Systematic Errors in the Interpolated-DFT-Based Frequency Estimation for the Control of Power Using Generalized Maximum Sidelobe Decay Windows

The paper presents the analysis of systematic errors of the frequency estimation in a new method based on 3-point interpolated DFT (IpDFT) with the use of Generalized Maximum Sidelobe Decay Windows (GMSD). The source of systematic errors, values of these errors for different parameters of IpDFT and GMSD windows have been analyzed in the paper and practical plots and analytical formula for upper limit of these errors have been derived. It allows a proper application of the 3-point IpDFT method with GMSD windows to obtain high accuracy of the frequency estimation in real time systems, where the systematic errors must be on the level 10-6 or much below this value. The application of the presented method in the control of power grid in renewable energy power systems is indicated as a good solution, especially in small systems, where both high accuracy frequency estimation and low cost are considered to be important conditions.