DER Implications for the Transmission System

Transcription

1 DER Implications for the Transmission System NERC SPIDERWG Meeting, January 8-9, 2019 Texas RE, Austin, Tx Jameson Thornton, PG&E Grid Innovation & Integration

2 Outline Background Context (Service Territory) Definitions (DER) DER changes and challenges So what? Why does it matter?

3 PG&E Stats Peak Demand: ~ 20,000 MW Service Territory: 70,000 sq miles ~5 million customers 15 million people Total Transmission: 18,600 miles

4 Distributed Energy Resources (DERs) DERs fit into 5 categories Distributed Generation (DG) Energy Efficiency (EE) Demand Response (DR) Electric Vehicles (EVs) Energy Storage Source Source Source Sink Source/Sink?

5 What is changing? Load Forecast Accounting for DERs (DG, EE, DR, EV, Storage) Modeling As of 2018, this is already incorporated (upcoming slide) Scenarios and studies Critical times of system stress are not always the traditionally determined times What does this mean for studies?

6 CEC Lowered 2026 Demand Forecast by 3,770 MW

7 DG impact on demand System Load Vs. PV Output PG&E System Load (MW) 22,000 20,000 18,000 16,000 14,000 Net Load Gross Load Future Load? Solar Output 2,500 2,000 1,500 1,000 PV output (MW) 12, , :00 2:00 3:59 5:59 7:59 9:59 11:59 13:59 15:59 17:59 19:59 21:59 23:59 Time

8 ~4,000 MW of Interconnected DG at PG&E

9 Load with AAEE, DG, DR

10 Lesser Challenges Load will disappear Demand is still relatively high at 7, 8pm when the sun sets. Bakersfield Forecast, Reverse Power Flow Can be evaluated with normal planning tools Distribution Protection will need to be revised A lot of DG at the end of a line may cause thermal overloads for the smaller conductor.

11 Non Powerflow Challenges (?) Rate Structures Time of use pricing may alter behavior This will challenge existing assumptions and how we do or should analyze our system to ensure future reliability Peak hour may be less reliable than in the past as the energy landscape becomes more active and dynamic (as opposed to passive and static or routine) Over generation of power mid day (Duck Curve) More of a market concern. Where do those MW go? Storage may also shift or change behavior (as seen by the transmission system)

12 Voltage Rise with Light loads

13 Stability and Inertia Asynchronous units (inverter based) behave differently than typical rotating machines. No energy stored in a spinning mass (inertia) Little to no response during faults and dynamic events Can inverters provide an inertia like response? Research results to be published soon! Will this reduce reliability for the grid? The key is at what level, and can we offset the change in characteristics

14 Frequency Response with Increased Renewables Source:

15 Frequency Response with Increased Renewables, Modeling Assumptions "Adjusted" "Normal" DG starts all DG DG starts all DG to trip trips to trip trips Voltage Frequency How will we handle the challenge of different vintage of controls mixed together in the DER?

16 Key Takeaways DERs have benefits, but also add new challenges to utility planning How can we as an industry find new solutions to these new and emerging challenges? Increasingly complex forecasts Need to account for timing and load shapes, peak load is not sufficient Increasing complexity of models May need to disaggregate portions of the load model for better accuracy and transparency, Netting of loads may be problematic Higher voltages Will likely cause issues Traditional or new solutions may be needed Decreased inertia and frequency response Not yet evident that this is a problem Add traditional machines, synthetic inertia or TBD? Assumptions need to be checked, they are not fixed and are rapidly becoming outdated!

17 Questions? Answers?

18 Thank You Jameson Thornton, Senior Grid Innovation Engineer 18 - INTERNAL