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 I NTRODUCTION  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 P ROGRAM B ACKGROUND  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 E XISTING I NFRASTRUCTURE  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 D EMOGRAPHICS  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 O PTIMUM L OAD S HED W INDOW

7 W HY 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 P ROGRAM G OALS  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 E NHANCEMENTS  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 N EW I NFRASTRUCTURE  Using the portable transmitter allows DTE to now target interruptions to localized substations and/or circuits versus a whole geographic area

11 E QUIPMENT (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 H ARDWARE Transmitter RTC Laptop

13 Antenna

LSLR P ILOT T EST  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 S LOAN S UBSTATION (Load Shed Curve)

16 E CONOMIC A NALYSIS 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

LSLR P ROGRAM  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

LSLR P ROGRAM  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 C ONCLUSION  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

20 S IGNIFICANT T AKE A WAYS  Strategic Load Research  Leveraging data and knowledge for Corporate success  LR recognized a problem and developed a value adding initiative to resolve