Western Electricity Coordinating Council PWG Review Summary James Wells – PWG Chair Western Electricity Coordinating Council

PWG Membership Changes James Wells: LADWP New PWG Chair Craig Figart: Avista New PWG Vice Chair Don Badley: NWPP Planned retirement January 2, 2018 Planned replacement Greg Park Rick Lowther: SRP Planned retirement January 1, 2018 Planned replacement pending Western Electricity Coordinating Council

Western Electricity Coordinating Council BAL-004-0 Retirement FERC Approved Contingent on retirement of NAESB WEQ-006 Manual TEC Business Practice Standard Peak RC clocks upgraded and ready to capture larger accumulated TE. Peak RC can transmit accumulated TE via ICCP if needed by entities Delta TE still required to be tracked for WI BAL-004-WECC-2 ATEC NERC to publish formal communication and transition Western Electricity Coordinating Council

Western Electricity Coordinating Council WECC-0124 SAR Status Reduced scope: Only addressing R1 regarding PII reconciliation to WIT tool No longer pursuing reduction to PII accumulation limits Entities felt reducing limits on accumulated PII was an issue of equity, not reliability Ballots Close August 25, 2017 Western Electricity Coordinating Council

BAL-002-WECC-2 Field Trial 18 DCS events since implementation of Field Test (May 1, 2017) 100% pass rate of DCS events PWG will be evaluating Frequency Response during events PWG gathering data as proof there is no impact to reliability Field Test planned for 1 year data collection May be extended until FERC approval of BAL-002-WECC-2 R2 retirement Western Electricity Coordinating Council

BAL-002-WECC-2 Field Trial DCS Events Entity # # DCS Events Average Loss (MW) Average Contingency Reserve Obligation (MW) Average Spin (MW) % Pass Entity 1 N/A Entity 2 3 509 554 400 100% Entity 3 1 480 585 1165 Entity 4 Entity 5 22 519 3135 5246 700 MW+ Events Entity # Events 700 MW + Average Loss (MW) Entity 1 N/A Entity 2 Entity 3 Entity 4 2 758 Entity 5 4 851.75 Western Electricity Coordinating Council

Western Electricity Coordinating Council BAL-003-1.1 SAR NERC level drafting team Evaluating C point to B point frequency response Used in calculation to determine IFRO Lowest frequency seen during event is sometimes achieved after Point C (measured at t+12 seconds). Potential impact to the nadir point, the B to C ratio and calculated IFRO Evaluating reporting and collection for FRSG Few details are know regarding specific proposal, PWG will continue to review postings and advise WECC membership. Western Electricity Coordinating Council

Western Electricity Coordinating Council BAL-003-1.1 SAR Western Electricity Coordinating Council

PII - Ramp Calculations PWG believes that the current PII calculation performed by the WIT could be open to interpretation based on the NERC Glossary definitions. The WIT uses an e-tag based hourly NIS component along with an hourly NIA component, the later supplied by the BA, to calculate Inadvertent Interchange and subsequently, hourly PII. Components of the Primary Inadvertent Interchange (PII) calculation include: the BA frequency bias value used in their ACE equation, the sum of all Western Interconnection BA frequency bias values, hourly time error change, and hourly NIA and NIS. The WIT uses an e-tag based hourly NIS component along with an hourly NIA component, the later supplied by the BA, to calculate Inadvertent Interchange and subsequently, hourly PII. For the NIS component, the WIT aggregates hourly scheduled interchange MWh values that are derived from the MW level and nominal start/stop times of the e-tag MW profiles, ignoring the effect of schedule ramping. This type of block MWh accounting is an accepted practice in energy accounting systems and has little effect on their accuracy because energy amounts associated with schedule start and stop ramps net to zero over the longer energy accounting daily, weekly or monthly time periods. However, the result of ignoring schedule ramping in the IS calculation causes a BA that perfectly controls to the aggregated MW profiles prescribed by the e-tags that make up its NIS profile to nevertheless accrue Inadvertent Interchange. And, because the time error change, that is a factor in the hourly PII calculation, varies hour-by-hour, these PII errors do not net to zero. PWG believes that the current Primary Inadvertent Interchange calculation performed by the WIT does follow the latest NERC Glossary definitions . The definition of NIs was changed to: The algebraic sum of all scheduled megawatt transfers, including Dynamic Schedules, to and from all Adjacent Balancing Authority areas within the same Interconnection, including the effect of scheduled ramps. Western Electricity Coordinating Council

