Superconducting fault current limiter-based flexible direct-current transmission system current-limiting electric reactor selection method

Abstract

The invention relates to a superconducting fault current limiter-based flexible direct-current transmission system current-limiting electric reactor selection method, and belongs to the technical field of direct-current transmission. According to the method, when a direct-current side line fault occurs in a modularized multi-level flexible direct-current power transmission system, the current-limiting electric reactance of the direct-current line is calculated to be matched with the superconducting fault current limiter to inhibit the fault current so as to ensure that the fault removal can becompleted under the condition that a multi-level converter is not locked. According to the method disclosed by the invention, a calculation method for selecting the fixed impedance in a substituted mode is improved, and the resistance value of the superconducting fault current limiter is subjected to piecewise linearization fitting based on a least square method so as to optimize and solve. According to the method disclosed by the invention, the reasonable value-taking margin of the current-limiting electric reactor can be calculated under the influence of the dynamic resistance value of thesuperconducting fault current limiter, the system stability and the dynamic response capability can be effectively improved, and the method has guiding and reference meaning to the practical engineering in the future. According to the method disclosed by the invention, the cooperation between various primary equipment parameters is comprehensively considered, the primary equipment is more reasonably selected, the utilization efficiency of primary equipment is improved, the system investment cost is lowered, and the economical efficiency is improved.

Description

technical field [0001] The invention relates to a method for selecting a current-limiting reactance of a flexible direct current transmission system based on a superconducting current limiter, and belongs to the technical field of direct current transmission. Background technique [0002] The flexible DC transmission system (Voltage Source Converter-High Voltage DirectCurrent, VSC-HVDC) does not need to consider the frequency and phase of the connected AC system, the interference and influence between the interconnected systems are small, and the transmission power can be controlled quickly and accurately. It can effectively improve the stability of the system. However, compared with the AC system, due to the small impedance of the flexible DC system, the short-circuit current rises very fast when a fault occurs. With the fault current of the flexible DC system itself, there is no natural zero-crossing point, which makes it more difficult to clear the fault of the flexible D...

AI Technical Summary

Problems solved by technology

At this time, it is no longer applicable to use a fixed impedance value selected at a certain moment to conduct current limiting analysis at different fault stages, especially for the initial fault stage, the actual energy accumulation of the superconducting current limiter itself is insufficient and the impedance is too small, while the expected effect is relatively low. Optimistic, resulting in improper selection of current-limiting reactance and affecting system stability

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