Stability and transient-behavioural assessment of power-electronics-based dc-distribution systems

Abstract

Power-electronic systems are becoming increasingly important in marine engineering applications. Power electronics is stimulating new concepts and developments in electrical machines and distribution systems.Concomitant with such developments is usually a need for new methods for analysis and design activities. An increasingly serious contender for a power distribution system is a dc one. Such systems are well-known in satellite engineering. Inevitably they will become more important as fuel-cells become common in marine use. One problem with dcbased systems is that they are susceptible to instability, particularly when a constantpower regime is operating. Work on examining this problem is described by Sudhoff et al11 using a method based on the Nyquist stability criterion.The purpose of this paper is to demonstrate that an approach to this problem, based on the root-locus technique, is well worth considering. Not only does this technique produce indications of when to expect instability, but it also indicates the type of behaviour to be expected at any operating point.In this way it provides a simple means of assessing transient behaviour as the values of certain key components are altered. The efficacy of the technique is demonstrated by using a problem originally analysed in Sudhoff et al.