Candidate
Rashid Al-Abri
Title
Voltage Stability Analysis with High Distributed Generation (DG) Penetration
Supervisor
Ehab El-Saadany
Abstract
Interest in Distributed Generation (DG) in power system networks has been growing rapidly. This increase can be explained by factors such as environmental concerns, the restructuring of electricity businesses, and the development of technologies for small-scale power generation. DG units are typically connected so as to work in parallel with the utility grid; however, with the increased penetration level of these units and the advancements in unit’s control techniques, there is a great possibility for these units to be operated in an autonomous mode known as a microgrid. Integrating DG units into distribution systems can have an impact on different practices such as voltage profile, power flow, power quality, stability, reliability, and protection. The impact of the DG units on stability problem can be further classified into three issues: voltage stability, angle stability, and frequency stability. As both angle and frequency stability are not often seen in distribution systems, voltage stability is considered to be the most significant in such systems. In fact, the distribution system in its typical design doesn’t suffer from any stability problems, given that all its active and reactive supplies are guaranteed through the substation. However, the following facts alter this situation:
- With the development of economy, load demands in distribution networks are sharply increasing. Hence, the distribution networks are operating more close to the voltage instability boundaries.
- The integration of distributed generation in distribution system introduces some probability of encountering some active/reactive power mismatches resulting in some stability concerns at the distribution level.
Motivated by these facts, the target of this thesis is to investigate, analyze and enhance the voltage stability of distribution systems with high penetration of distributed generation. In order to accomplish this target, this study is divided into three perspectives: 1) utilize the DG units to improve the voltage stability margin and propose a method to allocate DG units for this purpose, 2) investigate the impact of the DG units on proximity to voltage stability 3) conduct harmonic resonance analysis to visualize the impacts of both parallel and series resonance on the system’s stability. These perspectives will be tackled in Chapter 3, Chapter 4, and Chapter 5 respectively.