New scaling concept in power system analysis

Three standard methods which are usually applied for scaling of AC power system models are analysed in the paper: the PU method, the percentage method (P% method) and the SU method (scaling to a unique voltage level). Several theoretical and practical problems of these methods are identified: 1) the PU method is not in full accordance with both formalisms and terminology inherent to distribution practice; 2) applications of both the P% and SU methods are not suitable for elaboration of power system issues; and 3) application of the PU method is not suitable for calculation of the most complex power system (quasi) steady states treated in the sequence domain. These shortcomings are sufficient reason for redefining the standard scaling methods. The redefinition is performed in two steps: 1) standard scaling methods are extended, redefined and synthesised by a new (generalised) scaling concept; and 2) this concept is generalised for elaboration of power system models in the sequence domain. The above mentioned three problems are solved by the new scaling concept. This concept is demonstrated by several representative examples