Design and tuning of digital power line carrier to improve network line parameters at high voltage transmission lines

In this work, Digital Power Line Carrier (DPLC) over 3-phase 500kV/220kV high voltage transmission line is designed, configured, tuned and simulated using Micom software. The DPLC was configured for faster and efficient data transmission at longer distance in the range of 800km by reducing the noise using different enhanced digital techniques and advanced indoor/outdoor equipment. In this work, only YELLOW phase of 3-phase is used on the existing network of National Transmission and Dispatching Center, Pakistan while other phases can be used for transmission of data by reducing noise. The line matching units, coupling capacitors, wave traps and high frequency cables for the connection of DPLC to the HV line in grid yard were considered. The Actual line condition measurent for attenuation and noise were carried out between two remote stations between 500kV Jamshoro and NKI Karachi. The line spectrum shows that in Rx (116 KHz to 124 KHz) band there is very high level of noise during the sweep time of 10sec, the initial condition of HV transmission line indicates the high noise of -3.951dB and analog line gain of 10.45 dB. To reduce this noise level, the DPLC was configured according to the line parameters. After synchronizing the both DPLCs of 500kV Jamshoro and NKI Karachi, the initial line condition of HV line were measured again. The result confirms that line parameters (Noise, Attenuation and BER) are improved significantly. The results shows the in Rx band from 116kHZ to 124kHZ line spectrum, the noise level is decreased from -3.951dB to -13.471dB due to which the analog line gain was also improved from 10.45dB to 19dB. When DPLC was used for data transmission it confirms an excellent performance in terms of BER that is 99.6% error free during the 30minutes running time.