Project of a Pilot-Microgrid connected to the Main Grid

Blucher ProceedingsVIII Encontro Cientıfico de Fısica Aplicada Blucher

Project of a Pilot-Microgrid connected to theMain Grid

Danilo P. e Silva1∗, Daniel Carletti1,Tiago M. de Christo1,Renan C. Basoni1, Macello D. Queiroz1, Igor O. Barbosa1,

Marcos T. D. Orlando2, Jussara F. Fardin1

1Power Eletronics and Electric Drive Laboratory

Federal University of Espırito Santo, Vitoria, ES, Brazil2Physics Department, Federal University of Espırito Santo, Vitoria, ES, Brazil

∗[email protected]

Abstract

The interest on renewable sources of energy and sustainable energy managementhas driven a lot of countries to develop projects and researches about this subject.The microgrid is one of the approaches within the concept of Smart Grids that hasbeen studied through recent years. This paper describes the recent state of theresearches about microgrids in Federal University of Espırito Santo, and presentsthe pilot project of a microgrid developed in this university. The microgrid is con-nected to the electrical main grid with wind and solar photovoltaic resources andwith a control system for studies on energy management, electrical systems protec-tion, multi-objective optimization and virtual synchronous generation

1 IntroductionMicrogrids, characterized by off-grid sys-tems, have existed for decades to supplyremote regions, which do not have con-ventional electrical distribution grid. Tomeet sustainable development, technolo-gies based on wind energy, solar energy,biomass and fuel cell have become prior-ity in microgrid integration, driving sev-eral countries to adopt policies to encour-age the use of renewable energy such astariff allowance, green/sustainable certifi-cates, credit for investments and govern-

mental programs.In European Union in 2014, renew-

able energy generation corresponded to25,5% of the total energy generated [1].From this percentage, about 18% ofthe renewable energy generated corre-sponded to solar photovoltaic and windenergy.

In Brazil, Normative Resolution482/2015 from the Electrical Energy Na-tional Agency (ANEEL), which regulatesdistributed mini and micro-generation, isa great incentive to electric power gener-ation from renewable sources. This reso-

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lution created the Electrical Energy Com-pensation System, allowing consumersto install small generators in his unit(such as photovoltaic panels, wind micro-turbines, and others) and exchange en-ergy with the power distribution companyin order to reduce the value of his electricbill [2].

In this context, the concept of mi-crogrids arises [3], [4] which is an ag-gregation of loads and renewable andnon-renewable micro-generations operat-ing like an off-grid system or grid-tie con-trolled system, locally providing powerand heat. For the electrical power sys-tem, the microgrid can be seen as a sin-gle cell and can be considered as a vari-able single load, or as a variable electricalenergy source. Microgrids manages andsupply energy for houses, industrial park,shopping centers, commercial buildings,etc. For internal consumers, a microgridbrings great benefits, such as reduction oftransmission costs and losses, energy sup-ply reliability, power reserve, decrease inpeak demand, and others.

This article was structured and pre-sented next: Section 2 describes theresearch projects about microgrids ofthe Electrical Engineering Departmentof Federal University of Espırito Santo(UFES). The description of the micro-grid pilot project is discussed in section3, in section 4 the conclusions with fur-ther steps for the research and in section 5the acknowledgements.

2 Microgrid researchesat UFES

Universities have been strengthening theirmicrogrids and Smart Grid researchgroups Smart Grid [5] equipping labora-tories, purchasing or developing software

and building pilot projects for tests andperformance analysis. Federal Univer-sity of Santa Catarina (UFSC) in partner-ship with Tractebel Energia have an intel-ligent microgrid laboratory and is devel-oping a hybrid microgrid AC/DC with so-lar photovoltaic generation, wind genera-tion and energy storage [6]. The Center ofStudies in Regulation and Energy Quality(ENERQ) of the University of Sao Paulo(USP) develops researches about SmartGrids, distributed generation and micro-generation. Federal University of EspıritoSanto (UFES) also proposed to partici-pate with investigations the new reality ofthe energy system, collaborating with re-sults, analysis and human resources for-mation.

The beginning of the investigation re-sulted in a doctorate, which was con-cluded in 2010 [7] and one of its contri-butions was an irradiance and temperaturemeasurement estimator for a photovoltaicsystem. The continuity of the researchevaluates the impact of distributed gen-eration in decision-making processes oftechnical planning of the electrical energydistribution company [8] and the projectand development of a microgrid, includ-ing the concept of Smart Grid, for theBrazilian Station in Antarctica [9]. In hismaster’s degree [10] Azini developed asoftware for non-intrusive monitoring ofresidential loads, which will be includedin the pilot project. The application of avirtual synchronous generator to controlinverters in distributed generation is alsoone search object [11].

3 Pilot ProjectThe Microgrid pilot Project was moti-vated on recent interest of the scientificcommunity of UFES. Real data collection

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and the possibility of implementation ofmanagement of a real microgrid are fun-damental elements for the continuity ofthis research line. One of the main objec-tives of microgrid management is energycost reduction along with reduction of en-vironmental impacts caused by the pro-duction and transmission of electric en-ergy through conventional grids.

The pilot project will be connectedto the conventional grid, owning windand solar photovoltaic sources and con-trollable loads managed by a Supervisory,Control and Data Acquisition System(SCADA). Figure 1 shows the schematicdiagram of the pilot microgrid.

