Inexpensive Ancillary Service from

Automated Load Tuning

Prabir Barooah

Mechanical and Aerospace Engineering,University of Florida

in collaboration with Prof. Sean Meyn, He Hao, Yashen Lin,

Tim Middelkoop, and PPD@UF

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Operating  the  grid  is  a  control  problem,..

00 01 02 03 04

5

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15

Day-ahead forecastHourly schedule

Time (h)

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wer

(G

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ResidualLoad following

Hour ahead forecastTotal dispatch

Time (h)

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Regulation

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(non-­‐contingency)  balancing  currently  achieved  by

>  feedforward  :  scheduling  and  dispatching  generation  to  match  predicted  load>  feedback  :    “frequency  regulation”

slow,  large  generators:  energy  small,  fast  ramping  generators:  ancillary  services

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

..,  it  needs  actuators  to  provide  energy  and  ancillary  services    

Power Grid

Actuation

Control

Water Pump

Batteries

HVAC

Coal

Gas Turbine

BP

BP

BP

BP

BP

Measurements: Voltage Frequency Phase

HC!

!

 Nuclear      

 gas  turbines      

slow,  large  generators:  enginesmall,  fast  ramping  generators:  flaps

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

The  trouble(?)  with  solar  and  windPotential  for  tremendous  societal  benefit  :  33%  energy  from  solar  and  wind  will  reduce  carbon  emissions  by  ~30%,  and  save  ~7  billion  $  per  year  (NREL  western  wind  and  solar  integration  study,  phase  2,  Sept.  2013)

Potential  for  headache:  (Germany,  U.S.  Pacific  Northwest,...)not  controllable,  (i)  Volatile  (time  varying),    (ii)  Unpredictable

Regulation  requirement Load-­‐following  requirement

Hellman,  Resources  and  transmission  planning  to  achieve  a  33%  RPS  in  CAISO....  ,  2010

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

*1980:  Schweppe  et  al.

Automated  Load  Tuning  to  obtain  Inexpensive  Ancillary  Services

1.  Flexible  loads              short-­‐term  storage2.  Load  Tuning                Demand  Response3.  FERC  755  

6==

build  more  gas  turbines?giant  batteries?

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

✦ Now:  dispatchable  generation  meeting  demand

✦ Future:  tune  demand  to  meet  volatile  generation*

✦ Enabling  resource:  flexible  loads  

✦ Task:  tune  loads  to  provide  ancillary  service,  without  causing  inconvenience  to  consumers  the  loads  serve

✦ has  to  be  inexpensive  to  the  grid  as  well  as  to  the  consumer

✦ has  to  respect  capacity  and  bandwidth  (time-­‐scale)  constraints  of  loads

*1980:  Schweppe  et  al.

Automated  Load  Tuning  to  obtain  Inexpensive  Ancillary  Services

1.  Flexible  loads              short-­‐term  storage2.  Load  Tuning                Demand  Response3.  FERC  755  

6==

build  more  gas  turbines?giant  batteries?

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

option  1:  Hierarchical  control  architecture

CG

C

CC

grid  operator

Grid

option  2:  fully  distributed    (not  in  this  talk)

Automated  Load  Tuning

Intelligence  at  the  nodes

“high  bandwidth”  

loads

“medium  bandwidth”  

loads

“low  bandwidth”  

loads

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

#1  Source  of  flexible  loads:  buildings

www.eia.gov

•HVAC  systems  in  commercial  buildings:  approx  20%  of  national  electricity  consumption  (U.S.)•Large  thermal  inertia,  so  small  and  fast  variation  in  air  flow  has  little  effect  on  indoor  climate•Buildings  with  VAV  (variable  air  volume)  systems  are  particularly  well  suited  for  load  tuning

Next:  ancillary  service  from  “variable  speed”  loads  in  commercial  buildings

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

chiller

 VAV  (Variable  air  volume)  HVAC  systems

Electricity  consumers  in  order:1.  chiller2.  fans

3.  pumps(4/2/1)  heating  

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

FanController

Regulation

Desired air !ow Air !ow

Controller

Fan

Building

+

ur

pb+r

v

rRegulation Signal

fan  speed

+  climate  controller

fan  speedcommand

building  control  system  

Case  study  #1:    obtain  “high  frequency”  ancillary  service,  in  [1/(5  min)          1/(8  sec)]

