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A New Low Cost Coupling System for Power
Line Communication on Medium Voltage Smart
grids
Giovanni Artale, Student Member IEEE, Antonio Cataliotti, Member IEEE, Valentina Cosentino,
Dario Di Cara, Member IEEE, Riccardo Fiorelli, Salvatore Guaiana, Giovanni Tinè, Member IEEE

Abstract—The paper proposes and verifies the performance of an
innovative and low cost coupling system for power line
communication (PLC) on medium voltage (MV) smart grids. The
coupling system makes use of the capacitive divider of the voltage
detecting systems (VDS) to inject and receive the PLC signal.
VDS are usually already installed in the MV switchboards of the
major electrical manufacturer all over the world according to
IEC 61243-5. VDS are used to detect the presence of the mains
voltage to guarantee personnel safety. An interface circuit has
been developed to be connected between the PLC transceiver and
the VDS socket. In this way, the PLC signal can be coupled to the
MV network without installing a dedicated MV coupler, thus
avoiding the related costs of the coupler, the installation, and the
temporary service interruption. The innovative device is able to
couple digitally modulated narrowband PLC signals with
modulation rate up to 19.2 kbit/s. In the paper, firstly a
description of the proposed solution is reported. Secondly, its
communication performance has been tested in laboratory.
Finally, different tests have been carried out in two MV smart
grid real installations under normal operation, i.e in the presence
of the mains voltage.
Index Terms—Power system communication, communication
systems, couplers, narrow band power line communication,
communication signal couplers, power system communication,
power system measurements, smart grids.
I. INTRODUCTION
T
HE transmission of communication signals through the
medium voltage lines (MV) is gaining an increasing
interest in recent years. The development of the
distribution networks into smart grids requires a continuous
exchange of data between the distribution system operator
(DSO) and the energy users and prosumers related to different
This research was supported by StMicroelectronics. The authors wish to
thank Eng. Salvatore Russotto (Impresa Elettrica D’Anna e Bonaccorsi s.n.c.)
and Eng. Marco La Russa (SEA Spa) for their support during the Ustica and
Favignana field tests respectively.
Giovanni Artale, Antonio Cataliotti, Valentina Cosentino, and Salvatore
Guaiana, are with the Department of Energy, Information engineering and
Mathematic Models (DEIM), Università degli Studi di Palermo, Italy (email:
giovanni.artale@unipa.it, acataliotti@ieee.org, cosentino@dieet.unipa.it,
salvatore.guaiana@unipa.it)
Dario Di Cara, and Giovanni Tinè are with the Institute of Intelligent
System for Automation (ISSIA), National Research Council (CNR), Palermo,
Italy, (e-mail: dicara@pa.issia.cnr.it, tine@pa.issia.cnr.it).
R. Fiorelli is with the ST Microelectronics S.r.l., Agrate 20864, Italy (email: riccardo.fiorelli@st.com).
smart applications, such as the remote control of secondary
substation equipment, the automatic meter reading (AMR), the
monitoring of distribution network power flows, and so on
[1]-[7]. For these purposes, wireless or GSM systems are
usually suggested, even if they have weak reliability
(particularly in bad weather conditions) and a high intrinsic
cost of the communication provider. Besides these
communication systems, narrowband PLC has been chosen
and already widely implemented to support different smart
applications, such as automatic meter reading and demand side
management applications in low voltage (LV) networks [8].
The use of PLC is also suggested by recent standards on the
connection of distributed generation and its remote control.
