Introduction: Governments and power companies across the world have recognized that the traditional grid, which has not significantly changed in 100 years, must be replaced by more efficient, flexible and intelligent energy-distribution networks, called smart grid. These are digitally monitored, self-healing energy systems that deliver electricity or gas from generation sources, including distributed renewable sources, to points of consumption. They optimize power delivery and facilitate two-way communication across the grid, enabling end-user energy management, minimizing power disruptions and transporting only the required amount of power. The result is lower cost to the utility and customer, more reliable power, and reduced carbon emissions.
Power lines reach all units that require “power” from a direct connection to a plug. Hence, power lines are a cheap communication medium always available to interconnect units without adding unnecessary and expensive cables or radio frequency systems.
A narrowband communication over power lines is sufficient for simple information exchange such as measure, command to actuators, check system, and so on, and allows a wide number of applications both in outdoor and indoor environments. For example, utilities can use the outdoor network for remote street lighting control and monitoring or for Automatic Meter Reading (AMR) and Management (AMM), simultaneously providing many client services like power consumption control and tariff selection. In the home, the indoor electrical grid can be used to connect home appliances realizing home or building automation, security and safety systems, temperature and lighting fixtures control. To make this possible, a Power Line Modem (PLM) is necessary. Like ordinary modems, a modem suitable for use over power lines is able to convert a binary data stream into a sequence of signals with predefined characteristics (frequencies, levels) and vice versa converts them back into the binary data stream, completing the modulation / demodulation process. They must be able to convey the modulated signals over the power line and detect arriving signals, which comprises the transmission/receiving process.
As mentioned briefly above, one of the first applications was the Automatic Meter Reader, or AMR. Traditional electromechanical meters are based on a technology that is unsuitable for further significant development. Electronic meters offer many significant advantages for the utility companies and consumers, including lower costs for manufacturing, calibration and maintenance, greater accuracy and, most important, the ability to provide the consumer with detailed information based on their own real consumption and the electricity supplier with punctual service quality data.
The AMR evolution is the smart meter, a key building block of the smart grid. The benefits of the Smart Meter to both the electric utility and customers are concrete: consumers can more accurately monitor and control their consumption (for example, by using appliances such as washing machines, dishwashers or electric showers at times when the cost is lowest) and energy providers can generate and distribute power more efficiently.