Preprint Article Version 1 This version is not peer-reviewed

Application of a Hybrid Method for Power System Frequency Estimation with a 0.2-Second Sampled Period

Version 1 : Received: 26 April 2018 / Approved: 26 April 2018 / Online: 26 April 2018 (09:01:07 CEST)

How to cite: Lee, C.; Tsai, M. Application of a Hybrid Method for Power System Frequency Estimation with a 0.2-Second Sampled Period. Preprints 2018, 2018040337 (doi: 10.20944/preprints201804.0337.v1). Lee, C.; Tsai, M. Application of a Hybrid Method for Power System Frequency Estimation with a 0.2-Second Sampled Period. Preprints 2018, 2018040337 (doi: 10.20944/preprints201804.0337.v1).

Abstract

The signal processing technique is one of the principal tools for diagnosing power quality (PQ) issues in electrical power systems. The Discrete Fourier Transform (DFT) is a frequency analysis technique used to process power system signals and identify PQ problems. However, the DFT algorithm may lead to spectral leakage and picket-fence effect problems for asynchronously sampled signals that contain harmonic, inter-harmonic, and flicker components. To resolve this shortcoming, a hybrid method for frequency estimation based on a second-level DFT approach and a frequency-domain interpolation algorithm to obtain the accurate fundamental frequency of a power system is proposed in this paper. This method uses a second-level DFT to compute the cosine and sine parts for the fundamental frequency components of the acquired signals. Then, a frequency-domain interpolation approach is adopted to determine the amplitude ratio for the cosine and sine parts of the system's fundamental frequency. To demonstrate the performance of the proposed frequency estimation method, the observation window used by this paper to evaluate different estimation algorithms is 200 ms. According to the IEC standards, a 200 ms acquisition window is recommended for power system quality assessment. A set of mixed signals with harmonic, inter-harmonic, and flicker components with the fundamental frequency deviation is used. The evaluation results demonstrate the superiority of the new method over other approaches for assessing asynchronously sampled signals contaminated with noise, harmonic, inter-harmonic, and flicker components.

Subject Areas

frequency estimation; asynchronously sampled; harmonic; flicker

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