The Localized Substation Load Relief (LSLR) Program at Detroit Edison

1. The Localized Substation Load Relief (LSLR) Program at Detroit Edison Presentation by: Traci MacDonald AEIC National Conference September 10-13, 2006 Silver Legacy Resort Casino - Reno, NV

2. INTRODUCTION • Background on DTE’s Interruptible Air Conditioning (IAC) Program • Enhancements to the existing IAC program for development of the Localized Substation Load Relief (LSLR) program • LSLR Equipment • Results of the LSLR Pilot Test in 2004 • Summer of 2005 and 2006 results

3. IAC PROGRAM BACKGROUND • IAC program has historically been used for generation load relief • IAC tariff states that DTE can cycle service to IAC customers for reasons including, but are not limited to, maintaining system integrity, economics or when demand exceeds generation • Cycled interruptions of 15 minutes on and 15 minutes off allow for 30 minutes of cooling by A/C unit every hour • IAC customers can only be interrupted for a maximum of 8 hours/day • Eleven control towers in the DTE service territory are capable of transmitting interruption signals to all IAC customers

4. EXISTING INFRASTRUCTURE • Having 11 towers allows DTE the flexibility to interrupt all 285,000 IAC customers or just target a specific geographic location to maximize interruption value

5. IAC DEMOGRAPHICS • DTE currently has around 285,000 IAC customers • Expected load shed is approximately 1 kW for each IAC customer • About 250 MW’s of interruptible IAC load on the distribution system • There are close to one million households still remaining in the service territory as potential IAC customers • Sample and Control sites already out in the field which allow LR to analyze usage and study behavior patterns for this class

6. OPTIMUM LOAD SHED WINDOW

7. WHY LSLR? • DTE occasionally exceeds distribution capacity limits on localized circuits during the summer peak season and prior to LSLR, needed to rotate whole circuits to maintain system reliability • Started to focus on using IAC customer sites to provide relief for overloaded substations • The existing IAC program only needed minor tweaking to accommodate the LSLR goals • IAC program historically used to provide load relief at the generation level; now it can also be used to provide relief to localized overloaded distribution circuits

8. LSLR PROGRAM GOALS • Minimize the need for whole circuit interruptions • Minimize inconvenience to customers by interrupting only IAC loads as opposed to whole house interruptions • Minimize revenue loss to DTE • Provide System Operators with an additional load management tool that can be used to shed load at substations nearing emergency levels

9. ENHANCEMENTS • Replaced the use of a single control tower with a low power portable transmitter • Equipped an existing DTE vehicle with a transmitter, an antenna and a laptop with the Load Management System (LMS) software • Ability to drive directly to the substation(s) in need of load relief • Transmitter sends a 2 mile radius interruption signal to the area surrounding the substation and minimizes interruptions to IAC customers outside the substation service territory

10. NEW INFRASTRUCTURE • Using the portable transmitter allows DTE to now target interruptions to localized substations and/or circuits versus a whole geographic area

11. EQUIPMENT(Cost per Vehicle) • Remote Transmitter Controller (RTC): $4,000 • Load Management (LMS) Software: $1,500 • Antenna: $250 • Laptop Computer: Stock Item • Transmitter: Stock Item • Company Vehicle: Stock Item

12. LSLR HARDWARE Laptop Transmitter RTC

13. Antenna

14. 2004 LSLR PILOT TEST • Purpose was to determine if a portable transmitter could be used to send an interruption signal to 2,121 IAC customers at Sloan substation • Predicted average load shed was 2.0 MVA • Average load shed was 1.8 MVA • Pilot Test was a success!

15. SLOAN SUBSTATION(Load Shed Curve)

16. ECONOMIC ANALYSIS Economic Analysis (based on 2,121 customers): • Lost revenue due to whole house interruption/hour: $340 • Lost revenue due to IAC interruption/hour: $150 • DTE net savings/hour: $190 ($340 - $150) • DTE net savings per 8 hours: $1,520 Payback: • Cost of Program per Mobile Vehicle: $5,800 • LSLR Payback Period: approximately 4 days of use

17. 2005 LSLR PROGRAM • System Operators determined substations in need of relief and LR dispatched Telecommunications to the field • LR accompanied Telecommunications to the field and assisted with equipment set up and provided on-site training for the program • The LSLR team responded to all 47 LSLR requests by System Operators • Used LSLR on 23 occasions at 26 different substations • The LSLR team was successful in all but 1 request to reduce load at substation sites; that failure was due to an equipment malfunction

18. 2006 LSLR PROGRAM • System Operators resumed the role of dispatching the LSLR teams to the field • Telecommunications supported the field work for the LSLR program and LR provided oversight for the project • LSLR team responded to all 10 LSLR requests by System Operators and shed load on 8 occasions • Used LSLR on 8 occasions at 7 different substations

19. LSLR reduces the number and duration of whole circuit interruptions and in some cases, eliminates the need for circuit rotation altogether Increases customer satisfaction as customers would prefer cycled A/C interruptions rather than whole house interruptions Relatively minor program costs with no additional labor expense LSLR CONCLUSION

20. SIGNIFICANT TAKE AWAYS • Strategic Load Research • Leveraging data and knowledge for Corporate success • LR recognized a problem and developed a value adding initiative to resolve