Abstract :
Until now, little attention has been paid to load-flow methods with variables expressed in rectangular form. These methods could have some advantages over existing methods in polar form, bearing in mind the large amount of computation required for load-flow calculations in large networks where evaluation of polar trigonometric functions is necessary. This paper presents several decoupled load-flow methods, some of them having very good convergence and time characteristics, based on the application of Newton´s method to equations of nodal power or current mismatches with the variables, i.e. the nodal voltages, expressed in rectangular form. All the methods presented are compared with several variants of the decoupled load-flow method with variables in polar form. The methods given are applied in studies of electrical networks with different voltage levels from distribution to EHV and various elements, including transformers, cables, short lines, long lines, as well as conditioned and ill-conditioned systems. Comparison is made between all methods by noting the number of iterations for converged solutions from a common start to the end of the iteration process.
