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From Neural Networks to From Neural Networks to the Intelligent Power the Intelligent Power Grid: What It Takes to Grid: What It Takes to Make Things Work Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do we need neural networks? How can we make neural nets really work here, & in diagnostics/”prediction”/”control” in general? Paul J. Werbos, [email protected] •“Government public domain”: These slides may be copied, posted, or distributed freely, so long as they are kept together, including this notice. But all views herein are personal, unofficial.

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Page 1: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

From Neural Networks to the From Neural Networks to the Intelligent Power Grid: What It Intelligent Power Grid: What It Takes to Make Things WorkTakes to Make Things Work

What is an Intelligent Power Grid, and why do we need it?

Why do we need neural networks?How can we make neural nets really work here,

& in diagnostics/”prediction”/”control” in general?

Paul J. Werbos, [email protected]

•“Government public domain”: These slides may be copied, posted, or distributed freely, so long as they are kept together, including this notice. But all views herein are personal, unofficial.

Page 2: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

National Science Foundation

EngineeringDirectorate

Computer & Info.Science Directorate

ECS IIS

Control,Networks andComputational

Intelligence

EPDT:Chips,Optics,

Etc.

Robotics AI

Information Technology Research (ITR)

Page 3: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

What is a Truly Intelligent Power Grid?What is a Truly Intelligent Power Grid? True intelligence (like brain) foresight, ability to learn to coordinate

all pieces, for optimal expected performance on the bottom line in future despite random disturbances.

Managing complexity is easy– if you don’t aim for best possible performance! The challenge is to come as close as possible to optimal performance of whole system.

Bottom line utility function includes value added, quality of service (reliability), etc. A general concept. Nonlinear robust control is just a special case.

Enhanced communication/chips/sensing/actuation/HPC needed for max benefit(cyberinfrastructure, EPRI roadmap)

Brain-like intelligence = embodied intelligence, AI

Page 4: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Dynamic Stochastic Optimal Power Flow Dynamic Stochastic Optimal Power Flow (DSOPF): How to Integrate the “Nervous (DSOPF): How to Integrate the “Nervous

System” of ElectricitySystem” of Electricity

DSOPF02 started from EPRI question: can we optimally manage&plan the whole grid as one system, with foresight, etc.?

Closest past precedent: Momoh’s OPF integrates &optimizes many grid functions – but deterministic and without foresight. UPGRADE!

ADP math required to add foresight and stochastics, critical to more complete integration.

ANN to I/O From Idealized Power GridANN to I/O From Idealized Power Grid

4 General Object Types (4 General Object Types (busbarbusbar, wire, G, L), wire, G, L)

Net should allow Net should allow arbitrary numberarbitrary numberof the 4 objectsof the 4 objects

How design ANN to input and output FIELDS How design ANN to input and output FIELDS ---- variables like the SET of variables like the SET of values for current ACROSS all objects? values for current ACROSS all objects?

Page 5: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Why It is a Life-or-Death IssueWhy It is a Life-or-Death Issue

As Gas Prices Imports & Nuclear Tech in unstable areas , human extinction is a serious risk. Need to move faster.Optimal time-shifting – big boost to rapid adjustment, $

HOW?

•www.ieeeusa.org/policy/energy_strategy.ppt•Photo credit IEEE Spectrum

Page 6: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Why It Requires Artificial Neural Why It Requires Artificial Neural Networks (ANNs)Networks (ANNs)

For optimal performance in the general nonlinear case (nonlinear control strategies, state estimators, predictors, etc…), we need to adaptively estimate nonlinear functions. Thus we must use universal nonlinear function approximators.

Barron (Yale) proved basic ANNs (MLP) much better than Taylor series, RBF, etc., to approximate smooth functions of many inputs. Similar theorems for approximating dynamic systems, etc., especially with more advanced, more powerful, MLP-like ANNs.

