TH1102A - Tools and methods for power transmission system protection - Google Patents

Abstract

This invention provides a method and instrument for detecting short-circuits between any phase, one phase and earth in a three-phase power system. And for detecting the phase that has caused a short circuit too That is, can It is used to correctly isolate any phase-to-earth short-circuit from any other short-circuit, including phase-to-phase-to-earth short-circuits, even if the transmission line has capacitors per series. This is achieved by considering the voltage between phase and phase. Which is perpendicular to the voltage between the monitored phase and earth.

Claims (1)

1. A short-circuit detector between any phases in a three-phase system consists of: - - The first phasor signal generator that responds to the current. Asymmetrical in a three-phase system - the device generates a second phasor signal, which indicates Negative sequence volume Reference to the phase being monitored - the third phasor signal generator that responds to The phase voltage being monitored - A device used to compare the phase angles of the second and third phasor contracts. By equipment used In the aforementioned comparison, a signal that indicates Short-circuit in a three-phase system where the short-circuit occurs in the power phase. It is monitored when the phase angle is correlated in a predetermined manner. 2. Short-circuit detector according to claim 1, where the quadrature voltage is line to line voltage with the phase angle at Is perpendicular to the phase angle of the phase voltage being monitored. 3. Short-circuit detector according to claim 1, in which the defined relationship characteristics of the phase angles are all within a specified number of electrical degrees from 4. Short-circuit detectors according to claim 3, the number of electrical degrees set equal to 60 degrees 5. Short-circuit detectors according to claim 1, where the comparator compares the signal coincidence. According to the specified polarity of the first, second and third signals, and that the comparator generates the output signal when the coincidence Each of the terminals that are the same beyond the specified time. 6. Equipment according to Clause 5, which time period has been defined. The electrical degree is equal to 120 degrees. 7. Short circuit detector according to claim 1. The negative sequence quantity is the wind sequence. 8. Short-circuit detector according to claim 1, where the negative-sequence quantity is the negative-sequence voltage at the phase changing at a + j rate. 9. What phase-to-phase short-circuit detector in the system. Three-phase power comprising phases A, B and C, VA, VB and CC voltages, VAB, VCA and VBC inter-phases, and phase currents IA, IC, and IB, and for detection of phases occurring by detectors. The short-circuit consists of: - - The first phasor generating device that responds to the sum of the phase currents IA, IB and IC - the second, third and fourth phasor generating devices that respond to the sequence quantity. Negative that refer to A, B, and C phases, respectively - the fifth, sixth and seventh phasor generating devices that respond to VBC, VCA and AAB respectively - the first monitoring device to generate the signal. Export shown To the short-circuit between phase A and earth when the first, second and fifth phasor signals have degree differences. The required amount of electricity - second monitoring device To generate the output signal at Represents the short-circuit between phase B and earth when the first, third, and sixth phasor signals are different. Of the specified number of electrical degrees, and - the third monitoring device To generate the output signal at Denotes a short-circuit between phase C and earth when the first, fourth and seventh phasor signals differ from The specified number of electrical degrees 1 0. Short circuit detector according to claim 9, the specified number of electrical degrees is equal to 60 degrees 1. 1. A method for detecting a short-circuit between any phases. A three-phase electrical system consists of the following steps: - - Generating the first phasor signal that responds to the sum of Three-phase currents in a three-phase system, - generation of a second phasor signal indicates a quantity Defined negative sequence With reference to the phase being monitored - generation of the third phasor signal Responding to the force The phase voltage being monitored - a comparison of the phase angles of the aforementioned first, second and third phasor signals - and signal generation indicating an inter-phase short circuit. When the phase angle comparison phase detects a correlated phase angle. In the specified manner (11 claims, 3 pages, 13 photos)