Utilities are Expanding as We are Building Out Our Massive Transmission Network and maintaining our substations. In the United States, PJM Interconnection (Norristown, Pennsylvania) operates in 13 states with an overview of approximately 3660 substations, American Electric Power (Columbus, Ohio) operates in 11 states with more than 4800 substations and Duke Energy (Charlotte, North Carolina) operates in 17 states with roughly 6000 substations.

Worldwide, substations range from extremely old to ultramodern. The control technology follows the same chronicle running from antique electromechanical relays to powerful microprocessors. But no matter the age, each substation requires station checks. These checks can be the monthly manual variety, which require personnel to visit the station, or can rely on substation automation technology. Whichever method is used, utilities track the health of each component of the substation. But doing so requires tapping into an increasingly sophisticated and intelligent network.

LOCALIZED INTELLIGENCE

The traditional approach to energy management systems consists of a centralized command and control center, with an operator who monitors substations as a group and makes grid-reliability decisions accordingly. This paradigm is shifting toward a more decentralized, distributed analysis and control infrastructure.

Dr. Jay Giri, the director of power system technology and strategic initiatives for AREVA T&D Inc. (Philadelphia, Pennsylvania, U.S.), explains, “The recent technological trend is toward increased deployment of intelligence and analysis capabilities at the substation level, thereby empowering more grid-reliability decision making at the substation level.”

AREVA has been deploying mini supervisory control and data acquisition (SCADA) systems at substations to decentralize control and to allow for prompt local decision making. “The ensuing trend is to build control systems for a group (or pool) of neighboring substations,” states Giri. “Real-time data can then be exchanged between these substations and analyzed, and decisions made to protect the grid in their geographical region. These actions are then reported to the central control center for portrayal in the wide area monitoring screens.”

The Electric Power Research Institute (EPRI) reports that an integrated approach to substation information technology consolidates the hardware and software needed for equipment monitoring into a single substation-based data acquisition, analysis, display and alarm system. But how many utilities are really taking advantage of what the technology has to offer?

Typically, each utility moves along at its own pace, and technology is accepted one step at a time. Transformer monitoring systems are installed to give operations the ability to load large power transformers in real time, but access to operational and nonoperational transformers is limited. Microprocessor-based control and protection systems with capabilities of fault recording, sequence-of-events recording and SCADA abilities are installed only in a few substations, with many of the intelligent substations remaining isolated islands rather than parts of an intelligent network. But times are changing.

TIME GAINED, MONEY SAVED

An intelligent network of substations is not only operationally efficient, it is more labor efficient and even fuel efficient. Tony Pink, general manager of Dynamic Ratings Inc. (Pewaukee, Wisconsin, U.S.), calls the new generation of engineers and technicians the “Nintendo generation,” and says, “They are as comfortable with Web-based applications as the boomers were with their slide rules.”

Pink compares today's powerful transformer monitoring systems to Nintendo games. The Web-based monitoring systems provide operational and nonoperational data, and can be interrogated from any Web access point. “This generation grew up with those video games and the Internet,” says Pink. “Today's culture is Web based and instantly accessible, from texting to library databases. Why shouldn't our technology be the same?” This generation is trained to communicate, multi-task and manipulate data with precision and speed to get the information for any question. They take it for granted that information will be at their fingertips.

Why would a technician spend time driving to a substation to read gauges, check the drag arms on a temperature gauge and look at a couple of meters when he can access a month's worth of accurate historical data from a central database? Reducing windshield time is critical when the number of skilled engineers and technicians is limited and the price of vehicle operation is rising exponentially.

Compare the concept of the “negawatt,” a megawatt not generated is a megawatt saved, to the gas scenario, gasoline that is not consumed improves the fuel efficiency of the utility's fleet. Metaphorically, the intelligent substation's mile-per-gallon fuel consumption is quite an improvement over the less-than-intelligent substation requiring getting behind the wheel and driving hours to the station, especially if there are hundreds if not thousands of substations in the system covering a large geographical area.

THE WHOLE IS GREATER THAN THE SUM OF ITS PARTS

After the 2003 blackout, former U.S. Secretary of Energy Bill Richardson compared the North American grid to that of a Third-World country. He was correct in some aspects, but wrong in others. In the developing portions of the world, such as India, Asia and Africa, utilities have recognized the operational and labor efficiencies brought about by fully integrated intelligent substations. In North America, utilities are just beginning to explore this technology.

“Worldwide, there are over 300 substations commissioned and running using IEC-61850-based technologies. Not all of these stations are taking advantage of the technology's full abilities, but that is changing,” reports Alan Grightmire, group vice president of substation automation for ABB Inc. (Zurich, Switzerland). “ABB sees interest growing in implementing intelligent networks consisting of multiple IEC-61850-based substations working together as a collective. Utilities in India are very interested in the benefits of this IEC-61850-based networking.”

Significant advances in software and expert system programs have taken place. Utilities are able to optimize asset utilization (more power transferred over lines) and minimize maintenance costs (a significant portion of controllable costs) with the equipment-condition information they are receiving. As more networking is specified and installed, ABB has seen an increase in the turnkey approach. This assures all parts of the network operate together.

A DATA REFERENCE POINT

Networking a group of intelligent substations produces important data related to the system. By feeding the data into a state estimator, it is possible to develop models for load forecasting, VAR control, available transfer capacity, dynamic line ratings and transient stability. Marketing models also can supply day-ahead projections, power balancing, spot pricing, transmission pricing and ancillary services. In the area of protection and control, it can be used for load shedding, out-of-step protection and apparatus coordination.

The list continues to grow as more utilities deploy the technology, but it has to be accurate and timely when it is delivered to the users. That requires a reference point to be able to establish the sequence of events. Time-tagging has been available from SCADA systems since they first came on the grid, but it isn't sufficient with networked automated substations.

“We need to be using global positioning systems (GPS) for greater accuracy,” says Dr. A.P. Sakis Meliopoulos, a distinguished professor at the Georgia Institute of Technology. “The data has to be accurate to 0.1% with a time precision of 1 msec to be useful in the models. An error in the phase angle of 1 degree translates into 150 MW of capacity in a 50-mile (80-km) 500-kV transmission line.”