Tài liệu Powerline Communications Systems

Historical Overview
PowerLine Communications is the usage of electrical power supply networks for communications
purposes. In this case, electrical distribution grids are additionally used as a
transmission medium for the transfer of various telecommunications services. The main
idea behind PLC is the reduction of cost and expenditure in the realization of new telecommunications
networks.
High- or middle-voltage power supply networks could be used to bridge a longer distance
to avoid building an extra communications network. Low-voltage supply networks
are available worldwide in a very large number of households and can be used for the
realization of PLC access networks to overcome the so-called telecommunications “last
mile”. Powerline communications can also be applied within buildings or houses, where
an internal electrical installation is used for the realization of in-home PLC networks.
The application of electrical supply networks in telecommunications has been known
since the beginning of the twentieth century. The first Carrier Frequency Systems (CFS)
had been operated in high-voltage electrical networks that were able to span distances over
500 km using 10-W signal transmission power [Dost97]. Such systems have been used
for internal communications of electrical utilities and realization of remote measuring
and control tasks. Also, the communications over medium- and low-voltage electrical
networks has been realized. Ripple Carrier Signaling (RCS) systems have been applied to
medium- and low-voltage networks for the realization of load management in electrical
supply systems.
Internal electrical networks have been mostly used for realization of various automation
services. Application of in-home PLC systems makes possible the management of numerous
electrical devices within a building or a private house from a central control position
without the installation of an extra communications network. Typical PLC-based building
automation systems are used for security observance, supervision of heating devices, light
control, and so on