Method for blocking elements in zero-sequence direction for double-circuit lines on same tower

Abstract

The invention discloses a method for blocking elements in a zero-sequence direction for double-circuit lines on the same tower. According to the method, a protection device in a longitudinal direction samples a current waveform of a current transformer of the double-circuit lines on the same tower and extracts a zero-sequence current component and a positive-sequence current component; and when the protection of the protection device in the longitudinal direction is started, the protection device in the longitudinal direction judges if a ratio of the zero-sequence current component to the positive-sequence current component is less than 15% of a starting threshold, if so, the fault type is judged as an inter-phase ungrounded fault and the elements in the zero-sequence direction are blocked, if not, the fault type is judged as a grounded fault, and the elements in the zero-sequence direction are put into protection judgment. The method disclosed by the invention can correctly distinguish the grounded fault and the inter-phase ungrounded fault of the double-circuit lines on the same tower and prevent the elements in the zero-sequence direction from being wrongly started for the inter-phase ungrounded fault so as to further prevent missed protection or wrong protection.

Description

technical field [0001] The invention relates to the technical field of longitudinal direction protection on double circuit lines on the same tower, in particular to a method for blocking zero-sequence directional elements on double circuit lines on the same tower. Background technique [0002] Pilot directional protection The main protection consists of distance directional elements and zero sequence directional elements. Zero-sequence directional elements include zero-sequence forward elements and zero-sequence reverse elements. After the protection is started, if the zero-sequence voltage and zero-sequence current where the protection is located reach the start threshold of the zero-sequence directional element, the zero-sequence directional element starts to participate in the fault direction discrimination. If any of the zero-sequence voltage and zero-sequence current does not reach the starting threshold, the zero-sequence directional element will not start, and only t...

AI Technical Summary

Problems solved by technology

At this time, the zero-sequence directional element may start by mistake because both the zero-sequence voltage and zero-sequence current reach the start-up threshold, and the fault direction cannot be correctly judged, which will eventually cause the protection to refuse to operate or malfunction

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