Principles Of Security Region For Smart Distribution Systems

Distribution system is the infrastructure of a city and will play an important role in the future Smart Grid.This paper studies the principle of distribution system security region(DSSR).DSSR is the set of all the secure operating point in the state space.DSSR determines both the security boundary of the system operation and power supply capability.The research on DSSR is of great significance for smart distribution system.First,DSSR can determine the operational boundary and total supply capability(TSC).Second,DSSR provides a new observation view of distribution systems.Third,DSSR can develop the new advanced operating,monitoring and planning technology.The work in this paper is the foundation of DSSR.The contributions are from 2 aspects.On one hand,aiming at the informational and automated distribution networks without distributed generators(DGs),the definition,existence,geometric characteristics,mechanism and application approaches are studied.The main contributions are as follows.1.The existing concepts of DSSR are organized and standardized..The mathematical definition system is developed.2.The existence of DSSR is proved.First,the observation method of DSSR is proposed,by which the DSSR boundaries of many case grids are observed.Then,the existence of DSSR is mathematicaly proved.Finally,the existence of DSSR is certificated in an actual urban distribution network.3.Through the observation,the geometric characteristics are concluded,including the inner density of DSSR and the approximately linear of the DSSR boundary.These characteristics are then mathematically proved.4.The weighted balance degree is proposed to describe the topology of feeder links.The mechanism of network topogoly(feeder links)on TSC is analyzed.5.The distribution network reconfiguration based on DSSR is proposed,which can better balance the security and efficiency of a system compared with the traditional reconfiguration method.The planning method of feeder links based on TSC is proposed,which can better develop the TSC.On the other hand,the DSSR is expanded to the active distribution networks with DG integration.The main contributions are as follows.1.The existence of the security region of active distribution network is mathematically proved.2.The total quadrants security region(TQSR)is modeled,which is not only suitable for the active distribution networks with DG integration,but also lays a bisis for the complete security region considering energy stirage,micro-grids and demand response of smart distribution networks.3.The map set of DSSR 2-D shapes is proposed.The features of shape,quadrant and security feature are concluded for different DG penetrations..