Boosting Wind and Solar Energy: Opportunities and ...dryer Vacuum Microwave Oven Clothes dryer Air conditioner ~ 1000 W ~ 1 W ~ 10 W ~ 100 W Electric vehicle charging ~ 1 kW to 100

Lucy Pao April 2019

Boosting Wind and Solar Energy: Opportunities

and Technological Challenges

Lucy Pao

Palmer Endowed Chair ProfessorElectrical, Computer, & Energy Engineering

Lucy Pao April 2019

Boosting Wind and Solar Energy: Opportunities

and Technological Challenges

Lucy Pao

Palmer Endowed Chair ProfessorElectrical, Computer, & Energy Engineering

Lucy Pao April 2019

How much power do you use?

[ images from overstock.com, pcworld.com, apple.com, tesla.com ]

Laptop Mobilephone

TV

Dishwasher

( 103 W = 1 kW )Area

heater

Coffee machine

Toaster

Electric kettle

Iron

Hair blow dryer

Vacuum

Microwave

Oven

Clothes dryer

Air conditioner

~ 1000 W~ 1 W ~ 10 W

~ 100 W

Electric vehicle charging~ 1 kW to 100 kW

106 W = 1 MW

109 W = 1 GW

~ Small Town

~ City

2

Lucy Pao April 2019

Units of Power and Energy

Dishwasher

( 103 W = 1 kW )Area

heater

Coffee machine

Toaster

Electric kettle

Iron

Hair blow dryer

Vacuum

Microwave

Oven

Clothes dryer

Air conditioner

~ 1000 W

Energy1 kWh = 1 kW for 1 hour

Electric vehicle charging~ 1 kW to 100 kW

[ images from overstock.com, pcworld.com, apple.com, tesla.com ]

106 W = 1 MW

109 W = 1 GW

~ Small Town

~ City

3

Lucy Pao April 2019

Renewable Energy & The Power Grid

[ images from constructionreviewonline.com, proprofs.com, gapenergysolutions.com, resilience.org ]

Hydro

Wind

Solar PV

Grid Integration

3

Lucy Pao April 2019

How does hydropower work?

[ image from Hydropower 101 on yourtube.com ]4

Lucy Pao April 2019

How much hydropower is there?� End-of-2017

global installed hydropower capacity was 1,267 GW; expected to increase3% annually over next 25 years

� EU has 293 GW

� Austria has 14 GW

[ end-of-2017 data from hydropower.org ]5

China27%

US8%

Brazil8%

Canada6%

Japan4%India

4%Russia

4%Norway

3%

Turkey2%

France2%

Other32%

Lucy Pao April 2019

[ image from Hydropower 101 on yourtube.com ]

Hydropower Advantage: if there is sufficient water Æ can control the amount of power generated

in similar way as with coal or natural gas

4

Lucy Pao April 2019



Hydro

Wind

Solar PV

Grid Integration

6

Lucy Pao April 2019

How does wind power work?

[ figure from www.energyland.emsd.gov.hk

based upon originalfrom US Dept. of Energy ]

Tower Generator

� Goal is to maximize power generation

7

Lucy Pao April 2019[data from gwec.net, navigant.com, and 2017 Wind Technologies Market Report (LBNL)]

� End-of-2017global installed wind capacity was 539 GW; average annual growth of 16% over last decade

� EU has 169 GW; average annual growth of 10%

� Austria has 2.8 GW; average annual growth of 11%

How much wind power is there?

China36%

US17%Germany

9%

India6%

Spain4%

UK3%

France3%

Canada2%

Brazil2%

Italy2%

Other16%

8

Hydro: World: 1267 GWEU: 293 GWAustria: 14 GW

Lucy Pao April 2019



Hydro

Wind

Solar PV

Grid Integration

10

Lucy Pao April 2019

How does solar PV work?

� PV panel consists of layers of material that produce electricity when light shines on it

� Lower-end PV solar cells now achieve about 14-17% efficiency

� Higher-end solar cells can achieve about 20-30% efficiency

� Research laboratories have demonstrated > 40%

� Goal is to maximize power generation [ en.wikipedia.org/wiki/Solar_cell ]

11

Lucy Pao April 2019

� End-of-2017 global installed solar PV capacity was 403 GW; average annual growth of 38% over last decade

� EU has 107 GW; average annual growth of 26%

� Austria has 1.25 GW; average annual growth of 44%

How much solar PV power is there?

[ Data from iea-pvps.org ]12

China32%

US13%

Japan12%

Germany10%

Italy5%

India5%

UK3%

France2%

Australia2%

Other16%

Wind: World: 593 GWEU: 169 GWAustria: 2.8 GW

Lucy Pao April 2019

Growth of Hydro, Wind, and Solar PV

12

Year

Glo

bal I

nsta

lled

Cap

acity

(GW

)

Lucy Pao April 2019

Wind and Solar PV Penetration

[ Source: 2017 Wind Technologies Market Report, Lawrence Berkeley National Lab ]

Approximate Wind Penetration, end of 2017

[ 2017 solar data from iea-pvps.org ]

Approximate Solar PV Penetration, end of 2017

14

Lucy Pao April 2019



Hydro

Wind

Solar PV

Grid Integration

15

Lucy Pao April 2019

Power Systems

When power demanded and power generated are approximately equal, synchronous generators on a network tend to stabilize each other.

