Abstract: Harmonic and interharmonic estimation is essential for Power System monitoring, particularly for Power Quality (PQ) analysis. These components can interfere with the device functionality, leading to motor heating and energy consumption inefficiency. Usually, the estimation of these components is performed by Fourier Transform; however, the estimation accuracy can decrease in specific scenarios. If the sampled signal is asynchronous or is composed of interharmonics, for example, the energy is spread along the frequency spectrum, causing estimation errors. In this context, this work proposes an innovative method to estimate the harmonic and interharmonic, combining a re-sampling method, based on B-spline with a pre-filter, and Interpolated Discrete Fourier Transform (IpDFT) to avoid the leakage caused by asynchronous sampling and interharmonics. Three real-time re-sampling methods combined with IpDFT are analyzed via simulated voltage signals. The results show that the proposed method is accurate, and robust for all scenarios Ver menos