1. Power Line Communications for Enabling Smart Grid Applications
Prof. Brian L. Evans, Embedded Signal Processing Laboratory, The University of Texas at Austin
Students: Jing Lin, Yousof Mortazavi, Marcel Nassar, Karl Nieman
Objective: Develop real-time bi-directional power line communications (PLC) transceiver testbed to aid in system design and algorithm analysis.
“LAST MILE” OF SMART GRID
CHANNEL IMPAIRMENTS
Channel model:
Mitigation methods:
non-AWGN receiver (cyclostationary noise model accepted into IEEE )
estimate noise statistics w/ null tones
reduced complexity noise shaping
equalization, dynamic bit allocation
Communications over low and medium voltage
infrastructure (at the neighborhood level)
smart energy management
(dynamic load balancing)
automated meter reading
device-specific billing
home area networks for
rural customers
filter + +
fading
Gaussian
non-Gaussian
Local power area network
STANDARDS AND BEYOND
Interference sources in PLC systems
Estimates of noise power spectra for indoor AC outlet (top) and St. Louis outdoor PLC field trial (bottom) measurements
Competing PLC standards
G3 and PRIME are international standards for low and medium voltage power lines.
Both standards based upon:
multicarrier via OFDM
mid-frequency
(kHz) operation
narrowband
(lower data rates)
Parameter
PRIME G3
Transmission band
42-89 kHz
kHz
Sampling frequency
250 kHz
400 kHz
FFT length
512
256
Cyclic prefix length 48 30
Subcarrier spacing
488 Hz
kHz
OFDM symbol duration
2240 μs
640 μs
Max data rate
128.6 kbps
33.4 kbps
REAL-TIME PLC TESTBED
Objective: Deploy ESPL-developed techniques to mitigate non-Gaussian noise in real-time testbed.
Hardware
Software
National Instruments (NI) controllers stream data
NI cards generate/receive analog signals
Texas Instruments 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.
Our Approach: Multichannel (MIMO) OFDM over Power Line
The use of MIMO techniques across multiple phase systems (i.e. phase, neutral and ground) could potentially double or even triple currently-achievable data rates. However, cross-talk induced by coupling between the wires could reduce ultimate throughput.
PLC testbed with suite of
user-selectable algorithms
AFE
ECHO
TX A
TX B
RX C
RX D
RX A
RX B
TX C
TX D
NEXT
FEXT
mode 1
mode 0
Powerline
Our prior work on a real-time wired 2x2 MIMO OFDM system achieved 2x data rate using:
Far-end crosstalk cancellation
Near-end crosstalk cancellation
Other adaptive algorithms
Bit rates over a 1000 ft CAT-5e cable using 2x2 MIMO OFDM testbed
DELIVERABLES
Ongoing work: single-transmitter single-receiver (1x1) powerline communication testbed
Looking ahead: multiple-transmitter multiple-receiver (MIMO) powerline communication testbed
SRC support via Freescale, IBM, and Texas Instruments, GRC Task