Smart Grid Communications
Ketan Rajawat
IIT Kanpur
Smart Microgrids
“Building the smart grid.” The Economist [US] 6 June 2009: 16(US).
Role of communications
SG
Communication
Applications
AMI
In-Home Displays
to Meter
SCADA
DR signals from
utility centres to
meters
Connect/Disconnect
signal to meters
Switches
communicate with
one other & central
office
Voltage regulators
communicate with one
other & central office
Conservation Voltage
Reduction
Network needs for diverse applications
The bandwidth/latency/reliability
requirements vary widely
Electric Vehicle (>20Mbps):
Distributed generation
Asset monitoring
Substation automation
Distribution automation
Grid monitoring
Demand Response (250 kbps)
AMI
Smart Grid Applications
Generation Transmission & Distribution(a) Reclosers
(b) Capacitor Banks (poles)
(c) SCADA
(d) Volt/VAR control
(e) Energy storage
(f) Outage management
(g) Distributed Generation control
(h) RTU
Advanced Meters(a) Residential Electric
(b) C&I Electric
(c) Gas meters
Energy Efficiency and Demand Response(a) Thermostats
(b) In-home displays
(c) Load controllers
(d) Consumer products
(e) PHEVs
Considerations
6 6
Data Delivery
CriticalityNetwork LatencySecurity
Provide different
levels of data
delivery criticality
depending on the
needs of the
application
Criticality levels
based on data loss
Supports varied
latency requirements
messages
communicated
between various
points within the
smart grid
Secure information
storage and
transportation for
billing purposes and
grid control
Avoidance of cyber
attacks
66
ScalabilityReliability
Scalability with the integration of
advanced web services, reliable
protocols with advanced functionalities
Facilitate operation of power grid
Reliable for
successful and
timely exchange of
messages
Reliability affected
by time-
out/network/resourc
e failures
Smart Grid Requirements
Performance(a) BW: bps to Mbps (usage pattern of PHEVs)
(b) latency: ms (demand resp for grid in distress) to sec
(c) uptime: 90% to 99.9999%
(d) Scalability: as many as 10 dev/home to millions of homes (mostly ignored earlier)
(e) range: meters (NAN) to km (home to substation)
Standards(a) Security: AMI-SEC, NERC CIP, NIST 800-53/800-82
(b) Application protocols: DNP3, IEC 60870/TASE; IEC 61850; IEC 61968; ANSI
C12.19/C12.22; SEP; SNMP
(c) Comm: Ipv4/6, ZigBee, HomePlug, 802.15.4
(d) Performance: IEEE1646
Future proof: Meters last 20-30 years. Electronics changes every 2-3 years.
Interoperation?
Ho QD, GaoY, Rajalingham G, Le-Ngoc T. Wireless Communications Networks for the Smart Grid. Springer;
2014 Sep 19.
Traffic and Required QoSsTraffic Types Description Bandwidth Latency
AMI Networks
Meter Reads Meters report energy consumption (Ex: the 15-min interval reads
are usually transferred every 4 hours)
Up to 10kbps 2 to 10sec
Demand Response (DR) Utilities to communicate with customer devices to allow customers
to reduce or shift their power use during peak demand periods
Low 500ms ~ min
Connects and Disconnects Connects/disconnect customers to/from the grid Low A few 100ms, few min
Substation Networks
Synchrophasor The major primary measurement technologies deployed
for Wide-Area Situational Awareness (WASA)
A few 100kbps 20ms to 200ms
Substation SCADA 4-sec interval polling by the master to all the intelligent
electronic devices inside the substation
10 to 30kbps 2 ~ 4sec
Inter-substation
Communications
Emerging applications such as Distributed Energy Resources (DER)
might warrant GOOSE communications outside substation
-- 12ms ~ 20ms
Surveillance Video site surveillance A few Mbps A few sec
Distribution Network
Fault Location, Isolation and
Restoration (FLIR)
To control protection/restoration circuits 10 to 30kbps A few 100ms
Optimization VOLT / VAR optimization and power quality optimization
on distribution networks
2 ~ 5Mbps 25 ~ 100ms
Workforce Access Provides expert video, voice access to field workers 250kbps 150ms
Asset Management For predictively and pro-actively gathering and analyzing
non-operational data for potential asset failures
-- --
Microgid
Protection To response to faults, isolate them and ensure loads
re not affected
-- 100ms ~ 10sec
Operation Optimization Monitors and controls the operations of the whole MG in order to
optimize the power exchanged between the MG and the main grid
-- 100ms ~ min
Communication requirementsApplications Security Bandwidth Reliability Latency
Advanced Metering
Infrastructure
High 14-100 kbps per
node
99.0-99.99% 2000 ms
AMI Network Management High 56-100 kbps 99.00% 1000-2000 ms
Automated Feeder Switching High 9.6-56 kbps 99.0-99.99% 300-2000 ms
Capacitor Bank Control Medium 9.6-100 kbps 96.0-99.00% 500-2000 ms
Charging Plug-In Electric
Vehicles
Medium 9.6-56 kbps 99.0-99.90% 2000 ms - 5
min.
