CERTS Microgrids
Tom Jahns
Professor, University of Wisconsin-Madison
LPPC Rates Roundtable
May 21, 2013
Wisconsin Energy Institute
WEI
WEI provides linkage among all organizations associated with
energy science, technology and policy work at UW-Madison
DER Technologies
Dispatchable Sources
•! Small internal combustion-engine generator
•! Small gas turbines generators
•! Microturbines
•! Fuel cells
Intermittent Sources
•! Wind turbines
•! Photovoltaic
Storage
•! Batteries, Ultra-capacitors
•! Flywheels
How do we deal with
100,000+ DER units?
Cluster Loads & DER
(interfaced to the grid using a fast switch)
•! Microgrids provide the most promising means of integrating
large amounts of distributed sources into the power grid
•! Microgrids open the door to significant system efficiency
reliability improvements
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Microgrid Drivers
Provides system approach to high penetration issues
Reduce load outages by ~ 98% (UPS like system)
Fast islanding (~1 cycle)
Provides for a stiff voltage during events (SVC)
Reduced emissions and improve energy efficiencies
Effective use of Combined Heat & Power (CHP)
No transmission and distribution losses
Facilitates demand side management
Support renewable sources
Provides higher reliability & modularity
Autonomous local control (independent of loss of central controller)
Graceful degradation
Minimize engineering errors/cost/and maximizes flexibility
Plug-and-play & peer-to-peer models
Microgrids with Fast
Controls and Communications
Isolating Device
(opens during island
mode)
Utility System
Primary Connection
(13.2 kV)
1.2 MVA
Utility System
Interface Control
(Synchronization, fault
protection, islanding
detection, etc.)
Generator
Protection
and
Control
Load
control
Heat Recovered
from ICE Units
Paralleling Bus (4.8 kV)
1.75
MVA
Gen
1.75
MVA
1.75
MVA
Gen
Gen
Issues:
0.8 MVA •! Loss of control &
communication!
•! Extensive site
engineering
•! Costly heat
Heat Distribution
distribution system.
Communication & Control
Signal Path
•! Difficult to scale
1.4 MVA
EPRI: Campus Microgrid System
6
CERTS Microgrid:
Autonomous Components
Microgrid with local
Combined Heat & Power! Microgrid + CHP!
120 kV
13.2 kV
PCC
•! Autonomous DER model (independent
of central controller)
•! Plug & Play Model (avoids extensive
site engineering, design errors & allows
placement near heat/cooling loads)
•! Units control power, frequency &
voltage using local information
Microgrid + CHP!
!
Controller
PV
CH
P
CH
P
P
V
Other loads
L
c L
L cL
L c
Storage
7
CERTS Microgrid
Frequency
Voltage
1.005 pu
Vmax
1 pu
Vref
0.995 pu
Vmin
Qlimit
Inductive
Reactive Power
Qlimit
Capacitive
Reactive power-terminal voltage droop
0.5 pu
1.0 pu
Real Power
Real power-frequency droop
•! Control of individual DGs is achieved using local information only
•! Power is balanced using power frequency droop curves
•! Voltage is controlled using reactive power droop curves
CERTS Microgrid Concept
Each DER unit is a grid-forming component (controls ac voltage and
frequency).
•! Autonomous load following
•! Insures multi-unit stability (local voltage control)
•! Autonomous load transfer from overloaded source to other sources
•! Intelligent load and source shedding
The interface switch provides for autonomous islanding and
re-synchronizing to the network (opens on IEEE1547 & power quality
events)
UW Microgrid Testbed
Utility System
Static Switch
480 V
208 V
20 yd
4 wire
Cable
Diesel
Genset
75 yd
4 wire
Cable
DG 3
480 V
25 yd
4 wire
Cable
Static Switch"
9.0 kW
Y Loads
DG 1
480 V
4.5 kW
Y Load
Inverter-Based
Microsources
9.0 kW
Y Loads
DG 2
480 V
Testbed has been used to develop robust plug-and-play control
algorithms defining CERTS Microgrid
Demonstrated at Site
(inverter-based, no communications &
no storage)
!!Autonomous load following
!!Seamless separation &
automatic re-synchronizing
with the grid
!!Autonomous load transfer
from overload source to other
sources
!!UPS-level power quality
!!Stable operation for
multi-sourced systems
AEP/CERTS
Microgrid Test Bed
3-60 kW
Sources
Loads
Static
Switch
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•!
First CERTS Compliant
CHP
Systems
First product to commercially
offer CERTs controls algorithms
for microgrid operation
•! Features:
–! Low emission NG engine
–! Operated over wide speed
range to optimize fuel
efficiency
–! 700,000 BTUh recoverable
heat
–! 82.4% (LHV) overall
efficiency
TecoGen
CERTS Microgrid
Demonstration
"! Alameda County, Santa Rita Jail
Objective
•! Demonstrate the commercial implementation
of the CERTS concept
•! Reduce peak electricity demand &
demonstrate demand response
•! Improve the security and reliability of the
power supply
•! Improve the fuel cell s performance
Equipment
•!
•!
•!
•!
•!
•!
4 MW-hr Lithium Ion battery
Two 1 MW diesel generators
Smart switch
1 MW fuel cell with CHP
1.2 MW solar on rooftops
12 kV feeder
DOE &CEC funded project
Military Microgrids
!
!
Fort Sill Energy Efficient!
Microgrid!
•!
•!
•!
•!
•!
Advanced Distribution and!
Control for Hybrid Intelligent!
Power Systems:!
•! Meshed microgrid with a reliable
wireless communication system
•! Intelligent distributed controls to
promote graceful degradation
MAXWELL Air Force Base!
•! Interconnecting two buildings
•! Demonstrate CERTS advanced controls
•! 2- existing MW gen-sets
Hybrid CERTS Microgrid
500 kW hr battery
2-200 kW NG gen-sets
30 kW PV
2.5 kW wind
Wisconsin
Energy Institute
Building
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What's next?
Coupled Microgrids
Smart Switch:
Two coupled microgrids:
•!Seamless separation
•!Automatic
re-synchronizing
•!Distribution level
•!Customer level with high Local
Reliability & CHP
Standard building
block for Smart
Distribution
17
What is Next?
Microgrid as a Grid Resource
Controller
PV
PV
Lc
L
L
CHP
CHP
Lc
Lc
Storage
•! Provides a standard building block for Smart
Distribution .
•! Dispatchable bi-directional real & reactive
power.
•! Demand side management.
•! Multiple points of electrical coupling.
•! Islands & re-synchronizes autonomously.!
•! Controller interfaces with system controllers.
and locally optimizes the microgrid operation.
•! Can have custom features
18
For Discussion
•! Can utilities and microgrids be friends?
•! Is it possible to imagine creating a “win-win”
environment in which utilities embrace DER
and microgrids?
•! Are the barriers inherent in the basic
regulated utility structure?
•! Can ratemaking improve the relationship
between utilities and microgrids?
For More Discussion….
Please contact:
Prof. T.M. Jahns
[email protected]