Dimension Of Distribution System Security Region

The theory of Distribution System Security Region(DSSR)has been gradually improved.The scale of DSSR is a basic issue,but there are very few studies on it.Therefore,this paper studies the scale of DSSR systematically and proposes the concept and calculation method of unary dimension in the form of N×N.The main works are as follows.Firstly,the basic concept and model of DSSR are introduced.By analyzing DSSR binary dimension and then introducing the concept of the number of equivalent feeders,DSSR unary dimension in the form of N×N is proposed,which not only conforms to people’s habit of looking at space but also can get a single value to indicate DSSR scale.This method is conducive to comparing the scale of different DSSRs.Secondly,the calculation method of DSSR unary dimension based on feeder association matrix is given.The algorithm consists of three steps:(1)writing a feeder association matrix according to the network structure;(2)extracting feeder combinations;(3)calculating the number of equivalent feeders,and obtaining DSSR dimension.Thirdly,the effectiveness of proposed concept and algorithm of DSSR dimension is verified by a case,and the relationship between DSSR unary dimension and the network structure is analyzed.When the number of feeders is constant,DSSR unary dimension depends on feeder connection of the network structure.The more the feeders are connected,the larger the DSSR dimension is.When the connection structure is the strongest(i.e.full connection),the DSSR dimension gets the maximum value;When the connection structure subject to N-1 guidelines is the weakest,the DSSR dimension gets the minimum value;For ordinary network structure,the DSSR dimension takes middle value between them.Finally,unary dimension is applied to solve the problem of large combination scale for two-dimensional observation on DSSR.And a simplification method for DSSR observation based on unary dimension is proposed.By our method,the combinations that are unnecessary can be eliminated,which simplifies the result of DSSR and is helpful for DSSR theory to be practical.In addition,this paper also discusses the application of dimension in the simplification of state space.