Modular Multilevel Converter Modeling, Analysis and Control of Short-Circuit Current

this paper introduces a three-phase modular multilevel converter structure and its dynamic behavior during load variations. This converter has been used to feed a three-phase balanced load from a DC power supply, as this load changes in a specified time interval and becomes an unbalanced load. The output current control model is designed such that with load variations, the input DC voltage changes so that the load current is always balanced and sinusoidal. A short circuit happens in one phase of three-phase load and its current is unbalanced. In the control model presented in this paper, the energy stored in the capacitors of upper and lower arms is measured and based on the reference current for the converter, the output voltage changes so that the load current remains also balanced and sinusoidal after fault. The simulation results and closed-loop control model is presented in PLECS.

Keywords:

component , dynamics of load , capacitors energy control , closed-loop control , modular multilevel converter