Despite a slower transmission data rate, narrowband PLC has
the great advantage of a lower installation cost, because the
power lines are already present, and they have no service cost
for the communication provider, because the DSO is usually
owner of the power lines. Moreover, PLC is also more secure
from cyber-attacks because the communication system is not
easily accessible from an intruder. Other advantages of PLC,
when it is employed for utility applications, are summarized
below [9]: redundancy in protection and control is an utility
typical requirements and it can be obtained only with a
redundant communication system, which can be easily and
economically supported by PLC based on an existing wired
infrastructure; PLC uses the most direct route between
controllers and distributed IEDs, thus can allows to obtain
lower latencies when compared to packet switched public
networks; the PLC channel, i.e. the power line, is under the
direct and complete control of the utility which is a
fundamental benefit in those countries where the
communication market is deregulated. For these reasons, the
PLC solution can be used as redundant communication system
in parallel to a faster communication system or it can be used
for those applications which have lower transmission data rate
requirements, when important messages has to be delivered
such as commands or signals on the status of the network, or
when data has to be collected off-line, such as in meter
reading systems. On the other hand, few commercial solutions
are available for power line communication (PLC) on MV
networks. Some new studies have been developed in recent
years to understand the behavior both of the line and of the
power transformer in the PLC frequency range [10]-[11]. The
authors have also deeply investigated this topic [12]-[14],
developing a model of the different components of the
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electrical network in the frequency range 50 - 148 kHz, which
is reserved for the PLC signal transmission by the CENELEC
EN 50065-1 [15]. On the other hand, the main problem in the
application of the PLC in the MV networks is the design of the
MV signal coupler. It must have, as well as high electrical
insulation, high impedance at the mains frequency, to isolate
the signal circuit from the MV network, and at the same time
it should have low impedance at the PLC frequency band and
suitable bandwidth to transmit PLC signals with different
digital modulations. Hence, most of the commercial and
research solutions are based on the use of a dedicated MV
coupler, capacitive or inductive, to be installed both in the
primary substation and in each secondary substation.
Therefore, these solutions have a high installation cost due to
the large amount of expensive MV couplers to be installed to
cover the whole network. Moreover, the installation is not
easy inside the existing air insulated MV switchboard and
even more for the gas insulated ones. Furthermore, the
installation requires a temporary disconnection of the
substation, thus causing further costs and drawbacks for the
temporary service interruption [17]. The possibility to use
alternative solutions based on voltage dividers usually
installed in MV substations, i.e. voltage transformer or
capacitive coupler of voltage detecting systems (VDS), was
analyzed in [18] by concluding that these voltage dividers are
not adequate as coupler for PLC application. In this paper, the
authors propose an innovative PLC coupler based on the use
of the capacitive divider of the VDS, which is able to transmit
narrowband PLC signals with a bandwidth corresponding to a
symbol rate up to 9600 baud/s and modulation rate up to 19.2
kbit/s. VDS are normally installed worldwide in medium
voltage (from 1 kV to 52 kV) switchgears, used both in
primary and secondary substations, for detecting the presence
or the absence of the operating voltage in order to ensure the
safety of the operators. More in detail, a capacitive divider
inside MV switchgears provides a low-voltage signal that
feeds a voltage presence detector. Usually, separable
indicators are used. They have an audible or visible output,
such as a blinking light, and they have a two-phase plug to be
connected on a proper socket embedded in the MV
switchboard. In Fig. 1, a MV switchboard is shown,
highlighting the VDS socket panel and the separable indicator.
A schematic diagram of a unipolar voltage detection system is
shown in Fig. 2, according to the international reference
standard IEC 61243-5 [19]. The proposed coupling solution
patented by the authors in [20] suggests injecting the PLC
signal through the VDS socket by allowing a bidirectional
communication through the MV power line and without
modifying the MV switchboard. In this way, no dedicated MV
PLC coupler has to be installed. Thus a high reduction of the
costs is obtained, because:
 the MV coupler cost is higher than the electronic
interface board one;
 no modification of the MV switchboard is required;
 no service interruption is needed for its installation;
 the installation itself is easier and faster, thus a
reduction in the cost of manpower is also obtained.
2
Fig. 1. Voltage detecting system in a MV switchboard of a secondary
substation.
In this paper, the new solution principle of operation is
firstly described and the developed interface circuit prototype
is presented. Secondly, communication performance has been
tested on a laboratory test bench. Finally, the performance of
the proposed solution was tested in two MV smart grid cases
under normal operation, i.e. presence of mains voltage, AMR
PLC signals and noise with different MV network topologies.
II. THE NEW PLC COUPLING SOLUTION: BASIC PRINCIPLE
According to the standard IEC 61243-5 [19], a VDS is
composed of the different elements shown in Fig. 2. The MV
capacitive divider is given by a capacitance of fixed value
which has one terminal connected to the MV bus-bars and the
second terminal which is available for the voltage detection.