ANNs more “chip-friendly” by definition: Mosaix chips, CNN here today, for embedded apps, massive thruput

Page 7: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Neural Networks That Actually Work In Neural Networks That Actually Work In Diagnostics, Prediction & Control: Common Diagnostics, Prediction & Control: Common

Misconceptions Vs. Real-World SuccessMisconceptions Vs. Real-World Success

Neural Nets, A Route to Learning/Intelligence– goals, history, basic concepts, consciousness

State of the Art -- Working Tools Vs. Toys and Fads– static prediction/classification– dynamic prediction/classification– control: cloning experts, tracking, optimization

Advanced Brain-Like Capabilities & Grids

Page 8: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Neural Nets: The Link Between Neural Nets: The Link Between VisionVision, , ConsciousnessConsciousness and and

Practical ApplicationsPractical Applications

“Without vision, the people perish....”

What is a Neural Network? -- 4 definitions:“MatLab,” universal approximators,

6th generation computing, brain-like computingWhat is the Neural Network Field All About? How Can We Get Better Results

in Practical Applications?

Page 9: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Generations of ComputersGenerations of Computers

¤ 4th Gen: Your PC. One VLSI CPU chip executes one sequential stream of C code.

¤ 5th Gen: “MPP”, “Supercomputers”: Many CPU chips in 1 box. Each does 1 stream. HPCC.

¤ 6th Gen or “ZISC.” Ks or Millions of simple streams per chip or optics. Neural nets may be defined as designs for 6th gen + learning. (Psaltis, Mead.)¤ New interest; Moore, SRC; Mosaix, JPL sugarcube, CNN.

¤ 7th Gen: Massively parallel quantum computing? General? Grover like Hopfield?

Page 10: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

The Brain As a Whole System Is an Intelligent Controller

Action

Reinforcement

Sensory Input

Page 11: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Unified Neural Network Unified Neural Network DesignsDesigns::

The Key to Large-Scale The Key to Large-Scale ApplicationsApplications

& Understanding the Brain& Understanding the Brain

Page 12: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Electrical and Communications Systems(ECS)Cyber Infrastructure Investments

Electrical and Communications Systems(ECS)Cyber Infrastructure Investments

Town Hall Meeting – October 29, 2003

The Physical Layer – Devices and Networks– National Nanofabrication Users Network (NNUN)– Ultra-High-Capacity Optical Communications and Networking– Electric Power Sources, Distributed Generation and Grids

Information Layer – Algorithms, Information and Design– General tools for distributed, robust, adaptive, hybrid control & related

tools for modeling, system identification, estimation– General tools for sensors-to-information & to decision/control– Generality via computational intelligence, machine learning, neural

networks & related pattern recognition, data mining etc.

Integration of Physical Layer and Information Layer– Wireless Communication Systems– Self-Organizing Sensor and Actuator Networks– System on Chip for Information and Decision Systems– Reconfigurable Micro/Nano Sensor Arrays– Efficient and Secure Grids and Testbeds for Power Systems

Page 13: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Sensing Comm Control

Self-ConfiguringHW Modules

CoordinatedSW ServiceComponents

Cyberinfrastructure: The Entire Web From SensorsCyberinfrastructure: The Entire Web From SensorsTo Decisions/Actions/Control For Max PerformanceTo Decisions/Actions/Control For Max Performance

Page 14: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Levels of Intelligence

Reptile

Symbolic

Bird

Mammal

?

Human

Page 15: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Why Engineers Need This Vision:

1. To Keep Trackof MANY Tools

2. To DevelopNew Tools -- ToDo Good R&D& Make MaxContribution

3. To Attract &Excite the BestStudents

4. Engineers areHuman Too...

Page 16: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Where Did ANNs Come From?Where Did ANNs Come From?

