Microgrid Cluster Network Reconfiguration Considering Probabilistic Survival Time

With the large-scale distributed power supply connected to the distribution network,it not only relieves the energy pressure,but also brings opportunities and challenges for the operation of the distribution network.When a large area of fault in the distribution network breaks away from the main network,DG can be used to form a small power system island to restore power supply for the lost load.However,the fluctuation of DG power will affect the operation reliability of distribution network.In addition,in the current research on distribution network fault recovery,island running time is usually ignored or approximately processed,which may misevaluate the actual island running time,thus leading to unreasonable planning.Finally,the traditional island division method does not consider the actual operation time demand of the island,once the power imbalance will abandon Wind Turbines,Photovoltaic or load reduction,which will affect the stability and reliability of the island operation.So to solve above problems,this thesis mainly studies include cellular network of distribution network fault island after the operation,first of all to consider uncertainty factors to the operation of the power distribution network,optimization,and then put forward considering the uncertain factors in the island’s largest probability of survival time evaluation methods,and puts forward the thinking of micro survival probability of isolated net net group division method,etc.The main research contents are as follows:Firstly,in order to accurately describe the randomness and volatility characteristics of Wind Turbin and Photovoltaic output,a scene generation method based on stratified sampling method and scene reduction theory was adopted in this paper.That is,the initial sample matrix is generated based on the Latin hypercube sampling method,and then the sample matrix is reordered considering the correlation of random variables.Finally,the initial sample set is reduced to the required number of scenes based on the synchronous back-generation elimination reduction method,and the final sourk-charge output scene and the occurrence probability of the scene are obtained.The simulation results show that the method can effectively simulate the diurnal variation of source-charge power,and the method is used in the subsequent operation evaluation of the island system.Second,several random failure occurred when the power line of the extreme situation,in view of the traditional method of error estimate long island runtime problems,put forward an active distribution network optimization under the island’s largest probability of survival time of assessment methods,failure occurs when any of several distribution network line,by optimizing the MT and the output of the energy storage device,The maximum probability survival time of the current random island is obtained,and the effects of MT capacity and energy storage device on probability survival time of the island are quantified.Finally,to solve the problem that the traditional island division method does not consider the requirement of the actual operation time of the island,an isolated network division method considering the probabilistic life time of the micro-network group is proposed.Taking the maximum weighted power supply duration as the objective function,the outer layer is divided into islands considering the constraints of line structure.The inner layer considers the security constraints of power grid operation,and adopts particle swarm optimization algorithm to obtain the optimal partition results.Finally,through the comparative analysis of static island division,dynamic multi-period division and multiple line faults,it is proved that the division method of the group isolated network considering the probability of island operation can achieve the optimal power supply recovery situation.