Between the second terminal and the earth, the following
devices are connected: a voltage limiting device, a measuring
circuit component, and a short circuiting device. The behavior
of these devices can be modeled as an equivalent capacitance,
also including stray capacitances. When the mains voltage is
applied to the series of the equivalent capacitance and the MV
divider capacitance, a reduced proportional voltage is
available at the VDS socket terminals. The voltage reduction
ratio is proportional to the capacitance ratio. Thus, to have a
significant reduction, the equivalent capacitance should be at
least 20 times larger than the MV divider capacitance. In this
way, a voltage indicator connected to the VDS sockets can
detect the presence or the absence of the main voltage. This
type of voltage detector is defined as separable system. The
standard [19] classifies five different separable systems,
defining the relative dimensional characteristic of the sockets
and of the plug arrangement. The idea of the patent is to
substitute the voltage indicator with a plug of the same
dimension, through which the PLC signal can be injected or
received. In this way, no modifications of the MV switchgear
are required. On the other hand, the PLC transceiver cannot be
directly connected to the VDS socket, because the signal
would be almost totally short circuited to earth by the
equivalent capacitance of stray and measuring circuit
component capacitance, which, at the PLC signal frequencies,
has lower impedance than the MV divider capacitance. To
solve this problem, an interface card is connected between the
transceiver and the VDS socket, as shown in Fig. 3 [20]. In
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this configuration, the signal is injected between the core of
one of the three cables and the shield connected to earth.
As regards the interface card, two different circuits were
designed, as shown in Fig. 3: one for transmission (Tx) and
one for reception (Rx). The PLC transceiver sends a digital
output to the two switches, to select the desired circuit (Tx or
Rx). Each circuit has a variable inductance to be connected in
parallel to the VDS socket. This inductance creates a parallel
resonant circuit with the equivalent capacitance at the PLC
signal center frequency. In this way, in Tx operating condition
a high impedance route to earth is created and only a small
part of the transmitted signal is short circuited to earth, while
the largest part of the signal is driven to the MV network.
Fig. 2. Voltage detecting system with portable indicator (separable VDS) [19].
Fig. 3. Schematic circuit of the interface card: reception (Rx) circuit and transmission (Tx) circuit
Fig. 4. Schematic circuit of the laboratory test bench.
In addition, thanks to the impedance matching circuit, as
shown in Fig. 3, an impedance matching is created between
the transmitting output impedance and the MV capacitive
divider impedance, thus obtaining the maximum signal
transfer to the MV network. In Rx operating condition, the
variable inductance is adjusted to obtain the largest impedance
between line and earth terminals, in the PLC frequency range.
As a result, the maximum signal voltage level is obtained at
the VDS socket. In addition, a pass-band filter helps to
discriminate the PLC signal from the noise. An amplifier is
embedded in both Rx and Tx circuits of the interface card in
order to increase the PLC signal level injected and received
from the MV line [20]. In this study the single phase to earth
configuration is used to transmit the PLC signal. The interface
board is connected to only one of the three sockets, thus the
signal is injected trough one of the capacitive dividers into the
correspondent core cable. More complicated solutions could
be obtained, by using two or three cables, with an increase of
cost and complexity. Though a benefit could be obtained with
these multiphase solutions in terms of received signal
amplitude or bandwidth, in this first step of the research the
single phase solution was chosen for its simplicity and its
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cheapness. Moreover, a demonstration of the reliability of this
simplest solution can open new prospective for the
development of more complicated solutions.
4
tests confirmed that the proposed PLC coupling system
requirements of symbol rate and frequency bandwidth were
respected.
III. LABORATORY EXPERIMENTAL TESTS
A laboratory test bench was set-up as shown in Fig. 4, in
order to characterize the electrical behavior of the interface
card prototype and to verify its communication performance.
The laboratory tests are performed without considering the
presence of the mains voltage. Two sets of three capacitive
dividers, similar to the ones used in the MV switchgears, are
connected at the ends of three 15-m-long MV unipolar cables,
type RG7H1R, with 50 mm2 aluminum core cross-section and
copper shield. The two triads of capacitive dividers are from
different manufacturers. They are connected to a VDS panel,
which respects the requirements of the IEC 61243-5 MR type
[19]. This type of VDS is used in most of the MV switchgears
installed by the major distributor system operators of Italy.
