L-index based contingency filtering for voltage stability constrained reactive power planning

Abstract

One of the most important objectives in reactive power planning (RPP) is maintaining required voltagestability margin under normal and single-contingency situations. For this, an optimization problem must be formulatedconsidering N-1 contingencies constrained for a set of predetermined contingencies. Traditionally, all these contingenciesmust simultaneously be addressed in the optimization problem. This can dramatically increase the problem dimensionand decrease the convergence ability of its solution for large scale applications. This paper uses an L-index basedcontingency filtering strategy to select a small number of contingencies to be addressed in RPP problem. For this, thepredetermined set of all contingencies is divided into some subsets wherein each subset of contingencies affects an especialpart of power system. Then, only the worst contingency from each subset is selected and addressed in RPP problem sothat the allocated VAr sources can cover all of contingencies. This method reduces the problem dimension and improvesconvergence ability of its solution for large scale applications, whilst the obtained results are similar to the ones takenfrom enumeration method of N-1 contingencies. The implemented simulations on the IEEE 39 and 118-bus test systemsverify the capability of the proposed method.