Power line communication implementation for
DC applications
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 kilometres),
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
air planes, auto mobiles 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.