te

, Re, Wineering

a r t i c l e i n f o

Article history:Received 27 February 2014Accepted 3 May 2014Available online 24 May 2014

Keywords:MicrogridDistributed systemOptimizing energy generationReliable power supply

a b s t r a c t

dently operated according to physical and/or economic conditions[1]. The microgrid consists of numerous autonomously power-gen-erating sources that constitute a exible and efcient infrastruc-ture [2]. From this perspective, even though some of thegenerators fail to produce electricity, it does not change the realitythat the entire generation system is a microgrid. The excess power

to supporation.

The availability and cost of fossil fuel, power quality andity issues, reliability of power supply due to unplanned grosources and loads, and natural disasters, unavailability of mcontrol facilities, aging infrastructure, mass electrication, climatechange and many other problems have been faced by todayspower system industry. One of the most practical solutions forgreen and reliable power is the microgrid. It has served the threemain goals of society, those being reliability (both physical andcyber), sustainability, and economic efciency. There are severalfactors why we need distributed generation systems, such as [36]

Corresponding author.E-mail addresses: shossain@uwm.edu (E. Hossain), kabalci@nevsehir.edu.tr

(E. Kabalci), bayindir@gazi.edu.tr (R. Bayindir), perez@uwm.edu (R. Perez).

Energy Conversion and Management 86 (2014) 132153

Contents lists availab

Energy Conversion

seacts as a single controllable entity and in a synchronized way withthe conventional utility grid, but can be disconnected and indepen-

to/from utility, integration of renewable assetswithout utility presence and high level of automhttp://dx.doi.org/10.1016/j.enconman.2014.05.0120196-8904/ 2014 Elsevier Ltd. All rights reserved.t loads

stabil-wn upodern1. Introduction

The denition of the microgrid is a localized group of electric-ity sources and loads that it normally operates connected to, that

of a distributed system is evaluated by selling to the utility grid, orit can be stored in a storage system. The peak power of the micro-grid can range from a few kilowatts to megawatts. There are sev-eral features of the typical microgrid, such as seamless transitionThis paper deals with the recent evolution of microgrids being used around the world in real lifeapplications as well as laboratory application for research. This study is intended to introduce the subjectby reviewing the components level, structure and types of microgrid applications installed as a plant ormodeled as a simulation environment. The paper also presents a survey regarding published papers onwhy the microgrid is required, and what the components and control systems are which constitute theactual microgrid studies. It leads the researcher to see the microgrid in terms of the actual bigger pictureof today and creates a new outlook about the potential developments. Additionally, comparison ofmicrogrids in various regions based on several parameters allows researchers to dene the requiredcriteria and features of a special microgrid that is chosen for a particular scenario. The authors of thispaper also tabulated all the necessary information about microgrids, and proposed a standard microgridfor better power quality and optimizing energy generation. Consequently, it is focused on inadequateknowledge and technology gaps in the power system eld with regards to the future, and it is this whichhas been illustrated for the reader.The existing microgrid testbeds all around the world have been studied and analyzed and several of

them are explained as an example in this study. Later, those investigated distribution systems are clas-sied based on region (North America, Europe and Asia) and, as presented in literature, a signicantamount of deviation has been found. Several tabulated data sheets have been used to compare and con-trast the existing test systems. This research has been concluded with worthy ndings and potential areasof research that would enhance the current distributed network as well as introduce microgrid testbedscomprehensively, and aid designers in optimizing green distributed system efciency for a reliable powersupply.

2014 Elsevier Ltd. All rights reserved.Microgrid testbeds around the world: Sta

Eklas Hossain a, Ersan Kabalci b, Ramazan Bayindir c,aUniversity of WisconsinMilwaukee, Department of Mechanical Engineering, MilwaukebNevsehir University, Faculty of Engineering, Department of Electrical & Electronics EngcGazi University, Faculty of Engineering, Department of Electrical & Electronics Enginee

journal homepage: www.elof art

onald Perez a

I 53211, USAring, Nevsehir, Turkey, 06500 Ankara, Turkey

le at ScienceDirect

and Management

vier .com/locate /enconman

i. If every user (building/company/hospital/market) thinksabout reliable power and keeps own generation/battery/die-sel engine as a backup, then that is the most expensivepower system. In a microgrid system, we can get rid of thosebackup systems because the user does not have to think ofthe feeding load during a critical time.

ii. We can save a billion dollars if we can manage a few hun-dred summer peak hours by shifting or eliminating loads.

iii. So, reliability is a very good justication for selling microgr-

This system is typically used only in crowded, high power requir-ing municipal or downtown areas because of excessive expenses.In current microgrid research, it is found that mostly either radialor mesh distribution systems are used [1216].

Researchers all over the world are making huge efforts to studymicrogrids and to construct testbeds and demonstration sites,while the classication of microgrids and relevant key technologiesneed to be addressed. In this paper, we divide microgrids into threetypes: facility microgrids, remote microgrids, and utility microgr-

far. Microgrids are generally line frequency utility grids. The DERsare connected in a common bus in the microgrid. Prior to the use of

E. Hossain et al. / Energy Conversion and Management 86 (2014) 132153 133ids. It could also be justied for economic reasons (i.e. Wes-tern US). For sustainability, there is not much to compelusers in the US, but there is in China, where environmentalissues are very important.

iv. Microgrids could solve the energy crisis. It is energy secu-rity to the power industry.

v. Transmission losses get highly reduced.vi. The microgrid allows one to decrease overall costs and emis-

sions without requiring any change in daily lifestyles.vii. Critical loads can be supplied in a reliable and highly ef-

cient way by microgridsviii. In light of increasing cyber threats, it solves the cyber secu-

rity problem.ix. Viable for regions with underdeveloped transmission infra-

structures, for example remote villages, islands

The design of electrical power distribution systems has beenclassied in three ways: Radial distribution system, Mesh/Loopdistribution system, and Network distribution system. The prosand cons of the distribution systems are important to know inorder to comment on microgrid applications and source varieties.In practice, the common application is done with a combinationof those three systems. Although it is the most inexpensive distri-bution system to construct, the radial system is extensively issuedin populated areas. It involves just one power source for a cluster ofclients as shown in Fig. 1. Since all the consumers are connected toa unied source, any failure which occurs in the power line willcause a blackout [7,8].

The mesh system, as an alternative to the radial, creates a dis-tribution system that crosses all over the consumer area and endsat the generation sight. By placing switch breakers in proper sec-tions, the power can be supplied to the consumers in a bidirec-tional structure. In case of any fault occurring in one of thegenerators, the breakers are automatically switched and the powerow is sustained by service. This opportunity makes the mesh bet-ter than the radial system for microgrid applications. During powerfailures which occur due to a line fault, the utility should nd thedefective area and switch around it to restore facility with a min-imum number of consumer interruptions. Since the mesh systemrequires additional switches, conductors, and breakers, it is moreexpensive to construct compared to the radial. However, itprovides more robust distribution systems [911].

Network systems are the most sophisticated and interlockingmesh systems. Any consumer can be supplied from few power sup-plies and it surely adds a huge advantage in terms of reliability.Fig. 1. Electrical power dDC current being in demand from DERs, a conversion is required tomake it AC supply by using an electronic power inverter.

Using a HFAC transmission line in a microgrid is a novel conceptthat is still at the developing phase. In a HFAC microgrid, the DERsare coupled to a common bus. The electronic power devices con-vert the frequency of the generated electricity to 500/1000 Hz ACand transmit to the load side where it is again converted to 50/60 Hz AC by using an AC/AC converter [23,24]. The load is con-nected to the distribution line, which can assure an effective inter-action between the microgrid and distribution network. The higherordered harmonics can be easily ltered at the higher frequency,and the PQ problems are solved this way. However, power lossincreases due to the increase of line reactance are one of the maindrawbacks of HFAC [25].ids, based on their respective integration levels into the power util-ity grid, impact on main utility, their different responsibilities,application areas and relevant key technologies, as shown inTable 1. Facility microgrid and utility microgrids have utility con-nections modes but remote microgrids do not have that choice.The remote microgrids span geographically a larger area comparedto the facility and utility microgrids. The plant microgrid can pur-sue the operation in a planned or an unplanned island mode andthe sources, loads, network parameters, and control topologiesvary in each and every microgrid. The classication of microgridbased on application has also been visualized in Fig. 2, where per-centages of microgrid application and capacity for 2012 are shown[1719,25]. Moreover, a detailed study of various microgrid typeshas been illustrated in Table 1.

2. Distribution system

Three different type of distribution networks exist.

(a) Direct current line.(b) 60/50 Hz alternative current line frequency.(c) High frequency alternating current (HFAC) [7,20].

Distributed energy resources typically produce a direct currentwhich is insignicant concerning power quality; that is whyresearch has placed more stress on the DC distribution system[4,21,22]. However, most of the loads are operated in an AC sys-tem; therefore, DC distribution systems may not be popular soistribution system.

Om

Inunis

on isolated developing countries

IsM

G

andutilities electricationUtility

microgridHigh level Massive

impactonutilities

For support ofpowersystems

Mainly found in Japan,Europe, China whererenewable energy israpidly developingTable 1Detail classication of microgrid.

