SOME INVESTIGATIONS ON VSC BASED HVDC SYSTEMS

Abstract

This thesis presents work on VSC based HVDC systems. Chapter one presents a review of AC systems and various HVDC systems. It explains about various aspects such as components of HVDC system, various configurations used in HVDC systems. Chapter two consists of a synchronous reference theory based control algorithm for two level VSC based HVDC system. The various techniques used for PWM are also explained. The performance of the two level VSC based system under different two cases is observed. Chapter three discusses control algorithm for three level VSC based HVDC system. The dynamic modelling of VSC is also explained. The modeling and operation of three level diode clamped NPC converter is discussed and the generation of PWM gating pulses for the same is observed. Also, the performance of the two level VSC based system is compared with three level VSC based HVDC system. Chapter four presents fault analysis of three level VSC based HVDC system and results have been presented for single line to ground and three phase fault conditions. Chapter five discusses the modeling and control of multi terminal three level VSC based HVDC systems and their dynamic performance.