Seminar Report OnDigital Power Line Carrier Communication

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Need of PLCC

To cope up with ever increasing size of power grid

Need for economic and reliable means of intercommunication between various generating station, substation and control room

Avoid dependence of busy telephone lines

Power Line Carrier Communication

Voice signal modulated on carrier frequency and transmitted on power line

No need for lying separate cable for transmission Integrates transmission of voice and data

through same line Allows flow of information through same cording

which supplies electrical power

Digital PLCC-The Challenges ahead

Two biggest problems-

1)Excessive Noise Level

2) Cable Attenuation

Excessive Noise Level Noise and disturbance includes-over voltages,

under voltages, frequency variation and so on. Most harmful noise for PLCC is that superimposed

on power lines Switching device such as light dimmers, induction

motors and television cause such superimposed noise.

Avoid noise superimposition “Frequency Hoping”

For PLCC to operate reliably it must be able to avoid, or cope up with different type of noise encountered which exist at different frequencies at unpredictable times

FREQUENCY HOPING-

It is a spread spectrum communication technique meaning that the total available spectrum is split up into smaller sections so as to be better utilized.

Signal Attenuation

Signal attenuation in power line is often great and unpredictable measured up to 100db /km.

As devices connected and disconnected from power network characteristics changes drastically

This makes coupling a signal to power network difficult.

PLC Regulations

Private-user communications must occur in the bandwidth 95-150kHz.

Within this bandwidth, the section from 125-140kHz is reserved for devices that use unique addressing schemes. Such schemes avoid possible interference from neighboring PLCC devices.

PLCC devices should operate at a maximum transmitted power of 500mW. This limitation is for many reasons, some chiefly being so as to avoid possible radio-frequency interference problems, and neighboring device interference

Applications Internet access Telephony AMR( automated meter readings) Home automation Home security Video conferencing

Advantages

The electric grids are modern, well maintained, and far superior to any of the wired communications networks.

There are more electrical customers than telephone, cable, and other wired communications customers together.

The backbone of the Internet as well as the long distance telephone lines are all fiber optic cables which can carry a signal for only 20 miles, without regeneration, coaxial cable 15 miles and copper telephone wire 5 miles. Signals over the power grid can travel more than 2000 miles without regeneration.

The analog spread spectrum waves have much greater bandwidths or carrying capacity than the digital switched systems.

Another inherent advantage to the Digital Power line model is the fact that it works well over the existing electric power infrastructure. Only the substation server equipment and customer conditioning/service units need to be installed in order to establish a Digital Power line network.

New technology in PLC

PLC has a number of new applications as – Broadband PLC Microwave Technology Frequency conditioned power networking

Broadband PLC

Developed a low cost reliable means of transmitting data, voice and video at high speeds using the infrastructure of electrical power grids and existing utility providers

Electrical power grid is most widespread, maintained worldwide network which provide economical broadband and LAN to every customer that has an electrical outlet

Microwave Technology

Used to pull data through magnetic field created by AC flowing through electrical power

Modulating signals onto magnetic field allow to transmit signal through transformer over high voltage electrical transmission and distribution lines at speed up to 2.5 GB per second

Microwave signals propagated onto mag.flux field can travel up to 2000 miles without regeneration. This allows the electrical grid to carry these communication services at near light speed

Frequency Conditioned Power Networking

Send over a billion bit of data per second over electrical power lines

It breaks the signals into multiple streams, each of which is pulled across the magnetic field in power grid.

Special receivers combine mini streams of data back into original data configuration.

Why Power Lines For Internet??

Offers right balance of cost, convenience and speed

It gives high speed internet access through electrical networks

Lower costs are achieved because the service is implemented on standard electrical lines and is already connected to almost all residence and business through electrical lines

It speed would be 1Mbps, 20 times faster then a standard modem connection

No need for bulky apparatus associated with wireless access.

Will Electrical line replace phone lines?

New power line technology would provide data at almost 10 times the speed of fastest connections currently available to home users

The new rate would be 1 Mbps The flat rate price of most customer is 20 to 30

pound a month but the tap card cost nearly 150 to 200 pound per month.

Conclusion

Tests in PLC have been carried out in 20 countries in around 1500 residences. The mapping of results has been extremely positive and forecasts a great demand for the system

Digital power technology is definitely an exciting alternative to connect internet via phone and modem. Though this technology is not commercially available yet, it should be available over other broadband technologies due to relatively low cost of its local loop. Moreover, its high speed will provide internet access, local phone, and long distance service to customers