Building Synchrophiezed Measurement Systems for Future Grid Operations

Authors: David Schooley, ComEd, Yi Hu and Damir Novosel, Quanta Technology, USA

Redundancy was one of the goals for the production PMU data system. Redundancy is achieved through local redundancy of the PDCs and by utilizing duplicate data centers. The PDC servers consist of 2-machine clusters of one active server and a hot inactive server. If the active server fails or needs to be taken out of service for maintenance, then the cluster will fail over to the inactive server within a few seconds.
To further enhance redundancy, the WASAS and WAMS systems are duplicated at two geographically separated data centers. The installations at the data centers are identical for the production components of the WASAS and WAMS systems. Each of the two-data center WASAS installations will eventually send data to PJM, providing duplicate streams and redundancy at the ISO level. Auxiliary components, such as the development and quality assurance environments, do not require the same level of redundancy and are only implemented at a single data center. An example of how the data-center redundancy works with the real-time RTDMS application is shown in Figure 5.

OSISoft’s PI Historian is the long-term data storage solution chosen for the synchrophasor data. The PI enables high-availability access to data with support for multiple servers. The high availability function of the PI automatically allows for selection of an active server without a need for user intervention.

ComEd utilizes substation PDCs as part of its standard design for transmission and PMU deployment. Each substation PDC sends data to both data centers at the same time. If one data center loses connectivity, the PMU data will still be accessible at the other data center. As with the data center design, the substation PMU/PDC implementation is designed to be upgradable as CIP requirements change in the future. The goal in the design is to not have to remove any equipment as requirements change, only to add equipment such as card readers and firewalls as necessary. The substation configuration makes a substation “PMU ready,” which enables future PMUs to be added for a low cost.
The WAMS is in use today for engineering and event analysis. The WASAS is implemented but not entirely separated from WAMS, with the real-time tools in use for evaluation of capabilities such as oscillation detection and analysis. The WAMS and WASAS design has allowed ComEd to increase its PMU deployment from 12 PMUs at 7 substations to 44 PMUs at over 20 substations in less than two years. ComEd’s goal is to install 50 PMUs per year in a combination of planned projects and as additions to other reinforcements. Following WASAS applications are planned to be deployed in next 3 years: linear state estimation, on-line model calibration, fast contingency analysis, voltage stability monitoring, and islanding and system restoration support.

ComEd distribution networks synchrophasor technology deployment:  ComEd has initiated a pilot program to begin evaluating distribution synchrophasor application for selecting high-value applications for pilot implementation and to support existing projects such as microgrids and voltage optimization. The roadmap effort identified a large number of possible distribution synchrophasor applications. The distribution organization has gone through a rigorous evaluation process and selected a subset of these applications for pilot evaluation in the near future. Some of these applications, such as verification of dynamic load models will incorporate both transmission and distribution PMU data. The pilot program is already providing opportunities for staff to gain experience working with large data sets.
The distribution pilot is currently sharing the infrastructure and applications put in place to support the transmission synchrophasor deployment project, but the distribution synchrophasor systems will eventually migrate to use their own PDCs and applications. The distribution PMU data resides within the WAMS area of ComEd’s transmission grid synchrophasor system where it is available for analysis with fewer cyber security restrictions.

Deployment activities in other Exelon sister companies: Given the success of ComEd’s synchrophasor deployment, the next step is for other Exelon companies in the mid-Atlantic region (BGE, PECO, and PEPCO Holdings) to build a similar system. Exelon is currently consolidating its EMS at two data centers for these mid-Atlantic utilities and these data centers will also support the synchrophasor system infrastructure. Data sharing between the mid-Atlantic utilities and ComEd will be incorporated into the final design. ComEd will take advantage of the lessons learned in data sharing with its sister utilities as a path toward implementing similar data sharing with its neighbors who are not members of PJM.
While the IT systems will be identical to what was installed to support PMUs at ComEd, the geographical separation between the utilities in the mid-Atlantic will pose some challenges. Engineers in the mid-Atlantic utilities will be able to access the ComEd data and applications in preparation for the eventual deployment of the mid-Atlantic synchrophasor systems for use by these utilities.

Concluding remarks:  As the energy supply is quickly moving towards a low/no carbon future, it is expected that new challenges in operating such future power system will continue to emerge. Synchronized measurement technology should be an integral part of overall solution in addressing these challenges.
It is clear that integrating synchrophasors into real-time and non-real-time operations is a major undertaking that requires substantial investment and a careful planning to ensure a successful deployment for realizing the intended benefits.
ComEd’s roadmap development exercise and the deployment experience so far has indicated that it is extremely important to start the planning of such deployment for future grid operation as early as possible, as it will take at least 4-5 years before the deployed systems become operationally ready.  



David C. Schooley is a Principal Engineer in the Transmission Analysis department at ComEd (Exelon Utilities.) His Bachelor of Science and Master of Science degrees in Electrical Engineering are from Oklahoma State University, and his Ph.D. degree in Electrical Engineering is from the Georgia Institute of Technology, where he studied the integration of large amounts of wind and solar energy into the generation mix. His job responsibilities have included work in both transmission operations and planning. David is the Exelon lead for PMU deployment and applications.

Yi Hu Director of Quanta Technology, has over 30 years’ experience and is a leading expert in the synchronized measurement based Wide-Area Monitoring, Protection, automation, and Control systems deployment and applications.
Dr. Hu is an IEEE fellow who had contributed to the development of several synchronized measurement technology related IEEE standards. He currently chairs an IEEE working group to develop an “IEEE Guide for Engineering, Implementation, and Management of System Integrity Protection Schemes.” Yi holds 13 U.S. patents, and has published multiple technical papers and articles in Refereed Journals and Conference Proceedings.

Dr. Damir Novosel is president and founder of Quanta Technology, a subsidiary of Quanta Services, a Fortune 500 company.  Previously, he was vice president of ABB Automation Products and president of KEMA T&D US. Dr. Novosel is member of US National Academy of Engineers and served as IEEE PES President and Vice President of Technical Activities. He is also a member of the CIGRE US National Committee and received the CIGRE Attwood Associate award.  Damir holds 17 US and international patents, published over 140 articles, and contributed to 5 books.

BeijingSifang June 2016