Real-World Micro Grids- An Overview

Real-World MicroGrids- An OverviewMike Barnes Giri Ventakaramanan

School of Electrical and Electronic Engineering Electrical & Computer Engineering DepartmentUniversity of Manchester, Manchester, MI 7AB, UK University of Wisconsin, Madison, WI, U.S.A.

mike.barnes @ manchester.ac.uk g.ventakaramanangengr.wisc.edu

Junji Kondoh Robert LasseterNational Institute of Advanced Industrial Science and Electrical & Computer Engineering Department

Technology (AIST), Tsukuba 305-8568, Japan University of Wisconsin, Madison, WI, U.S.A.J.kondohgaist.go.jp lasseter(engr.wisc.eduHiroshi Asano Nikos Hatziargyriou

Department of Mechanical Engineering School of Electrical and Computer Engineeringthe University of Tokyo, Tokyo, Japan National Technical University of Athens, Greece

[email protected] vnhcorfu.power.ece.ntua.grJose Oyarzabal Tim GreenEnergy Unit Department of Electrical and Electronic Engineering

Labein - Tecnalia, 48160 Derio, Spain Imperial College, [email protected] t.greengimperial.ac.uk

Abstract - Microgrids are networks of small, distributed There exists considerable research to date onelectrical power generators operated as a collective unit - Microgrids with a number of major research projectsa system of energy systems. The range of hardware and underway, for example [1-8]. A number of demonstrationcontrol options for Microgrid operation are reviewed. The projects have been commissioned internationally. Howeverpaper summarizes and highlights the operating principles development of these systems and projects has largely beenand key conclusions ofresearch andfield trials to-date. An undertaken independently. For the first time, this paperoverview is given on demonstration projects for brings together information from these field trials, in theMicrogrids which have been, and are being, constructed. context of research to date. The information presented is

perforce limited, in so far as public information on someKeywords: Microgrids, renewables, power quality, energy projects is limited. Space also precludes the discussion ofstorage, distributed generation, micro-generation. many of the smaller laboratory-scale Microgrids at

universities (as used for example in [2-5]).1 Introduction

The use of micro-generation based on combined heat 2 Microgrid Structuresand power (CHP) or small-scale renewable generation has The topology elements required in a Microgrid area significant potential for reducing our dependency on strongly dependent on its operating states. A Microgrid hasfossil fuels. Since this could turn many consumers of two steady states of operation: grid connected operationelectricity into net producers, this strategy is not easily

accmmoatd i peset istibtio ntwoksand islanded. It also has two transient states, correspondingto the transitions between these steady-states. During allthese four conditions it must remain stable and must meet

The Microgrids concept has been proposed [1] as a grid-code requirements (e.g. on real and reactive powersolution to the conundrum of integrating large amounts of flow and behaviour during faults).micro-generation without disrupting the operation of theutility network. By judicious intelligent coordination of The generalized structure and potential topologicalloads and micro-generation the aggregate distribution elements of a Microgrid are shown in figure 1. Not all ofnetwork sub-system (or 'Microgrid') would be less these system elements need be used, and the choice andtroublesome to the utility network, than conventional combination of possible elements determines the potentialmicro-generation. The net Microgrid could even provide capability of a microgrid, i.e. how 'well behaved' it can beancillary services such as local voltage control. During made to operate. Ultimately, compared with a conventionaldisturbances on the main network, Microgrids could system, additional hardware and software are required topotentially disconnect and continue to operate control the voltage and power flows in the aggregateautonomously. This operation has the potential to improve sse opoueteipoe eaiu eurdopower quality to the consumer. Microgrid.

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The connection interface (CI) to the utility network network voltage (power line carrier) or even by modulation(1, figure 1) can be something as straightforward as an of the frequency and voltage of the Microgrid (e.g. 'droop-electro-mechanical circuit breaker, although solid-state line' control). The coordination can be achieved by aswitches and even back-to-back (AC/DC/AC) power dedicated control unit or tuning the individual unit localelectronic inverters have been proposed. controllers a priori during the design stage.

