| The research of security region for transmission system has formed systemic theory and continues to depth in recent years.Meanwhile,as distribution automation became popular,distribution system turn much closer in the degree of automation which made the proposal of distribution system security region(DSSR)come true.From another perspective,the successful application of security region in distribution networks provides the possibility for its generalization in other networks except electric systems.In this paper,we generalize security region into common network with capacity-load model,put forward its definition,model and evaluation control method which can apply into assessment of N-1 security and load adjustment prior to failure.Finally it is the comparison with invulnerability.First,the paper introduces concept and model of DSSR model based on feeder connection which take transformer N-1 and feeder N-1 into consideration at the same time.The method is refined to feeder space.Second,the paper discover separation phenomenon under N-1 condition for common networks through amounts of simulation experiment.And we put forward general N-1 security,definition of security region and mathematical model.Third,this paper explains its application value from assessment of N-1 security,explanation of the relationship between load level and resistance ability to N-1 failure,and load control and adjustment ahead of time.We verify its value and correctness by applying it into abstract network,real network and different scale networks.Finally,we design comparison method to show difference between secure distance and invulnerability.It can be seen that secure distance index and invulnerability index are very consistent in judging the reliability of a system,meanwhile,the former can bring security region information to eliminate hidden dangers in advance and be appropriate for online security surveillance and control based on faster calculation speed. |
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