Communication Systems in Power Applications 2 Overview n Introduction n Communication Needs of Power System n Communication Technologies n Existing Communication.

Communication Systems

in

Power Applications

2

Overview Introduction Communication Needs of Power System Communication Technologies Existing Communication Systems Challenges Future Trends

3

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

4

Communication Needs of Power System

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)

5

Communication ReliabilityReliable 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)

6

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

7

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

8

Ability to meet response requirements

Function Delivery requirements

Open or close feeder switches 1-2 seconds

Acquire substation status data 2-5 seconds

Acquire feeder measurements 5-10 seconds

Acquire meter data 15 min. – 24 hours and up

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:

9

Ability to Reach Areas of Power System Difficult Terrain Communications that rely on the power line may

have difficulty During outage of line Extreme weather conditions

Terminal equipment in outage areas may require backup power for long durations

10

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 Personnel trained for new skills involved ? New tools acquired ?

Use standardized components and communication protocols

11

Security of data and control actionsPower System communication Data & Voice have critical importance.Communication security is a necessity.

12

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?

13

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.

14

Communication Technologies

Wired Wireless

Power Line Carrier Communication(PLCC)

Microwave

Dedicated Leased Line VSAT Optic Fiber Mobile Networks

15

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

Typical PLCC Arrangement for S/C LINE

PHASE-GROUND COUPLING

CD

PL

CC

PL

CC

PL

CC

PL

CC

CKT-IE/W

B

RY

E/W

B

RY

CVT/CC

CD

CVT/CC

17

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

18

PLCC---Uses

Voice communication Tele-control Tele-protection SCADA data from RTU

19

PLCC---Pros

Easy availability Cost effective Ease of operation & maintenance

20

PLCC--- Cons

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 CommunicationFiber 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..)

Two types of fibre- Multi 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

22

23

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

Cost effective for very high data transmission rates in a point-to-point configuration

24

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

25

VSAT CommunicationGeo-synchronous satellite

Earth Station

36,000 km

User site

26

VSAT(contd..) Very small aperture terminals (VSATs) used for

EMS/DMS For data comm. most frequently uses a shared

channel, to lower costs Communications routed through a third-party network

management center

UTILITY CONTROL CENTER

SHARED HUB

SATELLITE

VSATs

NETWORK MANAGEMENT

CENTER

27

VSAT (contd..) Various frequency bands:

C-band (4/6 GHz), Ku-band (12/14 GHz),Ka-band(30/20 GHz) Advantages

Near-universal coverage Good reliability Fast installation

Disadvantages Cost Transmission delays Blackout periods due to eclipses Attenuation in heavy rain (Ku band)

28

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

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 ProtocolsThe 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–60870–5-101Physical Layer :

Information bit : 8 bit

Stop bit : 1

Parity bit : Even

Data Link Layer

Standard Frame Format : FT 1.2

Maximum Frame Length : 255 bytes

Transmission Layer ( Station address field Length : 1 or 2 bytes )

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

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

Network Layer : Not defined as 870-5-101 is not IP based Selection of ASDUsASDU 1 : Single point informationASDU 2 : Single point information with time tagASDU 3 : Double point informationASDU 4 : Double point information with time tagASDU 9 : Measured value, Normalised valueASDU 10 : Measured value, Normalised value with time tagASDU 11 : Measured Value, Scaled valueASDU 12 : Measured value, Scaled value with time tagASDU 100 : Interrogation CommandASDU 103 : Clock Synchronisation CommandASDU 120 - 126 : File transfer Command

Master Slave

Request Message

Response Message

(User Data, Confirm Expected)

(Acknowledgment)

[P]

[P] = Primary Frame[S] = Secondary Frame

[S]

(Request User Data)

(Respond User Data or NACK)

[P]

[S]

Unbalanced

ICCP ProtocolAssociations

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 clientInformation 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 BlocksICCP 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 monitoringBlock 3 – Blocked Transfers Transfer Reports with Block dataBlock 4 – Information Message Information Message objects, IMTransfer Set objects Start Transfer

Stop Transfer Data Set Transfer Set Condition MonitoringBlock 5 – Device Control Device objects Select, Operate, Get Tag, Set Tag, Timeout, Local Reset, Success, Failure

Block 6 to Block 9 are not generally implemented

Communication Channel for Information flow

Sub-LDC

SLDC

RLDC

SLDC

Sub-LDC

RTU RTU

Wide Band /PLCC Commn

Wide Band Commn

Wide Band Commn(MW / FO)

RTU

Wide Band Commn

Wide Band Commn(MW / FO)

POWER GRID CORPORATION OF INDIA LTD

CONCEPTUAL SCADA SYSTEM DIAGRAM

RTU

TCT CTPT

T

RTU

TCT CTPT

T

CCOMMUNICATION FRONT END PROCESSOR

AREA LOAD DISPATCH CENTRE (ALDC)

Processor Interface level ( ALDC )

Communication level

Field Interface level

Data acquisition and

command actuation level

CR PANELS S/STN /POWER PLANTS

STATE LOAD AREA LOAD DISPATCH CENTRE (SLDC)

