Last Mile Connectivity Challenges
in Smart Grid
Cigre Colloquium, Mysore, November 13-15
Chander B Goel
Texas Instruments India
1
Smart Grid Advantages
• Omits human Errors
• Reduced Man Power and
Quicker Billing
• Increase the resiliency of the
grid.
• Helps in implementation of
Dynamic Tariffing
• Helps to catch power theft
directly from power lines
• Helps to catch tampering of
Energy Meters
2
Smart Meter & Automated Meter Reading
Meter communicates via
wired or wireless interfaces
to the outside world. Level
of smartness depends on
the exact capabilities of
the meter
–1-way communication or
Automated Meter Reading
(AMR)
–2-way communication or
Advanced Metering
Infrastructure (AMI)
3
Expectations from AMR
• Reliability and sustained
connectivity
• Interoperability
• Security
• Ease of Installing and
Commissioning
• Lower Cost
4
AMR Technologies
• Wireless Technologies
–
–
–
–
Zigbee SE
6LowPAN
Wireless M-Bus
Wifi
• Wired technologies
– M-BUS with RS485
– Power Line
Communications
5
Choosing the ISM frequency band for LPRF
• Most of the countries
of the world allow
2.4GHz band free of
licensing
requirements but
there are limitations
with this band
because of lower
range and
interference.
• Most countries now
allow a sub 1 GHz
band for license free
use for AMR
applications
6
Comparing LPRF technologies
• Zigbee with SE
– Pros
• Mesh based self healing networks
• Mature specification. Interoperability guarenteed.
• Smart Energy profile available.
• Good for Home Area Network
– Cons
• Limited support for sub 1 GHz bands. 2.4GHz implementations limit
range.
• The stacks have a big footprint.
• 6LowPAN
– Pros
• The meters can be merged into internet.
• Standardization at RFC level.
– Cons
• Application layer is still open. Interoperability can be challenging.
7
Comparing LPRF technologies.
• Wireless M-Bus
– Pros
• Standardized in Europe as EN13757
• Operates at 868MHz. Can provide better range coverage.
– Cons
• Does not support mesh topology.
• Security is not inherently available in the specification.
• WiFi Direct
– Pros
• Ubiquotus. Mobile phones or Tablets can be used to read meters
– Cons
• The transceivers consume higher power.
• Limited range due to 2.4GHz frequency band.
8
Wired AMR - Power Line Communication
• Power Line Communications Refers to a Method of Narrow Band
Communications that uses the Existing Power Lines as the
Communication Medium
• Based on S-FSK or OFDM
High-Voltage Side
(110-380kV)
• Reduces System Cost
Utility Company
• Increases System Reliability
MediumVoltage Side
(10-30kV)
Backbone
Telecommunications
Network
Concentrator
MV router
Meter/modem
Transformer
Utility
Customer
Low-Voltage Side (110240V)
PLC Frequency Bands, Standards and Regulations
• PLC frequency bands in Europe
– Defined by the CENELEC:
• CENELEC-A (3 kHz – 95 kHz) are exclusively for
energy providers
Energy suppliers
• CENELEC-B, C, D bands are open
for end-user applications
– Bands A, B and D protocol layer is
defined by standards or proprietarily
A
defined
3–95 kHz
– Band C is regulated – CSMA access
Consumers
B
C
Future
D
• PLC frequency bands in USA
–
–
–
–
Single wide band – from 150 to 450 kHz
FCC band 10 kHz – 490 kHz
Access protocol defined by standard
HomePlug broadband: 2–30 MHz
• PLC frequency bands in Japan
– ARIB band 10 kHz – 450 kHz
• PLC frequency bands in China
– 3–90 kHz preferred by EPRI
– 3–500 kHz single-band not regulated
Standard/Proprietary
protocol
CSMA
Standard
protocol
Standards



Prime
G3
IEC 61334
Regulations



CENELEC
FCC
ARIB
10
PLC for Smart Grid AMI Worldwide
• Countries with PLC deployment for Smart Grid
–
–
–
–
Spain ( PRIME on CENELAC band)
France (G3 on CENELAC band)
Taiwan (G3 on FCC band)
Korea (IEEE P1901.2 on broadband)
• Countries with PLC pilots deployment for Smart Grid
–
–
–
–
–
–
China ( SFSK on EPRI band)
Mexico (PRIME on CENELAC band)
Japan (ITU-T G.9955 on ARIB band)
Turkey (G3 on CENELAC band)
Polland ( PRIME on CENELAC band)
USA (Propreitry for Home Plug)
11
Power Line Communication Challenges
• Frequency dependent attenuation
– Line Attenuation due to conductor material properties and branching
– Echos and interference due to Multipath propagation.
• Noise due to Loads
– Colored background noise due to Computers, Dimmers, Hair Dryers
– Narrowband Interference
– Synchronous periodic impulsive noise from Thyristor based DC power
supplies
– Asynchronous periodic impulsive noise due to switching transients
– Asynchronous impulsive noise in Industrial environments due to Arc welding
etc.
The latest PLC technology based on OFDM is looking
to be well immune to all the above factors.
12
Hybrid Networks - PLC/RF Combo
Sink
To backbone network
Wired
Wireless
1. Concrete wall: blocks radio, but penetrated by PLC
2. PLC blocked by noise,
use wireless to get around
Hybrid
Benefits:
• Robust network
• Smaller network
diameter
• Lower latency
A single noise source barely affect both networks
13
Simulation Platform for The Study of
Large Hybrid Sensor Networks
PLC
Node
RF
Node
A PLC Link
used by RPL
An RF Link
used by RPL
Extended COOJA simulator for the study of large networks with hybrid nodes
Hybrid Nodes Increase Robustness and
Shorten Network Diameter
Two RF nodes replaced
by hybrid nodes
Extended RPL and MAC protocols for networks with hybrid nodes
Open Challenges in AMR
• Sustained Connectivity – Guarenteed ??
• Isolation of PAN – Commissioning Challenge.
• AMR Standards and Technologies – Matured ?? Proven ??
• Field Software Upgradability – Should be mandatory.
• Security – Guarenteed ??
• Database management and maintenance – Expertise to be developed.
16
Thank You
17