Powerline Communications for Enabling Smart Grid Applications
description
Transcript of Powerline Communications for Enabling Smart Grid Applications
SRC GRC Annual ReviewMarch 8, 2011
Powerline Communicationsfor Enabling Smart Grid Applications
Prof. Brian L. EvansWireless Networking and Communications
GroupThe University of Texas at Austin
Task ID 1836.063
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Task Description:Increase powerline communication (PLC) data rate for better monitoring/control applications for residential and commercial energy uses
Anticipated Results: Adaptive methods and real-time prototypes to increase bit-rates in PLC networks
Primary Investigator:Prof. Brian L. Evans, The University of Texas at Austin
Current Students Current StatusMs. Jing Lin Ph. D (expected graduation in May 2014)Mr. Yousof Mortazavi Ph. D (expected graduation in Dec. 2013)Mr. Marcel Nassar Ph. D (expected graduation in May 2012)
Industrial Liaisons:Dr. Anand Dabak (Texas Instruments), Mr. Leo Dehner (Freescale), Mr. Michael Dow (Freescale) and Mr. Frank Liu (IBM)
Starting Date: August 2010
Task Deliverables
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Data and algorithms for receiver synchronization, channel measurements and modeling, and asynchronous impulsive noise mitigation (12/2010)
Single-transmitter single-receiver (1x1) powerline communication system testbed: software package and documentation (5/2011)
Data and algorithms for multichannel transmission for a three-transmitter single-receiver (3x1) powerline communication system (12/2011)
Three-transmitter single-receiver (3x1) powerline communication system testbed: software package and documentation (5/2012)
Data and algorithms for crosstalk cancellation and low-power medium access control scheduling algorithms (12/2012)
Three-transmitter three-receiver (3x3) powerline communication system testbed: software package and documentation (5/2013)
Executive Summary Accomplishments
Investigated PLC standards Literature survey on powerline channel/noise characterization Built software and hardware framework for the PLC testbed Simulated receiver frame synchronization using chirp signal
Current work Asynchronous impulsive noise mitigation algorithms
Future directions Smart hand-shaking mechanisms between transmitter and receiver on the
best sub-band (with high SNR) for transmission Algorithms for synchronous impulsive noise mitigation Noise and channel modeling and analysis
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Background: Smart Grid Big Picture
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: ETSI5
Background: Voltage Levels in Grid
Medium-VoltageLow-
Voltage
High-Voltage
Source: ERDF
6“Last mile” PLC communications on low/medium voltage line
Concentrator
Motivation for “Last Mile” PLC
Source: Powerline Intelligent Metering Evolution (PRIME)
Alliance Draft v1.3E
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Concentrator controls medium to subscriber meters Similar to wireless communications basestation
Applications Automatic meter reading (right) Smart energy management Device-specific billing (plug-in hybrid)
Improving reliability and rate Mitigate impulsive noise Transmit over multiple phases
Standards target ~100 kbps ERDF G3-PLC [Électricité Réseau Dist. France] PoweRline Intelligent Metering Evolution (PRIME) Alliance
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PRIME Standard: Physical Layer Orthogonal Frequency Division Modulation (OFDM)
Divides transmission band into many narrow sub-channels
Transmission Band 42-89 kHzBaseband sampling rate 250kHzSubcarrier spacing 488.28125HzNumber of subcarriers 256FFT size 512 samplesCyclic prefix length 48 samplesNumber of data tones 84 (header) / 96 (payload)Number of pilot tones 13 (header) / 1 (payload)Subchannel constellation Phase-shift keying (2, 4 or 8 levels)Coding convolutional coding (rate ½)Max bit rate (uncoded) 42.9kbps, 85.7kbps, 128.6kbps
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Challenges Powerline Channel Impairments
Multipath and frequency-selective time-variant channel attenuation Background noise, impulsive noise, and narrow-band interference
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Source: Texas Instruments
Challenges (cont.) Performance degradation due to crosstalk
Induced by energy coupling across the phases or wires
Half-duplex operation eliminates ECHO and NEXT Without FEXT cancellation, achievable data rate is significantly degraded
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Presentation Roadmap Framework of PLC Testbed Receiver frame synchronization using a chirp signal Modeling of PLC channel noise
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PLC Testbed Framework of the 1X1 Bidirectional PLC Testbed
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Hardware Software
• National Instruments (NI) embedded computers process streams of data.