Demand Response High 56 kbps 99.00% 2000 ms
Direct Load Control High 14-100 kbps per
node
99.0-99.99% 2000 ms
Distributed Generation High 9.6-56 kbps 99.0-99.99% 300-2000 ms
Distribution Asset
Management
High 56 kbps 99.00% 2000 ms
Emergency Response Medium 45-250 kbps 99.99% 500 ms
Fault Current Indicator Medium 9.6 kbps 99.00-
99.999%
500-2000 ms
In-home Displays High 9.6-56 kbps 99.0-99.99% 300 -2000 ms
Meter Data Management High 56 kbps 99.00% 2000 ms
Source: M. Kuzlu, M. Pipattanasomporn and S. Rahman, "Communication network requirements for major smart grid applications in HAN,
NAN and WAN", Computer Networks, vol. 67, pp. 74-88, 2014.
Multi-Tiered Architecture
Neighbor Area Network (NAN) Home Area Network (HAN)
Power Generation Power Transmission Grid Power Distribution Grid Power Consumption
Smart
MeterSubstationSubstation Customer
Microgrid
Microgrid
(a) Power System Layer
(b) Communications Layer
WirelessBackhaul
BaseStation
Control Center
Wired Backhaul
Network
Wide Area Network (WAN)
Smart
Meter
Data Aggregation
Point (DAP)
Electric Vehicle
Solar EnegyWind Enegy
Non-renewable Enegy
Concentrator Smart
Home
Device
The overall layered architecture of SG
Mohammad S. Obaidat, Alagan Anpalagan, and Isaac Woungang. 2012. Handbook of Green Information and Communication Systems (1st ed.). Academic Press.
High-Level Overview
External
HAN
Meter
LAN
Enterprise
WAN
Meter
Collector
Metering System
Portal
Normal
ProgramCritical
Peak EventEmergency
Stage 1Emergency
Stage 2 Current
Temp
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AY
Retailers
Aggregators
Regulators
Customers
Providers
MDMS
CIS/Billing
OMS
WMS
EMS/DMS
Routers
Towers
Ground Stations
Repeaters
Rings
Relays
Modems
Bridges
Access Points
Insertion Points
Thermostats
Pool Pumps
Field Tools
PCs
Building Automation
Internet Protocols
World-Wide Web
ebXML
IEC 60870-6 ICCP
IEC 61970
IEC 61968
Web Services
Multispeak
Message Buses
SONET, WDM, ATM
MPLS
Frame Relay
Satellite
Microwave
IEC 61850
DNP3
WiMAX
BPL / PLC
Wireless Mesh
ADSL
Cellular
Cable (DOCSIS)
ZigBee
WiFi
LonWorks
BACnet
HomePlug
OpenHAN
Example
Members
Example
Technologies
Neighborhood Area Networks (NANs)
Gathers a huge volume of various types of
data and distributes important control
signals from and to millions of devices
installed at customer premises
The most critical segment that connects
utilities and customers in order to enable
primarily important SG applications
Characteristics of NAN
To support a huge number of devices that
distribute over large geographical areas
Must be scalable to network size and self-
configurable
Heterogeneous and location-aware
Link condition and thus network connectivity
are time-varying due to multipath fading,
surrounding environment, harsh weather,
electricity power outage, etc.
