AI for a Responsible Power System de faculteit...Arti cial Intelligence can (should) contribute...
Transcript of AI for a Responsible Power System de faculteit...Arti cial Intelligence can (should) contribute...
AI for a Responsible Power System
Mathijs de Weerdt
Associate Professor in Algorithmics group, EEMCS
Delft University of Technology
February 21, 2019
My talk in a nutshell
• Artificial Intelligence can (should) contribute towards a more responsible society.
• Algorithmic innovations can tackle concrete AI challenges in the power system.
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Current Allocation is NotResponsible
• Part of humanity is starving
• Part of humanity consumes too much
• Running out of some of the resources
Mainly caused by optimization of profit.
We need more responsible allocations:
1 more fair across parties
2 better balance of optimal now versuslong-term effects
Does this rise new algorithmic challenges?
Doughnut Economicsby Kate Raworth [2017]
www.kateraworth.com/3 / 27
Current Allocation is NotResponsible
• Part of humanity is starving
• Part of humanity consumes too much
• Running out of some of the resources
Mainly caused by optimization of profit.
We need more responsible allocations:
1 more fair across parties
2 better balance of optimal now versuslong-term effects
Does this rise new algorithmic challenges?
Doughnut Economicsby Kate Raworth [2017]
www.kateraworth.com/3 / 27
Scientific gap
allocation decision support
with interaction
simple well understood
(behavioural) game theory
complex AI & algorithmics
algorithmic game theory
Algorithmic game theory:
• Fair allocation under strict conditions [Bergemann and Valimaki, 2010, Parkeset al., 2010]
• For relevant settings: impossibility theorems [Satterthwaite, 1975].
But these are situations we encounter —and deal with— in practice.
• Can algorithms and AI help to improve this current practice with respect toefficiency, fairness, and longer term consequences. . . ?
• Let’s look at some more concrete computational challenges in the electricity grid.
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Scientific gap
allocation decision support with interactionsimple well understood (behavioural) game theorycomplex AI & algorithmics algorithmic game theory
Algorithmic game theory:
• Fair allocation under strict conditions [Bergemann and Valimaki, 2010, Parkeset al., 2010]
• For relevant settings: impossibility theorems [Satterthwaite, 1975].
But these are situations we encounter —and deal with— in practice.
• Can algorithms and AI help to improve this current practice with respect toefficiency, fairness, and longer term consequences. . . ?
• Let’s look at some more concrete computational challenges in the electricity grid.
4 / 27
Scientific gap
allocation decision support with interactionsimple well understood (behavioural) game theorycomplex AI & algorithmics algorithmic game theory
Algorithmic game theory:
• Fair allocation under strict conditions [Bergemann and Valimaki, 2010, Parkeset al., 2010]
• For relevant settings: impossibility theorems [Satterthwaite, 1975].
But these are situations we encounter —and deal with— in practice.
• Can algorithms and AI help to improve this current practice with respect toefficiency, fairness, and longer term consequences. . . ?
• Let’s look at some more concrete computational challenges in the electricity grid.
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Today’s Electricity System
• Electricity systems support the generation, transport and use of electrical energy.
• They are large and complex and provide for everyone.
Energy generated = energy consumed at all times
How it used to be. . .• demand is predictable (at an aggregate level)
• which generators are used is decided one day in advance (unit commitment)
• minor corrections are made, based on frequency (primary control, secondarycontrol, etc.)
• a market with few actors (energy retailers)
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The Energy Transition
Changes in the power system
• renewable energy is• intermittent• uncertain• uncontrollable• sometimes located in the distribution grid, and• has virtually no marginal costs
• new loads such as heat pumps, airconditioning,and electric vehicles are• significantly larger than other household
demand, and• more flexible (and therefore also less
predictable)
These new loads can also be part of the solution!commons.wikimedia.org/wiki/File:Electric_Car_recharging.jpg
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Consequences for the main stakeholders
Focus on (computational) challenges regarding
1 Wholesale market operators and system operators
2 Aggregators of flexible demand
3 Distribution network operators
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Challenges in Wholesale Market Design
Challenges for Market Operators/Regulators and ISO/TSO
1 more accurate models for bidding and market clearing• use finer granularity, power-based instead of energy-based (Philipsen et al., 2018)• deal with intertemporal dependencies caused by flexible shiftable loads• model stochastic information explicitly
but reasonable models are non-linear: interesting optimization problem
2 allow smaller, local producers and flexible loads (scalability)
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Aggregators of flexible demand
New flexible loads can be used to match renewable generation, but
• consumers do not want to interact with the market, and
• markets do not want every consumer to interact.
