Date of Award

Fall 2018

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical Engineering

Committee Chair

Dan Trudnowski

First Advisor

Josh Wold

Second Advisor

Curtis Link

Third Advisor

Eric Bahr

Abstract

This thesis is composed of two research projects. The first project investigated the feasibility of improving a generator tripping control scheme using wide-area synchrophasors and the second project focused on building a reduced-order model of the western North American power system (wNAPS) for use in a real-time digital simulator.

Transient stability is a major reliability issue for power systems. Radially-connected power plants are especially prone to transient stability problems. An example of this is the fourgenerator Colstrip power plant located in southeast Montana, USA. The Colstrip generators are protected by a tripping control system called the Acceleration Trend Relay (ATR) that is designed to disconnect generators during system disturbances to prevent asynchronous operation and further system instability. Like most transient stability tripping schemes, the ATR relies entirely on local information. However, because transient stability is a wide-area phenomenon determined by the relative synchronism of the system, local information can produce misoperations causing the ATR to false trip. The first part of this thesis studied the feasibility of using wide-area synchrophasors provided by phasor measurement units (PMUs) to improve protection schemes such as the ATR. Transient stability software was used to model the ATR and evaluate the benefits of adding wide-area measurements to the control scheme.

Real-time simulators are effective tools for studying power systems because they can accurately reproduce electromechanical dynamics while allowing for prototype controllers to be physically connected. However, they impose serious limitations on the size of systems that can be modeled. Model order reduction techniques can be used to lower the computational complexity of a system while approximating the dynamics of the original model. The second part of this thesis presents a reduced-order model of the wNAPS termed the “MicroWECC.” The MicroWECC is a further reduction of the MiniWECC model and was designed to have approximate impedance, generation, and modal characteristics. The model was constructed in two positive-sequence transient simulation tools and then modal analysis was performed to compare the MicroWECC to the MiniWECC model. Parameters for electromagnetic transient program (EMTP) models were also suggested.

Comments

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Electrical Engineering

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