Erich Gunther & Sandy Smith, EnerNex Corp.
The August 14 blackout in the Northeast and Midwest United States and southern Canada served as a clarion call about the need to upgrade the electric power grid. Indeed, the findings of the U.S.-Canada Power Systems Outage Task Force suggested the need for a “smart” grid that can provide prompt diagnosis of problems when they occur and even correct faults and enact corrective measures. The potential promised through the incorporation of microprocessor technologies into utility infrastructure and expanded automation of utility operations and processes has raised the potential for such a self-healing grid.
Recent thinking about how to build the perfect grid has centered on coupling electric power and communication systems while taking advantage of distributed computing to expedite implementation. It is recognized that computing and communication technologies-particularly with the increased utilization of the Internet-pose not only a great opportunity to optimize and enhance the performance of the power system, but also a tremendous challenge. Concerns about securing the grid from cyber attacks, computer viruses and software deficiencies arise with any discussion on incorporating computers with power systems.
Industry and government sector efforts are currently underway to lay the groundwork for the next generation power grid. These efforts focus on the definition, specification and implementation of a design that can then be built to either replace the existing grid or overlay on top of it. The concept of an industry-wide architecture is being widely utilized because of the massive scope and scale of what is necessary to realize a “smart” power grid capable of fixing itself. Indeed, the potential for the supporting data communications and computing technologies is as extensive as the existing power system. The number of intelligent devices supporting a smart grid could easily be in the millions, thus an architecture-level approach enables a view from a height that facilitates data and application sharing among the various stakeholder groups that operate, oversee or receive energy from the power system. Such architecture also holds the potential for adoption by multiple vendors. This will also help identify system or enterprise-level management issues that might not be noticed until after the smart grid is implemented.
A highly visible effort at defining and developing such architecture is being undertaken by the Consortium for Electric Infrastructure to Support a Digital Society (CEIDS)-organized by the Electric Power Research Institute (EPRI) through its Electricity Innovation Institute (E2I) subsidiary-to provide a strategic framework for upgrading the electric power system. The cornerstone of CEIDS is the Integrated Energy and Communications System Architecture (IECSA), which is developing an open, standards-based systems architecture for the data communications and distributed computing infrastructure that enables integrating a wide range of intelligent power system components. IECSA is building on prior industry infrastructure work, incorporating the latest and greatest communications and computing technologies to provide an interoperable/networked foundation for developing data communication networks and smart components to support a grid that is not only self-healing, but also able to support such industry functions as real-time pricing, demand response, energy management and market operations.
The IECSA effort is being conducted in a completely open fashion with a concerted effort to directly involve a wide range of industry stakeholders in the process. The most visible aspect of this philosophy is the project web site (http://www.iecsa.org). This web site contains overview information, interim reports, minutes of meetings and the final deliverables as they are constructed. This unprecedented openness for a project of this type is critical to the project’s success by soliciting feedback from the stakeholders early and often, and then acting upon it to improve the project results.
Another effort being undertaken in the public sector is the GridWise Alliance, which is organized by the U.S. Department of Energy (DOE) and private sector partners. GridWise is a vision of how advanced communications, information and controls technology can transform the nation’s electric system. GridWise is not strictly a research and development effort aimed at achieving this vision, but is more of a vehicle to coordinate activities to leverage these technologies into developing an integrated power system capable of spanning all components and applications from generator to customer appliances. It is encouraging to see such a high degree of cooperation between the IECSA and GridWise activities. The DOE is a member of the CEIDS organization and E2I has recently joined the GridWise alliance. Cooperation and joint optimization of research efforts, standards and policy developments are critical for moving the industry forward at a reasonable pace.
Smart grid architecture comes into play
To best understand the scope that a comprehensive utility communications, command and control architecture must deal with, here is a fictional-but realistic future scenario of how a fully deployed system might operate. The scenario illustrates how a smart grid design can improve the reliability and performance of the overall system from power generation to end-user facilities.
The scenario: It is 15:00:00 CDT near Nashville, Tenn. and heavy thunderstorms roll into the area. The temperature is 99 degrees and the humidity is about the same. A new peak load record will be set today. High winds, heavy downpours and significant lightning accompany the storms. At 15:12:10 CDT, lightning strikes a tower on the Tennessee Valley Authority 500 kV Roane-Wilson line-the major line serving Nashville from the east. This causes a flashover. This is reported in real time via the National Lightning Detection Network and reported automatically on the operator’s SCADA display. The flashover results in the failure of one of the line insulator strings-a permanent fault.
