Research On The Planning Methods Of 10kv Medium Voltage Distribution Network Grid

Distribution network is an important part of power system,distribution network grid plays an essential role in power transmission,scientific and reasonable distribution network grid planning can not only improve the economy and reliability of power system operation,meet the increasing load demand of users,guarantee the power supply quality,but also can save a lot of investment,operation and maintenance costs for distribution network operators.Distribution network grid planning is the core of distribution network planning,which includes the new construction of grid in the area to be planned and the expansion and transformation of the existing grid in the completed area.Thus,on the basis of absorbing the excellent theories and experiences of distribution network grid planning at home and abroad,grid planning methods are proposed,which are suitable for the above two kinds of scenarios respectively,this paper mainly does the following work:Aiming at the problem that the number of load nodes is large in large-scale distribution network,it will add decision variables of the distribution network planning model and increase planning difficulties when considering all load nodes at a time,so this paper puts forward a grid planning method based on load nodes clustering blocks,for the new construction of grid in the area to be planned.Firstly,load weight is proposed to improve classic k-means clustering algorithm and then load nodes are clustered by the improved k-means algorithm.Secondly,a connection matrix which can represent the upstream and downstream relations of load nodes is established,to speed up current calculation and analysis process about the influence of tie lines location on the downstream load transfer of a fault line.Then,the improved minimum spanning tree algorithm is used to solve the main network planning model,which minimizes annual investment cost and operation cost while taking geographical factors into consideration.Finally,in order to further improve the reliability of network planning scheme,tie lines between load nodes clustering blocks are set up,aiming at minimum annual investment cost and outage cost,meanwhile,according to different load transfer conditions,different methods to calculate the outage cost are adopted.Aiming at the problem that the rural distribution network reconstruction project generally does not take into account the difference of risk bearing capacity among different township regional distribution networks and the large fluctuation of township regional load,the chance constrained programming theory is introduced,and a line upgrading method which takes into account the uncertainty of load and takes into account the difference of risk bearing capacity of different regional distribution networks is presented,for the expansion and transformation of theexisting grid in the completed area.Firstly,the method of nonparametric kernel density estimation is used to express the uncertainty of load.Then,taking into account the difference of risk bearing capacity of different township regional distribution networks,the evaluation index system of risk bearing capacity is established,and the combined weighting method is used to evaluated the risk bearing capacity of different township regional distribution networks.Finally,the chance constrained programming model of lines upgrading is established,and according to the risk bearing capacity assessment results of different township regional distribution networks,different confidence levels are selected to determine the upgrading plan of the distribution lines,thus,to a certain extent,the lean investment of rural power grid transformation can be realized and the adaptability of lines upgrading scheme to the uncertainty of load can be enhanced.In this paper,the method of distribution network grid planning based on load clustering blocks is proposed to optimize the new 10 kV network structure in a planned area in Meihekou City of Jilin Province.At the same time,the line upgrading method considering the difference of risk bearing capacity of different regional distribution networks proposed in this paper is used to upgrade the 10 kV township regional distribution lines which are within the power supply range of a substation in a certain area of Jilin Province.The example results support the validity and effectiveness of the methods proposed in this article.