Virtual Energy Storage through Distributed Control of Flexible Loads - - PowerPoint PPT Presentation
Virtual Energy Storage through Distributed Control of Flexible Loads - - PowerPoint PPT Presentation
Virtual Energy Storage through Distributed Control of Flexible Loads CaFFEET 2015 Innovative Solutions to Integrate Renewable Energy Ana Bu si c Inria and ENS Paris, France Thanks to my colleagues, Prabir Barooah and Sean Meyn, and
March 8th 2014: Impact of wind and solar on net-load at CAISO Ramp limitations cause price-spikes
Price spike due to high net-load ramping need when solar production ramped out Negative prices due to high mid-day solar production
1200 15 2 4 19 17 21 23 27 25 800 1000 600 400 200
- 200
GW GW Toal Load Wind and Solar Load and Net-load Toal Wind Toal Solar Net-load: Toal Load, less Wind and Solar $/MWh 24 hrs 24 hrs Peak ramp Peak Peak ramp Peak
Challenges
Challenges
Some of the Challenges
1 Ducks
MISO, CAISO, and others: seek markets for ramping products
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Challenges
Some of the Challenges
1 Ducks 2 Ramps
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
GW (t) = Wind generation in BPA, Jan 2015
Ramps 2 / 15
Challenges
Some of the Challenges
1 Ducks 2 Ramps 3 Regulation
2 4 6 8 2 4 6 8 0.8
- 0.8
1
- 1
0.8
- 0.8
1
- 1
Sun Mon Tue October 20-25 October 27 - November 1 Hydro Wed Thur Fri Sun Mon Tue Wed Thur Fri
Generation and Laod GW
GW GW
Regulation GW
Thermal Wind Load Generation Regulation
Error Signal in Feedback Loop
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Challenges
Some of the Challenges
1 Ducks 2 Ramps 3 Regulation
One potential solution: Large-scale storage with fast charging/discharging rates
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Challenges
Some of the Challenges
1 Ducks 2 Ramps 3 Regulation
One potential solution: Large-scale storage with fast charging/discharging rates Let’s consider some alternatives
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Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
Gr(t) G1 G2 G
Traditional generation DD: Chillers & Pool Pumps DD: HVAC Fans
3
Gr = G1 + G2 + G3
Virtual Energy Storage
Virtual Energy Storage
Control Architecture
Frequency Decomposition
Power Grid Control
Flywheels Batteries Coal Gas Turbine
BP BP BP
C
BP BP
Voltage Frequency Phase
H C
Σ −
Actuator feedback loop
A
LOAD
Today: PJM decomposes regulation signal based on bandwidth, R = RegA + RegD Proposal: Each class of DR (and other) resources will have its own bandwidth of service, based on QoS constraints and costs.
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Virtual Energy Storage
Frequency Decomposition
Taming the Duck
March 8th 2014: Impact of wind and solar on net-load at CAISO Ramp limitations cause price-spikes
Price spike due to high net-load ramping need when solar production ramped out Negative prices due to high mid-day solar production
1200 15 2 4 19 17 21 23 27 25 800 1000 600 400 200
- 200
GW GW Toal Load Wind and Solar Load and Net-load Toal Wind Toal Solar Net-load: Toal Load, less Wind and Solar $/MWh 24 hrs 24 hrs Peak ramp Peak Peak ramp Peak
ISOs need help: ... ramp capability shortages could result in a single, five-minute dispatch interval or multiple consecutive dispatch intervals during which the price of energy can increase significantly due to scarcity pricing, even if the event does not present a significant reliability risk
http://tinyurl.com/FERC-ER14-2156-000 4 / 15
Virtual Energy Storage
Frequency Decomposition
Taming the Duck
One Day at CAISO 2020 ISO/RTOs are seeking ramping products to address engineering challenges, and to avoid scarcity prices Do we need ramping products?
