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arXiv · 2603.05746

Frequency Response of Windowed DFT Phasor Estimation: Impact on Oscillation Observability

Jiahui Yang·Yuru Wu·Haozong Wang·Yu Liu·Biao Sun·Yilu Liu·Clifton Black
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Abstract

Phasor measurement units (PMUs) are widely used for sub-synchronous oscillation monitoring, yet the effect of windowed discrete Fourier transform (DFT)-based phasor estimation on oscillation observability is not fully characterized. This letter derives the complete complex-valued frequency response of the windowed DFT phasor estimator under both magnitude and phase modulation. The analysis shows that the estimation window introduces both frequency-dependent magnitude attenuation and phase shift to oscillation components, governed by the complex gain. A simple recovery method is also proposed to restore the true oscillation amplitude and phase from PMU data using the analytically known complex gain. The results are validated through time-domain simulations and provide guidance for industry practitioners on interpreting PMU-based oscillation measurements and selecting appropriate window lengths.

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Jiahui Yang, Yuru Wu, Haozong Wang, Yu Liu, Biao Sun, Yilu Liu, Clifton Black. 2026-03-05. Frequency Response of Windowed DFT Phasor Estimation: Impact on Oscillation Observability. https://arxiv.org/abs/2603.05746

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