The PLC modem and the interface card are allocated in a
metallic box together with a transformer based power supply,
which provides different DC supplying voltage levels. The
PLC modem EVALST7580 [21] is used to generate the nPSK
signal in the frequency range 9 kHz – 250 kHz. The interface
card output is connected to the VDS panel by means of a
modified standard plug. Transmitted and received signal
spectra were measured with a digital oscilloscope Rohde &
Schwarz RTO 1044 at the PLC modem transceiver terminals.
The characterization of the interface card was focused at the
center frequency of 110 kHz, because it is far enough from the
AMR PLC carrier frequencies which are usually in the
frequency range 70-90 kHz. Moreover, the chosen center
frequency is inside a band where low noise was measured in
the on-field tests [14]. Firstly, a characterization of the
interface card was performed. A signal generator was
connected at the interface card input. A sweep signal was
generated with 110 kHz center frequency, 50 kHz span, and
1.5 VPP amplitude. The frequency spectrum of the received
signal is shown in Fig. 5. As can be seen, it has a resonant
behavior which allows efficiently receiving the narrow-band
PLC signal from the MV network. More in detail, a 6 dB band
of 15 kHz was measured around the center frequency, which is
compatible with the required band of the modulation used by
the ST7580 modem, i.e. nPSK modulated signal with 9600
baud/s. To verify the communication performance of the VDS
system, PLC modulated signals with different bit rates were
considered. The performance of the coupling system was
evaluated by measuring the success rate, i.e. the percentage of
received information packets with respect to the transmitted
packet number. Different tests were performed by considering
1000 packets for each transmission test and by varying the
modulation technique and the amplitude of the transmitted
signal. In the laboratory tests, all transmitted packets were
correctly received (success rate = 100%), whatever the
amplitude of the transmitted signal and the modulation
technique (even with QPSK modulation at 19.2 kbit/s). In Fig.
6 the measured spectrum of the received signal is shown when
a QPSK modulated signal was transmitted. The laboratory
Fig. 5. Spectrum of the received signal measured in laboratory during a
frequency sweep test.
IV. ON-FIELD EXPERIMENTAL TESTS
In this section, the VDS coupler performance is verified in
different real environments, i.e. in MV smart grids of different
topologies and line lengths. All on-field tests were performed
in the presence of the mains voltage (i.e. 20 kV, 50 Hz), AMR
PLC signals and noise. More in detail, tests were performed in
four MV network topologies described in the following:
 MV line connecting a by-pass substation and a terminal
substation, with an intermediate by-pass substation;
 MV line connecting two by-pass substations, with an
intermediate by-pass substation;
 MV line connecting a nodal and a by-pass substation;
 MV line connecting two nodal substations, with an
intermediate nodal substation.
The by-pass configuration is the operating condition when a
substation has only two MV switches, one for the arriving and
one for the departing line, and both switches are closed. On
the other hand, in the terminal configuration the departing line
switch is left open. The nodal configuration, instead, is the
operating condition when a substation has one MV switch
closed on the arriving line and two or more than two MV
switches closed on different departing lines.
A. 1 st topology: a by-pass and a terminal substation
A first test campaign was performed in the MV smart grid
of the island of Ustica, in the Mediterranean sea. The two
substations named Spalmatore and Sidoti were chosen because
they can be both configured in by-pass or terminal
configurations [12]. The MV line connecting the two
substations is 1.4 km long and it is made by unipolar cables
RG7H1R type with 25 mm2 aluminum core cross-section and
copper shield. In each of the two substations, a 20/0.4 kV/kV
power transformer is installed with rated power of 100 and
160 kVA, respectively. An intermediate by-pass MV
substation is connected near substation Spalmatore.
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were not correctly received. In particular, for BPSK uncoded a
success rate of 98.4% was obtained. The received spectrum
measured in this operation condition is shown in Fig. 10.
Fig. 6. Spectrum of the received signal measured in laboratory in the case a
QPSK modulation was selected.
The intermediate substation is named Villaggio and it
supplies a MV user. In Fig. 7, an electrical scheme is shown
for the MV line under test, which connects the three secondary
substations in by-pass configuration. The MV switchgears of
each substation are equipped with the MR-type VDS, same as
those used in laboratory. The PLC station assembled inside the
Sidoti substation is shown in Fig. 8. The picture shows the
interface card prototype with the PLC transceivers (Modem)
connected to the VDS socket panel. More in detail, the signal
is injected into a chosen phase of the three phase VDS sockets.
