Optimization Of Day-ahead Scheduling For Independent Community Microgrid

The electrical power generation via traditional resources are becoming more and more unsuitable to fulfill the requirement of environment protection and sustainable development.Microgrid,means integrated small scale power network with small and distributed generators and flexible load as well as energy storage,usually with stabilities of autonomous control,protection and management,has been one of the most important development direction of electric power industry.However,the study object in this thesis is different from traditional microgrid.In fact,the prototype of the study object is from the real power systems in rural Pakistani regions,with unique characteristics such as larger scale than traditional microgrid,non-negligible topology of the network,usually with island operation mode from public transmission networks,hence it is called independent community microgrid(ICMG).The scale of ICMG is between normal distribution network and traditional microgrid,so it is more susceptible with disturbance than distribution network.What’s more,its network topology structure and power flow should not be neglected.Also,since the network always running under a low operation voltage level and being unbalance in three-phase load flow and voltage,the operation statement is strongly influenced by external random disturbance.Since there is almost no precedent for the research on this kind of microgrid at present,reasonable operation scheduling method should be developed to deal with those characteristics,otherwise it is impossible to be operated flexibly,economically and environment-friendly.In this thesis,day-ahead scheduling model for traditional microgrid is used for reference to propose the corresponding model for ICMG,in which the optimization objectives include operating cost,load satisfaction as well as the valley-to-peak level and smoothness of the load curve.On the other hand,the optimization objectives and constraints are rewritten for ICMG three-phase asymmetric power flow.The optimization objectives are realized by coordinating both the controllable and uncontrollable generators,energy storage and the ability of demand side response of loads.Furthermore,to considering of the characteristics of ICMG,the minimized power losses of the network is extended into the optimization objective set,while constraints from both the power flow equation and power balance equation are also incorporated.The most difficult part of the optimization model is from the stochastic effect from renewable sources,which should be specially considered in the model.The price processing method of two-stage market mechanism is innovatively adopted in the optimization model,and special consideration is given.Concrete works are carried out based on the ideas mentioned above.Firstly,the ICMG model is established,and concrete optimization problems related with the day-ahead scheduling of ICMG are explicitly formed.The objective of maximized expected profit is proposed to deal with the stochastic of renewable energies,and the suitable renewable output conditions for day-ahead scheduling is acquired via scenario reduction by Latin hypercube sampling.Multiple objectives are considered and detailed three-phase power flow model is incorporated to propose the final dynamic planning model for day-ahead scheduling,which can be solved by classical optimization algorithms.The model is applied in a real Pakistani sample,which is validated by reasonable optimization results.