Net Load Curve
In c r ea s ed ramp
GW
- 5
5 10 15 20 25
12am 12am 3am 6am 9am 12pm 3pm 6pm 9pm
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Virtual Energy Storage
Frequency Decomposition
Taming the Duck
One Day at CAISO 2020
Net Load Curve
T a m i n g t h e D u c k GW
- 5
5 10 15 20 25
12am 12am 3am 6am 9am 12pm 3pm 6pm 9pm
This doesn’t look at all scary! We need resources, but anyone here knows how to track this tame duck
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Virtual Energy Storage
Frequency Decomposition
Taming the Duck
One Day at CAISO 2020
Net Load Curve Low pass Mid pass High pass
The duck is a sum of a smooth energy signal, and two zero-energy services GW
- 5
5 10 15 20 25
12am 12am 3am 6am 9am 12pm 3pm 6pm 9pm
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Virtual Energy Storage
Frequency Decomposition
Regulation
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
GW (t) = Wind generation in BPA, Jan 2015
Ramps
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Virtual Energy Storage
Frequency Decomposition
Regulation
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
G Goal:
W (t) = Wind generation in BPA, Jan 2015 Ramps
GW (t) + Gr(t) ≡ 4GW
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Virtual Energy Storage
Frequency Decomposition
Regulation
Ra
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
G Goal:
W (t) = Wind generation in BPA, Jan 2015 Ramps Ramps Ramps Ramps Ramps
GW (t) + Gr(t) ≡ 4GW
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Virtual Energy Storage
Frequency Decomposition
Regulation
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
Goal: GW (t) + Gr(t) ≡ 4GW
- btained from
generation? Gr(t) Gr(t)
Ramp
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Virtual Energy Storage
Frequency Decomposition
Regulation
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
Gr(t) Gr = G1 + G2 + G3 G1
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Virtual Energy Storage
Frequency Decomposition
Regulation
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
Gr(t) Gr = G1 + G2 + G3 G1 G2
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Virtual Energy Storage
Frequency Decomposition
Regulation
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
Gr(t) Gr = G1 + G2 + G3 G1 G2 G3
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Virtual Energy Storage
Frequency Decomposition
Regulation
Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06
GW
1 2 3 4
Gr(t) Gr = G1 + G2 + G3 G1 G2 G3 Where do we find these resources?
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Local feedback loop Local Control Load i
ζt Y i
t
U i
t
Xi
t
Grid signal Local decision Power deviation
Demand Dispatch Design
Demand Dispatch
Demand Dispatch
Gr Gr = G1 + G2 + G3 G1 G2 G3 ?
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Demand Dispatch
Demand Dispatch
Gr Gr = G1 + G2 + G3 G1 G2 G Traditional generation
3 7 / 15
Demand Dispatch
Demand Dispatch
Gr Gr = G1 + G2 + G3 G1 G2 G Traditional generation Water pumping (e.g. pool pumps) Fans in commercial HVAC
3
Demand Dispatch: Power consumption from loads varies automatically and continuously to provide service to the grid, without impacting QoS to the consumer
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Demand Dispatch
Demand Dispatch
Responsive Regulation and desired QoS – A partial list of the needs of the grid operator, and the consumer
High quality AS? (Ancillary Service) Does the deviation in power consumption accurately track the desired deviation target?
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Demand Dispatch
Demand Dispatch
Responsive Regulation and desired QoS – A partial list of the needs of the grid operator, and the consumer
High quality AS? (Ancillary Service) Reliable? Will AS be available each day? It may vary with time, but capacity must be predictable.
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Demand Dispatch
Demand Dispatch
Responsive Regulation and desired QoS – A partial list of the needs of the grid operator, and the consumer
High quality AS? Reliable? Cost effective? This includes installation cost, communication cost, maintenance, and environmental.
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Demand Dispatch
Demand Dispatch
Responsive Regulation and desired QoS – A partial list of the needs of the grid operator, and the consumer
High quality AS? Reliable? Cost effective? Customer QoS constraints satisfied? The pool must be clean, fresh fish stays cold, building climate is subject to strict bounds, farm irrigation is subject to strict constraints, data centers require sufficient power to perform their tasks.