The connection point is the placewhere the microgrid gets connected toUFES’ grid, which is tied to the powerdistribution company. The point of com-mon coupling (PCC) is an electrical panelwhich function is to interconnect powersources, loads and other equipment to themicrogrid in a common bus and makingeach one’s electrical protection. PCC hasvoltage and current sensors for data ac-quisition through SCADA.

Solar photovoltaic generation if com-posed of 6 PV panels of 250 Wp each,model AC-250P/156-60S of Axitec, onefrequency inverter of 2,0 kW, output volt-age of 220 V, model Fronius Galvo 1.1-5and on AC protection panel. The inverterhas the function of anti-islanding protec-tion, not allowing the PV generation tooperate in the off-grid mode. Figure 2shows the PV modules installed.

The wind generator is composed ofthe wind turbine with diameter of 2,46m,power of 1,0 kW, output voltage of 220Volts model GERAR246 of Enersud. Inthe set of wind generator, there is the fre-quency inverter with power of 1,5 kW,voltage of 220V, model Ningbo GinlongTechnologies CO.LTD GCI-1.5kW, the

damping resistor to dissipate the excessenergy of the inverter and the controllerthat protects the wind system and inter-connects all the equipment. The inverterhas the function of anti-islanding protec-tion, not allowing the wind generation tooperate in the off-grid mode. Figure 3shows the wind generator installed.

Figure 1: Schematic diagram of the pilotproject

Figure 2: Six photovoltaic models in-stalled of 1,5 kWp

The load panel feeds six resistors of500 W each, a switched-mode power sup-ply of 400 W and a fan of 100 W. Besidesthe function of protection, this panel hascontactors, push-buttons and flags so that

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the loads are turned on independently,guaranteeing flexibility to the simulationsof demand profiles.

Figure 3: 1 kW Wind Generator

The pilot project is in assembly andtest stage. The PV and wind generationsare installed, as well as the resistive loadsand the PCC and loads panels.

The figures 4 and 5 represents the en-ergy generation of the photovoltaic andwind sources for one day, respectively.The solar generation starts at 5:45 AM,the peak generation reach 1200 W at11:45 AM and the generation finishes af-ter 5:15 PM. The wind power generated issmall because the wind speed was low onthis day. The maximum value of day is500 W at 8:00 PM. These data were ob-tained through of data acquisition systemof the solar and wind inverters.

Some equipment will be installed inthe future: the inverter emulator of dis-tributed generation, the control system

with SCADA and the battery bank withload controller.

The operating principle of the pilotproject is based on allowing the opera-tion of the wind and solar generation foras long as possible. The data of volt-age and current will also be collected tomonitor other electrical quantities (powerin kW, power factor, etc.) the loads willbe discretely controlled by a SCADA sys-tem control with interlock and sequencinglogics. Simulating different demand pro-files and evaluating the performance ofwild and solar generators will be possible.The user will be able to create his owndemand profile according to his research.Advanced resources will be added to themicrogrid management such as demandprediction, usage of superconductors tolimit short circuit currents (SFCL) andthe renewable energy offer. Algorithmsfor load escalation and battery rechargingoptimization, as well as optimization ofcosts of the energy consumed from themain grid will be evaluated. It is high-lighted that there are data on wind and so-lar incidence being collected by a weatherstation in the location where the windgenerator and PV panels are installed.

The microgrid uses conventional pro-tection based on low voltage circuitbreakers. The circuit breakers have longtime response on overcurrent, because be-sides the stage of fault detection, time formechanical opening of the circuit breakeris necessary. Considering an investigativeproposal, this micro-network provides thelaboratory environment necessary to in-vestigate a new protection device againstfaults associated with short-circuits, theresistive superconductor current limiter.The use of the fault current limiting super-conductor (SFCL) has the ability to inter-rupt fault currents immediately after theSFCL overcurrent limit is exceeded [12],

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Figure 4: Photovoltaic generation for one day

Figure 5: Wind generation for one day

[13].

4 ConclusionsThe development in research on the mi-crogird management shows a necessity ofconfronting simulated models with realvalues. The pilot project meets this trend,opening up a variety of options for re-search at UFES. Future work and researchwill address the virtual emulation of en-ergy sources through dSPACE modules,the development of frequency convertersthat allow the microgrid to operate in iso-lated mode, including batteries and loadcontroller for multi-objective optimiza-tion studies, data collection of irradianceand direction of the wind for model iden-

tification, simulation of the electrical pro-tection through searches with current lim-iting superconductors.

5 AcknowledgmentsThe authors thank a Foundation for Re-search and Innovation Support of EspıritoSanto (FAPES) project number 67666027for financial support.

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[10] Fardin, J. F.; Salles, E. O. T. Soft-ware for Nonintrusive MonitoringResidential Loads with two Dif-ferent Approaches. In: WorkIn-nova: Denmark-South AmericaWorkshop on Sustainable Tech-nologies, Research and Innovation.,2012, Vitoria. WorkInnova, 2012.

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[13] Gannamani, N. K., Jagadesh,G.,Optimal Performance of Super-conducting Fault Current LimiterApplied to Micro Grid System, In-ternational Journal of Power SystemOperation and Energy Management,Volume-4, Issue-1, 2013.

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Project of a Pilot-Microgrid connected to the Main Grid