Paving the Way to the 21st Century Smart Grid at Seattle City Light

By Michael Pesin, Seattle City Light

Seattle City Light (SCL), one of the nation’s largest municipal electric utilities, was established more than a century ago. Like many other utilities, SCL has been historically adverse to any significant technological changes. Today, many system components are simply obsolete and no longer supported. A municipal utility must walk the delicate path of educating the city council—and the customers who elect them—to the benefits of maintaining a strong utility infrastructure, as well as explaining the higher overall costs that can be accrued should the infrastructure be allowed to crumble.

With NERC CIP compliance as a major influencer, SCL’s Smart Grid Development Team created a new IP-based architecture that would provide the flexibility and future-proofing necessary to enable SCL to make a cost-effective investment in an intelligent upgrade that would bring the power system into the 21st century. This technology lays the groundwork for the utility’s smart grid initiative that will support growth and evolving technology for many years to come.

SCL’s smart grid vision includes customer end systems, distributed energy resources, energy delivery system, substation system and integration with existing hydro generation (see Figure 1). It is important to note that smart grid is not defined by what technologies it incorporates but rather by what it can do. While there is a set of enabling technologies, each utility will have its own portfolio of systems and technologies based on the unique factors that define the utility. SCL’s smart grid will not emerge from a single rollout of a revolutionary technology but from strategic planning and initiatives all aimed at a long-term vision.

SCL has a holistic approach to its smart grid design where all systems and components support and take advantage of each other, resulting in benefits an order of magnitude greater than those of the individual systems. At the heart of the project is the smart substation, a critical component of the smart grid plan.


Smart Substation Project


The smart substation is the foundation of SCL’s energy delivery system. Its deployment presents a fundamental change not only to the substation control system design, but also to the way the utility will operate in the future. SCL chose Shoreline Station for its smart substation pilot project, which is expected to be completed early in 2011.

The new architecture inserts several layers of intelligence into the substation with an evolutionary process that replaces the simple supervisory control and data acquisition (SCADA) system of the ’80s. By upgrading to an IP-based system now, SCL believes that it will be positioned to take advantage of future standards-based technology advances and evolving regulations.

In the pilot project, the centralized RTU-based substation SCADA system is replaced with a distributed substation control architecture with IP-based communications riding on the SONET backbone. It offers additional information and flexibility, while providing protection for a critical cyber asset. The new architecture incorporates a substation server that consists of a SEL3354 substation computer running Subnet Solutions’ Substation Server and Substation Explorer. Substation local area networks (SubLANs) are enabled by GarrettCom Magnum 6K managed switches and Magnum edge switches connected to a new layer of intelligent electronic devices (IEDs), from a variety of vendors, that interface with substation equipment. The new architecture supports a dramatic expansion of information available to relay to the utility’s enterprise and control center locations.

The substation server acts as a data concentrator, allowing SCL to segregate data based on purpose and functionality. The beauty of the server-based substation architecture is that it allows integration of practically any device with communication capabilities (i.e., an IED) into the substation control system. SCL’s preferred communication protocol is DNP3.0, and IEC61850 is being considered. In addition, SCL can add additional protocols to the substation server in the future, should the need arise.


Integrating Smart Substations with Enhanced DA


The substation server communicates with control devices located along the distribution feeders outside the substation fence. This allows integration of the feeder devices into the SCL control system and enables data collection and management to present information to appropriate operational and IT systems. Another SCL smart grid project will deploy a number of the controllable motor-operated disconnects that will be a part of distribution automation (DA): fault location, isolation and a service restoration (FLISR) scheme. Data will be sent back through the Substation Server for integration with the automation server, distribution management system, or any other appropriate application or database.

As the architecture evolves, SCL sees IP as a critical transport mechanism. The new system will accommodate separate data paths for operational data, non-operational data, and remote access (see Figure 2). A separate IP network will support video and other physical security applications. The IP-based architecture allows for very flexible data management over the communication network; each type of data can be sent to the system that needs it. The operational data can be sent to the EMS and the non-operational data can be sent to other enterprise systems such as asset management and the engineering data warehouse.

Cyber security must be integrated along with the communications system to mitigate the risk of a cyber attack—and to comply with NERC CIP regulations. SCL is currently considering software that will provide secure access management to ensure cyber security and NERC CIP compliance for remote access. The right software will provide the flexibility to move into future compliance requirements.

Video surveillance for utilities is an emerging field and special requirements should be considered for these systems. Requirements should include: performance, bandwidth utilization efficiency, and ability to function in electrical substation environment. The smart substation project uses an integrated CCTV system for both security and equipment monitoring. In addition, SCL plans to integrate thermal imaging cameras in its substation CCTV system. With correct video analytics tools, thermal imaging can aid in preventing equipment failure by detecting abnormal temperatures or an unexpectedly high rate of temperature changes. Since video can be a bandwidth-intensive application, video data streams will have a dedicated communication channel. The dedicated channel will help to avoid any potential performance issues as well as enhancing cyber security.

Implementation of the smart grid architecture will transform SCL into to a modern 21st century utility that will be well positioned to accommodate many challenges facing the utility industry today and in the future. Its smart substation project is at the foundation level for deployment of that architecture. SCL is implementing a fundamental change, not only in the technology being used, but also in the way the utility will operate in the future. In parallel with all the technological improvements, SCL is redesigning its organizational business processes. Technology alone will not bring the utility into the 21st century. Everyone in the organization has to understand and accept these changes. Engaging all stakeholders in the business process redesign at the very early stages of any smart grid planning is vital for success of the project.

Pesin is the chief technology advisor and smart grid architect for Seattle City Light and is actively involved in many industry organizations. He has over 25 years of experience in the electric utility industry and is a nationally recognized expert in smart grid and utility automation technologies. He can be reached at


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