Direct current transmission line fault detection method and system

Abstract

The invention relates to a direct current transmission line fault detection method and system, and belongs to the field of power system relay protection. The method comprises the following steps: firstly, collecting single-end electrical quantity data of a direct-current line in real time to obtain a spatial modulus signal of the single-end electrical quantity; calculating the cumulant of the power transformation of the space modulus signal variable quantity of the single-ended electrical quantity in a set time window, and constructing a fault detection signal; and continuously judging at least three adjacent fault detection signals, judging whether the fault detection signals are all greater than a set detection threshold value or not, if not, returning to continue to collect and calculate the single-end electrical quantity, and if yes, determining that the line has a fault, and sending out a protection starting signal. The invention also provides a DC line fault detection system. The method provided by the invention can quickly and reliably detect the line fault, and has the advantages of sensitivity, reliability and quickness.

Description

technical field [0001] The invention relates to a DC transmission line fault detection method and system, belonging to the field of relay protection of electric power systems. Background technique [0002] With the rapid development of my country's economy, AC transmission can no longer meet the electricity demand of our residents. Since my country's energy distribution and power load demand distribution are inversely phased, DC transmission lines have become the main direction of my country's power transmission development in the future due to their advantages such as large capacity, long transmission distance, and convenient grid interconnection. After the DC transmission line fails, the DC system will be blocked due to protection malfunction, which will lead to unnecessary outage of the DC transmission system. In addition, most of the DC lines are arranged in remote mountainous areas, where the natural environment is relatively harsh and maintenance is extremely inconven...

AI Technical Summary

Problems solved by technology

Among them, the traveling wave protection is the main protection of the DC line, and its advantage is to determine the fault line quickly and accurately; the differential undervoltage protection is not only the main protection of the DC line, but also the backup protection of the traveling wave protection. For traveling wave protection, the protection speed is slow but the sensitivity and reliability are high, but the above two protections have the technical problem that the protection will malfunction in high-impedance faults, which has not been resolved.

Low voltage protection is the backup protection of traveling wave protection and differential undervoltage protection. This protection is divided into line low voltage protection and pole control line voltage protection. Its advantage is that high resistance faults that cannot be cut off by traveling wave protection and differential undervoltage protection , but there is a problem that it is impossible to distinguish what is an internal fault and what is an external fault

The longitudinal differential protection is the backup protection of the DC transmission line. Its advantage is that it can reliably cut off the high-resistance fault, but there is a problem that any voltage change may cause the protection to malfunction without considering the capacitive current.

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