Dispatch, Control Strategies and Emissions for Isolated Wind-Diesel ...

International Journal of Innovative Technology and Exploring Engineering (IJITEE)ISSN: 2278-3075, Volume-2, Issue-6, May 2013Dispatch, Control Strategies and Emissions forIsolated Wind-Diesel Hybrid Power SystemBindu U. Kansara, B.R. ParekhAbstract— Depleting oil reserves and the growing concerns ofglobal warming, have made it compulsory to seek alternative inform of environment friendly technologies like renewable energysources. The advantage of hybrid power systems is thecombination of the continuously available diesel power andlocally available, pollution-free wind energy. With theWind-Diesel hybrid power system, the annual diesel fuelconsumption can be reduced and, at the same time, the level ofpollution can be minimized. A proper control and dispatchstrategy has to be developed to take full advantage of the windenergy during the periods of time it is available and to minimizediesel fuel consumption. The paper presents two dispatchstrategies (i) load following and (ii) Cycle charging along withdifferent system controls. For the proposed system, load followingdispatch strategy along with its system control performs betterthan the cycle charging strategy.Index Terms— Wind Turbine, Diesel Generator, DistributedGeneration, HOMERI. INTRODUCTIONOne of the most recognized terms in today’s electricitymarket is decentralization of energy sources. To realize thepotential of distribution generation, generation and load mustbe taken as a subsystem. This system may use anycombination of generation, load and storage technologies andcan operate in grid connected mode or autonomous mode.Some examples of micropower system or microgrid aresolar-battery serving a remote load, wind-diesel systemserving an isolated village, a grid connected natural gasmicroturbine providing heat to a factory. Micropower systemconsists of electric and thermal load, and any combination ofphotovoltaic modules (PV), wind turbine, small hydro,biomass power generation, microturbines, fuel cells,reciprocating engine generators, batteries and hydrogenstorage.The analysis and design of micropower system [1] ischallenging due to large number of design options anduncertainty in key parameters such as load size and future fuelprice. Renewable energy sources add further complexitybecause the output may be intermittent, seasonal andnondispatchable and the availability is uncertain. The work isa technical, environmental and economic feasibility study[2,3] and dispatch strategies to manage the load demand of ahybrid generating system, composed of wind, diesel andbattery interfaces feeding a customer with high reliabilityrequirements of electric supply.Penetration of DG across the country has yet not reached thesignificant levels. These emerging technologies have loweremission and potential to have lower cost. A better way torealize the potential of distributed generation is to take asystem approach where load and generation acts as asubsystem called “microgrid” [4]. This is a decentralized andbidirectional pattern permits electricity import from the gridand electricity export to the grid. A plant that produceselectricity less than 500 kW comes under micro generationtechnologies. Microgrid sources can produce electricalenergy and thermal energy both. Hence, the penetration ofdistributed energy resources both at low voltages and mediumvoltages in utility have been increased in developed countrieslike USA, Canada, Japan and Germany. Computer simulationis an increasingly popular tool for determining the mostsuitable hybrid energy system type, design and control for anisolated community or a cluster of villages. This paperpresents the system control combined dispatch strategies, toachieve better performance of wind-diesel system. The mainpurpose of the control system proposed here is to reduce theparticipation of the diesel generator in the electricitygeneration process, taking the maximum advantage of therenewable sources available. The overall load dispatchscenario is controlled by the availability of renewable power,total system load demand, diesel generator operationalconstraints and the appropriate management of battery bank.The incorporation of a battery bank makes the controloperation more practical.II. SYSTEM SCHEMATIC AND COMPONENTSThe ability to generate electricity is a building block ofmodern society. The utilization of wind turbines to produceelectricity is practiced for over hundred years. Similarly,diesel engines have been a technology to produce energysince 1940s. However, the field of engineering concernedwith the coupling of Wind-Diesel systems have just begunrecently [6]. The following schematic represents basicWind-Diesel hybrid system. Hybrid power systemincorporates more than one piece of equipment for electricityproduction as well as storage, power conditioningcomponents and system controls. The system consists of twodiesel generators alongwith a wind turbine connected to ACbus side of the network. HOMER power optimizationsoftware by NREL is used to simulate and analyze the hybridsystems.Manuscript received on May, 2013.Prof. Bindu U. Kansara, Electrical Engineering Department, SardarPatel University, A.D. Patel Institute of Technology, New Vidyanagar,India.Dr. B.R. Parekh, Head, Electrical Engineering Department, Sardar PatelUniversity, BVM Engineering College, India.152

