1

Thinking About the Whole Grid:

Grid Architecture

2

The Word “Architecture” Is Used Many Ways• House or building layouts• Master plans• Organization models

device like an integrated circuit chip company internal arrangement

• Block diagrams• High level (“logical”) design views of IT systems• System designs or implementations• Other abstractions like layer models

We need to be clear on what we mean by grid architecture.

3

Purposes:o Identify legacy constraints

o Remove barriers and refine essential limits

o Help manage complexity (and therefore risk)

o Support early stage modernization processes

o Identify gaps in structure, technology

o Assist communication among stakeholders

o Define platforms

o Inform interfaces and interoperability

Architecture An abstract depiction of a system,

consisting of black box components, structure, and externally visible properties

System Architecture

Architecture is not design.

4

Elements of System Architecture: Components

• Abstract components– The individual parts, viewed as

“black boxes”

– Example: storage battery• At this level we do not specify

how the battery works• Care about externally visible

characteristics like storage capacity, max power rating

– But thoroughly grounded in reality • no “magic” boxes, miracles, or

anti-gravitySource: Sidney Harris

5

Elements of System Architecture: Structure• Abstract components

– The individual parts, viewed as “black boxes”– But thoroughly grounded in reality (no “magic” boxes)

• Structures– The overall shape of the system and how components

interact– Any complex system has multiple structures, requiring

multiple views– No real architecture can be represented in a single diagram

6

System Complexity and Electric Grids

MediumComplexity

HighComplexity

Power systems are off the chart…

LowComplexity

Complexity is the hidden bear in the room when dealing with grid futures.

7

Why is the Grid Ultra-Large-Scale Complex?• The grid is

comprised of many already complex structures

• These structures are interconnected and interact in complex ways

• This results in an explosion of complexity.

8

Purposes:o Identify legacy constraints

o Remove barriers and refine essential limits

o Help manage complexity (and therefore risk)

o Support early stage modernization processes

o Identify gaps in structure, technology

o Assist communication among stakeholders

o Define platforms

o Inform interfaces and interoperability

Architecture An abstract depiction of a system,

consisting of black box components, structure, and externally visible properties

System ArchitectureGrid Architecture is the application of system architecture, network theory, and control theory to the electric power grid.

A grid architecture is the highest level description of the complete grid, and is a key tool to help understand and define the many complex interactions that exist in present and future grids.

9

Grid Architecture Focuses on Structure• Because we have inherited

much legacy grid structure, new capabilities and improved characteristics can require understanding of existing grid structure and potential changes to grid structure

• Determining minimal changes to relieve structural constraints is a key grid architecture problem • Get the structure right and all the pieces fit into place

neatly, all the downstream decisions are simplified, and investments are future-proofed

• Get the structure wrong and integration is costly and inefficient, investments are stranded, and benefits realization is limited

10

Values of Good Structure

• Good structure has well-understood properties that can be relied upon for grid design.

• Proper structure creates intrinsic grid characteristics that bolster resilience, capability, and affordability and help safeguard investments by limiting change effects.

• Well-planned grid structure simplifies downstream decisions and frees up architects and engineers working on individual components or systems to employ creativity with assurance that unintended consequences will not crop up to hamper or even invalidate their work.

11

Grid Architecture Methods• Clarity of definitions• Focus on structure• Uses foundational

principles• Driven by:

• User requirements• Emerging trends• Public policy/regulation

• Agnostic to:• Products and services• Business models• Hype cycles

• Reference architectures are instructive, not prescriptive

Manage ComplexityProduce Insight

Customer expectations

Emerging trends

Policy/Reg

Grid Present State

Systemic Issues

Arch Principles

Arch Dev

Architecture

Objectives

12

You Do Not Have to be an Architect to Use the Results of Grid Architecture

Grid Architecture supports a wide range of stakeholders, including:

Consumers and

Prosumers

Public Policy Makers,

Regulators

UtilityExecutives

Engineers and Grid

Operators

Grid ProductVendors Researchers

User Domain Provider Domain

Applying Grid Architecture

14

A Few Core Grid Architecture Principles

• Understanding structure and structural context• Structure Problems: Bypass Hidden coupling Gapping

• Modularity and Decoupling• Layering and Platforms• Buffering• Layered Decomposition

