Low-loss modular multilevel converter fault ride-through method

Abstract

The invention provides a low-loss modular multilevel converter fault ride-through method. A converter comprises three phase units, each unit is divided into an upper bridge arm and a lower bridge arm,and each bridge arm comprises a plurality of sub-modules which are connected in series. Each sub-module consists of two half-bridge structures, four capacitors and two fly-wheel diodes, the first half-bridge comprises a first switch module and a second switch module, and the second half-bridge comprises a third switch module and a fourth switch module. The cathode of the first switch module is connected with the anode of the second switch module, the cathode of the second switch module is connected with the anode of the third switch module, and the cathode of the third switch module is connected with the anode of the fourth switch module. By utilizing the properties of the reverse-blocking insulated gate bipolar transistors, when a direct-current side inter-electrode short-circuit fault occurs, a two-way switch composed of the reverse-blocking insulated gate bipolar transistors is turned off, and a fault loop is blocked. According to the method, the fault blocking of direct-current side short circuit can be achieved by controlling the on-off of the switch modules, and meanwhile loss is not increased.

Description

technical field [0001] The invention relates to the technical field of power transmission and distribution in power systems, in particular to a fault ride-through method for a low-loss modular multilevel converter with fault blocking capability. Background technique [0002] With the increase of renewable energy power generation, the integration of renewable energy into the grid has become a very important research direction at present. [0003] The flexible direct current transmission technology provides a solution to solve the grid connection of renewable energy, and has strong technical advantages. Compared with the traditional two-level and three-level converters, the flexible DC transmission technology using modular multi-level converters has better maintainability and scalability, and there is no series voltage equalization and parallel connection of switching tubes. Current sharing problem. Each sub-module of the modular multilevel converter has a relatively simple ...

AI Technical Summary

Problems solved by technology

This additional switching device will increase the conduction loss of the system, resulting in the loss of resources

The existing fault ride-through methods are almost entirely based on the control of the additional switching device, which cannot reduce the conduction loss of the system

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