SpecificProblemSolvers

General Problem Solvers McCullochPitts Neuron

LogicalReasoningSystems

ReinforcementLearning

Widrow LMS&Perceptrons

Expert Systems

Minsky

Backprop ‘74

Psychologists, PDP Books

ComputationalNeuro, HebbLearning Folks

IEEE ICNN 1987: Birth of a “Unified” Discipline

Page 17: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Hebb 1949: Intelligence As AnHebb 1949: Intelligence As AnEmergentEmergent Phenomenon or Phenomenon or

LearningLearning“The general idea is an old one,that any two cells or systems of cells that are especially activeat the same time will tend to become ‘associated,’ so thatactivity in one facilitatesactivity in the other” -- p.70(Wiley 1961 printing)

The search for the GeneralNeuron Model (of Learning)

“Solves all problems”

Page 18: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Claim (1964) : Hebb’s Claim (1964) : Hebb’s Approach Doesn’t Quite Work Approach Doesn’t Quite Work

As StatedAs Stated Hebbian Learning Rules Are All Based on

Correlation Coefficients Good Associative Memory: one component of the

larger brain (Kohonen, ART, Hassoun) Linear decorrelators and predictors Hopfield f(u) minimizers never scaled, but:

– Gursel Serpen and SRN minimizers– Brain-Like Stochastic Search (Needs R&D)

Page 19: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Understanding Brain RequiresModels Tested/Developed

Using Multiple Sources of Info

• Engineering: Will it work? Mathematics understandable, generic?

• Psychology: Connectionist cognitive science, animal learning, folk psychology

• Neuroscience: computational neuroscience

• AI: agents, games (backgammon, go), etc.

• LIS and CRI

Page 20: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

1971-2: Emergent Intelligence Is Possible1971-2: Emergent Intelligence Is PossibleIf We Allow Three Types of Neuron If We Allow Three Types of Neuron

(Thesis,Roots)(Thesis,Roots)

Critic

Model

Action

J(t+1)

R(t+1)

u(t)

X(t)

R(t)Red Arrows:DerivativesCalculated ByGeneralizedBackpropagation

Page 21: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Harvard Committee ResponseHarvard Committee Response

We don’t believe in neural networks – see Minsky (Anderson&Rosenfeld, Talking Nets)

Prove that your backwards differentiation works. (That is enough for a PhD thesis.) The critic/DP stuff published in ’77,’79,’81,’87..

Applied to affordable vector ARMA statistical estimation, general TSP package, and robust political forecasting

Page 22: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

SYSTEM

Y, a scalar result

x1

xn

.

.

.

(Inputs xk may actually come from many times)

+YxK

W

Backwards Differentiation: But what kindsof SYSTEM can we handle? See details in AD2004 Proceedings, Springer, in press.

Page 23: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do
Page 24: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

To Fill IN the Boxes:To Fill IN the Boxes:(1) NEUROCONTROL, to Fill in Critic or (1) NEUROCONTROL, to Fill in Critic or

Action;Action;(2) System Identification or Prediction(2) System Identification or Prediction(Neuroidentification) to Fill In Model(Neuroidentification) to Fill In Model

Critic

Model

Action

J(t+1)

R(t+1)

u(t)

X(t)

R(t)Red Arrows:DerivativesCalculated ByGeneralizedBackpropagation

Page 25: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

NSF Workshop Neurocontrol 1988NSF Workshop Neurocontrol 1988

Miller, Sutton, Werbos, MIT Press, 1990

ControlTheory

Neuro-Engineering

Neuro-Control

Neurocontrol is NOT JUST Control Theory!

Page 26: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

NSF/McAir Workshop 1990

White and Sofge eds, Van Nostrand, 1992

Page 27: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

““What Do Neural Nets & What Do Neural Nets & QuantumQuantum

Theory Tell Us About Mind & Theory Tell Us About Mind & Reality?”Reality?”

In Yasue et al (eds),In Yasue et al (eds),No Matter, Never Mind -- Proc.No Matter, Never Mind -- Proc.

Of Towards a Science of Of Towards a Science of ConsciousnessConsciousness, John Benjamins, John Benjamins(Amsterdam), 2001 & arxiv.org(Amsterdam), 2001 & arxiv.org

Page 28: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

3 Types of Diagnostic System3 Types of Diagnostic System

All 3 train predictors, use sensor data X(t), other data u(t), fault classifications F1 to Fm

Type 1: predict Fi(t) from X(t), u(t), MEMORY

Others: first train to predict X(t+1) from X,u,MEM– Type 2: when actual X(t+1) 6 from prediction, ALARM– Type 3: if prediction net predicts BAD X(t+T), ALARM

Combination best. See PJW in Maren, ed, Handbook

Neural Computing Apps, Academic, 1990.

