Analysis of Filter Design Approaches for Extraction of Instantaneous Symmetrical Components

Extraction of instantaneous symmetrical components plays a vital role in the operation of grid-connected converters. Conventionally, extraction of instantaneous symmetrical components is achieved by transforming the signal into a rotating reference frame and passing it through a digital filter. This work focuses on the design and performance of various digital filters adopted for the extraction of instantaneous symmetrical components. The design considerations and associated trade-offs involved in the design of digital filters are first outlined. Subsequently, the design procedure involved in commonly adopted filtering strategies is reviewed and their performance under various operating conditions is studied. In addition, this work also analyzes the impact of filter design on closed-loop applications such as phase locked loops.