Challenges for Aggregators (a new role!): demand-side management
1 design mechanism to interact with consumers with flexible demand
2 interact with both wholesale markets and distribution service/network operator
3 optimize use of (heterogeneous) flexible demand under uncertain prices anduncertain consumer behavior
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Challenges for DSOs
Aim to avoid unnecessary network reinforcement by demand side management toresolve congestion and voltage quality issues
Challenges for Distribution network system operators
1 (Close to) real-time coordination of generation, storage and flexible loads ofself-interested agents to stay within network capacity limitations:• more agents than in traditional energy market• interaction with wholesale markets• communication may not be always reliable• more complex power flow computations (losses and limitations more relevant in
distribution)
2 Long-term decision making under uncertainty
Some of these challenges we take up in our research.
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Challenges for DSOs
Aim to avoid unnecessary network reinforcement by demand side management toresolve congestion and voltage quality issues
Challenges for Distribution network system operators
1 (Close to) real-time coordination of generation, storage and flexible loads ofself-interested agents to stay within network capacity limitations:• more agents than in traditional energy market• interaction with wholesale markets• communication may not be always reliable• more complex power flow computations (losses and limitations more relevant in
distribution)
2 Long-term decision making under uncertainty
Some of these challenges we take up in our research.
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Research on Responsible Multi-Party Optimization
Mission: to design (and understand fundamental properties of) planning andcoordination algorithms for responsible optimization across organizational boundaries
Scientific challenges in responsible multi-party optimization
• efficiency (optimality) and scalability,
• fairness, and
• accounting for both long- and short-term effects.
Example: Using Flexibility of Heat Pumps to Prevent Congestion (from the perspectiveof an aggregator working closely with network operator)
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Research on Responsible Multi-Party Optimization
Mission: to design (and understand fundamental properties of) planning andcoordination algorithms for responsible optimization across organizational boundaries
Scientific challenges in responsible multi-party optimization
• efficiency (optimality) and scalability,
• fairness, and
• accounting for both long- and short-term effects.
Example: Using Flexibility of Heat Pumps to Prevent Congestion (from the perspectiveof an aggregator working closely with network operator)
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Heat Pumps to Prevent Congestionwith Frits de Nijs, Erwin Walraven, and Matthijs Spaan [de Nijs et al., 2015, 2017, 2018a,b, 2019]
De Teuge (near Zutphen)
• pilot sustainable district in 2003
• heatpumps for heating
But: at peak (cold) times, overload of electricity infrastructure
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Potential Solutions
1 Reinforce network to cope with peak load
2 Optimal scheduling of demand
3 Re-allocation and online coordination
4 Pre-allocation and minimizing violations
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2. Optimal SchedulingFormulate as a mixed integer problem (MIP)
• decide when to turn on or off heat pump
• minimise discomfort (fair: squared distance to temperature set point)
• subject to physical characteristics and capacity constraint
MIP formulation
minimize[ act0 act1 ··· acth ]
h∑t=1
cost(θt ,θsett ) (discomfort)
subject to θt+1 = temperature(θt , actt , θoutt )
n∑i=1
acti,t ≤ capacityt
acti,t ∈ [off,on] ∀i , t
This scales poorly (binary decision variables: houses × time slots).But that is not the only problem. . .
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2. Optimal SchedulingFormulate as a mixed integer problem (MIP)
• decide when to turn on or off heat pump
• minimise discomfort (fair: squared distance to temperature set point)
• subject to physical characteristics and capacity constraint
MIP formulation
minimize[ act0 act1 ··· acth ]
h∑t=1
cost(θt ,θsett ) (discomfort)
subject to θt+1 = temperature(θt , actt , θoutt )
n∑i=1
acti,t ≤ capacityt
acti,t ∈ [off,on] ∀i , t
This scales poorly (binary decision variables: houses × time slots).But that is not the only problem. . .