Large mismatches between demanded and generated power causes destabilization of the grid.

[Based upon a slide from Mark Ahlstrom of WindLogics]

Most traditional power plants have synchronous generators.

16

Lucy Pao April 2019

Generation Load

Grid Frequency Fluctuations

fgrid = 50 Hz fgrid < 50 Hz fgrid > 50 Hz

[Slide courtesy of Jacob Aho]

17

Lucy Pao April 2019

Generation Load

Frequency Drops if Electrical Power Generated < Electrical Load


Equivalent PowerGeneration


17

Lucy Pao April 2019

Generation Load


Equivalent PowerGeneration


Frequency Rises if Electrical Power Generated > Electrical Load

17

Lucy Pao April 2019

Balancing Electrical Generation and Load

�Traditionally, generation is controlled to match varying load� Operational reserves needed� Imbalance causes frequency variations on utility grid

Generation

coal nuclear hydrogas

Load

appliances,lighting, gadgets,cooling, heating, etc.

18

Lucy Pao April 2019

Balancing Electrical Generation and Load

Large frequency fluctuations can cause load shedding, or even blackouts

�Traditionally, generation is controlled to match varying load� Operational reserves needed� Imbalance causes frequency variations on utility grid

18

Lucy Pao April 2019

Changes due to Wind and Solar PV

� Wind turbines and solar PV arrays are typically decoupled from the grid through their power electronics� In the past, wind and solar generally have not participated

in “balancing services”� Creates increased burden on remaining generating units

Generation

coal nuclear hydrogas

windsolar

Load

appliances,lighting, gadgets,cooling, heating, battery charging, etc.

etc.

19

Lucy Pao April 2019

How does wind power work?

[ figure from www.energyland.emsd.gov.hk

based upon originalfrom US Dept. of Energy ]

Tower

Gear box

High-speed shaft

Generator

Low-speed shaft � Goal is to maximize power generation

7

Lucy Pao April 2019

How does solar PV work?

� PV panel consists of layers of material that produce electricity when light shines on it

� Lower-end PV solar cells now achieve about 11-15% efficiency

� Higher-end solar cells can achieve about 20-30% efficiency

� Research laboratories have demonstrated > 40%

� Goal is to maximize power generation [ en.wikipedia.org/wiki/Solar_cell ]

11

Lucy Pao April 2019

Possible Solution: APC of Wind and Solar

� Active Power Control of Wind and Solar PV Power Plants

� De-rate wind and solar power plants

� Enable wind turbines and solar photovoltaic panels to follow changing power reference commands

[figure from a presentation by A. Kowli, original from SVK (Swedish national grid)]

20

Lucy Pao April 2019

Wind Turbine Field Test Results[ 2013 – 2015, Aho, Buckspan, Fleming, Pao ]

Rated Power

IdealField Test Input

-0.15

-0.1

-0.05

0

Freq

Dev

iatio

n[H

z]

500510520530540550

Pow

er [k

W]

0 50 100 150 200Time [s]

Commanded PowerGenerated Power

21

Lucy Pao April 2019

Solar PV Array Field Test Results[ 2016 – 2017, Hoke, Shirazi, Chakraborty, Muljadi, Maksimovic ]

7 7.5 8 8.5 9Time [s]

-1

-0.5

0

Freq

Dev

[Hz]

1

2

3

Pow

er [k

W]

ActualIdeal

Estimate of Possible PowerCommanded PowerGenerated Power

22

Lucy Pao April 2019

Other Possible Solutions

� Curtail wind and solar as needed

� More transmission lines

� Improved wind and solar forecasts

� Demand-side management� Thermal storage� Time-of-use pricing and “optimal”

pricing strategies

[figure from a presentation by A. Kowli, original from SVK (Swedish national grid)]

� Storage (at GWh scale)� Expensive� Effect of millions of electric

vehicles, whose batteries can be either a load or a supply

23

Lucy Pao April 2019

Pumped Hydro as a Means of Storage

[ image from antinuclear.net ]24

Lucy Pao April 2019

Summary

While there are many challenges, there are many solution possibilities.

25

Lucy Pao April 2019

Acknowledgments

Research supported by:

as well as other industry (who wish to remain

anonymous)

26

Lucy Pao April 2019

April 2018

Current students, recent postdoc: Daughter:

Michael Sinner

Lucy Pao

R. Arnold Braker

Christopher Bay(2017-2018)

Daniel Zalkind

NikharAbbas

DavidPasleyjoined

in August2018

Acknowledgments

27

Sarah Pao

Radzihovsky

Lucy Pao April 2019

Vielen Dank!

Boosting Wind and Solar Energy: Opportunities and ...dryer Vacuum Microwave Oven Clothes dryer Air conditioner ~ 1000 W ~ 1 W ~ 10 W ~ 100 W Electric vehicle charging ~ 1 kW to 100

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