Modeling and Simulation of a Positive and Negative Sequence Component Separation for Grid Voltage Based on the Improved Method of Instantaneous Symmetrical Components

In this paper, the voltage sag information extraction is taken as the research object, and a simulation model based on voltage sag caused by different transmission lines is established. On account of the problems that the detection techniques of fundamental harmonic of a positive and negative sequence for common grid voltage of power network have poor ability of suppressing harmonic interference and slow detection speed, a method of instantaneous symmetrical component based on adaptive notch filter is proposed. Three adaptive notch filters are used to extract the fundamental components and their 90° phase-shift components of the three-phase unbalanced voltage signal, and the instantaneous symmetrical components are used to separate the fundamental positive and negative sequence voltages of these components. The improved method are simulated. The results of simulation demonstrate that the proposed and improved algorithm can quickly and accurately detect the magnitude of voltage positive and negative sequence components and track the change of grid frequency.