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Case  study  #1:    obtain  “high  frequency”  ancillary  service,  in  [1/(5  min)          1/(8  sec)]

Grid  operator

Band  pass  filter  to  ensure  the  climate  control  unit  doesn’t  “fight”  the  regulation  command

FanController

Regulation

Desired air !ow Air !ow

Controller

Fan

Building

+

ur

pb+r

v

rRegulation Signal

fan  speed

+  climate  controller

fan  speedcommand

bandpass  filter

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

10010-3 1/600 1/8

0 Regulation Command to Fan Speed

Frequency (Hz)

Mag

nit

ude

(dB

)-20

-40

-60

Regulation Command to Temperature

FanController

Regulation

Desired air !ow Air !ow

Controller

Fan

Building

+

ur

pb+r

v

rRegulation Signal

fan  power

+  climate  controller

fan  speedcommand

BP  filter

Band  pass  filter  to  prevent  “fight”  between  controllers

power

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Excellent  tracking  with  little  impact...

13 14 15 16 17

−5

0

5

Time (h)

Pow

er (k

W)

Regulation Actual Estimation

13 14 15 16 17−0.1

−0.05

0

0.05

0.1

Time (h)

Tem

pera

ture

(o C)

..  as  long  as  you  maintain  frequency  (time  scale)  separation  

Simulation  results:

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Experimental  results  :  Pugh  Hall  @  UFAHU  2:  serves  auditorium

20 21 22 23 24 25−1.5

−1

−0.5

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0.5

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Time (min)

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er (k

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0 20 40 60 801

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Pow

er (k

w)

Fan power

0 20 40 60 8072

72.5

73

73.5

74

Time (min)

Tem

p (o F)

Room temperature

FanPlant

ub

ur

uaPf

Regulationcontroller

Pref

Reference:  PJM  regD,  bandpass  filtered    [1/(30  s)      1/(120  s)  ]

Ack:  PPD,  TM,  Yashen,  ....

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Experimental  results  :  Pugh  Hall  @  UFAHU  2:  serves  auditorium

20 21 22 23 24 25−1.5

−1

−0.5

0

0.5

1

1.5

2

Time (min)

Pow

er (k

w)

Reference signalMeasured power deviation

0 20 40 60 801

2

3

4

Pow

er (k

w)

Fan power

0 20 40 60 8072

72.5

73

73.5

74

Time (min)

Tem

p (o F)

Room temperature

FanPlant

ub

ur

uaPf

Regulationcontroller

Pref

Reference:  PJM  regD,  bandpass  filtered    [1/(30  s)      1/(120  s)  ]

Ack:  PPD,  TM,  Yashen,  ....

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Experimental  results  :  Pugh  Hall  @  UFAHU  2:  serves  auditorium

20 21 22 23 24 25−1.5

−1

−0.5

0

0.5

1

1.5

2

Time (min)

Pow

er (k

w)

Reference signalMeasured power deviation

0 20 40 60 801

2

3

4

Pow

er (k

w)

Fan power

0 20 40 60 8072

72.5

73

73.5

74

Time (min)

Tem

p (o F)

Room temperature

FanPlant

ub

ur

uaPf

Regulationcontroller

Pref

Reference:  PJM  regD,  bandpass  filtered    [1/(30  s)      1/(120  s)  ]

Ack:  PPD,  TM,  Yashen,  ....

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

35  kW  fan  motor

Resource Ancillary  service  potential

5  kW

46,000  sq.ft  bldg,75  kW  fan  power

11  kW

All  buildings  in  the  U.S.  with  VAV  HVAC  systems

6.6  GW

70%  of  the  regulation  capacity  needed  by  the  US  in  2012,  in  the  high  frequency  range  (  ~1/1  min)

How  much  can  this  help?  A  LOT!

Ref: Ancillary Service for the Grid Via Control of Commercial Building HVAC Systems, He Hao, Anupama Kowli, Yashen Lin, Prabir Barooah, Sean Meyn, American Control Conference, June, 2013

>  Economic  incentive?  FERC  oder  755  (2011)>  Load  aggregation?

Inexpensive!        1.  software  add  on,  no  change  in  equipment

2.  non  disruptive  to  consumer  service  

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

ufan

m

Tla

Pchiller

[τ1 τ2]

Case  study  #2:    obtain  “medium  frequency”  ancillary  service,  in  [1/(60  min)          1/(5  min)]

Medium  frequency  variation  in  air  flow  will  affect  (i)  fan  power  and  (ii)  chiller  power  consumption  

Good  :  much  more  ancillary  service!

