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

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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

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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

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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

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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

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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

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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

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~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?

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Backup Slides

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PLC Noise Scenarios

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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

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Noise Sources Noise Trace

Uncoordinated Interference Results

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General PLC NetworkHomogeneous PLC Network