New York’s Reforming the Energy Vision (REV) initiative seeks to fundamentally transform the way electricity is distributed, generated and used across the State. Utilities are being challenged to adapt their business models and distribution infrastructure to meet these new goals. REV also presents an opportunity for utilities to provide their customers with a broader range of services that lead to a more diverse, innovative and resilient energy infrastructure. A key focus of REV is the transition to local distributed energy platforms including microgrids, which can be operated in conjunction with the grid or independently in emergencies. TRC recentlypresented an educational webinar to help New York’s utilities and other decision makers take action to plan and implement successful microgrids. This presentation covers: • Basic concepts for developing a microgrid • Differences from operating within the conventional grid • Preliminary engineering steps required • Options for generation sources The webinar recording is available at http://blog.trcsolutions.com/wp-content/uploads/2015-01-22-10.02-Planning-a-Successful-Microgrid.mp4

1. www.trcsolutions.com
Planning a Successful Microgrid
January 22, 2015
Bill Moran, Senior Electrical Engineer
Mark Lorentzen, Vice President, Energy Efficiency

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Today’s Grid
Source: http://peswiki.com/index.php/Directory:Smart_Grid

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Tomorrow’s Microgrids
Georgia Tech, Climate and Energy Policy Lab
http://www.cepl.gatech.edu/drupal/

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TRC Microgrid Team
-

5. A pioneer in groundbreaking scientific and engineering developments since
1969, TRC is a national engineering, consulting and construction management
firm that provides integrated services to three primary markets:
Energy | Environmental | Infrastructure
 Expert problem solvers
 100+ U.S. offices
London office
 3,000+ employees
 NYSE: TRR
5
Company Profile

6. TRC’s Guiding Principles
Our Mission
’
creativity, experience, integrity and dedication to deliver superior solutions to
’ f .
Our Vision
We will solve the challenges of making the Earth a better place to live –
community by community and project by project.

7. ENR Top 500 Design Firms
7
"The energy market growth is inevitable and one of
the largest sectors for capital investment. Any
design firm working and supporting that market
will have a bright future.“
Chris Vincze, CEO, TRC Companies Inc.
E32 36 TRC Cos. Inc., Lowell, Mass.
Rank
2013 2012
Firm Firm Type

8. Growth Drivers
Reliability | Power Supply | Aging Generation Assets | Regulatory
8
 Electrical Transmission, Distribution &
Substation Engineering
 Energy Efficiency, Demand Response, Renewable Energy, CHP
 Communications Engineering
Transformation

9. High-Profile Private Sector Clients
9

10. Working With All Levels of Government
10
State and Local Federal

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Speaker Highlights
Bill Moran has over 35 years' experience in
electrical power generation and distribution
with a focus on the design, construction and
operation of large campus type power
distribution systems. Bill is the lead technical
consultant supporting the development of
f ’ Microgrid Grant
and Loan Pilot Program.
He is a key member of the TRC Microgrid
Team, a multidiscipline team of experts
assembled to help clients plan, design and
build microgrids.
William Moran
Senior Electrical Engineer
TRC Companies, Inc.

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• Microgrid development – where to start
• Site selection and types of distribution
• Load management
• Generation sources
• Microgrid protection and controls
• Grounding
Overview

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• Multiple critical facilities
• Physical location – Critical Facilities and generation all within
reasonable walking distance; voltage drop and cost of
distribution feeders are considerations
• Widely spaced facilities with numerous non-critical sites
between will greatly increase cost of microgrid; separating
critical and non critical facilities require additional switching
equipment and possibly a dedicated circuit
• Are all microgrid facilities within a campus, or will power have
to cross public roads?
• What does the microgrid look like?
Microgrid Development – Site Selection

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Campus Microgrid
Typical campus system has a single owner of all facilities, and
is often served from a single utility meter.

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Lateral Island Microgrid
LEGEND
CF = CRITICAL FACILITY
NC = NON-CRITICAL FACILITY
Fed from a single utility distribution
feeder, which also feeds non-critical
facilities that are not included in
microgrid.

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Dedicated Circuit Microgrid
LEGEND
CF = CRITICAL FACILITY
NC = NON-CRITICAL FACILITY
Expensive – redundant distribution circuit to connect
critical facilities with microgrid generation.

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Meet with the utility
• Identify feeder(s) to be incorporated into microgrid
• Identify primary system voltage and grounding
method
• Identify critical facilities to be included in microgrid
• Obtain DG interconnection requirements
• Discuss system hardening and reliability
improvements
– Undergrounding, loop feeds, automatic sectionalizing
Steps to Project Development

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Loop Feed Distribution

19. Features
• Redundant circuit path to each
facility
• Protective relay functionality to
isolate system faults
• Communication with other loop
switches for coordinated
operation
• Establishes self-healing
distribution
• Minimizes outages to individual
facility
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Underground Loop Distribution Switch

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Meet with Engineering consultants – establish scope of services
• Load Study
Prerequisite: upgrade metering to provide real time demand data
(1 minute interval ideal), 12 months data preferred
On Peak: 6AM – 8PM average load
Peak load and duration of peak
Off Peak: 8PM – 6 AM average load
Identify loads that can be time-shifted to off peak
• Motor starting study
Inventory motors over 1 HP
Size of largest motor
Motors over 10 HP: consider soft start or at a minimum wye-delta
starting (mandatory for inverter based systems)
Calculate starting currents for large motors
Know expected motor operating schedule and what motors operate
concurrently
Steps to Project Development

