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

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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

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Bella Coola Microgrid

Benefits: Reduced use of fossil fuel based generation

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

13 10/10/2013

GE Products & Solutions For Microgrids

GE Microgrid Offering a System Solution

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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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Screen Shots from Twentynine Palms

U90Plus

Cimplicity