PII – Ramp Calculations Illustrates an e-tag’s scheduled interchange MW profile and the difference between the hourly MWh values calculated according to the typical energy accounting system method and those obtained by accounting for schedule ramping. Components of the Primary Inadvertent Interchange (PII) calculation include: the BA frequency bias value used in their ACE equation, the sum of all Western Interconnection BA frequency bias values, hourly time error change, and hourly NIA and NIS. The WIT uses an e-tag based hourly NIS component along with an hourly NIA component, the later supplied by the BA, to calculate Inadvertent Interchange and subsequently, hourly PII. For the NIS component, the WIT aggregates hourly scheduled interchange MWh values that are derived from the MW level and nominal start/stop times of the e-tag MW profiles, ignoring the effect of schedule ramping. This type of block MWh accounting is an accepted practice in energy accounting systems and has little effect on their accuracy because energy amounts associated with schedule start and stop ramps net to zero over the longer energy accounting daily, weekly or monthly time periods. However, the result of ignoring schedule ramping in the IS calculation causes a BA that perfectly controls to the aggregated MW profiles prescribed by the e-tags that make up its NIS profile to nevertheless accrue Inadvertent Interchange. And, because the time error change, that is a factor in the hourly PII calculation, varies hour-by-hour, these PII errors do not net to zero. PWG believes that the current Primary Inadvertent Interchange calculation performed by the WIT does follow the latest NERC Glossary definitions . The definition of NIs was changed to: The algebraic sum of all scheduled megawatt transfers, including Dynamic Schedules, to and from all Adjacent Balancing Authority areas within the same Interconnection, including the effect of scheduled ramps. Western Electricity Coordinating Council

PII - Ramp Calculations The result of ignoring schedule ramping in the IS calculation causes a BA that perfectly controls to the aggregated MW profiles prescribed by the e-tags that make up its NIS profile to nevertheless accrue Inadvertent Interchange. And, because the time error change, that is a factor in the hourly PII calculation, varies hour-by-hour, these PII errors do not net to zero. Components of the Primary Inadvertent Interchange (PII) calculation include: the BA frequency bias value used in their ACE equation, the sum of all Western Interconnection BA frequency bias values, hourly time error change, and hourly NIA and NIS. The WIT uses an e-tag based hourly NIS component along with an hourly NIA component, the later supplied by the BA, to calculate Inadvertent Interchange and subsequently, hourly PII. For the NIS component, the WIT aggregates hourly scheduled interchange MWh values that are derived from the MW level and nominal start/stop times of the e-tag MW profiles, ignoring the effect of schedule ramping. This type of block MWh accounting is an accepted practice in energy accounting systems and has little effect on their accuracy because energy amounts associated with schedule start and stop ramps net to zero over the longer energy accounting daily, weekly or monthly time periods. However, the result of ignoring schedule ramping in the IS calculation causes a BA that perfectly controls to the aggregated MW profiles prescribed by the e-tags that make up its NIS profile to nevertheless accrue Inadvertent Interchange. And, because the time error change, that is a factor in the hourly PII calculation, varies hour-by-hour, these PII errors do not net to zero. PWG believes that the current Primary Inadvertent Interchange calculation performed by the WIT does follow the latest NERC Glossary definitions . The definition of NIs was changed to: The algebraic sum of all scheduled megawatt transfers, including Dynamic Schedules, to and from all Adjacent Balancing Authority areas within the same Interconnection, including the effect of scheduled ramps. Western Electricity Coordinating Council

