Reactive Power Coordination Workshop Alex Sills Senior Operations Engineer Freddy Garcia Operations Planning Supervisor Stephen Solis System Operations Improvement Manager ERCOT Public July 24, 2017

Antitrust Admonition Antitrust Admonition Antitrust Admonition To avoid raising concerns about antitrust liability, participants in ERCOT activities should refrain from proposing any action or measure that would exceed ERCOT’s authority under federal or state law. For additional information, stakeholders should consult the Statement of Position on Antitrust Issues for Members of ERCOT Committees, Subcommittees, and Working Groups, which is posted on the ERCOT website.1 Disclaimer All presentations and materials submitted by Market Participants or any other Entity to ERCOT staff for this meeting are received and posted with the acknowledgement that the information will be considered public in accordance with the ERCOT Websites Content Management Operating Procedure.

Introductions Presenters Around the Room Alex Sills Freddy Garcia Senior Operations Engineer Freddy Garcia Operations Planning Supervisor Stephen Solis System Operations Improvement Manager Around the Room

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A Presenter Stephen Solis System Operations Improvement Manager ERCOT Public July 24, 2017

Reactive Coordination Conducted by ERCOT and ERCOT Transmission Operators Several new ERCOT Transmission Operators established in past few years Renewable generation capacity has grown and continues to grow NERC Requirements continue to change

Problem Statement The integration of renewable generation within the ERCOT interconnection has introduced several new Transmission Operators and fundamentally altered the generation dispatch pattern in the region. A new tool is needed to address multiple interrelated objectives of coordination of voltage and reactive control between TOs, maintaining reliability by preventing and or correcting System Operating Limit (SOL) exceedances, minimizing cost of maintenance resulting from increased switching, and maintaining or improving transfer capability.

Reactive Power Coordination “Tool” ERCOT is actively working on a project to develop a multi hour look ahead tool to improve reactive power coordination within the ERCOT region. This tool is being called the Reactive Power Coordination (RPC) tool. The RPC tool will optimize reactive power controls (shunt devices, Generator Voltage Set Points, Static Var Compensators (SVCs), etc.) across a multi-hour interval to resolve reactive power and voltage-related constraints (voltage limits, temporal constraints, reactive reserves, etc.) under both normal and contingency conditions.

Reactive Power Coordination “Tool” The RPC tool will have 3 “modes”. Daily study that optimizes the same window as Daily Reliability Unit Commitment (RUC). Hourly study that optimizes across the next 12 hours. Offline study mode capable of optimizing up to 48 hours. The Daily study reactive dispatch will be more informational in nature to identify needs for additional coordination or correction. The Hourly study will be more accurate and give a 12 hour rolling window of expected reactive controls dispatch. The Offline study mode will allow scenario testing as necessary (e.g. severe weather) and potentially serve as a backup study mode if the normal study mode is unavailable.

RPC Tool Objectives Minimize the number of control actions. Minimize the “cost” / prioritization of control actions. Maintain adequate and or potentially maximize transfer capability on stability limit interfaces during instances of low stability margin Solve all constraints possible and identify any unresolved constraints.

RPC Tool Inputs Hourly power flow cases Constraints Load Forecast Wind/Solar Forecast RUC/COP data Outages DC Tie schedules Constraints Physical Temporal Contingency definitions Remedial Action Scheme definitions Historical information Previous hours switching information for temporal constraints

RPC Tool Constraints System voltage limits Dynamic reactive reserves Normal (Pre-contingency) Emergency (Post-contingency) Dynamic reactive reserves Voltage stability limits Physical constraints (e.g. reactive capability curves for generation resources, reactive capability of SVC, AVR status etc.) Temporal constraints (e.g. startup time, minimum run time, max # of operations within 24 hours, etc.)

RPC Tool Controls Static reactive resources Dynamic reactive resources Shunts Reactors Capacitors Transformer control taps Dynamic reactive resources SVCs STATCOMs Synchronous Condensers Generating Units Unit Commitment, Line Switching, Distribution side reactive power, Load Shed plans will be handled as needed if RPC tool cannot solve a constraint.

RPC Tool Controls prioritization The RPC tool will have the ability to take into consideration the different objective functions and constraints by setting the appropriate control “cost” (priority and weighting factors). ERCOT staff will have to maintain and “tune” these control “costs”. Ex’s below: change the weighting assigned to different objective functions change a minimum requirement of reactive power reserve for sub-regions of the ERCOT area disable or enable selected control devices/options

Single Point vs Multi-Hour Optimization Single Point in time (future or real time) reactive optimization has many well proven solutions. Running real time reactive optimization is effective in addressing constraints but has shown to increase the control actions (i.e. switching actions) to adjust to every new optimization execution. Multi-Hour Optimization will minimize or reduce the number of control actions. Multi-Hour Optimization is not a new concept, however Multi-Hour Optimization of reactive power has not been previously implemented due to the very complex calculations necessary to solve the mixed-integer non-linear programming (MINLP) optimization problem.

Coordination between ERCOT and TOs Project Implementation Coordinate on necessary constraints for the RPC tool (e.g. Survey) Coordinate on necessary “cost”/weighting factors for control selection in the RPC Tool Coordinate on the RPC tool reactive dispatch output file design Rule Changes Coordinate and implement any necessary changes to ERCOT Protocols Coordinate and implement any necessary changes to ERCOT Operating Guides Testing Manual review of RPC tool reactive dispatch for issues Pilots and tests of implementing actual RPC tool reactive dispatch

Time Frame ERCOT expects to have a prototype RPC tool ready by Q1 2018. ERCOT expects integrating the prototype into production systems will take 6-12 months Q4 2018 to Q2 2019. ERCOT expects to test or pilot results for 3 to 6 months to stabilize and build confidence in the reactive dispatch. ERCOT will need to coordinate any rule changes or modeling expectations to support long term maintenance of temporal constraints and tuning of the reactive dispatch.