Classication of Microgrid

Classication Integratedlevel

Utilitiesimpact

Responsibility Application area

Facilitymicrogrid

Middlelevel

Littleimpactonutilities

Forcomplementmostly forvital systems

Mainly found in NorthAmerica specially forIndustry/Institutionapplication wheretechnology is matured

Remotemicrogrid

Low level Noimpact

Independentsystem for

Mainly found indistant areas, Islands,

134 E. Hossain et al. / Energy Conversion2.1. Distributed generation technology

Several types of distributed generation technologies have beenused in microgrid systems. Some of them are renewable and therest is fossil distributed generation. A complete study on DG tech-nology has been given in Table 2 and Table 3. From the tablesresearchers can gure out which technology should be used fortheir design system and why they ought to pick up those technol-ogies. With the help of tabulated sheets we can also analyze ourdesign system performance as well as perform a costbenet anal-ysis. Hence, the maximum efciency can be extracted with thepossibility of generating entirely green energy. Putting greenenergy into power will reduce our environmental hazards, andoffers a reliable power source for the community.

2.2. AC microgrid systems

The majority of the electric loads since last century have beenoperated with AC power. So, the standard choice for commercialpower systems is ultimately an AC distribution system [16,26].The long-distance capability of AC power, its ability to easilytransform into various levels of output for different applications,and its natural characteristic inherited from the fossil fuel drivenrotating machine, give AC power network superiority. Nowadays,researchers have focused on renewable-based distribution sys-tems and various communities have implemented it; addition-ally a huge study has been going on since last decade onoperating feasibility. Commonly, an AC microgrid system is con-nected with a medium voltage distribution line at the point of

Fig. 2. Classicatioperationalode

Geographicallyspan

Powerquality

Remarks

tentional orintentionalland mode

2 miles High Making great use of renewableenergy, increasing energyefciency, reducing pollution,greenhouse gas emissions & highpower quality reliability forsensitive loads as well to singlebusiness-entity

landedode only

30 miles Relaxed Mostly decentralized control &maximum power use is limited forthe customers

rid tie mode 15 miles Medium Providing high power quality &reliability to sensitive local loads,contributing to utility stability &robustness as well

Management 86 (2014) 132153PCC. The distributed generations, storage devices and loads areattached with a common bus base at the distribution networks.During the grid-tied mode, the system voltage and frequency aremaintained by utility grids while energy storage devices, non-renewable DGs and adjustable loads with control techniqueshelp to keep standard voltage and frequency level during island-ed mode.

Disadvantages of the AC microgrid:

Each distributed generation and utility grid couple has to besynchronized for the AC microgrid.

It has a huge effect on power quality; for example, inrush cur-rent is usually produced by transformers and the inductionmachine.

There is concern about three phase unbalance, such as the pho-tovoltaic system (single phase loads, single phase generators).

2.3. DC microgrid systems

In a DC microgrid, energy storage and a large percentage of thesources and the loads are interconnected through one or more DCbusses. Nonetheless, AC buses or some sort of DC to AC converterare still necessary due to the fact that some sources and loads can-not be directly connected to DC [2729]. Furthermore, as long asAC is going to be used for distribution, the DC microgrid will atsome point be connected to the AC grid. Hence, it is suggested thatin DCmicrogrids along with AC buses, they should be considered astwo parts of a mixed AC/DC microgrid, which is coupled to the ACgrid through the point of PCC.

n of microgrid.

andAdvantages of the DC microgrid:

Facilitates DC loads to operate with native power as mostmodern devices need DC power input.

Synchronization of distributed generators is not required. Ability to use distributed renewable energy sources thatnaturally generate DC, for example PV or wind.

The ability to use Class 2 NEC (National Electric Code) loads atnon-lethal voltages (e.g. 24 V).

No power factor losses because a DC system has zero frequency. In a DC microgrid, loads are free from voltage distortion, likevoltage sag, unbalanced voltage, or voltage harmonics [27].

No inverter or transformer losses because those devices are notapplicable in a DC system.

DCDC switching regulators can reach high efciencies if it isnecessary for certain loads.

Higher efciency than AC microgrids due to less conversion lossalso resulting in less thermal/heat wastage, and fewer compo-nents as well compared to AC systems.

In contrast, there are several down sides to implementing theDC microgrid in our present power system. A DC distribution net-work needs to be built in order to implement a DC microgrid.Moreover, due to the absence of a zero crossing point, it is hardto design a protection system for DC microgrid networks comparedto AC microgrid systems. Generally, high system efciency isrequired for operating DC microgrid loads [15,28].

2.4. Comparison of AC and DC microgrids

Looking back at a century when the great effect of electricitywas seen in the industry, a great competition took place withregards to power, AC or DC, known as the War of the Currents.The few important points of the argument that serve our purposesare: (1) the power generation cost in single large plants wascheaper than the cost of many distributed ones; (2) AC could travellong distances with low losses, unlike DC; (3) radiant lamps werethe majority of the load and they operated on AC or DC; and (4)semi-conductors had not yet been invented. However, now, withthe invention of Choppers and Boosters it is feasible to changethe level of DC voltages for different applications. Besides, powerindustries can mostly escape commutation problems, plus it canbe replaced by a rectier.

The DC microgrid only requires voltage stabilization, while anAC grid involves almost all the waveforms and should be con-trolled. The DC microgrids are mostly installed by using solar pan-els that enable one to make a connection to a utility grid over asingle string inverter. On the other hand, AC microgrids requiremore than one inverter to be connected to the grid. The absenceof electromagnetic interference, and easy power transfer at PCCare also assumed to be advantages of DC microgrid compared toAC. Despite these advantages of the DC microgrid, AC systemsprovide several advantages in transmission segments regardingits transformer and breaker-based control infrastructure, whereasthe DC microgrid has more advantages in terms of converter con-trol and efciency in distribution segments [2931]. A detailedstudy on AC distribution networks and DC distribution networkshas been illustrated in Table 4.

The majority of installed microgrids for experimental and oper-ational purposes have used AC distribution networks. AC voltagecan be increased and can be decreased easily by using electricaltransformers. In contrast, a signicantly complex and costly DCDC converter is required for different levels of DC voltage supplied

E. Hossain et al. / Energy Conversionfor different applications [15]. Besides, the protection system of DCdistribution is not mature enough compared to the AC system andmore research is needed prior to implementing such a protectionsystem. The suitable application of low voltage DC microgrids isfor sensitive electronic loads, telecommunication power devices,and control and protection of power systems. Since the existenceof DC microgrids is still limited and technology has not maturedenough, researchers are showing more interest in the DC microgridas a future reliable power system.

Recent trends for selecting the nature of power for distributedpower systems [17,43,44]:

Todays power industry is composed of numerous inverter-based loads and the conversion of ACDC, DCDC and DCACis required.

The renewable distribution generation naturally has DC poweroutput, for example: photovoltaic, fuel cell, variable speed windturbine, micro-turbine, etc.

Recently, several microgrids have been installed with DC-couples.

Power quality requirements are also another important aspect. DC microgrids/nanogrids have an effect on the selection of thenature of power and DC distributed power systems (DPS) aswell.

Some applications inherently require DC power, for example:telecommunication systems, DC-link for UPS systems, andseveral isolated systems too, such as avionic, automotive, andmarine.

3. Microgrid testbeds around the world

Numerous microgrids have been implemented and are func-tioning to supply power, or have been installed at the laboratorylevel to conduct research all over the world to analyze the opera-tion of microgrids in detail. Most of the experiments that are runby scientists are related to islanded or grid-tied systems to supportcommunities. Since the new concept of the microgrid is very versa-tile, the experiment conditions, usages, and the objectives havewidely varied [4,16,32,33].

3.1. Microgrid project in North America region

The Consortium for Electric Reliability Technology Solutions(CERTS) is the most renowned of U.S. microgrids. The main aimof this project was to make it easier to operate the micro-genera-tors together to feed the utility grid. As a result, three advancedconcepts given below have been developed to decrease the eldengineering work on microgrids [4].

Ensure automatic and transition between grid connected andislanded modes.

A protection method inside the microgrid during faults. A microgrid control scheme to stabilize system frequency andvoltage without communication system.

Moreover, the Georgia Institute of Technology and the Distrib-uted Energy Resources Customer Adoption Model DER-CAM atthe Berkeley Lab have simulated several software tools, for exam-ple, a microgrid analysis tool for microgrid systems. Typically, theproject has decentralized control with some sort of storage systemas shown in Table 5. The majority of distribution systems are pres-ently at the research and development (R&D) stage and the goalwas to implement policies for various microgrid types in termsof control and protection. North America is not only focused onrenewable energy generation but also focused on sustaining thereliability of power sources by integrating microgrid technology.

Management 86 (2014) 132153 135Furthermore, it is focusing on the use of decentralized control forthe regulation of distribution level voltage and frequency. A com-prehensive study on North American microgrids has been done

Table 2Summary of distributed technology.

Summary of distributed generation technologies

Fossil Renewable

Technology Small steamturbines

Gas turbines Micro-turbines

Reciprocatinginternalcombustionengines

Stirlingengines

Fuel cells-hightemperature

Fuel cells-lowtemperature

PV Smallhydro

Windonshore

Windoffshore

Geothermal Solarthermal

BasicsType of fuel Gas, coal,

biomassGas turbines gas Diesel, oil,

biofuel, gasGas, solar Gas, hydrogen Gas, hydrogen Solar Water Wind

onshoreWind Earth Earth

Capacity range (MW) 0.510+ 0.510+ 0.030.5 0.510+

andTable 3Review of distributed technology.

