| The use of energy storage system plays an essential role for the microgrid to ensure safe and stable operation and efficient renewable energy accommodation.Due to uncertainties in distributed renewable power,load and electricity market,the conventional capacity optimization method of energy storage system in microgrid is facing challenges.It is urgent to establish a novel theoretical framework for energy storage system capacity planning and operation strategy optimization,which fully considers the spatiotemporal coupling characteristics of uncertainties and autonomy constraint.This paper focuses on the capacity planning and operation strategy optimization of energy storage system in microgrid constrained by multiple uncertainties.Based on the coupling characteristics analysis and quantitative characterization of microgrid uncertainties,a quantitative evaluation indicator of microgrid autonomy based on stochastic network calculus is proposed,which is used as the constraint for capacity planning and operation strategy optimization of microgrid energy storage system.Taking full account of flexible resources and market mechanisms,the capacity coordinated optimization model for microgrid energy storage system considering multi-scale uncertainty coupling and autonomy constraint is constructed.A flexible robust optimization approach to deal with the forecast uncertainty variables in the optimal operation model of energy storage systems is introduced,and a quantitative decision method for flexible robust coordination factors to reduce the blindness of flexible robust coordination factor decision-making is further derived.This paper reveals and utilizes the optimization mechanism of heuristic algorithm,and proposes a multi-objective differential evolution-backtracking search algorithm and the optimal compromise scheme decision making for the specific problem to achieve the unification of efficiency and precision in capacity optimization for microgrid energy storage system.A day-ahead electricity prices decision making method based on the marginal cost principle is introduced to guide the microgrid operators to obtain the optimal capacity configuration and demand response scheme for microgrid with wind/solar/energy storage.This paper aims to construct a novel theoretical framework for capacity coordination optimization of microgrid energy storage systems,which fully considers the nature of uncertainty and autonomy constraint,and has important academic value and engineering significance.The main work is listed as follows.The first chapter introduces the purpose and significance of this paper.Combined with the characteristics of planning and optimal operation in microgrid under uncertainties,it introduces research status at home and abroad from uncertainty analysis method and optimization evaluation index of flexibility resources and optimal configuration of energy storage system for microgrid.In view of the shortcomings of the existing research,the main research contents of this paper are put forward.In the second chapter,the problem of multi-scale uncertainties coupling in microgrid is analyzed.It is pointed out that the source of multiple uncertain factors from spatial scale and the different uncertainty characteristics from time scale will have a coupling effect on the planning and optimization operation for microgrid.Then a general mathematical model of capacity optimization for microgrid energy storage system is constructed.Furthermore,the effects of multi-scale uncertainty coupling and flexible resources on capacity optimization of microgrid energy storage systems are analyzed.The third chapter introduces stochastic network calculus,and establishes envelope models that can characterize stochastic uncertainties of renewable supply and load demand,and a charging and discharging model of energy storage system.Combined with min-plus algebra,the probabilistic description of excess energy state,energy shortage state and energy balance state during the operation of microgrid is derived.Based on these probabilistic descriptions,an evaluation indicator that can quantitatively describe autonomy level of microgrid is defined.The fourth chapter considers multi-scale uncertainty coupling influence and autonomy constraint in the capacity optimization of energy storage system in grid-connected microgrid.The conventional robust optimization method is used to transform the nonlinear constraint with forecast uncertainties into a linear constraint that is easy to solve,and the differential evolutionbacktracking search algorithm is designed to solve the above optimization model efficiently.In the fifth chapter,a capacity optimization model for wind power/solar power/diesel generator/energy storage autonomous islanded microgrid energy storage system is constructed,which fully considers the multi-scale uncertainty coupling influence and autonomous indicator.Then,a flexible robust optimization method is also introduced to deal with forecast uncertainty variables in the optimal operation of energy storage systems.Furthermore,a multi-objective differential evolution-backtracking search algorithm is designed to efficiently solve the optimization model.The sixth chapter constructs a capacity optimization model for smart microgrid with wind/solar/storage that takes into account the demand response,which is used to research the economic impacts of demand-side response on capacity configuration and optimal operation for microgrid with wind/solar/storage.A day-ahead electricity prices decision making method based on the marginal cost principle is introduced to guide the operators to obtain the optimal capacity configuration and demand response scheme for microgrid with wind/solar/storage.This paper is supported by National Natural Science Foundation of China(51577073)and Natural Science Foundation of Guangdong Province(2017A030313288).Part of achievement of this paper has been applied in the engineering of Southern China Power Grid,which has gained a satisfactory profit for technology and economy. |
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