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3. Re-allocation and online coordinationNot everything is known in advance (heat loss, available capacity), so adaptation maybe required
Arbitrage with Best Response (BR)
1 Plan each thermostat individually, as if unconstrained.
2 Look at the expected plan utility to determine action
3 Determine resource costs per time slot
4 Re-plan including these costs
→ Iterative process
→ Inspired by Brown’s Fictitious Play
Keep all past realizations to ensure convergence
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3. Re-allocation and online coordinationNot everything is known in advance (heat loss, available capacity), so adaptation maybe required
Arbitrage with Best Response (BR)
1 Plan each thermostat individually, as if unconstrained.
2 Look at the expected plan utility to determine action
3 Determine resource costs per time slot
4 Re-plan including these costs
→ Iterative process
→ Inspired by Brown’s Fictitious Play
Keep all past realizations to ensure convergence
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3. Re-allocation and online coordination
Simulation of anextreme scenario
• 182 households
• almost nocapacity forheating 18–24hours
Close to lower boundon optimal (relaxedMIP)
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20
21
22
0 6 12 18 24 30 36 42 48
0.00
0.25
0.50
0.75
1.00
0 6 12 18 24 30 36 42 48
0
50
100
150
0 6 12 18 24 30 36 42 48
Solver
No planning
arbitrage−BR
Relaxed MIP
19
20
21
22
0 6 12 18 24 30 36 42 48
0.00
0.25
0.50
0.75
1.00
0 6 12 18 24 30 36 42 48
0
50
100
150
0 6 12 18 24 30 36 42 48
Solver
No planning
arbitrage−BR
Relaxed MIP
Dev
ices
on(#
)
Avg
.T
emp
.(◦
C)
Cu
mu
lati
vep
enal
ty
Time (h) 19 / 27
3. Re-allocation and online coordination
Simulation of anextreme scenario
• 182 households
• almost nocapacity forheating 18–24hours
Close to lower boundon optimal (relaxedMIP)
19
20
21
22
0 6 12 18 24 30 36 42 48
0.00
0.25
0.50
0.75
1.00
0 6 12 18 24 30 36 42 48
0
50
100
150
0 6 12 18 24 30 36 42 48
Solver
No planning
arbitrage−BR
Relaxed MIP
19
20
21
22
0 6 12 18 24 30 36 42 48
0.00
0.25
0.50
0.75
1.00
0 6 12 18 24 30 36 42 48
0
50
100
150
0 6 12 18 24 30 36 42 48
Solver
No planning
arbitrage−BR
Relaxed MIP
Dev
ices
on(#
)A
vg.
Tem
p.
(◦C
)C
um
ula
tive
pen
alty
Time (h) 19 / 27
3. Re-allocation and online coordination: runtime
1 2 3 4 5 6 10 15 20 25 30 35 40 45
10−2
10−1
100
101
102
Solver
arbitrage−BR
Optimal MMDP
Optimal MIP
Ru
nti
me
(s)
Agents (n) Horizon (h)
Close to optimal, good scaling, but reliable communication is essential. . .
Pre-allocate time-dependent limits per agent that limit probability of violations.
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4. Pre-allocation and minimizing violations
Robust pre-allocation of available capacity (Wu and Dur-fee, 2010)
Frequen
cy
L
Satisfying Limits in Expectation (CMDP, Altman 1999)
Frequen
cy
L
Reduced Limits with Hoeffding’s inequality given α
Frequen
cy
L∗ L
Dynamic Relaxation of Reduced Limits by Simulation(De Nijs et al., 2017–2018)
Frequen
cy
L∗ L L
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Simulations and Extensions
• Dynamic pre-allocation: efficient, tightlybounded violation probability, and scalable
Extensions• Re-run in case new information (and
communication) is available
• Include wholesale electricity prices to useflexibility for balancing (within constraints)
• Include electric vehicles (and other flexibleloads)
Toolbox available (soon):github.com/AlgTUDelft/ConstrainedPlanningToolbox
PhD Defense and seminar: April 4, 2019
Alg.MILPLDD+GAPS
CMDPHoeffding (CMDP), α = 0.05
Dynamic (CMDP), α = 0.005Dynamic (CG), α = 0.005
100
8
16
32
64
TCL, h = 24
Vio
latio
ns
0.005
0.050
0.5001.000
10−2
10−1
100
101
102
103
4 8 16 32 64 128 256
Num. Agents
% E
x.