Characteristics of NAN
Deployed outdoor, thus must be robust to node
and link failures
Carries different types of traffic that require a
wide range of QoSs
Needs QoS awareness and provisioning
Mainly supports Multi-Point-to-Point (MP2P)
and Point-to-Multiple-Point (P2MP) traffic
Very vulnerable to privacy and security
Home Area Network (HAN)
Source: Mentor Graphics
HAN Portal Options
meter-as-portal: NAN connects to meter. meter
connects to HAN (using wifi or zigbee), meter has 2
radios, since meter does not change, this is
problematic: not future proof
HAN-device-as-portal: deploy as you go, thermostat as
gateway, device and meter need not be close togather,
U-SNAP: usb for smart-
grid devices, plug into
thermostat, protocol-
agnostic, multiple usnap on
a gateway device
multiple NANs at the same
time
Communication Technologies
Wireless
◦ Zigbee (IEEE802.15.4)
◦ Z-wave (proprietary)
◦ WiFi (IEEE802.11)
◦ 3G cellular
◦ 4G: LTE/LTE-A
◦ 802.22 (white space)
Wired
◦ Power Line Communications
◦ Fiber Optical Comm, Ethernet
Challenges
Wireless channels are
◦ Prone to interference (crowded bands)
◦ lower bandwidth than wired communication
technologies
◦ Low penetration through concrete
construction
◦ Limited Range
◦ Impact of power lines on wireless comm?
IEEE802.15.4 Zigbee
Zigbee is a short-range, low-data rate, energy-efficient wireless protocol
Zigbee utilizes
◦ 16 channels in the 2.4GHz ISM band worldwide
◦ 13 channels in the 915MHz band in North America
◦ one channel in the 868MHz band in Europe
◦ It supports data rates of 250 kbps, 100kbps, 40 kbps, and 20 kbps
ZigBee Smart Energy Profile (SEP) aims to support the needs of smart metering and AMI, and provide communication among utilities and household devices
Zigbee pros and cons
Low cost, inexpensive devices
Self-organizing, secure, reliable, scalable
Short range and does not penetrate
structures, low data rate
Deployment mainly in HANs
Using 802.15.4 in NAN?
802.15.4 (ZigBee) in NAN: many benefits
many suppliers
ICs in many applications
dependable long-term component supply from
major semiconductor houses
optimized radio performance (many years of
development, can control many parameters)
intrinsic immunity from interference: DSSS, co-
existence with other 2.4 GHz
250kbps
IEEE802.11 WiFi
Data rate of IEEE 802.11 standards range from 1 Mbps to 100 Mbps◦ It operates in the 2.4 GHz ISM band
Low cost, widely used, stable and mature
Small coverage, short distances, unsecure
Wi-Fi is targeting Home Area Networks (HAN), Neighborhood Area Networks (NAN) and Field Area Networks (FAN) in the smart grid
Wi-Fi is already being used for municipal-scale network infrastructures outdoors
Z-wave
Z-Wave is a proprietary, short-range, low-data rate wireless RF mesh networking standard
Z-wave uses the 908MHz ISM band in the Americas, and its data rate is 40kbps
Z-wave provides connectivity for devices such as; lamps, switches, thermostats, garage doors.◦ Z-wave can be employed in the HAN segment of
the smart grid
LTE and LTE-Advanced
The peak data rates for LTE is around 300Mbps at the
downlink and 80Mbps at the uplink with 20MHz channel
bandwidth and 4x4 MIMO antennas
◦ LTE-A’s targeted peak downlink transmission rate is 1Gbps and
the uplink transmission rate is 500Mbps
A typical LTE cell has a diameter of 4km
◦ By relaying technique, range can be extended
LTE and LTE-A
Low latency, low power consumption
Utility must rent the infrastructure
High cost of equipment
Proposed for
◦ Backhaul, SCADA
◦ Demand response
◦ Video site surveillance
IEEE802.22 Cognitive Radio
Cognitive Radio (CR) provides access to unlicensed users to the spectrum that is not utilized by licensed users◦ A CR has the ability to sense unused spectrum, use it and
then vacate as soon as a licensed user arrives
The bands that are planned to be used by 802.22 are the UHF/VHF bands between 54 and 862 MHz and their guard bands
Power Line Communications
Power Line Communications (PLC) use the low voltage power lines as the communication medium
PLC has been already used by some utilities for load control and remote metering◦ It can be integrated to the smart metering system
since the power lines already reach the meter
As the PLC does not have external cabling cost, it is considered to be convenient for HANs, NANs and FANs in the smart grid
IEEE P1901/Broadband PLC
BPL has high data rates exceeding
100Mbps using frequencies below
100MHz
P1901 workgroup has selected two PHY
