PROJECT TITLE :

Analysis and fault control of hybrid modular multilevel converter with integrated Battery energy storage system (HMMC-BESS) - 2017

ABSTRACT:

A modular multilevel converter (MMC) integrated with split battery modules has been verified a better choice for the large-scale battery energy storage system (BESS). During this case, both ac grid and dc grid can exchange power with the BESS while the power transfer between ac and dc grids will be decoupled. However, while not the ability to ride through dc grid fault, the performance and reliability of whole system will be reduced. Thus, a hybrid MMC (HMMC) with integrated BESS (HMMC-BESS) is proposed during this paper. Then the batteries can exchange power with the normal grid continuously and independently, even when short-circuit fault condition happens on ac or dc grid. However, the ancient management schemes are not suitable for the fault modes. During this paper, the configuration, modeling, and operation modes of HMMC-BESS are discussed 1st. When that, both ac and dc grid fault modes of HMMC are analyzed and control schemes of corresponding mode are presented. As well, novel balancing ways for the state-of-charge and voltage allocation theme are proposed consistent with totally different operation modes. Finally, a downscaled prototype is made in laboratory to verify the proposed management scheme.