REGIONAL LOAD AREA LOAD DISPATCH CENTRE (RLDC)CONCEPTUAL DIAGRAM OF SCADA SYSTEM

IEC870 –5 –101

Supervisory level

ICCP LINKS X21 INTERFACE

MODEM

MODEM MODEM

MODEM

SCADA/EMS SYSTEM OVERVIEW

RTU

SCADA : Data communication architectureTFE

computer

Panel Multi-port Stallion Adapters

Panel multi-PortStallion adapters

Splitter

Modem

TFEcomputer

Modem

Modem

Modem

RTU

Modem

RTU

Modem Modem

Modem

TFEcomputer

TFEcomputer

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

Other Sites/ICCP Server

ICCP

CFE

S

M

M

RTU

CFE CFE

M M

M M

RTU

Normal RTU

CFE

Critical RTU

LAN-ALAN-A

LAN-BLAN-B

RTU Connectivity

Interface for RTUs reporting to Control Centre

Through PLCC LINK .RTU Location

RTU

Data (FSK)

Analog

PLCC

speech

PLCC

Data (FSK)

Analog

speech

Modem

Modem

Modem

Modem

Modem

Control Centre

Modem PLCC

Speech

RTU

Data(Fsk)

Analog

RTU Location Wideband Node

PLCCData(Fsk

)Analo

g

1

2

3

--

-

29

30

Primary

MuxSpeech

64 kbps Sub Mux

Require

Modem

RTU at Wideband Node

Radio

Radio

Radio

Link

Primary

Mux

1

2

3

--

28

29

30

Speech

Sub

Mux

Modem

Modem

Modem

Control Centre

4 x E-1

4 x E-1

Interface for RTU reporting to Control Centre via Tandem PLCC/Wideband Link & Wideband Links

RTU

RTU Through MICROWAVE

RTU Through FIBER OPTIC SYSTEM

SUBSTATION/ GEN STN SIDECONTROL CENTRE

RADIOTX / RXMUXCFE

OLTEMUXCFE

RADIOTX / RXMUX MUX RTU

OLTE MUX

Popular communication technologies in Indian Power systems:

Technology %Usage Power Line Carrier 50 Analog/digital Micro wave 15 Fiber Optic 30 GSM/GPRS <1 V-sat 5

WIDEBAND COMMUNICATION SYSTEM FOR EASTERN REGION

Barkote (Repater Shelter)

Ranchi

Tower #146 ( Repeater shelter)

Tower # 226( Repeater Shelter )

Kutra

Bargaon Tower # 313 ( Repeater Shelter )

SLDC

WEST BENGAL

ORISSAHatia

Belmuri

Burdwan

Mankar

MejiaWaria

Howrah

SLDC

Durgapur

CTPS

STPS

Bokaro-B

Budhipadar

Patna

Hajipur

Fatuha

Bodhgaya

Manpur

RajgirAtari

Biharshariff(BSEB)

Jamshedpur ( CS )

HVDC

Rourkela(CS )

Barchana

Naupada

Jajpur Town

Kamakhyanagar

Meramandali

Chainpal

Bhubaneswar

BIHAR

Jeypore(CS)

JayanagarSub LDC

Therubali

Narendrapur

Chandaka

SLDC

VidyutBhavan

Sub LDC

Sub LDC

Duburi

Mathkargola

Chandil

SLDC

LalganjMujaffarpur

SLDC

CPCC

Calcutta

ERSCC

Kalipahari

Microwave Link with Station :Microwave Repeater Station :Fibre Optic Link with Station :Monitoring Centre :

LEGEND:-

Biharshariff(CS)

JHARKHAND

Maithon-G

Kahalgaon (CS )U /

G

Bamra

Mendhasal

Tarkera

(Repeater )Akusingha

Kalyaneswari

DVC HQ

TSTPPUnder PDT

100M

80M

60M

BackupPDT

Farakka(CS)

Jeerat

Kasba

Malda(CS)

Siliguri (CS)

NBUSub LDC

India - Bhutan

border at 90 km

30M

BackupPDT

100M : RTCC link between Jey- Dgp For Indrvati & Jeypore RTU & Backup link

Backup64 KBPS

Backup64 KBPS

Backup64 KBPS

: Under Ground Fibre

WIDEBAND C OMMUNICATION NETWORK FOR NORTHERN REGION SC ADA SYSTEM

POWER SYSTEM OPERATION CORPORATION LIMITED Prepared by : SCADA Deptt.

Updated on : October, 2010

PUN J ABJ AMMU & K ASHMIR

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WIDEBAND COMMUNICATION NETWORK FOR NORTHERN REGION SCADA SYSTEM

VSAT / MEKSET L INK

NORTHERN REGIONAL LOAD DESPATCH CENTRE

45

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.

46

Future Trends 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.

47

Future Trends (contd..) Growing insistence on adherence to

communication standards. Possible application of cellular digital packet

data radio technologies.

Thank YouThank YouDevendra Kumar DGM,ERLDC