The fiber-optic current sensor has been integrated into a 420-kV power circuit breaker at a digital substation in Sweden.
The world has gone digital and that includes the electricity industry. It is hard to remember the time when relays were simple electromechanical devices without firmware, communications interfaces or multifunctionality. Providing electricity has always been challenging, but new technologies increased the complexity of that challenge when moving from the 20th century to the 21st century. The industry had to bridge the gap between aging analog devices and digital technologies.
Today, there is not a single component in a substation that has not been enhanced, enriched or augmented by some form of embedded digital technology, making them operate better at higher ratings with more reliability than ever before. However, the challenge now is integrating all of these elements into a totally digital substation and making it work in a demanding environment.
Several issues are pushing the digitalization of the electrical substation. The grid is operating mainly at maximum capacity in much of the developed world as customers demand more power and better power quality. Therefore, when a fault takes place, it must be cleared as quickly as possible, which is where modern digital technology offers so many benefits. On the customer side of the meter, digital technology is being integrated into the Internet of Things (IoT). In a nutshell, IoT is a network of devices, buildings, vehicles and just about every other type of physical object one can think of equipped with sensors, connected by networks, and monitored and controlled by computer-based systems.
Smart Is Not New
With IoT, people can check the security of their homes from hundreds of miles, or kilometers, away. Home thermostats can be adjusted from any location by pulling up an app on a smartphone. Luggage can be tracked with another app when the airline says it cannot locate a missing suitcase. Cars even e-mail their owners when they need maintenance. And IoT has taken this connectivity to a level of being able to add sensors on people and monitor them with wired workout clothes and devices like a Fitbit fitness tracker.
This level of connectivity also has found its way into substations and switching stations, as utilities integrate more equipment with interconnectivity capability. The digital substation concept has been grabbing a lot of traction with utilities around the world, but one should know digital technology is not a new concept to the electric power industry. Utilities have been digitizing their facilities in one form or another for decades. In the period after World War II, transmission systems experienced an unparalleled growth period as demand for electricity increased. Visionaries saw a need for new technologies to play a bigger role in how the grid was controlled and managed.
Long before there was a smart grid, the electric power industry had a stratagem of an all-knowing grid with technology-enabled substations networked into a communicating transmission and distribution grid. The nomenclature may have been different, but the idea had smart grid written all over it; the technology just needed time to develop. The industry deployed supervisory control and data acquisition (SCADA) and then remote terminal units (RTUs) were introduced. These were followed by the introduction of micro-processor-based relays for control and protection systems.
Technology moved forward and communications interfaces were integrated directly into the microprocessor-based relays. Advancements in the microprocessor’s firmware and software brought about multifunctional microprocessor-based relays that communicated directly with RTUs and gateways.
All of these innovations ramped up the complicatedness, but they also increased system performance enormously. During about the same time frame, vendors began incorporating intelligent electronic device (IED) technology into the electrical apparatus and components found throughout the substation, including the switchyard. As a result, the industry experienced a transformation more far-reaching than any in the past. Not only was the industry exploiting digital technology, but it was setting the stage for incorporating IoT technology into the grid.