Abstract: Abstract:The basic principle of the modularized multilevel converter was introduced, and its mathematic model was deduced. Aiming at the application of the modularized multilevel converter in the static reactive power compensation device with mediumhigh voltage level, an algorithm of nearest level modulation and voltage sharing strategy of submodule based on bridge arm current direction were put forward. Aiming at the close coupling and nonlinear characteristics of the static reactive power compensation device, the dq feedforward decoupling method was adopted to realize the reactive power and DC voltage decoupling control. A detail simulation model with 71 levels was established on PSCAD/EMTDC software platform, and the effectiveness of the modulation and control strategy was verified by the simulation result.

Key words: Keywords:modularized multilevel converter, static reactive power compensation device, dq decoupling control, voltagesharing control