Power Line Communication

Ghulam Yasin

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

PLC Technologies

Three network levels High voltage (110–380 kV) Medium voltage (10–30 kV) Low voltage (230/400 V, in the USA 110 V)

Modulation and error correction OFDM CDMA

Power Line Carrier - Overview

Data Packets are sent over the existing power lines Power Line is the transmission medium No need for radio transmitters or telephone

connections for each meter Inherent on-line system design capability

Power Line Carrier TechnologyHow does it work?

Current frequency is used as the carrier Information is sent in packets modulated on

the current frequency (Carrier Frequency) by the remote transmitter

Signals demodulated at the receiver end and information is then decoded.

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.

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.

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

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 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

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

Power Line Carrier TechnologyAdvantages

No need for additional expensive communication medium Existing Power Line is the communication medium

System can be on-line, and can alert the utility of power problems if no signal is detected from the customer end Using this technique of communication the data can

be transferred over the existing LT Power lines. Encryption is provided for, to ensure the data

accuracy, integrity and security

Advantages 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.

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.

Power Line Carrier TechnologyDisadvantages – (Traditionally)

Transmitter power demands are high to increase the signal travel distance

Transmitters are large due to large power requirements

Signals may not travel well through transformers or capacitors

Signals easily affected by noise on the lines Applications are limited to short distances due to

the above factors

PLCC Based AMR Network Architecture for LT PLCC Based AMR Network Architecture for LT Commercial & Domestic ConsumersCommercial & Domestic Consumers

DCU BCS

RURU RU RU

RURU RU RU

HT LINE

LT LINE

PLCCData FlowFrom DCU

To DCU

PSTN/GSM/GPRS CDMA

Primary ComponentsPrimary Components

• 1 phase and 3 phase Direct Connected / CT operated Multi-function Energy Meter with in-built PLCC Modem.

• Data Concentrator Unit (DCU) with inbuilt PLCC Modem for communication with Meters & GSM /GPRS/ PSTN Modem communicating with the central station.

• Base Computer software (BCS) installed at Master Station Server with GSM/GPRS/ PSTN Modem.

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