _A and _B , the failure current amounts are _A and _B , the voltage value at the failure point F is _F , the distance between the A terminal and the B terminal is L, and the A terminal is To the fault point F is αL (where 0 <α <1), the distance from the B terminal to the fault point F is (1-α) L, and the unit length of the transmission line impedance is To do. _{A -αL A = F = B -} (1-α) L B ...
(1) By solving for αL from this equation (1), the distance to the fault point F can be obtained by the following equation. Where α
L _A and (1-α) L _B are voltage drops.

[Problems to be Solved by the Invention]

However, since the right side of the equation (2) is a vector operation, simultaneity between each terminal data is required. When the synchronous sampling method is used to achieve simultaneity between data, a synchronous signal transmission / reception circuit is required, and in the asynchronous sampling method, a phase difference correction circuit for sampling data by instantaneous failure detection is required. However, there is a drawback that the cost increases and the cost increases. The present invention does not require a special device for synchronizing the phase between the terminals when performing the vector operation processing of the fault location using the data from each terminal, and the current of the data collected at one location is not required. To provide a fault point locating method that reduces the cost and size of the device by eliminating auxiliary devices such as a synchronous signal transmitting / receiving circuit by performing the locating in synchronization with the calculation processing using the value. With the goal.

[Means for Solving the Problems]

According to the present invention, terminal devices are installed at both terminals of a power transmission line, voltage values and current values are asynchronously sampled at each terminal and stored in a memory, and a fault point locating operation is performed using the voltage values and current values. , The current value of both terminals sampled before the failure occurs, or the phase difference ΔΘ of the current values of both terminals from the current value of the sound phase of both terminals sampled after the failure occurs.
_AB is obtained, and the voltage value and current value of one terminal are _A and _A , the voltage value and current value of the other terminal are _B and _B , the distance from one terminal to the failure point is αL, and the transmission line impedance of unit length When is, the voltage value _{B 1} and the current value of the other terminal
_B is corrected by the phase difference ΔΘ _AB , Is configured to obtain the distance αL.

[Work]

Since the phase difference between the voltage value and current value of the failure phase at the time of failure is the same as the phase difference of the current values of the asynchronously sampled phases before the failure occurrence or the sound phase after the failure occurrence, the measurable before failure occurrence Asynchronous sampling was performed on both terminals by calculating the phase difference between the current values of each phase or of the sound phase after the failure and using this phase difference to correct the voltage and current values of one terminal at the time of failure. Synchronize the voltage and current values.

Examples of the invention

FIG. 1 is a diagram for explaining the state in the one-line operation two-terminal system, where (a) shows the state before the occurrence of the failure F and (b) shows the state after the occurrence of the failure F. As shown in FIG. 1 (a), the currents flowing in the phases a, b, and c of the A terminal and the B terminal are respectively I _a ^A , I _b ^A , I
The relations of these currents, _c ^A , I _a ^B , I _b ^B , and I _c ^B , are as follows before the failure occurs. Here, each electric quantity is a vector value unless otherwise specified. Assuming that the deviation of the synchronization of the current measured at the A terminal and the B terminal is Δθ _AB , the current value of each phase between the two terminals that is vectorally equal if the synchronization is achieved as shown in equation (3) is actually Since there is no synchronization in, the relationship between magnitude and phase is shown as follows. However, in equation (4), θ _a ^A , θ _b ^A , θ _c ^A , θ _a ^B , θ _b ^B , θ _c
^B is the phase of each current I _a ^A , I _b ^A , I _c ^A , I _a ^B , I _b ^B , I _c ^B. Here, the phase relationship of the equation (4) is expressed by using the above-mentioned synchronization shift Δθ _AB, which is as follows. If current values are actually collected at the A and B terminals before a failure occurs, the magnitudes of the current values are equal as shown in equation (4). Therefore, the phase difference ΔΘ between the current values collected at the A and B terminals is ΔΘ.
You can ask for _AB . Unless the sampling cycle at the A terminal and the B terminal is changed (however, the A terminal and the B terminal are not synchronized), the current value collected at the time of failure also has the same phase difference ΔΘ _AB . Therefore, at the time of a failure, for example, the phase difference ΔΘ obtained by calculating the phase of the current value and the voltage value measured at the B terminal from the current value before the failure occurred.
_The current value measured at the A terminal and the B terminal by correcting _B and determining _B ε ^jΔΘ _AB and _B ε ^jΔΘ _AB ,
The voltage values can be synchronized. Using the synchronized current value and voltage value, the arithmetic expression shown in Expression (2) is actually shown as follows. In the above description, since the magnitude of the current value of the failure phase is different between the A terminal and the B terminal at the time of failure and the phase difference cannot be obtained, the current values of the A terminal and B terminal before the failure are used. To obtain the phase difference ΔΘ _AB . However, considering after the occurrence of the fault F as shown in FIG. 1B, if the sound phase at the time of the fault, that is, as shown in FIG. Focusing on the b-phase or the c-phase, the following relationships are similarly established. Therefore, the phase difference Δ
By obtaining θ _AB , the current and voltage values measured at the A terminal and the B terminal can be synchronized.

【The invention's effect】

According to the present invention, when a failure occurs, the phase difference is obtained from the current value of each terminal before the failure or the current value of the sound phase of each terminal after the failure, and the phase difference is used for correction to perform synchronization. Therefore, hardware such as a phase difference correction circuit can be eliminated.

[Brief description of drawings]

FIG. 1 is an explanatory view of a state in a one-line operation two-terminal system, the second
The figure shows the configuration of a one-line operation two-terminal system, and Fig. 3 shows the system potential diagram at the time of failure. A, B: Terminal device, C: Central device.

Claims (1)

[Claims] 1. A terminal device is installed at both terminals of a power transmission line, and a voltage value and a current value are asynchronously sampled at each terminal and stored in a memory, and a fault point locating operation is performed using the voltage value and the current value. In this case, the phase difference ΔΘ _AB between the current values of both terminals is calculated from the current value of both terminals sampled before the failure or the current value of the sound phase of both terminals sampled after the failure, and the voltage of one terminal is calculated. If the values and current values are _A and _A , the voltage value and current value of the other terminal are B and B, the distance from one terminal to the fault point is αL, and the transmission line impedance of the unit length is Correct the voltage value _{B 1} and the current value _B with the phase difference Δθ _AB , A method for locating a failure point, characterized in that the distance αL is obtained in.