Presentation on theme: "IED Time Synchronization John Levine, P.E. Levine Lectronics and Lectric."— Presentation transcript:
IED Time Synchronization John Levine, P.E. Levine Lectronics and Lectric
2 MultiSync 100 1588 GPS Clock Why do we need to synchronize our relays? Relays at all three locations tripped. All three had different times. Are these events related???
3 MultiSync 100 1588 GPS Clock Definitions the marking of an event with respect to a reference origin. GPS time signals, based on the atomic clock in GPS satellites, are the reference origin. Time a measurement of duration between events. Time interval a time system adopted in 1972. UTC is based on the weighted combination of atomic clocks located around the world. UTC occasionally changes by the addition of leap seconds. Coordinated Universal Time (UTC) High-precision atomic coordinate time standard, basis for UTC. 35 seconds ahead of UTC. International Atomic Time (TAI) the measure of the number of events that occur within a time interval, such as the number of oscillations of a voltage waveform within one second Frequency
4 MultiSync 100 1588 GPS Clock QMI 5/28/2014 GPS GPS Satellite Navigation System uses precise time measurements to measure the distance between a receiver and satellites GPS satellites use atomic clocks for accuracy GPS satellites are the source of timing signals for clock applications ±100 nanosecond accuracy GPS time is not UTC time UTC time adds leap seconds, GPS does not GPS time is 16 seconds ahead of UTC
5 MultiSync 100 1588 GPS Clock QMI 5/28/2014 NTP / SNTP Network time protocol (NTP) networking protocol for clock synchronization between devices operating over packet-switched, variable-latency data networks. Calculates round trip delay Doesn’t accurately cover switch delays, network traffic, reconfigurations Benefits to NTP Uses SCADA Ethernet network Good enough for SOE Detriments to NTP Accuracy in the ms range Not sufficient for synchrophasors
6 MultiSync 100 1588 GPS Clock QMI 5/28/2014 IRIG-B IRIG Formats developed by U.S. Military IRIG-B is 1 specific format used in utility and industrial applications IRIG-B is an analog signal Uses voltage pulses on copper wire Pulses indicate time from fractions of second from midnight, date from January 1st Benefits of IRIG-B Proven Sub- μs accuracy Detriments of IRIG-B Number of devices, distance limited by voltage drop Redundancy difficult Requires careful wiring design Must have an antenna for each clock location
7 MultiSync 100 1588 GPS Clock QMI 5/28/2014 IEEE 1588 IEEE Std. 1588 - 2008 IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. a.k.a. “PTP” or “Precision Time Protocol” Message based protocol for packet based networks Nano-second accuracy possible Uses TAI time
8 MultiSync 100 1588 GPS Clock Challenges to network time synch Ethernet switches Buffering adds delays Pause frames add delays Multiple master clocks possible Determining the master clock Network segmentation Determining the master clock
9 MultiSync 100 1588 GPS Clock QMI 5/28/2014 How 1588 works (peer-to-peer) C37.238 Message based synchronization to measure peer delays Best Master Clock (BMC) algorithm determines the best Master to use BMC runs continuously for network changes Synchronize through message transactions by measuring peer-to- peer delays between devices Each Peer measures delay between devices using Pdelay_Req and Pdelay_Resp Switches measure queuing delay internally Calculations are between devices
11 MultiSync 100 1588 GPS Clock Modern Time Synchronization by GE Add 1588 capabilities for future expansion while supporting in-service IRIG-B devices
12 MultiSync 100 1588 GPS Clock QMI 5/28/2014 Redundant clocks for reliability All devices have clocks All 1588 clocks run BMC Will choose best clock source based on BMC algorithm, switch configuration Clock in individual devices will choose the second clock if the first clock is unavailable. Redundancy for critical applications like wide area control through synchrophasors, process bus
Your consent to our cookies if you continue to use this website.