Abstract：This paper proposes a group of high performance filters for the detection of fundamental symmetrical sequences and harmonics under varied grid conditions based on a basic filter cell. The filter cell is demonstrated to be equivalent to a band-pass filter in the stationary frame,and is easily implemented using a multi-state-variable structure. To achieve high performance in different grid conditions,cascaded filters are developed for distorted and unbalanced grids. This paper also analyzes the robustness of the filter for small frequency variations,and improves its frequency adaptive ability for large frequency changes. Furthermore,it is proved that the filters can also be applied for the synchronization and fundamental-frequency component detection in a single-phase system. The effectiveness of the presented filters is verified by experiments.
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2014, Vol. 29 
