Study On Ultimate Line Loss Of Distribution Network Considering The Influence Of Distributed Generation Access

Line loss rate is an important comprehensive indicator to measure the economic and technical performance of power grid operation,and it is also one of the core indicators that power companies pay more attention to.In the context of advocating energy conservation and emission reduction,grid companies are also adopting corresponding measures to reduce losses and formulate relevant reduction indicators.However,it is difficult to carry out accurate theoretical line loss calculation in the distribution network at present.There is no theoretical basis for setting a reduction target.At the same time,a large number of distributed generations began to access the distribution network,which had a significant impact on the distribution of power flow in the distribution network.It increased difficulty in calculating theoretical line loss of distribution network and setting evaluation criteria.Based on the above background,this paper mainly considers the limit line loss of distribution network affected by distributed generation access,mainly to complete the following work:(1)Research status of limit line loss calculation,line loss management,loss reduction measures and random power flow calculation,provides a basis for establishing limit line loss calculation model and proposed loss reduction measures.(2)A method for calculating the limit line loss of distribution network after distributed power access based on Monte Carlo random simulation is proposed.By simulating distributed power output and random fluctuations in load.The shape factor is used to quantify the effect of this fluctuation on line loss.The influence of distributed power access on the limit line loss is analyzed,and the line loss calculation model is modified on this basis.A limit line loss calculation model for distributed power supply distribution network is established.(3)The calculation model of limit line loss of distribution network based on semi-invariant is proposed to solve the calculation of limit line loss after accessing distributed power supply in large-scale distribution network.The calculation method of semi-invariant is derived from the distribution network load and distributed power output model.The linearized flow equation is used to calculate the semi-invariant of the state variables and line losses of the distribution network.Solving the probability density function and cumulative distribution function of each state variable and limit line loss by Gram-Charlier series expansion(4)The problems existing in the calculation and management of current line loss are summarized.The common loss reduction measures are analyzed from the perspective of theoretical line loss and management line loss.Starting from the line transformation,the overall loss reduction effect is the objective function.Considering the economic constraints,the optimization model of the loss reduction measures is established and solved by dynamic programming.The above model is verified by taking a regional medium voltage distribution feeder and IEEE34 node system as an example.The limit line loss of the corresponding distribution network is calculated and the influence of distributed power access on the limit line loss is analyzed.This paper analyzes the method and the feasibility of the proposed model.