Same-tower double-circuit direct current transmission line fault line selection method based on single pole information

Abstract

The invention discloses a same-tower double-circuit direct current transmission line fault line selection method based on single pole information. The method includes the following steps: 1. voltage variations of four polar lines are calculated; 2. if the upper layer polar lines satisfy conditions, step 3 is carried out, and if the lower layer polar lines satisfy conditions, a step 4 is carried out; 3. If the low frequency harmonic wave amplitude satisfies a minimum value requirement, an amplitude ratio of low frequency and high frequency harmonic waves is continued to be obtained, if a specific value is larger than 1, the line of the pole is judged to be in fault, and otherwise travelling wave protection of the pole is locked; and 4. a voltage variation delay is sampled, if only one mutation wave head is detected in a data processing time window, the step 3 is carried out, if at least two mutation wave heads are detected in the data processing time window, polarity and amplitude relations of two continuous wave heads are compared, if the polarities are both positive and the amplitude relation satisfies a condition of a certain multiple, the line of the pole is judged to be in a non-near-end fault, and otherwise, travelling wave protection of the pole is locked. The same-tower double-circuit direct current transmission line fault line selection method based on single pole information has the advantages of high sensitivity, strong quick-action performance, difficult occurrence of misjudgment and the like.

Description

technical field [0001] The invention relates to a direct current transmission technology of a power system, in particular to a fault line selection method of a double-circuit direct current transmission line on the same tower based on unipolar information. Background technique [0002] The uneven distribution of natural energy in China and the asymmetric distribution of energy and population make HVDC transmission technology have broad application prospects in China. Compared with high-voltage AC transmission technology, high-voltage direct current transmission technology has the advantages of low unit cost, large transmission power, no need for synchronous operation of AC at both ends, and rapid control and adjustment. Therefore, the use of high-voltage direct current transmission technology is conducive to improving the economic and technical indicators of the power system , operational reliability and scheduling flexibility. [0003] In order to ensure the safe and relia...

AI Technical Summary

Problems solved by technology

However, since the double-circuit DC transmission lines on the same tower do not perform transposition, the polarities and amplitudes of the line-mode and ground-mode traveling wave components coupled out when different polar lines are grounded are different on each polar line, and the wave velocity It is not the same, which greatly increases the difficulty of identifying faulty polar lines in existing traveling wave protection schemes based on unipolar line information

If the above problems are solved only by increasing the setting value, the sensitivity of the protection will be affected. Therefore, it is necessary to make full use of the fault traveling wave propagation characteristics of the double-circuit DC line on the same tower to solve the problem.

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