Similarly a second PLC station was assembled inside the
Spalmatore substation and it was connected to the VDS socket
correspondent to the chosen phase of the MV line. In this case
the Sidoti and Spalmatore substations were in terminal and in
by-pass configuration, respectively. The experimental results
obtained are reported in Table I. Each test was performed
transmitting 1500 packets and a success rate of almost 100%
was found selecting different modulation techniques with bit
rate up to 9600 bit/s. A reduction of the success rate to 98%
was found when the transmission data rate was increased to
19200 bit/s, by using the QPSK modulation technique without
error correction coding. In this last case, the spectrum of the
received signal was measured. It is shown in Fig. 9 (red line)
along with the noise (blue line) measured when the
transmission signal was switched off. As can be seen, thanks
to the interface card prototype, the received signal level is
higher than the measured noise and thus it can be correctly
demodulated by the transceiver. Tests were also performed by
using the FSK modulation technique and by varying the
related bit rate. A success rate of 97% was found with the bit
rate of 9600 bit/s, thus demonstrating a lower immunity to the
noise with respect to the nPSK modulation technique, which
has a higher success rate with the same bit rate.
B. 2nd topology: two by-pass substations
The transmission results obtained in the second topology
(both substations in by-pass configuration) are reported in
Table II. Also in this case, for each test 1500 packets were
transmitted. A success rate of 100% was obtained for BPSK
coded and QPSK coded, while with faster but uncoded
modulations the success rate decreased because many packets
Fig. 7. Ustica MV line connecting two by-pass substations, with an
intermediate by pass substation.
Fig. 8. Transmission station assembled inside the Sidoti substation. An
interface card prototype is connected to the VDS socket panel.
TABLE I.
VDS COMMUNICATION TESTS IN THE 1ST NETWORK TOPOLOGY :
S UBSTATION “SPALMATORE” IN TERMINAL CONNECTION,
SUBSTATION “SIDOTI” IN BY PASS CONNECTION
Modulation
Symbol rate Bit rate Packet Correctly Invalid
Success
Lost
[baud/s]
[bit/s] sent received Counter
rate
BPSK coded
9600
4800
1500
1500
0
0
100%
QPSK coded
9600
9600
1500
1500
0
0
100%
BPSK
9600
9600
1500
1499
1
0
99.9%
QPSK
9600
19200 1500
1472
28
0
98.1%
BFSK
2400
2400
1500
1497
1
2
99.8%
BFSK
4800
4800
1500
1485
10
5
99.0%
BFSK
9600
9600
1500
1460
15
25 97.3%
C. 3 nd topology: a nodal and a by-pass substation.
Another test campaign was performed in the MV smart grid
of the island of Favignana, in the Mediterranean sea. The
communication tests were performed between the two
substations named “Gen. Di Vita” and “4 Vanelle”. The Gen.
Di Vita substation is always in by-pass configuration. 4
Vanelle, instead, is a nodal substation with five MV
switchgears, as shown in Fig. 11 and Fig. 12. The MV
switchgears allow to connect the MV bus-bars to the power
transformer, the incoming MV line (C10) and the three
departing lines (C15, C06 and C08). The C06 departing line is
connected to the Gen. Di Vita substation. This line is 1.1 km
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long and it is made by unipolar cables RG7H1R type with 50
mm2 aluminum core cross-section and copper shield.
Fig. 9. Spalmatore substation: the received QPSK signal spectrum is shown
along with the noise measured in the first network topology.
6
success rate higher than 98% was obtained with the
modulation techniques up to 19.2 kbit/s (QPSK). In Fig. 14
and Fig. 15, the received signal spectrum is shown in the case
of QPSK modulation for the two transmission directions. A
lower received signal level was measured in Gen. Di Vita
substation, Fig. 15. These results suggest that the departing
lines of the nodal substation 4 Vanelle have a higher influence
when the substation is used to transmit the signal, draining
part of its power and causing a reduction of the signal level at
the receiving substation.
Fig. 11. Electrical scheme of 4 Vanelle substation. Five MV switchgears are
installed which connect the power transformer, the incoming MV line and
three departing lines, one of which is connected to substation C06 Gen. Di
Vita.
