Optimal Scheduling And Static Security Analysis Of Active Distribution Network

Aggravation of environmental pollution and energy crisis makes the rapid development of green renewable energy distributed generation technology.Adapting to the large-scale integration of distributed generation(DG),improving the compatibility with DG and consumptive ability of green energy,promoting the optimal operation of distribution network are the core value of active distribution network(ADN).The optimal scheduling and operating of ADN need to co-ordinate various controllable resources.In the scheduling work,the benign interaction of sources,network and loads should be realized,and the uncertain factors are supposed to be properly handled.The static security analysis of ADN should grasp the time sequence characteristics of network operation,as well as consider the islanding operation and active management of ADN,which is helpful to enhancement of system security.In this paper,the optimal scheduling and static security analysis of ADN are deeply studied,the main achievements are as follows:(1)An economic scheduling method for ADN considering the coordination of resources,network and loads is proposed.Based on the coordinated interaction of sources,network and loads,the control means of scheduling include DG,energy storage system,flexible network topology,flexible loads shedding and shifting.Considering purchase cost,loss cost and demand side management cost,day-ahead economic scheduling model for ADN aiming at minimizing operation cost is established.The model is solved by improved harmony search algorithm.Finally,the correctness and validity of the scheduling method are verified by an example.(2)Based on the research of economic scheduling,a novel day-ahead optimal scheduling and operating method for ADN considering violation risk is presented.In day-ahead stage,operation violation risk resulted from uncertainty of load,wind and solar resources is considered.Scheduling scheme's economy and security are both taken into account,and a multi-objective day-ahead optimal scheduling model aiming at the minimum of operation cost and violation risk is established.The scheduling means of ADN include DG,energy storage system,reactive power and voltage equipment,flexible network topology.Ideal point method is used to deal with the multi-objective model.The optimization problem is solved by improved harmony search algorithm,and the violation risk indexes are calculated based on probabilistic power flow method of cumulant.The proposed scheduling method is applied to solve the optimal scheduling and operating problem of ADN test case.The violation risk of the scheduling scheme is deeply dissected,and based on comparison and analysis,the rationality and superiority of the proposed scheduling method are verified.(3)A static security analysis method for ADN is proposed,which is based on time sequence characteristics and island operation of ADN.Considering DG,energy storage system and shiftable load,time sequence models of elements and security evaluation indexes applicable to static security analysis of ADN are established.Based on two aspects of time sequence,i.e.the fault occurrence period and network operational status during fault time,considering island operation and active management,a static security analysis method of N-1 branch fault in ADN is put forward.In the case,using the presented evaluation indexes and analysis method,the security of different periods,different branches and system is evaluated quantitatively,to realize the accurate positioning of weak period and weak branch of ADN.