Building Synchrophiezed Measurement Systems for Future Grid Operations

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

ComEd synchrophasor technology deployment roadmap:  Given the sizable investment required and many activities involved for transitioning synchrophasor from pilot to production use, a synchrophasor deployment roadmap was developed. The objective of the roadmap is to provide a high-level guidance for the investment and activities required for successfully deploying synchrophasor technology within ComEd’s service territory on its transmission grid and distribution system.

The synchrophasor roadmap development has considered the following interdependencies (see Figure 1)
1. The synchrophasor applications selected for deployment are highly dependent on key business needs and drivers that various stakeholders desired to address, and
2. The required supporting infrastructure (i.e., PMUs, PDCs, Phasor Gateways, data storage systems, communication channels and networks, analytical applications, system design choice) are dependent on the synchrophasor applications being selected.

Although realizing the full benefits would require the development of proper operation processes and procedures and the necessary user training, this generally is done by operation units and not part of a high-level deployment roadmap.
With the above considerations, the roadmap development has gone through the 1) information collection and analysis, 2) identification of ComEd key business needs and drivers and the applications that address them, 3) business case development, 4) deployment readiness assessment, and 5) synchrophasor application deployment prioritization processes.
The business case development was a cost-benefit analysis based on potential benefits and benchmark cost estimations. The results of the analysis are positive that in a ten-year period the benefits would outweigh the deployment cost.
A qualitative deployment readiness assessment was also performed for synchrophasor deployment in transmission grid and distribution system. The assessment takes into consideration of several areas including required PMU installation, available communication infrastructure, CIP Compliance requirements, application maturity, product availability, and deployment efforts required.

Considering that there are hundreds of “synchrophasor-ready” devices in ComEd’s transmission grid and an extensive optical telecommunication network already installed on the ComEd transmission system, there is already a high level of readiness for a more wide-scale production use of synchrophasor technology by ComEd. However, considering the difference in CIP compliance requirements for synchrophasor applications deployed for non-real-time operation use and for real-time operation use, the following deployment roadmap for transmission operations has been selected, which includes:
1. Enable PMU functions in digital relays at all 345kv and select 138kV transmission substations
2. Deploy a real-time synchrophasor system, i.e. a wide-area situational awareness system (WASAS), for real-time operation use at the transmission grid control center
3. Deploy a non-real-time synchrophasor system, i.e. a wide-area measurement/monitoring system (WAMS), for all non-real-time operation use by authorized ComEd users
4. Set up communication network to support secure and quality of service assured data transfer between substations and the real-time and non-real-time systems

As shown in Figure 2, the deployment involves three stages, the jump-start stage (year 1 and 2), the full deployment stage (year 3 through 5), and the integration and enhancement stage (beyond year 5). Making production WAMS operation ready is the focus of the jump-start stage and deploying a production WASAS will be the focus of the full deployment stage.
Taking into consideration that for distribution systems, CIP compliance is not a requirement, synchrophasor has not been piloted before, generally communication infrastructure for synchrophasor is not readily available, and the diversity of different types of distribution circuits, the deployment roadmap selected for distribution system is as shown in Figure 3.
In the same five-year period, the deployment in distribution systems will go through three stages: the piloting stage, the initial deployment stage, and the expanded deployment stage with continued enhancement/evolvement beyond the five-year period.

ComEd transmission grid synchrophasor systems deployment: ComEd first implemented PMUs as a pilot project in conjunction with the DOE ARRA along with PJM and other PJM member companies. In 2015, ComEd decided to expand the initial pilot project into a full-scale deployment. Using the roadmap described earlier to justify the costs and to provide the overall architecture, ComEd initiated projects to build the IT infrastructure necessary for a large PMU deployment while also budgeting for 5 years of PMU deployments. The planning process for transmission projects has been updated to include PMUs as part of other reinforcement projects.

To account for future cyber security requirements and to separate real-time functions from engineering applications, ComEd’s IT infrastructure is divided into two subsystems as shown in Figure 4. The first, WASAS, or the Wide Area Situational Awareness System, is intended to support real-time control-room applications as well as secure, CIP compliant communications to the EMS and PJM. The WASAS system is upgradable to meet future CIP requirements as they arise. All synchrophasor data coming from transmission PMUs is sent directly to WASAS.
The second system, WAMS, or the Wide Area Measurement System, supports engineering and synchrophasor data analytics applications and long-term storage. Data and applications used for off-line and after-the-fact analysis have different security requirements than do real-time data and tools, so it makes sense to separate these functions to maintain security requirements where necessary and ease-of-use and accessibility where possible. Distribution synchrophasors have different cyber security requirements than transmission PMUs for data access and security in the field, so the distribution PMUs send their data to WAMS. WASAS forwards transmission PMU data to WAMS for use in engineering analysis and for long term storage.

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