FIELD: electricity.
SUBSTANCE: protected line is divided into double-end sections: head section from buses to switchboards at each line end, and intermediate sections between switchboards at the line ends. Voltage dip is measured and compared by same value and polarity principle at both ends of each intermediate and head section at equal rated distance from each section end of each uniform power cable in the line with unidirectional through current flowing in this cable. Short circuit outside of the section is detected by similar (coinciding) voltage dip value and polarity, and internal short circuit in the section and hence in the line is detected by different voltage. Instruments for required operations, uninsulated from high-voltage potential of power cable, and primary windings of power supply unit transformers for power the instrument powering are connected parallel to the power cable. With short circuit detected, generator of high carrying frequency is launched at the section, and permanent storage device is activated with intermediate or head section number code stored in it, high-frequency oscillations of carrier frequency generator are modulated by code impulses, and code impulses filled with carrier frequency in such a pattern are transmitted over power cable section ends to all head sections or line ends. Secondary windings of power unit transformers are used to generate electrically insulated DC outputs. Additionally current measurement is performed for each power cable in each head section, high-frequency signal modulated by section code is singled out, then the code is filtered out of high carrier frequency, separated from high potential of power cable, e.g. by electronic-to-optic converter system, optic fibre line and optic-to-electronic converter. Damaged line, section and cable are determined by the code obtained. Line code is decoded, and obtained potential signal is used for disconnection of switchboards at each end of the line. Also code of damaged section and cable is decoded for visualisation for staff.
EFFECT: short circuit detection in a line with reduced line parametre influence on required protection properties, fixed indication of damaged point in line, operation of all data transfer instrumentation and controls at opposite line ends rather with potential of each controlled high-voltage power cable than with earth potential, improved organisation scheme of high frequency data exchange between protection packages.
4 dwg