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Demand Dispatch
Demand Dispatch
Responsive Regulation and desired QoS – A partial list of the needs of the grid operator, and the consumer
High quality AS? Reliable? Cost effective? Customer QoS constraints satisfied? Virtual energy storage: achieve these goals simultaneously through distributed control
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Demand Dispatch
General Principles for Design
Two components to local control Local feedback loop Local Control Load i
ζt Y i
t
U i
t
Prefilter Decision
ζt U i
t
Xi
t
Xi
t
Each load monitors its state and a regulation signal from the grid. Prefilter and decision rules designed to respect needs of load and grid Randomized policies required for finite-state loads
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Demand Dispatch
MDP model
MDP model The state for a load is modeled as a controlled Markov chain. Controlled transition matrix: Pζ(x, x′) = P{Xt+1 = x′ | Xt = x, ζt = ζ}
Two components to local control Local feedback loop Local Control Load i ζt Y i
t
U i
t
Prefilter Decision ζt U i
t
Xi
t
Xi
t
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Demand Dispatch
MDP model
MDP model The state for a load is modeled as a controlled Markov chain. Controlled transition matrix: Pζ(x, x′) = P{Xt+1 = x′ | Xt = x, ζt = ζ}
Two components to local control Local feedback loop Local Control Load i ζt Y i
t
U i
t
Prefilter Decision ζt U i
t
Xi
t
Xi
t
Questions:
- How to analyze aggregate of similar loads?
- How to design Pζ?
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Demand Dispatch
How to analyze aggregate?
Mean field model
Reference Output deviation (MW) −300 −200 −100 100 200 300 20 40 60 80 100 120 140 160 t/hour 20 40 60 80 100 120 140 160
State process: µt(x) ≈ 1 N
N
- i=1
I{Xi
t = x},
x ∈ X Evolution: µt+1 = µtPζt Output (mean power): yt =
- x
µt(x)U(x) Nonlinear state space model Linearization useful for control design
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Demand Dispatch
Control Architecture
Frequency Allocation for Demand Dispatch
10-2 10-1 100 101 Frequency (rad/s) 10-5 10-4 10-3 Frequency (rad/s) Magnitude (dB)
- 15
- 10
- 5
5 10 15 20 Phase (deg)
- 90
- 45
45
G r i d T r a n s f e r F u n ct i
- n
A typical macro model of the power grid Motivation for PI control architecture, and fear of droop gain
- H. Chavez, R. Baldick, and S. Sharma. Regulation adequacy analysis under high wind penetration scenarios in ERCOT nodal. IEEE Trans. on Sustainable Energy, 3(4):743–750, Oct 2012.
−300 −200 −100
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Demand Dispatch
Control Architecture
Frequency Allocation for Demand Dispatch
10-2 10-1 100 101 Frequency (rad/s) 10-5 10-4 10-3 Frequency (rad/s) Magnitude (dB)
- 15
- 10
- 5
5 10 15 20 Phase (deg)
- 90
- 45
45 G r i d T r a n s f e r F u nc t i
- n
Uncertainty Here
There is significant gain and phase uncertainty in this bandwidth
Fear is justified!