Va
lue
Ru
ntim
e (
s.)
Alg.MILPLDD+GAPS
CMDPHoeffding (CMDP), α = 0.05
Dynamic (CMDP), α = 0.005Dynamic (CG), α = 0.005
100
8
16
32
64
TCL, h = 24
Vio
latio
ns
0.005
0.050
0.5001.000
10−2
10−1
100
101
102
103
4 8 16 32 64 128 256
Num. Agents
% E
x. V
alu
eR
untim
e (
s.)
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Simulations and Extensions
• Dynamic pre-allocation: efficient, tightlybounded violation probability, and scalable
Extensions• Re-run in case new information (and
communication) is available
• Include wholesale electricity prices to useflexibility for balancing (within constraints)
• Include electric vehicles (and other flexibleloads)
Toolbox available (soon):github.com/AlgTUDelft/ConstrainedPlanningToolbox
PhD Defense and seminar: April 4, 2019
Alg.MILPLDD+GAPS
CMDPHoeffding (CMDP), α = 0.05
Dynamic (CMDP), α = 0.005Dynamic (CG), α = 0.005
100
8
16
32
64
TCL, h = 24
Vio
latio
ns
0.005
0.050
0.5001.000
10−2
10−1
100
101
102
103
4 8 16 32 64 128 256
Num. Agents
% E
x.
Va
lue
Ru
ntim
e (
s.)
Alg.MILPLDD+GAPS
CMDPHoeffding (CMDP), α = 0.05
Dynamic (CMDP), α = 0.005Dynamic (CG), α = 0.005
100
8
16
32
64
TCL, h = 24
Vio
latio
ns
0.005
0.050
0.5001.000
10−2
10−1
100
101
102
103
4 8 16 32 64 128 256
Num. Agents
% E
x. V
alu
eR
untim
e (
s.)
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Simulations and Extensions
• Dynamic pre-allocation: efficient, tightlybounded violation probability, and scalable
Extensions• Re-run in case new information (and
communication) is available
• Include wholesale electricity prices to useflexibility for balancing (within constraints)
• Include electric vehicles (and other flexibleloads)
Toolbox available (soon):github.com/AlgTUDelft/ConstrainedPlanningToolbox
PhD Defense and seminar: April 4, 2019
Alg.MILPLDD+GAPS
CMDPHoeffding (CMDP), α = 0.05
Dynamic (CMDP), α = 0.005Dynamic (CG), α = 0.005
100
8
16
32
64
TCL, h = 24
Vio
latio
ns
0.005
0.050
0.5001.000
10−2
10−1
100
101
102
103
4 8 16 32 64 128 256
Num. Agents
% E
x.
Va
lue
Ru
ntim
e (
s.)
Alg.MILPLDD+GAPS
CMDPHoeffding (CMDP), α = 0.05
Dynamic (CMDP), α = 0.005Dynamic (CG), α = 0.005
100
8
16
32
64
TCL, h = 24
Vio
latio
ns
0.005
0.050
0.5001.000
10−2
10−1
100
101
102
103
4 8 16 32 64 128 256
Num. Agents
% E
x. V
alu
eR
untim
e (
s.)
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Our Other Contributions to the Smart Grid
• Scheduling of charging of electric vehicles:• Computational complexity [de Weerdt et al., 2018]• Stochastic optimization [van der Linden et al., 2018]• En-route charging [de Weerdt et al., 2016]
• Market design:• Auction design for DC grids [Piao et al., 2018, 2017]• Design errors in existing markets [Philipsen et al., 2019]
• Combined: Online scheduling mechanism for flexible loads [Strohle et al., 2014]
• Long-term investments: Unbounded MDPs [Neustroev et al., 2019]
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Conclusions
Concluding Observations
• AI and algorithms can contribute to aresponsible operation of commoninfrastructure
• More research required on fairness,incentives in market design, and effects onthe future!
Slides are available from
www.alg.ewi.tudelft.nl/weerdt/
Thanks a lot to Matthijs, Frits, Erwin, Rens, Laurens, German, Natalia, Greg, Koos,Anna, Longjian, Neil, Gleb, Jedlix, Alliander, Eneco, and all my (other) students andcollaborators!
