Publication Detail

Composite System Stability Methods Applied to Advanced Shipboard Electric Power Systems

John Victor Amy, Jr.
219 pp.

Large increases in the complexity of shipboard electric loads as well as development of electric drive, integrated electric drive and pulsed power systems make manifest the present and future importance of naval electric power systems. The most crucial attribute of these systems is their ability to fulfill their function in the presence of "large-signal" perturbations. Fundamental differences between shipboard and commercial electric power system''s make all but the most general nonlinear, "large-signal" stability analyses
inappropriate for the design and assessment of naval electric power systems. The tightly
coupled and compact nature of shipboard systems are best accommodated by composite
system stability analyses.

Composite system methods, based upon Lyapunov's direct method, require that each
component's stability be represented by a Lyapunov function. A new Lyapunov function
which is based upon coenergy is developed for 3-phase synchronous machines. This use of coenergy is generalizable to all electromechanical energy conversion devices. The coenergy-based Lyapunov function is implemented as a "stability organ" which generates waveforms at information terminals of a "device object" in the object oriented simulation environment of WAVESIM. Single generator simulation results are used to acquire a
measure of the "over sufficiency" of the coenergy-based L'yapunov function.

Some means of combinulg the components' Lyapunov fullctions is necessary with
composite system stability criterions. To provide tile largest stability re,sion in a Lyapunov
function convective derivative space, thereby reducing Hover sufficlency", a "titllevariant
weighted-sum" composite systcln criteriol1 is developed. This criterion is
inlplemented as a "stability denlon" "device objecttl within the WAVESITvi ellvirollllleKlt.
TIle "stability demon" is tested tllfougl1 RLC circuit simulations alld a two-generator Sitllulation.
The output of the "stability delnon" is suitable for use witlliJl illl overall syst.enl
stabilising controller.

type: Full theses / dissertations

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