Some form of fast-acting energy absorption and Clearly the steady-state coordination of loads andinjection capability (2, figure 1) is usually required to micro-generation is an important topic [9]. However it isbalance power flows at the onset of Microgrid islanding. In the transient behaviour requirements of semi-autonomousa more sophisticated Microgrid control scheme, energy operation which determine much of the additional cost of astorage could also be used to control the net power flows to Microgrid over conventional distributed generation. Anand from the utility in the grid connected mode, allowing example of such behaviour is the control response tothe Microgrid to behave as a 'model' citizen, capable maintain system stability during islanding. Proposals forassisting stable network operation by providing improved Microgrids can be categorized roughly into three types,power quality and voltage control for example. depending on how they achieve this transient (short time-

frame) stability:Point of Couplng

(P_C) nrUW 1A. Virtual 'Prime Mover' - In this scheme a central

ET G2 controller samples Microgrid state variables and dispatchesUtility network C&ftL r- signals to all (or at least the dominant) micro-sources using

fast telecommunications. This aggregation creates one5Y 8 PE| 1|1 1_ 4 virtual power supply unit which dominates and controls the

Possible Power Microgrid's behaviour. Problems with this method are the11Electwnxcsilerface 55 need to achieve a reliable communications system, the need

CorinecUonMtr for some back-up control should the communications fail,

Communication G-----r - the telecommunications cost and the restriction imposed by__OMMXitStn AGA eneratortline1 I6 ft/lalPElimited numbers of telecommunications channels /V I sensor Photovolts a _Ibandwidth on Microgrid expansion.

NumtOr See text tfr descriptionGeneral load (impedance, or 7 B. Physical 'Prime Mover'- In this scheme a largemotr, or powr elteronics). central hardware unit, either energy storage or generation,

is controlled to handle transient power flows and setFigure 1. Potential Microgrid System Technologies iscnrletohdetasetpwrfosadstFigure1.PotentialMicrogridSystemTechnologies voltage magnitude and frequency to balance steady-state

real and reactive power flows in islanded mode. ProblemsThe characteristics of the loads and micro-generation are the cost of the central unit (or aggregate unit if multiple

(i.e. 3-7, figure 1) determine the requirements for energy units are paralleled), the reliance of Microgrid operation onstorage and power quality in the Microgrid. In general the this centralluit(ie ove relia bility) an thaddition of a power electronics interface to a unit adds difficulty of sizing the central unit bearing in mind theextra controllability and increases the unit's speed of potential for future changes in load and micro-generation.response. Local energy storage in conjunction with a powerelectronics interface (for example on the dc link of the C Distributed Control - In this last scheme each unitpower electronics) can add robustness. As a crude form of responds to variation in local state variables, typicallycontrol, non-critical loads may have under-frequency load- voltage magnitude and frequency. A slow central controllershedding relays (e.g. 7, fig. 1). Load power electronics may send signals to vary steady-state (nominal) set-points,interfaces in contrast could potentially be used to provide but for redundancy, local control determines transient andcontinuously variable power consumption by non-critical default behaviour. The speed of response of the distributedpower loads (e.g. ventilation). Power electronics interfaces elements must be sufficient to ensure stable Microgriddo have disadvantages; they potentially increase harmonic operation with careful Microgrid design. This type ofinjection and can be quite sensitive to systems control typically requires that micro-generation units havedisturbances. power electronic interfaces to achieve the fast response

required. An 'intelligent' connection interface is alsoThere must be some degree of central control (8, needed to reconnect the Microgrid to the utility network

figure 1) or co-ordination between all Microgrid elements when their voltages (which will need to be at differentin order that they operate as a system. Common Microgrid frequencies by design) pass close to alignment. Carefulstate variables, instantaneous phase voltages and currents at system design is necessary to balance loads and generationthe point of coupling, must be regulated. The drn sadn n eoncinwtotuacpalcommunication required can be by means of a voltage disturbance.telecommunications line, a signal superimposed on the