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References I
D. Bergemann and J. Valimaki. The dynamic pivot mechanism. Econometrica, 78(2):771–789, 2010.
F. de Nijs, M. Spaan, and M. de Weerdt. Best-Response Planning of Thermostatically ControlledLoads under Power Constraints. In Proceedings of the 29th AAAI Conference on ArtificialIntelligence, pages 615–621, 2015.
F. de Nijs, E. Walraven, M. T. Spaan, and M. M. de Weerdt. Bounding the Probability of ResourceConstraint Violations in Multi-Agent MDPs. Proc. AAAI 2017, 2017.
F. de Nijs, M. Spaan, and M. M. de Weerdt. Preallocation and Planning under Stochastic ResourceConstraints. In Proceedings of the 32th AAAI Conference on Artificial Intelligence. Association forthe Advancement of Artificial Intelligence (AAAI), Jan. 2018a.
F. de Nijs, G. Theocharous, N. Vlassis, M. de Weerdt, and M. Spaan. Capacity-aware SequentialRecommendations. In Proceedings of the 17th International Conference on Autonomous Agents andMultiagent Systems, pages 416–424. International Foundation for Autonomous Agents andMultiagent Systems (IFAAMAS), July 2018b.
F. de Nijs, M. T. J. Spaan, and M. M. de Weerdt. Multi-agent Planning Under Uncertainty forCapacity Management. In P. Palensky, M. Cvetkovic, and T. Keviczky, editors, Intelligent IntegratedEnergy Systems, pages 197–213. Springer, Cham, 2019.
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References IIM. de Weerdt, M. Albert, V. Conitzer, and K. van der Linden. Complexity of Scheduling Charging in
the Smart Grid. In Proceedings of the Twenty-Seventh International Joint Conference on ArtificialIntelligence, pages 4736–4742, California, July 2018. International Joint Conferences on ArtificalIntelligence (IJCAI).
M. M. de Weerdt, S. Stein, E. H. Gerding, V. Robu, N. R. Jennings, and M. M. de Weerdt.Intention-aware routing of electric vehicles. IEEE Transactions on Intelligent TransportationSystems, 17(5):1472–1482, 2016.
G. Neustroev, M. M. de Weerdt, and R. A. Verzijlbergh. Discovery of Optimal Solution Horizons inNon-Stationary Markov Decision Processes with Unbounded Rewards. In Proceedings of theInternational Conference on Planning and Scheduling (ICAPS’05), 2019.
D. C. Parkes, R. Cavallo, F. Constantin, and S. Singh. Dynamic incentive mechanisms. AI Magazine,31(4):79–94, 2010.
R. Philipsen, G. Morales-Espana, M. de Weerdt, and L. de Vries. Trading power instead of energy inday-ahead electricity markets. Applied Energy, 233-234:802–815, 2019.
L. Piao, M. de Weerdt, and L. de Vries. Electricity market design requirements for DC distributionsystems. In 2017 IEEE Second International Conference on DC Microgrids (ICDCM, pages 95–101.IEEE, 2017.
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References III
L. Piao, L. de Vries, M. de Weerdt, and N. Yorke-Smith. Electricity Market for Direct CurrentDistribution Systems: Exploring the Design Space. In Proceedings of the 15th InternationalConference on the European Energy Market, EEM’18, pages 1–5, United States, 2018. IEEE.
K. Raworth. Doughnut Economics. Seven Ways to Think Like a 21st-Century Economist. 2017.
M. A. Satterthwaite. Strategy-proofness and Arrow’s conditions: Existence and correspondencetheorems for voting procedures and social welfare functions. Journal of economic theory, 10(2):187–217, 1975.
P. Strohle, E. H. Gerding, M. M. de Weerdt, S. Stein, and V. Robu. Online mechanism design forscheduling non-preemptive jobs under uncertain supply and demand. In Proceedings of the 2014international conference on Autonomous agents and multi-agent systems, pages 437–444, 2014.
K. van der Linden, M. de Weerdt, and G. Morales-Espana. Optimal non-zero Price Bids for EVs inEnergy and Reserves Markets using Stochastic Optimization. In Proceedings of the 15thInternational Conference on the European Energy Market, EEM 2018, pages 1–5, United States,2018. IEEE.
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