architectural models for distributed grid structures and ... · a grid architecture is the highest...

Architectural Models for Distributed Grid Structures and Grid Virtualization

Jeffrey D. Taft, PNNLPEAC 2020

Seattle 3 March 2020

PNNL-SA-151709

Re-Shaping of the Grid is Inevitable

source: P De Martini9

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 & Grid Architecture

Grid 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.

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

Architecture Principles

Architecture Development

Architecture

Objectives

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

• 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

Core ProblemDetermine the appropriate new structures or minimal structural changes to the grid that:

• Relieve crucial constraints on new capabilities

• Limit propagation of undesired change effects

• Strengthen desirable grid characteristics• Simplify design and implementation

decisions

AgileFlexible

ExtensibleObservable

ResilientReliable

AffordableFuture-proofed

etc.

Grid

Coordinated Storage Networks

Variable Structure Grids

Logical Energy Networks

Buffered grids

Modular grids

Virtualized grids

Distributed Coordination

LayeredPlatforms

DSOs and T/D Integration

Grid Visibility/Observability Evaluation/Optimization

Instrumented grids

Grid Architectures& Concepts

provide New Structures

that combineto form Modern Grids

Layered Decomposition&

Laminar Frameworks

Gas/Electric ConvergenceInter-structure Coordination

GMLC Reference Grid Architecture Views

Layering and Platforms

Platform is a Powerful Architectural Concept

• This is about structure: how system elements grouped, organized, and related to each other

• Distinguish common support capabilities (“foundation” or “core”) from uses or applications

8

A platform is a stable collection of components that provide fundamental or commonly-needed capabilities and services to a variable set of uses or applications through well-defined interoperable interfaces.

Some Key Properties of a Platform• Separates foundation functions from end uses (“applications”) via

layering• Provides a set of services and capabilities that are useful to many

applications• The platform is stable over time, while the applications may

change frequently• Provides isolation of changes between applications and

underlying infrastructure• May scale (adjust resources) to support variable demands from

applications• Open: third parties can freely create applications that use the

platform (needs open standard interfaces)

9The value of a platform is spread across many uses.

Layering is a Powerful Architectural Concept

• Partition structure into stacked layers• There may be two or more layers in a platform

• Layer n isolates layer n-1 from layer n+1• Logical/physical layer separation

• Classic example: communication logical/physical layer decomposition

10

n+1n

n-1

General layer decomposition

Communication logical/physical decomposition

11

Layered Structures Limit Change Impacts

Layered architectures are popular in software & network design where they are often called stacks

Layering in software is often associated with abstraction and virtualization (e.g. hypervisors for virtual machine environments)

In all such cases, a principle advantage is that a given layer isolates the layers above and the layers below from changes in each other

Platforms separate stable from transient functions

Vertical decomposition Layer re-association

Disjoint Sensor Sets

System 2

Application 1

Data Exchange via Interop Standards

System 3

Application 2

Application 3

System 1

CommunicationNetworks

Siloed ApplicationSystemsAMI DMS DERMS

Physical Infrastructure

Communication Network

R

DG

DG

Device Operations(Feeder)

Circuit Operations(Substation)

System Operations(Control Center)

Sensor Network

NetworkServices

Microvirtualizer

LegacysensorSmart

sensors

App 2

App 1

App 3

Distribution Platform

Silo-to-Layer Conversion

Sensing and Measurement Architecture for Grid Modernizationhttps://gridarchitecture.pnnl.gov/media/advanced/Sensor%20Networks%20for%20Electric%20Power%20Systems.pdf

https://gridarchitecture.pnnl.gov/media/advanced/Sensor%20Networks%20for%20Electric%20Power%20Systems.pdf

Distribution Platform Concept

18

Expanded Cyber-Physical View of Electric Distribution as a Platform

Physical

Distributed Coordination

Definitions• Decentralized System – multiple separate entities

operating independently with at most some small amount of supervision

• Distributed System – decentralized system where the parts cooperate to solve a common problem

• This implies some form of peer-to-peer interaction and communication

• Coordination is the means by which a set of decentralized elements to cooperate to solve a common problem, thus becoming a distributed system This is the essence of distributed system function

• Therefore coordination structure is a key aspect of distributed systems, distributed control, etc.