Page 29: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Supervised Learning Systems (SLS)

SLSu(t)inputs

Predicted X(t)outputs

Actual X(t)targets

SLS may have internal dynamics but no “memory” of times t-1, t-2...

Page 30: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

F(t-3) F(t-2) F(t-1) pH(t-3) pH(t-2) pH(t-1)

pH(t)

Example of TDNN used in HIC, Chapter 10TDNNs learn NARX or FIR Models, not NARMAX or IIR

Page 31: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

CONVENTIONAL ANNS USED FOR CONVENTIONAL ANNS USED FOR FUNCTION APPROXIMATION IN FUNCTION APPROXIMATION IN

CONTROLCONTROL

• Global: Multilayer Perceptron (MLP)— Better Generalization, Slower Learning

— Barron’s Theorems: More Accurate Approximation of

Smooth Functions as Number of Inputs Grows

• Local: RBF, CMAC, Hebbian— Like Nearest Neighbor, Associative Memory

— Sometimes Called “Glorified Lookup tables”

Page 32: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Generalized MLPGeneralized MLP

0 1 m m + 1 N N + 1 N + n

Inputs Outputs

1 x1 xm Y1 Yn

Page 33: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

No feedforward or associative No feedforward or associative memory net can give brain-likememory net can give brain-like

performance! Useful performance! Useful recurrence--recurrence--

For short-term memory, for state estimation, for fast adaptation – time-lagged recurrence needed. (TLRN = time-lagged recurrent net)

For better Y=F(X,W) mapping, Simultaneous Recurrent Networks Needed. For large-scale tasks, SRNs WITH SYMMETRY tricks needed – cellular SRN, Object Nets

For robustness over time, “recurrent training”

Page 34: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Why TLRNs Vital in Prediction: Why TLRNs Vital in Prediction: Correlation Correlation Causality! Causality!

E.g.: law X sends extra $ to schools with low test scores

Does negative correlation of $ with test scores imply X is a bad program? No! Under such a law, negative correlation is hard-wired. Low test scores cause $ to be there! No evidence + or – re the program effect!

Solution: compare $ at time t with performance changes from t to t+1! More generally/accurately: train dynamic model/network – essential to any useful information about causation or for decision!

Page 35: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

The Time-Lagged The Time-Lagged Recurrent Network (TLRN)Recurrent Network (TLRN)

Any Static Network

z-1

X(t)

R(t-1)

Y(t)

R(t-1)

Y(t)=f(X(t), R(t-1)); R(t)=g(X(t), R(t-1))f and g represent 2 outputs of one networkAll-encompassing, NARMAX(1 n)Felkamp/Prokhorov Yale03: >>EKF, hairy

Page 36: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

4(4(55) Ways to Train TLRNs ) Ways to Train TLRNs (SRN)(SRN)

(arXiv.org, adap-org 9806001)(arXiv.org, adap-org 9806001) “Simple BP” – incorrect derivatives due to

truncated calaculation, robustness problem BTT – exact, efficient, see Roots of BP (’74), but

not brain-like (back time calculations) Forward propagation – many kinds (e.g, Roots,

ch.7, 1981) – not brainlike, O(nm) Error Critic– see Handbook ch. 13, Prokhorov Simultaneous BP – SRNS only.

Page 37: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

4 Training Problems Recurrent 4 Training Problems Recurrent NetsNets

Bugs – need good diagnostics“Bumpy error surface” – Schmidhuber says

is common, Ford not. Sticky neuron, RPROP, DEFK (Ford), etc.

