JPH0226218A - Detecting method for short-circuit trouble zone of transmission line - Google Patents

Abstract

PURPOSE:To detect a short-circuit trouble zone without information transmitting means between iron towers by discriminating the direction of the short-circuit trouble point of both end power source system by a sensor mounted near a power line of specific phase of the tower or a support. CONSTITUTION:A voltage sensor K, a current sensor P are provided near 3-phase AC power lines A, B, C, the output of the sensor P is input to the comparator 2 of a phase comparator 1, and when it is larger than a reference voltage, a zero-cross comparator 4 is operated. The comparator 4 waveform- shapes the waveforms of the sensors P, K at a zero-cross point. An AND circuit 6 compares the phases of both, and operates an indicator 9 by an integrator 7, a display circuit 8 if both are in phase.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention detects the section where a short-circuit accident has occurred in a power supply system with both ends, by detecting the output generated by a voltage sensor or current sensor installed on a support such as a steel tower. It relates to a method of determining and detecting only information within the tower based on the phase of the waveform.

[Conventional technology]

Conventionally, when an accident occurs in a power system, the methods for detecting it are generally to detect zero-sequence voltage using a potential transformer or a grounding transformer, and to detect zero-sequence voltage using a current transformer or zero-sequence transformer. Zero-sequence current is being detected.

However, the higher the voltage, the higher the dielectric strength of these devices, and the larger the current capacity, the larger the size, and they are more expensive, so they are not used for both meters and protective relays. It is often done.

For the purpose of easily detecting zero-sequence voltage, the present applicant previously devised and filed an application for a zero-sequence voltage detector having the following configuration (Utility Model Application No. 41866/1983). In other words, multiple or single electrode bodies for ground detection are provided at right angles to the power lines of the three-phase AC power line and at intervals that are sufficient to withstand the pressurized voltage of each phase power line. Adjust the capacitance between each power line and the electrode body so that the combination of the potentials generated in the electrode bodies or the potential of a single electrode body becomes zero or very small when the voltages of each phase of the power line are equal. This is a zero-sequence voltage detector configured to detect the grounding of a power transmission line by detecting the voltage generated between an electrode body and the ground when a zero-sequence voltage is generated on the power transmission line.

In addition, for the purpose of detecting zero-sequence current, the applicant has previously developed a zero-sequence current detector with the following configuration and filed an application (Utility Model Application No. 141B67). A magnetic sensor with a coil placed in the center of a long and thin iron core is used to form a magnetic path that detects the magnetic field generated by the current flowing through the wire. Install the magnetic sensor on the outside of the square, at right angles to the power line, so that the longitudinal direction of the magnetic sensor is horizontal, and at a distance that is sufficient to withstand the pressure voltage of each Japanese-style room force line. This is a zero-phase current detector in which the constants of the magnetic sensor, such as the length of the iron core, the cross-sectional area, the number of turns of the coil, etc., and the position thereof are set so that the output voltage of the magnetic sensor is always zero or very small.

When such a zero-sequence voltage detector and zero-sequence current detector are used, the fault area can be detected by comparing the phase of the output waveform of the zero-sequence voltage detector and the phase of the output waveform of the zero-sequence current detector. Judgment can be made.

[Problem to be solved by the invention]

However, since this method detects the zero-sequence voltage using a zero-sequence voltage detector, it can only be applied to ground fault detection.
This method could not be applied to short circuits where zero-sequence voltage does not occur.

The present invention has been made in view of such conventional problems, and an object of the present invention is to detect a short-circuit section in a power transmission line with a power supply system at both ends using only a pylon on which a sensor is installed.

[Means to solve the problem]

In order to achieve this objective, the method for detecting a short circuit fault section of a power transmission line of the present invention involves winding a coil around the center of a rod-shaped core and installing it at a specific height so that the horizontal and longitudinal direction is perpendicular to the power line. It is characterized by detecting the direction of the short-circuit failure point by comparing the phase of the output voltage of the detection sensor and the output of a voltage sensor installed near a specific phase within the tower.

