Power system transient stability using the critical energy of individual machines

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Vittal, Vijay
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Electrical and Computer Engineering

The Department of Electrical and Computer Engineering (ECpE) contains two focuses. The focus on Electrical Engineering teaches students in the fields of control systems, electromagnetics and non-destructive evaluation, microelectronics, electric power & energy systems, and the like. The Computer Engineering focus teaches in the fields of software systems, embedded systems, networking, information security, computer architecture, etc.

The Department of Electrical Engineering was formed in 1909 from the division of the Department of Physics and Electrical Engineering. In 1985 its name changed to Department of Electrical Engineering and Computer Engineering. In 1995 it became the Department of Electrical and Computer Engineering.

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  • Department of Electrical Engineering (1909-1985)
  • Department of Electrical Engineering and Computer Engineering (1985-1995)

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Recent efforts to apply direct methods of transient stability analysis to multi-machine power systems have used the so-called "energy functions." These functions describe the system transient energy causing the synchronous generators to depart from the initial equilibrium state, and the power network's ability to absorb this energy so that the synchronous machines may reach a new post-disturbance equilibrium state. In spite of the recent successes it has become increasingly evident that system separation depends not on the total system energy, but rather on the energy of the individual machines or groups of machines tending to separate from the rest. Thus, there is a need for generating transient energy functions for individual machines (or for groups of machines);Using a center of inertia frame of reference, the energy function V(,i) for machine i is derived. V(,i) is composed of kinetic energy and potential energy components. It is shown that the critical value of V(,i) is given by the maximum value of its potential energy component and that this value is fairly constant for any unstable post-fault trajectory. A special computer program has been written to compute the critical value of V(,i) for sustained fault conditions;A procedure for first swing transient stability assessment has been developed using the energy function of individual machines and groups of machines. The method has been tested extensively on two power networks: a 17-generator, 163-bus system which is a reduced version of the network of the state of Iowa; and the IEEE 20-generator, 118-bus system;A theoretical justification for using the critical energy of individual machines in stability assessment is provided using the concept of partial stability. Power system transient stability is analyzed as a partial stability problem with respect to the critical group of machines. It is shown that the transient energy function for the critical group of machines satisfies conditions for partial asymptotic stability.

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Fri Jan 01 00:00:00 UTC 1982