JPS626183A - Faulty point locating system - Google Patents

Abstract

PURPOSE:To locate a fault point with high accuracy by deciding a fault phase from each phase of three phases, and locating a fault direction, and a distance between a located point and the fault point, by a phase difference of a current and a voltage of the fault phase, and a ratio of an absolute value, respectively. CONSTITUTION:A current and a voltage of each phase of a transmission line are measured by a current detector 51 and a voltage detector 52, and its result is inputted to a phase difference detector 53. The phase difference detector 53 derives a phase difference of both of them, and a fault direction locating device 56 locates a fault direction, based on a value of the phase difference and inputs it to a recorder 60. On the other hand, an impedance meter 54 derives an impedance extending from a measuring point to a fault by an output ratio of the current detector 51 and the voltage detector 52, and also a fault range finder derives a fault distance from the impedance per unit length which has been given in advance, and inputs it to the recorder 60. In this regard, only when an output of the current detector 51 has exceeded a prescribed value, the fault point is located by a trigger generator 58.

Description

[Detailed description of the invention] [Subject of invention] The present invention relates to a method for locating fault points in a power system.

[Prior art] In recent years, electric power systems have become more complex as demand has expanded and the area has become wider, with longer cables, more cables, and more terminals. The development of a point location method is desired.

Currently used fault point locating methods include the pulse radar method, which applies an impulse at the time of a fault and measures the time it takes for the reflected wave to return to locate the fault point; Measured at electric stations at both ends,
There is a nerge reception method that locates the failure point based on the time difference, and all of these methods make use of the traveling wave phenomenon.

However, the applied pulse or fault surge has a fast propagation speed, and as it progresses, ・′
There is clearly a limit to performance improvement due to attenuation, distortion, reflection at suspension points and branch points, and confusion with lightning.

As a way to improve this problem, a method has been proposed in which the electric current flowing through the overhead ground wire of an overhead power transmission line is detected at multiple locations and the fault section is located from the phase information. This method has the drawback of high equipment costs because it requires a long information transmission path and a large number of devices.

[Object of the invention] The present invention improves the drawbacks of the prior art described above, and
The purpose of this invention is to provide a new method that can accurately locate failure points for both ground faults and short circuits in power systems with many system branches and multiple power sources.

[Summary of the invention] That is, the faulty phase is determined from each of the three phases, the current and voltage of the faulty phase are measured, and the direction of the fault is determined from the phase difference between the two, and at the same time, the absolute values of each of the current and voltage are determined. The configuration is such that the distance from the control point to the failure point is determined based on the ratio.

[Supplementary explanation of the invention] The principle of the present invention will be explained with reference to the drawings.

FIG. 3 is a model diagram of a single-line power transmission system having a power source and a load at both ends. Power supply (Eu.

Ev, Ew)2. Equivalent impedance of power supply and load 3
and a grounding resistor 4.

For example, if a ground fault occurs in the ■ phase at an arbitrary point F (hereinafter referred to as failure point F) on the power transmission line 1, the fault voltage Vu of the ■ phase will be maximum on the power supply side at both ends, as shown in Figure 4, and the failure will occur. It becomes zero at point F. On the other hand, the fault current Iu has opposite phases at both ends of the fault point F, and the current value is constant from the fault point F to the power source.

Since the fault voltage Vu is equal to the voltage drop caused by the fault current Iu flowing through the power transmission line from the power supply 2 at both ends to the fault point F, it can be seen that the fault voltage Vu is proportional to the distance from the fault point F.

That is, assuming that the distance from the measurement point P of the fault voltage Vu and fault current U to the fault point F is X, and the power transmission line impedance per unit length is 21, equation (1) holds true.

Vn=Zt −X −1n (A) ・(1)
Equation (1) applies when the measurement point P is located in the section 8 in Fig. 3, and when the measurement point P is located in the section 8, the phase of lu is opposite, so (' 2J formula % formula % (2
) However, Iu (A>, Iu (8>) are the intervals to each,
This is the fault current flowing through section B.

Here, let φA and φB be the phase difference between the fault voltage ■u and the fault current 1u in the 8 sections and the 8 sections, respectively, and then the equation (1) is obtained.
From equation 2), equation 3 is obtained.

φA-ara (Zt-X) φB =-aro (Zt-X) ””
(3) Generally, since 21 can be approximated as a series connection of a resistance and an inductance, the equation (4) is obtained.

