Adjusted reactive solutions for multiple power flow computations

Abstract

Purpose – The purpose of this work is that of showing some efficient techniques to perform PV-PQ node type switching in multiple power flow computations. Design/methodology/approach – Reactive generation limits of generation buses must be taken into account to obtain realistic power flow solutions. This may result computationally demanding when many power flow computations are required as in contingency screening or Monte Carlo simulations. In the present paper, the implementation of efficient PV-PQ node type switching is examined with particular emphasis on the efficiency of computation. Some different methods are proposed and compared on the basis of computation speed and accuracy. Findings – Tests show the efficiency of the proposed methods with reference to actual networks with up to 800 buses. Originality/value – The classical method of (partial) re-factorisation is not very efficient when many power flow solutions are to be evaluated. In the present work, a different approach is proposed; it is based on grounding each PV node by a fictitious short-circuit branch which is removed when the node type is changed to PQ. This operation is carried out by compensation of the solution and combined with the modifications required for contingency simulation.