Shallow plateaus – adaptive learning rate, DEKF etc., new in works…

Local minima – shaping, unavoidable issues, creativity

Page 38: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

GENERALIZED MAZE PROBLEMGENERALIZED MAZE PROBLEM

NETWORK

Jhat(ix,iy) for all 0<ix,iy<N+1 (an N by N array)

Maze Description - Obstacle (ix,iy) all ix,iy - Goal (ix,iy) all ix,iy

At arXiv.org, nlin-sys, see adap-org 9806001

Page 39: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

4 3 2 1 2

5 1 0 1

6 7 1 2

7 8 7 3

8 7 6 5 4

Page 40: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do
Page 41: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

IDEA OF SRN: TWO TIME INDICES t vs. IDEA OF SRN: TWO TIME INDICES t vs. nn

1st MovieFrame,X(t=1)

1st MovieFrameX(t=1) Net Net

2nd MovieFrameX(t=2)

Net Net

y(0)

y(0)

y(1)(1)

y(1)(2)

y(2)(1)

y(2)(2)

Yhat(1)=y(20)(1)

Page 42: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

ANN to I/O From Idealized Power ANN to I/O From Idealized Power GridGrid

4 General Object Types (busbar, wire, G, L) Net should allow arbitrary number of the 4 objects How design ANN to input and output FIELDS -- variables like the

SET of values for current ACROSS all objects?

Page 43: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Training: Brain-Style Prediction Is Training: Brain-Style Prediction Is NOT Just Time-Series Statistics!NOT Just Time-Series Statistics!

One System does it all -- not just a collection of chapters or methods

Domain-specific info is 2-edged sword:– need to use it; need to be able to do without it

Neural Nets demand/inspire new work on general-purpose prior probabilities and on dynamic robustness (See HIC chapter 10)

SEDP&Kohonen: general nonlinear stochastic ID of partially observed systems

Page 44: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Three Approaches to Three Approaches to PredictionPrediction

Bayesian: Maximize Pr(Model|data)– “Prior probabilities” essential when many inputs

Minimize “bottom line” directly– Vapnik: “empirical risk” static SVM and “sytructural risk”

error bars around same like linear robust control on nonlinear system

– Werbos ’74 thesis: “pure robust” time-series Reality: Combine understanding and bottom line.

– Compromise method (Handbook)– Model-based adaptive critics

Suykens, Land????

Page 45: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

F(t-3) F(t-2) F(t-1) pH(t-3) pH(t-2) pH(t-1)

pH(t)

Example of TDNN used in HIC, Chapter 10TDNNs learn NARX or FIR Models, not NARMAX or IIR

Page 46: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Prediction Errors (HIC Prediction Errors (HIC p.319)p.319)

0

5

10

15

20

25

30

35

40

Pretreater Sedimentation Average

Conventional

Pure Robust

Page 47: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

PURE ROBUST METHODPURE ROBUST METHOD

Model Network

Model Network

Error

X(t)

X(t)X(t)

X(t+1)

Error

X(t+1)

X(t-1)

u(t)

u(t-1)

Page 48: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

NSF Workshop Neurocontrol NSF Workshop Neurocontrol 19881988

Miller, Sutton, Werbos, MIT Press, 1990

ControlTheory

Neuro-Engineering

Neuro-Control

Neurocontrol is NOT JUST Control Theory!

Page 49: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

What Is Control?What Is Control?

Plant or Environment

z-1

Control system

R

Control Variables (Actions) u(t)

Observables X(t)

• t may be discrete (0, 1, 2, ...) or continuous• “Decisions” may involve multiple time scales

Page 50: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Major Choices In Control (A Major Choices In Control (A Ladder)Ladder)

•SISO (old) versus. MIMO (modern & CI)

•Feedforward versus Feedback

•Fixed versus Adaptive versus Learning

— e.g learn to adapt to changing road traction

•Cloning versus Tracking versus Optimization

Page 51: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

3 Design 3 Design Approaches/Goals/TasksApproaches/Goals/Tasks

•CLONING: Copy Expert or Other Controller

— What the Expert Says (Fuzzy or AI)

— What the Expert Does (Prediction of Human)

•TRACKING: Set Point or Reference Trajectory

— 3 Ways to Stabilize; To Be Discussed

•OPTIMIZATION OVER TIME

— n-step Lookahead vs. LQG (Stengel, Bryson/Ho)

— vs. Approximate Dynamic Programming (Werbos)

Page 52: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

NSF-NASA Workshop on Learning/RoboticsFor Cheaper (Competitive) Solar Power

See NSF 02-098 at www.nsf.gov &URLs

Page 53: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Human mentors robot and then Human mentors robot and then robot improves skillrobot improves skill

Learning allowed robot to quickly learn to imitatehuman, and then improveagile movements (tennisstrokes). Learning many agile movements quickly will be crucial to enabling >80% robotic assembly in space.

