FUNDAMENTALS OF DISTRIBUTION AND

TRANSMISSION GRIDS

RALPH MASSIELLO

JANUARY 2018

OUTLINE

• The Electric Power System

• Grid Operations

• Towards the Future Grid

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THE ELECTRIC POWER SYSTEM

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• The Electric Power System is a network of electrical components that supply, transfer and use electric power.

• The electric power system can be broadly divided into distinct functions

• Generation - energy supply by a producer

• Transmission - energy transfer from supplier to load center

• Substation - energy conversion from transmission voltage to distribution voltage

• Distribution - energy transfer from load center to the customer

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Home/BusinessDistribution Transmission & Substation

Generating Station

Flow of Energy

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TRANSMISSION VS. DISTRIBUTION• Long distance transport of electricity• Typical transmission voltages are

operated upwards of 125KV (high voltage)

• Transmission lines can be overhead or underground, where underground is typically found in areas like large cities

• Distribution feeders operate at medium voltage (1KV-35KV)

• Can be overhead or underground• Distribution systems typically have 1-3

wires or phases (A, B ,C ) and a neutral. • Distribution transformers step the

voltage down to 120 or 240 volts for residential customers and to 480 volts for commercial customers

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INTRODUCTION TO DISTRIBUTION OPERATIONS The Distribution System is a complex system that requires constant 24/7 monitoring and operations. Frequency of events and configuration changes in distribution system is orders of magnitude higher than transmission systems.

Planning Operations

▪ Manage System Risk: Planning & Real-Time ▪ Arrange Outage Requests▪ Monitor Line & Loading Limitations▪ Monitor System Integrity▪ Write Switching Requests

Operations

▪ Manage 24x7 operations ▪ Monitor System Conditions and Events▪ Real-time Operations▪ Maintain System Configuration▪ Restoration of Service▪ Facilitate Planned and Emergent Work▪ Adhering to Zone of Protection▪ Dispatch resources

Emergency Preparedness

▪ Handle significant events, manage and support emergency incidents, mitigate threats to public safety, employees, the environment, and to ensure delivery of service

EVOLVING DISTRIBUTION OPERATIONS

• Gaining visibility, measurement and monitoring of DER production behind the meter for real-time distribution analyses

• Integrated distribution reliability, automation and protection are critical for effective distribution planning and operation, including predictive reliability modeling to identify optimal locations of distributed technologies

• Planning for DER outages/failure to perform

• More circuit configuration options in operations with DER

• Fault location isolation and service restoration (FLISR) capabilities and integration in operations

• Dynamic protection adjustments and dynamic islanding capabilities

• The ability to control DER power and VAR production for grid support

• Advanced Distribution Management System (ADMS) applications and the ability to select distribution protection settings for the ADMS

DOE REFERENCE MODEL – FOR THE FUTURE GRID

Merchant DG

DC/AC

Inverter

OLTC OLTC

OLTC OLTC

Distribution

Operations Center

Primary Distribution Substation

Primary Distribution Substation

Fast

stabilization

Recloser

Recloser

Distribution

Transformers

EV Charging Stations

Utility

Bulk Storage

DC/AC

Inverter

RPower Flow

ControllerR

DC/AC

Inverter

Merchant DG

Distribution

Transformer

Distribution

TransformerDistribution

Transformer

Distribution

Transformer

Line

Sensor

Line

Sensor

Line

SensorLine

Sensor

Transactive

Commercial

Building

Prosumer DG

Prosumer DG

Merchant DG

Merchant DG

Merchant DG

Line

Sensor

Power Flow

Controller

Power Flow

Controller

V/VAr

Control

Agent

V/VAr

Control

Agent V/VAr

Control

Agent

Voltage

Control

Agent

Merchant Storage

The “Energy Bank/

Warehouse”

Ctrl

G

Ctrl

VER

Tertiary

CtrlVolt/Var

regulation

Storage

Secondary

Ctrl

LoadDR

Sync/PCC Microgrid

To other

feeder loads

Shunt

Capacitor

Distribution

Transformer

DER

AggregatorDER

AggregatorDER

Aggregator