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POWERLINE COMMUNICATIONS FOR ENABLING SMART GRID APPLICATIONS
Task ID: 1836.063
Prof. Brian L. EvansWireless Networking and Communications Group
Cockrell School of EngineeringThe University of Texas at Austin
bevans@ece.utexas.edu
http://www.ece.utexas.edu/~bevans/projects/plc
May 3, 2012
2
Task Description:Improve powerline communication (PLC) bit rates for monitoring/controlling applications for residential and commercial energy uses
Anticipated Results: Adaptive methods and real-time prototypes to increase bit rates in PLC networks
Principal Investigator:Prof. Brian L. Evans, The University of Texas at Austin
Current Students (with expected graduation dates):Ms. Jing Lin Ph.D. (May 2014)Mr. Yousof Mortazavi Ph.D. (Dec. 2012)Mr. Marcel Nassar Ph.D. (Dec. 2012)Mr. Karl Nieman Ph.D. (May 2014)
Industrial Liaisons:Dr. Anand Dabak (TI), Mr. Leo Dehner (Freescale), Mr. Michael Dow (Freescale), Mr. Frank Liu (IBM) and Dr. Khurram Waheed (Freescale)
Starting Date: August 2010
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Task Deliverables
3
Date Tasks
Dec 2010Uncoordinated interference in narrowband PLC: measurements, modeling, and mitigation
May 2011Single-transmitter single-receiver (1x1) PLC testbed
Dec 2011Narrowband PLC channel and noise:measurements and modeling
On-goingTwo-transmitter two-receiver (2x2) PLC testbedNarrowband PLC noise mitigation
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Smart Grid: Big Picture
4
Smart car : charge of electrical vehicles while
panels are producing
Long distance communication : access to isolated
houses
Real-Time : Customers profiling
enabling good predictions in
demand = no need to use an additional
power plant
Any disturbance due to a storm : action can be
taken immediately based on real-time
information
Smart building : significant cost
reduction on energy bill through remote
monitoring
Demand-side management :
boilers are activated during the night
when electricity is available
Micro- production:
better knowledge of
energy produced to balance the
network
Security features Fire is detected : relay can be switched
off rapidly
Source: ETSI
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Power Lines
Built for unidirectionalflow of power and notfor bidirectionalcommunications
5
Medium Voltage (MV)
1 kV – 33 kVLow Voltage (LV)
under 1 kV
High Voltage (HV)
33 kV – 765 kV
Source: Électricité Réseau Dist. France
(ERDF)
Concentrator
(Transformer)
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Powerline Communications
6Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Category Freq. Band Bit Rate Applications
Ultra narrowband 0.3 – 3.0 kHz ~100 bps• Automatic meter reading• Outage detection• Voltage monitoring
Narrowband 3 – 500 kHz ~500 kbps• Device-specific billing• Smart energy management
Broadband 1.8 – 250 MHz ~200 Mbps • Home area networks
Narrowband PLC systems• Bidirectional communication over
MV/LV lines between local utility and customers
• Industry standards: G3, PRIME• International standards: G.hnem,
IEEE P1901.2
Narrowband PLC Systems• Problem: Non-Gaussian impulsive noise is primary
limitation to PLC communication performance yet traditional communication system design assumes noise is Gaussian
• Goal: Improve communication performance in impulsive noise (i.e. increase bit rate and/or reduce error rate)
• Approach: Statistical modeling of impulsive noise• Solution: Receiver design to mitigate impulsive noise
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Parametric Nonparametric
Listen to environment No training necessary
Find model parameters Learn statistical model from communication signal structure
Use model to mitigate noise Exploit sparsity to mitigate noise
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Narrowband PLC Impulsive Noise
Cyclostationary Noise Asynchronous Noise
Example: rectified power supplies Example: uncoordinated interference
8Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Increases with widespread deploymentDominant in outdoor PLC
Rx Receiver
Cyclostationary Noise Modeling
9
Measurement data from UT/TI field trial
Cyclostationary Gaussian Model [Katayama06]
Proposed model uses three filters [Nassar12]
Adopted by IEEE P1901.2 narrowband PLC standard
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Period is one halfof an AC cycle
Demux
s[k] is zero-mean Gaussian noise
Asynchronous Noise Modeling
10
Ex. Rural areas, industrial areas w/ heavy machinery
Dominant Interference Source
Middleton Class ADistribution [Nassar11]
Homogeneous PLC Network
Ex. Semi-urban areas, apartment complexes
General PLC Network
Ex. Dense urban and commercial settings
Gaussian MixtureModel [Nassar11]
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Middleton Class ADistribution [Nassar11]
Middleton Class A is a special case of the Gaussian Mixture Model.
