Communication Systems
in
Power Applications
Overview
Introduction
 Communication Needs of Power System
 Communication Technologies
 Existing Communication Systems
 Challenges
 Future Trends

2
Introduction
Communications is the enabling technology for
Power System
 No single communication technology as being
best suited for all power system needs
 Requirements must consider type, source,
amount, frequency, and delivery requirements of
data/voice transmitted

3
Communication Needs of Power
System

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4
Reliability
Cost effectiveness
Capacity to handle data rates
Adequate to meet response requirements
Ability to reach identified areas of power system
Ease of operation and maintenance
Security (of data and of control actions)
Communication Reliability
Reliable communication with respect to:
 Exposure to severe environment
 Electromagnetic Interference (EMI)
 Transient EMI (lightning, faults)
 Outage of transmission lines
 Power outages
 Radio paths obstructed or attenuated (by
buildings or foliage)
5
Cost Effectiveness
Communication system costs are significant
 High cost of communication system may become
an impediment
 Evaluate both first cost and lifetime operation
and maintenance costs
 Look for best trade-off between total costs and
overall performance

6
Capacity to handle data rates

Perform data rate audit of present & upcoming
schemes


Analyze each function
Determine bit rate required to perform the function
Consider worst case scenarios
 Each communications system has a bandwidth limit
 There should be at least enough bandwidth along each
path to meet data requirements
 A good margin allows for future growth and increased
system flexibility

7
Ability to meet response requirements
Response requirements (measured in sec.) are distinct
from data rate requirements (measured in kb/s or Mb/s),
and must be met independently.
Different functions have vastly different requirements for
the delivery of the information; for example:
Function
Open or close feeder switches
Acquire substation status data
Acquire feeder measurements
Acquire meter data
8
Delivery requirements
1-2 seconds
2-5 seconds
5-10 seconds
15 min. – 24 hours and up
Ability to Reach Areas of Power System
Difficult Terrain
 Communications that rely on the power line may
have difficulty

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9
During outage of line
Extreme weather conditions
Terminal equipment in outage areas may require
backup power for long durations
Ease of Operation and Maintenance
A communications system is a complex
combination of transmitters, receivers, and data
links
 Manpower not trained and not familiar with
communications equipment
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Personnel trained for new skills involved ?
New tools acquired ?
Use standardized components and
communication protocols
Security of data and control actions
Power System communication
Data & Voice have critical
importance.
Communication security is a
necessity.
11
Security of data and control actions
Your substations are an
element of the country’s
critical infrastructure – are
you sure that you are in
complete control?
12
Security of data and control actions
Maintaining the security of
communications between
the control center and field
devices is one of the most
urgent problems facing
today’s control environment.
13
Communication Technologies
Wired
Wireless
Power
Line
Carrier Microwave
Communication(PLCC)
Dedicated Leased Line VSAT
Optic Fiber
Mobile Networks
14
Power Line Carrier
Communication(PLCC)
Power Lines used for point to point communication
 Terminal equipments used to send/receive data/voice
 Works on audio band width 20 to 20 KHz
 Carrier 30 KHz to 500 KHz

15
Typical PLCC Arrangement for S/C LINE
PHASE-GROUND COUPLING
CKT-I
E/W
R
Y
B
CVT/CC
CD
E/W
R
Y
B
CVT/CC
CD
Coupling Types in PLCC System

Line Trap, Coupling Device & CC/CVT known
as Coupling Equipment
 CD consists of Surge Arrester, Drain coil,
Matching transformer, Earth switch
 Functions of Coupling Equipment
-Inject carrier signal to EHV line without loss
-Decouple carrier equipment from EHV line
17
PLCC---Uses
Voice communication
 Tele-control
 Tele-protection
 SCADA data from RTU
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PLCC---Pros
Easy availability
 Cost effective
 Ease of operation & maintenance
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PLCC--- Cons
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Limited bandwidth(4 KHz)
Data speeds up to only 1200 Bauds possible
Prone to Noise & Interference
Effect of weather conditions-frost, high pollution etc
Depends on physical connectivity of power lines
Needs government approval for carrier freq selection
Not suitable for today’s needs of automation like SAS,
remote control etc.
Fiber Optic Communication
Fiber optic cable functions as a "light guide," guiding the light introduced at one end of the cable
through to the other end. The light source can either be a light-emitting diode (LED) or a laser.
Using a lens, the light pulses are funneled into the fiber-optic medium where they travel down
the cable.

