Precise Time Synchronization for Substation Automation purposes.

What is time synchronization and how does it work? Which solutions exist for power transmission and distribution systems? What is precision, accuracy and resolution and why should manufacturers and operators of equipment for electrical distribution networks care about these terms? This document has been created to answer these questions and offers you a comprehensive and easy-to-understand introduction. Read on ...

• Time Synchronization Overview
• Time Synchronization Equipment
• Examples of use
• Time Synchronization Terms and Glossary

Time Synchronization Overview

Direct Synchronization

GPS Antenna Dedicated Clocks

Resolution and precision: 1 ms for events and faults in substation synchronization PPS (Pulse per second as a hardware Gong) 1 kPPs with 250 ns precision for sinchrophasor relays (Resolution of+/-5 µs) Electrical/ Optical Prot. Siemens ® S/S equipment Control Protection Billing metering SOE and fault recording Frequency deviation Δf, ΔT ABB Codes IRIG AB Afnor DCF Pulses PPS-PPM 1 kPPS PPH

Syncronization over LAN

• Depends on traffic on the network
• Depends on distance and communication media
• Range from submiliseconds to 5 -20 ms

SCADAs Communications processors LANs S/E

Protocols

DNP 3.0 IEC 60870-x IEC 61850  NEW!  IEEE 1588-2002 UCA 2 (MMS) * Other

Synchronization over LAN

• External networks are getting bigger in control and protection environments through:
  • LAN, WAN, MAN
  • Redundant LANs
  • Switches, routers, firewalls
  • Severs and clients
  • Communication over Internet and Intranets
  • Different medias
• Transmission of secure data on insecure channel:
  • Confidenciality
  • Integrity
  • Authentication
• Tools:
  • Encrypted tunnels
  • VPN

Synchronization Equipment from Meinberg

• Clocks for SCADAs, RTUs, PLCs, relays, automation
  • PPH, PPM, PPS
  • Optical outputs
  • DCF, IRIG A/B Codes, etc.
  • Proprietary codes: SIEMENS, ABB, ION etc.
  • Frequencies/Amplitudes: Fixed and variable
  • Frequency measurement
  • PCI cards
  • Special signals and interfaces
  • Slave clocks
  • Wide AC and DC power supply ranges
  • Mounting on 19" Rack, DIN rail
  • Antenna with cable up to 300 meters, optical available

Examples of Use

• Time Synchronization with GPS170BGT - LAN-CPU
• Time Synchronization with customized GPS170BGT
• Time Synchronization with GPS-Signal Distributor