Q&A

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A ERCOT Public July 24, 2017

We will return at 10:45 AM.

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A Presenter Alex Sills Senior Operations Engineer ERCOT Public July 24, 2017

Previous Survey for AVR Details ERCOT requested information and incorporated data into network model regarding AVR functionality of static reactive devices (shunts and LTCs) in 2015-2016 Information gathered: Instantaneous Auto Operation? Time Delayed Auto Operation? Manual SCADA Operation? *highly pertinent for temporal constraints Target KV range for auto operation? Breaker isolation after fault? (w/ breaker identification) Additional comment field

Previous Survey Screenshot

Goal: RPC Schedule guides Real-time Operations Logistical and physical limitations regarding operation of static reactive equipment needs to be made available for RPC tool as temporal constraint data Data required for Shunts and LTCs Lead times for control actions Timeouts between control actions Maximum # of control actions per period of time Assumption SVCs, STATCOMs, Sync Condensers have no temporal constraints Concerns here?

New Survey Mock-up Screenshot

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A ERCOT Public July 24, 2017

We will return at 1:00 PM.

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A Presenter Alex Sills Senior Operations Engineer ERCOT Public July 24, 2017

RPC Output Output data required Device identification Hourly schedule Station name Device ID Breaker association is possible, but could present issues with multiple shunts mapped to same control breaker Hourly schedule Status (shunts) Setpoint (LTCs/SVCs/Units) Other data Summary # of control actions for each device Other requirements/suggestions?

RPC Output Mock-up Screenshot

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A Presenter Freddy Garcia Operations Planning Supervisor ERCOT Public July 24, 2017

Voltage Set Points NPRR 776 implements requirements for transparency of both the actual measured value and desired Set Point for the Point of Interconnection (POI) voltage between all affected entities (TO, ERCOT, QSE, and RE). ERCOT is working to leveraging existing telecommunications infrastructure (e.g. ICCP) to minimize additional expenses. ERCOT will have a majority of Voltage Set Point work (NPRR 776) in place by 1Q of 2018. Working towards making points available to QSEs by Dec 2017. Generator Voltage Set Points is a control that the RPC tool will be utilizing to achieve its optimized output.

Voltage Set Points – Current State

Voltage Set Points – Post NPRR 776 implementation

Voltage Set Points TSPs will be associating the two ICCP points (Set Point and actual) and generator relationships to the POI kV Measurement device (e.g. on busbar, line, xfmer). ERCOT will be using the relationships in its EMS to map and make available the ICCP points to the appropriate QSE. QSEs are required to send the two ICCP points (Set Point and actual POI kV) to the appropriate Generation Resource. Naming convention should remain for kV measurements, set points/targets should be same but have a _kvt suffix instead of _kv. ERCOT will update the ICCP Handbook to reflect naming convention for defined points for QSE and TSP.

Voltage Set Points There are some POI kV measurements that do not currently exist (approximately 14). TSP must install POI kV measurements and are providing feedback to ERCOT on when that will occur. Existing change management practices will allow for these Voltage Set Points to move to the appropriate QSE when a QSE to Generation Resource relationship changes.

Voltage Set Points The RPC tool will utilize Generator Voltage Set Point changes as a control. The RPC tool will initially have the Generator Voltage Set Point corresponding to the seasonal Voltage Profile. This control will have more “cost” or “weighting” than switching shunt reactive devices. ERCOT needs to coordinate the maximum number of Generator Voltage Set Point changes that should occur within a given period of time. ERCOT needs to coordinate the minimum change quantity (e.g. 1kV) that Generator Voltage Set Point changes should occur.

Q&A

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A ERCOT Public July 24, 2017

We will return at 2:15 PM.

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A Presenter Freddy Garcia Operations Planning Supervisor ERCOT Public July 24, 2017

Reactive Reserves What are Reactive Reserves Static Dynamic Blue = Wind Reactive Lt Grn = Gen Reactive Yellow = TSP Caps Drk Grn = Wind Caps

Reactive Clusters/Zones Why we need zones Identify zones Monitor Reactive zones in Real-Time RPC with Reactive reserves as a constraint Shifts priorities from reducing control actions to preserving dynamic reactive reserves and maximizing transfer capability

Reactive Reserves

Voltage Stability Limits Location of Reactive devices matters Optimization & sensitivities Fast responding Dynamic Reactive to arrest voltage events Maintaining stiff voltage in reactive zone will improve import stability limits

Interrelation between Stability Limit and solution Circular relationship between the optimized reactive solution and voltage stability limits. Solution affects the limits which dynamically changes a constraint which may affect the solution.

Q&A

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A ERCOT Public July 24, 2017

We will return at 3:00 PM.

Reactive Power Coordination Workshop Reactive Power Coordination (RPC Overview) Break Temporal Constraints / Survey Lunch RPC Output Voltage Set Point (NPRR 776) Reactive Reserves / Voltage Stability Limits Wrap Up/Discussion/Q&A Presenter Stephen Solis System Operations Improvement Manager ERCOT Public July 24, 2017

Wrap-up ERCOT is working to develop an ERCOT system Reactive Power Coordination (RPC tool). ERCOT will be sending out a survey to acquire temporal constraints that will be input to RPC tool. ERCOT will be coordinating with ERCOT TOs to make the output of the tool as meaningful and user friendly as possible. ERCOT will have a majority of Voltage Set Point work (NPRR 776) in place by 1Q of 2018. ERCOT will be incorporating dynamic reactive reserves and voltage stability limits as constraints within the RPC tool.

Discussion / Q&A