Power Flow Calculation And Analysis By Newton Method In Cartesian Coordinates

Power flow calculation is the foundation and core of power grid.The accuracy of power flow calculation has an important impact on the safe operation,rational planning and economic optimization of power grid.The essence of power flow calculation is mathematic problem.It is a problem to solve the non-linear algebraic equation.It must be solved by numerical iteration.Therefore,the convergence of power flow calculation is very important.Therefore,the study of power flow convergence is very valuable.And nowadays,the power grid is becoming more and more complex and the ill-conditioned network is increasing,which makes it impossible to obtain the required solution by using conventional methods.At this time,there are higher requirements for the power flow solution method of power grid.Researchers also put forward many methods.These methods have different advantages and different application environments.Newton method is the most commonly used and most practical power flow calculation method.From various perspectives,it is more valuable to improve the conventional Newton method on the basis of the ill-conditioned problem of power grid.The reason of ill-conditioned network non-convergence is usually the improper selection of initial value or the defect of Jacobian matrix itself.In this paper,the power flow non-convergence caused by Jacobian matrix is studied.In an ill-conditioned power grid,the power flow analysis is carried out by using the Cartesian coordinate Newton method.Combining with the results of the analysis and aiming at the theoretical reasons for its non-convergence,some improvements are made on the basis of the Cartesian coordinate Newton method,which improves the power flow convergence of the Cartesian coordinate Newton method by modifying theJacobian matrix elements of the Cartesian coordinate Newton method.At the same time,on the basis of the improved Cartesian coordinate Newton method,combined with Cartesian coordinate Newton method,and analyzed the feasibility of the two methods,combining the two methods reasonably to form another method to solve power flow.The simulation results show that the ill-conditioned network can not be converged by Cartesian coordinate Newton method,and the improved algorithm can make the ill-conditioned network converge.The combination of Cartesian coordinate Newton method and its improved algorithm can make the ill-conditioned network converge,and has better convergence than the improved algorithm.