Robots & Sensors, Part II


The benefits of utility automation

Last month, we discussed utility technologies for monitoring, data collection, and remote-control technologies, such as AMI (Advanced Metering Infrastructure) and SCADA (Supervisory Control and
Data Acquisition). This month, we’ll dive deeper by looking into utility automation––or the ability of the system to respond to an event without any direct human input!

There are many different aspects of utility automation, including data and software integration, disconnects and reconnects, and asset control. Automation technologies such as reclosers have been around for decades, but more digital technologies are entering the market, offering greater functionality for electric utilities. In this article, we’ll focus primarily on one part of asset control––smart feeder switching (SFS).

The Benefits of Utility Automation and SFS

There are two main benefits of SFS for electric utilities:

1. Automatic service restoration to non-faulted sections after a permanent fault
2. Dynamic reconfiguration of the distribution network to prevent overloading, minimize outage risks, and achieve load balancing

What this means in plain English: SFS helps bring back power faster after an outage and makes sure it’s done in a safe way.

How Does SFS Work?

There are many technologies that fit under the SFS umbrella, but generally there are three core technologies deployed in the following order:

1. Switch automation
2. Recloser automation
3. Pulse closing

Switch Automation

This technology is great for members who can be served by two or more sources. For example, assume a university is connected by two power lines (each of these lines is referred to as a feeder) from a substation, and a tree falls on the primary feeder powering the university. The system will sense that a fault has occurred and stop sending power through the damaged feeder. With automation, the system will attempt to route power through the backup feeder instead. This can happen so fast that the university may not even notice that a fault occurred on the system.

Recloser Automation

There are many different causes of faults in electrical systems, including lightning, ice, trees, animals, equipment failure, and others. While some faults are “permanent” (a pole or line has been damaged and requires physical repair), others are “temporary” (an animal touches two phases and falls off).

A temporary fault typically does not damage equipment but will still cause a feeder to momentarily lose power. This is where the automatic recloser comes in. After the circuit is opened (halting the flow of power), the automatic recloser will attempt to restore power after a few moments. If the fault is temporary and has cleared, service will be restored with the member noticing only a brief pause in service. If the fault is permanent, the recloser will re-open, shutting down power on that feeder.

Pulse Closing Pulse closing complements reclosers by allowing the system to send out a limited pulse of energy to check for unresolved faults. The purpose is to minimize stress on electrical equipment. Without this technology, every time a recloser closes onto a faulted circuit, a surge of electricity can flow onto the circuit, resulting in equipment damage over time.

Together, these technologies help support the core mission of electric cooperatives to provide safe, reliable, and affordable electricity to their members.

Thomas Kirk is an associate analyst of distributed energy resources for the Arlington, Va.-based National Rural Electric Cooperative Association.