DESIGN AND TUNING OF DIGITAL
POWER LINE CARRIER TO IMPROVE
NETWORK LINE PARAMETERS AT HIGH
VOLTAGE TRANSMISSION LINES
Mukhtiar Hussain Khowaja
Mater’s Student, Communication System Engineering,
Institute of Information and Communication Technologies, Mehran UET, Jamshoro,
Pakistan.
E-mail: mukhtiar.ntdc@gmail.com
Irfan Ahmed Halepoto
Associate Professor, Department of Electronic Engineering, Mehran UET, Jamshoro,
Pakistan.
E-mail: irfan.halepota@faculty.muet.edu.pk
Shakeela Memon
Assistant Professor, Department of Electronic Engineering, Mehran UET, Jamshoro,
Pakistan.
E-mail: shakila.memon@faculty.muet.edu.pk
Recepción: 30/07/2019 Aceptación: 20/09/2019 Publicación: 06/11/2019
Citación sugerida:
Khowaja, M.H., Halepoto, I.A. y Memon, S. (2019). Design and tuning of digital power
line carrier to improve network line parameters at high voltage transmission lines. 3C
Tecnología. Glosas de innovación aplicadas a la pyme. Edición Especial, Noviembre 2019, 167-183.
doi: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
Suggested citation:
Khowaja, M.H., Halepoto, I.A. & Memon, S. (2019). Design and tuning of digital power
line carrier to improve network line parameters at high voltage transmission lines. 3C
Tecnología. Glosas de innovación aplicadas a la pyme. Speciaal Issue, November 2019, 167-183.
doi: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
168
169
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
ABSTRACT
In this work, Digital Power Line Carrier (DPLC) over 3-phase 500kV/220kV high
voltage transmission line is designed, congured, tuned and simulated using Micom
software. The DPLC was congured for faster and ecient data transmission at longer
distance in the range of 800km by reducing the noise using dierent 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 congured 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 conrms that line
parameters (Noise, Attenuation and BER) are improved signicantly. 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
conrms an excellent performance in terms of BER that is 99.6% error free during
the 30minutes running time.
KEYWORDS
High voltage transmission lines, Digital Power Line Carrier, 500kV Jamshoro, NKI
Karachi, Actual line Condition.
168
169
Edición Especial Special Issue Noviembre 2019
DOI: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
1. INTRODUCTION
High voltage transmission lines (HVTL) are a considered as good means of
transmitting information over dierent distance ranges. In most part of the world,
power line carrier is used to transfer information via High voltage (HV) lines and has
become an important instrument of the management and safety of electrical power
systems (Arora, Thomas & Jain, 2019). The extremely high mechanical rigidity
and high reliability of the interconnecting lines and terminal equipment under the
control of power utility exhibits attenuation and moderate to long duration noise
under normal atmospheric conditions. The HV lines exhibit attenuation in the
carrier frequency range of 20 K Hz to 500 KHz (Acakpovi, Mohammed, Nwulu,
Fifatin, Nounangnonhou, & Abubakar, 2019). Additionally the HV lines produce
high short duration level (bursts) due to the operation of circuit breakers and load
break isolators. Traditionally over HV lines, power line carrier (PLC) is widely used
because it provides multiple channels for speech, data and teleprotection (Cortes,
& Idiago, 2019). Previously analog power line carriers had been used to transfer
information/data via HV lines but due to band width limitations, noise problems
and low features in the analogue PLCs, the international recommendations for
digital power line carrier (DPLC’s) have come in to force. Additionally, the system
may have the possibility of false signals or any kind of tripping in the presence of
burst noise; the DPLC’s can combat these problems. Through DPLC, 100 to 800km
distance long range information can be transmitted without any use of repeater
stations (Ndjiongue, & Ferreira, 2019).
