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Based on the limitation of zero-sequence voltage compensation of traditional zero-sequence directional protection principle, an improved anti-maloperation protection strategy is proposed. First of all, by analyzing the characteristics of zero-sequence component, zero-sequence protection principle and maloperation reason of three circuits on the same tower, it is found that zero-sequence voltage over-compensation will change the polarity of zero-sequence voltage and lead to protection maloperation. Considering that the negative-sequence components are not affected by the mutual inductance between lines, a method of introducing negative-sequence components and reducing compensation impedance is proposed, which can reduce the possibility of over-compensating greatly. Based on this, the improved zero-sequence directional protection anti-maloperation logic is constructed. When a longitudinal fault occurs on the line, this method can achieve the purpose of preventing maloperation accurately. Finally, the effectiveness and feasibility of the proposed method are verified by numerical simulation.

Anti-maloperation Study of Zero-sequence Directional Protection for Three Circuits on the Same Tower