Line commutated converter structure for anti-parallel thyristor-based full bridge submodule converter

Abstract

The invention provides a line commutated converter structure for anti-parallel thyristor-based full bridge submodules (anti-parallel thyristor-based Full bridge submodules, APT-FBSMs). A topology is that each APT-FBSM is connected between each phase of converter and each phase of converter transformer in series; and each APT-FBSM comprises four groups of anti-parallel thyristors and a capacitor. The topological structure can control the capacitor in each APT-FBSM to provide an auxiliary commutating voltage to a converter valve arm in an AC system failure; the system commutating area is increased; and the commutation failure probability of a traditional line commutated converter is effectively lowered. Due to the flexible controllability of each APT-FBSM, an extra harmonic problem is not caused when an AC system normally works; and the problem that the converter loses the self-recover ability due to the fact that each capacitor is continuously charged to an overvoltage when a commutation failure appears can be avoided.

Description

technical field [0001] The invention relates to the technical field of power transmission and distribution, in particular to a grid commutation converter structure based on an anti-parallel thyristor full-bridge sub-module converter. Background technique [0002] Since the line-commutated converter high voltage direct current (LCC-HVDC) of the power grid uses ordinary thyristors without self-shutoff capability as the commutation components, it can only control the opening of the components, and the switching off of the components depends on the AC current passing through each cycle. achieved at zero. Therefore, the LCC-HVDC system requires a certain strength of the AC system to achieve commutation, which makes the LCC-HVDC objectively have the possibility of commutation failure when the AC system fails and the AC bus voltage drops. [0003] A commutation failure can have a number of very serious consequences. Commutation failure will cause problems such as DC bias of the c...

AI Technical Summary

Problems solved by technology

However, CCC has the following problems: the fault recovery time is significantly longer than that of LCC in the event of an asymmetrical fault; in the event of a commutation fault, the capacitor is continuously charged to overvoltage, and the converter will lose its self-recovery ability; the introduced capacitor causes current harmonics in the DC transmission system wave pollution

Unlike CCC, which puts the capacitor on the valve side of the converter transformer, the controlled series capacitor converter (CSCC) technology is used to put the capacitor on the grid side of the converter transformer, and the capacitance value can be dynamically adjusted, but the essence is different from that of CCC. Similar, the above problems still exist, and it has higher requirements for the following characteristics of the filter device

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