Presentation on theme: "RT3b – André Smit, Siemens USA"— Presentation transcript:
1 RT3b – André Smit, Siemens USA U.S. Distribution Feeder Automation Pilot ProjectWe have developed a peer-to-peer feeder automation system using WiMAX and IEC61850During the project we needed to develop new protection settings for the feederWe found that conventional settings of coordinated overcurrent relays was not possible The relay setting groups could not be adapted to all the different operating scenarios we faced We needed to find a solution that was less complicated with better performance
2 Traditional Feeder Operation Overcurrent protection operate and tripUtility receives a fault notification from a customer experiencing an outageTrouble desk dispatches a line crew to locate and isolate the faultCrew restores service to unaffected sections of lineCrew effects repairs and restores feeder to normal operationOutage time could be measured in hoursAndré Smit – U.S. – RT3b
3 Automation of the Distribution Feeder FLISRFault Location, Isolation, and Service RestorationCircuit BreakerRecloserSwitch
5 Automating the Distribution Feeder Operational Features to ConsiderChange open point based on loadingIsolate line sections for maintenanceTransfer to healthy sourceCircuit BreakerRecloser
6 Different curve shapes to deal with Relay protecting power transformer does not have same shape curve as fuse designed to protect small distribution feeder load
7 Affect when lowering the Isc The effect of moving 50 setting to indicate what happens when Isc is low.Little room to coordinate with 51 element. Cannot coordinate with 50 elementas a higher Isc will cross both lines and both relays will trip.
8 Affect without low Isc being a factor If low Isc not a factor, more space to coordinate with 51 element and still stay above fuse.
9 3 Reclosers with Tolerance Affect Typical TCC curve showing high and low tolerances. (Used ±5% on pickup & time.)Not considering CT tolerance. Illustrates need for space between curves.
10 1 RecloserOnly one recloser easy to fit between max fuse and feeder main breaker.Better coordination (more space) between all four devices.
11 One set of TCC curves of 16 sets Using four total setting groups 51 pickup markersMatch curvesto databy colorLargest downstream fuseFeeder main breaker and three reclosersUpstream Transformer or Bus Main Breaker50 active only during reclose
12 One set of TCC curves of 16 sets Using four total setting groups 51 pickup markersMatch curvesto databy colorLargest downstream fuseFeeder main breaker and three reclosersUpstream Transformer or Bus Main Breaker50 active only during reclose
13 Difficulties in Coordinating Feeder Reclosers are in series on feeder and not located on branchesSegments have different types of loadsCurves for transformers are not as steepDemand changes by time of day and season and differently for each segmentMelt/time characteristics for distribution fuses do not fit closely with substation transformer protection upstreamOriginal system designed without new switching points
14 Difficulties in Coordinating Feeder High source impedance + long line = very low fault currentsSubstations located at the ends of the line, so source impedance is usually high; a long feeder—the best candidate for automation—adds to the impedanceSevere limits caused by existing minimum current settings and low short circuit current (Isc)Low available Isc limits use of 50, or 50 with definite timeMust include considerable allowance for high-impedance branch line faults causing Isc to be even lowerInrush current could be five times nominal current, therefore precluding the use of 50 element when Isc is low
15 How do we deal with these difficulties to protect an Automated Feeder? Setting Sheets
16 Our SolutionDetect and isolate faults with a differential (87L) functionActivate a 50/51 overcurrent curve on one device end and reclose on faultDiff ZoneDiff ZonePrimarySwitch 1PrimarySwitch 2PrimarySwitch 3878787878787Relay 1Relay 2Relay 3