Schaal, AtkesonNSF ITR project

Page 54: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Three Ways To Get StabilityThree Ways To Get StabilityRobust or H Infinity Control

(Oak Tree)Adaptive Control (Grass)Learn Offline/Adaptive Online

(Maren 90)– “Multistreaming” (Ford, Felkamp et al)– Need TLRN Controller, Noise Wrapper– ADP Versions: Online or “Devil Net”

Page 55: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Example from Hypersonics:Example from Hypersonics:Parameter Ranges for Stability (HParameter Ranges for Stability (H))

Center of Gravity at 12 Meters

Center of Gravity at 11.3 Meters

2

1

Page 56: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Idea of Indirect Adaptive Idea of Indirect Adaptive ControlControl

Error =(X - Xr)2

Desired “State” Xr(t+1)

ActionNetwork

ModelNetwork

X(t+1)u(t)

Actual State R(t)

Derivatives of Error(Backpropagated)

Page 57: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Backpropagation Through Time Backpropagation Through Time (BTT) for Control (Neural MPC)(BTT) for Control (Neural MPC)

Error =(X - Xr)2

ActionNetwork

ModelNetwork

u(t) ActionNetwork

ModelNetwork

Error =(X - Xr)2

Predicted X(t)

Predicted X(t+1)

u(t+1)Xr(t+1)

Xr(t)

Page 58: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Level 3 (HDP+BAC) Adaptive Critic Level 3 (HDP+BAC) Adaptive Critic SystemSystem

Critic

Model

Action

J(t+1)

R(t+1)

u(t)

X(t)

R(t)

Page 59: From Neural Networks to the Intelligent Power Grid: What It Takes to Make Things Work What is an Intelligent Power Grid, and why do we need it? Why do

Reinforcement Learning Systems (RLS)

RLS

ExternalEnvironment

or “Plant”“utility” or “reward”or “reinforcement”

U(t)

u(t)actions

X(t)sensor inputs

RLS may have internal dynamics and “memory” of earlier times t-1, etc.

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Maximizing utility over timeMaximizing utility over time

Dynamic programmingDynamic programming

Model of realityModel of reality Utility function UUtility function U

Secondary, or strategic utility function JSecondary, or strategic utility function J

J ( x ( t ) ) M a x

u ( t )

U ( x ( t ) , u ( t ) ) J ( x ( t 1 )) /( 1 r )

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Beyond Bellman: Learning & Beyond Bellman: Learning & Approximation for Optimal Management Approximation for Optimal Management

of Larger Complex Systemsof Larger Complex Systems Basic thrust is scientific. Bellman gives exact optima for

1 or 2 continuous state vars. New work allows 50-100 (thousands sometimes). Goal is to scale up in space and time -- the math we need to know to know how brains do it. And unify the recent progress.

Low lying fruit -- missile interception, vehicle/engine control, strategic games

New book from ADP02 workshop in Mexico www.eas.asu.edu/~nsfadp (IEEE Press, 2004, Si et al eds)

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Emerging Ways to Get Closer to Emerging Ways to Get Closer to Brain-Like SystemsBrain-Like Systems

IEEE Computational Intelligence (CI) Society, new to 2004, about 2000 people in meetings.

Central goal: “end-to-end learning” from sensors to actuators to maximize performance of plant over future, with general-purpose learning ability.

