Research On Optimal Sizing Of Wind/Solar/Battery (/Diesel Generator) Microgrid

Microgrids play an important role in solving power supply problems in remoteareas which are not connected to the grid, as well as improving the reliability andquality of power supply in the areas which are connected to the grid. Optimal sizingof microgrids is the most important issue to be resolved in the design phase that theoptimal schemes will directly determine the security and economic benefits ofmicrogrids. The paper focuses on the optimal sizing issues of stand-alonewind/solar/battery/diesel generator microgrids and grid-connected wind/solar/batterymicrogrids. Furthermore, the optimization software is designed and implemented. Themain works are summarized as follows:1) The quasi-steady state models of wind turbine, photovoltaic array, dieselgenerator, and battery energy storage system, as well as the economic model ofmicrogrids are presented. The characteristics and models of wind energy and solarenergy are introduced.2) Operation strategies of stand-alone wind/solar/battery/diesel generatormicrogrids are studied and analyzed. Based on the classification of control methods ofdiesel generator and battery energy storage system, the operation strategies ofstand-alone wind/solar/battery/diesel generator microgrids are analyzed in the details.Based on the operation problem of an actual stand-alone wind/solar/battery/dieselgenerator island microgrid, the lifetime assessment method considering SOC isanalyzed, and the optimization of operation strategy parameters is discussedconsidering the characteristics of lead-acid battery energy storage system. Therelationship between power supply cost and life loss of battery energy storage systemis analyzed.3) Optimal sizing method of stand-alone wind/solar/battery/diesel generatormicrogrids is studied. Based on the analysis of operation strategies of stand-alonewind/solar/battery/diesel generator microgrids, the type and capacity of distributedgenerations are chosen as optimization variables of sizing, as well as the type andparameters of operation strategies are added as optimization variables of strategies injoint optimization process. Taking the economy and environmental protection as the goals, the optimal sizing schemes under different operation strategies are analyzed tostudy the relationship between operation strategies and optimal sizing schemes.4) Optimal sizing method of grid-connected wind/solar/battery microgrids isstudied. The self-balancing rate is proposed and the power volatility ininterconnection line, the proportion of self-consumption, and other indicators areconsidered. Combined with the optimal operation and optimal sizing methods, therelationship between power supply ability and economy is analyzed from the view ofuser benefits to obtain the optimal schemes of grid-connected wind/solar/batterymicrogrids under different self-balancing rates. The influences on optimal schemes ofdifferent electricity prices and transferable load conditions are analyzed.5) Based on theoretical research, the architecture, general processes, and keyfunctions of microgrid optimization software are summarized and analyzed. Amicrogrid optimization software is designed and implemented to improve thefunctional framework and architecture of existing microgrid optimization software.