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

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Stage 1Emergency

Stage 2 Current

Temp

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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