Power-line communication
However, with the introduction of advanced networking technologies, there has been a push for utility and service providers to find cost-effective and high-performance solutions.
The possibility of using powerlines as a universal medium to transmit not just electricity or control signals, but also high-speed data and multimedia, is now under investigation.
A number of difficult technical problems are common between wireless and power-line communication, notably those of spread spectrum radio signals operating in a crowded environment.
Utility companies use special coupling capacitors to connect radio transmitters and receivers to the AC power-carrying conductors.
Filtering devices are applied at substations to prevent the carrier frequency current from being bypassed through the station apparatus and to ensure that distant faults do not affect the isolated segments of the PLC system.
They consist of one or more sections of resonant circuits, which block the high-frequency carrier waves (24–500 kHz) and let power frequency current (50–60 Hz) pass through.
Power-line carrier systems have long been a favorite at many utilities because it allows them to reliably move data over an infrastructure that they control.
In a two-way system (supporting both outbound and inbound), commands can be broadcast out from the master station to end devices (meters) – allowing for reconfiguration of the network, or to obtain readings, or to convey messages, etc.
This type of broadcast allows the communication system to simultaneously reach many thousands of devices—all of which are known to have power, and have been previously identified as candidates for load shed.
Typically home-control power-line communication devices operate by modulating in a carrier wave of between 20 and 200 kHz into the household wiring at the transmitter.
Since the carrier signal may propagate to nearby homes (or apartments) on the same distribution system, these control schemes have a house address that designates the owner.
French electric power Électricité de France (EDF) prototyped and standardized a system called spread frequency shift keying or S-FSK.
In the 1970s, the Tokyo Electric Power Company ran experiments that reported successful bi-directional operation with several hundred units.
(It is common for dirty insulators to arc at the highest point of the voltage, and thus generate a wide-band burst of noise.)
The drive is to produce a reliable system that is cheap enough to be widely installed and able to compete cost effectively with wireless solutions.
One natural application of narrow-band power-line communication is the control and telemetry of electrical equipment such as meters, switches, heaters and domestic appliances.
Possible utility-side applications include automatic meter reading (AMR), dynamic tariff control, load management, load profile recording, credit control, pre-payment, remote connection, fraud detection and network management,[13] and could be extended to include gas and water.
OSGP follows a modern, structured approach based on the OSI protocol model to meet the evolving challenges of the smart grid.
At the OSGP application layer, ETSI TS 104 001 provides a table-oriented data storage based, in part, on the ANSI C12.19 / MC12.19 / 2012 / IEEE Std 1377 standards for Utility Industry End Device Data Tables and ANSI C12.18 / MC12.18 / IEEE Std 1701, for its services and payload encapsulation.
[17] More modern systems use OFDM to send data at faster bit rates without causing radio frequency interference.
In the protocol, 6loWPAN has been chosen to adapt IPv6 an internet network layer to constrained environments which is Power line communications.
In December 2011, G3 PLC technology was recognized as an international standard at ITU in Geneva where it is referenced as G.9903,[21] Narrowband orthogonal frequency division multiplexing power line communication transceivers for G3-PLC networks.
Broadband over power line (BPL) is a system to transmit two-way data over existing AC MV (medium voltage) electrical distribution wiring, between transformers, and AC LV (low voltage) wiring between transformer and customer outlets (typically 100 to 240 V).
In North America, it is used in some places (Washington Island, WI, for instance) but is more generally used by electric distribution utilities for smart meters and load management.
Even higher information rate transmissions over power line use RF through microwave frequencies transmitted via a transverse mode surface wave propagation mechanism that requires only a single conductor.
While these may interfere with radio astronomy[22] when used outdoors, the advantages of speeds competitive with fiber optic cables without new wiring are likely to outweigh that.
[23] Multiple Wi-Fi channels with simultaneous analog television in the 2.4 and 5.0 GHz unlicensed bands have been demonstrated operating over a single medium voltage line conductor.
Also since it is not restricted to below 80 MHz, as is the case for high-frequency BPL, these systems can avoid the interference issues associated with use of shared spectrum with other licensed or unlicensed services.
Additionally, the BPL (Broadband over Power Line) systems may experience interference from the radio signals produced by the PLC wiring.
[3] For home networks relying on powerline communication technology, how to deal with electrical noise injected into the system from standard household appliances remains the largest challenge.