[Effect]

The phase of the voltage waveform appearing on the voltage sensor installed near a specific wire in the transmission line tower and the phase of the detected waveform of the current sensor installed at an appropriate position inside the tower may be in phase or opposite during a short circuit. There is a correlation.

This phase relationship means that there is a 180 degree difference on both sides of the short circuit point, so by measuring the phase difference between the outputs of the voltage sensor and the horizontal current sensor, the direction of the short circuit point can be detected and the fault area can be determined. It can be performed.

〔Example〕

Hereinafter, the present invention will be specifically described based on embodiments shown in the drawings.

FIG. 1 shows an example of how to attach a voltage sensor and a current sensor in the case of one line. A, B, and C are Japanese-style force lines of a three-phase AC power transmission line, K is a voltage sensor having an electrode body, and P is a horizontal current sensor having a coil wound around a rod-shaped core.

Va
-VC, and a voltage sensor K is installed at a location where Vb > v, for example, at a location where V, = V, /2. Further, the current sensor P is installed so that the longitudinal direction of the core is perpendicular to the line of force in the Japanese-style room B and parallel to the ground.

By installing in this manner, even in the event of a short circuit, the voltage sensor K provides an output corresponding to the ground voltage, and the current sensor P provides an output corresponding to the short circuit current.

By detecting the phase relationship between these outputs, the fault area is determined.

The operation will be explained by taking as an example the case where there is a short circuit between the A phase and B phase.

FIG. 2 shows a vector diagram when a short circuit occurs between the A and B phases. B The voltages induced from each Japanese-style room force line during normal operation are measured by the voltage sensor K installed near the Japanese-style room force line as Vay and V, respectively.
bk and Vck, and when the A and B phases are short-circuited, the voltage induced in the voltage sensor K from each Japanese-style room force line is V a
Let N+Wbi+Vcs be the short circuit current between the A phase and B phase. Note that V a k and the like are vector r quantities, and a dot is placed above them to distinguish them from the scalar ■.

The presence or absence of a short circuit accident is determined by comparing the output levels of the i-yellow type current sensor P, and the short circuit section is detected by comparing the phases of the output waveforms of the current sensor P and the voltage sensor.

Now, 9□, νb l + V e I, assuming that the positive phase impedance and negative phase impedance are almost equal, v, Sl = l Vat + l/2, l Vbs
l = l Vbk l /2, VC$=VCk, and the direction of Va%+Vbs is opposite to the direction of Vek. Therefore, the output voltage 9 of the voltage sensor is a composite voltage of Vas+Vhs+Vcs, and Vk=V-.

Moreover, since the generator impedance immediately after a failure is mostly an inductance component, the short circuit current I abs lags approximately 90 degrees from the direction from the A phase to the B phase, and the voltage sensor output 9. The phase is almost reversed.

Since the horizontal current sensor P has its elongated direction facing the B-Japanese-style room power line, it does not respond to the B-phase current and only responds to the induced voltage due to the short-circuit current f abl flowing in the A-phase power line, resulting in an output of 9.
．． appears, and its phase is almost opposite to that of the output to the voltage sensor.

FIG. 3 shows how a fault current flows when a short circuit occurs between the A phase and B phase in the power transmission line of the power supply system at both ends.

FIG. 4 shows electromagnetic induction exerted on the horizontal current sensor P.

