Control method for reducing converter station short-circuit current of two-end flexible direct-current power transmission system

Abstract

The invention discloses a control method for reducing converter station short-circuit current of a two-end flexible direct-current power transmission system. The size of short-circuit current provided by the flexible DC converter station, the control mode, the operation condition and the influence of an inner and outer loop controller amplitude limiter are comprehensively considered. According to the control method, the rapid response characteristic of the flexible DC converter is utilized while it is ensured that the flexible DC converter station is not locked; by adjusting an outer ring controller reactive shaft current reference value of a receiving end converter station, and controlling alternating current output by the converter station when the alternating current system is short-circuited, short-circuit current provided for a fault point when a near-region short-circuit fault of the receiving end converter station occurs is reduced, the short-circuit current level of the alternating current system is further reduced, and important reference significance is achieved for application of the flexible direct current power transmission technology in engineering in China.

Description

technical field [0001] The invention belongs to the technical field of flexible power transmission and distribution of power systems, and in particular relates to a control method for reducing the short-circuit current of a converter station of a flexible direct current transmission system at both ends. Background technique [0002] Flexible DC transmission is the third-generation DC transmission technology based on voltage source converter technology. Generally, the converter element used is a bidirectional controllable power electronic device that can control both conduction and shutdown. The typical representative is the insulation Gate Bipolar Transistor (IGBT). There are mainly three topologies of voltage source converters used in existing flexible HVDC projects, namely two-level converters, diode-clamped three-level converters and modular multilevel converters ( MMC); Each bridge arm of a modular multilevel converter cascaded with sub-modules (SM) is composed of multi...

AI Technical Summary

Problems solved by technology

[0005] When there is a short-circuit fault in the AC system near the DC converter station, especially at the PCC, there are generally two measures to reduce the short-circuit current provided by the converter station: one is to block the converter station. On the AC side, it is equivalent to an open circuit and will not provide short-circuit current, but the process of restarting after the converter station is blocked is cumbersome and time-consuming; the other is to limit the short-circuit through appropriate control measures when the DC converter station is not blocked. current, the fault ride-through of the flexible DC converter station is realized by using the fast control response of the flexible DC converter station

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