Study on multilevel converters for static synchronous compensators with energy storage

This dissertation presents the analysis, comparison and implementation of multilevel power electronic converters for static synchronous compensators (StatComs) with energy storage systems (ESS). There are several main contributions made to the study of multilevel converters for flexible AC transmission system (FACTS) devices.; The first contribution is the analysis of several typical existing multilevel converter topologies for the application of StatCom/ESS. The topologies and control methods of these converters are studied and compared, and a 5-level cascaded converter was chosen for its modularity and number of components.; The second contribution of this research is the development of control for a multilevel StatCom with battery energy storage (BESS) for active and reactive power exchange with a small power systems. In addition to the decoupled PI control for active and reactive power (PQ, a new PQ control based on a large signal model was developed and applied to the StatCom/BESS. Various simulation cases in PSCAD were designed and conducted to support the concept of integrating a multilevel converter into a StatCom/BESS.; The third contribution of this project is the development of a laboratory-scale prototype for validation. A three-phase, 5-level cascaded converter was built with Fuji IGBTs and IGBT driving boards were designed to trigger switches. The digital controller contains two DSP boards hosted in a PC and a signal interface board to interface DSPs with driving and sensor electronics. The experiments performed on this prototype verify the model and control, and demonstrate that multilevel converters provide a more advantageous and feasible way to implement StatCom/ESS.