Date of Award

Spring 4-26-2016

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science in Electrical Engineering (MSEE)

Department

Electrical and Computer Engineering

Advisor

Mohamad Musavi

Second Committee Member

Paul Lerley

Third Committee Member

Donald Hummels

Abstract

In recent times there has been an increasing interest in renewable energies due to public awareness of the negative effects on the environment of conventional electricity generation resources like coal and oil, and several policies have been enacted requiring progressive reduction of fossil-fuel-based generation. Due to some favorable characteristics of wind over other renewables, wind power has grown considerably in the last two decades.

Integration of wind generation into the existing power grids poses significant challenges. The limited reactive power capability that wind turbines have can cause several problems, such as important voltage drops or rises in the system. Therefore, dynamic voltage stability is a major concern. This thesis presents an investigation of the voltage characteristics of an electric grid connected to wind generation and subject to fault conditions. A comparison between the dynamic voltage performance of synchronous machines, which are the traditional type of generators, and wind farms has been made. Both type III and type IV wind turbines have been considered, as they are the dominant types in the market.

The New England region possesses abundant potential for developing both inland and offshore wind power generation. However, inland wind resources are mostly in remote locations in Northern New England, far from major load centers. Therefore, long transmission lines are required to connect the wind farm to the rest of the power grid, placing them in a weak point of the system. The present study includes an analysis of the role that the point of electrical interconnection of a wind farm with the rest of the system plays on dynamic voltage performance. The Thevenin impedance seen by the wind bus has been used as a measure of the strength of the connection, and its relation with several variables that characterize the severity of a fault has been determined. The concept of Thevenin impedance has not been used in the literature before to study the dynamic voltage response of a wind farm, and it is proved by this work to be a useful tool for assessing the best option when connecting a wind farm to a power grid.

The IEEE standard 39-bus system, which is a simplified representation of the New England electric grid, has been used as a platform to illustrate the developed methodology. The present study has set the base for extending the analysis to the real New England power system.

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