TSS Wind Generation Task Force Report

1. Technical Studies Subcommittee August 15-17, 2007Seattle, Washington TSS Wind Generation Task Force Report Craig Quist, PE PacifiCorp, Transmission Planning Salt Lake City, Utah

2. What is the Status of the VRT Standard?

3. The VRT white paper approved with comments at May 25, 2007 - Special TSS Meeting. The final paper forwarded to TSS Chairman (Tom Green) on June 13, 2007. Shortly afterwards, the VRT white paper was posted on WECC website and TSS, RS and PCC were informed of posting. On June 1, Craig Quist emailed AWEA that his was not available to speak at AWEA Interconnection Working Group Session on June 4, and provided a summary of the anticipated WECC process. June 1, Rob Gramlich (AWEA Policy Director) emailed NERC indicating that the Wind Industry preferred a National standard and believed FERC would as well. June 4, Don Benjamin (NERC Director of Operations) forward question to Gerry Adamski (NERC Director of Standards) concerning if NERC should develop a VRT Standard based on WECC VRT White Paper. June 25, NERC Staff asked the WECC Staff (Ken Wilson) to provide the status of WECC VRT Standard. What is the Status of the VRT White Paper?

4. June 25, WECC Staff provided status to NERC July 3, NERC indicates VRT could have continent-wide applicability. Asks if those pushing effort within WECC could sponsor a NERC SAR? July 3, RS Chairman asked by WECC Staff about sponsorship of NERC SAR. July 3, PCC Chair requests inputs from standing committee chairs. July 10, JGC recommended that NERC take lead in development of VRT Standard. About this time period, CQ asked, what is happening with Standard? July 17, CQ and CT are nominated to be on PRC-024 Generator Verification Drafting Team representing WECC. August 16 – RS will review the VRT White Paper. Recommendation will be made to move forward with developing a new WECC criteria based on white paper. What is the Status of the VRT White Paper?

5. What is the Status of the VRT White Paper? Questions?

6. Inconsistent WECC Requirements for Wind Plants: Reactive and Voltage Control

7. Inconsistent WECC Requirements for Wind Plants • Within WECC, there appears to be an inconsistent application of interconnection requirements when it comes to the use of voltage and reactive control for large wind generation facilities.

8. Source: NERC/WECC Planning Standards WECC Minimum Operating Criteria (April 2005) Standards [page 75] S1. All synchronous generators connected to the interconnected transmission systems shall be operated with their excitation system in the automatic voltage control mode unless approved otherwise by the transmission system operator. From Section 1 - Generation Control and Performance B. Voltage and Reactive Control 5. Generators. Generating units 10 MVA and larger shall be equipped with automatic voltage control equipment. All generating units with automatic voltage control equipment shall normally be operated in voltage control mode. These generating units shall not be operated in other control modes (e.g., constant power factor control) unless authorized to do so by the host control area. The control mode of generating units shall be accurately represented in operating studies. Key Points Synchronous generators connected to the transmission system shall be operated with their excitation system in the voltage control mode. Generating units 10 MVA and larger shall be equipped with automatic generation control equipment. All generating units with automatic voltage control equipment shall normally be operated in voltage control mode. The control mode of generating units shall be accurately represented in operating studies. 1. WECC Minimum Operating Criteria

9. Source: RMS_Criteria_Agreement_with_ 6th_ Amendment _11-01-06.pdf Western Electricity Coordinating Council FERC Electric Tariff, First Revision No. 1 IV. RELIABILITY CRITERIA APPLICABLE TO GENERATORS Automatic Voltage Regulators (“AVR”) 2. WECC Criterion Automatic voltage control equipment on synchronous generators shall be kept in service at all times, unless on of the exemptions listed in Section IV.A.4 (Compliance Standard) applies, with outages coordinated to minimize the number out of service at any one time. All synchronous generators with automatic voltage control equipment shall normally be operated in voltage control mode and set to respond effectively to voltage deviations. Key Points Automatic voltage control equipment on synchronous generators shall be kept in service at all times… with outages coordinated to minimize the number out of service at any one time. All synchronous generators with automatic voltage control equipment shall normally be operated in voltage control mode and set to respond effectively to voltage deviations. 2. Automatic Voltage Regulation

