Thomas Key, EPRI Senior Technical Executive

© 2015 Electric Power Research Institute, Inc. All rights reserved.

Thomas Key, EPRI

Senior Technical Executive

ISES Webinar

April 22, 2016

An Integrated Grid

Path for Solar

2


Changing Landscape: An Integrated Grid is a Better Grid

Combined Heat & Power

Demand Response

Energy

Management

Rooftop Solar

Electric

Vehicles

Energy Storage

Two Way

Power

3


From EIA Database

US, March 2016 Electricity Report

History of U.S. Net Generation (billion kWh)

4


Noting History… PV Module Price Trajectory

$100

$1,000

$10,000

$100,000

0.00 0.01 0.10 1.00 10.00 100.00 1000.00

PV

Mo

du

le P

rice

Cumulative Sales, GWP

Source: SPV Market Strategies (adapted by EPRI)

This illustrates how the historical average module selling price has declined by

about 20% with each doubling of sales over several decades..

5


Noting History… Cell Efficiency Trajectory

Efficiency Data Points from NREL

6


Solar PV, a key driver of change

DOE “SunShot” Vision Study,

Released February 2012

Is the grid ready for PV?

US Future?

302 GW PV

by 2030

Germany Now – Power Demand

for one week in May 2015

60 GW

Export Import

7


US Solar compared to Germany Solar

Germany: >40 GW

U.S.: >25 GW in 2016

(Solar Resource Availability: NREL, PV Capacity Additions: SEPA)

Fastest growing generation technology, ~200 GW worldwide

U.S. total capacity ~25 GW at beginning of 2016

8


Solar PV Radiation at Latitude Tilt

Germany 2015 >40 GW, ~ 3.2 kWh/m2/day

U.S. 15 >20 GW, ~ 5 kWh/m2/day

(Solar Resource Availability: NREL, PV Capacity Additions: SEPA, total solar radiation latitude tilt)

Fastest growing of all renewable technologies

~180 GW installed worldwide, Germany leads with ~38 GW


Solar PV the poster child of grid edge assets

Germany 2015 >40 GW, ~ 3.2 kWh/m2/day

U.S. 2015 >20 GW, ~ 5 kWh/m2/day

(Solar Resource Availability: NREL, PV Capacity Additions: SEPA, total solar radiation latitude tilt)

Fastest growing of all renewable technologies

~180 GW installed worldwide, Germany leads with ~38 GW


9


Solar Potential by country assuming residential PV Costs

Source: Bloomberg New Energy Finance

2014 2025

Solar Powered Song.pptx

Solar Powered Song.pptx

10


Interconnection Challenge: Solar output variability Calendar based on irradiance, 1-min averages at 30° fixed tilt, Knoxville

1 2 3 4 5

6 7 8 9 10 11 12

13 14 15 16 17 18 19

20 21 22 23 24 25 26

27 28 29 30

Tue Wed Thu Fri SatSun Mon

April 2014

11


Single-Module Ramp Events on 1-MW Site in TNMeasured 1-sec output from a 224-W module with micro-inverter

(Sep 29, 2011)... 13:10 13:11 13:12 13:13 13:140

0.05

0.1

0.15

0.2

0.25

X: 29-Sep-2011 13:10:23

Y: 0.03976

AC

Po

wer

(kW

)

Single-Module PV System Power Production Profile

Local Date & Time (Eastern)

X: 29-Sep-2011 13:10:09

Y: 0.2183

X: 29-Sep-2011 13:11:31

Y: 0.03838

X: 29-Sep-2011 13:11:40

Y: 0.2219

–0.18kW in 24 sec

(3.3% per sec)

+0.18kW in 9 sec

(9.1% per sec)

12


PV variable output on distribution feeder Circuit map showing locations of pole-mount systems in Rome, GA

SubstationSubstation

© Google – Map data © Google

= DPV Site= DPV Site

0.0 mi.0.0 mi. 0.5 mi.0.5 mi. 1.0 mi.1.0 mi.