Bad  :  delay,  more  complex  dynamics,  lack  of  direct  actuation  ability  

! d "

small

ufan

m

Tla

Pchiller

high  freq.  variation  in  air  flow  rate low    freq.  variation  in  air  flow  rate

chiller air  flow  ratepower

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

0 5 10 15 20−40−20

02040

Pow

er (K

W)

Real Reference

0 5 10 15 2070

75

80

T (F

)

RealBaseline

0 5 10 15 2002468

Time (h)

ma

(kg/

s)

RealBaseline

Regulation Controller Closed-loop Building Dynamics

Band-pass Filter+ Scaling Indoor Climate

Controller

KalmanPredictor

SmithPredictor

ZoneDynamics

Fan/Duct/DamperDynamics

PowerModel

maz

madmar ma

P̃r

Pb

Pd P

P

T

dp

Tmix Wmix

Indirect  actuation  of  chillers  without  VFDs  

To  handle  transport  delay  in  chiller:  1.  Predict  reference  command  (Kalman  filter),  2.  delay  tolerant  controller

Approx  80  GW  of  ancillary  service  in  the  medium  frequency  [1/(60  min)        -­‐      1/(5  min)]  range,

with  about  1oF  temperature  deviation

Ref: Low Frequency Ancillary Services from Commercial Building HVAC Systems, Yashen Lin, Prabir Barooah, Sean Meyn, IEEE Smart Grid Comm, October, 2013, Vancouver, Canada

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Ancillary  service  from  on/off  loads?Residential  flexible  loads  (A/Cs,  refrigerators,..)

Commercial  flexible  load  (constant  volume  HVAC,  on/off  chillers,  pool  pumps*)

Constraint:  capacity  and  bandwidth  of  loads  (time  scale  of  flexibility)

*FP&L:  780,000  customers  enrolled  in  On-­‐Call

Existing  work  :  thermostatic  loads  (Hiskens,  Callaway,  Mathieu,....)

Case  study  #3:    “low  frequency”  ancillary  service,  in  [1/(a  few  hours)          1/(1  hour)]

using  on/off  resources  :  pool  pumps*  (1  GW  load  in  FL)

Intelligence  at  the  node:>  randomized  policy,  “control”  changes  the  transition  probabilities  p(on  |  has  been  off  for  i  hours)>  optimal  control  :  minimize  -­‐zU(x)  +  D(p  ||    p_0)(needs  of  the  grid  +  needs  of  the  consumer)>  closed  form  solution:  family  of  trans.  probs.  parameterized  by  z

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Ancillary service to the grid from deferrable loads: the case for intelligent pool pumps in Florida, Sean Meyn, Prabir Barooah, Ana Busic and Jordan Ehren, IEEE Con. on Decision and Control, Dec 2013, Florence, Italy.

r(t)  :    BPA  regulation  signal

Intelligence  at  the  grid:>  task:  design  z  so  that  power  consumption  dev.  of  a  collection  of  pool  pumps  tracks  a  reference  signal  r(t)>  mean  field  limit  of  a  collection  of  pool  pumps:  min.  phase  LTI  system

simulation  with  1  million  “Markovian”  pools,  1  kW  each

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Power Grid

Actuation

Control

Water Pump

Batteries

HVAC

Coal

Gas Turbine

BP

BP

BP

BP

BP

Baseline Generation

Disturbancesfrom nature

Measurements: Voltage Frequency Phase

HC!

!

Flexible  loads  providing  ancillary  service

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Power Grid

Actuation

Control

Water Pump

Batteries

HVAC

Coal

Gas Turbine

BP

BP

BP

BP

BP

Baseline Generation

Disturbancesfrom nature

Measurements: Voltage Frequency Phase

HC!

!

Flexible  loads  providing  ancillary  service

Power GridControl

Water Pump

Batteries

LOAD

Coal

Gas Turbine

BP

BP

BP C

BP

BP

Measurements: Voltage Frequency Phase

HC!

!

Actuator feedback loop

A

Intelligence  at  the  nodes:  control  of  the  actuators  

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

option  1:  Hierarchical  control  architecture

CG

C

CC

grid  operator

Grid

option  2:  fully  distributed  ?

