A DATA COMMUNICATION NETWORK OVER ELECTRIC POWER DISTRIBUTION NETWORKS

Abstract

The purpose of this thesis was to demonstrate the design and implementation of a complete data network intended for use over electric power distribution ' circuits. Medium-tension lines, as well as the low-tension lines, are used as data

links in the network, thus achieving universal connectivity from the electric utility to all the customers served by the utility. The network is used primarilv in remote reading of the utility counters. However, the network may be used in telecontrol, feeder-automation, load management, and data acquisition from utility sub-stations as well as in remote reading of gas and water counters. The network uses two I different accessing protocols, as well as different modulation techniques, over low-

tension and medium-tension lines; each of which is optimized for operation on i(s particular link. On the low-tension lines, and to minimize cost overheads on the customers, a I random simplex protocol is being employed. Each counter is installed with a

transmitting-only small electronic circuit in it. Each transmitter is built around a

1-chip LC, an output transistor amplifier, and a coupling circuit. The transmitters employ a DSSS modulation technique to combat the noisy and hostile power line channel and to achieve full exploitation of the available bandwidth. Rate 1/3 block repetition FEC coding together with block interleaving with an interleaving depth of 48 are employed to maximize the probability of error-free transmissions and diminish the effect of power line impulsive noise. 16-bit CRC coding is used to detect any residual errors after correction to discard the erroneous data packets. The central receiver for these transmitters is located at the distribution transformer place. A novel noise reference channel in the acquisition circuit and a novel AGC circuit were employed in the receiver design to account for the variable and unpredictable line-condition changes.