EMTP, transient stability and power flow models and controls of VSC based FACTS controllers

Abstract

This thesis gives an overview of the emerging FACTS technology with emphasis on the STATCOM, SSSC and UPFC controllers. The basic operating principles of the controllers are explained in this thesis together with the man circuit configurations, functions and general control strategies. The thesis proposes and describes transient stability and power flow models of the STATCOM, SSSC and UPFC. The proposed models accurately represents behavior of the controllers in quasi steady state operating conditions, and are adequate for transient and steady state analyses of power systems. The models are validated with the help of the Electromagnetic Transient Program (EMTP), where detailed models of the controllers are implemented and compared to the suggested stability models. Also a comparison of different control strategies for the UPFC is given, together with a novel, efficient and simple controls for this controller. A realistic 11-bus power system is used throughout the thesis to validate proposed models and compare different control strategies. The controllers are simulated under different operating conditions using both, the detailed and "reduced", models.