Digital power line carrier is consisted of processing unit, amplier unit and service
unit congured in master/slave relationship oers comprehensive transmission
capabilities over HV lines (Sagar, 2011). It supports voice/speech, data transmission
and teleprotection with various commands to react to problems in the electrical
network (Pavlidou, Vinck, Yazdani, & Honary, 2003). The DPLC has adaptive
behavior and can also be used with SCADA system. The grid information/data can
be taken from the RTU serial/parallel ports and then put to the DPLC for ecient
transmission. The additional features can be achieved by using service unit and it is
observed practically that the system does not produce perturbations or spurious noise
170
171
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
within the band. DPLC can transmit data using particular frequency band from 4
kHz to 16 kHz wide within the range of 20 to 500khz. DPLC can be congured
for wide range of parameters such as voice, data and protection of HV lines. Some
parameters are set during the manufacturing stage and some are set during the
installation and service start-up time.
2. MATERIALS AND METHODS
In this work, a DPLC based model is proposed for faster and ecient data transmission
over high voltage transmission lines by reducing the noise. The proposed model is
shown in Figure 1.
Figure 1. Proposed DPLC based model for data transmission.
In proposed model, a 3-phase HV transmission line from 500kV Jamshoro to
NKI Karachi is considered with indoor and outdoor equipment arrangement. In
this work, only single YELLOW phase is used on the existing network of National
Transmission and Dispatching Center (NTDC), Pakistan while other one or two
phases can be used for transmission of data by reducing noise. In the yard side,
outdoor equipment contains the wave trap, coupling capacitor and line matching unit
(LMU) with lightening arrestors which may protect the line equipment from heavy
lightening strokes during the rainy season. The outdoor equipment is connected with
the indoor equipment that is DPLC via HF (high frequency) cable of 75 Ω. The data
from RTU and PABX relates to DPLC for transmission.
170
171
Edición Especial Special Issue Noviembre 2019
DOI: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
2.1. DPLC CONFIGURATIONS
DPLC consists of mainly three parts; power amplier, processing module and service
module as shown in Figure 2.
Figure 2. Digital power line carrier.
2.1.1. POWER AMPLIFIER
The DPLC oers programmable amplier which is congurable with the Human-
Machine Interface that can provide 40W power and it can be increased up to 80W
for the long distance transmission HV line by adding a single AMPX unit Extension
Amplier (Waseer, Halepoto, & Joyo, 2014). The main boards that are used for power
amplier settings are amplier (AMP), transmission lter board (TXF) and reception
lter board (RXF). The AMP board is 40W class AB amplier board (Halepoto,
Kumar, Memon, & Ismaili, 2013). The TXF board is programmable 40W transmit
lter, impedance matching; summing stage for 80W is always present. Filter setting
is achieved with jumpers. Fine tuning is obtained by adjusting the inductance value
of the 2 coils (screw adjusting) on the board. RXF is board programmable receive
lter, it is only present on one of the two amplier units. Fine-tuning is obtained by
adjusting the inductance value of the three coils (screw adjusting). Jumpers on the
TXF and on the RXF allow frequency settings: the pass-band can be 4 kHz, 8kHz,
or 16 kHz wide, and is in the range 20kHz to 500kHz. After the setting of jumpers
172
173
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
the ne tuning can be performed by using selective and feeding meters. After the
completion of tuning process, the amplier is congured, as shown in Figure 3.
Figure 3 shows the power amplier conguration for 8 kHz frequency band. During
the conguration process it is very important to select the QAM center frequency for
Tx and Rx. The analog band of 4 kHz is selected for speech while other 4 kHz is
selected for DATA transmission.
Figure 3. Amplier Conguration.
2.1.2. PROCESSING UNIT
The processing unit (PRCS) is responsible to prepare the signals to be sent for the
modulation, error detection and correction scheme. The PRCS digitally samples and
modulates the signal using either QAM for normal data (to increase the data rates)
or FSK for out-of-band data. The PRCS unit oers the high speed channel V11 can
be congured by using a clock signal generated by processing unit on the master/
slave basis. The channel speed can also be set from the tool box of Micom software.