PII - Ramp Calculations Doing Proof of Concept with data from May & June 2017 data from PWG member BA Sample data, sample months How are sample entities impacted (positive/negative) If there is merit and supported by sample data, PWG would then expand the analysis to more BAs over a longer timeframe and produce a report summary with recommendations to EPAS/OC. With approval, it would then be coordinated with WIT User Group to request changes from OATI to WIT Components of the Primary Inadvertent Interchange (PII) calculation include: the BA frequency bias value used in their ACE equation, the sum of all Western Interconnection BA frequency bias values, hourly time error change, and hourly NIA and NIS. The WIT uses an e-tag based hourly NIS component along with an hourly NIA component, the later supplied by the BA, to calculate Inadvertent Interchange and subsequently, hourly PII. For the NIS component, the WIT aggregates hourly scheduled interchange MWh values that are derived from the MW level and nominal start/stop times of the e-tag MW profiles, ignoring the effect of schedule ramping. This type of block MWh accounting is an accepted practice in energy accounting systems and has little effect on their accuracy because energy amounts associated with schedule start and stop ramps net to zero over the longer energy accounting daily, weekly or monthly time periods. However, the result of ignoring schedule ramping in the IS calculation causes a BA that perfectly controls to the aggregated MW profiles prescribed by the e-tags that make up its NIS profile to nevertheless accrue Inadvertent Interchange. And, because the time error change, that is a factor in the hourly PII calculation, varies hour-by-hour, these PII errors do not net to zero. PWG believes that the current Primary Inadvertent Interchange calculation performed by the WIT does follow the latest NERC Glossary definitions . The definition of NIs was changed to: The algebraic sum of all scheduled megawatt transfers, including Dynamic Schedules, to and from all Adjacent Balancing Authority areas within the same Interconnection, including the effect of scheduled ramps. Western Electricity Coordinating Council

Patterns of Frequency Deviation PWG is evaluating time of day patters for frequency deviation Appears to mimic PV solar production with distinct increases or decreases in frequency during solar ramps PWG will be exploring these trends further and with more depth Solar generation Wind generation ACE Inertia (Wester Interconnection, Southern Area vs Northern Area) Western Electricity Coordinating Council

Patterns of Frequency Deviation Western Electricity Coordinating Council

Interconnection Performance PWG evaluating performance related to large frequency deviations Assess Frequency events that exceed Frequency Trigger Limit (FTL) for 10 minutes or reoccurs again within 10 minutes FTL = +/- 0.068Hz (59.932 Hz / 60.068 Hz) Western Electricity Coordinating Council

Western Electricity Coordinating Council Loss of PDCI PWG will be reviewing PDCI trips that have occurred in the past few months. Some have resulted in extended suppressed frequency Evaluate schedule cuts with respect to PDCI trips Frequency, PDCI Power Order, PDCI Schedules, ACE Can lessons learned be identified? Should best practices or guidelines be developed to improve WI control performance? Western Electricity Coordinating Council

Western Electricity Coordinating Council ERSWG Measures Essential Reliability Service Work Group Measures Voltage Control Frequency Response Load and Resource Balancing Inertia Trends over time as generation portfolio changes Net Ramp and Demands Curves Rate of Change of Frequency (RoCoF) Western Electricity Coordinating Council

WECC Performance Charts Western Electricity Coordinating Council

WECC Performance Charts Western Electricity Coordinating Council

WECC Performance Charts Western Electricity Coordinating Council

WECC Performance Charts Western Electricity Coordinating Council

WECC Performance Charts Western Electricity Coordinating Council

Western Electricity Coordinating Council PWG Charter Review Reviewed and Updated the PWG Charter PWG is looking for WECC Board Approved Closed Door Session Motion Resolved that the WECC Event and Performance Analysis Subcommittee hereby approves the Performance Work Group Charter. Western Electricity Coordinating Council