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 two things: Distribution-connected generation and storage Flexibly controllable loads

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

• 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

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

Coordination Domains & Laminar Networks

18

ISO/RTO/BAA

DSO DSO DSO

PrimaryDistributio

n Substation

PrimaryDistributio

n Substation

PrimaryDistributio

n Substation

PrimaryDistributio

n Substation

Community Solar

RDistribution Scale Storage

Prosumer DERB2G Services

SDirect Inter-DSO Power Flow

UPFC R

Prosumer DERB2G Services

Merchant Storage

Coordinator node

Laminar terminal node

Inter-domain Communication bus

Electrical connection

21

Primary Coordination Domain Structure

22

Coordinator Node

Distributed Intelligence Layering

Compute/StorageCompute/Storage Compute/

Storage

ESOprosumeraccess

IPv6 Stack

ESO NOC

Feeder Control

Local Area Section

Network Control AA SubstationDistribution Control

timingtiming timing

timin

g

timin

g

BuildingEnergy

Controller

Distribution Control CenterISO Control Center

Critical Substation

Primary Distribution Substation

VirtualizationApp Protocol Stack

Coordinator

Analytics

Coordinator

Local Area Grid Control Apps

Coordinator

Feeder/Section Control Apps

Grid Devices and Subsystems

Coord Signals

timing

Substation

PV Inverter

Analytics

Device Apps


Secondary System orPremises Control

Device

Balance Control Apps

Analytics

Asset Mgmt Apps Asset Mgmt Apps

Coordinator

Zone Control Apps

Analytics

Asset Mgmt Apps

Coordinator

Data Mgmt Tools Data Mgmt Tools

Home EV Charger

Market Apps

Coordinator

Premises Control Apps

App Mgr

Analytics/Vis Tools

SA Gateway Head

Data Mgmt Tools

Analytics/Vis Tools

SA Gateway

Data Mgmt Tools

Analytics/Vis Tools

SA Gateway

Data Mgmt Tools

Analytics/Vis ToolsTools Layer Analytics Tools

Network &Compute Layer

Apps Layer

hypervisor

Grid Data TrafficResidential

Commercial and Industrial

X2ESO Data Traffic

timin

g

timin

g

SP n

etw

ork

Aggregation

VPN

ESO

AnalyticsAnalytics

Sys Control Apps

Asset/Perf Apps

Analytics

Energy Mgmt Apps

ESO Apps

App Container

hypervisor

App Protocol Stack

timin

g

timing

Coordinator

Data Mgmt Tools

Analytics/Vis Tools

Grid Data TrafficVPN

X2ESO

Virtualization VirtualizationApp Protocol Stack


VirtualizationApp Protocol StackApp Protocol Stack

Compute/StorageCompute/Storage

timin

g

timin

g

SP n

etw

ork

DiscreteGrid

Devices& Systems

LocalEthernet

BAA Level System Zone

Meter

Connectivity Compute/Storage Software

Platform Layer

Distribution Grid Virtualization


• A LEN is a segment of a primary feeder with associated devices and loads

• Ideally, each LEN has three energy sources available to it: Fed from two primary distribution feeders Some amount of DG/DS resource internal to the LEN that is

utility controlled or coordinated

• This structure recognizes two classes of DER: Edge resources (non-utility owned) Core resources (utility owned/controlled)

LENs enable distribution grid virtualization. Layering with Laminar Coordination enables grid platforming.

LEN 5

LEN 3PFC

LEN 2R

LEN 4

LEN 1

Agg 1 Agg n

Substation A

Substation B

DER DER DER

DER

DER

R

PFC

Recloser

Power Flow Controller

Agg DER Aggregator

DO/DSO

Load

Load

LoadLoad

Load

Load

Load

DG/DS

DG/DS

DG/DS

DER

Utility core resources

Non-utility edge resources


DSO/Laminar/LEN Virtualization Composite View

DSO/DO

NetworkServices

Microvirtualizer

LegacysensorSmart

sensors

Sensor Network

Smartsensors

NetworkServices

Microvirtualizer

LegacysensorSmart

sensors


R

DG

DG


R

DG

DG


R

DG

DG

Laminar Coordination Node

LEN Perimeter

Logical Energy Network Layer

Sub-LEN Laminar Network Layer(s)

Sensor/Comms Layer

Electric Infrastructure Layer

DistributionPhysical Platform Layers

DistributionVirtual Platform Layers

Coordination Data FlowNote: DER Operators not shown.

Balancing Area

Dispatch/Schedule

Grid Virtualization• Extend the platform idea across the grid: layered decomposition• Virtualize Distribution in a manner analogous to Transmission• Obtain the operational flexibility resilience benefits of microgrid

networks without physical partitioning• Facilitate DER penetration and extraction of operational benefits to

the grid

Distribution System. Incl. Core Resources Transmission SystemsT/D Substations

Laminar Domain

Laminar Domain

Laminar Domain

Laminar Domain

Laminar Domain

Laminar Domain

Logical Energy Network


Phys

ical

Str

uctu

reVi

rtua

l Str

uctu

re

Bulk Power System DomainDistribution Domain

Loads & edge resources

Balancing Area Balancing Area Balancing Area

Phys

ical

Str

uctu

reVi

rtua

l Str

uctu

re

Trans Sys


DSO/DO System Operator

Trans Sys Trans Sys Trans Sys Trans Sys Trans Sys

Gen & storage resources

Coordination Interface

Physical Interface

Jeffrey D. Taft, [email protected]

http://gridarchitecture.pnnl.gov/

http://gridarchitecture.pnnl.gov/

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