5 RPG MeetingOctober 16, 2009 Northwest Houston Reliability Project CenterPoint Energy proposed the Northwest Houston Reliability Project to resolve reliability problems in the area due to expected load growth Original proposed in-service date was 2012 New load forecasts show lower load predictions through 2014 Model/Case 2012 Updated December Updated June Updated June Updated June 2009 Area Load (MW)
6 RPG MeetingOctober 16, 2009 Northwest Houston Reliability Project ERCOT Independent Review (using June 2009 SSWG base cases) showed no reliability problems in the area in 2012 and analysis revealed the need for the following upgrades to relieve post-contingency overloads (Option 1): –Install a new 345/138 kV 800 MVA autotransformer at T.H. Wharton in parallel with the existing 800 MVA autotransformer # 1 –Convert Klein substation to a breaker substation and build a new 138 kV circuit from T.H. Wharton to Klein –Reconductor circuit 76 Cy-Fair to Kluge
8 RPG MeetingOctober 16, 2009 Northwest Houston Reliability Project As an alternative ERCOT tested a modified version of CenterPoint Energy’s preferred solution (Option 2): –Expand 345 kV Zenith to 345/138 kV substation and install a new 345/138 kV 800/1000 MVA autotransformer –Build a new 138 kV double circuit from the new 138 kV Zenith substation to Gertie Row and connect to existing 138 kV double circuits to Gertie –Reconfigure the existing 138 kV circuit 76 from Kluge to Addicks and circuit 21 from Kluge to Camron to create three new 138 kV circuits: circuit 1 from Zenith to Addicks, circuit 2 from Zenith to Kluge and circuit 21 from Kluge to Camron –Reconductor circuit 2 Cy-Fair to Kluge
10 RPG MeetingOctober 16, 2009 Northwest Houston Reliability Project Both options solved reliability problems in 2014 Cost –Option 1 = $25.3 million –Option 2 = $25.5 million No congestion in area: projects did not create or relieve any congestion Option 2 provides new 345 kV to 138 kV injection point Option 2 alleviates the loss of 400 MW of load due to single tower (double circuit) contingency CenterPoint Energy’s analysis revealed that with future load growth Option 2 will require fewer upgrades in the long run ERCOT recommended Option 2 as the preferred solution –Recommended 2014 but could be 2013 if load growth increases sooner
11 RPG MeetingOctober 16, Houston Import Study Houston Import Study
12 RPG MeetingOctober 16, Houston Import Study Why are we studying this? –ERCOT Independent Review of Sharyland’s ERCOT Southeast Loop RPG Project (Tier 1) –ERCOT 2009 Five-Year Transmission Plan Economic Analysis –Ongoing congestion in real-time –ERCOT Independent Review of Centerpoint’s North to Houston Constraint Mitigation RPG Project (Tier 1)
13 RPG MeetingOctober 16, Houston Import Study Assumptions Study Assumptions –Base case = YTP 2014 Economic Start Case Includes all YTP reliability projects identified for 2014 Includes all CREZ transmission facilities Does not include additional CREZ generation –Analysis will focus on economic benefit of additional import capacity into Houston area per ERCOT RPG Charter and Procedures Section 3.3 UPLAN Assumed load can be served reliably without additional import capability, but additional import project may allow reliability criteria to be met at a lower overall cost –Interface limits used as proxy for voltage stability limits
14 RPG MeetingOctober 16, Houston Import Study Approach Base Case BC + CREZ Generation BC + STP 3 & 4 BC + STP 3 & 4 BC + New Gas Gen North of Houston BC + New Gas Gen In Houston BC + Load Variation BC + Comanche Peak 3 & 4 Bulk of analysis will focus on the base case. Options may be eliminated at this stage. Alternate scenarios will be used to quantify relative merit of options that pass first stage. Final recommendation will be selected. Sensitivity scenarios will be run for recommended option and results added to report.
17 RPG MeetingOctober 16, Houston Import Study Initial findings –Initial results indicated little savings until other 5YTP upgrades implemented –Upgrading/ adding import paths into Houston from the south did not produce significant savings Options 19, 24, and J3 are no longer being considered –Adding import paths into Houston from the north and/ or west revealed significant production cost savings but not enough to justify the cost of the project using the societal benefit test However, some did produce enough energy revenue (consumer benefit) savings to justify the cost of project –Per ERCOT RPG Charter and Procedures Section 3.3 –Relaxing N-H and S-H voltage constraints generally increased the production cost and energy revenue savings Comments?
18 RPG MeetingOctober 16, 2009 Savings with voltage constraints (preliminary) Options Total Cost ($ million) Savings Needed ($ million) PC Savings ($ million) Energy Revenue Savings ($ million) A A J J1A J E DC n/a
19 RPG MeetingOctober 16, 2009 Savings without voltage constraints (preliminary) Options Total Cost ($ million) Savings Needed ($ million) PC Savings ($ million) Energy Revenue Savings ($ million) A A J J1A J E DC n/a
20 RPG MeetingOctober 16, Houston Import Study Issues for comment –Is it appropriate to apply voltage stability constraints to 2014 case? –How should Category D contingency of Zenith substation outage be considered? –Which options can be dropped from further analysis based on the Base Case production cost savings or energy revenue savings? Next Steps –Finalize base case analysis –Test options that pass first step in alternate scenarios