DGs technologies review

Technology Recip engine:diesel

Recip engine: NG

Size 30 kW6+ MW 30 kW6+ MWInstalled Cost ($/kW) 6001000 7001200Electrical Efciency (LHV) 3043% 3042%Overall Efciency 8085% 8085%Total Maintenance Costs3 ($/kWh) 0.0050.015 0.0070.020

E. Hossain et al. / Energy Conversionand tabulated in Table 5, which aids researchers to nd the neces-sary information for designing and analyzing a distribution system.Several examples of existing microgrid testbeds in North Americaare given below.

3.1.1. University of Texas at Arlington microgrid testbedThe UTA Microgrid lab comprises of three independent deputy

microgrids operating in grid tied or islanded fashion. Each deputygrid has a 24 VDC bus as well as a 120VAC-60 Hz AC bus. For typ-ical conguration, two 12 VDC lead acid batteries are coupled inseries as the primary energy storage. The batteries on each gridare recharged using devoted solar panels and wind turbines, or a

Footprint (sqft/kW) 0.220.31 0.280.37Emissions (gm/bhp-hr unless otherwise

noted)NOx: 79 CO: 0.30.7

NOx: 0.713 CO:12

http://www.distributed-generation.com/technologies.htm.

Table 4Summary on AC distribution network and DC distribution network.

Impact factors AC distribution system

Transmission ofpower over shortdistant

There is a signicant power loss in line hence AC system is le

More number of conductors requires for specic amount of potransmission [12]

Stability andsynchronization

External disturbances effect on stability, real & reactive powemanage microgrid stability independently & synchronizationDGs and utility grid is required [23,45]

Reluctance Reluctance is present in AC line

Frequency (50 Hz or60 Hz)/healthconcerns

Monitoring of AC system is required as it is uctuated continuLine inductance and switching introduces transient stability cElectromagnetic interference produces health concern

Resistance In AC system, the line resistance is highSusceptance A huge concern of charging current and over-voltage problemAnalysis The analysis of AC system require dealing with complex numbe

is toughHVDC transmission It is suitable for HVDC transmissionLong distant power

transmissionability

AC power can be transmitted over long distances

Reactive power Need to monitor reactive power continuouslySkin effect Need bigger cross sectional area conductor due to skin effect

Corona effect More Corona losses on AC line [21]Protection system Simpler, cheaper and matured protection system

Maintenance Maintenance is easy & inexpensiveTransformer Voltage level is adjustable using transformerCapacitance/

Inductance effectPower losses on lines during no load/open circuit

Telecommunicationinterference

AC system has telecommunication/wireless network interfere

Efciency Less due to too many conversionsNoise & danger More noisy and more dangerConversion losses DC to AC conversion loss is lessPeak voltage Higher (1.4 times) than nominal valueControl method Direct Power Control in AC systemsBlackout/voltage sag During blackout/voltage sag AC system is affectedVariable-speed

drivesIt is hard to obtain variable speed controlMicroturbine Combustion gas turbine Fuel cell

30400 kW 0.530+ MW 1003000 kW12001700 400900 400050001430% 2140% 3650%8085% 8090% 8085%0.0080.015 0.0040.010 0.00190.0153

Management 86 (2014) 132153 137PEM fuel cell and DC/AC inverter (manufactured by Outback PowerSystems). The programmable load is connected to each AC bus. Thegrid has Crydom solid-state relays mounted on the various busseswhich are controlled using a National Instruments Compact RIOcontrol system. The entire UTA grid is shown in Fig. 3. The perfor-mance of a microgrid is based on its ability to supply reliable andquality power to loads within the standards set out by denedspecications, such as MIL-STD-1399-300B or IEEE-STD-519. Ineach of these standards, regulations are given which specify theallowable variance in the voltage, current, and frequency. The DCmicrogrids mostly used for residential and static loads where thepower line is used as a communication medium [3,20,34,35].

0.150.35 0.020.61 0.9NOx: 950 ppm CO: 950 ppm

NOx:

s_N

sesel

Sandia National Lab Testbed, Radial/DC/Testbed PV, Wind Diesel

esel

otor

esels

esel

esel

andWashington, DCUT Arlington Testbed, Texas Radial/DC/Testbed PV, Wind, Fuel

CellDi

FIU Testbed, Florida Radial/DC/Testbed PV, Wind, FuelCell

M

Laboratory scale microgridtestbed, New Jersey

Radial/AC/Real PV No

UT Austin, Texas Radial/AC/Testbed No DiMicrogrid testbed at

Albuquerque, New MexicoRadial/AC/Real PV, Fuel Cell,

CHPGa

Utility Microgrid at LosAlamos, New Mexico

Radial/AC/Real PV No

RIT Microgrid, New York Mesh/AC/Testbed PV, Wind, FuelCell

No

Mad River Park Microgrid,Vermont

Mesh/AC/Testbed PV Di

Palmade Microgrid, California Radial/AC/Real Wind, Hydro DiTable 5Microgrid Testbed at North America.

Microgird Testbed at North America

Project Name Detail [Structure/PowerNature/Type]

DGs_Renewable DG

CERTS Testbed, Ohio Mesh/AC/Testbed No GaUW Madison Testbed,

WisconsinRadial/AC/Testbed PV Di

University of Miami Testbed,Florida

Radial/DC/Testbed PV, Fuel Cell No

138 E. Hossain et al. / Energy Conversion3.1.2. Microgrid testbed at Albuquerque, New Mexico by ShimizuInstitute of Technology (SIT)

The Shimizu corporation was founded in 1804 for the purposeof power system project planning, designing and facility manage-ment and maintenance and renovation. It developed a microgridtestbed at Albuquerque around 2010. This SIT testbed consists ofa gas engine generator (240 kW), fuel cell (80 kW), lead acid bat-tery (50 kW/100 kW), PV (50 kW), Dummy load (100 kW) and elec-tric load of 400 kW. The facility has Building Energy ManagementSystems (BEMS), a heat source equipment controller and a powersupply equipment controller to regulate both supply and demand.This radial type distribution system serves residential and com-mercial loads with the help of power line communication [34].The block diagram of the USA-Japan joint microgrid project testbedhas been drawn in Fig. 4.

3.1.3. British Columbia Institute of Technology microgrid testbed at BCThe British Columbia Institute of Technology (BCIT) has

designed and developed a scaled-down version of the microgridin order to present it to utility companies and researchers. Allthe participants of this project can work together to developrelated parts of the microgrid such as infrastructure, protocols,testbeds, and several other required experimental congurationsto sustain the innovations to promote the solutions and develop-ment of microgrid technology for the North American region. The1.2 MW microgrid was implemented at BCITs Main Campus inBurnaby around 2009. This campus type microgrid consists oftwo wind turbines (5 kW each), PV modules (300 kW), thermal

Hawai Hydrogen Power Park,Hawaii

Radial/DC/Testbed PV, Wind, FuelCell

No

Boston Bar-BC Hydro Radial/AC/Real Hydro DieselBoralex Plant, Qubee Radial/AC/Real No StreamVSC feeded Microgrid, Toronto Radial/AC/Testbed No Motor

Ramea wind-diesel Microgrid,NL

Mesh/AC/Real Wind Diesel

Fortis-Alberta Microgrid,Alberta

Radial/AC Real andTestbed

Wind, Hydro Noonrenewable Control Load Storage

Decentralized Residential BatteryDecentralized Static Battery

Decentralized Residential Battery

Decentralized Residential, Static Battery

, Gas Decentralized Residential, Static Battery

Centralized,Agent based

Residential, Motor Flywheel

Centralized Residential, Motor Battery

, Gas, Motor Decentralized Static, Motor FlywheelDecentralized Residential,

Commercial, MotorCapacitor

Decentralized Residential Battery

Decentralized Residential, Static,Motor

No

, Motor Decentralized Residential,Commercial, Industrial

Battery

, Gas Decentralized Residential,Commercial, Static,Motor

Capacitor

Management 86 (2014) 132153turbine (250 kW), Li-ion battery (550 kW h) and campus loads(EV charging stations, industrial load, classrooms & ofces, resi-dences) [2]. There was a command & control unit which comprisedwith the substation automation lab, MG operation control centerand MG controller. A campus-wide communication network wasalso available in this distribution system, for example, WI-Max,ISM RF, PLC, Fiber and so on, as shown in Fig. 5.

3.2. Microgrid project in Japan region

Japan has been dedicated to generating renewable energy at anoptimal level; however, this decision threatens the power qualityreputation in that region. The most common renewable distributedgeneration in Japan is wind and photovoltaic systems, and thosesources are usually of an intermittent nature which is an externalimpediment. Microgrids may be able to handle these problems,which has prompted the projects in Japan, including one of themost important implementation projects. The majority of the pro-jects are sponsored by the New Energy and Industrial TechnologyDevelopment Organization (NEDO) [4]. Very few projects haveused non-renewable distributed generations. However, the mostpopular control technique is centralized control with a storage sys-tem as shown in Table 6, and an example of a typical Japanesemicrogrid given below as well.

