Renewable Energy Futures in the East - Solar Integration...

Renewable Energy Futures in the East

Josh Novacheck and Greg Brinkman

SIW17-135

January 1, 2017

NATIONAL RENEWABLE ENERGY LABORATORY 2

Background

Renewable Energy Futures Study investigated large transformation of the U.S. Power System


Eastern Renewable Generation Integration Study


• Nuclear plants retired • No hurdle rates between

regions in Base scenario • ERGIS Sub-Regions define flow

limits • VG can provide reserves • ERGIS reserve methodology

REFutures in the East: Base Scenario

Onshore Wind (%)

Offshore Wind (%)

Solar PV (%)

Hydro (%)

Total wind + solar + hydro

FRCC 0% 0% 30% 0% 30% ISO-NE 33% 10% 20% 6% 69% MISO 76% 0% 20% 2% 98% NYISO 44% 5% 20% 16% 84% PJM 11% 27% 25% 1% 64% SERC 0% 3% 25% 3% 32% SPP 144% 0% 20% 1% 165%

Total 37% 9% 26% 3% 75%


Scenarios

Base High VG Hurdle Rate Inflexible Baseload

Local Conventional

ERGIS Thermal

and Hydro Assumptions

ERGIS ITx30 Transmission

70% VG Nuclear units

retired Baseload units

(all ERGIS coal units) have coal flexibility

Increase VG by

10% in all regions

Include

$10/MWh charge on imports

~25% of all

Baseload capacity in each region given ERGIS Nuclear flexibility

Always committed at full load when not on an outage

25% of all

regional load must be served by local thermal or hydro resources


REFutures East Implementation – Geographic Decomposition

1. Transmission Flow Forecast

2. Decomposed Unit Commitment

3. Real Time

Model Phase Centralized UC Geographic Decomposition UC

Simplified Day-Ahead

- 10 hours

Day-Ahead 50 hours 1-5 hours/region run in parallel

Real-Time 10 hours 10 hours

Total 60 hours 25 hours

Summary Results


U.S. Eastern Interconnection Generation Annual Results

Scenario VG curtailment

Base 7.3%

High VG 10.2%

Inflexible Baseload

11.4%

Local Conventional

13.7%

Hurdle Rate 8.8%


MISO and SPP large net exporters • Hurdle Rate limits exports to some

degree SERC meets approximately a third of their load through imports

Annual Regional Generation


% Difference from Base Scenario

High VG -7%

Inflexible Baseload 4%

Local Conventional 7%

Hurdle Rate 4%

U.S. Eastern Interconnection Annual Costs

Less flexible scenarios reduce on/off cycling costs, but not enough to reduce benefit from displaced fuel and O&M costs.

System Stress

12

System Stress

• Economic Stress – VG Curtailment

• Operational Stress – Thermal

Headroom – Non-

Synchronous Penetration

– CT Starts and Usage


• Curtailment is modest or non-existent for more than half the year

• Hurdle Rate leads to nearly identical “extreme” curtailment as Base

VG Curtailment


• Low curtailment in Summer months suggest value of seasonal energy storage

• High curtailment during peak PV production and low curtailment overnight/evening suggests value daily storage

VG Curtailment


VG Curtailment

Scenario % of Curtailment That Was Scheduled in Day-Ahead

Base 59%

High VG 63%

Inflexible Baseload

59%

Local Conventional

70%

Hurdle Rate 57%


• Headroom considers ability to deal with an increase in net-load

• Undispatched online thermal capacity or curtailed VG can provide headroom

• Scenarios with less flexible operation of thermal fleet do not protect system against low headroom conditions

Headroom


• Total VG generation (post curtailment) relative to the online conventional capacity and VG generation

• Less flexible thermal fleet limits does limit periods of low inertia

• Less coordination between regions leads to higher Non-synchronous penetration in high wind areas

Non-Synchronous Penetration


Quick Start Combustion Turbine Usage


Scheduled Quick Start

Day-Ahead did not well predict the need for quick start generation capacity

Conclusions


• Balancing 70-75% renewables (67% - 72% wind and solar) at 5-min levels in the Eastern Interconnection is possible.

• There was no unserved energy and more than 99.98% of required reserves were procured in the annual grid simulation.

• Curtailment was simulated to range between 7.3% and 10.2% if grid operations are flexible.

• Flexibility challenges led to 9-14% curtailment, making achieving 70% renewables challenging.

• Curtailment and generation from wind and solar resources were somewhat well predicted in the day-ahead simulation

• Peaking generation from natural gas combustion turbines was not well predicted by the day-ahead simulation o 5-minute net-load deviated from average hourly net-load, but much of the deviation is

predictable (i.e. sunrise/sunset)

• More research is needed to understand dynamic stability and voltage issues, and whether additional constraints or technologies may be necessary to operate these scenarios reliably.

Conclusions

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NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Renewable Energy Futures in the East - Solar Integration...

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