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The Microgrid implementations described below have two commercial customers (in the initial, phase A, ofbeen categorized further by geography and the research project) and serves a mixed load set [12]. The mediumconsortia which were involved in their implementation i.e. voltage switch and NPS new building are controlled by aAmerican, Asian and European. central Microgrid controller. Although the central

controller, and absence of storage, makes this is a type A

3 American Microgrids Microgrid, the autonomous micro-generation makes thedesign of this type of Microgrid extremely challenging.

3.1 AEPCERTS

PoC 1~kI$Vvrar od Utilty networkCer_~~~~~~~~ I 14v ra le Z loa I-95kWh peak X 7.2kV 4

variabe Z load, .PEEG 20WUtiIlty I95kW peak P0 fbse

500kVA prop negen et

100kWabIE H _ 25kVA cri ica biodieselPE variable Z load, Vltoad bus genset

6OkW ~~~~2Ohp motor load bulddIng) Pvariable Z load, II 2.5kVA

30I

95kW peak

Figure 2. CERTS AEP Microgrid - Micro-generation mi(rNPStondconnection transformers and relocatable harmonic load not G P building) 100kW biodiesel

shown. genW

The Consortium for Electric Reliability Technology Figure 3. Mad River MicrogridSolution (CERTS) Microgrid is a collaboration betweenAEP, TECOGEN, Northern Power Systems, S&C Electric 3.3 BC Hydro Boston BarCo, Sandia National Laboratories and the University ofWisconsin. The facility is located at the AEP Walnut Test The British Columbia Hydro Boston Bar substationfacility and is formed by a radial feeder with line lengths allows intentional islanding of a feeder with 3MW peakup to 175 yards, connected through a 1.5MVA load and 8.6MVA of hydroelectric generation [11]. Power480V/13.2kV transformer to the utility. Three 60kW outages occur severalytimesperiyear forebetweenl12 and20Tecogen Combined Heat and Power Sources, driven by hours Studies of system islanding, resynchronization andnatural gas fed engines, form the Micro-generation. They black-start on this system (by means of a 50kW diesel-are interfaced by controlled inverters which use terminal generator) are useful for Microgrid technologyvoltage and real power export as the control variables, with development. The system effectively employs a singlea combination of P-f and V-Q droop line and PI control large generation station to control the net sub-systemloops [10,11]. Four load banks are used. Three are behaviour, i.e. uses type B Microgrid control.impedances which can be varied in steps (with a peak real

* * 6~~~~~~~~~~~~~~~~~~~~~9kV25kVpower rating of 95kW). A fourth load bank also includes a Utiliy network 1Mdirectly connected induction motor, to allow islandedmotor starting tests. Energy storage is integrated via abidirectional dc:dc converter into the dc link of the power POCelectronics interface of the micro-generation. The systemhas been designed so that the critical loads are located to 3MW peak 043MVA hydrothe right of the solid-state (anti-parallel thyristor)

4 h

connection interface (figure 2) and there is alwayssufficient CHP micro-generation / dc-link storage power tomeet the total critical load power. This is a type C Figure 4. BC Boston Hydro BarMicrogrid.

