PROTECTIVE RELAY WITH SYNCHRONIZED PHASOR MEASUREMENT CAPABILITY FOR USE IN ELECTRIC POWER SYSTEMS
First Claim
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1. A protective relay for electric power systems for system-wide control and analysis and for protection, comprising:
- acquisition circuits for obtaining at least one of the following;
(1) voltage values and (2) current values from a power line;
a first sampling circuit for sampling said voltage and/or current values at selected intervals of time;
a first calculation system using the resulting samples to perform selected power system-wide control and analysis determinations;
a frequency estimating circuit for determining the power system frequency;
a second sampling circuit for resampling the sampled voltage and/or current values at a rate which is related to the power system frequency; and
a second calculation system using the resampled voltage and current values to perform selected protection functions for the portion of the power line associated with the protective relay.
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Abstract
The relay system obtains voltage and current values from a power line and uses a first sampling element to sample the voltage and current values at selected intervals of time. The resulting sampled signals are used for power system-wide protection, control, monitoring and metering. The sampled signals are then resampled at a rate which is a selected multiple of the power system frequency. The results of the resampling are used by processing circuitry for protection functions including fault determinations.
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Citations
15 Claims
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1. A protective relay for electric power systems for system-wide control and analysis and for protection, comprising:
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acquisition circuits for obtaining at least one of the following;
(1) voltage values and (2) current values from a power line;
a first sampling circuit for sampling said voltage and/or current values at selected intervals of time;
a first calculation system using the resulting samples to perform selected power system-wide control and analysis determinations;
a frequency estimating circuit for determining the power system frequency;
a second sampling circuit for resampling the sampled voltage and/or current values at a rate which is related to the power system frequency; and
a second calculation system using the resampled voltage and current values to perform selected protection functions for the portion of the power line associated with the protective relay. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 15)
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11. A protective relay for electric power systems using synchronized phasor measurements for system-wide control and analysis and for power line protection, comprising:
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voltage and current acquisition circuits for obtaining voltage and current values from a power line;
a sampling circuit for sampling the voltage and current values at selected intervals of time, wherein the sampling is based on an absolute time value reference;
a first calculation system using the sampled signals to perform selected power system-wide protection, control and analysis determinations and for producing synchronized voltage and current phasor values from the acquired voltage and current values, the synchronized voltage and current values being substantially independent of system frequency for protection and control functions; and
a second calculation system responsive to synchronized phasor values from the said protective relay and from another relay which is remote from said protective relay on the same power line. - View Dependent Claims (12, 13, 14)
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Specification