FAST IDENTIFICATION OF SYMMETRICAL COMPONENTS BY USE OF A STATE OBSERVER

The paper presents the synthesis of a state observer which can be appl ied to estimation of the current and voltage symmetrical components in a three-phase electrical network. The state observer algorithm is bas ed on the recursive model of the current and voltage generation proces s in a three-phase power system in which the orthogonal phasors are us ed as the model state variables. The synthesis of state observer is sh own under the assumption that the higher harmonics as well as the deca ying DC offset may be present in the symmetrical component phasors. Th e state observer presented can be used as the fast current and voltage symmetrical component estimator in digital power protection systems. The calculation example included shows the basic properties of the obs erver in such an application.