Transmission line micro processor adaptive split-phase longitudinal difference protection method

Abstract

In the invention, protection is realized by comparing with current amplitudes and phases at two ends to brake unbalanced current on transmission line. The method includes steps: multiplying current at local end and current at remote end by coefficient, adding two calculating results; rotating the added current vector 90 degrees widdershins so as to obtain transformed amplitude of current vector; next, multiplying transformed amplitude of current vector by amplitude of current vector at local end; then, multiplying result obtained at previous result by sinusoidal quantity of included angle between local current and current at opposite end to obtain braking action quantity. The method selects action equation based on change of included angle between currents at two ends so as to prevent too large phase angle difference of currents between two ends.

Description

technical field [0001] The invention relates to the field of relay protection for power system transmission lines, in particular to a method for realizing the longitudinal differential protection of transmission lines by using a microcomputer. Background technique [0002] Usually, the current longitudinal differential protection of the transmission line uses the communication channel to connect the protection devices at both ends of the transmission line longitudinally, and transmits the electrical quantity (current, power direction, etc.) at each end to the opposite end, and compares the electrical quantities at both ends. To judge whether the fault is within the range of the line or outside the range of the line, so as to decide whether to brake (or cut off) the protected line. This is the most complete protection method in the field of transmission line differential protection. However, the existing current longitudinal differential protection ...

AI Technical Summary

Problems solved by technology

[0006] Compared with the prior art, the present invention proposes a microcomputer self-adaptive phase separation longitudinal differential protection method for transmission lines. The positive effects that this method can produce are: first, the present invention realizes current differential protection and obtains excellent braking characteristics; secondly, the present invention adopts microcomputer technology to realize self-adaptive processing, and can select different action equations according to the variation range of the angle between the currents on both sides, which solves the internal short circuit and the excessive phase angle difference between the currents on both sides makes the protection subject to braking It has a high degree of reliability, which can not only increase the braking amount when external faults occur, but also increase the braking sensitivity when internal faults occur; there is no restriction on the selection of the braking coefficient, so it has a poor influence on the general situation The factors of dynamic protection (such as the error caused by the saturation of the current transformer and the distributed capacitance of the line, etc.) can be easily solved by increasing the braking amount. Complete the braking of the local end and the opposite end to achieve a complete protection effect at each end of the transmission line

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