Dispatch, Control Strategies and Emissions for Isolated Wind-Diesel Hybrid Power Systemcombination to its rated capacity, or as close as possiblewithout causing excess electricity.If a setpoint state of charge is applied to the cycle chargingstrategy, then when the battery state of charge is below thesetpoint and the battery was not discharging in the previoustime step, HOMER will avoid discharging the battery in thistime step. A generator will likely be called upon to serve theprimary load and produce excess electricity to charge thebattery bank. So once the system starts charging the batterybank it continues to do so until it reaches the setpoint state ofcharge.C. System Controls :Multiple generators can operate simultaneously, withminimum renewable energy fractions (MRF) considered =0% and 20%, annual interest rate = 6%, plant working lifespan = 20 years, diesel price =0.8$/L, wind speed = 0, 4.5 and5.5 m/sV. RESULTS AND DISCUSSIONThe system shown in figure 4 is simulated for two differentdispatch strategies with the system controls. Table 1 showsthe comparison of load following and cycle charging dispatchstrategies.The system is simulated for load following and cycle chargingwith SOC 80%, the analysis is carried out consideringtechnical, electrical and environmental aspects. With theproposed system control and dispatch strategies, Table 1shows the performance of the system with load followingstrategy is better than that of cycle charging dispatch.[6] Shahid S. M., El-Amin I, Ahmed F., “Potential of Off-GridWind/Diesel hybrid System for Electrification of a remote Settlementin Saudi Arabia” Wind Engineering, 28 (5) , 621-628, 2004.[7] Frye Jack A. “Performance Objective Design of a Wind-Diesel HybridEnergy System for Scott Base, Antarctica”, Master’s Thesis, 2006.[8] http://www.academia.edu/1485012/Dispatch_Strategy_and_Model_for_Hybrid_Photovoltaic_and_Trigeneration_Power_Systemsaccessed on 12 March, 2013[9] J.K. Kaldellis, An integrated model for performance simulation ofhybrid wind–diesel systems Renewable Energy 32 (2007) 1544–156science direct[10] Survey on Microgrid Control Strategies Wei Huanga, Miao Lua*, LiZhangb elsevierProf. Bindu U. Kansara is with Department of Electrical Engineering, A.D.Patel Institute of Technology, New Vallabh Vidyanagar. She has completedher Bachelor and Master degree in Electrical Engineering from BirlaVishvakarma College of Engineering, Gujarat, India. She is currentlypursuing Ph.D. Her research interest includes Microgrid, DistributedGeneration and Power System Operation and Control, Renewable EnergyResources.Dr. B. R. Parekh is Professor and Head of Department of ElectricalEngineering, BVM Engineering College, Vallabh Vidyanagar, Gujarat,India. He has completed his BE and ME in Power System. He has completedhis Ph.D. from IIT, Bombay with specialization in power system. He haspublished number of papers in national and international journals. Hisresearch interest includes HVDC transmission systems, Power SystemOperation and Control.VI. CONCLUSIONThe results of isolated Wind-diesel hybrid system usingHOMER modeling shows that if, cost summary, cash flowsummary, electrical production or emissions and cost of windturbine, battery and converter us considered as a whole, loadfollowing dispatch strategy is far better than cycle chargingdispatch strategy. Considering economic, technical andenvironmental aspects for both the strategies, Load followingstrategy is better in cases where renewable penetration is moreand cycle charging is effective in cases where renewableenergy penetration is less. For this hybrid wind-diesel system,load following dispatch strategy gives better performance interms of Net Present Cost (NPC), Cost of Energy (COE),renewable fraction and GHG (Green House Gases) emissions.REFERENCES[1] Rocha M. da., Landa Noronha G., Paula Cardoso A. ,et. al. “Feasibilitystudy for Hybrid Electric Generating with Wind-Diesel and GridResources “ RIO 9 – World Climate and Energy Event , 17-19 March,2009, Brazil[2] Manwel J. F., McGowan J. G., Abdulwahid U., “SimplifiedPerformance model for Hybrid Wind-diesel System” RenewableEnergy Laboratory, MA, USA.[3] BJindal A.K., Gole A.M., Muthumuni D., “Modeling and PerformanceAnalysis of an Integrated Wind/Diesel Power System for Off GridLocations,” 15 th National Power System Conference (NPSC), IITBombay, December 2008.[4] Lasseter R. H., Paigi P. “Microgrid : A Conceptual Solution”PESC’04, Germany, 20-25 June 2004[5] Getting Started Guide for HOMER Version 2.1, April 2005155

International Journal of Innovative Technology and Exploring Engineering (IJITEE)ISSN: 2278-3075, Volume-2, Issue-6, May 2013StartObtain Wind Speed Data for a particular locationEnter load data (i) Daily Profile and (ii) Seasonal ProfileSelect suitable sizes of Wind Turbine, Diesel Generator, Battery and ConvertorApply system control and dispatch strategyIsolated Wind – Diesel Hybrid SystemLoad FollowingCycle ChargingAnalyze the impacts of both dispatch strategies in terms ofEnvironmental, Technical and Economic AspectsParametersStopFigure 5 Flowchart of the Proposed SystemDispatch StrategiesLoad FollowingCycle ChargingTotal net present cost (NPC) $ 5,732,866 $ 5,812,497Levelized cost of energy (COE) $ 0.574/kWh $ 0.582/kWhOperating cost $ 268,346/yr $ 274,576/yrWind turbines 8,325,531 kWh/yr - 97% 8,325,531 96%Generator 1 73,499 kWh/yr -1% 70,729 1%Generator 2 215,000 kWh/yr - 2% 258,679 3%Renewable fraction 0.629 0.578Carbon dioxide 334,355 kg/yr 359,157 kg/yrCarbon monoxide 817 kg/yr 878 kg/yrUnburned hydocarbons 90.5 kg/yr 97.3 kg/yrParticulate matter 61.6 kg/yr 66.2 kg/yrSulfur dioxide 672 kg/yr 721 kg/yrNitrogen oxides 7,288 kg/yr 7,836 kg/yrTable : 1 Comparison of dispatch strategies for Wind-Diesel-Battery System156