Localization of nonlinear loads in electric systems through harmonic source estimation

In a liberalized electric market the knowledge of the system status along with uncertainty affecting the estimated data is required to operate management and control issues, such as energy dispatching and protection coordination. The authors have recently proposed a novel procedure for harmonic source estimation aimed at giving distribution network operators information about the possible presence of harmonic producing loads, along with an indication about the reliability of such information. The methodology exploits the few real time measurements existing in distribution systems and all the other available information to realize a first estimation of the harmonic currents injected by the nonlinear loads. In this paper a further headway in this research work is presented. In particular, given that the validity of the results strictly depends on the validity of the input data, great attention has been paid to correctly model, in terms of probability distributions, the a-priori knowledge about the harmonic behavior of the loads. The theoretical fundamentals of the method are discussed and some results relevant to a small distribution network are presented.