Assume that both substations SS, X and Y, have power supplies, and a short-circuit failure between phases A and B has occurred at point F. X from point F
When a voltage sensor K and a horizontal current sensor P are installed at point p near the end and point q near the Y end as shown in Fig. 1, p
The output power of each voltage sensor at point and point q. , VMq and short-circuit current f, , 12 are shown in FIGS. 5(a) and (b), respectively.
), the phase is reversed. However, a short circuit current of 11. A short circuit current t2 flows from the Y end, ! l and 12
As shown in Figure 4, the induction to the horizontal current sensor is in the opposite direction at point p as shown in Figure 4 (a) and at point q as shown in Figure 4 (b). The current sensor output Vp has opposite phases at point p and point q. Therefore, the phase difference θ between the outputs V kp , V K Q of the voltage sensor and the output V p p +v8 of the horizontal current sensor is as shown in Fig. 5 (a) at point p and the same at point q. Figure (b)
There are about 180 different variations.

In this way, the output of the voltage sensor and the output of the horizontal current sensor are 9. By measuring the phase difference angle with respect to the sensor, it can be determined whether the short circuit point is on the X end side or the Y end side of the steel tower where the sensor is installed.

FIG. 6 shows an example of the configuration of a detection system that implements the short circuit section detection method of the present invention. In the figure, the output voltage of a current sensor P is input to a comparator 2 of a phase comparator 1. Comparator 2 compares the output voltage of current sensor P and a reference voltage determined by resistor 3. Sensor P
When the output voltage is large, the zero cross comparator 4 is activated.

The zero-cross comparator 4 shapes the waveforms of the output voltages from the current sensor P and the voltage sensor at zero-cross points, and the AND circuit 6 performs phase comparison. If the waveforms of the output voltages to the current sensor P and the voltage sensor are in phase, the integrator 7 and the display circuit 8 operate the display 9.

Note that since the present invention utilizes the B-phase voltage for neutralization, it can also be applied to an ultra-high voltage reverse phase arrangement system.

The present invention can also be applied to multi-line towers by installing sensors on each line.

Furthermore, in the present invention, since the phase difference of the sensor output is close to 180 degrees, it is sufficient to detect whether it is 0 degrees or 180 degrees, and there is no need for detailed comparison, so the comparator is simplified and reliability is improved.

〔Effect of the invention〕

As described above, in the present invention, the phase of the voltage at the time of a short circuit detected by the voltage sensor installed near the power line of a specific phase of the tower or support, and the phase of the voltage detected by the horizontal current sensor By comparing the phase of the short-circuit current, the direction of the short-circuit fault point in the both-end power supply system is determined. Thereby, the direction of the short-circuit point can be detected by the steel tower alone, and therefore, the short-circuit fault section can be detected even without information transmission means between the steel towers.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of installing voltage sensors and current sensors in the case of one line, Figure 2 is a vector diagram of each phase in the case of a short circuit,
Figure 3 is an explanatory diagram showing how fault current flows when a short circuit occurs in the power supply system at both ends. Figure 4 is an explanatory diagram of electromagnetic induction affecting a horizontal current sensor. Figure 5 is an illustration of the phase difference between the outputs of the voltage sensor and current sensor. FIG. 6 is a block diagram showing an example of the configuration of a system for implementing the method of the present invention. A, B, C: For each Japanese room force line of 3-phase AC power transmission line: Voltage sensor P: Current sensor 1: Phase comparator
2: Comparator 3: Resistor 4; Zero cross comparator 5: Differentiating circuit 6: AND circuit 7: Integrating circuit

Claims (1)

[Claims] 1. The output voltage of a short-circuit current detection sensor, which has a coil wound around the center of a rod-shaped core and is installed at a specific height so that its longitudinal direction is horizontal and perpendicular to the power line, and the vicinity of a specific phase in the tower. 1. A method for detecting a short-circuit fault section of a power transmission line, the method comprising: detecting the direction of a short-circuit fault point by phase comparison with the output of a voltage sensor installed in a power transmission line. 2. A short-circuit fault in a power transmission line characterized by detecting a short-circuit fault section by comparing the phases of the outputs of a voltage sensor and a current sensor installed in the vicinity of a power line of a specific phase in a steel tower in a power supply system transmission line at both ends. Interval detection method.