Power System Dynamic Voltage Management with Advanced STATCOM and Energy Storage System

Abstract

STATCOM (static synchronous compensator) and ESS (energy storage system), as a shunt-link flexible AC transmission system (FACTS) controller, has shown extensive feasibility in terms of cost-effectiveness in a wide range of problem-solving abilities from transmission to distribution levels. Recently, advances in power electronics technologies, such as the emerging kilohertz high power semiconductor switches, cascaded multilevel converter (CMC) topology comprising modular H-bridge voltage source converter (VSC), and digital control technology, have the potential to achieve the modularity and scalability design, lower the overall cost, and improve the reliability and functionality of power electronics-based controllers, hence, resulting in increasing applications of STATCOM⁄ESS. However, how to control a CMC-based STATCOM⁄ESS to realize excellent performance, high reliability and low cost poses the challenges to researchers.

On the other side, renewable large wind farms, as a fast growing power generation method, undergoes its inherent power quality and stability issues. How to develop the effective and accurate model of a wind power system and how to control STATCOM for wind power support are not in a classical textbook and posing challenges. Meanwhile, as an industrial customer of utilities, electrical arc furnace (EAF) is the major flicker source that degrades the grid power quality. How to economically and efficiently mitigate EAF flicker is a tough issue bothering utility professionals. As a promising solution, a high bandwidth STATCOM⁄ESS can be used.

This dissertation is dedicated to a comprehensive study of CMC-based STATCOM and its ultracapacitor energy storage system (UESS), and its applications in power system dynamic voltage management, specifically, wind farm voltage fluctuations suppressions and EAF flicker mitigation. The goal of this dissertation is to achieve high-performance, reliable, flexible, cost-effective controllers of the CMC-based STATCOM⁄UESS for the specific challenging utility applications. Major contributions proposed in this dissertation include:

1) STATCOM model analysis and compensator design guideline;

2) STATCOM AC-side energization and de-energization;

3) STATCOM per-phase DC voltage balancing;

4) wind farm voltage fluctuation suppression;

5) EAF flicker mitigation;

6) modeling, integration and control of UESS.