Method for judging inrush current locking of equivalent instantaneous inductance for protection of extra-high voltage regulating transformer

Abstract

The invention discloses a method for judging inrush current locking of an equivalent instantaneous inductance for protection of an extra-high voltage regulating transformer belonging to the technical field of relay protection of a power system. The method comprises the steps as follows: firstly, calculating action currents and brake currents of A phase, B phase and C phase of the extra-high voltage regulating transformer, and judging if the phases enter into action areas of ratio brake characteristics by comparing the action currents and the brake currents; for the phases entering into the action areas, calculating a voltage of an equivalent port of the voltage regulating transformer according to the voltage on the medium-voltage side of a main transformer in the extra-high voltage transformer by utilizing a voltage transformation method, and calculating the equivalent instantaneous inductance variances sigma Li of the phases; and if the equivalent instantaneous inductance variances are higher than a threshold value epsilon, namely sigma Li > epsilon, judging that the phases generate an inrush current, locking the phases for protection, otherwise, judging that the phases have a failure, and finally outputting a judgment result. According to the method, the identification problem of the inrush current and an inter-turn / turn ground failure when the extra-high voltage regulating transformer is deeply saturated is emphatically solved, the essential difference of the failure and the inrush current is reflected, and the reliability for protection of the extra-high voltage regulating transformer is effectively improved.

Description

[0001] Patent field [0002] The invention belongs to the technical field of relay protection of electric power systems, and in particular relates to an equivalent instantaneous inductance inrush blocking discrimination method for UHV voltage regulating transformer protection. Background technique [0003] UHV power transmission is a new business in the field of power grid development in the world, and it is at the forefront of grid technology development. At present, there is no mature experience at home and abroad. The 1000kV UHV transformer has a special structure. It consists of two parts: the main transformer and the voltage regulating transformer. The high, medium and low voltage sides of the main transformer adopt the winding connection mode of Yn, Yn and d11. The voltage is 1050 / 3:525 / 3±4×1.25%:110kV, and adopts the neutral point non-excitation voltage regulation method, which is very different from the traditional transformer structure, especially the split regulation...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problem of insufficient reliability of the differential protection of the above-mentioned UHV voltage regulating transformer, and propose a method for judging the equivalent instantaneous inductance inrush current blocking of UHV voltage regulating transformer protection. The UHV voltage regulating transformer consists of three independent Composed of single-phase transformers, the Y-Δ wiring method is adopted, and the TA5 installed on the secondary side is connected to the inside of the Δ side winding. Therefore, there is no phase difference in the measured primary and secondary currents, and the accurate differential current i can be obtained directly d ;

Images