1 Integration of Variable Generation into the Grid: Need for TVLs (Transfer Variability Limits) Gordon Dobson-Mack (Chair) Dynamic Transfer Capability Task Force Wind Integration Forum – Steering Committee November BCCPG

2 Discuss the need for TVLs and what can be done to increase them Purpose of Presentation

3 1.Variability & its impacts: –Increased variability is a reality for operations; –Dynamic Transfers contribute to variability; –Transfer Variability impacts the grid; –Need Transfers Variability Limits for some systems. 2.DTC Task Force –Mandate & Membership; –Deliverables; 3.What Next? –Questions & Options; Outline

4 BPA’s Installed Wind Source: BPA:

6 NWPP Wind Generation Levels 2010 Coincident Peak Load = 60,200 MW Dec 2010 Installed Wind Gen = 7,800 MW Dec 2012 Installed+Committed Wind Gen = 13,200 MW 2010 Spring Min Load (HE04) = 32,745 MW Source: NWPP & DTC TF: search “DTCTFPhaseFullReport pdf”

7 Source: see slide #3http://

Generation Problem: –Need to maintain Generation Balance; –Want access to least cost & most flexible Ancillary Services Transmission Problem…As well: –Transmission system designed historically for routine predictable changes; –Must be ready to withstand the next worst contingency; –Voltage control and RAS arming are local measures that must be factored into the solution. Generation or Transmission Problem?

9 R L C C CC C Load Transmission Line Transmission Line Physics

10 Maximum TTC, Transmission Tuned Light Load or line open - High Voltage unless reactive switched off Low Voltage: Without added Reactive – could Be a voltage collapse Reactive “Tuning” And Remedial Action Schemes (RAS)

Power - Voltage Curves and Reliability N-1 Limits N-1 Outage Acceptable Voltage Range Voltage Level N-1 Outage Reliability Limits Operating MW Range no Caps in MW Power Level Operating MW Range Caps in Capacitor Switched on Normal N-0

Added Switching Remedial Action Schemes (RAS) RAS arm RAS un-arm Capacitor In Capacitor Out Minutes MW Flow 1850 MW 2050 MW Path flow with VG Traditional tie line flow

13

14 Present Dynamic Schedule Requirements Montana – NW 50 MW BPA Loads 20 MW Glacier Wind 1318 MW Colstrip Participants 91 MW NWE Idaho – NW 200 MW PAC 60 MW Boardman DTC Studies-BPA Report (Feb 2010)

15 DTC Task Force – Part of Wind Integration Study Team (WIST) DTC Task Force Convened October 2010 Technical Staff primarily from NW & CA entities ~55 Meetings to date. Purpose: 1.Develop a technical consensus on how to facilitate increased Dynamic Transfers without compromising system reliability 2.BAs & TPs to establish DTC Limits on paths 3.Determine if & how to expand DTC

16 DTC TF (Phase 3 )Membership Avista: Rich Hydzik BPA: Brian Tuck, Ramu Ramanathan BCH: Steven Pai, Sanjeet Sanghera, CAISO: Jim Price Gaelectric: Dan Wheeler IPCO: Orlando Ciniglio MSR: Dave Arthur, Ann Fisher NWE: Rikin Shah, Ray Brush PAC: Sanman Rokade PGE:Philip Augustin, Don Johnson PSE: Alex Berres, Joe Seabrook TANC: Abbas Abed, Shawn Matchim SMUD: Richard Buckingham WAPA (Folsum): Kirk Sornborger Powerex: Gordon Dobson-Mack DTC TF Chair Tel: Columbia Grid: Marv Landauer Northern Tier: Rich Bayless NWPP: Don Badley 3

17 DTC TF Work Process Phase 1 (03/11) Phase 2 (07/11) Phase 3 (11/11)

18 Three Conditions Restricting Transfer Variability Limits

19 Does not calculate TVLs for particular Paths; –Recommends a methodology; –Leaves limit calculations to Transmission Providers Does not recommend specific projects –Describes generic projects to enhance TVLs –Leaves specific project recommendations to TPs Caveats for Phase 3 Report

20 TVL is a real issue; –Impediment to transfer imbalance energy and regulation between BAs; –Will limit where & how the region can integrate wind; –Limits can be raised, but not overnight. Need for TVLs will vary by system; Should plan for increased transmission flexibility to manage the increasingly variable flows on grid Bottom Line – so far

21 How automated is your RAS arming? How much automatic voltage control do you have across your system? What are the TVLs for your major flowgates? How will your company manage TVLs? What capital projects are planned to increase Transmission Flexibility? Questions for Companies

22 Modifying some SOL assumptions (e.g. overshedding); Automating RAS Automating voltage control Ensure voltage control equipment is designed for frequent switching (**Detailed TVL studies needed to identify most effective solutions) Options for increasing TVLs

Questions?