Overload anti-misoperation and high-resistance line phase-to-phase fault distance protection method

Abstract

The invention discloses an interphase fault distance protecting method for overload maloperation-preventive and anti-high-resistance lines. The interphase fault distance protecting method includes: firstly utilizing fault interphase voltage, fault interphase current and fault interphase negative-sequence current at a power transmission line protection installation point to calculate line distance between the power transmission line protection setting range to an interphase short-circuit fault point, judging whether the line distance between the power transmission line protection setting range to the interphase short-circuit fault point is larger than zero or not, if yes, judging that the interphase short-circuit fault point is within the power transmission line protection setting range, and sending out an action trip signal to trip off breakers at two ends of the power transmission line. By the interphase fault distance protecting method, influence on protective action performance from transition resistance is eliminated theoretically, and strong resistance to affection of the transition resistance is provided.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for protecting fault distances between phases of lines with overload prevention, maloperation and resistance to high resistance. Background technique [0002] Since distance protection is less affected by power system operation mode and structural changes, it can selectively remove various faults in transmission lines instantly, and has been widely used in power system transmission line protection. The distance protection on the high-voltage transmission line is used as the main protection of the transmission line, and the distance protection on the EHV / UHV AC transmission line is used as the backup protection of the transmission line. At present, the distance protection widely used in power system transmission lines mainly includes power frequency variation distance protection and impedance distance protection. [0003] The power frequenc...

AI Technical Summary

Problems solved by technology

[0005] However, the action performance of impedance distance protection is seriously affected by the transition resistance. The main performance is that if the additional impedance generated by the transition resistance is resistive and inductive, it is easy to cause the impedance distance protection to refuse to operate when there is a fault in the protection zone of the transmission line; if the additional impedance generated by the transition resistance is resistive Capacitance is easy to cause the impedance distance protection action to exceed when there is a fault outside the protection zone of the transmission line

[0006] Over / extreme voltage AC transmission lines are often also heavy-duty transmission lines. Heavy-load currents will cause impedance distance protection to malfunction or refuse to operate. The impact of heavy-load current on the performance of impedance distance protection cannot be ignored.

Under the condition of overload transmission, the transmission line has no faults. The measured impedance of the traditional distance protection will seriously deviate from the actual measured impedance due to the influence of the overload current, which will easily lead to the misoperation of the traditional distance protection, which will cause the power grid to expand the scope of power outages, and even cause large load transfers to threaten other transmissions. The normal operation of the line has brought huge potential safety hazards to the safety of the power grid

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