3.2.1. Kyoto eco-energy microgrid testbed at Kythnos Island in JapanThe Kythnos Island microgrid project, named Kyoto Eco-

Energy, has also been supported by NEDO since around 2005.

Centralized Residential, Static Battery

Decentralized Residential NoDecentralized Residential NoDecentralized Static, Motor,

ElectronicsCapacitor

Decentralized Residential Battery

Centralized Industrial No data foundabout storage

andE. Hossain et al. / Energy ConversionThe schematic diagram of the virtual type AC microgrid has beenshown in Fig. 6, where each and every distributed energy resourceand load is connected to the utility grid through a substation, and acontrol system is used to integrate these elements. This utility sup-ported microgrid is composed of gas engines with a capacity of400 kW, a 250 kW MCFC and a 100 kW lead-acid battery, two pho-tovoltaic systems and 50 kW small wind turbine. The energydemand is maintained through a microgrid and utility grid byusing remote monitoring and controlling. The centralized controlsystem and the communication system are built on several stan-dards, such as the Integrated Services Digital Network (ISDN) orAsymmetric Digital Subscriber Line (ADSL) Internet service pro-vider (ISP) for the Internet, which are the solitary connectionchoices existing in that countryside region of Japan. The mesh typeKyotango microgrid is mainly used for residential load and servesthe purpose of a utility microgrid to support the existent grid [3].

3.3. Microgrid project in European Union (EU) region

The European Union has one of the highest levels of globalwarming and climate change awareness at present. For that reason,there are certain requirements that should be met by each memberand every state within the next decade. There are numerous laws

Fig. 3. UTA microgManagement 86 (2014) 132153 139dened by the European Parliament, for example, 2001/77/EC,2003/30/EC and 2006/32/EC. These laws specify that the amountof carbon footprint emissions will be decreased by stated amountsfor every state, while increasing the amount of renewable energygeneration, hence reducing fossil energy usage and the net amountof energy consumption will be compacted by increasing energyefciency [7,42].

Consequently, there are inducements from the EU and numer-ous developments in progress among the states. Almost everyfacility in EU has used a sophisticated storage system and nonre-newable distributed generation to maintain power quality andmainly testbeds are experimenting with residential loads as shownin Table 7 with the example of the University of Seville Spainsmicrogrid at Seville.

3.3.1. Microgrid testbed in University of Seville SpainThe schematic diagram of the University of Seville microgrid is

illustrated in Fig. 7 and this domestic distribution system is pri-marily powered by a photovoltaic array. The intermittent natureof solar resources has raised reliability issues; an electrolyzer isplaced in the main power distribution line to overcome this prob-lem. During excess power generation, extra electricity is used toproduce and store hydrogen. In contrast, a fuel cell generates

rid laboratory.

and140 E. Hossain et al. / Energy Conversionelectricity by using the stored hydrogen when the system requires.A battery bank (lead acid) is also integrated in the distribution lineto maintain a xed voltage on the line, therefore it simplies theconverter design. Furthermore, the aforementioned domesticmicrogrid is connected to other neighboring grids to exchangeenergy according to demand [34].

Fig. 4. Microgrid testbed at Albuquerque,

Fig. 5. Block diagram of British ColumbiManagement 86 (2014) 132153In the microgrids Supervisory Control and Data Acquisition(SCADA) system, an M-340 programmable logic control (PLC) isinstalled as the main plant control platform. The controller is pro-vided with data acquisition cards in order to communicate withthe programmable load and power source, the plant devices andsensors. The communication between the DC/DC converters and

New Mexico by Shimizu Corporation.

a Institute of Technology microgrid.

wab

andTable 6Microgrid testbed at Japan.

Microgird Projects in Japan

Project Name Detail [Structure/PowerNature/Type]

DGs_Rene

Aichi Microgrid, Tokoname Radial/AC/Real NoKyoto eco-energy Microgrid,

Kythnos IslandMesh/AC/Real Gas

E. Hossain et al. / Energy Conversionthe PCL is accomplished retaining the Canbus communicationprotocol.

3.4. Microgrid projects in rest of the world

Asian microgrids are mostly for remote application, where theyfocus on generating whatever amount of renewable energy is avail-able for a reliable power system and later to maintain the stabilityand controllability of the systems nonrenewable DG or storagesystems it has used. The central control method is one of the favor-ite control techniques in this region with few exceptions, such as in

Hachinohe Microgrid, Hachinohe Radial/AC/Real GasCRIEPI Microgrid, Akagi Mesh/AC/Real NoSendai Microgrid, Sendai Radial/AC/Real Gas

FC-CHP based Plant, Osoka Campus/AC NoMicrogrid test facility in Yokohama,

JapanRemote/AC Gas

a: No data found.

Fig. 6. The schematic diagram ofle DGs_Nonrenewable Control Load Storage

Gas Centralized Commercial/Industrial aDiesel Centralized Residential Battery

Management 86 (2014) 132153 141China where agent-based control techniques have also been used[16,38,39]. It is common practice to have centrally controlledmicrogrids or agent-based microgrids, which has been shown indetail in Table 8 [38,39].

The unique project of Korea has been installed by the KoreanEnergy Research Institute (KERI). The microgrid test facility isequipped with a photovoltaic simulator, fuel cells, diesel genera-tors, and a wind turbine simulator along with various type of loads,storage and power quality devices. Besides, in Jeju Island a230 MW microgrid was constructed in 2009 with a wind turbineand fuel cell. For the future implementation of microgrids in the

No Centralized Commercial/Industrial BatteryDiesel Centralized Static NoDiesel, Gas Centralized Residential, Commercial,

IndustrialNo

Motor a a aNo a a Battery

Kyoto eco-energy microgrid.

andTable 7Microgrid testbed at European Union.

Microgird projects in European Union

Project name Detail [Structure/Power DGs_Renewable

142 E. Hossain et al. / Energy Conversionpower network of Korea, the Jeju Island and analogous Koreanislands are major applicants. Presently, very few remote distrib-uted power systems are available, but there is a signicant poten-tial for microgrids in the near future. Besides, the government hasalready taken initiative and has invested a huge amount of nan-cial support for researchers, and recently several microgrid

Nature/Type]

Bronsbergen Park Microgrid,Zutphen

Mesh/AC/Real PV

Am Steinweg Microgrid,Stutensee

Mesh/AC/Real PV, CHP

CESI RICERCA DER Testbed,Moneta

Radial/DC/Testbed Solar Thermal, PV,Wind, /CHP

Kythnos Island Microgrid,Kythnos Island

Radial/AC/Real PV

NTUA Microgrid, Athens Radial/AC/Testbed PV, WindDeMoTec Testbed, Kassel Mesh/AC/Testbed PV, Wind

University of ManchesterTestbed, Manchester

Radial/AC/Testbed/Real No

Benchmark low voltageMicrogrid, Athens

Radial/AC/Testbed PV, Wind, Fuel Cell

Nimbus Microgrid Testbed,Cork

Radial/AC/Testbed/Real CHP, Wind, Fuel Cell

Genoa University, Genoa Mesh/AC/Testbed PV, Wind, CHPUniversity of Nottingham

Testbed, NottinghamRadial/DC/Testbed Wind

UT Comiegne (UTC) Tesrbed,Compiegne

Radial/DC/Testbed PV, Fuel Cell

University of Seville SpainTestbed, Seville

Mesh/DC/Testbed PV, Fuel Cell

FEUP Microgrid Testbed, PortoDistrict

Radial/AC/Testbed PV, Wind, Fuel Cell

Fig. 7. Hydrogen based, domestic mDGs_Nonrenewable Control Load Storage

Management 86 (2014) 132153projects have started. The Yungngora, Kalumburu and Windorahcommunities are examples of remote microgrids. Furthermore,some energy companies are currently planning and developingmicrogrids on several islands; for example Thursday Island inQueensland and King Island in Tasmania. The most remote micro-grid project is currently going on in Western Australia where wind

No Centralized Residential Battery

No Agent based Residential Battery

Diesel Centralized Residential Flywheel,Battery

Diesel Centralized Residential Battery

No Agent based Static BatteryDiesel Agent based Residential,

Commercial, IndustrialBattery

Motor Centralized,Agent based

Static Flywheel

No Decentralized,Centralized

Residential Flywheel,Battery

No Centralized Residential Battery

Gas Decentralized Residential BatteryNo Decentralized Residential Battery

No Decentralized Motor Battery

No Decentralized Residential, Motor Battery

Diesel Centralized Static Battery

icrogrid at University of Seville.

abl

Fuel

s

nerg

andpower is the most popular renewable source as shown in Table 9.Several microgrid testbed examples have been illustrated below.

Table 8Microgrid Testbed in rest of the world.

Microgird Projects in rest of the world

Project name Detail [Structure/Power Nature/Type]

DGs_Renew

HFUT Microgrid, China Mesh/AC/Testbed PV, Wind,Hydro

Tianjin University Testbed, China Radial/AC/Testbed PV, WindTest Microgrid at IET, India Radial/AC/Testbed Fuel CellMSEDCL at Wani Area Microgrid,

IndiaMesh/AC/Real PV, Biomas

INER Microgrid Testbed, Taiwan Mesh/AC/Testbed/Real PV, WindNUAA Testbed, China Radial/AC/Testbed PV, WindQUT Microgrid Testbed, Australia Radial/DC/Testbed PV, Wind

Table 9Microgrid projects in Australia.

