Study On Flexible Structure Of Smart Distribution Grid When Mass Distributed Generations Are Connected

Nowadays, a large number of distributed generations (DGs) have been accessed todistribution network. The operation mode of traditional distribution network, without ownsource and radial operation mode, has been changed into that of smart distribution network,with own source and mesh operation mode. DGs typically access into low or mediumvoltage distribution grid network. So it mainly affects the distribution grid network.The traditional distribution grid network’s function is only to distribute electricity.Comparatively speaking, the smart distribution grid is served as power interactive media.It owns power source internally to centralize power, transmit power, and allocate poweragain. So the smart distribution grid is called active distribution network or power deliverysystem.In this paper, distribution network structure change and DGs’ access restrictions arestudied, including:(1) Combined with the selected voltage level coordination principle to generalizeeach country or nation’s voltage level configurations. In response to the growing capacityof DGs, a higher distributed voltage level is proposed and the500kV voltage sequence(500/220/66/20KV) is recommended.(2) Generalize each country or nation’s distribution network structure. And decidefeasible location and capacity for DGs under the traditional distributed network thoughvoltage constraints(3) DGs are accessed to distribution network by micro-grid technology. Compare thepower reliability before DGs accessing to the distribution network and after DGsaccessing to the distribution network, and calculate minimum power limit of DGs’ access.Three common wiring situation of distribution network are analyzed. They are singleradiation wiring connected method, different bus loop wiring connected method and “N-1” standby wiring.(4) The future distribution network is closed-loop operation. An algorithm whichcombines small-world theory with multi-objective GA is proposed to decide the site andsize for DGs in meshed distribution network. The generating capacity of New England39-bus system is set to0. The load data is unchanged. The amended New England39-bussystem is used to verify the method right.At the end, summarize the text. Point out the problems and further research needed tobe resolved.