3.4 GE Microgrid3.2 Mad River

The General Electric Corporation is in the process ofNorthern Power Systems (NPS) has built a Microgrid gearing up for field trials of its Microgrid concept. The

installation at Mad River, Waitsfield, Vermont. The company has undertaken a $4.2million program to developindustrial park includes Northern's headquarters as well as


a 'Microgrid Energy Management System" [7], i.e. a type work highlights two key points. Firstly, as a result ofA Microgrid concept. minimum generation levels, micro-generation scheduling is

not necessarily straightforward for light loads in islanding.3.5 Other Projects Secondly, if a uniform power electronics interface is not

used, accommodating the varying response rates of bothA number of other Canadian distributed generation micro-generation and energy storage can be challenging.

projects, while not strictly 'Microgrids', are of significancein the development of Microgrid technology. 4.2 Hachinohe Project

The Ramea wind-diesel project, undertaken by The New Energy and Industrial TechnologyNewfoundland Labrador Hydro [13], investigates the Development Organization (NEDO) in Japan has startedautonomous control of an islanded grid comprising 1.2MW three demonstrations as part of the "the Regional Powerpeak load, 395kW of wind turbines with diesel generation, Grid with Renewable Energy Resources Project". Theseall centrally controlled. projects qualify for the national program because they have

a significant share of renewable energy in a microgrid. TheSherbrooke Hydro utilizes financial incentives for sites are in Hachinohe, Aichi and Kyoto.

customers to employ their back-up generation to reduce Y tit network 40kW loadpeak loads [13], a potential feature of Microgrid systems. lOW PV

PX i ,KonakanoThe Fortis-Alberta scheme connects 3.8MW of wind Junior

generation and 3MW of hydro-generation on a 25kV building' 360kWV GQkW 'loadfeeder, and at certain times of year the feeder changes from G 8kW wind turbinea net load to a net generator. While the capabilities 2W wind 10kW P KPG 'onakanodeveloped for the Fortis-Alberta feeder are thus of interest turbines _ ementaYto Microgrid engineers, the system is not permitted to 4k ldisland - micro-generation must disconnect if a fault occurs Clenta! Cntrol System IrkW P`V

on the feeder. KoyoJunior

4 Asian Microgrids Bia engines Wl -g i g l Ble-gaS engineS ~~~~~~~~~~~~~~8kVV win,[email protected] Shimizu's Microgrid 50kW 100kW Elementary

ility network ies Sewge at lad

22kW gas G 90kW gas engine Figure 6. Hachinohe Systemengine T (powers shown are contracted values)

27VV as turbine RI|IEF. ..... 350VV asengine2_kW gas turbine G PE 350kW gas engie This project, a collaboration between Hachinohe20KW lea3d'acdPE PE1 X 400kh city, Mitsubishi Research Institute and Mitsubishi Electric

banttery T m n T NiMH battery [16], utilizes a private 6kV feeder connecting four schools,the local city hall, an office building of the regional water

I0kP PERX uEtrapaciEor supply and a sewage treatment facility. A variety ofscanliTmalr consumer loads are joined with PV, wind turbines, batteryscalemicro9id C _ntralCotrol Syste energy storage and three large gas engines fed by sewage

and waste gas by-product. Exhaust heat from the gas-Figure 5. Shimizu Extended Microgrid engines is reused in the sewage fermentation process. The

TOBU drainage facility (treatment plant) system isThe Shimizu Corporation has built both a pilot and a controlled by an information exchange network. The

larger scale Microgrid at its research labs in Tokyo, Japan. system is essentially a type A system, with a fast controllerThe first phase, a smaller-scale Microgrid, was constructed at one site creating a fast-acting generation / storage facilityto support company loads in Shimizu's laboratories and which ensures system stability despite additional, thoughwas used to evaluate their 'optimum operation planning much smaller, micro-generation.system', i.e. type A Microgrid control [14, 15]. This wasthen upgraded during 2006 into a larger Microgrid by the 4.3 Kyoto Eco-Energy Projectaddition of two additional gas engines (90kW and 350kW)as well as extra storage in the form of a 400kWh NiMH This project is located in Kyotango city north ofbattery (5OkWx8h, with 200kW inverter) and an 100kW Kyoto [17]. A control centre communicates with the micro-ultracapacitor (4 second rating). The Shimizu research generation units over a variety of telecommunications


infrastructure, and the existing utility network to control fed through a DC:DC converter. This gives fulldemand and supply, making this a type A Microgrid. Uniterruptible Power Supply (UPS) back-up to part of theBiogas is generated from (food) waste. system and supplies some DC loads. The premium quality

supply A is non-interrupted, and performs voltageUUiltynetwork Kowakj substation 55W load waveform correction [19]. When the utility grid has a