This is DARPA’s “new cogno” in the new nano-info-bio-cogno convergence

This is end-to-end cyberinfrastructure– See hot link at bottom of www.eng.nsf.gov/ecs

What’s new is a path to make it real

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4 Types of Adaptive Critics4 Types of Adaptive Critics

Model-free (levels 0-2)*– Barto-Sutton-Anderson (BSA) design, 1983

Model-based (levels 3-5)*– Werbos Heuristic dynamic programming with

backpropagated adaptive critic, 1977, Dual heuristic programming and Generalized dual heuristic programming, 1987

Error Critic (TLRN, cerebellum models) 2-Brain, 3-Brain models

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Beyond Bellman: Learning & Beyond Bellman: Learning & Approximation for Optimal Approximation for Optimal

Management of Larger Complex Management of Larger Complex SystemsSystems Basic thrust is scientific. Bellman gives exact

optima for 1 or 2 continuous state vars. New work allows 50-100 (thousands sometimes). Goal is to scale up in space and time -- the math we need to know to know how brains do it. And unify the recent progess.

Low lying fruit -- missile interception, vehicle/engine control, strategic games

Workshops: ADP02 in Mexico ebrains.la.asu.edu/~nsfadp; coordinated workshop on anticipatory optimization for power.

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New Workshop on ADP: New Workshop on ADP: text/notes at text/notes at

www.eas.asu.edu/~nsfadp www.eas.asu.edu/~nsfadp Neural Network Engineering

– Widrow 1st ‘Critic’ (‘73), Werbos ADP/RL (‘68-’87)– Wunsch, Lendaris, Balakrishnan, White, Si,LDW......

Control Theory– Ferrari/Stengel (Optimal), Sastry, Lewis, VanRoy

(Bertsekas/Tsitsiklis),Nonlinear Robust... Computer Science/AI

– Barto et al (‘83), TD, Q, Game-Playing, .......... Operations Research

– Original DP: Bellman, Howard; Powell Fuzzy Logic/Control

– Esogbue, Lendaris, Bien

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Level 3 (HDP+BAC) Adaptive Critic Level 3 (HDP+BAC) Adaptive Critic SystemSystem

Critic

Model

Action

J(t+1)

R(t+1)

u(t)

X(t)

R(t)

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Dual Heuristic Programming Dual Heuristic Programming (DHP)(DHP)

CriticCritic

ModelModel UtilityUtility

ActionAction

R(t+1) (t+1)=J(t+1)/R(t+1)

R(t)Target=*(t)

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Don Wunsch, Texas TechDon Wunsch, Texas TechADP Turbogenerator ControlADP Turbogenerator Control

CAREER 9702251, CAREER 9702251, 9704734, etc.9704734, etc.

Stabilized voltage & reactance under intense disturbance where neuroadaptive & usual methods failed

Being implemented in full-scale experimental grid in South Africa

Best paper award IJCNN99

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Uses of the Main Critic Uses of the Main Critic DesignsDesigns

HDP=TD For DISCRETE set of ChoicesDHP when action variables u are

continuousGDHP when you face a mix of both (but

put zero weight on undefined derivative)See arXiv. org , nlin-sys area, adap-org

9810001 for detailed history, equation, stability

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From Today’s Best ADP to True From Today’s Best ADP to True (Mouse-)Brain-Like Intelligence(Mouse-)Brain-Like Intelligence

ANNs For Distributed/Network I/O: “spatial chunking,” ObjectNets, Cellular SRNs

Ways to Learn Levels of a Hierarchical Decision System – Goals, Decisions

“Imagination” Networks, which learn from domain knowledge how to escape local optima (Brain-Like Stochastic Search BLiSS)

Predicting True Probability Distributions

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ANN to I/O From Idealized Power ANN to I/O From Idealized Power GridGrid

4 General Object Types (busbar, wire, G, L) Net should allow arbitrary number of the 4 objects How design ANN to input and output FIELDS -- variables like the

SET of values for current ACROSS all objects?

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Simple Approach to Grid-Grid Simple Approach to Grid-Grid Prediction in Feedforward (FF) Prediction in Feedforward (FF)

CaseCase

Train 4 FF Nets, one for each TYPE of object, over all data on that object.

