A Method For Distribution Network Power Flow Calculation Based On Banded Symmetrical Matrix Equation

Because of the defects in power flow calculation of the radial distribution network ,this dissertation is based on tree structure, calculational method theory and the basic theory of circuit, provides an in-depth research on the approach of calculating power flow in the distribution network systematically.In recent years, the automation of distribution network is paid much attention. with the development of distribution management system, it has become hot spot. As important part of the DMS, distribution power flow calculation is the basis of the study and analysis of the automation of distribution network. Compared with transmission network, the features of distribution network are: its structure is closed loop and the equation of open loop, when the system runs safely, it is the radial structure. Only when it run with defect and take turn the loads, it is possible to appear transient circuit structure; Structure of network, R/X ratio of line parameter is large; PQ nodes are more, and PV nodes are few. Presently, It is prevalent that the flow in distribution network is calculated by the same method as used in transmission network power flow calculation, such as Newton-Raphson method, fast decoupled method, this unavoidably brings some problems and they are not effective. So many researchers bring forward some methods that are suit for distribution networks. Though they solved the problems of power flow calculation in different ways, such as current-influx method, circuit impendence , improved Newton-Raphson method, and tree structure calculation method, these method dispose distribution power flow calculation in different ways ,these method still exists some problems. of configuration.This dissertation is based on the characteristic of distribution structure, considering the voltage level, and proposing a new calculational method for tree structure and simplify the node numbering scheme, this method shape symmetrical banded node-inductance matrix, and apply back/forward sweep algorithm to distribution network power flow calculation, the algorithm turn the power flow equations from nonlinear equations to two groups of linear equations, and avoid the unstable equations ,and make the power flow equations immune to the ratio of R/X ,with characteristic of lower storage, faster converging speed and calculation speed.