Two digital filtering algorithms for fast estimation of symmetrical components in a power system: A static estimation approach

Abstract

This paper presents the application of two digital filters working together for fast estimation of power systems symmetrical components. The three-phase unbalanced system is transformed to two phases using α–β-transformation. Using such a transformation, harmonics of order 3 and their multiples, in the input signal, are suppressed. Having identified the two-phase voltages, the positive and negative sequence phase voltage can be calculated using a constant transformation matrix. The zero sequence component is easily estimated by averaging the unbalanced three-phase voltage at every sample instant. Least error square algorithm is used to identify the magnitude and phase angle of sequence components from the available samples of the specified component.