Current PLC Network Market
Currently, electric distribution
networks have greater coverage than telephone and
cable TV networks, reaching 95% of households. In
other words, through the PLC system most people will
have the possibility of connecting to the Internet.
Since the services of these other types of networks
are already available in offices and industries, the
markets expected to benefit most are residential
areas and small and middle-sized businesses.
It should be born in mind that
despite its smaller coverage, the existing telephone
network reaches all social sectors that can afford
service. Supply of low-cost VoIP services would thus
be competitive in lower-income sectors, which would
cease to be customers of the local phone company.
High and very diverse
expectations have been generated around PLC
technology. Some emphasize the social value of
exploiting this technology (pursuing equality in
access to information technologies and promoting
human development), while others are commercial.
The promise of coverage for
economically non-viable geographical areas with
highly scattered users or difficult access is the
calling card of this technology with respect to
social ends. (This concept applies to users with LV
supply, since transmission to the distribution
transformer at MV is not competitive compared to
DSL, as explained later). The advantages of this
technology are extensive, which encourages its
development..
General operation principles
PLC
technology is simply a set of transmission elements
and systems which, based on a regular power
transport and distribution infrastructure, can offer
customers the regular services offered by
telecommunications operators.
It
is possible to attain speeds between 1 and 1.5 Mbps
per user. This makes it possible to offer Internet,
high-speed data transmission and even IP telephony
services.
All
that is needed is to condition the electrical
distribution infrastructure so it can transmit two
kinds of signals simultaneously without either of
them being affected: a low-frequency signal (50 to
60 Hz) to distribute power and a high-frequency
signal (1-Mhz band) to transmit data, both of them
flowing through a copper pair.
The
new network, now configured and conditioned, is
called High Frequency Conditioned Power Network (HFCPN),
allowing the simultaneous transmission of power and
data.
Servers are installed in electrical substations (or
local transformers), which are usually connected to
the Internet through fiber optics. The network-level
protocol is IP.
The
power distribution network is basically composed of
three parts or sections: low, medium and high
voltage. Only the low-voltage section is used,
something known in telephony as the last mile, or
the section that connects households to the power
substations (equivalent to the local switch in
telephony).
Figure. Structure of elements to provide Internet
over the power network.
Operation Scenarios
PLC (Power Line Communications),
also known as Power Line Telecommunication (PLT) or
Broadband over Powerline (BPL), is the technology
that makes it possible to transmit video, voice and
data over the power networks. It should also be
understood that the existing cabling inside each
residence or office is part of the power network.
PLC technology offers the
creation of home networks and access to broadband
Internet using the existing power cabling
infrastructure, without the need to install a new
one.
This infrastructure can be
divided into two general scenarios. One uses the
existing power cabling in a building, home or office
to set up internal communications (In-home), while
the other uses the low- and medium-voltage
distribution lines of a power utility to offer
broadband Internet service (Access) through them.
Before introducing concepts
related to PLC, it is useful to provide a brief
description of what is known as power distribution
networks, which are divided into high-, medium- and
low-voltage networks.
High-voltage power lines make up
a transport network that carries power from the
generators to the consumption centers (population
centers and industries). Most high-voltage power
lines are aerial, and the voltage values handled in
these sections are in the neighborhood of hundreds
of kilovolts, since these high voltages allow energy
to be transported more efficiently. At consumption
sites, such as cities, there are usually large
transformation centers that convert this electrical
power into lower voltage values, giving rise to a
second network the medium-voltage power network ,
which usually handles values between 10 and 50
kilovolts.
Finally, a new transformation
takes place so that households can be provided with
electric power. Depending on the country, there are
facilities in population centers, in buildings or
underground, known as transformation centers, where
power is transformed to 110/220 volts the voltages
typically used in households. This is what is known
as low voltage.
In turn, the power networks can
be divided conceptually into several sections from
the power plant to the subscriber, as follows:
- A first medium-voltage section, between 15 and
50 Kv, from the power generator to the first
step-up transformer
- A transport or high-voltage section, between
220 and 400 Kv, that carries power to the
transport substation
- A medium-voltage section 66 to 133 Kv
between the transport substation and the
distribution substation
- Another medium-voltage section between 10 and
50 kV, from the distribution substation to the
distribution center
- Finally, a low-voltage power line between
110 and 400 volts that distributes power inside
urban centers for domestic, commercial and
industrial use
Currently, the application zone for PLC
technology is in the last two sections of the power
network, namely the medium- and low-voltage
sections.
This
text is from the technical notebook on Aspects of
PLC of PCC.I Coordinator: Ms.
Josefina Cano |