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Time Synchronisation
- 1. Confidential © Copyright2013 Doug Arnold Principal Technologist, Symmetricom & IEEE 1588 Study Group Co-Chair 23 May 2013 Time Synchronisation
- 2. 2Confidential © Copyright2013 IEEE C37.238-2011 Timing (PTP Power Profile) IEC 61850 Smart Substation: Industrial Ethernet Infrastructure With PTP Relay Relays Phasor Measurement Units Control Center Bay Controller Bay Controller Gateway Communication Bus NO INDEPENDENT TIMING DISTRIBUTION Communication Bus Intelligent Switchgear NextGeneration CT/PT(VT) IEEE C37.238-2011 Timing HMI Station Controller Substation Clocks Station Bus Merging Unit CT/PT (VT) Switchgear Process Bus Relays
- 3. 3Confidential © Copyright2013 Traditional Smart Grid Substation Applications: Time Accuracy Requirements AccountingOperationsForensics Phasor Measurements Sampled Values Traveling Wave Fault Locator Lightning Strike Correlation SCADA/EMS Frequency Measurement Protection Relaying Events Event/Disturbance Recorders Quality of Supply Metering Bulk Metering Customer Premises Metering 1.0 second 0.5 second 1 millisecond 1 microsecond Application Accuracy
- 4. 4Confidential © Copyright2013 Do 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 sabotage such as jamming and spoofing GPS antenna farms are created from multiple point solution implementations. Some of the issues that can impact your timing reference:
- 5. 5Confidential © Copyright2013 IEC 61850 Smart Substations: Process Bus To The Switchyard Current Practice • Parallel copper cabling between switch yard & control building • Analog samples to protection equipment • Coaxial cables for IRIG timing Source GE Protection & Control Journal October 2008 Future Systems • Fiber optic network IEC 61850 Process Bus • Digitized sampled values to protection equipment • Timing on data network • Increases reliability & control • Provides isolation • Lowers cost
- 6. 6Confidential © Copyright2013 Benefits of having a timing strategy The benefit of having a timing strategy is to ensure that you have a single accurate and reliable time reference within and across your substations. IEEE 1588 Telecom Profile Grandmaster IEEE 1588 PTP WAN synchronization #1 #2 #3 Rubidium Holdover GPS Substation Master Clocks Alarm Status SNMP Monitoring #4 Remote Management Your timing architecture should consider the following elements: 1. Redundant hardware and primary reference 2. Backup time references 3. Holdover 4. Management
- 7. 7Confidential © Copyright2013 Time Transfer Technologies IRIG-B (S)NTP PTP Accuracy (typical) 1-10ms 1ms – 10 ms 100ns-1ms Transport media Dedicated cables Ethernet cables Ethernet cables Protocol style Master-slave Client-server Master-slave Built in latency correction No Yes Yes Set-up Configured Configured Self-organizing, or configured Update intervals 1 second Minutes 1 second Specialized hardware Required No Required Redundant masters for N-1 contingency No Yes Yes
- 8. 8Confidential © Copyright2013 What a Network Looks Like to PTP
- 9. 9Confidential © Copyright2013 Transparent Clock Cable delay Cable delay Residence Time Total delay = cable delays + switch residence time SYNCFollow Up
- 10. 10Confidential © Copyright2013 PTP 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 performance requirements 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. 11Confidential © Copyright2013 IEC 61588 - Power Profile Standard • IEEE C37.238-2011 Standard - Profile for IEEE 1588 Precision Time Protocol in power system applications • Profile Characteristics: - LAN (Layer 2 Ethernet Mapping) - Multicast addressing only - Switches must be PTP enabled - Time transfer accuracy and holdover time defined • IEC 61850 will add C37.238-2011 as a requirement in the future. • http://standards.ieee.org/findstds/stan dard/C37.238-2011.html
- 12. 12Confidential © Copyright2013 Backup Primary Reference with Telecom Profile PTP Substation • GPS primary reference • PTP Grandmaster • Telecom Profile slave IEEE 1588 Telecom Profile Grandmaster
- 13. 13Confidential © Copyright2013 • 25 substations with PMUs in northern California, USA • Transmission elements monitored by PMUs – Broad regional footprint monitored by PMUs – Voltage monitored at 60-500kV – Many installations line voltage • PDCs in 13 field locations, fully redundant • Communication System availability –Redundant architecture – Production system (designed for 99.95% - outage of 4.5 h/year) Synchrophasor Project Oregon California Lake Tahoe COTP AC INTERTIE Nevada - Oregon Border (NOB) DC PMU locations Super PDC locatios
- 14. 14Confidential © Copyright2013 PG&E Timing Objectives for the Synchrophasor Project
- 15. 15Confidential © Copyright2013 PG&E Deployment
- 16. 16Confidential © Copyright2013 Smart Substation WAN/LAN Timing Solution IRIG-B Bus RELAY ROOM Event Recorder IRIG-B C37.118.1-2011 Protection Schemes Remote Terminal Unit (RTU) PPS, PPM SubstationClock GPS/GNSS ADM DS1 G.703 9/13 COMMUNICATION ROOM IEEE 1588 GMC TP5000, SSU 2K, Time Hub IEEE 1588 PTP Telecom Profile Utility WAN SONET/SDH Protection Relay Alarm Annunciator Substation Gateway Substation Switch (Transparent Clock) LAN IEEE 1588 PTP Power Profile PMU PDC
- 17. 17Confidential © Copyright2013 Summary • Using PTP for time distribution in substations is most accurate with lowest TCO • GPS vulnerability is real and needs to be mitigated • Point solutions will not scale and will become impossible to manage • Don’t limit your options. Have a strategy to transition from a traditional substation to a smart substation. • Time sync will continue to increase in importance. Quality and expertise matter.
- 18. 18Confidential © Copyright2013 Thank You Doug Arnold darnold@symmetricom.com 707-537-7902 Debbie Henderson dhenderson@symmetricom.com 408-428-7911