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• Load shedding study
– Tier 1 Loads (must run, most critical)
– Tier 2 Loads – less critical, to be shed short term to
preserve spinning reserve capacity
– Tier 3 Loads – emergency load reduction to avoid blackout
• Short circuit study
– Calculate available fault current when grid connected
– Calculate available fault current when islanded
Engineering Studies

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• ANSI/IEEE standard symbols
• Point(s) of common coupling shown
• Location and type of isolation switch and circuit
breaker shown
• All protective relay functions shown
• Transformer grounding shown
• Transformer impedances shown
• Meters and metering connections shown
One-Line Electrical Diagram

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Typical One-Line

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Generation selection
• Land availability
• Environmental considerations
• Energy resources
– Wind
– Solar
– River or tidal flow
– Fossil fuels
• Effect of uncontrolled renewables (wind and solar)
de-stabilizes islanded microgrid and creates need for
energy storage
Steps to Project Development

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• Generation must match the load – exactly
– Overload= under frequency trip (0.16 seconds response time)
– High speed load shedding a necessity
• Provisions for peaks (spinning reserve)
– Normally 15-20% of operating load
– Depends on system load profile
• Surge capacity (motor starting)
– Reactive power requirements
– Voltage control
Powering a Microgrid

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Generator types
• Synchronous
– Voltage and current source
– Can supply or absorb reactive power
• Induction
– Current source only
– Requires system source of excitation voltage
– No voltage control
• Inverter
– Current source, externally commutated (UL-1741)
– Current and voltage source, self commutated
– Limited fault current
– Limited reactive power capability
Powering a Microgrid

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Generator characteristics
• Base load – slowly changing or fixed
output (slow ramp rate)
– Lean burn natural gas
– Fuel cell
– Gas turbine (large) > 5MW
– Hydro
• Peaking – rapid response to follow
system loads
– Diesel
– Rich burn natural gas
– Inverters
– Small gas turbines < 2MW
Powering a Microgrid
Fuel Cells
7 MW Gas Turbine
Diesel Generator

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Energy Storage
• Load and generation
smoothing
– Short term 0-15 minutes
– Flywheel
– Battery & inverter
• Time shifting
– Reserve energy for peaking
– Transferring PV generation to
dark hours
Powering a Microgrid
Flywheel
1 MW Battery & Inverter

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Operation when grid connected
• Frequency controlled by grid
• Voltage controlled by grid
• Reactive power (VAR) demand supplied by grid
• Distributed generation controlled to maintain desired
power output (kW)
• Higher available fault current, Utility source +
Generation
Microgrid Controls

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Islanded Operation
• Frequency must be controlled by microgrid generation
• Microgrid must be able to absorb swings in load
• Ramp rate of generators becomes an issue
• How is load shared among multiple generators?
• Isochronous vs. droop governing
• Lower available fault current (generator only)
– Will likely require different settings for protective relays
– Different short circuit coordination requirements
– Potentially greater arc-flash requirements (longer clearing
times)
Microgrid Controls

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Protection
• Grid connected
– Higher available fault currents
– Need to identify external vs. internal faults to prevent false tripping
– Fast break away from grid on external fault
– Tight control of short time frequency and voltage tripping
– Provide for low generation voltage and frequency ride through; keep
generation on line as long as possible to support grid
– Separate from utility to preserve microgrid and generation
Protection and Controls

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Protection
• Island Mode
– Lower fault currents may require separate settings
– Wider tolerances on frequency and voltage tripping of generation
– Coordinate settings with load management controls to shed Tier 2
loads before frequency degrades on overload
– Look at downstream devices, may not properly coordinate tripping
with lower fault current
Protection and Controls

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Controls
• Grid connected
– Generation dispatch – maximize economics, use historical data
– Load management – maintain preplanned load preservation scheme
using real-time data; always ready for transition to island mode
• Island Mode
– Generation dispatch
• Establish base load capacity
• Establish peaking capacity (load following) (frequency regulation)
• Start additional generation as needed
• Maintaining spinning reserve
Protection and Controls

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Controls
• Island Mode - Load management
– Shed Tier 2 (and Tier 3 if required) on transfer to island
mode
– Restore loads when sufficient generation capacity is on line
– Maintain real time list of Tier 2 loads to be shed to
preserve microgrid
– Activate load shed during system disturbance, restore
loads when able
Protection and Controls

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Controls
• Synchronization - Closed transition
– Shift generation to frequency and voltage control upon
separation from utility
– Monitor external grid voltage and frequency for return of
normal service (IEEE-1547 five minute delay of retransfer
after stabilization)
– When ready, adjust microgrid voltage and frequency to
match utility source
– Close utility tie breaker
– Transition generation to grid paralleled mode
– Shut down excess generation
Protection and Controls

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• Primary system grounding when islanded
– Delta system
• Grounding transformer
– Wye system
• Generator Grounding
– Ground fault current islanded vs. grid parallel
– Grounding resistor vs. reactor
– Generator step-up transformer – Wye-Wye?
• Ground fault currents grid connected vs. island mode
Grounding

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Microgrid Development
• Identify facilities to be served
• Consult with utility for feasibility
• Identify facility loads
• Define physical and electrical boundaries and ownership of
distribution and generation
Design
• Design interconnection and physical layout of Microgrid
• Select and locate appropriate generation sources
• Design protection system for grid parallel and island modes
• Configure load management controls
• Obtain Interconnection Agreement with host utility
Conclusion

38. Questions?
Mark Lorentzen
P: 607.330.0322 | E: MLorentzen@trcsolutions.com
Bill Moran
P: 774.235.2602 | E: WMoran@trcsolutions.com
www.trcsolutions.com