advances in control systems and grid connection switchgear ... · low voltage ac switchgear • may...

© 2017 Eaton. All Rights Reserved..

Advances in control systems and grid connection switchgear for

energy storage and microgrid projects

John Vernacchia – segment manager, alternative energy

2nd IBESA U.S. Storage Day at SPI

September 10, 2017

© 2017 Eaton. All Rights Reserved.. 2

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U.S. energy storage market snapshot - SEPA


Grid connected

switchgear

Energy storage

system controller


Beyond the battery and inverters: Utility-scale energy storage system elements

• DC switching and protection

• DC bus and/or flex bus

• Cable tray for battery cables

• Medium-voltage transformers

• AC grid interconnection switchgear

• Energy storage system controller

Intelligent control and protection solutions are essential to supporting large-scale energy storage systems: enabling broader new functionality, while enhancing safety and reliability.


DC switching and protection is not trivial

• DC switches provide a means to disconnect the battery containers or racks

• DC fuses provide short circuit current interruption protection

• Battery system short circuit current requirements are much higher than solar systems!

• Battery systems: 30 to 50 kA typical

• Solar systems: 5 to 10 kA typical

• Battery and solar applications challenging

standards and component performance:

• Battery system DC bus: 1500 Vdc and 50 kA;

some request up to 100 kA

• Solar system AC bus: 800 Vac 35 kA


Inverter architecture dictates AC grid connection

Inverter architecture Larger kW (central) Smaller kW (distributed)

Typical inverter characteristics • 500 to 2500 kW

• Typically outdoor rated

• Pad or skid mounted

• Air or liquid cooling

• 50 to 250 kW

• Typically indoor rated

• Rack or floor mounted

• Air cooling

Low voltage AC switchgear • May not be required

• LV switchboards aggregate

connections from smaller

inverters

Medium voltage transformer • Steps up inverter output voltage

to grid voltage

• 480 Vac to 35,000 Vac

• Steps up inverter output voltage

to grid voltage

• 480 Vac to 35,000 Vac

Medium voltage AC switchgear • Recloser

• Padmount

• Metal-enclosed

• Metal-clad

• Recloser

• Padmount

• Metal-enclosed

• Metal-clad


AC grid connection storage project examples

Smaller distributed

inverters

with LV switchboards

Large central inverters

with direct bus connection to

MV transformers


Energy storage project profile - System with a large kW central inverter

• Size: 2 MW / 8 MWh

• Location: California, USA

• Application: Renewable balance

• Battery type: Lithium ion

• Commissioned: December 2016

• AC grid connection content:

• Medium-voltage switchgear

• Medium-voltage liquid filled

transformer

• Low-voltage switchboard

• B-line series cable tray

• Commissioning services


Energy storage project profile - System with smaller kW distributed inverters

• Size: 37 MW

• Location: California, USA

• Application: Renewable balance


• Commissioned: December 2016

• AC grid connection content:

• Medium-voltage switchgear

• Medium-voltage liquid filled transformer

• Low-voltage switchboards



Energy storage control system

• Interface between battery vendor BMS and utility control system

• Energy storage specific applications

• frequency regulation

• renewable firming

• load shifting

• etc.

• However, it may be required to do more than just energy storage


Energy storage can be one element of a larger microgrid


Energy storage / microgrid control system

• Modular and scalable for utility energy storage

or microgrid applications

• Flexible to expand and control other forms of

Distributed Energy Resources (DER)

• Optimize renewable energy assets

• Interface to controllable loads and demand

response software

• Interface to building or utility SCADA system

• Can operate in both grid connected and

islanded modes

• Photo: operational microgrid system at Eaton’s Power System Experience

Center near Pittsburgh, PA with Power Xpert Energy Optimizer controller


Energy storage / microgrid control architecture

Fuel Cell Engine Generator Energy Storage Photovoltaic Controllable Loads

To Upstream Grid

IEC-61850

Local Controller -

Fuel Cell

To Upstream Control

Local Controller -

Gen Set

Local Controller -

Load

System Controller

PCCBreaker/Recloser

HMI

LocalController -

Energy Storage

Local Controller -

PV


System Balance

• Generation and

demand priority

management

• Fast load

shedding

• Dynamic

demand

response

• Dynamic energy

storage

management

• Protection and

fault isolation

Frequency &

voltage control

• Islanded

generator Freq.

