DC side auxiliary commutation hybrid converter topological structure and control method thereof

Abstract

The invention relates to a DC side auxiliary commutation hybrid converter topological structure and a control method thereof. The DC side auxiliary commutation hybrid converter topological structure comprises a three-phase six-bridge-arm circuit and an auxiliary commutation circuit which is connected in parallel with the DC side of the three-phase six-bridge-arm circuit and has forward current controllable turn-off and forward and reverse voltage blocking capabilities. The auxiliary commutation circuit is connected with a connection point of an upper bridge arm and a lower bridge arm of each phase of bridge arm circuit in the three-phase six-bridge-arm circuit through a two-way valve which is arranged on each phase of alternating current bus in a three-phase alternating current bus and hastwo-way opening and two-way voltage withstanding capabilities. According to the DC side auxiliary commutation hybrid converter topological structure and the control method thereof of the invention, the auxiliary commutation circuit connected in parallel with the direct current side of the three-phase six-bridge-arm circuit is additionally arranged in the hybrid converter topological structure, sothat the commutation fault problem of the hybrid converter topological structure can be solved, and the topological structure is simple to implement and low in cost.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a hybrid converter topology structure and a control method for DC side auxiliary commutation. Background technique [0002] The traditional line commutated converter high voltage direct current (LCC-HVDC) transmission system has the advantages of long-distance large-capacity transmission and controllable active power, and is widely used in 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 have had multiple DC feed-ins. Once a certain DC line fails to commutate, the coupling of the AC system may lead to chain commutation failures of multiple DC lines, which will bring a negative impact on th...

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Problems solved by technology

In addition, in the prior art, there is also a device that can be turned off to forcibly turn off the current to realize the transfer of current. However, due to the long-term conduction of the current by the device that can be turned off, this commutation technology increases the operating loss and requires additional cooling. equipment, making the cost of this technical solution higher

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