Precision Timing for Smart Grid Systems

“Common time synchronization is the key to many Smart Grid (SG) applications for real-time operation necessary to make the Smart Grid highly robust and resilient to disturbances.”
Different types of SG measurement and control have different timing requirements and getting these heterogeneous sensors and controls to work together requires accurate timing for everything from substation timing to wide area monitoring systems. New technologies such as distributed energy resources, renewable resources, and electrical vehicles all require precision timing. To meet this need, the power industry needs not only timing protocols, but testing and measurement capabilities to help implement the timing systems. This project will build and develop performance, conformance, and interoperability test methods for the IEEE Precision Clock Synchronization Power Profile. It will also examine security vulnerabilities and mitigation methodologies for the IEEE 1588 standard.

Objective: Develop performance, conformance and interoperability test methods for the C37.238-2011 standard (IEEE Standard Profile for Use of IEEE 1588 Precision Time Protocol in Power System Applications)

What is the new technical idea? Timing synchronization for the smart grid in the millisecond and below range is necessary to support many types of smart grid functionality such as substation control systems and supervisory control and data acquisition systems. The Precision Measurement Unit (PMU) measures the electrical waveforms at a specific point on the grid.  This information is used to both control grid interactions and to analyze past events.  To combine the data from each PMU into a useful matrix, time synchronization is required.  IEEE 1588 precision clock synchronization protocol provides the ability to meet these timing requirements.  The NIST ITL Timing Testing Dashboard (TTD) will allow us to test the performance of PMU in a simulated substation network and the conformance of the PMU to the 1588 draft power profile.

What is the research plan?  

• A test suite using the TTD will be developed describing performance, conformance and interoperability test methods for the IEEE C37.238-2011.
• The dashboard will be updated to support the IEEE 1588 Power Profile.  This includes modifying the communications to handle both OSI layer 2 and layer 3 communications.  
• A simulated substation network environment will be created at NIST supporting the simulation of substation network traffic and allowing testing under typical and extreme traffic conditions.  
• Once the simulated network is complete phasor measurement units can be installed on the \ network and tested using the TTD.

Recent Results: Time Synchronization Performance Testing Dashboard

“Testing Phasor Measurement Units using IEEE 1588 Precision Time Protocol”
International Conference on Precision Electromagnetic Measurements 2012
J. Amelot, G. Stenbakken
A Phasor Measurement Unit was time synchronized using the Precision Time Protocol, calibrated by the NIST PML calibration system, and shown to accurately and reliably monitor and timestamp waveforms.

“An IEEE 1588 Performance Testing Dashboard for Power Industry requirements”
International IEEE Symposium on Precision Clock Synchronization 2011
J. Amelot, Y. Li-Baboud, C. Vasseur, J Fletcher, D. Anand, J. Moyne
To ease the challenges of testing, monitoring and analysis of the results, a software-based testing dashboard was designed and implemented. The dashboard streamlines the performance testing process by converging multiple tests for accuracy, reliability and interoperability into a centralized interface. The dashboard enables real-time visualization and analysis of the results.

“An IEEE 1588 time synchronization testbed for assessing power distribution requirements”
International IEEE Symposium on Precision Clock Synchronization 2010
J. Amelot, J Fletcher, D. Anand, C. Vasseur, Y. Li-Baboud, J. Moyne
Wide-area monitoring applications for power distribution rely on accurate global time synchronization. Furthermore, there is interest in replacing current time synchronization methods such as Inter Range Instrumentation Group (IRIG), with distributed time synchronization protocols that utilize the data communication lines eliminating the need for dedicated timing signals within the substation. By understanding the factors impacting synchronization performance, the testbed facilitates the characterization of metrics needed to meet industry requirements and provides an experimental venue to explore IEEE 1588 Precision Time Protocol (PTP) technologies and determine how new features and requirements for time synchronization can impact the performance of next-generation power distribution applications.