14

Structure Models: ERCOT

15

FederalLegislature

PUCT

Federal Hydro Generators

Public Hydro Generators

C&I CustomersResidential Customers

Independent Market Monitor

Power Market Administration

FERC

Texas Legislature

Entity Class

only 1zero or 1zero or more1 or more

KeyAggregators

A Brelation>

A acts on or for B

A B<relation

B acts on or for A

A B<relation>

bilateral relation

Energy and services

Control and coordination

State regulation

Federal regulation

Retail

Market interaction

Reliability coordination

NERC Texas RE

Neighboring Grids with DC

Ties

Bulk Power Marketers, Arbitragers

Merchant Generators

Distributed Generator

Other Transmission

Operators

Competitive Retail Electric

Provider

Distribution Provider

Transmission Service Provider

Balancing Authority

Reliability Coordinator

Transmission Operator

Wholesale Market

Operator

ERCOT

1. ERCOT fulfills other NERC functions not indicated in this diagram2. Potomac Economics is the current Independent Market Monitor.3. The dotted lines connecting entities in the retail layer show the relations in the absence of any REP4. TSP approves or denies transmission service requests from purchasing-selling entities, generator owners and load-serving entities (not shown in diagram)5. All market participants are monitored by Potomac Economics, and they have to be notified any changes in ownership and structure (not shown in diagram)6. Wholesale storage load is part of the merchant generators.

sets policy for >

< approval and oversight

< regulates

regu

late

s ope

ratio

n >

licen

ses &

insp

ects

>

delegates development & enforcement of standards >

oversight on compliance >

enacts policy through >

< de

lega

tes

relia

bilit

y m

onito

ring

to

oversees and regulates >

< reports on competitive performance &

operational efficiency

monitors market participants & rules >

< provides reports on reliability to

compliance enforcement >

< re

gula

tes

oversight on compliance >

mon

itors

& d

irect

s >

operates distribution facilities & provides services for >

< sells retail electricity to

< co

ordi

nate

s op

erat

ions

>

< ba

lanc

ing

& co

ntro

l

reliability alerts >

< re

gula

tes

< coordinates operations

oversight on compliance >

< interchange power >

regulates >

< DC interchange services

<coordinate power exchange>

< DC interchange services

Resource Entity

Retail Market Operator

provides customer switch information >

prov

ides

met

er re

ads &

cu

stom

er c

onne

ctio

n >

Opt In Entity

serv

es c

usto

mer

s vi

a >

owns & operates >

Non Opt In Entity

< pr

ovid

es b

ulk

pow

er to

Qualified Scheduling

Entity< co

ordi

nate

tran

sfer

ca

pabi

litie

s

< co

ordi

nate

s op

erat

ions

< pr

ovid

e bu

lk p

ower

se

rvic

es to

< ba

lanc

ing

& co

ntro

l

balancing & control >

< directs system restoration

is a type of >

< balancing & control

repr

esen

ts >

< sells retail electricity to

Load Serving Entity

< re

pres

ents

repr

esen

ts >transacts with >

< represents

< re

pres

ents Bilateral

Market

can transact in >

Structural Models

16

ICE

bilateral markets(OTC)

System Operator(ISO or RTO)

operates >

LSEs(lncl bundled utils and

indep retailers)

bid to sell into >

< buy from

organizedwholesale markets

(FERC regulated)

operates >

bid to sell into >

Merchant & utility gen

DER/DER aggregators

sells into >

sell

into

>

Merchant & utility ancillary services

bid to sell into >

< bu

ys fr

om

brokers< transact > < buy through

resellers< bid to buy from

buy from >

TerminologyBA – Balancing AuthorityCFTC – Commodity Futures Trading CommissionDER – Distributed Energy ResourceICE – Intercontinental ExchangeIPP – Independent Power ProducerISO – Independent System OperatorLSE – Load Serving EntityNYMEX – New York Mercantile ExchangeOTC - Over the CounterPPA – Power Purchase AgreementRTO – Regional Transmission Organization

One; any particular

One and only one

Zero or more; optionally many

One or more; at least one

Cardinality Symbol Key

BA2

< operates

bid into >

bid

into

>Exchanges(CFTC regulated)

NYMEXoperates > < operates

hedg

e vi

a >

BA

< bid to buy from

Retail markets1

consumers

< bu

y vi

a

Auctions(capacity, ftr)

< buy from

< sell via

brokers

sell

thro

ugh

>

< transact >

PPAIPP owns > utility< buys electricity via

PPADGen Owner

owns > end users< buy electricity via

Special Case

hedg

e vi

a >

Notes1 Retail markets are not organized central markets. They are ad hoc bilateral arrangements.2 Some ISO/RTOs operate balance markets for neighboring BAs.

17

Sensor-Communications Network Layers:Reduce Dependency & Brittleness

Disjoint Sensor Sets

System 2

Application 1

Data Exchange via Interop Standards

System 3

Application 2

Application 3

System 1

SCADAData Coll Engine Virt Platform

CommunicationNetworks

Siloed ApplicationSystems

AMI DMS DERMS

Structure Transformation

Brittle & Expensive Resilient & Future-proofed

18

An Example Grid Architecture Method

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Definition: The Grid Coordination Problem• Grid coordination is the systematic operational alignment of

utility and non-utility assets to provide electricity delivery• Coordination was not a well recognized issue for electric

distribution until fairly recently Some forms have been around a long time

o C&I DRo Bulk gen in deregulated industry segments

• The motivation for the present level of interest is the rise of three things: Distribution connected DG and DS Flexibly controllable loads Ubiquitous connectivity

Coordination is an issue because many of these resources are not owned by the utility and often may not be controlled directly.