Time Synchronization with GPS170BGT - LAN-CPU

Time Synchronization with customized GPS170BGT

Time Synchronization with GPS-Antenna Distributor GPSAV4

What is Accuracy? Accuracy (Precision) Commonly based on UTC Micro or nanoseconds Referenced against the PPS in the GPS system always given by the clock e.g. +/- 250ns or 100 ns to PPS
What is Resolution? The smallest possible time difference between two event recordings(in S/S = 1ms) Chronological correctness always depends on the end device internal sampling rate Processor and bus speeds	t 1 = 15:05:26:374 t 2 = 15:05:26:375 t 3 = 15:05:26:376
Usual signals for time synchronization in electrical systems: IRIG-B mod IRIG-B unmod PPS DCF_MARK SERIAL CODES Each signal type has its own resolution e.g. IRIG-B: The framerate is 1.0 second - but accuracies up to 1 μs can be achieved B00x Resolution of 10 ms (dc level shift) B12x Resolution of 1 ms (modulated 1kHz carrier) Stability What means a free running clock? Clock without external disciplining signal Loss of GPS signal GPS antenna or cable failure, damaged receptor In the case of free running clock the oscillator maintains the accuracy with a certain precision for a certain time. Stability of a clock depends on the oscillator!! Oscillators of different qualities: TCXO Temperature Controlled Oscillator OCXO LQ-MQ-HQ Oven Controlled Oscillator OCXO DHQ Double Oven Oscillator Rubidium/ Cesium/ Other sources Oscillator stability determines free running clock precision (without GPS). Comparison in 1 day or 1 year time frames The more stable an oscillator, the smaller the time deviaton of the free running system from UTC Here you can find a comparison chart of our oscillators: Oscillators comparison Internet adresses of IEDs and other related equipment manufacturers ABB ABB Automation Areva Arteche Basler Electric Beckwith Electric CEE Cooper DEIF Fanox GE Industrial GE Power Gen Japan AE PSE(Hitachi) MicroElettricaScientifica NxtPhase Orion Italia P&B Eng Qualitrol Reyrolle RFL Schneider Schneider Sepam SEL Schweitzer Eng SEG Siemens Solcon Startco Thytronic Vamp ZIV Equipment for Electrical Systems and Power Plants Relays - Protective Motor Protection Relay Motor Management Relay Generator Management Relay Blocking and Test Module Feeder Relay Transformer Management Relay Feeder Management Relay Advanced Line Protection System Bus Differential Relay Bus Differential Relay System Percentage Differential with Harmonic Restraint Bus Bar Protection Controller System Breaker Protection System Capacitor Bank Protection and Control System Offset Mho Directional-distance Loss of Excitation Relay Angle Impedance Relay Reactance and Mho Phase Directional-distance High Speed Differential Relay Voltage-balance Relay Instantaneous Overcurrent Relay Remote CAN I/O Module Line Distance Relay Line Distance Protection System Digital Breaker Failure Digital Breaker Supervision Distributed Digital Fault Recorder Digital Distribution System Digital Frequency Relay Digital Generator Protection Single Phase Digital Overcurrent Protection Digital Line Protection System Digital Multifunction System Numerical Single-Phase and Three-Phase Reclosing System Digital Transformer Protection Transformer Tap Changer Controller Terminal Boards Multiple Feeder Management Relay Bay Controller Generator Management and Control System Phase Packaged Directional-distance Relay Substation Automation Power Directional Relays Ground Distance Relay Automatic Synchronizing Relay Auxiliary or Annunciator Relay Multicontact Auxiliary Relay Hinged Armature Auxiliary Relay Single-shot Reclosing Relay High Impedance Differential Module Multicontact Hand Reset Auxiliary Relay Time-overcurrent Relay Time Delay Voltage Relay Directional Overcurrent Relay Directional Ground Overcurrent Relay Phase Sequence and Undervoltage Power Directional Protection Relay TOC Relay with Voltage Restraint Current Balance Relay Percentage Differential Relay Synchronism Check Relay Phase and Ground Overcurrent Relay Line Phase Comparison Relay Line Current Differential Relay Modular Low Voltage Motor Protection System Line Protection System Generator Backup/Out-of-Step Protection Modular Microprocessor Relays Digital Generator Protection Relay High Impedance Busbar Differential Relay Digital Overcurrent Relay Digital Distribution System Family Digital Feeder Relay Machine Protection Relay Generator Protection System Digital Ground Protection Voltage/Frequency M Family Relay Voltage/Frequency MII Family Relay Directional Power/Loss of Field Directional Power Protection System Digital Synchronism Check Relay Intelligent MCC Controller Low Voltage Motor Management System Digital Multifunctional Protective Relay Motor Protection Meter Network Stability and Synchrophasor Measurement System Auxiliary Relay Voltage Unbalance Relay Voltage Relay Machine Field Ground Relay Instantaneous Voltage Relay Power Management Control System PVD Differential Voltage Relay High Speed Trip and Lockout Relay Remote RTD Module Static Timing Relay Control and Transfer Switches Catalog Master Control Switches Static Breaker Backup Relays Differential Voltage Relay Control and Transfer Switches Static Directional Comparison Blocking Relay Static Digital Frequency Relay Negative Sequence Overcurrent Static Synchronism Check Relay Feeder Management System Synchronous Motor Protection & Control STD Percentage Differential with Harmonic Restraint Overexcitation Relay Modular Power Reversal Relay Modular Voltage Relay Tripping and Blocking Rectifiers Protection Relays Universal Recloser Control Wind Generator Protection System Power Quality Meter Electronic Power Meter Instrument Transformers