Communications for Smart Grids
Hem Thukral
Research Officer
ISGF
Introduction
• Smart grid is a superposition of 2 networks
– The electrical network
• Generation
• Transmission
• Distribution
– The communications network
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Core/backbone
Backhaul/Wide Area Network (WAN)
Last mile/access/Neighbourhood Area Network (NAN)/ Field Area Network(FAN)
Home Area Network (HAN)
• Communication is the backbone of a smart grid
– 2-way communication is essential for the operation of a smart grid
– Monitoring and controlling the power flow in the grid
Topologies in Communications
• The topologies that are commonly used are
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Star
Mesh
Ring
Bus
Serial/line
• Selection of a topology depends on the application
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Wi-Fi: Star topology
Connecting smart meters to a data concentrator unit: mesh topology
Backbone networks using optical fiber: ring topology
Ethernet: Bus topology
Between an electronic meter and modem: serial topology
Use of Communications in a Smart Grid
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AMR
AMI
SCADA/DMS
SCADA/EMS
Wide Area Monitoring System (WAMS)
Substation Automation
Electric Vehicles
Distributed generation
Energy storage
Microgrids
Demand response
Redundant links for critical applications such as Distribution Automation and
Substation Automation
Automated Meter Reading (AMR)
Typical architecture of AMR
(Note: Communications is only ONE-WAY)
AMR is used extensively in R-APDRP for HT consumers, distribution transformers and
feeders. Both GSM and CDMA were used. It is reported that reliability is in the range
of 50-60%.
Advanced Metering Infrastructure (AMI)
Typical Architecture of AMI
COMMUNICATION IS 2-WAY
Advantages of communications in AMI
• Consumers could
– View their energy consumption accurately on a regular basis – informed consumer
– Manage loads via remote turn ON/OFF and managing total demand – SMART PHONE/IHD to turn
off!
– Save money from ToU tariffs by shifting non-priority loads
– Face reduced outages (SMART METER WILL CONVEY TO UTILITY)
• Utilities could achieve financial gains by
– Reading the meter remotely: REDUCED TRUCK ROLLS
– Managing the load curve by introducing demand response, ToU/ToD tariff, etc.
• No need to purchase expensive power at the last hour.
– Enabling faster restoration of electricity service after fault/events
• Outage detection easier using Smart Meter
– Detecting energy theft/pilferage on near real-time basis
– Billing and collection will be automatic
Supervisory Control And Data Acquisition
(SCADA) for DMS and EMS
Communications for SCADA(contd.)
• Monitoring
– Status
• Switch status, protection relay status, fault of FTU, flow detection,
momentary voltage drop etc.
– Measurement
• Voltage, current, active power, reactive power, power factor etc.
• Control
– Switch gear (open/close)
– Relay (in use/not in use)
Typical Architecture of SCADA
Wide Area Monitoring System(WAMS)
Typical architecture of WAMS
21 Sep 2012
WG <no> : <WG Title>
Communications for WAMS
–Voltage stability assessment
–Oscillation detection
–Post-fault analysis
–State estimation
–System state prediction
Other applications
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Substation Automation
Distributed Generation
Electric Vehicles
Energy Storage
Microgrids
Demand Response
Home Automation/Building Automation
Characteristics of communications for
smart grids
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High bandwidth
• AMI/AMR - low
• SCADA - high
Low latency
• AMI/AMR – low
• SCADA - high
High availability of network
High reliability
High level of security
• Meter – privacy of data
• SCADA – trip feeders using ONE
click of mouse
High level of scalability
Long range: choice of frequency!
Low power consumption
• Long technology life-cycle
• Compliant with regulations
• 865-867 MHz and 2.4 GHz
ONLY;
• Interoperable
• Low Total Cost of Ownership (TCO)
– Cost of infrastructure acquisition (towers,
PLC lines)
– Cost of communications media acquisition
(license fee)
– Operating cost
Potential Smart Grid Solutions
Wired options
• PLC (Narrowband and
broadband)
• Ethernet(co-axial cable,
twisted pair, optical fiber,
radio)
• RS-232
• RS-485
Wireless options
• Low Power RF (eg. 6LOWPAN, ZIGBEE,
proprietary)
– Operate mostly in SLEEP mode
• Cellular (GPRS, EDGE, 3G, HSPA, LTE,
WiMAX)
• Wi-Fi (data security ???)
