MMC sub-module topological structure with DC fault blocking capability equivalent to that of full-bridge sub-module

Abstract

The invention discloses an MMC sub-module topological structure with DC fault blocking capability equivalent to that of a full-bridge sub-module. The MMC sub-module topological structure comprises a first output end, a second output end, a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a first voltage stabilizing capacitor and a second voltage stabilizing capacitor, wherein the first voltage stabilizing capacitor, the first transistor, the second transistor, the first diode and the second diode form a first half-bridge sub-module; and the second voltage stabilizing capacitor, the third transistor, the fourth transistor, the third diode and the fourth diode form a second half-bridge sub-module. The structure has the DC fault blocking capacity equal to that of the full-bridge sub-module, caneffectively block fault current when a direct current fault occurs, and is low in cost.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current transmission, and relates to an MMC submodule topology structure of a full bridge submodule equivalent to a direct current fault blocking capability. Background technique [0002] In recent years, flexible direct current transmission technology has become a research hotspot in the field of power transmission. It has a significant role in promoting the development of new technologies such as large-scale wind power grid integration, urban power supply and island power supply, meeting the continuously growing energy demand and promoting clean and efficient utilization of energy. role. At present, there are mainly three types of voltage source converters used in flexible DC transmission projects: two-level voltage source converters, three-level voltage source converters, and modular multilevel converters (MMC). Both two-level and three-level voltage source converters have problems of ...

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Problems solved by technology

The MMC module topology formed by cascading half-bridge sub-modules cannot effectively block DC faults. Once a DC fault occurs, power devices such as transistors and diodes will be burned due to the flow of fault current; full-bridge sub-modules can block DC faults, but the required More transistors, higher cost

At present, many scholars have proposed improved sub-module topologies, most of which have the problem of weak DC fault blocking capability, or require transistors to withstand higher voltages during DC faults, which brings difficulties to the selection of transistors and increases cost of equipment

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