The default value is 64kbps. The Signal to Noise Ratio (SNR) or Bit Error Ratio
(BER), or both can be used as an exit and entry condition points at which the system
172
173
Edición Especial Special Issue Noviembre 2019
DOI: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
switches into or out of fallback mode. The PRCS has dierent data ports, various
combinations of DATA equipment (DTE or DCE) can be connected to DPLC. The
data channel is congured as shown in Figure 4.
Figure 4. Processing Unit conguration for DATA.
In Figure 4, the PRCS is congured for data channel. Dierent data channels are
available (DATA1, DATA2, DATA3 and DATA4) that can be used for transmission
of data at various channel speeds. It is necessary to select the same speed at both
stations. The data bits should be an integer from 1 to 9, whereas stop bit and parity
bit 1 is used.
2.1.3. USER SERVICE UNIT
The services can be expanded by adding dierent service modules (maximum up
to nine modules). The User Service Unit (USR) supports combinations of speech/
telegraph channels and data channels with up to six channels in total. Speech channels
can be congured for both analog and digital modes in the service module. The input
and output levels for analog speech is adjustable between -30db to +7db range. The
level setting should be identical at both end stations. This is set in accordance with
174
175
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
the capabilities of the PABX line to which the channel is connected.2W/4W/ denes
how many wires are to be used for the channel on the PABX. The options are two
(the default), four, or automatic detection from the PABX using W-Wire. To reduce
the noise for improving the quality of speech several combinations of equipment
such as PABX, phone and fax can be connected to the DPLC. The conguration for
speech is set as shown in Figure 5.
Figure 5. User Service Unit conguration for speech.
In Figure 5, the speech channel is congured by setting the input and output dB
levels by keeping the measured noise levels of the HV line. The burst noise and
atmospheric noise both are the main factors which aect the quality of speech. In
this work the capacitive coupling and band rejection lters are used to reduce the
noise level for the improvement of speech.
174
175
Edición Especial Special Issue Noviembre 2019
DOI: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
3. RESULTS
3.1. TRANSMISSION LINE AND NETWORK CHARACTERISTIC
PARAMETERS
In HV lines, 3-phase transmission is preferred due to minimum system losses by
using dierent methods for the transmission of speech and data. In this work, the
various characteristics of HV line are taken into consideration.
3.1.1. NOISE IN HV LINE
Noise is the random uctuations in an electrical signal, which generates an error or
undesired random disturbance in information signal. Noise is the major problem
in HVTL due to which the interruptions occur in the data dissemination from one
station to the next station. The HV lines can be aected by various types of noise
including burst noise, atmospheric (Static) noise, solar noise and etc. According to the
typical noise levels of 3-phase HVTL are given in Table 1.
Table 1. Noise levels of 3-phase HVTL.
Power line
voltage
(kV)
frequency
KHz
48-100 150 200 250 300 350 400 450
34.5-161
Fair
weather
-38 to -43 -39 to -44 -40 to-45 -41 to -46 -42 to -47 -43 to -48 -44 to -49 -45 to -50
Adverse
weather
-21to -26 -22 to -27 -23 to -28 -24 to -29 -25 to -30 -26 to -31 -27 to -32 -28 to -33
230-345
Fair
weather
-33 to -38 -34 to -39 -35 to -40 -36 to -41 -37 to -42 -38 to -43 -39 to -44 -40 to -45
Adverse
weather
-16 to -21 -17 to -22 -18 to -23 -19 to -24 -20 to -25 -21to -25 -22 to -26 -23 to -26
500
Fair
weather
-31to -36 -32 to -37 -33 to -38 -34 to -39 -35 to -40 -36 to -41 -37 to -42 -38 to -43
Adverse
weather
-11to -16 -12 to -17 -13 to -18 -14 to -19 -15 to -20 -16 to -21 -17 to -22 -18 to -23
3.1.2. LINE NOISE OF 500KV HV LINE
In this work, two stations have been selected for the measurement of noise levels
by using selective meter ALT-2000 500kv Jamshoro and 500kv NKI, Karachi. The
Table 2 shows the calculated values of noise.