The light (near infrared) is most often are used :

850nm for shorter distances

1300nm for longer distances on Multi-mode fiber

1310-1320nm for single-mode fiber

1,500nm is used for longer distances.
Fiber Optic Communication(Contd..)
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Two types of fibreMulti mode > 50micron core– Upto 2 Kms
Single mode < 10 micron core—more than 20 Kms

Selected on the basis of distance & bandwidth needs

Wave Division Multiplexing Used
Fiber Optic (Contd..)
Pros:
Fast becoming common in utilities for voice
and data transmission
 Offer many advantages

extremely high data transmission rates
 immunity from electromagnetic interference
 Free from licensing requirements

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Cost effective for very high data transmission
rates in a point-to-point configuration
Fiber Optic (contd..)
Cons

Not as cost effective for applications, with


point-to-multipoint configuration
Modest data transmission speed requirements
Prone to cable cut in underground configuration
 Repair & restoration specialized work
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24
VSAT Communication
Geo-synchronous satellite
36,000 km
Earth Station
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User site
VSAT(contd..)
Very small aperture terminals
(VSATs) used for EMS/DMS
 For data comm. most frequently uses
a shared channel, to lower costs


SATELLITE
Communications routed through a thirdparty network management center
NETWORK
MANAGEMENT
CENTER
UTILITY
CONTROL
CENTER
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SHARED HUB
VSATs
VSAT (contd..)

Various frequency bands:


C-band (4/6 GHz), Ku-band (12/14 GHz),Kaband(30/20 GHz)
Advantages
Near-universal coverage
 Good reliability
 Fast installation

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Disadvantages
Cost
 Transmission delays
 Blackout periods due to eclipses
 Attenuation in heavy rain (Ku band)
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Mobile Communication
 Several competing technologies


Use of control channel on analog AMPS (Advanced
Mobile Phone Service), 800 MHz
CDPD (Cellular Digital Packet Data)
 The field is rapidly evolving (“2G”  “”3G”)
 Currently, most applications are for AMR
 Recently also being offered for applications in
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feeder automation
 Potentially holds the promise of economical and
wide-spread coverage
Tele-Control Protocols

IEC 60870-5-101 protocol (from RTU to Control Center
communication

IEC 60870-6-502 ( ICCP) protocol (between two Control Canters)

IEC 60870-5-103 protocol (for communication between IEDs in a
Substation)

IEC 60870-5-104 protocol

MODBUS Protocol ( MFTs)

DNP 3.0 Protocol (Serial)---Master Station

DNP 3.0 Protocol (TCP/IP)---Master Station

IEC 61850 protocol (for Substation Automation)
Tele-Control Protocols
The Present SCADA systems use

