A short circuit current evaluation method based on the branch fault current of the circuit breaker

Abstract

With the rapid load growth and the increasing density of power grids， the overrun short-circuit current becomes increasingly aggravated. To accurately assess the short-circuit current level of the system is crucial to ensure the safe and stable operation of the power grid. Therefore， a short-circuit current evaluation method based on the branch fault current of the circuit breaker is proposed. In view of the double-bus double-section wiring substations at voltage levels of 220 kV and below and 500 kV three-to-two wire substations， the paper analyzes the short circuit current flowing through the circuit breaker in case of different fault locations， switch-off of circuit breakers， etc. Moreover， it proposes a calculation method of the short circuit current that the circuit breaker requires in the single-jump single-weight stage of single-phase fault occurring at the line outlet and determines the maximum short circuit current required to block the circuit breaker in the substation. Additionally， it specifies a short circuit current calibration standard that the maximum short circuit current flowing through the circuit breakers after the fault should not exceed their breaking capacities. Finally， the effectiveness of the proposed evaluation method is verified through case analysis.

Keywords

• short circuit current
• branch circuit breaker
• double-bus double-subsection wiring
• three-to-two wiring
• single-phase reclosing