28-06-2013, 12:53 PM
MODELING AND CONTROL OF A MODULAR MULTILEVEL CONVERTER – BASED HVDC SYSTEM UNDER UNBALANCED GRID CONDITIONS
MODELING AND CONTROL.ppt (Size: 488.5 KB / Downloads: 18)
ABSTRACT
MMC- new topology for HVDC Systems.
Aim- a) analysis and modeling b)develpoment of a control scheme
Generalized mathematical model under unbalanced grid conditions.
Dual current control scheme is applied.
Power controller and zero sequence current controller is provided.
INTRODUCTION
VSC technology is used in HVDC systems.
Compared to ac systems, hvdc is better.
Long distance transmission.
Lower loss.
Limitation of short circuit currents.
Controlling of active power transmitted.
Multilevel approach- reduction in harmonics
Independent control of each modular part.
MMC concept- high capability to improve reliability.
Analysis & modeling of a KW system is done
Block of each SM
Each SM consists of a simpler chopper cell.
Two IGBT switches and two anti parallel diodes.
Each phase leg consists of two arms.
Inductor to compensate voltage difference between upper and lower arms.