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 controlling electric power through a switch in a power network, the system comprising:
- a switch configured to allow or interrupt current flow on a power line;
- voltage and current sensors configured to measure voltage and current on the power line;
- an analog-to-digital converter configured to convert the measured voltage and current to digital samples;
- a phasor measurement unit (PMU) comprising:
- a processor configured to:
- calculate phasors having a phase angle and magnitude from the digital samples using at least one discrete Fourier transform (DFT) algorithm;
- estimate a frequency of the phasors using a plurality of spaced-apart, non-consecutive phasors;
- calculate a rate of change of frequency (RoCoF) from the estimated frequency;
- and generate a control signal for the switch based on the estimated frequency and RoCoF.
A method for controlling electric power through a switch in a power network, the method comprising:
- measuring voltage and current on a power line using voltage and current sensors;
- converting the measured voltage and current to digital samples using an analog-to-digital converter;
- calculating phasors having a phase angle and magnitude from the digital samples using at least one discrete Fourier transform (DFT) algorithm;
- estimating a frequency of the phasors using a plurality of spaced-apart, non-consecutive phasors;
- calculating a rate of change of frequency (RoCoF) from the estimated frequency;
- and generating a control signal for the switch based on the estimated frequency and RoCoF.
Dependencies are inferred from the claim text.