176
177
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
Table 2. Line Noise of 500kv HV line.
S/No.
Frequency (KHz)
Impedance: 75 Ω
Level: 0 dBm
LMU: 48-136KHZ
Line Noise at 500kV
Jamshoro
Line Noise at NKI Karachi
ALT 2000 Settings, RF
Response at 75 Ω
ALT 2000 Settings,
RF Response at 75 Ω
1 50 -10.6 -12.6
2 60 -10.5 -12.7
3 70 -11.2 -11.4
4 80 -12.0 -13.2
5 90 -12.1 -13.7
6 100 -13.2 -14.8
7 110 -13.9 -14.9
8 120 -13.8 -15.1
9 130 -13.1 -15.2
10 140 -13.7 -15.5
3.2.1. LINE ATTENUATION
Attenuation is the loss in the transmitted signal due to line impedance and power
cable impedance. In HV lines, attenuation weakens the signal strength. The maximum
allowable attenuation is dependent on the DPLC receivers used at transmission line
terminals. Mathematically it can be calculated as follows:
Where,
Z1 is Power Cable impedance (75Ω), Z2 is line impedance (300Ω).
3.2.2. LINE ATTENUATION OF 500KV HV LINE
The line attenuation between 500kV Jamshoro and 500kV NKI, Karachi is carried
out by using ALT-2000 meter. The Table 3 showing the results of line attenuation.
Table 3. Line Attenuation of 500kV HV line.
S/No.
Frequency (KHz)
Impedance: 75 Ω
Level: 0 dBm
LMU: 48-136kHz
Line Attenuation 500kV
Jamshoro
Line Attenuation NKI Karachi
ALT 2000 Settings
RF Response at 75 Ω
ALT 2000 Settings
RF Response at 75 Ω
1 50 15.5 16.0
176
177
Edición Especial Special Issue Noviembre 2019
DOI: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
S/No.
Frequency (KHz)
Impedance: 75 Ω
Level: 0 dBm
LMU: 48-136kHz
Line Attenuation 500kV
Jamshoro
Line Attenuation NKI Karachi
ALT 2000 Settings
RF Response at 75 Ω
ALT 2000 Settings
RF Response at 75 Ω
2 60 17.3 18.2
3 70 19.6 19.0
4 80 21.4 22.4
5 90 22.8 22.0
6 100 23.5 23.0
7 110 23.9 24.0
8 120 24.1 23.0
9 130 25.3 25.0
10 140 26.2 25.5
3.3. MEASUREMENT OF INITIAL LINE CONDITION
After synchronising the both DPLCs of 500kV Jamshoro and NKI respectively,
dierent characteristics of the network were being viewed and studied for the
transmission of data over the line, but it was found that the initial condition of HV
line is very noisy as shown in the Figure 6.
Figure 6. Initial condition of HV line.
178
179
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
The Figure 6 illustrates the initial line condition with high level of noise; 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. When DPLC related to the active line at
500kV Jamshoro in direction to NKI Karachi, the Active HV line results are shown
in Figure 7.
Figure 7. Active HV line results.
Figure 7 shows the initial condition of HV transmission line which indicates the
high noise of -3.951dB and analog line gain is 10.45 dB. There are certain eects
of atmospheric conditions on the HV line, as in Figure 7 the temperature is
approximately 56.5Ċ due to which the noise increases in the line. In order to get the
desired results DPLC will be congured by setting its parameters.
4. DISCUSSION AND/OR CONCLUSIONS
During the experimental work and measurements, it was concluded that there are
certain noise problems in the HV line between from Jamshoro to Karachi. Thus,
DPLC was designed and congured to take the initial condition line spectrum.