• National Instruments ADC/DAC generates/receives analog signals.
• Texas Instruments analog front end enables half-duplex operation.
• Transceiver algorithms implemented as C++ dynamically linked library, running in real-time embedded processors
• Desktop PC running LabVIEW provides GUI for configuring and displaying key system parameters
Receiver Synchronization Using Chirp• PRIME specifies a preamble to begin each burst. Preamble is a linearly frequency modulated chirp over 42-89 kHz
Chirp has constant envelope (in contrast to an OFDM signal) Received signal
Correlated with chirp to find start of burst Used to characterize channel
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SCH (t) Arect(t /T)cos 2 f0t 1/2t 2
f f f0T
,f0 41992 Hzf f 88867 HzT 2048 s
Experimental Results for Synchronization Texas Instrument Development Kit for PLC
Two modems communicate with each other in interleaved manner Gather samples at 250 kS/s
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Rx RxTx Tx
)
One Received Signal Burst
Pre
ambl
e - - - - - - - Payload - - - -
Hea
der 1
Hea
der 2
2.048
- each OFDM symbol is 2.240 ms -
In time domain, a burst has the following structure.
Frame Synchronization by Correlation
[Bumille & rLampe]
Linear scale Log scale
Chirp in Freq. Domain for Channel Est.
FFT length is 512
Ex. Decoding Second Header Symbol
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Looking at positive subcarriers only
BPSK modulated subcarriers (Information in phase)
PLC Channel Noise The powerline channel suffers from non AWGN noise Noise as superposition of five noise types [Zimmermann 2000]
19 Source: Broadband Powerline Communications: Network Design
PLC Channel Noise The powerline channel suffers from non AWGN noise Noise as superposition of five noise types [Zimmermann 2000]
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Colored Background Noise:• PSD decreases with frequency• Superposition of numerous noise sources
with lower intensity• Time varying (order of minutes and hours)
Source: Broadband Powerline Communications: Network Design
PLC Channel Noise The powerline channel suffers from non AWGN noise Noise as superposition of five noise types [Zimmermann 2000]
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Narrowband Noise:• Sinusoidal with modulated amplitudes• Affects several subbands• Caused by medium and shortwave
broadcast channels
Source: Broadband Powerline Communications: Network Design
PLC Channel Noise The powerline channel suffers from non AWGN noise Noise as superposition of five noise types [Zimmermann 2000]
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Periodic Impulsive Noise Asynchronous to Main:• 50-200kHz• Caused by switching power supplies• Approximated by narrowbands
Source: Broadband Powerline Communications: Network Design
PLC Channel Noise The powerline channel suffers from non AWGN noise Noise as superposition of five noise types [Zimmermann 2000]
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Periodic Impulsive Noise Synchronous to Main:• 50-100Hz, Short duration impulses• PSD decreases with frequency • Caused by power convertors
Source: Broadband Powerline Communications: Network Design
PLC Channel Noise The powerline channel suffers from non AWGN noise Noise as superposition of five noise types [Zimmermann 2000]
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Asynchronous Impulsive Noise:• Caused by switching transients• Arbitrary interarrivals with micro-
millisecond durations• 50dB above background noise
Source: Broadband Powerline Communications: Network Design
PLC Channel Noise The powerline channel suffers from non AWGN noise Noise as superposition of five noise types [Zimmermann 2000]