Microgrid detail Primary e

CSIRO, Newcastle New South Wales PVKing Island Tasmania SolarKings Canyon Northern Territory PVCoral Bay Western Australia WindBremer Bay Western Australia WindDenham Western Australia WindEsperence Western Australia WindHopetoun Western Australia WindRottnest Island Western Australia Wind

E. Hossain et al. / Energy Conversion3.4.1. NUAA microgrid testbed NUAA in ChinaThe objective for the NUAA testbed is to analyze the smooth

transition issue of microgrid systems based on the masterslavestructure; the operation principle of the phase locked control strat-egy was studied in order to be realized in digital implementation. Adevoted 100 kV A microgrid testbed was built to verify the micro-grid control strategy and it was veried by experiment. In the mas-terslave conguration based microgrid, there is only one inverterperforming as a master inverter, while the others are slaves con-trolled as current sources. The master inverter usually has twoselectable operation modes: current controlled for grid-tied modeand voltage controlled for islanded mode. The test facility consistsof a 2 kW single-phase photovoltaic inverter, a 17 kW three-phasephotovoltaic inverter, and a 15 kW customer made wind simula-tion system consisting of a permanent-magnet motor-generatorset, 100 kV A passive load bank and a 30 kV A active load unit, aprogrammable wind simulation to drive the motor to simulatedifferent wind turbine performances, and a 15 kW three phasegrid-tied wind turbine inverter for grid interface. Here theprogrammable DC power supplies and wind simulation converterare used in place of actual solar panels and wind turbine to maxi-mize the exibility of the testbed [3,37].

A high speed digital signal processor (150 MHz FPU) is used forthe master inverter, whose input is coupled to a 700 V lead-acidbattery array as shown in Fig. 8. A microgrid central control pro-vides various functions such as information management and dataacquisition, and system control of the microgrid. A high speedembedded PLC is used as the control platform for informationmanagement and data acquisition as a medium of communication.

3.4.2. Institute of Nuclear Energy Research, Taiwan (INER)In Taiwan, the very rst outdoor microgrid testbed was

designed and implemented by the Institute of Nuclear EnergyResearch (INER) in 2009 with a capacity around 500 kW. This radialtype microgrid consists of a wind turbine generator, high concen-tration PV, a gas turbine generator and battery.

e DGs_Nonrenewable Control Load Storage

Cell, Gas Agent based Static, Motor Battery

Diesel Centralized Static BatteryNo Centralized Static NoDiesel Decentralized Residential,

Commercial,No

Diesel, Gas Decentralized Static, Motor BatteryMotor Centralized Static, Motor BatteryNo Decentralized Residential, Motor Battery

y resource Capacity (kW) Purpose

110 Research110 Remote Community225 Tourism825 Remote Community660 Remote Community920 Remote Community3600 Remote Community1200 Remote Community600 Remote Community

Management 86 (2014) 132153 143Some of the key technologies of a distributed power system arewind turbine technology, PV module, stability and control tech-niques, power electronic converters, monitoring system and a pro-tection scheme where huge research is going on around the world.Among them, the study on the operation mode of high concentra-tion PV, voltage uctuation and switching motor have alreadystarted, but with this project researchers have mainly focused ongas turbine operation mode and this study has carried on for bothgrid-tied and islanded modes [9].

The Institute of Nuclear Energy Research microgrid testbed wasbuilt for achieving several goals. These are:

(1) To demonstrate recent developments in renewable technol-ogies by INER, for example high concentration PV and windturbine generator.

(2) To analyze and test the DG inverters properties in severalanomalous circumstances.

This project has been selected for its critical structure to con-duct various experiments on microgrids, such as isolated sensitiveloads and non-sensitive loads, having both series and parallel feed-ers, used non-renewable distributed generation (gas turbine) toimprove reliability, and used batteries for emergency backup planof the system as well. The schematic diagram of INER hybridmicrogrid testbed, which comprised of 18 AC buses and 4 DC buses,has been illustrated in Fig. 9.

In grid-tied mode, the gas turbines are deliberately operated inthe active and reactive control mode and if islanding occurs, onlyturbines are moved to the V/f control mode while others distrib-uted generations follow their previous P/Q control mode. Robustcontrol has been achieved by gas turbines to adjust amplitudesof voltage and frequency. Additional research has been done withthe gas turbines generators and batteries for both planned and

One of the rst Indian microgrid testbeds were installed around

mic

and2008 at the Institution of Engineering and Technology. The labora-tory scale distributed system is comprised of fuel cells through par-ticle swarm optimization based inverters, and 2.2 kW squirrel cageinduction generators through a PWM inverter. The total capacity ofthe grid-tied test facility is 5 kW at 50 Hz. The schematic diagramof the microgrid test setup has been illustrated in Fig. 10. The sineof the PWM inverter has been used to sustain the V/f control andunplanned island conditions. In an islanded microgrid, the batterysystem has served as a master controller and the performanceevaluation for both gas turbine generators inverters and batterysystems has been conducted. For piloting experiments, the INERmicrogrid used both static loads and motor loads where a powerline was used as a communication medium.

3.4.3. Test microgrid at the Institution of Engineering and Technology India

Fig. 8. Block diagram of144 E. Hossain et al. / Energy Conversionfrequency of the designed microgrid. Information regarding anystorage system or communication system has not been discussedin this project [6,37].

3.4.4. Microgrid testbed of Queensland University of TechnologyAustralia

Queensland University of Technology Australia has alreadystarted developing one of the rst institutional microgrid systemsas shown in Fig. 11. This radial type hybrid microgrid is comprisedof a nonrenewable distributed generation diesel generator and sev-eral renewable distributed generations, for example PV, FC andbattery as a storage system. To control the test facility, researchershave used the decentralized power sharing droop control tech-nique. There are four resistive heaters and six induction motorsto use as a microgrid load. Besides, several kinds of loads such asthe nonlinear load, unbalanced load and harmonic load have beenused for experimental purposes at bus 5. Fuel cells will help toincrease the power quality of DGs nearby where the nonlinear loadis connected. Moreover, PV or battery can be used to compensatefor power quality when nonlinear loads exist either at bus 3 ofbus 4. The storage device and PV share power with the DG whenthe fuel cell is preferred as a compensator. Based on feeding powerto a nonlinear load, the control system can adjust the mode ofoperation with any communication medium. Research shows thata low voltage DC distribution system, mainly dependent on PVs,can operate with the nonlinear loads and residential loads of acampus network. This nonlinear load study shows the feasibilityof single phase residential electricity supply from a PVs and DGsbased microgrid [11,14,45].

Table 10 presents a brief introduction of small microgridsaround the World. The details of the microgrids are providedaccording to name, location, and foundation year. Furthermore,they are classied according to non-renewable and renewablebased structures where the non-renewables are cited regardinggenerator types as diesel (D), stream (S), gas (G), hydro (H), andmotor drive (M), while the renewable-based microgrids areexpressed as wind, PV, fuel cell, and/or biogas sources. The micro-grid types are presented as being located in remote (R), utility (U),or campus (C) areas. All parameters to be emphasized in the col-umns are indicated with an inverted comma, i.e., that means therst microgrid (Utsira Island Wind & Hydrogen Park) is suppliedwith wind and fuel cells in terms of renewable DGs, while the stor-

rogrid testbed in China.Management 86 (2014) 132153age system is based on battery and ywheel. Table 11 shows themicrogrid testbed projects expressing the completed year, totalcapacity, location, and source types. Furthermore, control, storage,and load types are also depicted in Table 11 where the communi-cation types such as power line, Ethernet, optical, GSM or internetare expressed in a separate column.

Optimal Power Solutions (OPS) Inc. develops and implementsrenewable microgrids and utility storage projects. These includeadvanced optimizing operating cost and carbon footprint impactson the global environmental system. It has installed high penetra-tion renewable energy systems to meet the demands of speciclocations and resolve environmental concerns as well. Numerouselectrication projects at the rural and national level have beeninstalled by OPSs proprietary. In recent times, OPS have developedadvanced storage equipment suitable for connecting grid, solar,wind and storage [24]. A selection of signicant projects completedsince commencement is recorded in Table 12. The list of microgridprojects consists of inverter and renewable capacities besides thedistributed generation method. The last columns present the appli-cation mode as off-grid or grid-tied, and installation years.

4. Findings of the study

After the study of numerous microgrid facilities, it is discoveredthat the majority of microgrid testbeds have used AC power for

andE. Hossain et al. / Energy Conversionelectrication. So far the utility grid, the majority of electrical net-works and loads are AC, which helps the AC distributed microgridto participate with the utility grid without stress. However, one ofthe major concerns with AC systems is the power quality. Besides,the key advantage in a DC distribution system is fewer powerquality problems and consequently fewer components and less

Fig. 9. One line diagram of institute ofManagement 86 (2014) 132153 145complex control techniques are necessary. But, the application ofa DC microgrid is not popular due to the inaccessibility of sufcientDC loads, the complexity of its protection system and huge trans-mission loss for any distantly distributed system [9,10].

