Inter-cluster voltage balancing control of a delta connected modular multilevel cascaded converter under unbalanced grid voltage

Abstract A new inter-cluster DC capacitor voltage balancing scheme for a delta connected modular multilevel cascaded converter (MMCC)-based static synchronous compensator (STATCOM) is presented. detailed power flow analysis of applying negative sequence current (NSC) and zero-sequence (ZSC) injection methods in addressing the issue imbalance under unbalance grid carried out. control proposed which integrates both using quantification factor Q F . This used to achieve sharing active between NSC ZSC methods. An accurate method determining also The offers better sub-module prevents overcurrent. influence unbalanced on MMCC-based STATCOM rating this integrated cluster technique investigated. verified with 5 kV 1.2MVA MMCC-STATCOM 3-level bridge sub-modules, results show advantages over other