When it comes to modernizing the nation’s vast electrical grid, the discussion often centers around hardware and technology: How much can “smart meters” save us? What problems can a common communications platform prevent? How do we integrate wind and solar? But one of the most basic challenges has little to do with technology and a lot to do with the process used to upgrade. This lesson recently received a practical demonstration in Phoenix.

In recent years, equipment failures and employee miscommunication have been responsible for the catastrophic loss of transformers in the Phoenix area. Preventing calamities like these is of paramount importance to the area’s power district, Salt River Project (SRP). When SRP chose to integrate dozens of intelligent electronic devices (IEDs) at its Browning 500/230kV station early in 2006, they wanted a system that would be more than just efficient and cost effective. They wanted a system that would also warn operators of problems and potential disasters.

To meet that challenge, John Blevins, SRP’s manager of Power Quality Services, brought in consultants from  the Electric Power Research Institute (EPRI) IntelliGrid^SM program, an international consortium that seeks to develop the infrastructures for the next generation of energy delivery. Blevins had been on the IntelliGrid Steering Committee, and SRP had been one of the consortium’s original funders. With IntelliGrid's guidance, SRP took on a new, rigorous approach to identifying and documenting project requirements. They developed “use cases,” a practice common in the software industry.

IntelliGrid consultants are adapting these techniques to the electric power industry. Use cases describe tasks that end users will accomplish using the system, and includes the responses of the system to the end user's actions. Team members from affected parts of the company participate. The use cases are then documented and reviewed to ensure all stakeholder needs have been captured. The documents readily translate into functional requirements (what a system must do), although more work may be needed to specify nonfunctional ones (what a system must be).

The use case approach promises significant cost reductions. Although they may cost more in the beginning, use cases can save time and money later. For one thing, they reduce the risk of rework. For another, they create documentation that helps pinpoint the best vendors and equipment. Furthermore, they lead to integrated, open standards-based systems that are cheaper to buy and easier to maintain.

In addition to cost savings, use cases record institutional knowledge and provide a resource for future parallel projects.

SRP modified the proposed IntelliGrid approach to fit its own people and culture. They avoided the Unified Modeling Language that is common to the software industry. Instead, they documented cases using tables familiar to their engineers. They also broke with IntelliGrid’s recommended IEC 61850 communications protocol and went with the DNP3 system they had been using.

Although hard evidence of monetary benefits will not be apparent until more time has passed, use cases have already proved to be an effective way to get experts and stakeholders to start thinking about the processes they already have and the functions they need to develop.

Click below to download a full case study that provides more details about SRP’s application of the IntelliGrid use case methodology. You’ll also gain insights into the tasks involved in integrating a substation’s IEDs with a common communications platform – work that lies ahead for virtually any utility that intends to modernize a distribution network.

   SGN Salt River Project case study (PDF)

   IntelliGrid Web site