Zero sequence voltage compensation component locking method and device of double circuit line on same tower

Abstract

The present invention provides a zero sequence voltage compensation component locking method and device of a double circuit line on a same tower. The method comprises the following steps: collecting a load current before a line fails, a zero sequence current after the line fails and a zero sequence voltage at a zero sequence voltage compensation component; establishing a first criterion according to the zero sequence current, establishing a second criterion according to the zero sequence voltage, and establishing a third criterion according to the zero sequence current and the load current; and when the zero sequence current meets a zero sequence directional protection starting condition of the first criterion, if the zero sequence voltage meets a locking condition of the second criterion, or the zero sequence current and the load current meet the locking condition of the third criterion, locking the zero sequence voltage compensation component. As compared with the prior art, according to the zero sequence voltage compensation component locking method of the double circuit line on the same tower, when one circuit line of the double circuit line on the same tower has an asymmetrical longitudinal fault, the malfunction of the zero sequence voltage compensation component of another circuit line is prevented, and reliable operation can be ensured when a ground fault occurs.

Description

technical field [0001] The invention relates to the technical field of electric power system transmission, in particular to a zero-sequence voltage compensation element blocking method suitable for long-distance double-terminal common bus lines and double-circuit lines on the same tower. Background technique [0002] Power system faults mainly include two types of faults: transverse faults and longitudinal faults. Horizontal faults refer to various types of short-circuit faults, including three-phase short-circuits, two-phase short-circuits, single-phase-to-ground short-circuits, and two-phase-to-ground short-circuits. Longitudinal faults refer to Various types of disconnection faults, including single-phase disconnection, two-phase disconnection and three-phase disconnection. When a transverse fault occurs on a long-distance transmission line, such as a ground fault at the end of the line or a high-resistance ground fault at the end of the line, the zero-sequence voltage co...

AI Technical Summary

Problems solved by technology

[0003] However, the zero-sequence voltage compensation method is mainly aimed at asymmetric transverse faults of transmission lines, and does not consider longitudinal faults of transmission lines

For example, when the upper circuit of the same tower with long-distance double-ended common bus transmits relatively large power, when an asymmetric longitudinal fault occurs on the primary circuit, a large zero-sequence imbalance will be generated on the faulty line and the non-faulty line due to power flow transfer. At the same time, there is also a zero-sequence mutual impedance between the double-circuit lines on the same tower, and its value can reach 50-70% of the line's self-impedance, resulting in a small shunt of the zero-sequence current on the fault line along the two ends of the system, and the two ends of the line The zero-sequence voltage is small, so it may cause false start-up of zero-sequence voltage compensation components and misjudgment of zero-sequence directional components on non-fault lines, thereby seriously endangering the safe and stable operation of the power system

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