Reliability Evaluation Of Distribution System With Microgrids

Distribution system connects the consumer directly, and its supply reliability canmake a great influence on consumer. There is a growing concern indistribution-system-reliability assessment due to the improvement of customerrequirement. With the development of distributed generation and related technology,in order to make better use of distributed generations, people views distributedgenerations and associated loads as a subsystem or a “microgrid”. Based on thedistribution system, the concept of microgrid is introduced. Microgrids’ friendliness,independence and flexibility are used to improve the reliability of distribution system.Bring microgrids into the existing distribution system is the future trend of the powergrid. The reliability assessment of distribution system with a microgid is the maincontent of this paper.In this paper, the concept of microgrid, the characteristics of distributedgenerations in the microgrid and the typical structure of the distribution system with amicrogrid is given.Further more, the operation modes, the control strategies and theprotection characteristics of microgrid are analyzed. The basic principles and thebasic methods of reliability assessment are analyzed in detail. The reliability indicesof distribution system with microgrids are included in this paper.Based on the current research, after in-depth study of the characteristic and theoperation mode of microgrid, this paper uses the analytical method for the reliabilityevaluation of distribution system with microgrids. New applicable feeder partitionmethod is proposed for the reliability evaluation of distribution system withmicrogrids. Considering the uncertainty output of intermittent DG and load, after thefailure of distribution system happens, in order to reduce the outage cost as much aspossible and to achieve the internal power balance of microgrid, dynamicly considersthe construction and reconstruction of microgrid, an algorithm based on the evolutionof subset-tree is proposed by simulating the phylogenetic tree to solve theconstruction of microgrid. Combined the intermittent DG with the energy storagedevices in the microgrid, the microgrid wind-PV-ES hybrid power system isestablished. Based on the idea of fault enumeration, it is combined with theconstruction and reconstruction of microgrid to form the reliability evaluation modeland algorithm of new distribution system with microgrids. The impact of theuncertainty of the output power of DG and load, the variation of system structure, the construction and reconstruction of microgrid after the failure to the reliability indexare considered. Example shows the scientificity and validity of the proposed modeland algorithm.