−300 −200 −100
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Demand Dispatch
Control Architecture
Frequency Allocation for Demand Dispatch
10-2 10-1 100 101 Frequency (rad/s) 10-5 10-4 10-3 Frequency (rad/s) Magnitude (dB)
- 15
- 10
- 5
5 10 15 20 Phase (deg)
- 90
- 45
45 G r i d T r a n s f e r F u nc t i
- n
Uncertainty Here Fans in Commercial Buildings
Fans in commercial buildings in the state of Florida can supply all of the RegD and RegA regulation needs of PJM
10 20 30 40 7am 1pm 7pm
Hours Minutes
1am Measured Reference 71
- 1
- 0.5
0.5 1 73 72 74
KW F
- −300
−200 −100
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Demand Dispatch
Control Architecture
Frequency Allocation for Demand Dispatch
10-2 10-1 100 101 Frequency (rad/s) 10-5 10-4 10-3 Frequency (rad/s) Magnitude (dB)
- 15
- 10
- 5
5 10 15 20 Phase (deg)
- 90
- 45
45 G r i d T r a n s f e r F u nc t i
- n
Uncertainty Here Fans in Commercial Buildings Residential Water Heaters Refrigerators
The bandwidth of these devices is centered around their natural cycle the capacity is enormous in this bandwidth
−300 −200 −100
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Demand Dispatch
Control Architecture
Frequency Allocation for Demand Dispatch
10-2 10-1 100 101 Frequency (rad/s) 10-5 10-4 10-3 Frequency (rad/s) Magnitude (dB)
- 15
- 10
- 5
5 10 15 20 Phase (deg)
- 90
- 45
45 G r i d T r a n s f e r F u nc t i
- n
Uncertainty Here Fans in Commercial Buildings Residential Water Heaters Refrigerators Water Pumping Pool Pumps Chiller Tanks
Bandwidth centered around its natural cycle
Reference (from Bonneville Power Authority)
10,000 pools
Output deviation
−300 −200 −100 100 200 300
Tracking BPA Regulation Signal (MW)
20 40 60 80 100 120 140 160 t/hour 20 40 60 80 100 120 140 160
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Demand Dispatch
Control Architecture
Frequency Allocation for Demand Dispatch
−300 −200 −100
10-2 10-1 100 101 Frequency (rad/s) 10-5 10-4 10-3 Frequency (rad/s) Magnitude (dB)
- 15
- 10
- 5
5 10 15 20 Phase (deg)
- 90
- 45
45 G r i d T r a n s f e r F u nc t i
- n
Uncertainty Here Fans in Commercial Buildings Residential Water Heaters Refrigerators Water Pumping Pool Pumps Chiller Tanks
19% of the load Imagine the capacity from water pumping in California?
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Power Grid Control
Water Pump Batteries Coal Gas Turbine
BP BP BP
C
BP BP
Voltage Frequency Phase
H C
Σ −
Actuator feedback loop
A
LOAD
Conclusions
Conclusions
Conclusions
Volatility appears to be manageable! Randomized control architecture designed so that everyone is happy. The virtual storage capacity from demand dispatch is enormous Open questions on many spatial and temporal scales
1 Most loads could provide synthetic inertia and governor response1.
Is this wise?
2 We don’t know why the grid is so reliable today
– we need better macro models2
3 And of course, incentives are needed: contracts and/or standards 1Scweppe et. al. 1980 2Thorpe et. al. 2004 13 / 15
Conclusions
Conclusions
Thank You!
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References
Selected References
- H. Hao, Y. Lin, A. Kowli, P. Barooah, and S. Meyn. Ancillary service to the grid through
control of fans in commercial building HVAC systems. IEEE Trans. on Smart Grid, 5(4):2066–2074, July 2014.
- S. Meyn, P. Barooah, A. Buˇ
si´ c, Y. Chen, and J. Ehren. Ancillary service to the grid using intelligent deferrable loads. ArXiv e-prints: arXiv:1402.4600 and to appear, IEEE Trans. on
- Auto. Control, 2014.
- P. Barooah, A. Buˇ
si´ c, and S. Meyn. Spectral decomposition of demand-side flexibility for reliable ancillary services in a smart grid. In Proc. 48th Annual Hawaii International Conference on System Sciences (HICSS), pages 2700–2709, Kauai, Hawaii, 2015.
- Y. Chen, A. Buˇ
si´ c, and S. Meyn. Individual risk in mean-field control models for decentralized control, with application to automated demand response. In Proc. of the 53rd IEEE Conference on Decision and Control, pages 6425–6432, Dec. 2014.
- A. Buˇ
si´ c and S. Meyn. Passive dynamics in mean field control. 53rd IEEE Conf. on Decision and Control (Invited). 2014.
- J. Mathias, R. Kaddah, A. Buˇ
si´ c, and S. Meyn. Smart fridge / dumb grid? demand dispatch for the power grid of 2020. Proc. 49th Annual Hawaii International Conference on System Sciences (HICSS), Kauai, Hawaii, 2016.
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