Impulse rate lImpulse duration m
li = , l mi = m, (g di) = g0
li, mi, (g di) = gi
-10 -5 0 5 10
10-5
10-4
10-3
10-2
10-1
SNR (dB)
Sym
bol E
rror
Rat
e
No cancellationSBL w/ null tonesSBL w/ all tones
• Sparse in time domain
• Learn statistical model• Use sparse Bayesian
learning (SBL)• Exploit sparsity in time
domain [Lin11]
• SNR gain of 6-10 dB• Increases 2-3 bits per tone
for same error rate - OR -• Decreases bit error rate by
10-100x for same SNR
Asynchronous Noise
11
~10dB
~6dB
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
time
Transmission places 0-3 bits at each tone (frequency). At receiver, null tone carries 0
bits and only contains impulsive noise.
Our PLC Testbed• Quantify application performance vs. complexity tradeoffs
• Extend our real-time DSL testbed (deployed in field)• Integrate ideas from multiple narrowband PLC standards• Provide suite of user-configurable algorithms and system settings• Display statistics of communication performance
• 1x1 PLC testbed (completed)• Adaptive signal processing algorithms• Improved communication performance 2-3x on indoor power lines
• 2x2 PLC testbed (on-going)• Use one phase, neutral and ground• Goal: Improve communication performance by another 2x
12Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Our PLC Testbed
13Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Hardware Software
• National Instruments (NI) controllers stream data
• NI cards generates/receives analog signals• Texas Instruments (TI) front end couples to
power line
• Real-time system runs transceiver algorithms
• Desktop PC running LabVIEW is used as an input and visualization tool to display important system parameters.
1x1 Testbed
Our Peer-Reviewed PublicationsTutorial/Survey Article• M. Nassar, J. Lin, Y. Mortazavi, A. Dabak, I. H. Kim and B. L. Evans, “Local Utility
Powerline Communications in the 3-500 kHz Band: Channel Impairments, Noise, and Standards”, IEEE Signal Processing Magazine, Special Issue on Signal Processing Techniques for the Smart Grid, Sep. 2012.
Conference Publications• M. Nassar, A. Dabak, I. H. Kim, T. Pande and B. L. Evans, “Cyclostationary Noise
Modeling In Narrowband Powerline Communication For Smart Grid Applications”, Proc. IEEE Int. Conf. on Acoustics, Speech, and Signal Proc., Mar. 2012, Kyoto, Japan.
• M. Nassar, K. Gulati, Y. Mortazavi, and B. L. Evans, “Statistical Modeling of Asynchronous Impulsive Noise in Powerline Communication Networks”, Proc. IEEE Int. Global Communications Conf., Dec. 2011, Houston, TX USA.
• J. Lin, M. Nassar and B. L. Evans, “Non-Parametric Impulsive Noise Mitigation in OFDM Systems Using Sparse Bayesian Learning”, Proc. IEEE Int. Global Communications Conf., Dec. 2011, Houston, TX USA.
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Thank you for your attention…
Questions?
15
Backup Slides
16
PLC Noise Scenarios
17
Background Noise Cyclostationary Noise AsynchronousImpulsive Noise
• Spectrally shaped noise• Decreases with frequency• Superposition of lower-
intensity sources• Includes narrowband
interference
• Cylostationary in time and frequency
• Synchronous and asynchronous to AC main frequency
• Comes from rectified and switched power supplies (synchronous), and electrical motors (asynchronous)
• Dominant in narrowband PLC
• Impulse duration from micro to millisecond
• Random inter-arrival time• 50dB above background
noise• Caused by switching
transients and uncoordinated interference
• Present in narrowband and broadband PLC
0 100 200 300 400 500-150
-100
-50
Frequency (kHz)
time
Cyclostationary Noise
18
Noise Sources Noise Trace
Uncoordinated Interference Results
19
General PLC NetworkHomogeneous PLC Network
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