10. Source: FERC Order 661 – Appendix G Interconnection Requirements for a Wind Generating Plant. ii. Power Factor Design Criteria (Reactive Power) A wind generating plant shall maintain a power factor within the range of 0.95 leading to 0.95 lagging, measured at the Point of Interconnection as defined in this LGIA, 20050602-3073 Issued by FERC OSEC 06/02/2005 in Docket#: RM05-4-000 if the Transmission Provider’s System Impact Study shows that such a requirement is necessary to ensure safety or reliability. The power factor range standard can be met by using, for example, power electronics designed to supply this level of reactive capability (taking into account any limitations due to voltage level, real power output, etc.) or fixed and switched capacitors if agreed to by the Transmission Provider, or a combination of the two. The interconnection Customer shall not disable power factor equipment while the wind plant is in operation. Wind plants shall also be able to provide sufficient dynamic voltage support in lieu of the power system stabilizer and automatic voltage regulation at the generator excitation system if the System Impact Study shows this to be required for system safety or reliability. Key Points A wind generating plant shall maintain a power factor within the range of 0.95 leading to 0.95 lagging, measured at the Point of Interconnection… if the Transmission Provider’s System Impact Study shows that such a requirement is necessary to ensure safety or reliability. The interconnection Customer shall not disable power factor equipment while the wind plant is in operation. Wind plants shall also be able to provide sufficient dynamic voltage support in lieu of the power system stabilizer and automatic voltage regulation at the generator excitation system… if the System Impact Study shows this to be required for system safety or reliability. 3. FERC Order 661–Appendix G (Wind Interconnect)

11. Source: FERC Order 661 Commission Conclusion - Power Factor Range and General Application of the Requirement 55. In response to those who assert that adherence to the voltage schedule is more important than merely maintaining a power factor within the specified range, we note that article 9.6.2 of the LGIA already requires that the “Interconnection Customer operate the Large Generating Facility to maintain the specified output voltage or power factor at the Point of Interconnection.” This language applies to wind plants and addresses this concern. Key Points Article 9.6.2 of the LGIA already requires that the “Interconnection Customer operate the Large Generating Facility to maintain the specified output voltage or power factor at the Point of Interconnection.” This language applies to wind plants and addresses this concern. 4. FERC Order 661 - Power Factor Range

12. Inconsistent WECC Requirements for Wind Plants • Feedback from Abraham Ellis (PNM): • This is interesting, especially the last paragraph.  It suggests that, according to FERC, LGIA section 9.6.2 (voltage control) applies to wind farms.  However, the ability to hold a voltage schedule depends on the design power factor range as defined in LGIA section 9.6.1.  That section specifically says that the +/-0.95 power factor design criteria does not apply to wind generators. 

13. Abraham Ellis Transmission Operations Public Service Company of New Mexico Southwest Renewable Energy Conference August 2007 – Boulder, CO Wind Interconnection Stories

14. Huh? Reactive Power is Not Imaginary What Is The Standard – Go Figure! • FERC Order 661A Power Factor (PF) Design Criteria (Reactive Power), under the “wind generators are different” philosophy • Shall maintain a power PF within a range of +/- 0.95 at the POI… if the System Impact Study (SIS) shows that this is needed for safety or reliability • Shall be able to provide dynamic voltage support… if (or to the extent that) the SIS shows that this is required for safety or reliability (Note: requirement is at POI, not WTG terminals) • Some variations exist in different jurisdictions • ERCOT, Canada, Europe

15. Reactive Power is Not Imaginary Var Requirement – Issues • Interpretation of PF requirements not clear • Amount and type of reactive power (static/dynamic) needed varies with system conditions, & over time • SIS does not cover all possible conditions • In recent cases, the full +/-0.95 PF capability at the POI has been “presumed” to be required • In actual operation, steady-state control can vary • Power factor control – Maintain PF near a target • Reactive control – Maintain VAr output near a target • Voltage control – Maintain voltage schedule at a bus • LVRT some times dictates need for external dynamic reactive power support

16. Reactive Power is Not Imaginary Var Requirement – Issues • WTG contribution to steady-state reactive control • WTGs usually operated in PF control mode • In some cases, ability to use WTG capability for steady-state voltage control is restricted by patents • External source/controller are sometimes installed if voltage control is required, regardless of WTG capability • Transient performance is another story – WTG can switch from PF to voltage control during a low voltage transient • Implications for interconnection studies • Understand interconnection requirement • Understand WTG capability on paper and in practice; model accordingly

17. Inconsistent WECC Requirements Wind Plants Preliminary Recommendations • Assuming our goal is to provide for consistent application of interconnection requirements as well as to promote the use of voltage control for large wind generation facilities, the NERC/WECC Planning Standards need to be modified to provide a foundation that supports this endeavor. • For example, Section 1.B.5 (Voltage and Reactive Control) could be modified to include the requirement that “Generating units 10 MVA and larger, and generation facilities with net generation of 20 MVA or greater, shall be equipped with automatic voltage control equipment.” • With respect to wind generation facilities operating with a fixed power factor: • this may mean automatic removal of power factor correction capacitors when the monitored voltage rises above a specified level, or • systematically adding power factor correction capacitors when the monitored voltage falls below a specified level – if appropriate and regardless of the effect on the power factor.

18. Inconsistent WECC Requirements Wind Plants • Where do we go from here with this information… • Have a conference call with the WGTF for the purpose of: • Discussing additional inputs to the inconsistencies • Polish Presentation (Next TSS Meeting) • Develop an action for TSS Chair to take to the JGC • Anticipate changes to document to add clarity. • The following question will need to be raised to BOD: Should WECC make a recommendation to FERC to resolve inconsistencies in FERC Orders – concerning wind generation interconnection requirements?