Power grid with comparison of differences in remote phasor changes
First Claim
1. A method for monitoring the stability of a power transmission system at a monitoring location by referencing geographically remote nodes;
- comprising;
(a) taking a first sample of an AC power line parameter at a first node location using a first monitor to produce a first phasor representing the AC power line parameter at the first node,(b) taking a second sample of an AC power line parameter using said first monitor after a first time interval to produce a second phasor representing the AC power line parameter at the first node,(c) calculating from the first and second phasors, the product of one times the complex conjugate of the other, and using the result to produce a phase difference indicator for the first node;
(d) sending the phase difference indicator for the first node to the monitoring location over an electronic network;
(e) taking a third sample of an AC power line parameter at a second node location geographically remote from the first using a second monitor to produce a third phasor representing the AC power line parameter,(f) taking a fourth sample of an AC power line parameter at the second node using said second monitor after a second time interval to produce a fourth phasor representing the AC power line parameter at the first node,(g) calculating from the third and fourth phasors, the product of one times the complex conjugate of the other, and using the result to produce a phase difference indicator for the second node;
(h) sending the phase difference indicator for the second node to the monitoring location over said electronic network; and
(i) calculating a first relative phase change rate indicator using at least a first processor at the monitoring location from the phase difference indicators of the first node and the second node.
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Abstract
The invention compares geographically remote locations on a power grid by determining at each location the amount of change to phasor measurements for a period of time, and then comparing the determined change values from each location to determine relative differences in values as an indicator of the stability of the power grid. One embodiment calculates the product of the node'"'"'s most recent phasor and a complex conjugate of that nodes previous phasor sample to produce a phase difference phasor for that node. The various phase difference phasors are sent to a monitoring location (which may be local for one of the phasors) and comparisons made among the phase difference phasors to assess the amount of load imbalance among the nodes that are being compared.
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Citations
24 Claims
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1. A method for monitoring the stability of a power transmission system at a monitoring location by referencing geographically remote nodes;
- comprising;
(a) taking a first sample of an AC power line parameter at a first node location using a first monitor to produce a first phasor representing the AC power line parameter at the first node, (b) taking a second sample of an AC power line parameter using said first monitor after a first time interval to produce a second phasor representing the AC power line parameter at the first node, (c) calculating from the first and second phasors, the product of one times the complex conjugate of the other, and using the result to produce a phase difference indicator for the first node; (d) sending the phase difference indicator for the first node to the monitoring location over an electronic network; (e) taking a third sample of an AC power line parameter at a second node location geographically remote from the first using a second monitor to produce a third phasor representing the AC power line parameter, (f) taking a fourth sample of an AC power line parameter at the second node using said second monitor after a second time interval to produce a fourth phasor representing the AC power line parameter at the first node, (g) calculating from the third and fourth phasors, the product of one times the complex conjugate of the other, and using the result to produce a phase difference indicator for the second node; (h) sending the phase difference indicator for the second node to the monitoring location over said electronic network; and (i) calculating a first relative phase change rate indicator using at least a first processor at the monitoring location from the phase difference indicators of the first node and the second node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- comprising;
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18. A method for determining at a common monitoring location, useful information about a power transmission system including a power grid, comprising:
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(a) receiving at a first processor a first phase difference indicator corresponding to a first location on the power grid, (b) receiving at said first processor a second phase difference indicator corresponding to a second location on the power grid, remote from the first location, (c) calculating, using said first processor, a first relative phase change rate indicator at the monitoring location from the first and second phase difference indicators received, and (d) using the calculated first relative phase change rate indicator as an indicator of the stability of the power transmission system'"'"'s operation. - View Dependent Claims (19, 20)
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21. A method useful in the monitoring of the stability of a power transmission system comprising:
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(a) taking a first sample of an AC power line parameter using a first monitor to produce a first phasor representing the AC power line parameter; (b) taking a second sample of the same AC power line parameter using said first monitor after a first time interval to produce a second phasor representing the AC power line parameter; (c) calculating from the first and second phasors, the product of one times the complex conjugate of the other, and using the result to produce a phase difference indicator for the first node; (d) transmitting to a remote location over an electronic network the phase difference indicator for the first node; and (e) repeating the prior steps sufficiently frequently to allow for use of the transmitted indicators in monitoring of the stability of the power transmission system over time. - View Dependent Claims (22, 23, 24)
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Specification