layers for the standard
◦ Wavelet OFDM-based PHY
◦ FFT OFDM-based PHY
These PHY techniques aim to improve
the communications over noisy PLC
Challenges: PLC
Powerline communications suffer from
◦ Noisy channel conditions
◦ Channel characteristics that vary depending
on the devices plugged in (switched on)
◦ Electromagnetic interference (EMI) due to
unshielded power lines
◦ Poor isolation among units
◦ Improper Wiring
Fiber Optic Communications
Fiber optics is already used in the power grid to connect utility head offices and substations
Fiber optics is not impacted by electromagnetic interference◦ Ideal for the high voltage operating environment
◦ Major drawback of fiber is high deployment cost
Optic Ethernet can be also utilized in the smart grid
It is also possible to employ a combination of the wireless and wired communication technologies in the smart grid
Comparison of various technologies
Wireless Technologies for Smart GridTechnology Advantage Disadvantage Application
Zigbee (IEEE 802.15.4, ZigBee
Alliance)
Low-cost, low power, wireless
mesh standard for wireless
home area networks (WHANs)
or wireless personal area
networks (WPANs)
Very low cost - inexpensive consumer devices;
Low power consumption - years of battery life;
Self- organizing, secure, and reliable mesh
network; Network can support a large number
of users; Smart energy profile for HANs is
available
Very short range; Does not penetrate structures
well; Low data rates; Developers must join
ZigBee Alliance
HANs for energy
management and
monitoring;
Unlikely to be used
in NANs
Wi-Fi (IEEE 802.11b/g/n)
Indoor wireless local area
networks (WLANs), wireless
mesh networks
Low-cost chip sets - inexpensive consumer
devices; Widespread use and expertise; Low-cost
application development; Stable and mature
standards
Does not penetrate cement buildings or
basements; Small coverage and short distances
limit wide spread use; Security issues with
multiple networks operating in same locations
Could be used for
HANs, MGANs,
and NANs
3G Cellular (UMTS,
CDMA2000, EV-DO, EDGE)
Wide-area wireless networks
for voice, video, and data
services in a mobile
environment
Expensive infrastructure already widely deployed,
stable and mature; Well standardized; Equipment
prices keep dropping; Readily available expertise
in deployments; Cellular chipset very
inexpensive; Large selection of vendors and
service providers
Utility must rent the infrastructure from a
cellular carrier for a monthly access fee; Utility
does not own infrastructure; Technology is in
the transition phase to LTE deployment; Public
cellular networks not sufficiently stable/secure
for mission critical/utility applications; Not well-
suited for large data/high bandwidth applications
AMI Backhaul, Field
Area Network
(FAN)
LTE
Enhancements to 3G Universal
Mobile Telecommunications
System (UMTS) mobile
networking, providing for
enhanced multimedia services
Low latency, high capacity; Fully integrated with
3GGP, compatible with earlier 3GPP releases;
Full mobility for enhanced multimedia services;
Carrier preferred protocol; Low power
consumption
Utility must rent the infrastructure from a
cellular carrier for a monthly access fee; Utility
does not own infrastructure; Not readily
available in many markets/still in testing phases in
others; Equipment cost high; Vendor
differentiation still unclear; Lack of expertise in
designing LTE networks; Utilities’ access to
spectrum
AMI Backhaul,
SCADA Backhaul,
Demand Response,
FAN, Video
Surveillance
Interoperability
Incompatibility
Inability of two or
more devices to
work together
1
Coexistence Interconnectability Interworkability
InteroperabilityInterchangeability
Ability of two or more
devices to operate
independently of one
another at the same
communications network
2Ability of two or more
devices to operate with
one another using the
same communication
protocols
3Ability to support
transfer of device
parameters between
devices having the same
communication interface
4
Ability of two or more
devices to work together
in one or more
distributed applications
5Ability of two or more devices to work
together in one or more distributed
applications using the same communications
protocol and interface
6
Integrated Network Monitoring System
Centrally monitor various networks a
utility
Provide a complete end-to-end view of
the system health and fault and
performance data from different
network elements.
