畢業(yè)設(shè)計(jì)電氣工程及其自動(dòng)化專業(yè)外文翻譯-文庫(kù)吧資料
2024-12-09 17:55本頁(yè)面
【正文】 , the modulus of the entries on the main diagonal of the admittance matrix could indicate the magnitude of the determinant of the submatrices on the main diagonal of the Jacobian matrix. For convenience, we make use of admittance matrix to determine the order of numbers. Scheme II a) Form the nodal admittance matrix。 nodes 24 are load nodes. Following the original node number, the DC power flow equation is: To simulate puter numerical calculation operations, four significant figures will be used to solve the problem. Executing GEM without pivoting on (1) yields the solution[ θ2,θ3,θ4]T=[,]T, whose ponents differ from that of the exact solution [θ2, θ3,θ4]T=[,]T. A more exact solution could be obtained by plete pivoting: [θ2,θ3, θ4]T=[,]T, and the order of the node after row and column interchanges is 3,2,4. So this is a more reasonable ordering scheme for the purpose of getting more high accuracy. 外文翻譯 （原 文） 6 IV. THE INFLUENCE OF NODE REODERING ON THE PERFORMANCE OF NEWTONRAPHSON POWER FLOW METHOD Sample 6node work On the basis of the abovementioned analysis, the scheme for node reordering will not only affect memory requirement but also the accuracy of the solution in solving linear simultaneous equations. So performance of NewtonRaphson power flow method will be different with various node ordering. In this section three schemes of ordering for different purpose will be applied to a sample 6node work shown in Fig 2 to pare the influence of them on the accuracy of the solution, the convergence rate, the calculated amount and the memory needed in power flow putation. The detail of the performance is shown in table IV. A. Puropse 1 Saving Memory as far as possible At present, there are various schemes widely used for node numbering in nearoptimal order to reduce fillins and save memory. The only information needed by the schemes is a table describing the nodebranch connection pattern of the works. An order that would be optimal for the reduction of the admittance matrix of the work is also optimal for the table of factors related Jacobian matrix. Different schemes reach different promise between programming plexity and optimality. In this paper, what we concern about is how the result of the numbering 外文翻譯 （原 文） 7 affects the putational performance. The programming efficiency is beyond the scope of the present work. To save memory, a dynamic node ordering scheme similar to the third scheme presented in [2] is adopted in this section. Execution steps of the algorithm are as follows. Scheme I a) Number the node degree of which is one. If more than one node meet this criterion, number the node with the smallest original number. If there are not su nodes any more, start with step b)。 NewtonRaphson method 。 sparsity。外文翻譯 （原 文） 1A Comparison of Power Flow by Different Ordering Schemes Wenbo Li, Xueshan Han, Bo Zhang The School of Electric Engineering Shandong University Jinan, China Email: Abstract—Node ordering algorithms, aiming at keeping sparsity as far as possible, are widely used today. In such algorithms, their influence on the accuracy of the solution is neglected because it won’t make significant difference in normal systems. While, along with the development of modern power systems, the problem will bee more illconditioned and it is necessary to take the accuracy into count during node ordering. In this paper we intend to lay groundwork for the more rationality ordering algorithm which could make reasonable promising between memory and accuracy. Three schemes of node ordering for different purpose are proposed to pare the performance of the power flow calculation and an example of simple sixnode work is discussed detailed. Keywords—power flow calculation。 node ordering。 accuracy。 linear equations I. INTRODUCTION Power flow is the most basic and important concept in power system analysis and power flow calculation is the basis of power system planning, operation, scheduling and control [1].Mathematically speaking, power flow problem is to find a numerical solution of nonlinear equations. Newton method is the mos
公司管理相關(guān)推薦
鄂ICP備17016276號(hào)-1