Transmission-Distribution Interface Working Group Meeting June 21, 2017

Today’s Agenda: Introductions Brief updates on related efforts (15 minutes): White Paper published + upcoming outreach CPUC Grid Modernization – June 5 ESDER FERC Storage/DER Rulemaking Other? Presentation on CPUC/CAISO Multi-Use Application Staff Proposal (30 minutes) – Lorenzo Kristov, CAISO Implications on operations at T-D interface Discussion of relevance to WG efforts Working Group Exercise: Two Master Problem: Evaluating Conflicts When Providing Wholesale AND Distribution Services (90 minutes) – Matthew Tisdale, MTS Lunch Break (30 minutes) Presentation on Implementation of Use Cases A & B + Discussion (60 minutes) -- Mark Esguerra, PG&E Presentation on Stem deployments and perspective from NYISO (30 minutes) – Ted Ko, Stem Discuss future meeting dates, meeting agendas, and next steps (15 minutes) Surprise sendoff

Orientation to 2017 Work Plan Prepare an initial white paper that summarizes the 2016 effort, including description of existing coordination procedures, anticipated operational challenges with high DER, and communication and coordination improvements identified to date Educate the WG on grid modernization from IOU perspective (using 1/24 DRP workshop presentations) and consider implications of operational coordination needs on grid modernization Develop example use-cases reflecting likely DER integration scenarios to ground discussion in practical implications. Consider how future pilot proposals may stem from identified use cases. Specify potential real-time coordination procedures to manage potential conflicts between DO needs and ISO dispatches. Begin with scenario approach and then broaden as needed Identify principles for a DO approach to DER curtailment resulting from distribution level constraints Consider any unique perspectives or challenges for municipal utilities w/in ISO footprint Describe the process and timeline for integration of a new DERA into the wholesale market, including utility process for 30-day review of DERA under ISO DERP tariff as well as ISO integration process Develop methods for short-term DER forecasting and impacts at T-D Interface (IOUs) Develop method for DO feasibility assessment of ISO’s day-ahead DER schedules and real-time dispatches Explore how various DSO models would impact design of the T-D interface coordination framework

The Two Masters Problem: Problem Definition: Will DER receive competing dispatch signals from wholesale and distribution service operators? If so, how will the conflict be resolved? Identified by working group members as a priority question at May meeting. Agreed to further consideration by matrix of services and situations, allowing for identification of potential conflicts. The following draft matrix created by AMS and MTS. The following exercise intended to facilitate population of the matrix.  

Distribution - Wholesale Grid Services Conflict Matrix Two Masters? Distribution - Wholesale Grid Services Conflict Matrix Distribution Services   Wholesale Services Energy Regulation Up Regulation Down Spinning Reserve Non-Spinning Reserve Energy Up Energy Down Capacity Up Capacity Down VAR Up VAR Down

Working Group “Conflict Identification and Resolution” Exercise: Steps: Hold hands Discuss threshold questions on next slide, level-set Populate matrix by identifying conflicts Populate matrix by identifying opportunities Think, Repeat Behold  

Does the following correctly state the task at hand? Threshold Questions: Does the following correctly state the task at hand? The Working Group is analyzing when providing two or more services — one at wholesale, one at distribution — could result in a DER receiving conflicting dispatch signals. There are some situations where a conflict would be created between two dispatch signals for two services, while the same two services may not create a conflict in other situations. Our task is to identify the situations where conflicts exist and for which services. Identified conflicts would be the same under Use Cases C-1, C-2, D-1, and D-2. Conflicts are not resolved through bifurcated capacity or aggregations. Use Cases E and F considered at a later date. Correct? Matrix enables analysis of conflicts between wholesale and distribution services identified in most recent version of “T-D Interface Working Group Use Cases.” Customer services (e.g., demand charge management) and RA not included. Correct? Other questions?

PG&E DO Activities Assessing High DER Penetration Use Cases Distribution Operations performed assessment of high DER penetration feeders Identify any impacts to operation of distribution grid Discuss key operational considerations for assessing high DER penetration feeders Selected two feeders in PG&E system that are currently experiencing high penetration of DERs Feeder Name Feeder ID Feeder Capacity (MW) Peak Load (MW) Average Node ICA (kW) Feeder ICA (kW) Penetration DG Customers Feeder A 103441101 12.33 6.63 569 2,565 120% 127 Feeder B 152811105 6.09 3.38 356 798 114% 98

High DER Penetration Preliminary Screening Criteria applied

Examples of Existing Use Case A in PG&E System October 2013 October 2016 Market participation of large DERs providing regulation complicates online power flow calculations and makes load forecasting very difficult DERs providing regulation service may have multiple changes in power flow direction For specific circuit, DER penetration level relatively low and is considered to be a robust feeder. Therefore, no voltage or power quality issues recorded Managing and Integrating 3rd party DER aggregations into utility systems has proven to be very complex technically. Standards are immature and business rules are not yet established for distribution services. 4MW Battery Output October 2016

Background Slides

Services in Red have been preliminarily deemed “reliability” Source: CPUC, June 2 Workshop Presentation

Use Cases Use Case Configuration Grid Services Provided A Single Resource Wholesale (only) B Aggregated Resource – consider single-feeder and multi-feeder sub-cases C-1 Wholesale + Distribution using separate portions of capacity for each (Multiple Use Application) C-2 Wholesale + Distribution using the same capacity D-1 D-2 Aggregated Resource E Wholesale + Distribution: enhanced DO/DSO functionality F