The most frequently used DG sources in microgrid systemsare solar PV, wind, micro-hydro, diesel and gas engine. Renew-

nuclear energy research microgrid.

and146 E. Hossain et al. / Energy Conversionable energy sources (RES) are reasonably popular as DG inEuropean regions together with conventional sources. Powerquality is an impending issue in a microgrid system. As therenewable DG sources are highly dependent on environment,

Fig. 10. Experimental mic

Fig. 11. The schematic diagram of the microgrid atManagement 86 (2014) 132153the intermittent nature of resources leads to several PQ prob-lems. Therefore, a consideration of PQ performance for anymicrogrid system is important where few microgrid testbedshave implemented power quality devices, as shown in the

rogrid at IET in India.

Queensland University of Technology Australia.

Table 10Several small microgrid around the World.

Several small microgrid around the world

Detail DGs_NonrenewableDiesel[D],Stream[S],Gas[G],Hydro[H]Motor DrivenGen[M]

DGs_Renewable Storage MicrogridTypeRemote[R]Utility[U]Campus[C]AC/DC

TotalCapacitykW

Remarks

Name Place Country Year Wind PV FuelCell

Biogas Battery Flywheel Capacitor

Utsira Island Wind& HydrogenPlant

Utsira Island Norway 2008 M 00 00 00 00 U, AC 2000 Grid-tiemicrogrid tosupply for 10houses

Hawii HydrogenPower Park

Hawii USA 2012 00 00 00 00 R, DC 200 Remote testfacility.

FC-CHP based Plant Osaka Japan 2009 00 C, AC 300 For hot watersupply

Mannheim-Wallstadtresidential Plant

Mannheim Germany 2003 00 R, AC 30 For shiftingpeak load

Continuons MV/LVPlant

Holland TheNetherlands

2003 00 00 U, AC 315 To improvepower quality

LABEINsCommercialfeeder

Spain 2011 D, M 00 00 00 00 U, AC 200

Demonstration ofDistributedGenerationTechnologies

The lhavoMunicipal Plant

Coimbra Portugal 2009 D, M u, AC 300 Analysis ofmicrogridbehaviour

Kozuf Microgrid KozufMountain

Macedonia 2007 00 00 R, AC 5 For sleepfoldand ski-centre

Dolan CM test bed Ohio USA 2002 M U, AC 60 Foremergencysupply

San DiegoMicrogrid Plant

California USA 2007 S, G 00 C, AC 18000 For campussupply

Santa Rita Jail Plant Dublin USA 2011 D 00 00 00 00 U, AC 5000 ForuninterruptedpowerBornholm Multi

microgridLyngby Denmark 2007 D, S 00 00 00 00 U, AC 55000 For stability &

blackstartEDP

microgenerationfacility

Portugal 2008 G 00 00 U, AC 50000 Forillustratingmicrogrid

Eigg island plant Scotland H 00 00 00 R, AC 144 For islandpower supply

Microgrid testfacility inYokohama

Japan 2008 G 00 00 00 00 R, AC 100 ForYokohamaresearchInstitute

CSIRO Energycenter

Newcastle Australia 2010 G 00 00 00 U, AC 500 Forsupportingsupply

Singapore pulauubin microgrid

Pulau Ubin Singapore 2011 D 00 00 U, AC 1000 For domesticapply

Korea KEPRImicrogridproject

Yuseong-gu Korea 2011 D, G 00 00 U, AC 400 For planningof futureconstructionandoperational

KERI MicrogridSystem

Jeju Island Korea 2008 D 00 00 00 00 R, AC 100 For

establishment ofpilot microgridSan Juanico Plant San Juanico Mexico 2004 D 00 00 R, DC 200 For remote

communityManzanita Hybrid

Power PlantCalifornia USA 2005 00 00 00 U, AC 15 For

communitypower supply

Sunwize PowerPlant

a Canada D 00 00 00 R, AC 15 StandbyPower system

Santa Cruz Island California USA 2005 D 00 00 R, DC 300 For US Navy

(continued on next page)

E. Hossain et al. / Energy Conversion and Management 86 (2014) 132153 147

Rene

PV

00

00

00

00

andTable 10 (continued)

Several small microgrid around the world

Detail DGs_NonrenewableDiesel[D],Stream[S],Gas[G],Hydro[H]Motor DrivenGen[M]

DGs_

Name Place Country Year Wind

Xcalac Microgrid Xcalac Mexico 1992 00

CampinasMicrogrid

Campinas Brazil 2001 D

Azores Island Plant Azores Portugal 2005 D, H 00

SGEM HailuotoMicrogrid

Hailuot Finland 2012 D 00

WoodstockMicrogird

Minnesota USA 2001 00

00

148 E. Hossain et al. / Energy Conversionsummary of the review. Hence, supplementary research is essen-tial to improve microgrids PQ issues as well as stability and reli-ability issues to increase the performance and power quality ofmicrogrid systems.

The storage system is one of the most important choices for thesuccessful and stable operation of a microgrid. Although the bat-tery banks are the most popular ones, some of the existing testbedshave various sorts of storage devices such as a ywheel or supercapacitors. Few of them have a combination of several storageunits together and very few systems are without any storage unitwhere a controllable DG source is present. Grid-tied connectionis important when a renewable distributed system short of storagedevice needs to maintain system stability.

Key benets of the microgrid:

The foremost benet of the microgrid is its ability to operate inislanded mode when there is any disturbance in the utility grid,or for economical purposes. Hence, it increases the overall sys-tem reliability [38].

During peak load time, the microgrid helps the utility grid tofunction properly by sharing its loads, hence failure of the util-ity grid can be prevented.

Gazi UniversityEnergy park

Ankara Turkey 2007

Mt. NewallMicrogid

Mt. Newall Antarctica 2002 D 00 00

Isla Tac Microgidplant

Isla Tac Chile 2002 G 00

Subax residentialmicrogrid

Subax China 2006 G, D 00 00

Dangling RopeMarinaMicrogrid

Utah USA 2001 00

Kotzebue MicrogridPlant

Alaska USA 1997 D 00

Alto BagualesMicrogrid Plant

Coyhaique Chile 2001 D, H 00

Wales AlaskaPower Plant

Alaska USA 2002 D 00

St. Paul Power Plant Alaska USA 1999 D 00

Ascension IslandPower Plant

AscensionIsland

Canada 1996 D 00wable Storage MicrogridTypeRemote[R]Utility[U]Campus[C]AC/DC

TotalCapacitykW

Remarks

FuelCell

Biogas Battery Flywheel Capacitor

00 R, DC 150 For villagesupply

00 R, DC 150 Forresidentialsupply

U, AC 2000 For increasinggrid stability

U, AC 2000 For locallysupport ofgrid

00 U, AC 5 Formaintainingshop & ofce

00

Management 86 (2014) 132153 Microgrid utilities use local green energy to feed local demandinstead of using fossil fuel, hence lowering its carbon footprint.

Opportunity for big customers/companies to improve powerquality and power stability.

Small (microgrid) macrogrids are easy to control. The microgridusually used on the West coast grids acts as a capacity driver,and East coast grids as a power quality and stability issue. How-ever, in Chicago the microgrid has both uses.

Combined heat and power (CHP) with a non-renewable gener-ator helps to improve overall efciency [36].

In the microgrid system, users can produce their demandedenergy, which mitigates the electricity costs.

A microgrid can remove stress from a macrogrid. Generation and demand are happening at the distribution levelwithout transmission. Hence, it reduces the network and trans-mission losses and provides local voltage support as well.

Several problems of the microgrid:

It is hard to maintain the standard level of voltage, frequencyand power quality while continuing to maintain balance withintermittent supply and variable demand.

C, AC 5 For feedinglaboratory

R, AC 10 For sciencefoundationstationproject

00 R, AC 40 For islandedcommunity

00 R, AC 50 For isolatedcommunity

160 For nationalpark center

R, AC 11000 For remoteareaapplication

R, AC 23000 For remotepower supply

00 R, AC 500 For ruralcommunitysupply

R, AC 500 Forindustrial/airportfacility

R, AC 225 For Islandcommunity

Table11

Summaryof

microgrid

projects.