O°≦ar(+(Zt)≦90° −(4)(3
As can be seen from the equation, it can be determined whether the measurement point P belongs to the F section or the B section based on the phase difference φ between the fault voltage Vu and the fault current In. That is, O゛≦φ≦90': A section - 180°≦φ≦-90'' C: B section ... Next, the ratio of the absolute value IVul of the fault voltage Vu and the absolute value IIul of the fault current ■U is IZM, it can be easily seen that the following relationship holds true with the absolute value IZtl of the power transmission line impedance 21 per unit length.

IZF 1-IZt l-X -164 Since IZtl is uniquely determined for the transmission line, lVu'1.1I
By calculating IZFI from ul, the distance X from the measurement point P to the failure point P can be located.

[Example] Embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram of the configuration of a failure point locating device 5 based on the present invention.

Current detector 51 for each of the three phases. Voltage detector 52° phase difference detector 53. Impedance meter 54. Comparator 5
5. Fault direction locator 56. A failure distance meter 57 and a trigger generator 58 are installed, and the information on each phase and the information on the timer 59 are configured to be input to a recorder 60.

The operation of the failure point locating device 5 according to the present invention is as follows.

The current and voltage of each phase of the power transmission line are measured by a current detector 51 and a voltage detector 52, and the measured values are input to a phase difference detector 53. The phase difference detector 53 determines the phase difference between the two, and the failure direction locator 56 locates the failure direction based on the value of the phase difference and inputs it to the recorder 60.

On the other hand, the impedance meter 54 calculates the impedance from the measurement point to the failure point based on the output ratio of the current detector 51 and the voltage detector 52, and the failure distance meter calculates the failure distance from the impedance per unit length given in advance. Input to recorder 60.

Note that the outputs of the fault direction locator 56 and the fault distance meter 57 are as follows:
The trigger signal is generated only when the trigger signal is generated by the trigger generator 58, and the trigger generator 58 is configured to generate the trigger signal only when the trigger signal is generated by the current detector 5.
Set to operate when the output of 1 exceeds a certain threshold. Comparator 55 is for setting the threshold value.

In the above configuration, the current detector 51 and the voltage detector 5
In addition to using a normal CT as the detection section 2, an optical element such as YIG that uses the Faraday effect or an optical element such as BGO that uses the electro-optic effect may be used. In this case, an optical fiber is used as the information transmission path. Code can be used. By configuring the detection section only with an optical system, there is no induction of lightning or the like, resulting in excellent reliability.

The embodiments described above are for ground fault accidents, but
Fault points can be located using exactly the same principle for phase-to-phase short circuit accidents. That is, a phase-to-phase potentiometer 521 may be provided after the voltage detector 52 in the configuration block of FIG. 1, and the configuration shown in FIG. 2 may be used as the voltage detection section of FIG. 1.

[Effects of the Invention] According to the present invention, the direction of the fault can be located based on the phase difference between the current and voltage of the faulty phase, and at the same time, the distance from the orientation point to the fault point can also be located based on the ratio of the absolute values of the current and voltage. Therefore, highly accurate orientation is possible. In addition, since it is sufficient to install the fault direction locating device based on the present invention at at most one location in each branch of the system, compared to the conventional method of installing each steel tower, etc.
Equipment costs are low because a long transmission line is not required and the number of devices is small.

When the present invention is utilized for locating fault points in a long power transmission system with many branches, or in a system with varying installation methods, it is believed that its true essence will be clearly demonstrated.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of a failure point locating device based on the present invention, and FIG. 2 is a partial explanatory diagram of the configuration for dealing with short circuits between phases.
Figure 3 is a model diagram of a single-line power transmission system. FIG. 4 is a diagram showing the distribution of fault current and fault voltage in the case of a phase fault. 1...Shipping? [l path, 2...power supply. 51... Current detector, 52... Voltage detector. 522... Phase difference potentiometer, 53... Phase difference detector. 54... Impedance meter, 55... Comparator. 56... Fault direction locator, 57... Fault distance meter. 58...The bird is the generator, 60...The recorder. Agent Patent Attorney Fujio Sato No. 1 Concave helmet 21 yen] Short 3 l Shadow 4 concave procedure amendment writing method) 60. ',. ,. 3rd Showa year
time

Claims (2)

[Claims] (1) In the method of locating fault points on power transmission lines, phase currents and phase voltages are measured from any position on a power transmission line consisting of multiple phases, and the phase current and phase voltage are determined between the phases determined to be faulty phases. A fault characterized in that a phase difference is determined, a fault direction is located from the phase difference, and at the same time, a distance from a measurement point to a fault point is located by finding a ratio of the absolute values of the phase current and phase voltage of the faulty phase. Point orientation method. (2) The fault point locating method according to claim 1, characterized in that immediately after measuring the phase voltage, the phase voltage is converted into an inter-phase voltage, and the phase current and the inter-phase voltage are used.