PE G1iwn50k momentary voltage drop and outage, the outage time fori__ asaka,tuebine high quality B is less than 15 is. High quality B issubstation subdivided by differences during utility grid outages.

citra 1MW Of When a utility grid has an outage, high quality B1 is

PE0kW - Se<:Ou'lVvWbacked up by storage. High quality B2 is backed up bylOkW ybattery distributed power. High quality B3 is not backed up.

PV RE FO 250kW CFC Utility networklOOkW

Cl High powr qualiyG 5x$OkW biogas engines DR loads (B3)3OkW

30kWN Bio povier-plant Wlai:PV powewerpantCl High powe quahty

PV ~~~~~central control systemj qaityOloads) odsB)lkFigure 7. Kyotango project -_______

Cmentra C ontro Ssterfi* _ r n ~~~~~~~~~~~~~~~~~~~~PV

4.4 Aichi Project P Pium' power

Exhdt-Budding Q ~ PE ADG AdCAC quality loads (A)g_ ti1ty network EXhibition Building gnignl P

3301tWPV PE FO270kW MC Wg TO Load 20kW

33OkW PV PE 205_M ga

25kW OFOl E -PE-C,G Mgui3OO l, systemFuel Ce I~ ~ ~ ~ ~ FelCl igr .SediPojc:Mltpepwe ultysplFuel Cell iElrkubitFuel Cielg L4.6 Hsinchiang, China

Figure 8. Aichi MicrogridUtility network Q|b 1 00kW genset

This Microgrid project was undertaken for the 2005 380V feederAichi EXPO by Chubu Electric Power, Toyota Motor Corp, 40 homes, 3 businesses_ 80kWNTT Facilities, Japanese NGK Insulators, Mitsubishi (90kW peak load, night) batterHeavy Industries, Kyocera and Aichi Prefecture [16, 18]. 60kWRenewable generation, battery energy storage and fuel cells PV(solid-oxide, molten carbon and phosphoric acid) were Figure 10. Hsinchiang Chinaintegrated. The MCFC and SOFC act as base-loadgeneration. Garbage fermentation and gasification act as In addition to its other Microgrids research,energy input to the MCFC. A by-product of employing the Mitsubishi Electric has also installed a small Microgrid infuel cells was refrigeration of cold water for air Hsinchiang China [20]. The peak load of 90kW can beconditioning. A common central interconnection console supplied by a combination of the distribution network, PV,allows energy management to be simplified, by selecting battery and genset operation.which systems to run, making this a type A system. Thesystem was moved to Central Japan Airport City. 5 European Microgrids

4.5 Sendai Project 5.1 KythnosThe Sendai system is presently under-construction While not strictly speaking a Microgrid, in so far as it

[16] and is planned to include substantial PV micro- operates in islanded mode only, the autonomous system ongeneration, gas engines, a molten carbon fuel cell, as well Kythnos in the Aegen Sea has played a significant role inas series and shunt power compensation devices, the formation of the thinking in European MicrogridSignificant is the use of series compensation devices projects [2,3].(Dynamic Voltage Restorers or DVRs) to compensate forvoltage sags to some loads, and the use of an AC:DC:AC The stand-alone system is located 4km from theinverter ('Integrated Power System') with battery backup nearest utility feeder. It has taken a number of forms [21,

22] topologically and has been used as a research tool.


