PROJECT TITLE :

Control Strategy for Modular Multilevel Converters with Redundant Sub-modules Using Energy Reallocation - 2017

ABSTRACT:

By analyzing the topology and mathematical model of modular multilevel converters (MMCs), a management scheme based on the energy reallocation is proposed to control the MMC with redundant submodules. This control scheme is not solely acceptable for the MMC in traditional state however also applicable to the MMC in submodules fault state. Considering the circulating currents characteristics of the MMC in submodule fault state, a part energy controller using proportional integral resonance control is presented, and the circulating currents can be suppressed. As the power loss of the MMCs is closely related to switching frequency of the IGBTs, a replacement modulation strategy primarily based on arm current feedback is proposed in this paper, and this strategy considers not solely the switching frequency's impact however conjointly the collector current's impact on the switching losses. Taking the grid-connected MMC rectifier for instance, the effectiveness of the great management theme and therefore the new modulation strategy are verified by simulations and experiments on a MMC prototype.