Reliability Assessment Of Distribution System With Micro-Grids

Micro-grid is a very promising solution to the problem of distributedgeneration integration, while enable distributed generation performs to itsfullest potential. As a complementary for traditional power system,micro-grid provides a new direction for the development of modern powersystem.Before the integration of micro-grid, traditional distribution network iswell known for its character of “ring network design, open loopoperation”. However, when equipped with micro-grid, distributionnetwork become a complex system with multi-power-sources andmulti-customers. And when it comes to large scale contingencies,micro-grid could run in island mode to continue its power supply service. Asa result, the reliability theories and evaluation methods for distributionnetwork with micro-grid would embrace a series of changes. Currently,most studies concerning the reliability micro-grid are generally focused ontreating each DG as an independent generator, and ignore the temporalproperties of DG output, which would inevitably lead to an inaccurateconclusion concerning the potential impact brought by micro-grid.This thesis analyzes impacts brought by micro-grid to the entire powersystem as a whole, through a thorough research on the definition, structure,control and operation of micro-grid. Minimal path method is adopted as thevery algorithm to evaluate the reliability of micro-grid, which is based ontraditional distribution network reliability assessment theories. In order tosimulate the practical system more accurately, this thesis considers thesequential output characteristic and sequential load characteristic of DG.Traditionally, the reliability indexes fail to depict the whole picture of the impacts brought by micro-grid, and to curb this weakness, this thesisproposes two novel reliability indexes for the study of micro-grid.Given the reliability models, this thesis makes a comparison ofdistribution network reliability with micro-grid based on different DGconfigurations by implementing the proposed new micro-grid indexes. Thetest results suggest the following: A joint operation of PV and wind powercould improve the system reliability significantly; the integration ofmicro-grid serves to improve the overall reliability of the entire distributionsystem; the location, scale and configuration of micro-grid plays animportant role in the reliability of the distribution system; And theintegration of micro-grid to the distribution system could lead to betteroverall benefit.