Control is by means of real power (P) vs. frequency (f ) Ut netand reactive power (Q) vs. voltage (V) droop lines, though Utlity networkon a single-phase basis. The single-phase nature of the 1system places limits on the available bandwidth of the Pocpower signals and has led to the suggestion that input and 80kW 71kVApeakoutput control signals be interchanged, i.e. inverter output Gicrturbine consumer8Woadsfrequency and voltage be controlled in response tomeasured power signals [23]. The system is essentially a Figure 12. EDP Frielas Feederprototype for the type B Microgrid control philosophy.

I ~~~~~5.4CESIPE1Utility ne| l,kW

PE PE10k`W 1 kVABattery 5VA peakEnergy diesel householdStorage get loads 800 kVA11kW PV

, jI ! (. ¢| I, PPE lT 1kW.10kW sterIiinFigure 11. Kythnos Autonomous Network engine G PE

a_ LiL G ~~~~~7kW15OkWMC ~~~~~~~~~~~~~diesel5.2 Labein Experimental Centre FuelCell

HE A windUtility network 2x125OkVA I10kW e== tW l| |l{<2D~~~~~~~~~~~~~~~~~~2kW50kW resistive load150kW resistive load 100kW

PE 36kVA reactive load flywhee PXOOkW36kVA react'fve load..................le da

1925Ah microturb4ne

36kWPV 1 Line Control room loads3phase _PE 6kW CAme Contro 1VAprogrammable

55kWdi8esel 2 lultracap Figure 15. CESI Test Facilitygenerator lZ51V

55kW diesel flywheel The CESI network in Milan [26] was developed forgenerator 6kW wind the testing of distributed generation technologies. The test

5m'c-t.' REP i ]rbin system will be used as part of the More-Microgrids projectmicrotutbine [3] to characterize the performance of the large variety ofFigure 13. Labein Microgrid distributed generation and local control in the face of

network disturbances and during islanded mode to evaluateThe Labein Research Institute in Spain has put power quality. It is also intended to test power line-carrier

together a test system for distributed generation and communication for partial type A microgrid operation.Microgrid research [3]. It is fed by two 125OkVAtransformers. The system is intended as a test bed for both 5.5 Continuon Holiday Parkdecentralised and centralized control schemes and thereforeutilizes a degree of reconfigurability. Utility 200 holiday homes

no- or-1lk il400kVA 400P5.3 EDP Feeder C_ 0 ~~Poc E t_

The Portuguese electricity utility EDP is in theprocess of upgrading the far end section of a small200kVA, 400V 3-phase 4-wire, commercial radial feeder C,Ol _ PEin the village of Frielas, a suburb of Lisbon [24,25] in order PEto undertake Microgrid studies. The use of only one sourceof micro-generation, with a capacity in excess of the ~eeg 1k ekPmaximum Microgrid load simplifies the microgrid control storgeproblem. This forms a special class of the type B Figure 14. Continuon Holiday Park Microgrid simplifiedMicrogrid. diagram - PV distributed among homes


Together with EMforce and Germanos, Continuon is Pentadyne flywheel forms the energy storage. Expansion ofupgrading a holiday park it runs in the Netherlands into a the Microgrid is planned with two CHP units rated at 9kWMicrogrid [3]. At present the park consists of 200 holiday and 5.5kW (electrical). The total on-site load variescottages, many of which have grid-connected between about 80kW to 230kW. The building's 60kWphotovoltaics. The total 315kW of installed photovoltaics ventilation and 48kW boiler loads are controllable. Thisexceeds the load during the day. Plans are underway to add Microgrid's structure is still under development though ata central battery energy storage unit and power electronic present the combination of a large central store makes it aconverter along with a central microgrid controller to allow type B Microgrid. The addition of centrally controllableload control and resynchronization. The Microgrid is thus a loads would however introduce type A elements.type B.

