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] The main protection of longitudinal direction protection is composed of distance direction element and zero sequence direction element. The zero sequence direction element includes a zero sequence positive direction element and a zero sequence reverse direction element. After the protection is activated, if the zero-sequence voltage and zero-sequence current where the protection is located both reach the starting threshold of the zero-sequence directional element, the zero-sequence directional element starts and participates in the identification of the fault direction. If either of the zero sequence voltage and zero sequence current does not reach the start threshold, the zero sequence di...

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

Images