1. RETAIL METERING WORKING GROUP Process for Performing VEE for AMS June 3, 2009

2. 1 AGENDA o Meter Data Flow o Uniform Business Practice – UBP o Inside the MDM –WAVE –iWAVE –Estimation Hierarchy o Data Quality Assurance o Summary 1

3. 2 METER DATA FLOW HEAD END MDMS ODS CIS ERCOTERCOT Daily Register Read Interval Usage Data REPS ERCOT MARKET Market is defined as ERCOT and REPS Bill-Cycle Meter Data COLLECTOR Interval & Register Data Market Settlement Data All Meters Daily Needed by Operating Day +5 30,000,000 Consumption Values DAILY Next Day 150,000 Consumption Values DAILY

4. 3 UBP IS THE BASIS FOR AMS VEE 3 VEE FOR MONTHLY DATA Time check of meter reading device/system (TOU data Only Time check of meter (applies to meters collecting TOU data only) High/low usage check High/low demand check (applies to demand readings only) Time-of-use check (applies to TOU data only) Zero consumption for active meters Usage for inactive meters Number of dials on meter Dial decimal quantity Meter identification VEE FOR INTERVAL DATA Time check of meter reading device/system Meter identification check Time check of meter Pulse Overflow check Test Mode check Sum check Spike check Reactive channel check High/Low Usage check http://www.naesb.org/pdf/ubp120500.pdf

5. 4 UBP IS THE BASIS FOR AMS VEE 4 AMS VEE RULES Missing Intervals Pulse Overflow Test Mode Reverse Rotation Meter Reset Time Change Power On/Off Maximum Demand Spike Check Sum Check Consecutive Zeros AMS ESTIMATION RULES Maximum Interpolation Span Maximum Estimation Span Like Day Estimation Criteria Register Allocation Class Profile Estimation EXPERIENCE IN THE AMS WORLD MAY INDENTIFY AREAS FOR CHANGE IN THE UNIFORM BUSINESS PRACTICES PRIOR VALIDATION RULES THAT WERE DESIGNED TO IDENTIFY HUMAN ERROR MAY NO LONGER BE APPLICABLE PRIOR INTERVAL DATA ESTIMATION PROCESSES WERE MANUAL http://www.naesb.org/pdf/ubp120500.pdf

6. 55 NUMRULEDEFINITION 1Time check of meter reading device/system Ensure collection device time clocks are synchronized to the national time standard 2Time Check of the meterEnsure meter time clocks are synchronized 3 Time Tolerance Check [meter and data] Minimize clock drift between the meter and the collection device/system 4 Power-OnIdentify if electricity is currently available at the meter location 5 Pulse OverflowIdentify interval value exceeds the registration range 6 Test ModeConfirms data collected during test modes are flagged 7 Sum CheckEnsure the sum of the intervals matches the Register 8 Usage for Inactive metersIdentify a location that should not be consuming electricity 9 Missing IntervalsSelects how the system will handle missing interval data VALIDATION RULES EXAMPLE

7. 6 ERCOTERCOT ESTIMATION METHOD EXAMPLES System Allows for GROUP Specific Rules Wave performs ADU calculation: Customer Previous Month X (Group Current Month / Group Previous Month ) iWAVE Calculation: Residential Scales ERCOT Forecast Profiles C&I Scales the past Same days average shape Same Day Average Tues is Tues is Tues Like Day Average Weekday, Weekend, Holiday Load Profile Shape ESTIMATION IS REQUIRED CALCULATE USING FIRST RULE CHOICE CALCULATE USING NEXT RULE CHOICE Is the Required Historical Actual Data Available to Use Rule?

8. 7 ERCOTERCOT VISUAL ESTIMATION EXPLANATION iWAVE CREATES A LOAD CURVE VIA THE ESTIMATION HEIARCHY SELECTED iWAVE CREATES A LOAD CURVE VIA THE ESTIMATION HEIARCHY SELECTED WAVE SCALES THE LOAD CURVE UP OR DOWN AS NEEDED WAVE SCALES THE LOAD CURVE UP OR DOWN AS NEEDED

9. 8 ERCOTERCOT INITIAL SETTING SELECTED Scaled ADU calculated using data for similar customers and for the same customer, location, day type, climate zone from the prior billing month. 1 Scaled average daily usage (ADU) which is calculated using data for similar customers and for the same customer and location from the prior billing month. 2 Scaled average daily usage (ADU) which is calculated using data for similar customers and for the same customer and location from the prior years same billing month. 3 Calculated average daily usage (ADU) for the same rate code and climate zone as the scaling factor to be applied to the average daily usage (ADU) for the previous billing month for the same customer and location 4 Calculated average daily usage (ADU) for the same rate and climate zone as the scaling factor to be applied to the average daily usage (ADU) for the prior year s same billing month for the same customer and location 5 WAVE

10. 9 ERCOTERCOT INITIAL SETTING SELECTED iWAVE RulePriority C&IPriority Residential Same days estimation for the same customer and location 13 Like days estimation for the same customer and location 22 Reference Load Profile Data * 31 Static Load Profile Data N/A

11. 10 CIS Market MDMSHead-EndRF Meter Validation Estimation & Editing Transmit to ERCOT and REPs Routine Reads Read the Meter Interval and Register Reads Validate file quality ERCOT Business Goals Processes Collect VEE Manage the Data Present the Data Details + Batch & Push Batch & Push Retrieval Gap Check Retrieval Gap Check Every 4 hrs 6x day Additional stored data sent: Distributed Generation, TOU, Demand Register and Power Factor Collect the data REPs Flag exceptions Record daily register read Once Daily at Midnight Every 4 hrs Billing file created Wires Billing CIS Audit rules EDI Gateway Bill Cycle Interval ODS 30 Million Reads Daily 150 k Reads Daily AMS System

12. 11