Adaptive re-switching-on method for flexible DC transmission system with DC circuit breaker

Abstract

The invention discloses an adaptive re-switching-on method for a flexible DC transmission system with a DC circuit breaker. The method comprises the steps of: after a DC fault occurs and the DC circuit breaker operates, ensuring the de-ionization of a fault line after a preset delay; in initiative cooperation with the circuit breaker, injecting, by a current converter, a voltage signal into the fault line by active control, detecting the polarity of reflected voltage, and if the polarity of the reflected voltage is the same as the polarity of the voltage signal, determining that the fault is atransient fault and re-switching on the fault line; if the polarity of the reflected voltage is opposite to the polarity of the voltage signal, determining that the fault is a permanent fault, not re-switching on the fault line and locating the fault. The adaptive re-switching-on method determines whether to re-switch on the circuit breaker by determining the fault property so as to prevent secondary impact on the system caused by re-switching on the circuit breaker in the event of the permanent fault, can clearly distinguish all fault types based on the polarity of the reflected voltage, andachieves high reliability.

Description

technical field [0001] The invention belongs to the field of flexible direct current transmission, and more specifically relates to an adaptive reclosing method for a flexible direct current transmission system including a direct current circuit breaker. Background technique [0002] Based on MMC (Modular multilevel converter), DC transmission technology with its modular structure, low harmonic content, self-starting, power decoupling control, low switching loss, etc. , asynchronous interconnection, urban power grid capacity expansion, power supply to passive systems, and connection to weak AC power grids have broad application scenarios. Considering the power transmission distance, voltage level and cost issues, flexible DC systems often use overhead lines for large-scale power transmission. The working environment of overhead lines is harsh, and the probability of failure is high; at the same time, the fault current rises rapidly and has a large amplitude, which will caus...

AI Technical Summary

Problems solved by technology

[0007] In view of the defects of the prior art, the purpose of the present invention is to provide an adaptive reclosing method for a flexible direct current transmission system including a DC circuit breaker, aiming at solving the problem of low reliability of the existing adaptive reclosing scheme

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