control

• Generation-

demand

balancing

• Supporting

renewable

dynamics

• Ramp rate

control

• Ancillary services

• Energy storage

integration

Seamless

islanding

• Unintentional(Se

amless) islanding

• Fast grid-fault

detection,

isolation and

safety interlocks

• Load shedding

• Source

management

• Grid

reconnection

Lowest cost

• Utility Demand

Response

functionality

• Energy arbitrage

• TCO

optimization

• Fossil fuel

conservation

• Peak shaving

• Load shifting

• Conservative

voltage

regulation

Renewable

optimization

• Smart inverter

controls

• Energy storage

integration

• Adaptive system

to weather and

price forecast

• Renewables

maximization

option to save

fossil fuel

• Ramp rate

control

• PV curtailment

System Design

• Open Comm

standards

• SCADA &

enterprise

interface

• Modular, Pre-

engineered

templates

• Legacy asset

compatible

• Adaptable to

future asset

changes

Energy storage / microgrid control design and use cases

Black Start

• Gen source

start-up

• Sequencing

• PQ stabilization

• Load sequencing

& management

Black Start

• Safety interlock

for grid isolation

• Gen and

renewable

source start-up

• Paralleling

sources

• Power Quality

stabilization

• Load sequencing

& management


Seamless

islanding

Energy storage / microgrid design and use cases

Immediate response to grid separation

• High-speed isolation from grid

• Block inadvertent reconnection

• Microgrid source outputs change to carry internal load

• Microgrid sources regulate voltage & frequency

• Excess load is shed to maintain stability

Sustained control

•Manage sources and loads to optimize stability and meet secondary targets (maximize renewables, minimize fuel consumption, etc.)

Return to grid

•Ensure stable grid supply

•Coordinate microgrid voltage and frequency to match grid

•Supervise resynchronization

•Re-balance sources & loads to achieve grid-connected targets

Breaker

Opening

Load

voltage

Microgrid

Source

Current

Intentional Islanding

Under certain conditions (e.g. severe weather) the microgrid may be islanded intentionally

•Microgrid sources and loads varied to achieve net-zero power flow from utility

•Microgrid intentionally isolates from the grid

•Microgrid sources provide voltage and frequency control


Black Start

• Gen source

start-up

• Sequencing

• PQ stabilization

• Load sequencing

& management

Black Start


Start Microgrid from “Black” state (no sources)

• Isolate from grid

•Block inadvertent reconnection

•Loads disconnected from sources

•First source started & connected, providing stable voltage & frequency to a portion of the microgrid

• Intelligent sequencing of additional microgrid sources and loads to maintain stability

•Transition to standard islanded operation

Renewable

optimization

Renewable Optimization

•Sources within the microgrid (esp. energy storage) smooth variations in renewables

•Combined with storage and conventional generation, variable renewables become viable sources in islanded applications

•Smart inverter controls enable inverters to be used for Var / Voltage control

•Ramp rate control

•PV curtailment



Source: DOE Storage Handbook 2014

• Ancillary

services

• Demand

response

• Energy

arbitrage

• Peak shaving

• Load shifting

A variety of sources combined with intelligent source and load control provide grid-tied functionality

• Net Demand Response (combination of load shedding and generation sources)

• Net Demand Management (peak shaving, load shifting, load shedding)

• Energy cost optimization

Microgrid sources, especially energy storage, have additional use cases:


Energy storage project profile - energy storage / utility microgrid controller

• Size: 5 MW system

• Location: Oregon, USA

• Application: Utility distribution microgrid


• Commissioned: October 2012

• Grid connection content: • Medium-voltage AC switchgear

• Medium-voltage transformer

• Low-voltage AC switchboards

• Metering

• UPS

• Energy storage utility feeder microgrid

controls



Energy storage project profile - Not just North America

Amsterdam Arena

• 3 MW total / 2.8 MWh

• Powering on-site electrical distribution

feeders and utility-connected transformers

• Incorporating recycled and new batteries

Eaton collaborations in action

• Eaton xStorage Building solution

• Eaton/Nissan Li Ion battery racks

• Eaton UPS/Grid Storage inverter platform

Applications

• Frequency regulation

• Peak shaving

• Backup power for arena events


Eaton Experience Centers in Pittsburgh and Houston provide customized training


Thank you

• John Vernacchia, segment manager,

alternative energy, Eaton

• [email protected]

• Booth #3175

• www.eaton.com/energystorage

• www.eaton.com/microgrid

mailto:[email protected]

http://www.eaton.com/energystorage

http://www.eaton.com/microgrid

advances in control systems and grid connection switchgear ... · low voltage ac switchgear • may...

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