Calculation Of Theoretical Line Loss And Research On Factors Of Influencing It For Rural Low-voltage Distribution Network

The distribution line loss rate is an important technical economic indicator of electric power enterprises, it could reflect the level of the plan, design, operation and management of a power grid. As a major part of the supply network, rural low-voltage distribution networks have many characteristics such as the complex structure and poor equipments of the networks, and the widespread scope of power supply and a large number of electricity users, etc.,so its line loss occupys a relatively large proportion of the whole line losses in power network. Moreover, it is hard to be reduced. At the same time, because of the above characteristics of rural low-voltage distribution networks, an accurate calculation of theoretical line loss is restrainted by many factors which are of lack of complete line structure parameters and operatioin data, etc. Therefore, it is greatly necessary to be studied that the theoretical line loss of the rural networks is calculated accurately.The article is based on the subject of "study and evaluation of the theoretical line loss in a low voltage distribution grid" presented by Linxiang bureau of electric power, Hunan province. During moe than a year, we drew the supply networks of8power transformers and measure their line parameters, and collected the operating data at24hours for10times. Based on this evidence, some analysis has been done depthly and comprehensively that includes the characteristics, operating data of rural low-voltage distribution network, and the calculation methods of line loss and optimization and selection of various calculation parameters,etc..As a result, an improved load shape coefficient is presented in the paper which grealty increases the speed and accuracy of calculation of the line loss,it is not necessary to select a number of representative days to collect operating data. Moreover by it the line loss in a long time can be forecasted. At the same time the influence of the unbalanced three-phases load on line loss is analyzed, and an improved algorithm for considering it is presented and its validity is proved by the test. Finally, some measures for reducing the line loss are proposed, and some of them is also verfied to be effective by an example.