The 'Am Steinweg' estate with 400 inhabitants in5.6 Demotec Stutensee, Germany is another of MVV's Microgrid

projects. The low voltage (LV) closed ring structure hasUtlity 400kVA 5kPwind 28kW (electrical) of CHP installed and PV installations

rbine simrulator with a total peak power of 35kW. In addition 880Ah ofkVA MG Set \ )lead-acid battery are interfaced through a bi-directional

kV 15Jtconverter. MVV is using this installation to trial the use oftheir power management system in this type A system.1 75kVA_ PV-Battery

LP subsysem Lastly MVV is constructing a Microgrid inMannheim-Wallstadt. The installed microgeneration is atpresent only 30kW peak of PV, but substantial further

80kVAMG set 4 | Lliil_ 'expansion of the microgeneration is planned.

2OkVA diesel G P P PV-Battery- 6 Conclusionsgenlset _ di.esel sub-

3OkVA diesel gen G Many systems have been constructed to evaluate theconcept of enhanced micro-generation. Colloquially called'Microgrids', this has become a 'buzz-word' that covers a

great many types of system. The majority of such systemsPV Inverte t s P Ehave opted for either a virtual or a physical 'prime mover'

PE _; Solar-Battery topology. In part this reflects the on-going development of_ Xi s,tSm Microgrids from distributed generation systems and the

PV-Balte 1 X1Supervisory nature of these projects as 'hardware demonstrators'. Inl monAonnlu1gl -rid part it reflects the usefulness of a single large prime-mover

connectionConnection unt bredktr located near the point-of-coupling (PoC) with the utilityBatbery banks! W PE to unwersity contol E being able to dominate the system behaviour at the PoC.virual baftery labs

A distributed approach throws up more challenges forthe system design - PoC behaviour is no longer dictated by

The Demotec facility at ISET [27] in Kassel a single unit (physical or virtual). However, in principle,Germany has been used extensively to develop the Microgrid is less reliant on any one piece of hardware

methodologies for the control of distributed generation. It and extending the Microgrid would not require a change tothe hardware of any of the already installed systemwas also used in the first EC Microgrids project [2] to e of y y y

elemnts Ofcourse software changes may still beevaluate central control and unit control strategies.elmnsOfcuesotae hngs ay tilbnecessary to ensure that design constraints of the modified

5.7 MVV Energie Projects system (e.g. feeder voltage limits) are still observed.

MVV in Germany is presently piloting a number of We look forward to the results of on-going field trialsMicrogrid Projects [3]. The substation network connected to address these and other issues in the development of thisto the MVV headquarters building in Mannheim Germany exciting field.has been identified by MVV as a site to investigateMicrogrids [28]. The proposed system includes residential References:and commercial units and loads: the MVV headquarters andan adjacent apartment block which are fed from a single [1] R.H. Lasseter, "Microgrids", IEEE Powersubstation. A 4.7kW PEM fuel cell and 3.8kW of PV form Engineering Society Winter Meeting, 2001, vol. 1, pp. 146-the installed on-site micro-generation [3]. A 120kW g

Authorized licensed use limited to: Inha University. Downloaded on August 17,2010 at 01:06:17 UTC from IEEE Xplore. Restrictions apply.

[2] European Research Project "Microgrids", [17] "Garbage becomes electricity at state-of-the-art plant",http://microgrids.power.ece.ntua.gr, 2003-5. New Energy and Industrial Technology Development

Organization (NEDO),[3] European Research Project "More-Microgrids", http://www.nedo.gojp/kankobutsu/pamphlets/kouhou/fy20http://microgrids.power.ece.ntua.gr, 2006-9. 04/27_28.pdf

[4] "Highly Distributed Power Systems" UK Research [18] "New Energy on-site research at EXPO 2005 Aichi,Council Supergen project grant GR/T28836/01, 2005-9. Japan", http://www.ntt.co.jp/csr_e/kankyo/03_03.html,

NTT on-line newsletter.[5] "UK-Microgrids", UK Research Council EPSRC grantEP/C00177X/1, 2005-8. [19] K.Hirose et al, "Study on Field Demonstration of