IEC 60870-5-101 for data acquisition from RTUs/SAS

IEC 60870-6-502 for data exchange between control centres
IEC–60870–5-101
Physical Layer :
Unbalanced
Request Message
Information bit : 8 bit
(User Data, Confirm Expected)
Stop bit : 1
Parity bit : Even
[P]
[S]
Master
(Acknowledgment)
Data Link Layer
Standard Frame Format : FT 1.2
Response Message
[P]
Maximum Frame Length : 255 bytes
(Request User Data)
[S]
Transmission Layer ( Station address field Length : 1 or 2 bytes )
(Respond User Data or NACK)
[P] = Primary Frame
[S] = Secondary Frame
Unbalanced Mode :
Transmitted messages are categorized on two priority classes( Class 1 & Class 2 )
Balanced Mode :
All the messages are sent, No categorization of Class 1 and Class 2
Network Layer : Not defined as 870-5-101 is not IP based
Application Layer
The length of the header fields of the data structure are:
Station address 1 or 2 byte ( User defined )
ASDU Address : 1 or 2 bytes
Information Object address : 2 bytes
Cause of Transmission : 1 byte
Slave
Selection of ASDUs
ASDU 1 : Single point information
ASDU 2 : Single point information with time tag
ASDU 3 : Double point information
ASDU 4 : Double point information with time tag
ASDU 9 : Measured value, Normalised value
ASDU 10 : Measured value, Normalised value with time tag
ASDU 11 : Measured Value, Scaled value
ASDU 12 : Measured value, Scaled value with time tag
ASDU 100 : Interrogation Command
ASDU 103 : Clock Synchronisation Command
ASDU 120 - 126 : File transfer Command
ICCP Protocol
Associations
An application Association needs to be established between two ICCP instances before any data exchange can take place.
Associations can be Initiated, Concluded or Aborted by the ICCP instances.
Bilateral Agreement and Table, Access Control
A Bilateral Agreement between two control-centers (say A and B) for data access. A Bilateral Table is a digital
representation of the Agreement.
Data Values
Data Values are objects that represent the values of control-center objects including points (Analog, Digital and Controls)
or data structures.
Data Sets
Data Sets are ordered-lists of Data Value objects that can be created locally by an ICCP server or on request by an ICCP
client
Information Messages
Information Message objects are used to exchange text or other data between Control Centers.
Transfer Sets
Transfer Set objects are used for complex data exchange schemes to transfer Data Sets (all elements or a subset of the
Data set elements) etc.
Devices
Devices are the ICCP objects that represent controllable objects in the control center.
ICCP Protocol(Contd..)
Conformance Blocks
ICCP divides the entire ICCP functionality into 9 conformance block subsets. Implementations can declare the blocks that
they provide support for, thus clearly specifying the level of ICCP supported by the implementation. Any ICCP implementation
must necessarily support Block 1ca
Block 1 – Basic Services
Association, Data Value, Data Set, Data set transfer
Block 2 – Extended Data Set Condition Monitoring
Data Set Transfer Set Condition Monitoring
Object Change condition monitoring, Integrity Timeout condition monitoring
Block 3 – Blocked Transfers
Transfer Reports with Block data
Block 4 – Information Message
Information Message objects,
IMTransfer Set objects
Block 6 to Block 9 are not generally implemented
Start Transfer
Stop Transfer
Data Set Transfer Set Condition Monitoring
Block 5 – Device Control
Device objects
Select, Operate, Get Tag, Set Tag, Timeout, Local Reset, Success, Failure
Communication Channel for Information flow
RLDC
Wide Band
Commn
(MW / FO)
SLDC
SLDC
Wide Band
Commn
Sub-LDC
Sub-LDC
Wide Band /
PLCC Commn
RTU
RTU
RTU
SCADA/EMS SYSTEM OVERVIEW
CONCEPTUAL DIAGRAM OF SCADA SYSTEM
REGIONAL LOAD AREA LOAD DISPATCH CENTRE (RLDC)
ICCP LINKS
X21 INTERFACE
STATE LOAD AREA LOAD DISPATCH CENTRE (SLDC)
AREA LOAD DISPATCH CENTRE (ALDC)
Supervisory level
Processor Interface level ( ALDC )
CCOMMUNICATION FRONT END PROCESSOR
IEC870 –5 –101
MODEM
MODEM
Communication level
MODEM
RTU
MODEM
Data acquisition and
RTU
command actuation level
T T
CT
PT
CT
Field Interface level
CR PANELS
S/STN /POWER PLANTS
POWER GRID CORPORATION OF
INDIA LTD
T T
CT
PT
CT
CONCEPTUAL SCADA
SYSTEM DIAGRAM
SCADA : Data communication architecture
TFE
computer
TFE
computer
Panel
Multi-port
Stallion
Adapters
Modem
Panel
multi-Port
Stallion
adapters
Splitter
Modem
Modem
Modem
Modem
RTU
Modem
RTU
Modem
Modem
RTU
INTER-SITE communications
Protocol management

ICCP within Open Access
Gateway
 Data acquisition and transfer to
other center(s)
 Indirect remote control (from / to
other control centers)

