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Research On Multi-objective Optimal Operation For Microgrid

Posted on:2018-12-28Degree:MasterType:Thesis
Country:ChinaCandidate:Y T ChuFull Text:PDF
GTID:2322330518466891Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
At present,As the increased supply imbalance of fossil energy,the continued deterioration of environment,the increased demand of load and the improved requirements for power quality,high energy utilization rate and materials flexibility of distributed generation(DG)have got attention.Although the large-scale use of DGs have brought a lot of benefits,the power of intermittent,randomness,volatility and other shortcomings lead to the problem of grid connection.Microgrid(MG)can collect a variety of types of DGs to ensure DG play advantages,can supply electricity,heat and other different forms of energy,can switch the condition of grid connected and isolated neatly,can be used to solve the problem of grid connection.The optimal operation of MG is in accordance with the DG level limit and MG system level constraints,reasonable adjustment of each unit power output,reduce the cost of power generation,improve energy efficiency and reduce pollution et al.Therefore,it is great practical value to study the optimal operation of MG with a variety of DGs.On the basis of consulting and summarizing the domestic and foreign literature,this thesis summarizes the research background and development of MG and its optimal operation.The basic concept of MG system and its operating characteristics are introduced.The network and operating mode of a typical structure of MG is studied.It is the theoretical basis for the following MG optimal operation under different conditions.Focusing on the optimal operation of grid connected MG,this thesis illustrates in an intuitively heuristic way the optimal operation scheduling strategy for MG under the guidance of the spot power price(SPP)theory.According to the time-of-use price mechanism,this strategy divides the whole day into three periods: the peak,the flat and the valley.The operational control strategy is established respectively in different periods based on the comparison with the SPP of main grid and the SPP of micro-sources considering the impact of state of charge(SOC)of storage battery(SB).Then the ladder-like penalty coefficients of SB are designed and included in the objective function of optimal operation model to guide the scheduling sequence of the MG.Finally,the output of controllable micro-sources,the charge and discharge of SB,and the power interchange between MG and the main grid are optimized by pareto optimal path fast non-dominated sorting genetic algorithm(POP NSGA-?).According to the steps above,the role of peak load shifting of SB can be realized and the operation economy of MG can be improved.The validity of the proposed strategy and model is verified by the daily scheduling of a combined cooling heating and power(CCHP)MG system.For the optimal operation problem of isolated MG,a multi-objective operation optimization method of MG with SB is proposed.The method consists of two parts: the management of operation mode of energy storage unit;the optimization o f controllable DG.The control strategy of power difference is used to manage the SB by taking the load demand,power generation expect of renewable resources,and SOC of SB.For the sake of decrease economic and environmental cost,taking power balance,limit value and ramping constraint of controllable DG into account,the output of controllable DG is distributed by using improved algorithm.This method can not only play a role to peak load shifting of SB,but also realize the economical and environmental operation of isolated MG.A typical daily optimal operation is used as an example,which verifies that the method is feasible and effective.
Keywords/Search Tags:Microgrid, Grid connected operation, Isolated operation, Spot power price, Optimal operation
PDF Full Text Request
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