20

Structural Problems to Avoid-1• Hidden Coupling

21

Structural Problems to Avoid-2

• Tier Bypassing• Coordination Gapping

Not So Simple in Real Situations

22

Federal Regulators

Federal Legislature

State regulatorState Legislature

WECC Peak RC

NPCC

BPA Power Marketing

Administration

Transmission (TO, TOP, TSP,

TP)

Balancing Authority (BA)

Federal Dams & Hydro

Generators

Public Hydro Generators Merchant IPPs Energy

Northwest

Other Balancing Authorities

Other Transmission

Providers

Public UtilitiesInvestor-Owned Utilities

Distribution Service Provider

Public Utility Governance

Direct Service Industries

C&I Customers Residential Customers

DER/DR Aggregators

Energy Imbalance

Market

CAISO

directs >

directs >

< directs

< ov

ersig

ht o

n co

mpl

ianc

e

regulates >

regu

late

s >

regulates >

crea

ted

>

sets priorities & recommends >

sets priorities & recommends >

coor

dina

tes

relia

bilit

y >

mar

kets

pow

er

from

>

< se

lls fi

rm &

seco

ndar

y no

nfirm

pow

er to

disp

atch

, con

trol

ge

nera

tion

><

coor

dina

te

pow

er fl

ow >

< di

spat

ch, c

ontr

ol

< in

terc

hang

e po

wer

>disp

atch

, con

trol

gen

erat

ion

>

< tr

ansp

ort b

ulk

pow

er to

(bila

tera

l co

ntra

cts)

enforces compliance >

< tr

ansp

ort b

ulk

pow

er

(bila

tera

l con

trac

ts)

< se

ll re

tail

elec

tric

ity

< di

spat

ch D

ER/D

R<

deliv

er p

ower

to

buy/

sell

reta

il el

ectr

icity

>

< di

spat

ch

DER/

DR

sets targets & reviews performance >

< re

lay

disp

atch

DE

R/DR

< se

ll re

tail

elec

tric

ity to

< op

erat

es

< tr

ansp

ort b

ulk

pow

er to

(B

ilate

ral c

ontr

acts

)

dispatch DER/DR >

< se

ll EI

M in

crem

enta

l pow

er

< se

lls p

ower

to

< se

ll in

dust

rial f

irm &

se

cond

ary

nonf

irm p

ower

to

sets policies and objectives >

Wholesale Power

Aggregators

Exchange

< po

wer

trad

ing

>

< po

wer

trad

ing

><

who

lesa

le

pow

er tr

adin

g >

Bonneville Power Administration (BPA)

Federal Columbia River Power

System

< se

ts p

riorit

ies &

co

nstr

aint

s

regulates >

sell EIM incremental power >

may

be

regi

ster

ed a

s EIM

en

tity

>

coor

dina

te

oper

atio

ns >

< co

ordi

nate

EIM

tran

sfer

s with

EIM

ent

ity B

A

• Want structure to be derived rigorously• Need a distributed form with knowable properties• Here we are not interested in a specific solution

but rather a class of solutions• We wish to extract essential structure by

understanding the problem class

Structural Basis for System Coordination

Mathematical Basis from Optimization Theory

Laminar CoordinationFramework

11

24

Network Utility Maximization viaLayering for Optimization Decomposition

• Well-known in optimization theory for solving problems with highly coupled constraints

• We will use the math to induce a coordination structure

Essential Laminar Coordination Structure

• Multi-layer structure

• “Vertical” chain of coordination nodes: scalable message flow

• Core repeating building block: coordination domain

• Scalable• Distributed

Mapping to the Grid

• Decomposition can be applied to as many levels as needed

• Known structural properties

• Accommodates multiple coordination approaches

• Boundary deference• Multi-level objectives

& constraint fusion– Local objectives &

constraints– Global coordination

• Proportional buildability

Adjusting Coordination Structure

TSO/BA

TransCo Merchant Gen

Cust Sites

Merchant DER

DSO

Microgrids

TransCo Merchant Gen

Cust Sites

DistCo

Microgrids

TSO/BA

Merchant DER

27

28

This Approach Leads to General Principles

• Scalable multi-layer form• Local selfish optimization inside global

coordination• Allows mixed coordination signal models:

– Allocations (control)– Prices (market-like methods)

• Proportional buildability

29

Grid Architecture Informs the TDC Coordination Problem in Useful Ways

• Scalability, granularity• Functional flexibility• Distribution platforms• Cyber security

• Roles and Responsibilities

• Grid observability • Distributed control• Coordination structure

30

Thank you

See Grid Architecture website at: https://gridarchitecture.pnnl.gov/