Series voltage compensators and systems for suppressing commutation failures in conventional dc converter stations

Abstract

The invention discloses a series voltage compensator and a system for inhibiting commutation failure of a conventional DC converter station. The compensator comprises a first to a third converter chain, wherein each converter chain of the first to the third converter chain comprises a plurality of fully controlled voltage source sub-modules and is connected in series with an LCC- Between the HVDCconverter transformer and the AC port of the converter to control the series voltage to assist the valve bank commutation and increase the LCC- The commutation voltage area of the HVDC converter. Thecompensator adopts the converter chain composed of controllable full-bridge submodules connected in series between the converter AC port of conventional DC system and the converter transformer, and does not need to modify the internal structure of the original converter bridge arm, which is conductive to LCC- HVDC has good commutation failure suppression and fast recovery ability, which can significantly improve the performance of LCC The ability of HVDC to resist commutation failure and the recovery speed after commutation failure have the advantages of high control flexibility, low cost andgood engineering practicability.

Description

technical field [0001] The invention relates to the technical field of high-voltage direct current transmission, in particular to a series voltage compensator and a system for suppressing commutation failure of a conventional direct current converter station. Background technique [0002] The traditional grid-commutated high-voltage direct current transmission system (line commutated converter, LCC-HVDC) has the advantages of long-distance large-capacity power transmission and controllable active power, and is widely used around the world. However, since the thyristors used in its converters need to rely on the AC system to provide commutation voltage, commutation failures are prone to occur in the event of AC system failure, resulting in a surge in DC current and a rapid loss of DC transmission power. In addition, in recent years, some regional power grids in my country have had multiple DC feed-ins. Once a commutation failure occurs in a certain DC line, the coupling of th...

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Problems solved by technology

However, due to the need to install additional circuits in each bridge arm of the LCC converter, the utilization rate of the additional components is not high, and it involves the modification of the LCC converter body, which is costly and difficult

[0006] In addition, there are also researches, such as a new type of capacitor-commutated converter based on the anti-parallel thyristor full-bridge sub-module, further based on the full-bridge module composed of bidirectional thyristors connected to

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