Date of Award

5-2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Electrical Engineering

Advisor

Makram, Elham B

Abstract

The NERC August 14th Blackout report brought out by the task force cited 'failure to ensure operation within secure limits' as one of the main reasons. Many of the numerous recommendations focused on the need for better real-time tools for operators and reliability coordinators. In the absence of such tools the operators are limited to operating in conservative secure operating regions established using offline studies. At the same time, with the fast inception of deregulation, the need to ensure a reliable and secure power system has become all the more vital. The success of a competitive market is dependent upon a reliable and secure transmission system at all times. This dissertation investigates ideas for analytical and intelligent techniques to obtain generation dispatches that would be first-swing stable for a certain set of credible contingencies (three-phase faults) with their respective fault clearing times.
In a deregulated environment, fair operation is dependent upon maximum utilization of available resources. Conventionally the maximum utilization has been made possible by use of the optimal power flow where certain objective(s) are maximized/minimized subject to certain constraints through various mathematical programming techniques. Due to the extremely large computation times required to carry out dynamic security assessment of large disturbances, constraints to ensure dynamic stability, more specifically transient stability have been ignored from state of the art optimal power flow routines today. Rather, such limits are established using offline studies. Since, these limits are established from forecasted data, they are kept on the conservative side to ensure that the power system would be transiently stable for a certain set of credible contingencies. One of the major obstacles of including dynamic security assessment subroutines within the optimal power flow method for real-time operations is the heavy computational burden since it requires solution of differential equations. Another is the extremely high analytical and programming complexity involved with inclusion of constraints to ensure that the 'solution of the differential equations is within certain bounds'. This would enhance the already existing state of the art dispatch routines within energy managements systems by allowing operation closer to stability limits.

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