• V-SAT
• Infra-Red
• Bluetooth
• Private point-to-point microwave links
• Private point-to-multipoint microwave
links
Wireless Spectrum – Global Scenario
For India, 2 MHz might be too less
• Millions of IEDs in a smart grids
• Billions of smart devices in a smart city
Spectrum for PLC – Global scenario
Region
Europe
Frequency band for PLC
CENELEC A: 3-95 KHz for power utilities
CENELEC B: 95-125 KHz for any application
CENELEC C: 125-140 KHz for in-home networking with mandatory
CSMA/CA protocol
USA
CENELEC D: 140-148.5 KHz Alarm and Security systems
10-490 KHz, and
2-30 MHz
Japan
China
10-450 KHz
3-500 KHz
Selection Criteria – some parameters
Criteria
Preferred Technologies
High Bandwidth
Optical fiber, BPL, WiMAX, 3G, HSPA, LTE, VSAT
Low Latency
DSL, optical fiber, Wi-Fi
High Reliability
Optical fiber, HSPA, LTE, V-SAT, DSL, Wi-Fi, RS-232, RS-485
High Security
Optical fiber, BPL, private RF Pt-to-MPt, WiMAX, V-SAT
Low Cost
Narrowband PLC, 6LoWPAN, ZigBee, Wi-Fi, Bluetooth, Infrared, GPRS, EDGE,
RS-232, RS-485
The selection of a technology will depend on the application
• For mission critical applications (such as Distribution Automation and
Substation Automation), security, latency and reliability will be the key. Cost will
not be considered as a parameter during selection.
• For non-critical applications (such as AMI), cost will be decisive.
Case Study (International)
Southern California Edison
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AMI – HAN: ZigBee
AMI – NAN: Proprietary RF mesh at 902 MHz
AMI – WAN: 3G
SCADA
Wide area connectivity: Optical fiber (mostly) + V-SAT (for remote locations)
Local Area connectivity: Proprietary solution using 902 MHz RF mesh network
Case Study (National)
MSEDCL
– AMR for R-APDRP: GPRS using modems for 58,000 meters (feeder + DT
+HT consumers)
– Meter reading using HHU
• ZigBee with modified SEP for 6.31 lac meters in dense urban areas
• InfraRed for 30 lac meters in rural areas
– Distribution Automation and Substation Automation
• Between field devices and RTU: RS-232
• Between RTU and control centre: leased line(optical fiber)
The Way Forward
• Un-licensed communication bands in India are:
– 865-867 MHz for low-power RFID devices (un-licenced in 2005)
– 2.4 GHz band
• Short range
• Interference: Wi-Fi, microwave ovens etc.
• Use of lower frequency bands (<865 MHz) could be considered
• Additional spectrum might be needed to cater to millions of connected
devices as part of the IoT
• National Optical Fiber Network (NOFN)
– Connecting all 33 kV substations USING OPTICAL FIBER for e-governance, e-learning
etc.
– Smart Grid applications could use this network
The Way Forward (contd.)
• To ensure interoperability, standards-based communication
technologies will be promoted
– IP-based technologies will gain traction in the market
• Use of proprietary solutions would reduce as these do not lead to
interoperability
• Standardization in India - BIS
– For formulation of standards in the field of Electronics and IT
• Electronics and IT Department (LITD)
– Sectional Committee LITD-10 (Power System Control and Associated
Communications) has Panels dedicated to smart grids
• AMI, Interoperability, CIM, Cyber Security, Digital Architecture
Conclusion
• Different geographic regions have different requirements and
constraints
– PLC might not be feasible in some areas where the wiring infrastructure is not
clean
– Low power RF mesh networks might not be feasible in densely populated
areas
• No ‘one’ communication technology will dominate the smart grid
– It will be a mix-and-match of different technologies
• Choice of technology will depend on the application
Conclusion (contd.)
• Performance (bandwidth, latency, reliability, security,
availability etc.) needs to be balanced with cost
• The Total Cost of Ownership (TCO) to be considered
– Cost of infrastructure acquisition
– Cost of communications media acquisition
– Operating cost
• The results of the 14 pilot projects will give us an indication on
what technology to use for large scale roll outs
Thank you..