Pmu algorithm
AssigneeS&C Electric Company
InventorsMichael Quinlan, Yoav Sharon
Life of this patent
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Abstract
A system and method for generating phasors having a phase angle and magnitude from a sinusoidal power signal, and using the phasors to generate a frequency and RoCoF of the power signal. The system and method provide improvements over known systems and methods by correcting the frequency of sensor signals, providing a simplified phasor correction equation, reducing errors in a non-recursive DFT algorithm, improving frequency estimation by spacing out DFTs, correcting the sampling rate, providing linear interpolation of frequency and/or providing a variable DFT window length.
Claims20
A system for calculating phasors from a power signal and calculating a frequency and rate of change of frequency (RoCoF) from the phasors, the system comprising:
- a computer including at least one processor and a memory device storing data and executable code that, when executed, causes the at least one processor to:
- measure the voltage and current of the power signal;
- convert the measured voltage and current to a series of digital samples;
- calculate a phasor having a phase angle and a magnitude by operating two recursive discrete Fourier transform (DFTs) algorithms in parallel, where one DFT algorithm is reset while the other DFT algorithm produces data;
- calculate a frequency estimation of the phasor;
- correct the phasor using the frequency estimation;
- filter the frequency estimation;
- and
- calculate the RoCoF from the filtered frequency estimation.
A system for calculating phasors from a power signal and calculating a frequency and rate of change of frequency (RoCoF) from the phasors, the system comprising:
- a computer including at least one processor and a memory device storing data and executable code that, when executed, causes the at least one processor to:
- measure the voltage and current of the power signal;
- convert the measured voltage and current to a series of digital samples;
- calculate a phasor having a phase angle and a magnitude by operating at least one discrete Fourier transform (DFTs);
- calculate a frequency estimation of the phasor;
- correct the phasor using the frequency estimation;
- filter the frequency including performing linear interpolation on a sample window that allows for the frequency estimation to be reported at any point in the sample window;
- and
- calculate the RoCoF from the filtered frequency estimation.
Dependencies are inferred from the claim text.