Acquiring phasors outside the frequency tracking range for power protective relays
First Claim
1. A method for obtaining a phasor of a signal waveform, comprising:
- tracking a frequency of the signal waveform;
sampling the signal waveform at a sampling rate;
adjusting the sampling rate to correspond to the frequency of the signal waveform when the frequency is within a predetermined range of frequencies to provide data samples;
calculating a phasor using the data samples; and
,correcting the phasor when the frequency of the signal waveform is outside of the predetermined range of frequencies.
2 Assignments
0 Petitions
Accused Products
Abstract
A system and method for acquiring phasors outside of the frequency tracking range for power protective relays. As the frequency of a power system varies from the rated frequency, phasors calculated from such samples include errors. A frequency tracking range is used to sample the signal waveform at a rate corresponding to the frequency when the frequency is within the frequency tracking range. When the frequency is outside of the frequency tracking range, the signal waveform is sampled at a rate corresponding with the maximum or minimum of the frequency tracking range depending on whether the frequency exceeds or falls below the frequency tracking range. The difference between the frequency and the minimum or maximum of the frequency tracking range is used to correct the measured phasors to result in accurate phasors.
36 Citations
24 Claims
-
1. A method for obtaining a phasor of a signal waveform, comprising:
-
tracking a frequency of the signal waveform; sampling the signal waveform at a sampling rate; adjusting the sampling rate to correspond to the frequency of the signal waveform when the frequency is within a predetermined range of frequencies to provide data samples; calculating a phasor using the data samples; and
,correcting the phasor when the frequency of the signal waveform is outside of the predetermined range of frequencies. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A system for determining accurate fundamental phasors of a signal waveform oscillating at a frequency, comprising:
-
a frequency estimation module for calculating a frequency of the signal waveform a sampling module in communication with the frequency estimation module for sampling the signal waveform at a sampling rate and adjusting the sampling rate to correspond to the frequency when the frequency is within a predetermined range; a phasor calculation module system in communication with the sampling module for determining a measured phasor representing the signal waveform, the measured phasor including a real part and an imaginary part; and
,a phasor correction module in communication with the frequency estimation module and the phasor calculation module, and using a plurality of compensating factors for correcting the measured phasor when the frequency is outside of the predetermined range. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A method for determining accurate fundamental phasors of a signal waveform over a range of frequencies of the waveform, comprising:
-
tracking a frequency of the signal waveform; sampling the signal waveform at a sampling rate; adjusting the sampling rate to correspond to the frequency when the frequency is within a predetermined range of actual frequencies; determining a measured phasor representing the signal waveform, the measured phasor including a real part and an imaginary part; and
,correcting the measured phasor when the frequency exceeds the predetermined range. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
-
Specification