Time Synchronisation


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Time Synchronisation

  1. 1. Confidential © Copyright 2013Doug ArnoldPrincipal Technologist, Symmetricom & IEEE 1588 Study Group Co-Chair23 May 2013Time Synchronisation
  2. 2. 2Confidential © Copyright 2013IEEE C37.238-2011 Timing(PTP Power Profile)IEC 61850 Smart Substation:Industrial Ethernet Infrastructure With PTPRelayRelaysPhasorMeasurementUnitsControl CenterBayControllerBayControllerGatewayCommunicationBusNO INDEPENDENT TIMING DISTRIBUTIONCommunicationBusIntelligentSwitchgearNextGenerationCT/PT(VT)IEEE C37.238-2011 TimingHMIStation ControllerSubstation ClocksStation BusMerging UnitCT/PT (VT)SwitchgearProcess BusRelays
  3. 3. 3Confidential © Copyright 2013TraditionalSmart GridSubstation Applications:Time Accuracy RequirementsAccountingOperationsForensicsPhasor MeasurementsSampled ValuesTraveling Wave Fault LocatorLightning Strike CorrelationSCADA/EMSFrequency MeasurementProtection Relaying EventsEvent/Disturbance RecordersQuality of Supply MeteringBulk MeteringCustomer Premises Metering1.0 second 0.5 second 1 millisecond 1 microsecondApplicationAccuracy
  4. 4. 4Confidential © Copyright 2013Do you have a timing strategy?If not, you may have issues and not know it.• Improper antenna installations• Damaged antennas causing interference• Environmental conditions• Intentional and unintentional sabotagesuch as jamming and spoofingGPS antenna farms are created from multiple pointsolution implementations. Some of the issues thatcan impact your timing reference:
  5. 5. 5Confidential © Copyright 2013IEC 61850 Smart Substations:Process Bus To The SwitchyardCurrent Practice• Parallel copper cabling betweenswitch yard & control building• Analog samples to protectionequipment• Coaxial cables for IRIG timingSourceGE Protection & Control JournalOctober 2008Future Systems• Fiber optic network IEC 61850Process Bus• Digitized sampled values toprotection equipment• Timing on data network• Increases reliability & control• Provides isolation• Lowers cost
  6. 6. 6Confidential © Copyright 2013Benefits of having a timing strategyThe benefit of having a timing strategy is to ensure that you have a singleaccurate and reliable time reference within and across your substations.IEEE 1588 TelecomProfile GrandmasterIEEE 1588 PTPWAN synchronization#1#2#3 RubidiumHoldoverGPSSubstation Master ClocksAlarm StatusSNMP Monitoring#4Remote ManagementYour timing architecture should considerthe following elements:1. Redundant hardware and primaryreference2. Backup time references3. Holdover4. Management
  7. 7. 7Confidential © Copyright 2013Time Transfer TechnologiesIRIG-B (S)NTP PTPAccuracy (typical) 1-10ms 1ms – 10 ms 100ns-1msTransport media Dedicated cables Ethernet cables Ethernet cablesProtocol style Master-slave Client-server Master-slaveBuilt in latencycorrectionNo Yes YesSet-up Configured ConfiguredSelf-organizing, orconfiguredUpdate intervals 1 second Minutes 1 secondSpecialized hardware Required No RequiredRedundant mastersfor N-1 contingency No Yes Yes
  8. 8. 8Confidential © Copyright 2013What a Network Looks Like to PTP
  9. 9. 9Confidential © Copyright 2013Transparent ClockCable delay Cable delayResidence TimeTotal delay = cable delays + switch residence timeSYNCFollow Up
  10. 10. 10Confidential © Copyright 2013PTP Profiles• PTP options– Many optional features– Works over many network types– Used in several different industries– Interoperability between PTP enabled devices is not guaranteed!• Profiles– Purpose is to ensure interoperability and meet performancerequirements for a specific application– More restrictive set of rules than PTP– Popular profiles• Power Profile, IEEE C37.238-2011• Telecom Profile, ITU G8265.1• Audio-Visual Profile, IEEE 802.1AS
  11. 11. 11Confidential © Copyright 2013IEC 61588 - Power Profile Standard• IEEE C37.238-2011 Standard- Profile for IEEE 1588 Precision TimeProtocol in power system applications• Profile Characteristics:- LAN (Layer 2 Ethernet Mapping)- Multicast addressing only- Switches must be PTP enabled- Time transfer accuracy and holdovertime defined• IEC 61850 will add C37.238-2011 as arequirement in the future.• http://standards.ieee.org/findstds/standard/C37.238-2011.html
  12. 12. 12Confidential © Copyright 2013Backup Primary Referencewith Telecom Profile PTPSubstation• GPS primary reference• PTP Grandmaster• Telecom Profile slaveIEEE 1588 TelecomProfile Grandmaster
  13. 13. 13Confidential © Copyright 2013• 25 substations with PMUs in northernCalifornia, USA• Transmission elements monitored by PMUs– Broad regional footprint monitored byPMUs– Voltage monitored at 60-500kV– Many installations line voltage• PDCs in 13 field locations, fully redundant• Communication System availability–Redundant architecture– Production system (designed for99.95% - outage of 4.5 h/year)Synchrophasor ProjectOregonCaliforniaLakeTahoeCOTPACINTERTIENevada - Oregon Border(NOB)DCPMU locationsSuper PDC locatios
  14. 14. 14Confidential © Copyright 2013PG&E Timing Objectives for theSynchrophasor Project
  15. 15. 15Confidential © Copyright 2013PG&E Deployment
  16. 16. 16Confidential © Copyright 2013Smart Substation WAN/LAN Timing SolutionIRIG-B BusRELAY ROOMEventRecorderIRIG-BC37.118.1-2011Protection SchemesRemoteTerminalUnit (RTU)PPS, PPMSubstationClockGPS/GNSSADMDS1G.703 9/13COMMUNICATION ROOMIEEE 1588 GMCTP5000, SSU 2K,Time HubIEEE 1588 PTPTelecom ProfileUtility WANSONET/SDHProtectionRelayAlarmAnnunciatorSubstationGatewaySubstation Switch(Transparent Clock)LAN IEEE 1588 PTPPower ProfilePMUPDC
  17. 17. 17Confidential © Copyright 2013Summary• Using PTP for time distribution in substations is mostaccurate with lowest TCO• GPS vulnerability is real and needs to be mitigated• Point solutions will not scale and will becomeimpossible to manage• Don’t limit your options. Have a strategy to transitionfrom a traditional substation to a smart substation.• Time sync will continue to increase in importance.Quality and expertise matter.
  18. 18. 18Confidential © Copyright 2013Thank You Doug Arnolddarnold@symmetricom.com707-537-7902Debbie Hendersondhenderson@symmetricom.com408-428-7911