Electric power system with remote monitoring and control of protective relays
First Claim
1. In an electric power system including a plurality of analog protective relays having inputs including at least one of the current and voltage in said electric power system at the relays and having as outputs electrical contacts having states representing conditions within said protective relays based upon said inputs, a monitoring and control system comprising:
- a plurality of slave stations each associated with at least one of said analog protective relays and having a slave digital computer with means to store changes in state of said contacts in the at least one associated protective relay and means to generate and store a time tag for each change in state of said contacts, a communications network transmitting said stored changes in state of said contacts and the time tags therefore, and a single master station having a master digital computer programmed to receive the changes in state of said contacts and said tags for each slave station and to store the same.
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Accused Products
Abstract
Monitoring and control of analog electromechanical protective relays and digital mcroprocessor based relays is integrated through a system including slave stations which record and time tag contact activity at each of the analog relays. The slave stations continuously retain digital samples of a predetermined number of the most recent cycles of the currents and voltages at the analog relays and when a trip occurs store the retained samples as pre-fault values together with a preset number of post-fault samples. A master station communicates with the slave stations monitoring the analog relays and with the digital relays through a two way communications network. The master station repetitively polls the slave stations and digital relays for contact activity. Detailed data such as the time tags and pre-fault and post-fault currents and voltages are then requested from those stations reporting contact activity. Either the slave stations or master station calculate fault location and type from the fault voltages and currents, an periodically calculate routine metering parameter such as watts and VARs.
72 Citations
15 Claims
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1. In an electric power system including a plurality of analog protective relays having inputs including at least one of the current and voltage in said electric power system at the relays and having as outputs electrical contacts having states representing conditions within said protective relays based upon said inputs, a monitoring and control system comprising:
a plurality of slave stations each associated with at least one of said analog protective relays and having a slave digital computer with means to store changes in state of said contacts in the at least one associated protective relay and means to generate and store a time tag for each change in state of said contacts, a communications network transmitting said stored changes in state of said contacts and the time tags therefore, and a single master station having a master digital computer programmed to receive the changes in state of said contacts and said tags for each slave station and to store the same. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- 13. In an electric power system including multiple protective relays a plurality of which comprise independent analog protective relays each having inputs including at least one of the current and voltage in said electric power system at the relay and having as outputs electrical contacts having states representing conditions within said analog protective relay including trip conditions based upon said inputs, a monitoring and control system comprising a plurality of slave stations each associated with at least one analog protective relay, each said slave station having a digital computer programmed to store for each associated analog relay changes in state of said electrical contacts including a change in state of a contact indicating a trip condition in said analog protective relay and to store the current and voltage at said analog protective relay at said change in state of said contact indicating a trip condition, a common communications network transmitting for each slave station said stored changes in state of said contacts indicating a trip condition and the stored current and voltage at the change in state for said associated analog protective relays, and a master station having a master digital computer programmed to receive from each slave station said stored change in state of said contacts indicating a trip condition and the stored current and voltage at the change in state transmitted by the communications network, one of sad slave digital computers and said master digital computer being programmed to determine the distance to a fault causing the change in contact state from the current and voltage at the change in contact state, and when said slave digital computers determine said distance to a fault transmitting the distance to the fault over the common communications network to the master station.
Specification