TABLE III.
VDS COMMUNICATION TESTS IN THE 3RD NETWORK TOPOLOGY :
TX GEN. DI VITA ( BY -PASS)  RX 4 VANELLE (NODAL)
Modulation
Fig. 10. Spalmatore substation: the received BPSK signal spectrum is shown
along with the noise measured in the second network topology.
TABLE II.
VDS COMMUNICATION TESTS IN THE 2ND NETWORK TOPOLOGY :
BOTH SUBSTATIONS IN BY PASS CONNECTION
Modulation
Success
Bit rate Packet Correctly Invalid
Lost
[bit/s] sent received Counter
rate
BPSK coded
4800
1500
1500
QPSK coded
BPSK
QPSK
0
0
9600
1500
9600
1500
19200
1500
100%
1500
0
0
100%
1476
22
2
98.4%
1461
31
8
97.4%
In each of the two substations, a 20/0.4 kV/kV power
transformer is installed with rated power of 160 and 250 kVA,
respectively. The PLC station assembled inside the 4 Vanelle
substation is shown in Fig. 13. The experimental tests were
performed in the two transmission directions, i.e. transmitting
from Gen. Di Vita and receiving in 4 Vanelle and viceversa.
Also in this case, the tests were performed by transmitting
1500 packets. In Table III and Table IV, the experimental
results are shown for the two transmission directions. A
Bit rate Packet Correctly Invalid
Success
Lost
[bit/s]
sent received Counter
rate
BPSK coded
4800
1500
1500
0
0
100%
QPSK coded
9600
1500
1499
0
1
99.9%
BPSK
9600
1500
1498
2
0
99.8%
QPSK
19200
1500
1494
5
1
99.6%
BFSK
9600
1500
1488
8
4
99.2%
D. 4 th topology: two nodal substations.
A final test campaign was performed between the two nodal
substations of Favignana MV network named “Torregrossa”
and “4 Vanelle”. Torregrossa is a nodal substation with three
MV line switchgears, and a fourth switchgear which connects
the 250 kVA power transformer. An intermediate substation,
named “S. Francesco”, is connected between the two chosen
substations, as shown in Fig. 16. S. Francesco is a nodal
substation with one arriving line from 4 Vanelle substation,
and two departing lines, one of which is connected to
Torregrossa substation. The MV line which connects S.
Francesco to 4 Vanelle is 1.6 km long and it has a 50 mm2
core cross section while the one that connects S. Francesco
substation to Torregrossa substation is 0.2 km long and it has a
25 mm2 core cross section. In Table V and Table VI, the
transmission results are reported for the two transmission
directions, i.e. from 4 Vanelle to Torregrossa and vice versa.
Also in this case, worse results are obtained when the signal is
transmitted from 4 Vanelle substation, because it has a higher
number of departing lines. It can be concluded that even
increasing the distance between the PLC stations (up to 1.8
km) and considering an intermediate nodal substation, it is still
possible to transmit a PLC signal but with lower bit rate (the
fastest achievable bitrate for a bidirectional communication is
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4800 bit/s with a BPSK-coded modulation technique). In
Table VII the on-field experimental results for bidirectional
communication are summarized reporting for each topology
the fastest achievable bitrate corresponding to a minimum
success rate of 98%.
7
absence of the operating voltage in order to ensure the safety
of the operators according to the international reference
standard IEC 61243-5 [19]. Many experimental results were
collected on field in two MV smart grids with different
topologies and line lengths and in normal operation condition.
The experimental tests demonstrate that the proposed solution
could be reliably used for many smart grid applications, in
which a capillary communication system is needed with no
high speed requirements, such as automatic meter reading,
remote control of secondary substation equipment or MV
distributed generators, monitoring of distribution network
power flows and so on.
Fig. 12. Favignana MV line connecting a nodal and a by-pass substation,
named “4 Vanelle” and “G. Di Vita”, respectively.
TABLE IV.
