Ajinder Singh and Dave Hermann, Texas Instruments -February 03, 2014
Power line communication (PLC) is a communication technology that sends data over existing power cables. This technology can send both power and data between PLC nodes in a half-duplex manner. Combining power and data over the same lines allows PLC technology to eliminate the need for additional wires to interconnect devices. PLC offers a cost-effective communication media for a wide range of applications in environments that otherwise might be too expensive to network. As a communications technology, PLC can be divided into two categories:
- Broadband PLC is appropriate for high-speed broadband network connections such as to the Internet. It generally operates at higher frequencies (1.8–250 MHz), high data rates (up to 100s of Mbps) and is used in shorter-range applications.
- Narrowband PLC is useful for applications requiring narrowband control or low-bandwidth data collection where low cost and high reliability are essential. It generally operates at lower frequencies (3–500 kHz), lower data rates (up to 100s of kbps), and has longer range (up to several kilometers), which can be extended using repeaters.
Depending upon the underlying power line characteristic, PLC can be further classified as PLC over AC power lines and PLC over DC power lines.
Many utilities around the world have chosen narrowband PLC over AC lines for their smart grid projects. By monitoring electricity usage based on time of day and even by device or application, utility companies can provide pricing structures that give consumers incentives to adjust their energy consumption, thus reducing peak-load and avoiding the need to construct new power plants.
The popularity of PLC adoption in smart grid applications has led to significant focus on PLC over AC power lines. However, narrowband PLC over DC lines is also gaining ground in home networking, lighting and solar applications as well as in transportation vehicles (electronic controls in airplanes, automobiles and trains). The use of PLC in these applications reduces wiring complexity, weight, and ultimately cost of communications.
In this article we focus on the use of PLC over DC power lines and present a reference design that can help customers adopt PLC over DC power lines quickly and effectively.
One common question asked by system integrators is how to compare PLC over DC versus low-power wireless technology. While both PLC over DC and low-power wireless do not require new wire installation, with PLC, the connection is maintained even underground, through walls, and around corners. The communication channel is owned by the operator or utility, so the risks of sharing bandwidth are eliminated. PLC has no line-of-sight limitation and is not affected by weather.