1. Wireless Data Communication in Substations Mladen Kezunovic (P.I.) Alireza Shapoury PS ERC PSerc Meeting Texas A&M University College Station November, 2002

2. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station2 OUTLINE  Introduction  Overview of the Problem  Objectives  Projects Tasks (Technical Approach)  Results  Conclusions

3. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station3 INTRODUCTION Use real-time and off-line data for better maintenance management Utilize new technologies of wireless communications and mobile agents As an example, improve efficiency of circuit breaker maintenance assessment Demonstrate the benefits of new communication and software technologies using utility maintenance management scenarios

4. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station4 INTRODUCTION Pros of Wireless Network Cheaper than (often-expensive) cabling version More relaxed constraint on isolation level and clearances Portability/mobility Susceptibility to unstable grounds Convenience and ease of installation Easier implementation of higher Insulation Protection (IP) of instruments Extend range of data acquisition and I/O (large scale operation)

5. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station5 THE FIRST GLANCE Known Use License-exempt ISM (Industrial,scientific and Medical) Band (Cost-free to use the spectrum) FCC Allows Higher RF Power If Spread Spectrum (3-4 times improvement in transmit range) Upper Network Layers Already Developed (No need to reinvent the wheel) Not Sure Suitability of Existing Solutions For This Particular Application Sure Solutions Not Tested/Evaluated for This Application OVERVIEW OF THE PROBLEM

6. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station6 Already Well-developed Wireless Network Standards IEEE 802.11 IEEE 802.16 More on Appendix A What is the difference? Their Physical (PHY) and/or Medium Access Control (MAC) Are Not Optimized/Assessed to Operate in The: FIXED LOCATION IMMEDIATE VICINITY OF HIGH TRANSIENT SOURCE Adopt Other Standards for Upper Layers OVERVIEW OF THE PROBLEM

7. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station7 OBJECTIVES Identifying the Probable Impacts of the Environment (What Should We Look for?) Design Measurement Setup Plans Conduct Series of Measurements to Probe Our a Priori Knowledge Process the Data to Acquire Relevant and Updated Understanding Defining the Most Appropriate Wireless Strategy for Substation Environment

8. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station8 PROJECT TASKS I. I.Theoretical Analysis and Technical Observations II. II.Field Measurement Setup Plans III. III.Data Analysis and Post-Processing IV. IV.Identifying Reliable System Characteristics V. V.Documentation

9. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station9 Impulsive noises and EMI Impact On Wireless Channel Noise Sources In Substations Review of The Noise Impact On the Core Spread Spectrum Schemes Crude Comparison Of DSSS And FHSS Worst-case Analysis Worst-case happens under different noise profiles for DSSS and FHSS I. I.THEORETICAL ANALYSIS AND TECHNICAL OBSERVATIONS

10. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station10 DSSS indicates approximately 5dB superior to that of FHSS under worst-case noise profile of their own Assessment of the likelihood of the Worst-case situations necessitates measurement I. I.THEORETICAL ANALYSIS AND TECHNICAL OBSERVATIONS

11. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station11 II. II.FIELD MEASUREMENT SETUP PLANS  Measuring Parameters (Statistics) Average Noise Power Average Signal Power Average Packet Error Temperature  Measurement Devices, Configurations and Operation Modes  Investigating Practical Issues (E.g. Antenna Type and Location, Proper Output Power)

12. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station12 I.Propagation Profile Measurement II.IEEE802.11 Based Site-Specific Measurement III.900MHz Long-Term Site Survey IV.2.4GHz Long-Term Site Survey II. II.FIELD MEASUREMENT SETUP PLANS

13. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station13 IEEE Has a Recommendation Practice for Site Survey The Measured Data Has a Strong Non-random Component With Long-time Memory and a Stationary Internal Structure, Which Calls for Time Series Analysis. Our Statistical Analysis Suggests That The Mostly-Used Classical Distributional Analysis Is Not Appropriate Unless Incorporated With Time Series Analysis. III. III.DATA ANALYSIS AND POST-PROCESSING

14. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station14  Achievable Baud Rate For Wireless Channel  Maximum BER For Data Devices  Necessary Response Time For The Wireless Device  Antenna  Power Supply And Isolation  Adequate Data Security IV. IV.IDENTIFYING RELIABLE SYSTEM CHARACTERISTICS

15. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station15  Progress Reports  Final Report  Preparing Some Publications V. V.DOCUMENTATION

16. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station16  Accomplishments  Identification of Noise Sources in Substation  Worst-case Analysis for Two Core SS Modulation Formats  Extraction of the Necessary Parameters (to Be Measured)  Measurement Setup (Modifications, Verifications and Programming )  Conducting Several Long-term Measurement Runs CONCLUSION

17. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station17  Accomplishments (Cont.)  Presenting a Methodology for Post Processing of Data  Investigating the Impacts of Substation Electrical Parameters (E.G. Voltage Levels, Power, Etc) on Wireless Link Quality  General Requirements and Recommendations for the Wireless System Candidates CONCLUSION

18. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station18  Results in a Nutshell  Noise Analysis in This application requires time series analysis  Impacts of Slow-Varying processes in Substation  Load pattern and even Voltage levels have no or little impact over the link quality on Average  Ambient and Transformer Temperatures have no or little impact on the link quality on Average  Transformer Temperature has no or little impact on the link quality on Average CONCLUSION

19. PS ERC PSerc MeetingNovember, 2002Texas A&M University at College Station19  Results in a Nutshell (Cont.)  Impacts of Fast-varying Processes in Substation  Sharp Peaks and Troughs May Cause Link Disruption  The Existence of the Impulsive Signal Level Variation Should Be Considered by Wireless Designer (Increasing the TR Power Settings)  ~14 dB Variation (900 MHz)  ~20 dB Variation (2.4 GHz)  Signal Level variation seems to be strongly depending on the location of the substation i.e. Rural, Industrial,etc (almost 6 dB difference in link quality) CONCLUSION