VDS COMMUNICATION TESTS IN THE 3RD NETWORK TOPOLOGY :
TX 4 VANELLE (NODAL)  RX GEN . DI V ITA ( BY-PASS)
Modulation
Bit rate Packet Correctly Invalid
Success
Lost
[bit/s]
sent received Counter
rate
BPSK coded
4800
1500
1500
0
0
100%
QPSK coded
9600
1500
1496
4
0
99.7%
BPSK
9600
1500
1480
19
1
98.7%
QPSK
19200
1500
1472
26
2
98.1%
BFSK
2400
1500
1498
2
0
99.9%
BFSK
9600
1500
1475
8
17
98.3%
Fig. 14. 4 Vanelle substation: the received QPSK signal spectrum is shown
along with the measured noise in the third network topology.
Fig. 13. Transmission station assembled inside 4 Vanelle substation.
V. CONCLUSION
This paper presents an innovative low cost coupling system
for MV network, able to transmit narrowband PLC signals
with a frequency band corresponding to a maximum symbol
rate of 9600 baud/s and modulation rate up to 19.2 kbit/s. The
proposed coupling solution suggests injecting the PLC signal
through the VDS socket by allowing a bidirectional
communication through the MV power line, without
modifying the MV switchboard or installing a dedicated MV
PLC coupler. VDS are normally installed worldwide in
medium voltage switchgears used both in primary and
secondary substations, for detecting the presence or the
Fig. 15. Gen. Di Vita substation: the received QPSK signal spectrum is shown
along with the measured noise in the third network topology.
These test results represent a first step of the research with
the aim of demonstrating the feasibility of the proposed
solution as PLC coupler. In future, the performance of the
proposed solution will be investigated in different frequency
ranges. As an example an investigation should be performed
to verify the coupler performances in the CENELEC A
frequency band and its coexistence with AMR signals. The
increase of the transmission bandwidth will be also
investigated in order to transmit OFDM signals with faster
data rate. Moreover, the possibility to use different MV
1949-3053 (c) 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TSG.2016.2630804, IEEE
Transactions on Smart Grid
> REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) <
electrical components as PLC coupler will be also studied,
with a particular attention to the voltage presence indicating
systems, regulated by IEC 62271-206, whose behavior at the
PLC signal could be very similar to that of the VDS. Finally, a
study will be conducted to incorporate in the new coupling
solution the original functionality at the mains frequency, i.e.
the voltage detection which is of utmost importance for the
electrical operator safety.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
Fig. 16. Favignana MV line connecting the two nodal substations, named “4
Vanelle” and “Torregrossa”. A third nodal substation, named “S. Francesco”,
is connected in the middle of the MV line.
[8]
[9]
TABLE V.
TH
VDS COMMUNICATION TESTS IN THE 4 NETWORK TOPOLOGY :
TX 4 VANELLE (NODAL) TO RX TORREGROSSA (NODAL)
Modulation
[10]
Bit rate Packet Correctly Invalid
Success
Lost
[bit/s] sent received Counter
rate
BPSK coded
4800
1500
1485
14
1
99.0%
QPSK coded
9600
1500
1292
120
88
86.1%
BPSK
9600
1500
1124
270
106
74.9%
BFSK
4800
1500
1460
20
20
97.3%
[12]
TABLE VI.
VDS COMMUNICATION TESTS IN THE 4TH NETWORK TOPOLOGY :
TX TORREGROSSA (NODAL) TO RX 4 VANELLE (NODAL)
[13]
Modulation
[11]
Bit rate Packet Correctly Invalid
Success
Lost
[bit/s] sent received Counter
rate
BPSK coded
4800
1500
1497
3
0
99.8%
QPSK coded
9600
1500
1499
1
0
99.9%
BPSK
9600
1500
1475
4
21
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QPSK
19200
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1473
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98.2%
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1472
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[14]
[15]
[16]
TABLE VII.
VDS BIDIRECTIONAL COMMUNICATION
FASTEST ACHIEVABLE BITRATE FOR EACH MV NETWORK TOPOLOGY
[17]
[18]
Topology
Operating condition
of the substations
Line
length
[km]
Bit
rate
[bit/s]
Modulation
1st
terminal – by pass – by pass
1.4
19200
QPSK
[19]
nd
by pass – by pass – by pass
1.4
9600
QPSK coded
[20]
3rd
nodal – by pass
1.1
19200
QPSK
4th
nodal – nodal - nodal
1.8
4800
BPSK coded
2
8
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