The ensuing fault results in breakers opening at both the Roane and Wilson stations. Due to a protective device configuration problem, the 1100 MW generating plant at Watts-Bar trips off-line. At 15:12:40 CDT, after unsuccessful re-close attempts, the breakers lockout because of the permanent fault. At 15:12:45 CDT, the automatic generation control for the area starts responding to a deficit of generation in the Nashville area because of the line outage and generator trip. Signals are automatically sent to other generators in the area using the newly implemented smart grid to increase local generation. At 15:13:00 CDT, the Emergency Control System (ECS) module of the system determines that there is not enough generation or line capacity to meet the generation deficit. The ECS evaluates the situation and decides that a combination of line reconfiguration, power flow controller operation, load reduction and dispatch of distributed generation resources in the area will make up the deficit. The system updates prices for the next hour for customers on hourly real-time pricing rate structures, sends interrupt signals to selected interruptible rate customers in the affected area and initiates residential load control by sending signals to shut down water heaters and other non-essential loads for that particular time of day.
As generation starts to come on-line and load is reduced, several Flexible AC Transmission System (FACTS) controllers in the area have also been commanded to divert power flow onto the TVA 161 kV lines to help overcome the deficit. On-line power flow, stability and security analysis applications have re-calculated the optimum FACTS configuration.
In an industrial park in the Nashville area, a large, automated plastic bag manufacturing plant on a real-time rate has received the next hour’s prices, which are extremely high because of the line and generator outage. Their energy management system has decided to shut down the plant to save money. Nearby, a semiconductor manufacturing firm has benefited from a temporary reconfiguration of protective devices in the area. When the local ECS determined that a storm was in the area (from National Lightning Detection Network data) the re-closers’ instantaneous trip settings were temporarily restrained on selected feeders serving sensitive loads to minimize momentary interruptions and multiple sags because of multiple re-close attempts. A few more fuses would be sacrificed in residential areas to prevent the storm from disrupting critical industrial loads during the day.
An Internet service provider in the affected area is on a feeder with distributed generation resources sufficient to meet the entire load in that area. When the ECS dispatched the generation, the local substation controller decided to temporarily island itself from the main utility grid to eliminate the impact of voltage sags from the transmission system.
By 15:15:00 CDT, the load/gen-eration imbalance had been fully satisfied and a new, stable system configuration had been achieved. As the storm moved through the area, small, local configuration optimizations were performed.
The storm dissipates by 15:45:00 CDT and as local ECS controllers sense this through input from various distributed measurement devices, they begin restoring protective device settings back to normal. As work crews complete repairs on the transmission line a few hours later-restoring service-and the Watts-Bar generator comes back on-line, real-time prices are adjusted accordingly, generation is re-dispatched, line configurations and FACTS controllers revert back to their normal duties and optimal configurations and islanded systems are re-synched to the grid.
By the next morning, several applications with access to the ECS database have automatically prepared reports on how the system performed, the total cost of the storm including incremental generation costs, repair costs, etc. Power quality and reliability performance reports were also prepared for engineering and marketing personnel. Any system anomalies encountered during the storm were automatically analyzed with a maintenance plan prepared and e-mailed to appropriate personnel.
The smart grid has prevented a wide-area outage because of the generation deficit, has optimized the configuration of local distribution systems to deal with the storm and has minimized specific load center disruptions.
Specifying and building the “grid of the future” applies the latest methods from the systems engineering community, but still it is not an academic exercise. These efforts reflect a serious effort to address looming industry issues related to the design, deployment and management of intelligent equipment for the existing and emerging power/energy industry. For all the potential benefits resulting from increased integration of data communication and distributed computing technologies, there is also a “dark side” that must be addressed up front. The lack of a concerted, deliberate technical approach to the deployment of these technologies by the energy industry risks misspent capital and poor systems integration, as well as more potentially serious consequences from security threats to the power delivery system infrastructure.
The IECSA project is scheduled for completion during the summer of 2004. The result will be a four-volume set of documentation describing the architecture, the requirements upon which it is based, the methodology used to arrive at the architecture and the guidelines for its application (with examples). Several organizations are presently utilizing interim information, methods and tools that have been emerging from the IECSA project to assist in their own automation and communications improvement efforts. The lessons learned from these early adopters are being fed back into the final deliverable preparation process.
In addition to the documentation, various tools and databases will be made available along with a “navigable model” of the reference architecture. This combination will provide system planners, designers and implementers with a comprehensive set of tools and a methodology to build the “grid of the future.”
For more information, please visit the following Web sites: www.iecsa.org, www.e2i.org, www.gridwise.org.
Gunther is a co-founder and chief technology officer and Smith is manager of marketing and business development for EnerNex Corporation.