Summaryof

microgrid

project

Situation

DGsrenew

able

DGs

MicroturbineMicrogrid

application

Distribution

type

Power

nature

Microgrid

type

Con

trol

Load

Storage

Com

municationRem

arks

Nam

ePlace

Cou

ntry

Year

Total

capa

city/

Ren

ewab

leMW

Solar

thermal

PVWindFu

elcell

CHPHyd

ro[00]/

Others[Nam

e]Diesel[D]

Stream

[S]

Gas[G]

Motor

Driven

Gen

[M]

Facility(Cam

pus/

Indu

strial)[C]/

Rem

ote[R]/

Utility[U]

Mesh[M

]/Rad

ial[R]

AC/DC

Real[R]/

TestBed

[TB]

Both[B]

Cen

tralized

Decen

tralized

(Autonom

ous)

Agent

based

Residen

tial[R]/

Com

mercial[C]/

Indu

strial[I]

Static

Motor/

Electron

icsBattery

[B]

Flyw

heel[FW

]Cap

acitor[C]

Others[Nam

e]

Power

Line[PL]

Others[Nam

e]Optical

Fibe

rNetwork[OP]

NO

BostonBar

BCHyd

roBritish

Columbia

Can

ada

2008

1500

DU

RAC

R00

RTeleph

one

Toim

prov

edreliab

ilityan

dsupp

lysecurity

Boralex

Plan

tQube

eCan

ada

2005

31S

UR

AC

R00

Ra

Forreplacem

ent

feed

erCER

TSTestbe

dOhio

USA

2009

0.2

GC

MAC

TB00

RB

Ethernet

To demon

stration

ofMicrogrid

UW

Mad

ison

Testbe

dWisconsin

USA

2008

0.02

00D

CR

AC

TB00

00B

Ethernet

Tode

velop

robu

stplug-an

d-play

power

control

BronsbergenPark

Microgrid

Zutphen

The

Netherlands

2009

0.3

00R

MAC

R00

RB

GSM

Toprov

idepo

wer

holiday

park

Am

Steinweg

Microgrid

Stutensee

German

2005

0.2

0000

UM

AC

R00

RB

Internet

Protocol

Forreside

ntial

power

supp

lyCESIRICER

CADER

Testbe

dMon

eta

Italy

2006

0.5

0000

0000

DU

RDC

TB00

RB,FW

PL,W

ireless

Tope

rform

differen

texpe

rimen

tation

sKythnos

Island

Microgrid

Kythnos

Island

Greece

2001

0.05

00D

RR

AC

R00

RB

PLTo

supp

lyremote

island

NTU

AMicrogrid

Athen

sGreece

2004

0.01

0000

CR

AC

TB00

00B

PLFormicrogrid

research

DeM

oTec

Testbe

dKassel

German

2002

0.2

0000

DC

MAC

TB00

R,C

BEthernet

Forinvestigating

renew

able

technolog

yUniversity

ofMan

chester

Testbe

d

Man

chester

UK

2005

0.2

MC

RAC

B00

0000

FWPL

Formicrosource

interfacewith

storage

AichiMicrogrid

Toko

nam

eJapa

n20

051.2

0000

Biogas

CR

AC

R00

C,I

BPL

Tomaintain

airportsupp

lyKyo

toeco-en

ergy

Microgrid

Kythnos

Island

Japa

n20

050.4

0000

00G

UM

AC

R00

RB

Ethernet

Power

generator

from

biog

asHachinoh

eMicrogrid

Hachinoh

eJapa

n20

051

0000

Biomass

GU

RAC

R00

C,I

BPL

Forincreasing

power

quality

CRIEPI

Microgrid

Akagi

Japa

n20

030.3

00U

MAC

R00

00No

OP

SVC&SV

Rregu

late

voltage

Senda

iMicrogrid

Senda

iJapa

n20

061

0000

GU

RAC

R00

R,C

,INo

GPS

Tode

mon

strate

power

qualityby

PQR

HFU

TMicrogrid

Anhui

China

2006

0.3

0000

0000

DC

MAC

TB00

0000

BPro

bus

Emulation

platform

for

Microgrid

Tian

jinUniversity

Testbe

dTian

jin

China

2007

0.00

500

00C

RAC

TB00

00B

RS48

5For

expe

rimen

tation

purpose

Test

Microgrid

atIET

aIndia

2008

0.00

500

MC

RAC

TB00

00a

Storage&

Com

munication

aren

tdiscussed

Ben

chmarklow

voltageMicrogrid

Athen

sGreece

2002

0.1

0000

00U

RAC

TB00

00R

B,FW

NO

Forsimulation

ofmulti-feed

ermicrogrids

VSC

feed

edMicrogrid

Toronto

Can

ada

2006

0.01

MC

RAC

TB00

0000

CNO

Study

onVPD

/FQ

Bcontrol

schem

eUniversity

ofMiami

Testbe

dFlorida

USA

2007

0.01

0000

CR

DC

TB00

RB

NO

Hierarchical

hyb

ridMicrogrid

paradigm

Nim

busMicrogrid

Testbe

dCork

Irelan

d20

060.2

0000

00U

RAC

B00

RB

Wireless

Strategic

resourceforCIT

&Researchpu

rpose

MSEDCLat

Wan

iArea

Microgrid

Mah

arashtra

India

2011

18.5

00Biomass

UM

AC

R00

R,C

,IPL

Forsupp

orting

utility

grid

INER

Microgrid

Testbe

dLongtan

Taiw

an20

090.5

0000

GC

RAC

B00

0000

BPL

Battery

andgas

turbineprov

ide

stab

ility

(con

tinu

edon

next

page)

E. Hossain et al. / Energy Conversion and Management 86 (2014) 132153 149

Table11

(con

tinu

ed)

Summaryof

microgrid

project

Situation

DGsrenew

able

DGs

MicroturbineMicrogrid

application

Distribution

type

Power

nature

Microgrid

type

Con

trol

Load

Storage

Com

municationRem

arks

Nam

ePlace

Cou

ntry

Year

Total

capa

city/

Ren

ewab

leMW

Solar

thermal

PVWindFu

elcell

CHPHyd

ro[00]/

Others[Nam

e]Diesel[D]

Stream

[S]

Gas[G]

Motor

Driven

Gen

[M]

Facility(Cam

pus/

Indu

strial)[C]/

Rem

ote[R]/

Utility[U]

Mesh[M

]/Rad

ial[R]

AC/DC

Real[R]/

TestBed

[TB]

Both[B]

Cen

tralized

Decen

tralized

(Autonom

ous)

Agent

based

Residen

tial[R]/

Com

mercial[C]/

Indu

strial[I]

Static

Motor/

Electron

icsBattery

[B]

Flyw

heel[FW

]Cap

acitor[C]

Others[Nam

e]

Power

Line[PL]

Others[Nam

e]Optical

Fibe

rNetwork[OP]

NO

Gen

oaUniversity

Gen

oaItaly

2013

0.2

0000

00G

CM

AC

TB00

RB

OP

Testbe

dfor

campu

s,indu

stries

&man

ufactures

SandiaNational

Lab

Testbe

dWashington

,DC

USA

2012

0.06

0000

DC

RDC

TB00

R00

Emulator

Ethernet

Highpe

netration

stochastic

renew

ables

NUAATestbe

dNan

jing

China

2012

0.1

0000

MC

RAC

TB00

0000

BPL

Evaluatethe

control

method

sUniversity

ofNottingh

amTestbe

d

Nottingh

amUK

2011

0.5

00C

RDC

TB00

RB

LAN,G

PRS

Areal

time

microgrid

emulator

UTArlington

Testbe

dTexas

USA

2011

0.01

0000

00D,G

CR

DC

TB00

R00

BPL

Forad

vanced

research

platform

forUS

Navy

FIUTestbe

dFlorida

USA

2008

0.01

0000

00M

CR

DC

TB00

00R

00FW

PLHyb

ridgrid

toop

timize

operating

techniques

Labo

ratory

scale

microgrid

testbe

dNew

Jersey

USA

2011

0.01

00U

RAC

R00

R00

BWireless

Gen

erator

Emulation

Con

trolsfor

stab

ilizinggrid

UTAustin

Texas

USA

2010

5D,G

,MC

RAC

TB00

0000

FWNO

Shipbo

ardpo

wer

system

sUTCom

pigne(UTC

)Testbe

dCom

pigne

Fran

ce20

110.01

0000

CR

DC

TB00

00B

PLBuilding-

integrated

microgrid

for

stab

lepo

wer

University

ofSeville

SpainTestbe

dSeville

Spain

2012

0.01

0000

CM

DC

TB00

R00

BCANbu

sRep

resentation

oflongterm

performan

ceQUTMicrogrid

Testbe

dQueenslan

dAustralia

2010

0.01

500

00D

CR

DC

TB00

R00

BNO

Toinvestigate

microgrid

power

quality

Microgrid

testbe

dat

Albuqu

erqu

eNew

Mexico

USA

2010

2.5

0000

00G

UR

AC

R00

R,C

00B

PLTo

supp

ort

commercial

area

load

Utility

Microgrid

atLos

Alamos

New

Mexico

USA

2011

2.5

00U

RAC

R00

RB

OP

US-Japa

nCollabo

ration

projectfor

Microgrid

RIT

Microgrid

New

York

USA

2013

0.6

0000

00Biogas

CM

AC

TB00

R00

00PL

Geothermal

isusedto

warm

up/

cool

down

buildings

Mad

River

Park

Microgrid

Vermon

tUSA

2005

0.5

00D,M

RM

AC

R00

R,C

,IB

aReliablepo

wer

arou

ndMad

River

microgrid

Palm

dale

water

district

power

system

California

USA

2006

400

00D,G

UR

AC

R00

R,C

0000

Ca

Energy

bridge

ofrenew

ables&DG

technolog

ies

Ram

eawind-diesel

Microgrid

NL

Can

ada

2004

3.5

00D

RM

AC

R00

RB

Wireless

Power

forremote

shery

community

Fortis-Alberta

Microgrid

Alberta

Can

ada

2006

700

00U

RAC

B00

Ia

aIndu

strial-grade

microgrid

prototyp

eBCIT

Microgrid

BC

Can

ada

2008

1.2

0000

SC

RAC

B00

R,I

0000

BPL,Fiber

Add

ressing

critical

issues

ofmicrogrid

Haw

aiiHyd

rogen

Power

park

Haw

aii

USA

2013

0.03

0000

00R

RDC

TB00

R00

BNO

Small-scaleDG

system

sfueled

byhyd

rogen.

