Research On Models And Algorithms Of Sectionalizing Switch Placement Of A Medium Voltage Overhead Line

The sectionalizing switch placement is a significant way to effectively improve thereliability of a distribution network. By optimizing the sectionalizing switch placement,the electrical power loss can be reduced, the reliability of the distribution network canbe improved, and also the economic benefit can be obtained.Assuming a uniform load distribution along a line of no detailed grid structure andload distribution，the model and algorithm of "minimum number of segments" havebeen proposed to meet the requirement of ASAI index for one feeder and a feedersystem of a medium voltage overhead line; also, the concept and algorithm of"maximum number of effective segments" have been presented to improve ASAI indexof overhead lines. First, a simplified ASAI estimation model of a single feeder (aerial orcable) and a feeder system is obtained. Through calculation and analysis, the minimumnumber of segments and maximum number of effective segments are recommended fordifferent load densities or feeder lengths. Studies show that for the line length of1~20km, the maximum number of effective segments for a radial line is from3to5,which is overall much lower than the those of5~15for a line with a tie; For a system ofmultiple feeders, the minimum number of segments for a line is related not only with itslength, but also with the number of its users and the other lines’ lengths and numbers ofusers; The segment number of3or less than7, which is recommended by existingrelevant guidelines, to some extent limits the further improving of distribution networkreliability.A new heuristic algorithm is proposed for the sectionalizing switch placement of amedium voltage overhead line of detailed grid structure and load distribution. Theobjective function includes the reliability indexes of System Average InterruptionDuration (SAIDI) and Energy Not Supply (ENS). The constraints involve the maximumallowable investment，user reliability requirement and maximum effective segments, etc.Based on the criterion of maximum product of “benefitted load” and “isolated linelength”, the concept and approach to determine the optimized candidate locations ofsectionalizing switches are presented for the feeders without/with a tie. Based on theoptimized candidate locations，a two-phase optimization algorithm is proposed forsectionalizing switch placement of a Medium Voltage overhead line of non-uniform distributed loads. The numerical examples not only show the effectiveness andpracticability of the proposed model and algorithm, but also show that the proposedsimple approach to optimize candidate locations of sectionalizing switches can providea reasonable and minimum number of switch candidate locations or can be used tocheck the results of other sectionalizing switch placement algorithms, and to helpestablish related guidelines to some a degree..