A General-Purpose Version of the Fast Decoupled Loadflow

Abstract

A new version of the fast decoupled load flow, in which a more broad range of power systems can be solved, is presented. The key lies in the different way in which the resistances are ignored and in a different iteration scheme. In the standard algorithm the resistances are ignored while building the B' load flow matrix: it is shown that it is preferable that the resistances are ignored in the B matrix instead of the B' matrix. For normal test systems there is hardly any difference in the number of iterations. However, the new algorithm iterates faster if one or more problematic R/X ratios are present. An iteration scheme with strict successive P and Q iterations prevents cycling convergence behavior which can be found in some low voltage systems. The advantages of the new version are demonstrated with runs on IEEE test systems, with both uniformly and nonuniformly scaled reactances. R-scaling up to 3 is always possible, and sometimes values up to 5 can be used. X-scaling of at least 0.1 is possible without losing convergence and with iteration counts which are significantly lower than with the standard scheme. >

Keywords

Affiliated Institutions

• Delft University of Technology NL

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