Common-tower double-circuit line vertical fault zero sequence pilot protection error operation prevention method

Abstract

The invention relates to a common-tower double-circuit line vertical fault zero sequence pilot protection error operation prevention method. The method comprises steps that zero sequence criteria are constructed and comprise main zero sequence direction criteria and zero sequence current start criteria; negative sequence criteria are constructed and comprise negative sequence direction auxiliary criteria, negative sequence compensation voltage start criteria, negative sequence current start criteria and a negative sequence voltage threshold; if the zero sequence criteria and the negative sequence criteria are simultaneously satisfied, a fault is determined to be a positive direction fault; if the zero sequence criteria are satisfied, the negative sequence current start criteria are not satisfied, and the negative sequence voltage threshold is satisfied, and the fault is determined to be an internal fault of an outgoing wire of a weak power source and is further a positive direction fault; if two ends of the line are determined to have positive direction faults, an internal ground fault of the line is generated, and a protection outlet is tripped. The method is advantaged in that through introducing negative sequence components and improving a compensation voltage, a zero sequence pilot protection error operation problem of a healthy line during generation of the common-tower double-circuit line vertical fault can be effectively prevented.

Description

technical field [0001] The invention relates to the field of relay protection of electric power systems, and more specifically relates to a method for preventing maloperation of longitudinal fault zero-sequence longitudinal protection of double-circuit lines on the same tower. Background technique [0002] Line zero-sequence longitudinal protection, as the main protection for line single-phase ground fault through transition resistance, is widely used because of its simple principle and high fault discrimination sensitivity. At the same time, when the zero-sequence longitudinal protection is configured on the double-circuit line on the same tower, due to the dual effects of electrical coupling and magnetic coupling, the zero-sequence longitudinal protection is directly affected by the operation mode of the system, and its reliability is threatened. For this problem, previous literatures have paid more attention to the operating characteristics and improvement measures of the...

AI Technical Summary

Problems solved by technology

At this time, if the existing zero-sequence longitudinal protection logic is still used (typical logic is after voltage compensation conditions are met, press 2 / 3Z 0 To compensate, Z 0 is the zero-sequence impedance value of the whole line), it will happen that the zero-sequence directional elements at both ends of the sound line are judged to be positive at the same time due to zero-sequence voltage overcompensation, which will lead to protection misoperation

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