© ABB Group August 23,2010 | Slide 1 MBPC Study – 1 st Load Pocket Preliminary Results for Discussion only Entergy Regional State Committee (ERSC) Southwest Power Pool (SPP) February 16, 2011 ABB Inc., Electric System Consulting Dept. ERSC

© ABB Group August 23,2010 | Slide 2 Agenda  Study Overview  Study Status  Task List and Study Approach  Case List  Reference Case  Production Costing  Power Flow  Very Preliminary Results for Western Load Pocket  Production Costing  Power Flow Analysis  Next Steps

ERSC © ABB Group August 23,2010 | Slide 3 Study Status  Study assumption document submitted for review  Completed development of production costing and power flow models for 2013 Reference Case (RMR nomograms enforced)  Analysis started for Western Load Pocket

ERSC © ABB Group August 23,2010 | Slide 4 Task List Task 1 – Develop Data base and System Models Task 2 – Transmission Analyses with RMR Unit Task 3 – Transmission Analyses w/o RMR Unit & no Transmission Change Task 4 – Transmission Analyses w/o RMR Unit & Transmission Change Task 5 – Production Cost Simulation with RMR Unit Task 6 – Production Cost Simulation w/o RMR Unit & no related Transfer Limit Constraint Task 7 – Production Cost Simulation w/o RMR Unit & with Transmission Changes Task 8 – Economic Comparison of Benefits and Costs Task 9 – Collate results by Units, Plants and Groups. Task 10 – Congestion Analysis Task 11 – Fuel Price Elasticity Task 12 – Sensitivity Analysis Task 13 – Perform ATC Calculations Task 14 – Study Report Preparation, Discussion and Presentation Task 15 – Additional Transmission Upgrades required for Flexible Capacity (Optional)

ERSC © ABB Group August 23,2010 | Slide 5 Study Approach - Overview

ERSC © ABB Group August 23,2010 | Slide 6 Case List

ERSC © ABB Group August 23,2010 | Slide 7 Reference Case  Reference case provides a base for determining the impact of removing the RMR designations for the study units  RMR nomograms are enforced in the reference case  Modeling assumptions described in Study Assumptions Document

ERSC © ABB Group August 23,2010 | Slide 8 Reference Case (Production Costing)  Benchmarked with Entergy units, using following statistics for 2007, 2008, 2009: Annual energy production Annual service hours  RMR guidelines modeling was verified  Operating reserve modeling was verified  Entergy generation units data were checked

ERSC © ABB Group August 23,2010 | Slide 9 Reference Case (Power Flow)  Reference case represents system conditions at the Entergy system peak hour (Aug. 26, 3 pm)  Started from 2013 power flow case prepared by SPP-ICT  Synchronized Loads in the Power Flow and Production Costing at the peak hour  Synchronized dispatch of generating units within Entergy footprint based on Production Costing dispatch (SCED) at the peak hour  Also ensured interchange between Entergy footprint and Tier 1 matches Production Costing interchange  Entergy footprint totals at the peak hour:  Load + losses: 33,810 MW  Generation: 32,068 MW  Import from Tier 1: 1,742 MW

ERSC © ABB Group August 23,2010 | Slide 10 Reference Case (Power Flow)

ERSC © ABB Group August 23,2010 | Slide 11 Reference Case Results (Power Flow)  Ran power flow analysis on Reference Case to check steady-state performance in Entergy footprint for following conditions:  System intact  N-1 contingencies  G-1,N-1 contingencies (WOTAB and Amite South)  Results submitted to SPP  SPP reviewed results and provided Construction Plan projects and comments on results

ERSC © ABB Group August 23,2010 | Slide 12 Western Load Pocket Analysis  Following cases were simulated Case Name Definition West_0Same as reference case West_1Same as West_0 with no nomogram West_2Same as West_1 with no Western area transmission limits and no limits on 8 tie-lines between Western & WOTAB in production costing analysis West_3Same as West_0 with plant turned off West_4Same as West_3 with no Western area transmission limits and no limits on 8 tie-lines between Western & WOTAB in production costing analysis

ERSC © ABB Group August 23,2010 | Slide 13 Western Analysis (Contd.) Preliminary results For case West_1, it is found that:  Lewis Creek units are still being dispatched on the security constrained economic dispatch basis and also due to transmission constraints that limit the import of power into the WOTAB/Western load pocket.  Power flow analysis: When RMR designation was not used for Western units (Case West_1), generation dispatch is identical to that in the Reference Case (West_0 with RMR rule enforced) at the peak load hour. Hence, there was no need to repeat power flow for the West_1 Case.

ERSC © ABB Group August 23,2010 | Slide 14 Western Analysis (Contd.) Preliminary results  In Case West_2, reduction (appr. 40%) in the Lewis Creek plant annual energy (MWh) production was observed.  Power flow analysis showed degradation in steady-state performance (more overloads) compared to West_1 case, because the plant was dispatched at about 20% lower MW level (than in West_1 Case) during Entergy’s peak load hour.

ERSC © ABB Group August 23,2010 | Slide 15 Western Analysis (Contd.) Preliminary results  For West_3 Case, with Lewis Creek plant turned off, the annual production cost, in the Entergy footprint, increased.  Power flow analysis showed further degradation in steady-state performance (overloads) compared to West_2 case, including Voltage Collapse for certain double contingencies and several G1N1 contingencies. This is mainly due to erosion of reactive capability in Western Load pocket.  The results for West_4 Case were similar to West_3 Case.

ERSC © ABB Group August 23,2010 | Slide 16 Next Steps  Relieve all constraining flowgates  Increase WOTAB import limit  Power flow analysis will be run to check for transmission constraints associated with import of cheaper power into Western  Addition of transmission projects to increase load pocket import capability  Analysis (production costing and power flow): a) Is more economical generation available than assumed in the Production Costing model? b) If so, does that case require associated transmission fixes? - PV curves, OPF etc.

ERSC © ABB Group August 23,2010 | Slide 17 Q & A Thank you!