Geometrical Indices Of Distribution Network Security Region And Application In Enhancement Planning

Distribution System Security Region(DSSR)describes the maximum allowable operation region of the distribution network.DSSR is essentially a high-dimensional hypergeometry surrounded by hyperplane and coordinate axis in the state space.This thesis mainly studies DSSR geometrically and applies the results to enhancement planning.Firstly,the concept of DSSR surface area and algorithm based on dimensionality reduction sampling are proposed.DSSR surface area is defined as the overall size of the security boundaries of the distribution network.This thesis comprehensively studies the geometrical indices of DSSR.The surface area and volume of DSSR are closely related,therefore,the volume to surface area ratio(VSR)is defined as the reciprocal of the surface area required to form a unit volume.Taking the VSR of the sphere in the high-dimensional space as the benchmark,the concept of roundness is proposed,that is,the degree that the DSSR is close to the circle in geometry.VSR and roundness are applied to describe the overall shape characteristics of DSSR.The physical meannings of the above geometrical indices of DSSR are analyzed.Volume represents function.Surface area represents resource.VSR represents the resource required to realize unit function.The larger the VSR is,the smaller the resource required to realize unit function is,and the larger the roundness is,which means that the security region is closer to the circle and the shape efficiency is higher.The geometrical indices of DSSR of typical wiring modes are calculated and compared with the indices of geometric figures.Some interesting phenomena and conclusions are found.Secondly,geometrical incides of DSSR are applied to enhancement planning and an enhancement planning method of distribution network based on geometrical observation of DSSR is proposed.The results of geometrical observation conclude geometrical shape figures and indices.The distribution network can be evaluated from the shape and size of DSSR,which can comprehensively reflect the security and efficiency of a given distribution network.Total supply capability curve is also introduced into the enhancement planning method as a supplement.Finally,distribution network cases are given to verify the effectiveness of the geometrical indices and enhancement planning method.The results show that the geometrical indices proposed in this thesis can distinguish the distribution networks with different wiring modes in geometry.The enhancement planning method can intuitively show the changes of enhancement scheme in DSSR and TSC.The proposed method provides a new observation means and analysis tool for distribution network from the perspective of security and efficiency,which is an important supplement to the enhancement planning of the existing distribution network.