Type of Document Master's Thesis Author Zhang, Xuan URN etd-01202004-163949 Title High Precision Dynamic Power System Frequency Estimation Algorithm Based on Phasor Approach Degree Master of Science Department Electrical and Computer Engineering Advisory Committee

Advisor Name Title Liu, Yilu Committee Chair Bostian, Charles W. Committee Member Centeno, Virgilio A. Committee Member Keywords

- phase-shift
- moving averaging
- averaging
- DFT
Date of Defense 2004-01-16 Availability unrestricted AbstractAn internet-based, real-time, Global Positioning System (GPS) ---synchronized relative to the wide-area frequency-monitoring network (FNET) ---has been developed at Virginia Tech. In this FNET system, an algorithm that employs the relationship between phasor angles and deviated frequency [13] is used to calculate both frequency and its rate of change. Tests of the algorithm disclose that, for non-pure sinusoidal input (as compared to pure sinusoidal input), significant errors in the output frequency will result. Three approaches for increasing the accuracy of the output frequency were compared. The first---increasing the number of samples per cycle N---proved ineffective. The second---using the average of the first estimated frequencies rather than the instant first estimated frequency as the resampling frequency---produces a moderate increase in accuracy of the frequency estimation. The third---multiple resampling---significantly increased accuracy. But both the second and the third become ineffective to the extent the input is not pure sinusoidal.From a practical standpoint, attention needs to be paid toward eliminating noise in the input data from the power grid so as to make it more purely sinusoidal. Therefore, it will be worthwhile to test more sophisticated digital filters for processing the input data before feeding it to the algorithm.

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