Stability and transient-behavioural assessment of power-electronics based dc-distribution systems. Part 3: Application of Kharitonov polynomials

Abstract

Ideas and developments in electrical systems are being stimulated by progress in power electronics; nowhere is this more apparent than in the marine industry. Indeed, it may be that such advances will lead to dc-distribution systems appearing once again in vessels. Concomitant with these developments is the need for new methods, or adaptation of known methods, to be found to deal with the design and analysis problems that will inevitably arise.The problem considered in this paper is an extension of that considered in Part 11,2 and Part 23 of this series of papers. That is, a dc-supply feeding a constant-power load. This arrangement is one that is susceptible to stability problems. Work on this problem, using the Nyquist criterion-based method has been reported1 and, more recently, using the root-locus technique2 and Bode and Nyquist frequency domain techniques.3 This paper is concerned with the effect on system stability of variation in circuit parameters from design values and applies the Kharitonov polynomials to establish comprehensive design assessments of system stability when there are deviations in several of the circuit parameters, as inevitably there will be.