FEUPMicrogrid

Testbe

dPo

rtoDistrictPo

rtugal

2005

0.1

0000

00M

CR

AC

TB00

RB

PLCam

pus

microgrid

for

research

purpose

a:Noda

tafound.

150 E. Hossain et al. / Energy Conversion and Management 86 (2014) 132153

ertepacit

0 kW

0 kWMWWMW

kW5 kW5M

W5 kW

W0 kW0 kW0 kWW

andTable 12List of selected microgrid projects by Optimal Power Solutions Inc.

Microgrid project of Optimal Power Solutions Inc (OPS)

Location Project manager Invca

Maluku & Makassar Islands-Indonesia

PLN Utility, Indonesia 50

Maluku Islands-Indonesia PLN Utility, Indonesia 25South India BHEL 10India BHEL, India Bulls 6 MLakshadweep, Bangaram Islands-

IndiaBHEL 1.1

Marampit Province-Indonesia PLN Utility, Indonesia 75Maluku Province-Indonesia PLN Utility, Indonesia 27Morotai Island, Moluccas-

IndonesiaPLN Utility, Indonesia 1.3

Raichur, Karnataka-India BHEL, India 3 MBunaken, Indonesia PLN Utility, Indonesia 21

Karnataka-India KPCL-State Utility 3 MKinabatagan, Sabah-Malaysia KKLW Rural Ministry 98Superior Valley-USA Private Client 18Over Yonder Cay Island-Bahamas Private Client 60Raj Bhavan Governor House- WBGEDCL, Ministry of New & 5 k

E. Hossain et al. / Energy Conversion For reliability purposes, a storage device is required which occu-pies more space and maintenance.

It is difcult to achieve synchronization with the utility grid. A distributed system could create stress for the macrogrid whenit operates as a load.

A sophisticated protection system is the challenge in imple-menting the microgrid.

The microgrid has critical issues for example, standby chargesand net metering which need to be addressed [18,22].

A better interconnect standard is needs to be developed forkeeping consistent with IEEE P1547.

Adding more uncertain sources (like wind, solar) means it ismuch more difcult to control centrally (Eastern/Western grid),but it is easy to control locally by knowing the behavior of theload.

Utilities produce more fossil power after monitoring that moresolar/wind power is connected to the system because of itsintermittent nature.

Huge harmonics effects from the inrush current of transformersor Induction machine [37].

Three phase unbalance could occur from single phase loads ofsingle phase generators such as photovoltaic [18].

Several features are required to achieve exibility of the micro-grid [17]:

Kolkata Renewable EnergyJamuria-West Bengal Disargarh Power Corporation (DPC) 2 MWTelupid, Sabah (Malaysia) Ministry of Education Malaysia 105 kWKalabakan, East Sabah (Malaysia) TNB-ES, Ministry of Education 555 kWIdaho-USA Idaho Power-US Air Force 150 kWOrang Asli Project-2, Malaysia TNB-ES Malaysia 90 kWHyrid Power Systems-Indonesia PT Len 150 kWIndonesia PT Nabgunbaskara 20 kWOrang Asli Project-1, Malaysia TNB-ES Malaysia 285 kWVillages Sabah Power Systems,

MalaysiaTNB-ES Malaysia 225 kW

PulauTinggi, Mersing-Malaysia TNB-ES Malaysia 90 kWPerhentian Island-Malaysia TNB-ES Malaysia 450 kWSchool Sabah Power Systems-

MalaysiaMinistry of Education 225 kW

Arizona-USA APS Greywolf Project 90 kWBandung-Indonesia Alstom 145 kWLighthouse Locations-Indonesia Ministry Project 260 kWPhilippines Dumalag/Matec 40 kW

Santa Cruz Island, USA United States Navy 90 kWLakshadweep Islands, India BHEL, India 60 kWMersing Islands, Malaysia TNB-ES Malaysia 360 kWry

Renewablecapacity

Distributed generation Applicationmode

Time

700 kW Solar PV, Diesel, Hybrid Off-grid 2012

225 kW Solar PV, Diesel, Hybrid Off-grid 201210 MW Solar PV Grid-tied 20126 MW Solar PV Grid-tied 2012

p 2 MWp Solar PV, Diesel, Hybrid Off-grid 2012

150 kWp Solar PV, Diesel, Hybrid Off-grid 2012405 kW Solar PV, Diesel, Hybrid Off-grid 2012

W 600 kW Solar PV, Battery Off-grid 2011

3 MW Solar PV Grid Connect Grid-tied 2011353 kW Solar PV, Diesel, Hybrid

Off GridOff-grid 2011

3 MW Solar PV Grid Connect Grid-tied 2010220 kW PV, Diesel Off-grid 2010120 kW Solar PV Grid-tied 2010360 kW PV, Wind, Diesel Off-grid 20101 kW Solar PV Grid-tied 2009

Management 86 (2014) 132153 151 The microgrid should be capable of following the voltage ride-through standard of that particular area.

It is very important to have a black-start quality if the systemneeds to restart for natural disaster or maintenance purposes.

The microgrid needs to estimate grid impedance prior to some-thing being connected or disconnected to it.

The most important feature which would give the microgridbetter control is storage energy management and a comprehen-sive control system.

5. Conclusion

Right now, modern nations produce the majority of their powerin expansive unied ofces, for example, fossil fuel, atomic or hydro-power plants. These plants have great economies of scale, howevergenerally transmit power across long separations and contrarilyinuence nature. Most plants are manufactured thusly because ofvarious monetary, health & security, logistical, natural, land andtopographical variables. The dispersed era is an alternate methodol-ogy. It diminishes the measure of power lost in transmitting powerin light of the fact that the power is created quite close to where it isutilized, maybe even in the same building. This additionallydecreases the size and number of force lines that must bedeveloped. Previously, these attributes required devoted

2 MW Solar PV Grid-tied 2009100 kW Hybrid Power Conditioner Off-grid 2009250 kW PV, Diesel Grid-tied 200977 kW PV, Diesel Off-grid 200845 kW PV, Diesel Off-grid 2008 PV, Diesel Off-grid 2007 Hybrid Power Conditioner Off-grid 2007138 kW PV, Diesel Off-grid 2007105 kW PV, Diesel Off-grid 2007

40 kW PV, Diesel Off-grid 2007280 kW PV, Wind and Diesel Off-grid 2007190 kW PV, Diesel Off-grid 2007

40 kW PV, Diesel Off-grid 2006 GSC Systems Off-grid 2006 PV, Diesel Off-grid 200630 kW Hybrid Power

ConditionersOff-grid 2006

137 kW PV, Diesel Off-grid 200525 kW PV, Diesel Off-grid 200585 kW PV, Diesel Off-grid 2004

increase the efciency [7,31].

152 E. Hossain et al. / Energy Conversion and Management 86 (2014) 132153Different tests are required to achieve a cleaner and moresecure transmission framework, while the administration frame-work should be handled by comparative exploration ventures.The results of studies performed on microgrids will support theimprovement of secure, solid, and stable genuine systems withmore terric entrance of RE sources. This will be supportive inaccomplishing a more solid, secure and cleaner power without bar-gaining on environmental assurance and comparable ideas.

Research into microgrids has been developed everywherethroughout the world. Thusly, a few nations, for example, Canada,Japan and USA are occupied with a few exploration tasks managingmicrogrids. Around the exploratory microgrids being mulled over,it has been demonstrated that the greater part of the microgridsactualized utilization of AC transmission frameworks withcentralized controls. It has likewise been seen that islandedmicrogrids assume an essential part in rustic jolt ventures every-where throughout the world. At long last, various issues, for exam-ple, circuit insurances, DC dispersion frameworks and optimaloperation of the entire framework still require an extraordinaryarrangement of committed research to certify a suitable improve-ment of microgrids later on [40,41].

The DC microgrid is not extremely prominent in European dis-tricts, however it has points of interest with respect to lesser forcequality issues; more stress ought to be provided for this frame-work. The fundamental boundary to extend this innovation is oflesser measure than DC burdens. A large portion of the existingAC microgrid testbeds have incorporated electric storage devicesas space units, however it is impractical; further mechanicalchange can help the framework to end up nancially practical.More use of RESs is normal in microgrid frameworks as they arevery nearly contamination-free and hence environmentallyfriendly. All things considered, potential exertion ought to be pro-vided to take care of force quality issues associated with therenewable power sources. The fusion of distinctive renewableframeworks plus space has a potential future in light of the factthat it serves to store the clean power at whatever point is acces-sible. The progression in reserve and electric storage device frame-works looks encouraging as far as expense and engineering go.Despite the fact that introductory framework expenses and opera-tion and upkeep expenses may be higher, recognizing the necessi-ties of interest on the side of administration and augmenting theutilization of accessible RESs, microgrids with space units couldbe a feasible choice within a brief period of time.

This paper has displayed the ebb and ow status of the literaryworks related to microgrid examination. It has depicted the micro-grid thought and the inspirations driving its usage then delineatedthe diverse examination elds under this heading. The currentexploration work was condensed to give a general understandingabout the present level of the information. At long last, conceivableexamination zones have been proposed which are fundamental forfuture improvement.

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