MODELLING OF VSC-HVDC LINK

Abstract

With the recent developments in semiconductors and control equipments, Voltage Source Converter (VSC) based High Voltage Direct Current (VSC-HVDC) has become feasible. Due to the use of Pulse Width Modulation (PWM) technique in VSC technology, it has a number of potential advantages such as short circuit current reduction, independent control of the active and reactive power etc. With such very favorable advantages, VSC-HVDC will likely be part of future transmission and distribution systems which supply industrial systems with a high load density, high reliability, quality requirements, and high cost associated with production stoppages. In this thesis, the performance of Voltage Source Converter (VSC) based High Voltage DC (HVDC) transmission system is studied. A 200 MVA, ±100 kV link is modelled between two identical asynchronous AC systems. In addition, a three terminal VSC HVDC system was also studied. The system studies are based on three level neutral point clamped (NPC) converters. Current controlled scheme is used for active, reactive power and dc voltage control. One converter is operated in DC voltage control mode and reactive power control mode, while the other(s) operate in Active and Reactive power (PQ) control mode. The results are carried out in MATLABSIMULINK platform. The results validate the work.