Power systems modeling using fuzzy logic

Modeling of electrical networks elements (electric lines and transformers) during steady state operation is based on the following suppositions: a) supply voltage system is balanced; b) currents are sinusoidal and form a balanced system of phasors; c) network parameters are constant; d) running state is permanent and stationary. These hypotheses can be correctly applied for single-phase and positive sequence schemes. An accurate modeling of electrical networks supposes the consideration of power losses and non-linear and unbalanced loads, which cause a distorted unbalanced operation state of the distribution and transmission networks. Therefore, the electric lines and transformers models have to be made taking into account the skin and proximity effects, the hysteresis phenomenon, losses due to inrush currents in magnetic materials etc. Paper presents a method to estimate parameters of electric lines and transformers using fuzzy logic. The electric parameters are considered fuzzy number, hence the input linguistic variables, fuzzyfication and defuzzyfication methods, knowledge base and output variables are presented. A virtual instrument that was created to evaluate parameter values is also presented.