0. POWERLINE COMMUNICATIONS FOR ENABLING SMART GRID APPLICATIONS
Task ID:
Prof. Brian L. Evans
Wireless Networking and Communications Group
Cockrell School of Engineering
The University of Texas at Austin
May 3, 2012

1. Principal Investigator:
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
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

2. Task Deliverables Date Tasks Dec 2010
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Task Deliverables
Date
Tasks
Dec 2010
Uncoordinated interference in narrowband PLC: measurements, modeling, and mitigation
May 2011
Single-transmitter single-receiver (1x1) PLC testbed
Dec 2011
Narrowband PLC channel and noise: measurements and modeling
On-going
Two-transmitter two-receiver (2x2) PLC testbed
Narrowband PLC noise mitigation

3. Smart Grid: Big Picture
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Smart Grid: Big Picture
Long distance communication : access to isolated houses
Real-Time : Customers profiling enabling good predictions in demand = no need to use an additional power plant
Micro- production: better knowledge of energy produced to balance the network
Demand-side management : boilers are activated during the night when electricity is available
Smart building : significant cost reduction on energy bill through remote monitoring
Any disturbance due to a storm : action can be taken immediately based on real-time information
Security features Fire is detected : relay can be switched off rapidly
Smart car : charge of electrical vehicles while panels are producing
Source: ETSI

4. Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Power Lines
Built for unidirectional flow of power and not for bidirectional communications
High Voltage (HV) 33 kV – 765 kV
Medium Voltage (MV) 1 kV – 33 kV
Low Voltage (LV) under 1 kV
Concentrator (Transformer)
Source: Électricité Réseau Dist. France (ERDF)

5. Powerline Communications
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Powerline Communications
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

6. Narrowband PLC Systems
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
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
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

7. Narrowband PLC Impulsive 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
Rx Receiver
Dominant in outdoor PLC
Increases with widespread deployment

8. Cyclostationary Noise Modeling
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Cyclostationary Noise Modeling
Measurement data from UT/TI field trial
Cyclostationary Gaussian Model [Katayama06]
Proposed model uses three filters [Nassar12]
Demux
Period is one half of an AC cycle
s[k] is zero-mean Gaussian noise
Adopted by IEEE P narrowband PLC standard

9. Asynchronous Noise Modeling
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Asynchronous Noise Modeling
Dominant Interference Source
Ex. Rural areas, industrial areas w/ heavy machinery
Middleton Class A Distribution [Nassar11]
Impulse rate l Impulse duration m
Homogeneous PLC Network
li = l, mi = m, g(di) = g0
Ex. Semi-urban areas, apartment complexes
Middleton Class A Distribution [Nassar11]
General PLC Network
li, mi, g(di) = gi
Ex. Dense urban and commercial settings
Gaussian Mixture Model [Nassar11]
Middleton Class A is a special case of the Gaussian Mixture Model.

10. Asynchronous Noise Sparse in time domain Learn statistical model
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Asynchronous Noise
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 x for same SNR
time
~10dB
~6dB
Transmission places 0-3 bits at each tone (frequency). At receiver, null tone carries 0 bits and only contains impulsive noise.

11. Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
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

12. Our PLC Testbed Hardware Software
Task Summary | Background | PLC Noise Modeling and Mitigation | PLC Testbed
Our 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

13. Our Peer-Reviewed Publications
Tutorial/Survey Article
M. Nassar, J. Lin, Y. Mortazavi, A. Dabak, I. H. Kim and B. L. Evans, “Local Utility Powerline Communications in the kHz Band: Channel Impairments, Noise, and Standards”, IEEE Signal Processing Magazine, Special Issue on Signal Processing Techniques for the Smart Grid, Sep
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.

14. Thank you for your attention…
Questions?

15. Backup Slides

16. Cyclostationary Noise Asynchronous Impulsive Noise
PLC Noise Scenarios
Background Noise
Cyclostationary Noise
Asynchronous Impulsive 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
time

17. Cyclostationary Noise
Noise Sources
Noise Trace

18. Uncoordinated Interference Results
Homogeneous PLC Network
General PLC Network