Building Synchrophiezed Measurement Systems for Future Grid Operations

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

In the past twenty years, ComEd has witnessed major changes not only in its own territory but across the entire Eastern Interconnection. The noticeable changes include the increasingly high penetration of inverter-based resources, resulting from public-policy driven increases in the amount of wind and solar generation and the retirement of multiple coal generation plants. The pace of change is anticipated to quicken in the foreseeable future as many states in the US are moving towards a low or no carbon electrical power supply future. As a result, the operating conditions of the current ComEd have been changed and will continue to change. The operating conditions of the future ComEd system grid will be very different from today’s operating conditions. Reduced system inertia, decreased short circuit current, and faster system dynamic response are already happening, and will become more pronounced in a future power grid.
Many on-going initiatives are aimed to continue improving the reliability performance metrics through modernize ComEd’s distribution systems. ComEd envisioned that it could become a network service provider/integrator (NSPI) for distribution systems to provide a variety of services to existing and new types of customers and partners as part of its Utility of the Future roadmap. Realizing this vision would require a much greater visibility and controllability of its T&D systems.

In response to and in anticipation of continued operation condition changes in the ComEd and the Eastern Interconnection control areas, ComEd has embarked on many initiatives to modernize its transmission grid and distribution networks. Adopting new technologies, such as synchronized measurement technology, to improve and enhance ComEd operations is one of these major initiatives. For example, as inverter-based generation does not have inertia, any changes in the system happened faster and require better visibility across the interconnected grid. Synchronized measurements, with their 1 microsecond accuracy allow for much faster tracking of the events than conventional EMS/SCADA and through GPS synchronization visibility of the events across the grid. Furthermore, data sharing across neighboring utilities is important to address fast grid events. Exelon companies (ComEd, BGE, PECO, and PEPCO Holdings) are working together to both build a robust, productized system and to allow for data sharing across the grid.

Deploying synchrophasor technology for future grid operations: ComEd’s early involvement with the synchrophasor technology started after the 2003 blackout through participation in the Eastern Interconnection Phasor Project (EIPP) and later in the North American Synchro-Phasor Initiative (NASPI) activities.
ComEd’s experience with synchrophasor technology deployment and application stems back to 2009, when it first joined a PJM-led project co-funded by the U.S. Department of Energy through the Smart Grid Investment Grant (SGIG).  Through the PJM synchrophasor project and ComEd’s own follow-on efforts, ComEd has acquired a great deal of knowledge and proficiency with the deployment of synchrophasor systems and the use of the valuable information they provide.  For example, synchrophasor data greatly improves the accuracy and speed of the post-event analysis and the information has been found valuable in identifying events and issues that were not visible before with other tools/systems. It is also part of the data sets required for meeting NERC PRC-002-2 requirements.
This positive experience, coupled with the knowledge gained through active participation at NASPI, NERC, and IEEE activities, has shown that synchrophasor technology could play a major role in economical and reliable operation of the future ComEd transmission grid and distribution systems.

For offline applications, in addition to post-event analysis, model validation ensures that system operating safety margins are based on accurate generator, load, and system models that allow for the maximum capacity of the transmission grid to be utilized.
Real-time synchrophasor applications that enhance ComEd’s transmission grid operations include: Linear State Estimator for real-time data validation, and Online Model Monitoring and Adjustment for keeping the models updated in real-time; Fast System Condition Assessment after forced outages; Voltage Stability Analysis, Island Operation and System Restoration Support; Wide-Area Voltage/VAR Control; and Wide-Area System Integrity Protection Schemes.
Synchrophasor could also be applied to improve ComEd’s distribution operations in five functional areas through (1) improve/enhance classical and modern distribution functions with the use of synchrophasors, and (2) implement advanced and future distribution functions that depend on synchrophasors. The five functional areas are: distribution system operations, distributed energy resource (DER) integration, system monitoring, protection, automation and control, asset management and reliability, and planning and analysis.
However, integrating synchrophasors into ComEd’s day-to-day operations requires sizable investment to deploy the technology in ComEd’s transmission grid and distribution systems. For example, to achieve a full observability of the transmission grid and increase the number of practical applications, it will be needed to substantially increase the number of PMUs, improve data quality, increase redundancy, and ensure the deployed synchrophasor systems to comply with NERC CIP standards.

Relion advanced protection & control.
BeijingSifang June 2016