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Communication and Control for Microgrid Optimal Energy Efficiency
Rui Zhou, Sumit Bose, Santosh Veda Oct 10th 2013 GE Global Research RPI Microgrid Workshop
1 10/10/2013
• Microgrid Characteristics
• Microgrid Optimization
• Optimal Dispatch
• Volt/VAR support
• Battery Energy Storage System
• Field Demonstration
• Future Research – DC Microgrid
Overview
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• Combination of conventional and/or renewable on/off the grid energy sources
• Energy storage system to compensate for renewable intermittency
• Communication networking of all Microgrid elements including load clusters
• Integration with Protection Controls to ensure reliable operation
A smart control system to optimize and manage generators,
energy storage and loads within the microgrid
Wind Generation Diesel or Natural Gas Generation
Microgrid Characteristics
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Optimal Dispatch The process of allocating the required load demand between the available
resources such that the cost of operation is minimized.
The optimal dispatch algorithm implements Model Predictive Control using:
Load forecasts
Renewable generation forecasts (wind, hydro, solar, bio-mass)
and Stored Energy
Time
Po
we
r 24 hr
Microgrid Optimization ModelSetpoints of Storage
Devices
Load
System Topology, Fuel Cost, Start-up/Shut-down
Costs, Isoch Margin, ...
S E T T I N G S
Setpoints of
DispatchablesDevice Status
Storage State of
Charge
Renewables Electricity Price
F O R E C A S T S
Load
Po
st-p
roc
ce
sin
g
Un
it
Pre
-pro
cc
esi
ng
U
nit
U90Plus
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Building Thermal Load Management
• Building temperature raised
by a few degrees without
compromising comfort
• Load came down almost
instantly
• Kept low for 30 minutes
• Allowed enough time to
observe any rebound effect
after restoration of load.
A sizable amount of electric load can be dropped instantly by managing
the building loads. About 10% of load rebound was observed after
restoration.
Building Load (kW)
Time
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Thermal v.s. Electrical Optimization
Higher Benefits Expected with Larger Number of Assets
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Renewable Utilization
• Take full account of renewables in the cost output • The difference in cost with and without renewables in day should be the
reflection of the renewable energy contribution
Test ConditionOptimal Cost
(%)
System running with renewables (PV) enabled 100.0%
Output from next dispatch cycle after renewables are
disabled at 6:45am (sun just coming up)104.7%
Output at 10:30pm after the full PV cycle. Peak PV during
the day was 865kW105.4%
Output from next dispatch cycle after renewables are re-
enabled at 10:30pm100.1%
Optimal cost rises without renewables. The rise in cost is close to the
energy provided by PV in a day.
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Volt/Var Control
• Minimize peak load (through conservation voltage reduction) • Minimize line power losses • Minimize number of cap bank operations • Voltage falttening • Renewable assets volt/var support
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Volt/VAr Support from PV System
1.00
1.01
1.02
1.03
1.04
1.05
7:00 AM 11:00 AM 3:00 PM 7:00 PMHour
Fe
ed
er
Vo
lta
ge
(p
u)
XV
QR
V
PV
X
V
QR
V
PV
Voltage variation is caused by the interaction of power output with system resistance
9 10/10/2013
Battery Energy Storage System
• Grid-Tied, Volt/VAR, phase imbalance, and real power injection capable to…. • Increase Power Factor of Co-Generation facility • Increase overall Solar Power Plant capacity factor, specifically
during islanded operation • Provide peak-shaving during high demand periods and reduce
peak demand charges
GE Durathon Battery Grid Tied Inverter
Features: Energy & cost optimization
Volt / VAR control
Energy storage
29 Palms Microgrid (Grid Connected)
Energy Storage Benefits Power factor of Co-gen facility Solar plant capacity factor, especially during
islanded operation
Provide peak shaving during high demand periods and reduce peak demand charges
Application specifics
10-20 MW power demand
7 MW Co-gen power plant
1 MW Photovoltaic
240 kW/ 480 kWh battery
Team: GRC, GE Digital Energy, 3rd Party
Electrical Distribution
Critical Loads
Photovoltaic Arrays
Heat
Recovery
CoGen1
Chillers
+/-
BESS
Battery
Energy
Storage HTHW
Chilled Water
Loop
AA-Sub
Bulk Grid
Boilers
PV
Joshua
Heights N-Sub
CH
EE-Sub
Fairway
Heights HQ
CHP
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Future Research – DC Microgrid • Higher energy efficiency
• Variable speed operation of generators • Higher efficiency integration of PV, batteries, fly
wheels, etc.
• Increase capacity factor of renewables with energy storage
• Lower cable losses • Lower footprint and lower cost
• Transformerless (solid state and/or high frequency transformer)
• Eliminate redundant power conversion stages • Lower cable cost
• Safer/Resilience • Faster fault detection and isolation • Better power flow control
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U90Plus Distinctive Features • Support of low-intermittent renewable power
sources operating in isoch mode
• Support of both electricity and thermal systems in a single optimization framework
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