SCADA/
ICCP Server
ICCP
Other Sites/ICCP Server
RTU Connectivity
Normal RTU
LAN-B
Critical RTU
LAN-B
LAN-A
LAN-A
CFE
CFE
CFE
CFE
M
M
M
M
S
M
M
RTU
RTU
Interface for RTUs reporting to Control Centre
Through PLCC LINK .
Control Centre
RTU Location
Data (FSK)
Modem
RTU
Data (FSK)
PLCC
Analog
Modem
PLCC
Analog
Modem
Modem
Modem
speech
speech
Interface for RTU reporting to Control Centre via
Tandem
PLCC/Wideband Link & Wideband Links
RTU Location
Data(Fsk)
Modem
Data(Fsk)
PLCC
Speech
Control Centre
1
Primary
2
Mux
Radio
Primary
1
Mux
2
Radio
3
Modem
Sub
Mux
Analog
Speech
3
Require
--
Modem
-
--
Modem
Modem
PLCC
Analog
RTU
Speech
Wideband Node
29
Radio
28
30
Link
29
64 kbps
Sub
Mux
30
4 x E-1
4 x E-1
RTU at Wideband Node
RTU Through MICROWAVE
CFE
MUX
RADIO
TX / RX
RADIO
TX / RX
MUX
RTU
RTU Through FIBER OPTIC SYSTEM
CFE
MUX
CONTROL CENTRE
OLTE
OLTE
MUX
RTU
SUBSTATION/ GEN STN SIDE
Popular communication technologies in
Indian Power systems:
Technology