178
179
Edición Especial Special Issue Noviembre 2019
DOI: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
4.1. TUNING AND CONFIGURATION OF DPLC FOR INITIAL LINE
CONDITION
To reduce the initial line condition noise, DPLC was tuned as shown in Figure 8.
Figure 8. Low noise in Rx band after DPLC tuning.
Figure 9. Reduced Noise Measurement Window.
180
181
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
From Figure 8, it can be observed that in Rx band from 116kHZ to 124kHZ the
spectrum is much better as compared to Figure 6. The noise measurement window
is shown in Figure 9, where the noise level is decreased from -3.951dB to -13.4dB
due to which the AGC is also improved. On this line, the data transmission can be
observed in terms of BER as shown in Figure 10.
Figure 10. Improved BER.
When DPLC was used for data transmission as shown Figure 10, it conrms an
excellent performance in terms of BER that is 99.6% error free during the 30min
running time.
5. ACKNOWLEDGMENTS
Authors are highly grateful to Mehran University of Engineering and Technology,
Jamshoro, Pakistan, for the necessary support, technical laboratory facilities and
comfortable research environment.
180
181
Edición Especial Special Issue Noviembre 2019
DOI: http://dx.doi.org/10.17993/3ctecno.2019.specialissue3.167-183
REFERENCES
Acakpovi, A., Mohammed, H., Nwulu, N., Fifatin, F. X. N., Nounangnonhou,
T. C., & Abubakar, R. (2019). Evaluation of Noise Eects on Power Line
Communication in a Narrow and Wide Band Frequency Spectrum: A Case Study
of Electricity Distribution Network of Ghana. In IEEE International Conference on
Computing, Computational Modelling and Applications (ICCMA), 27-276. doi: https://
doi.org/10.1109/ICCMA.2019.00012
Arora, S., Thomas, M. S., & Jain, M. (2019). Designing Coupling Circuits for
Communication of High-Frequency Signals over Power Lines. In Advances in
System Optimization and Control, 47-63. Springer, Singapore. doi: https://doi.
org/10.1007/978-981-13-0665-5_5
Cortés, J. A., & Idiago, J. M. (2019). Smart Metering Systems Based on Power
Line Communications. In Smart Grids and Their Communication Systems, 121-170.
Springer, Singapore. doi: https://doi.org/10.1007/978-981-13-1768-2_4
Halepoto, I. A., Kumar, W., Memon, T. D., & Ismaili, I. A. (2013). Quantifying
the Eect of Lookup Table Size and Coecients Complexity for Non-Linearity
Compensation in Power Ampliers. Sindh University Research Journal (Science
Series), 45(2), 447-452. Retrieved from: https://www.academia.edu/9011941/
Quantifying_the_effect_of_Look_up_Table_Size_and_Coefficients_
Complexity_for_Non-Linearity_Compensation_in_Power_Ampliers
Ndjiongue, A. R., & Ferreira, H. C. (2019). Power line communications (PLC)
technology: More than 20 years of intense research. Transactions on Emerging
Telecommunications Technologies, 30(7), e3575. doi: https://doi.org/10.1002/ett.3575
Pavlidou, N., Vinck, A. H., Yazdani, J., & Honary, B. (2003). Power line
communications: state of the art and future trends. IEEE Communications
magazine, 41(4), 34-40. doi: https://doi.org/10.1109/MCOM.2003.1193972
Sagar, N. (2011). Powerline Communications Systems: Overview and Analysis (Doctoral
dissertation, Rutgers University-Graduate School-New Brunswick).
182
183
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254–4143
Waseer, T. A., Halepoto, I. A., & Joyo, M. A. (2014). Quantifying the Q-factor and
minimizing BER in 32-channel DWDM system design using EDFA and RAMAN
ampliers. Mehran University Research Journal of Engineering and Technology, 33(1), 1-8.
Retrieved from: https://www.ingentaconnect.com/content/doaj/02547821/20
14/00000033/00000001/art00001