Automated  Load  Tuning:  recapIntelligence  at  the  nodes,  

respecting  capacity  and  bandwidth  constraints

flywheel,  batteries

HVAC,  heaters,  EVsflexible  manufacturing

Economic  incentive:  FERC  oder  755  (2011)

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

Looking  into  the  crystal  ball  (personal  opinion)

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

✦ When  the  distinction  between  Generation  and  Loads  diminish  (as  providers  of  ancillary  service),  the  current  language  is  less-­‐than-­‐desirable:  

✴ “load  following”

✴ “Capacity  constraint”,  “ramp  rate  constraint”,  “energy  constraint”,  “regulation  reserve”,  “gain”

✦ Challenges  in  ......  ,  actuation,  ...  for  future  power  systems  (?)

Looking  into  the  crystal  ball  (personal  opinion)

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

✦ When  the  distinction  between  Generation  and  Loads  diminish  (as  providers  of  ancillary  service),  the  current  language  is  less-­‐than-­‐desirable:  

✴ “load  following”

✴ “Capacity  constraint”,  “ramp  rate  constraint”,  “energy  constraint”,  “regulation  reserve”,  “gain”

✦ Challenges  in  ......  ,  actuation,  ...  for  future  power  systems  (?)

Looking  into  the  crystal  ball  (personal  opinion)

|G(j!)|

\G(j!)

!(= 1/⌧)1.  bandwidth

2.  PSD

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

✦ When  the  distinction  between  Generation  and  Loads  diminish  (as  providers  of  ancillary  service),  the  current  language  is  less-­‐than-­‐desirable:  

✴ “load  following”

✴ “Capacity  constraint”,  “ramp  rate  constraint”,  “energy  constraint”,  “regulation  reserve”,  “gain”

✦ Challenges  in  ......  ,  actuation,  ...  for  future  power  systems  (?)

Looking  into  the  crystal  ball  (personal  opinion)

|G(j!)|

\G(j!)

!(= 1/⌧)1.  bandwidth

2.  PSD

✦ Unintended  consequences  due  to  focus  on  energy  efficiency    

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

National  Science  Foundation,  DOE(EPAS,  CPS)

Financial  support  from

Parting  Comments

‣A  sustainable  energy  future  with  a  high  renewable  energy  portfolio  requires  substantially  large  amounts  of  inexpensive  ancillary  service

‣Tuning  of  a  large  number  of  loads  offers  a  vast  and  untapped  source  of  inexpensive  ancillary  service

‣In  principle,  can  be  solved  through  appropriate  automation

Many,  many,  many  open  research  questions:1.  technological

2.  social-­‐science  related2.  economic

.....Future of Power Workshop @ NSF, Washington DC, Nov 16, 2013

References

1. How demand response from commercial buildings will provide the regulation needs of the grid, He Hao, Timothy Middelkoop, Prabir Barooah and Sean Meyn, invited paper, 50th Allerton Conf., Oct. 2012. 2. Ancillary Service for the Grid Via Control of Commercial Building HVAC Systems, He Hao, Anupama Kowli, Yashen Lin, Prabir Barooah, Sean Meyn, American Control Conference, June, 20133. Ancillary Service to the Grid through Control of Fans in Commercial Building HVAC Systems, He Hao, Anupama Kowli, Yashen Lin, Prabir Barooah, Sean Meyn, IEEE Transactions on Smart Grid, under review4. Low Frequency Ancillary Services from Commercial Building HVAC Systems, Yashen Lin, Prabir Barooah, Sean Meyn, IEEE Smart Grid Comm, October, 2013, Vancouver, Canada5. Ancillary service to the grid from deferrable loads: the case for intelligent pool pumps in Florida, Sean Meyn, Prabir Barooah, Ana Busic and Jordan Ehren, IEEE Con. on Decision and Control, Dec 2013, Florence, Italy.

National  Science  Foundation,  DOE(EPAS,  CPS)

Acknowledgements:

Classifieds:

1. Workshop at the IEE CDC on “Ancillary Service from Flexible Loads to Help the Electric Grid of the Future” by Barooah, Hiskens, Kowli, Meyn, Mathieu, December 9, Florence, Italy

2. 2nd Interdisciplinary workshop on Smart Grid design and implementation, Gainesville, FL, March 28-29, 2014: http://ccc.centers.ufl.edu/?q=SG2014 (ECE and College of Business Administration)

http://humdoi.mae.ufl.edu/~pbarooah/Research/PBresearch_buildings.html