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Power Line Carrier
Analog/digital Micro wave
Fiber Optic
GSM/GPRS
V-sat
%Usage
50
15
30
<1
5
WIDEBAND COMMUNICATION SYSTEM FOR EASTERN REGION
Sub LDC
Budhipadar
ORISSA
Bodhgaya
JHARKHAND
Manpur
Hatia
Atari
Bamra
Sub LDC
Jayanagar
Mujaffarpur
Fatuha
SLDC
Patna
Biharshariff
(BSEB)
Bargaon
Tower # 313
( Repeater Shelter )
Biharshariff
(CS)
U/G
Therubali
Lalganj
Hajipur
Rajgir
Jeypore(CS)
SLDC
Ranchi
BIHAR
Kahalgaon (CS )
Kutra
Akusingha
(Repeater )
Chandil
80M
SLDC
Tarkera
Narendrapur
Maithon-G
Bokaro-B
Rourkela
(CS )
Tower # 226
( Repeater Shelter )
Jamshedpur ( CS )
Barkote
(Repater Shelter)
Mendhasal
HVDC
Mejia
Waria
WEST BENGAL
Kalipahari
Farakka(CS)
CPCC
Durgapur
Chandaka
Kalyaneswari
STPS
Tower #146
( Repeater shelter)
TSTPP
Sub LDC
Meramandali
Backup
64 KBPS
CTPS
Under PDT
Malda(CS)
Mankar
Chainpal
Backup
PDT
Burdwan
30M
SLDC
Bhubaneswar
Kamakhyanagar
Belmuri
Naupada
60M
Barchana
Backup
64 KBPS
SLDC
Backup
PDT
Howrah
Jajpur
Town
LEGEND:Microwave Link with Station
Microwave Repeater Station
Fibre Optic Link with Station
Monitoring Centre
Sub LDC
NBU
100M
Mathkargola
Vidyut
Bhavan
Jeerat
Duburi
Siliguri (CS)
Backup
64 KBPS
Kasba
DVC HQ
:
:
:
:
India Bhutan
border at
90 km
: Under Ground Fibre
ERSCC
Calcutta
100M
: RTCC link between Jey- Dgp For Indrvati
& Jeypore RTU & Backup link
WIDEBAND COMMUNICATION NETWORK FOR
NORTHERN REGION SCADA SYSTEM
PUNJAB
JAMMU & KASHMIR
RISHIKESH
HAMIRPUR
GLADNI
HARDWAR
DULHASTI
GAGAL
HIMACHAL
PRADESH
SALAL
BAIRASUIL
CHAMERA-1
ROORKEE
UTTAR PRADESH
GANGUWAL
JANIPURA
ROORKEE
KUNIHAR
CHAMERA-2
ROPAR
MUHAMDPUR
JUTOGH-SLDC
KISHENPUR
JALLANDHAR-II
URI
UDHAMPUR
WAGOORA
M E E R UT -800
MUZAFERNAGAR
MEERUT
KISHANPUR
JAMALPUR
MEERUT-220
(MODIPURAM)
HARYANA
KURALI
GORAYA
(PG) 800
NARWANA
PANCHKULA
BARNALA
MURAD NAGAR-II
TIBER
AMRITSAR
CHANDIGARH
(BBMB)
MALLERKOTLA
JALLENDHAR
M OGA
ASSANDH
GULAUTI
PANIPAT-TPS
LUDHIANA
FATEHABAD
PANIPAT-SLDC
KHURJA
M U R A D NA GA
JAGRAON
MOGA
LALTON KALAN
MALERKOTLA
GOBINDGARH
NAUSERA
DHULKOTE
HARDUAGANJ
PATIALA- SLDC
NARORA
N A L A G ARH
KAITHAL
SIKANDRA RAO
PATIALA
HISSAR
JHAJJAR
ABDULLAPUR
SONIPAT
N A T H P A JHA KRI
RATANGARH
BAHADURGARH
ETAH 123
H I S SAR
BHIWANI
DADRI SLDC
CP CC- 2
NARELA
GOPALPUR
M O R A D ABA D
WAZIRABAD
MAINPURI
PATPARGA
LACHMANGARH
BAWANA
NA R OR A
GAZIPUR
RAJASTHAN
NIBKARORI
URI
BALIA
D A U L IGA N
GORAKHPUR
SIKAR
BAHADURGARH
KHANJAWALA
RAIBAREILLY
DELHI
L U CK NO
GURSAHAIGANJ
G O R A K HPU
TANAKPUR
IP.POWER
MINTO ROAD
VINDHYACHAL
SITARGANJ
CB GA NJ
V I N D HYC HA L
U NNA O
BILHAU
LOCAL_PG
LODHI ROAD
PALSANA
U NCHHA R
R S CC
N R LDC
A L L AH ABA D
IP.EXT.
ALLAHAB
P A NK I
SINGRAULI
A U R I YA
K A NPUR
DADRI HVDC
NAJABGARH
DADRI GAS
CP CC- 1
RIHAND HVDC
SINGRAULI
DA DR I THM
KANPUR
AJGAIN
R I H A ND THM
SARITA VIHAR
REENGUS
L U K HNOW
( S A R O JNI N a gar )
DADRI
BADARPUR
AGRA
RIHAND HVDC
BADARPUR
ANTA
S H A K TI
B HA W A N
B H I W ADI
B A S SI
HINGONIA
MEHRAULI
BAMNAULI
A GR A
OKHLA
LUCKNOW
SAMESHI
RAIBAREILLY
BHIWADI
TEHRI
F A R ID ABA D
RIHAND PIPRI
MANDOLA
BALLABGARH
BAREILLY
RAE BARELI
MAINPURI
SIRSHI
B A L LA BGA RH
ALWAR
BASSI
M A N D O LA
DALLA
GAURIGANJ
H E E R APU RA
OBRA B
LEGEND
SULTANPUR
RAMGANJ
STATION
PHAGI
ROBERTGANJ
REPEATER
DEBARI
SUB SLDC
KOTA
( PG )
R A PP - A
CHITTORGARH
MALPURA
MAU AIMMA
SLDC
MARIHANE
R A PP - B
ANTA
CPCC
ALLAHABAD
KAKRAULI
NO PATH
BHINMAL
RAPP -C
FIBER
MICROWAVE
KEKRI
HANDIA
TELECOM LINK
SAHAPURA
BHILWARA
MANPURA
BIJOLIA
DABI
TALERA
KOTA
DIFFERENT PATH
AZAMGARH
VARANSI
SAHUPURI
CHUNAR
MIRZAPUR
VSAT / MEKSET LINK
POWER SYSTEM OPERATION CORPORATION LIMITED
NORTHERN REGIONAL LOAD DESPATCH CENTRE
WIDEBAND COMMUNICATION NETWORK
FOR NORTHERN REGION SCADA SYSTEM
Prepared by :
Updated on
SCADA Deptt.
:
October, 2010
Challenges
Indian Power networks growing faster, larger & more
complex.
 Data communication needs to be much faster catering
to smart grid initiatives being taken up.
 With faster, smarter & innovative technologies, data
security to be addressed adequately.
 All radio communication to be replaced with fibre optic
network by Dec.,2011 as per GOI decision.

45
Future Trends





46
Smart grid technologies driving communication needs.
High speed fibre optic networks need of the hour.
Increasing use of internet as the mechanism for data
communication.
Main thrust on security issues with use of web based
technologies.
Introduction of Service oriented architecture(SOA) will
need high band width networks.
Future Trends (contd..)
Growing insistence on adherence to
communication standards.
 Possible application of cellular digital packet
data radio technologies.

47
Thank You
Devendra Kumar
DGM,ERLDC