Incorporates rules-based management
functions to be followed for network
issue across the system
Integrated Network Monitoring System Benefits
Meet QoS expectations through end-
to-end service visibility
Optimize network resources to
improve performance and quality
Cut network operating costs
Support network planning process to
roll out more Smart Grid network
services
Expedite Smart Grid network
diagnostics
Existing work by: NIST-SGIP, Bureau of Indian Standards, IEEE Smart Grid Standards
Internet Protocol
IP Functions
Changing and growing with industry: Ability to add a capability such as anew application without having to change IP itself
Connecting large number of devices: IPv6 offers straightforward addressingand routing for a huge network such as the smart grid
Maintaining Reliability: Tools and applications to help manage the networkand maintain reliability
Connecting multiple types of systems: Identify both source and receivingsystem establishing a two-way communication link
Ensuring Security: Tools enabling securing and managing the transport ofdata
Transmitting data over multiple media: Run over any link layer networkproviding a common and flexible way to use and manage a network composedof disparate parts
Providing smooth migration: Provides a way to migrate in phases frommultiple monitoring and control networks to a single converged networkwithout disrupting service
Communication Enabled Smart Grid Applications
Direct Load Control (DLC)
Wireless sensor network (WSN)-based
demand management
iPower
Sensor web services for energy management
Machine-to-machine (M2M) communications
based demand management
Energy saving applications on appliances
Electric vehicle demand management
Direct Load Control (DLC)
DLC means passing the control of several appliances to the utility or an aggregator◦ Appliances that can be remotely controlled are pool
pumps and the heating/cooling appliances
◦ A pilot study in Australia has shown that cycling air conditioners have resulted in 17% of peak load reduction
DLC requires simple communications between the consumers and the utility◦ Utility commands can be delivered to the customers
through smart meters
Zigbee or one of the PLC standards can be a suitable option for DLC
Wireless Sensor Network (WSN)-
based Demand Management in-Home Energy Management (iHEM) is a non-
intrusive, interactive demand management
scheme
Energy Management Unit and appliances
communicate wirelessly over the WSN
iHEM aims to shift consumer demands to off-
peak hours
Unlike, DLC, iHEM
suggests convenient start
times for the appliances
iPower
Intelligent and Personalized energy conservation system by wireless sensor networks:◦ Implements an energy conservation application for multi-
dwelling homes and offices
◦ Employs a WSN, a control server, power-line control devices and user identification devices
◦ Sensor nodes are deployed in each room and they monitor the rooms with light, sound and temperature sensors
◦ They form a multi-hop WSN and send their measurements to the gateway when an event occurs
iPower combines wireless and power line communication technologies
Sensor web services for energy
management
Energy management application is a suit of three energy management modules:◦ Enables users to learn the energy consumption of
their appliances while they are away from home
◦ Load shedding application for the utilities. Load shedding is applied to the air conditioning appliances when the load on the grid is critical
◦ Application for energy generating customers. Customers can monitor and control the amount of energy stored and energy sold back to the grid while they are away from home
These applications utilize sensor web services
Machine-to-machine (M2M) communications
based demand management
M2M communications have been implemented in the Whirlpool Smart Device Network (WSDN)
WSDN consists of HAN, the Internet and AMI
WSDN utilizes several technologies together◦ Wi-Fi connects the smart appliances and forms the HAN
◦ ZigBee and PLC connect the smart meters in the AMI
◦ Broadband Internet connects consumers to the Internet
It enables remote access to appliance energy consumption
It also provides load shedding capabilities to utilities during critical peaks
Energy saving applications on
appliances
An appliance-to-appliance communication protocol for energy saving applications
Energy management protocol allows consumers to set a maximum consumption value
Based on this threshold, the residential gateway is able to turn off the appliances that are in standby mode once these limits are exceeded
Electric vehicle demand management
Home Gateway and Controller (HGC)
communicates with the PHEV
◦ Controls its charging and discharging profile based on
Status of the roof-top solar power generation unit
Demands of the smart appliances
HGC also
communicates with the
other HGC devices in
the neighborhood and
coordinates PHEV loads
Smart Grid Standards
Inter-operability: “the ability of two or more systems or components to exchange information and to use the information that has been exchanged”
The overall SG system is lacking widely accepted standards
Standards Development Organizations (SDOs):
◦ National Institute of Standards and Technology (NIST),
◦ American National Standards Institute (ANSI),
◦ International Electrotechnical Commission (IEC),
◦ Institute of Electrical and Electronics Engineers (IEEE),
◦ International Organization for Standardization (ISO), International Telecommunication Union (ITU),
◦ etc.
Alliances: ZigBee Alliance, Wi-Fi Alliance, HomePlugPowerline Alliance, Z-Wave Alliance, etc.
Representative SG Standards
C12.18
C12.19
C12.22
M-Bus
Zigbee
Wi-Fi
SAE J2293
SAE J2836
SAE J2847
IEEE P2030
BACnet
OpenADR
DRBizNet
IEC 61850
DNP3
Distributed Energy
Resources
IEC 61400-25
IEEE 1547
Commercial user
Residential user PHEV
Wind farm
IEC 61850-7-420
Smart
meter
Wi-Fi
SUN
3G/4G Cellular
Substation
Wide Area Network
Neighbor Area Network
3G/4G
Cellular Wi-Fi
SONET
WiMAX
IEC 61850
DNP3
CIMControl center
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