1 km2 grid

MagicCarpet4 Rome May 2.wmv

MagicCarpet4 Rome May 2.wmv

13


Spatial- and time-based PV-feeder demo

Search: “Youtube Epri Pv Penetration”

EPRIMagicCarpetYouTube.mp4

EPRIMagicCarpetYouTube.mp4

14


Potential Grid Issues with PV Variability

Voltage Control

• Overvoltage

• Voltage variations

Equipment Operation

• Feeder regulators,

• Load tap changers

• Switched capacitor banks

Demand/Energy

• “Masking” peak demand

• Unbalancing supply and demand

System Protection

• Relay desensitization, networks

• Breaker reduction of reach

• Unintentional islanding

Power Quality

• Harmonic generation

• Flicker worries

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

7 8 9 10 11 12 13 14 15 16 17 18 19

Po

wer (p

er-

unit)

Hour

15


Example: Overvoltage related hosting capacity

2500 cases shown

Each point = highest primary voltage

ANSI voltage limit

Ma

xim

um

Fe

ed

er

Vo

lta

ge

s (

pu)

Increasing penetration (kW)

Minimum Hosting CapacityMaximum Hosting Capacity

Total PV:

540 kW

Total PV:

1173 kW

Voltage violation

No observable violations regardless of

size/location

Possible violations based upon size/location

Observable violations occur regardless of

size/location

16


Individual feeder PV “Hosting Capacity” is important

Baseline – No PV

PV Penetration 1

PV Penetration 2

PV Penetration 3

Beyond…

Increase

Penetration Levels

Until Violations

Occur

• voltage

• protection

• power quality

• thermal

PV

SystemsProcess is

repeated

100’s of

times to

capture

many

possible

scenarios

17


Substation Marker

*hosting capacity

*Initial analysis results from TVA/EPB study, results not

finalized

Mapping Feeder Hosting Sample Chattanooga, TN, USA

System Hosting Capacity(~ 300 distribution feeders)

Substation-level

Hosting Capacity

Feeder-level

Hosting Capacity

18


Inverter – Role in PV Plants

PV inverter converts DC energy from solar modules in to AC energy and

interface the PV system with electricity grid

DC Power AC Power

Traditional Inverter

Functionality

Smart Inverter Functionality

• Matching PV output with grid

voltage and frequency

• Providing safety by providing

unintentional islanding

protection

• Disconnect from grid based on

over/under voltage/frequency

• Voltage Support

• Frequency Support

• Fault Ride Through (FRT)

• Communication with grid

19


Planning with DER - Mitigation

Primary Voltage

0.9

0.925

0.95

0.975

1

1.025

1.05

0 4 8 12 16 20

Hour

Volta

ge

(p

u)

Baseline – No PV

20% PV20% PV with

smart inverter

24 Hour Simulation

• Often least-cost solution

• Increased hosting capacity

Improved

Integration with

Smart Inverters

Analytics

• Screening

• Hosting Capacity

• Reliability

• DER/Grid Modeling

Tools

• Advancing commercial tools

• Open-source (OpenDSS)

Mitigation

• Smart inverters

• Grid-side enhancements

Training

• Engineering Guidelines

• Planning with DG

20


Advanced Inverters Have Significant Upside

ANSI voltage limit

ANSI voltage limit

EPRI White Paper summarizing ~ 5

years of research on the Integration

of DER.

Search “EPRI and 3002004777”

21


Conclusions: Key Takeaways

Variable PV works better with the grid

We need to leverage our existing grid,

cultivate “hosting capacity”

Grid upgrades and reinforcements

increase hosting, see PVGrid

Future DG to provide grid support

with Smart Inverters

An integrated grid approach will help

to transform the power system

Transforming the Power System will be a Journey not a Destination

IntegratedThe Whole is Greater

than the Sum of its

Parts

22


Questions?

Tom Key, [email protected]

www.epri.com

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Thomas Key, EPRI Senior Technical Executive

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