Load restoration in a high or medium voltage substation
The present invention is concerned with simplified configuration as well as supervision and testing of load restoration functions in high or medium voltage substations of electrical power transmission or distribution networks. The invention takes advantage of the fact that all information for load restoration is available from a standardized configuration representation and from dynamically observable events. Specifically, the IEC 61850 Substation Configuration Description (SCD) file includes the substation single line, the bus bar or breaker failure protection functionality related to it, and the way how reclosing commands can be conveyed for the restoration process. A load restore function or load transfer application observes the execution of a protection trip function and the concurrent connection state of the bays to bus bars in order to automatically restore the power flow across a failed bus bar segment to a parallel healthy bus bar segment.
1. A load restoration method in a substation with a bus bar connectable to a plurality of bays and loads, comprising:
reading a standardized configuration description of a substation automation system and obtaining therefrom a static topology representative of at least a part of the substation,
observing a switch status of a switching device of the substation,
establishing a dynamic substation topology upon observation of a status change of the switch status,
observing a trip isolating a segment of the bus bar,
identifying an orphan bay previously connected to the isolated bus bar segment,
identifying connecting switching devices between the orphan bay and an un-tripped bus bar segment, and
issuing close commands on behalf of the connecting switching devices to connect the orphan bay to the un-tripped bus bar segment.
2. The method according to claim 1 , comprising
establishing, based on the dynamic substation topology, for each bay a connecting node to which the bay is connected, and
identifying an orphan bay with a connecting node being part of the isolated bus bar segment.
3. The method according to claim 1 , comprising
establishing, based on the dynamic substation topology, protection zones for the bus bar, and establishing, for each bay a connecting protection zone to which the bay is connected, and
identifying the orphan bay with a connecting protection zone related to the isolated bus bar segment.
4. The method according to claim 1 , comprising, between the steps of observing the trip and identifying the orphan bay, the step of waiting for a delay time of at least 0.5 seconds.
5. The method of claim 1 , wherein the un-tripped bus bar segment is different from the isolated segment of the bus bar.
6. The method of claim 1 , further comprising
issuing an open command to a disconnector in the isolated bus bar segment to connect the orphan bay to the un-tripped bus bar segment.
7. The method of claim 6 , further comprising
issuing a close command to a bay circuit breaker of the orphan bay to connect the orphan bay to the un-tripped bus bar segment.
8. An apparatus comprising an Intelligent Electronic Device IED in a substation with a bus bar connectable to a plurality of bays and loads, the IED configured to:
read a standardized configuration description of a substation automation system and obtain therefrom a static topology representative of at least a part of the substation;
observe a switch status of a switching device of the substation;
establish a dynamic substation topology upon observation of a status change of the switch status;
observe a trip isolating a segment of the bus bar;
identify an orphan bay previously connected to the isolated bus bar segment;
identify connecting switching devices between the orphan bay and an un-tripped bus bar segment, and
issue close commands on behalf of the connecting switching devices to connect the orphan bay to the un-tripped bus bar segment.
9. The apparatus of claim 8 , wherein the IED is further configured to:
establish, based on the dynamic substation topology, for each bay a connecting node to which the bay is connected; and
identify an orphan bay with a connecting node being part of the isolated bus bar segment.
10. The apparatus of claim 8 , wherein the IED is further configured to:
establish, based on the dynamic substation topology, protection zones for the bus bar;
establish, for each bay a connecting protection zone to which the bay is connected, and
identify the orphan bay with a connecting protection zone related to the isolated bus bar segment.
11. The apparatus of claim 8 , wherein the IED is further configured to wait for a delay time of at least 0.5 seconds between the observing of the trip and the identifying of the orphan bay.
12. The apparatus of claim 8 , wherein the un-tripped bus bar segment is different from the isolated segment of the bus bar.
13. The apparatus of claim 8 , wherein the IED is further configured to issue an open command to a disconnector in the isolated bus bar segment to connect the orphan bay to the un-tripped bus bar segment.
14. The method of claim 13 , wherein the IED is further configured to issue a close command to a bay circuit breaker of the orphan bay to connect the orphan bay to the un-tripped bus bar segment.