25 Source: Broadband Powerline Communications: Network Design
Can be lumped together as Generalized Background Noise
Generalized Background Noise
26 Source: Broadband Powerline Communications: Network Design
Power spectral density of generalized background noise
Impulsive Noise Asynchronous noise dominates this class of noise
27 Source: Broadband Powerline Communications: Network Design
Need to statistically model two aspects: Impulse amplitude distribution Inter-arrival time between impulses
Asynchronous Impulsive Noise Modeling Amplitude statistics
Class-A Middleton [Umehara]
Weibull Distribution [Umehara]
Empirical Fits [Zimmermann]
Interarrival statistics Exponential distribution [Zimmermann]
Empirical Fits [Zimmermann]
Partitioned Markov chains [Zimmermann]
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Source: Zimmermann
Source: Zimmermann
Preliminary Noise Measurement
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0 10 20 30 40 50 60 70 80 90-125
-120
-115
-110
-105
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Frequency (kHz)
Pow
er/fr
eque
ncy
(dB
/Hz)
Power Spectral Density Estimate
Preliminary Noise Measurement
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0 10 20 30 40 50 60 70 80 90-125
-120
-115
-110
-105
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-95
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Frequency (kHz)
Pow
er/fr
eque
ncy
(dB
/Hz)
Power Spectral Density Estimate
Colored Background Noise
Preliminary Noise Measurement
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0 10 20 30 40 50 60 70 80 90-125
-120
-115
-110
-105
-100
-95
-90
-85
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Frequency (kHz)
Pow
er/fr
eque
ncy
(dB
/Hz)
Power Spectral Density Estimate
Colored Background Noise
Narrowband Noise
Preliminary Noise Measurement
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0 10 20 30 40 50 60 70 80 90-125
-120
-115
-110
-105
-100
-95
-90
-85
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Frequency (kHz)
Pow
er/fr
eque
ncy
(dB
/Hz)
Power Spectral Density Estimate
Colored Background Noise
Narrowband Noise
Periodic and Asynchronous Noise
List of Acronyms/AbbreviationsAcronym/Abbreviation MeaningCyc. Pref. Cyclic PrefixFEC Forward Error CorrectionFEXT Far-end crosstalkLV/MV Low-voltage / medium-voltageMAC Medium Access ControlMIMO Multi-Input Multi-OutputNEXT Near-end crosstalkOFDM Orthogonal Frequency Division
MultiplexingPAPR Peak to average power ratioPHY Physical layerPSD Power Spectral DensitySFSK Spread Frequency Shift Keying
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ReferencesBumiller and Lampe, “Fast Burst Synchronization for PLC Systems,”
Proc. IEEE Int. Sym. Power Line Comm. and its Applications, 2007, pp. 65 - 70
H. Hrasnica, A. Haidine, and R. Lehnert, Broadband Powerline Communications: Network Design, Wiley 2004.
A. G. Olson, A. Chopra, Y. Mortazavi, I. C. Wong, and B. L. Evans, “Real-Time MIMO Discrete Multitone Transceiver Testbed”, Proc. Asilomar Conf. on Signals, Systems, and Computers, Nov. 4-7, 2007, Pacific Grove, CA.
D. Umehara, S. Hirata, S. Denno, and Y. Morihiro, “Modeling of impulse noise for indoor broadband power line communications”, Proc. IEEE Int. Sym. on Information Theory and Its Applications, Oct. 29-Nov. 1, 2006, pp. 195-200.
M. Zimmermann and K. Dostert, "Analysis and modeling of impulsive noise in broad-band powerline communications,” IEEE Trans. on Electromagnetic Compatibility, vol.44, no.1, pp.249-258, Feb 2002.
Freescale solutions for smart metering and smart grid enablement, http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02430Z6A10
Texas Instruments Powerline Communications solutions http://www.ti.com/ww/en/apps/power_line_communications/index.html?DCMP=plc&HQS=Other+OT+plc34