Powerline Communications for Enabling Smart Grid Applications

1. Prof. Brian L. EvansWireless Networking and Communications Group The University of Texas at Austin Powerline Communicationsfor Enabling Smart Grid Applications SRC GRC Annual Review March 8, 2011

2. Task ID 1836.063 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 StudentsCurrent Status Ms. 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

3. Task Deliverables • 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)

4. 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

5. Background: 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 5

6. Background: Voltage Levels in Grid High-Voltage Medium-Voltage Low-Voltage Concentrator Source: ERDF “Last mile” PLC communications on low/medium voltage line

7. Motivation for “Last Mile” PLC 7 • 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 Source: Powerline Intelligent Metering Evolution (PRIME) Alliance Draft v1.3E 7

8. PRIME Standard: Physical Layer • Orthogonal Frequency Division Modulation (OFDM) • Divides transmission band into many narrow sub-channels

9. Challenges • Powerline Channel Impairments • Multipath and frequency-selective time-variant channel attenuation • Background noise, impulsive noise, and narrow-band interference Source: Texas Instruments

10. 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

11. Presentation Roadmap • Framework of PLC Testbed • Receiver frame synchronization using a chirp signal • Modeling of PLC channel noise

12. PLC Testbed • Framework of the 1X1 Bidirectional PLC Testbed

13. 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

14. 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 Rx Tx Rx Tx )

15. One Received Signal Burst • In time domain, a burst has the following structure. Preamble Header 2 Header 1  - - - - - - - Payload - - - -    2.048  - each OFDM symbol is 2.240 ms - 

16. Frame Synchronization by Correlation Linear scale Log scale [Bumille & rLampe]

17. Chirp in Freq. Domain for Channel Est. FFT length is 512

18. Ex. Decoding Second Header Symbol Looking at positive subcarriers only BPSK modulated subcarriers (Information in phase)

19. PLC Channel Noise • The powerline channel suffers from non AWGN noise • Noise as superposition of five noise types [Zimmermann 2000] Source: Broadband Powerline Communications: Network Design

20. PLC Channel Noise • The powerline channel suffers from non AWGN noise • Noise as superposition of five noise types [Zimmermann 2000] • 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

21. PLC Channel Noise • The powerline channel suffers from non AWGN noise • Noise as superposition of five noise types [Zimmermann 2000] • Narrowband Noise: • Sinusoidal with modulated amplitudes • Affects several subbands • Caused by medium and shortwave broadcast channels Source: Broadband Powerline Communications: Network Design

22. PLC Channel Noise • The powerline channel suffers from non AWGN noise • Noise as superposition of five noise types [Zimmermann 2000] • Periodic Impulsive Noise Asynchronous to Main: • 50-200kHz • Caused by switching power supplies • Approximated by narrowbands Source: Broadband Powerline Communications: Network Design

23. PLC Channel Noise • The powerline channel suffers from non AWGN noise • Noise as superposition of five noise types [Zimmermann 2000] • 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

24. PLC Channel Noise • The powerline channel suffers from non AWGN noise • Noise as superposition of five noise types [Zimmermann 2000] • Asynchronous Impulsive Noise: • Caused by switching transients • Arbitrary interarrivals with micro-millisecond durations • 50dB above background noise Source: Broadband Powerline Communications: Network Design

25. PLC Channel Noise • The powerline channel suffers from non AWGN noise • Noise as superposition of five noise types [Zimmermann 2000] Can be lumped together as Generalized Background Noise Source: Broadband Powerline Communications: Network Design

26. Generalized Background Noise Power spectral density of generalized background noise Source: Broadband Powerline Communications: Network Design

27. Impulsive Noise • Asynchronous noise dominates this class of noise • Need to statistically model two aspects: • Impulse amplitude distribution • Inter-arrival time between impulses Source: Broadband Powerline Communications: Network Design

28. 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] Source: Zimmermann Source: Zimmermann

29. Preliminary Noise Measurement

30. Preliminary Noise Measurement Colored Background Noise

31. Preliminary Noise Measurement Narrowband Noise Colored Background Noise

32. Preliminary Noise Measurement Periodic and Asynchronous Noise Narrowband Noise Colored Background Noise

33. List of Acronyms/Abbreviations

34. References Bumiller 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+plc