An AC/DC fault identification and protection coordination method in a converter station

Abstract

The invention discloses an AC / DC fault identification and protection coordination method in a converter station belonging to the technical field of safe operation of an AC / DC hybrid transmission system. According to the characteristics of DC second harmonic current and AC negative sequence current before and after the converter lockout, the invention puts forward the converter station differentialcurrent protection, which can distinguish AC from DC faults, determine the fault area, and the coordination and cooperation scheme of AC and DC protection. Finally, combined with PSCAD / EMTDC model ofPV / DC convergent access system, the feasibility of differential protection and the reliability of AC / DC protection coordination scheme are verified. The results show that the proposed method can effectively identify AC and DC faults, and is less affected by the transition resistance.

Description

technical field [0001] The invention belongs to the technical field of safe operation of an AC-DC hybrid power transmission system, and in particular relates to an AC-DC fault identification and protection coordination method in a converter station. Background technique [0002] In the AC-DC hybrid system, in order to avoid damage to the force electronic switch due to faults, it is necessary to limit the fault current and isolate the fault quickly. A converter with fault isolation capability can be used or a current limiting device can be installed. In order to reduce the impact of faults on system operation, control strategies can be used to maintain the operation of the non-faulty part of the power grid. However, in order to reduce the impact of faults on the normal operation of non-fault lines and achieve rapid system recovery, it is still necessary to determine the fault area and complete fault isolation. The AC faults in the converter station are generally permanent f...

AI Technical Summary

Problems solved by technology

However, for DC protection, when the delay time is long, there may be cases where the fault feature disappears due to reasons such as converter blocking

Moreover, most of the existing AC and DC protections do not comprehensively consider the characteristics of AC and DC faults and the coordination of protection schemes and fixed values, and the function of determining the fault area still needs to be improved.

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