A Method For Calculating Distribution Network Line Loss With Distributed Generation

Line loss,the abbreviation of power loss in power grid,is the loss of power generating at some situations including transmission,substation,distribution and marketing in the process of power transmission from power plant to power user.For many power supply enterprises,line loss rate is an important comprehensive economic index to evaluate the performance of their enterprises.Distribution network line loss accounts for a large part of the total power network loss,so with the transformation of urban and rural distribution network and the gradual development of power market,the theoretical calculation of line loss on distribution network becomes increasingly significant.With the continuous development of society,the demand for power supply poses an extreme challenge to the distribution network while the application of distributed generation in distribution network is becoming more and more widespread.The existing theoretical line loss calculation methods usually regard distributed generation nodes as negative loads,ignoring the known parameters and operation status of distributed generation,and meanwhile injection power of new energy is usually instable and noncontinuous,which bring the accuracy problem of line loss calculation.Therefore,it is of great theoretical and practical significance to study the theoretical line loss calculation method of distribution network with distributed generation.In this thesis,the traditional theoretical line loss calculation method and the advantages and disadvantages of the average current method are analyzed in detail.Secondly,it briefly introduces the causes of line loss and the impact of distributed generation on line loss calculation after connecting to distribution network.Thirdly,several common distributed generation models were introduced,including working principles and grid-connected operation modes,and analyses on current calculation methods of line loss in distribution network with distributed generation.In addition,the calculation model of line loss based on loop analysis methods is deduced and analyzed.Finally,with considering the known operating parameters of distributed generation,an improved theoretical line loss calculation method of distribution network with distributed generation is proposed based on the average current method.This algorithm weakens the assumption of average current method,and takes fully into account the known parameters of distributed generation,which improving the accuracy of line loss calculation to a certain extent.In the process of correcting calculation,the path mutual resistance matrix is directly formed by searching.The matrix calculation of high dimension is avoided.The method is easy to implement.Taking a distribution line in Shandong Province as an example,the power flow calculation results are taken as true values,and the results of the average current method and the proposed algorithm are compared and analyzed in various scenarios,which verifies the effectiveness of the proposed algorithm.