Operation Control and Analysis of Hybrid Multiterminal HVDC System Using Different Control Strategies under Abnormal Conditions /

Abstract

HVDC transmission system technologies are becoming more suitable for integration of clean energy sources with improved reliability, security, efficient controllability and desirable stability. It has also been made cost effective for several applications of power transfer usually beyond a certain distance and higher power ratings. Most of the HVDC links being deployed these days are LCCs and VSCs with two level and multi-modular level conversion technologies. The advancements in the interoperability of these technologies with both AC and DC systems has given rise to the application of MTDC systems. Moreover, the pressures from the international communities to decrease greenhouse gases, has forced scientific community all over the globe to bring effective technologies in the market, to replace over the counter carbon di oxide emitting technologies. For the above reasons the focus has also shifted towards using MTDC systems. However this technology is not yet fully matured yet, and requires state of the art research and analysis. Recent research studies have stressed over, developing non Hybrid HVDC grids based on only single type of converter technologies. However, this research work explores the performance of a proposed scenario for integrating different systems using a Hybrid LCC-MMC type MTDC scheme with the use of DC-DC converter. Furthermore, the topological analysis of the scheme, also requires scrutiny during different abnormal conditions to improve the reliability of the grids. The systems startup schemes and performance under specific faulty conditions are also compared using the integration of virtual energy sources and incorporating different HVDC networks with DC-DC converters. The multiple advantages from the in-depth analysis have been highlighted in detail in the thesis ahead.