Multiple Power Quality Levels System in Sendai,[6] S.Morozumi, "Technology Development For Grid- International Telecommunications Energy Conference,Connection Issues", Renewable Energy 2006, Chiba, September 2006Japan, Oct. 2006

[20] T. Goda, "Microgrid Research at Mistubishi",[7] US Department of Energy Electricity Distribution California Energy Commission symposium, JuneProgramme, "Advanced Distribution Technologies and 2005,http://www.energy.ca.gov/pier/esi/documents/2005-Operating Concepts - Microgrids", http:// 06-17_symposium/GODA_2005-06-17.PDFwww.electricdistribution.ctc .com/microgrids .htm

[21] P. Strauss and A. Engler, "AC Coupled PV Systems[8] International Journal of Distributed Energy Resources, and Microgrids - State of the Art and Future Trends", 3rdMicrogrids Special Issue 2006/7, ISSN 1614-7138, editor World Conf. on Photovoltaic Energy Conversion, Japan,N Hatziargyriou 2003, pp. 2129-2134.

[9] A.L Dimeas and N Hatziargyriou, "Operation of a [22] J. Schmidt, P. Strauss and P. Schweizer-Ries, "MoreMulti-agent system for microgrid control", IEEE Trans. than a Light-bulb", Renewable Energy World, July-AugustPower Systems, vol. 20, no. 3, Aug. 2005, pp. 1447-55 2003, pp. 192-199

[10] P. Piagi and R.H. Lasseter, "Autonomous Control of [23] A. Engler, C. Hardt, P. Strauss and M. Vandenbergh,Microgrids", IEEE PES Meeting, Montreal, 2006. "Parallel operation of generations for stand-alone single-

phase hybrid system", EPVSEC Conference, Munich[11] R.H. Lasseter and P. Piagi, "Control and Design of Germany, 2001.Microgrid Components", Final project report, PSERCpublication 06-03, http://certs.aeptechlab.com/ [24] A. Amorim, A.L. Cardoso, J. Oyarzabal and N. Melo,

"Analysis of the Connection of a Microturbine to a Low[12] J. Lynch, "Update on Mad River Microgrid and Voltage Grid", International Conference on Future PowerRelated Activities", CERTS Microgrid Symposium, June Systems, 200517, 2005.

[25] J. Oyarzabal, F. Fresquet, A. Amorim and A.[13] C. Abbey, F. Katiraei, C. Brothers, L. Dignard-Bailey Androutsos, "Large Scale Integration of Micro-Generationand G. Joos, "Integration of Distributed Generation and to Low Voltage Grids", DII Deliverable Report, EuropeanWind Energy in Canada", IEEE Power Engineering Commission Framework V Microgrids project.Society Meeting, June 2006

[26] A. Invernizzi, "Technologies to Innovate Distribution[14] J. Baba, S. Suzuki, S. Numata, T. Yonezu, S. Networks with DG", IEA Workshop on Electricity T&D,Kusagawa, A. Denda, T. Nitta and E. Masada, "Combined Session V - Integrated Distributed and IntermittentPower Supply Method for Microgrid by the Use of Several Sources, Paris Nov. 2004.types of Distributed Power Generation systems", EuropeanConf. on Power Electronics and Applications (EPE), 2005. [27] T. Degner, and P Strauss, "Laboratory for Distributed

Generation", EC Project DISPOWER , Project Highlight[15] A. Denda, "Shimizu's microgrid research activities", document no. 3, http:// www.iset.uni-kassel.de/Symposium on Microgrids, Montreal, June 2006.

[28] "ISET Institutionsbericht 2005 - Erfolge und[16] 5. Morozumi, "Overview of Microgrid Research and Perspektive", 2005 Yearly Report of the Institute for SolarDevelopment Activities in Japan", International Energy Technology, Kassel, Germany.Symposium on Microgrids, Montreal, June 2006.


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Real-World Micro Grids- An Overview