E.g.: Predict Busbar(t+1) as function of Busbar(t) and Wire(t) for all 4 wires linked to that busbar (imposing symmetry).

Dortmund diagnostic system uses this ideaThis IMPLICITLY defines a global FF net

which inputs X(t) and outputs grid prediction

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ObjectNets: A Recurrent ObjectNets: A Recurrent Generalization (with patent)Generalization (with patent)

Define a global FF Net, FF, as the combination of local object model networks, as before

Add an auxiliary vector, y, defined as a field over the grid (just like X itself)

The structure of the object net is an SRN:– y[k+1] = FF( X(t), y[k], W)– prediction (e.g. X(t+1)) = g(y[])

Train SRNs as in xxx.lanl.gov, adap-org 9806001 General I/O Mapping -- Key to Value Functions

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Four Advanced CapabilitiesFour Advanced Capabilities

ANNs For Distributed/Network I/O: “spatial chunking,” ObjectNets, Cellular SRNs

Ways to Learn Levels of a Hierarchical Decision System

“Imagination” Networks, which learn from domain knowledge how to escape local optima (Brain-Like Stochastic Search BLiSS)

Predicting True Probability Distributions

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Forms of Temporal ChunkingForms of Temporal ChunkingBrute Force, Fixed “T”, Multiresolution

– “Clock Based Synchronization”, NIST– e.g., in Go, predict 20 moves ahead

Action Schemas or Task Modules– “Event Based Synchronization”:BRAIN– Miller/G/Pribram, Bobrow, Russell, me...

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Lookup Table Adaptive Lookup Table Adaptive Critics 1Critics 1

U1 UN

pN

p1 <U(x)> =

SUM (over i) Ui pi

= UTp or UTx

Where pi = Pr(xi) AND Mij = Pr(xi(t+1) | xi(t))

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Review of Lookup Table Review of Lookup Table Critics 2Critics 2

Bellman: J(x(t)) = <U(x(t)) + J(x(t+1))>

JTx = UTx + JTMx

JT = UT(I-M)-1

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Learning Speed of Critics...Learning Speed of Critics...Usual Way: J(0) = U, J(n+1) = U + MTJ(n)

– After n iterations, J(t) approximates – U(t) + U(t+1) + ... + U(t+n)

DOUBLING TRICK shows one can be faster: JT =UT(I+M) (I+M2) (I+M4)...– After n BIG iterations, J(t) approximates– U(t) + U(t+1) + ... + U(t+2n)

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But: What if M is Sparse, But: What if M is Sparse, Block Structured, and Big??Block Structured, and Big??

M-to-the-2-to-the-nth Becomes a MESSInstead use the following equation, the key

result for the flat lookup table case:

JiT = (Ji

A)T +SUM (over j in N(i)) JJT(JB )i

J

where JA represents utility within valley i before exit,and JB works back utility from the exits in New valleys jwithin the set of possible next valleys N(i)

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Structure of a Decision Block

BLOCK “A”

e(A)entry states p(A)

post-exist states

Decision A

Modifiers uA

Fuzzy Goal Image gA+

g0, g1, w, r*

Nets: JA-, gA-(i)Net: JA+

Internal Nets: JA0 Critic (local U) JAI Critic (p(A) result) Local Action or Decision Net STOCHASTIC p(A) Predictor

Info From

HigherBlocks

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Conventional Encoder/Decoder Conventional Encoder/Decoder (“PCA”)(“PCA”)

Input Vector X Encoder

HiddenLayer

RDecoder

Predictionof XERROR

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Input X

EncoderInitial

R Decoder

Predictionof X

MutualInformation

Stochastic ED (See HIC Ch. 13)

Noise GeneratorWith Adaptive Weights

SimulatedR

Full Design Also Does the Dynamics Right

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CEREBRAL CORTEX

Layers I to IIILayer IV: Receives Inputs

Layer V: Output Decisions/Options

Layer VI: Prediction/State Output

BASALGANGLIA

(Engage Decision)

THALAMUS

BRAIN STEM AND CEREBELLUM

MUSCLESSee E.L. White,Cortical Circuits...