Study Of Power Flow Analysis And Transient Simulation For Tianjin Utility

Deep research on power flow problem and transient stability simulation forTianjin power grid is essential for the security and stability of Tianjin or even NorthChina power grid. Power flow calculation is one of the most widely used, the mostbasic and most important electrical calculation. Transient stability simulation is themost commonly used method of power system stability analysis. However, bothpower flow and simulation calculation are time-consuming for large scale powersystems. Most of the time is spent on solving the nonlinear equations and the modifiedequations. Fast algorithm for solving equations and strategy for acceleratingsimulation can speed up the process of power flow calculation and transient stabilitysimulation.In this thesis, new power flow algorithm and new method for power systemtransient simulation are proposed to analyze Tianjin power grid. The main contentsincluding two parts are presented as follows:Firstly, a power flow algorithm based on the tensor method is proposed. Thetensor method is used to solve the nonlinear equations of the power flow calculation.The tensor method is particularly effective for solving nonlinear algebraic equations. Aquadratic model with a second-order term is applied during each iteration process oftensor method, which has better convergence compared to the traditional Newtonmethod, especially when the Jacobian matrix is ill-conditioned or even singular. Thesimulation results show that the power flow algorithm based on tensor method hasbetter convergence, and can be used to solve heavy-load power flow problems.Excellent simulation results on both Tianjin and North China power grid show thevalidity of this algorithm.Secondly, based on SGMRES (m) algorithm a new transient stability simulationmethod is proposed. This method uses SGMRES(m) (Simpler GMRES(m)) algorithmto solve the linear equations of the transient simulation calculation. SGMRES(m)improves the generation process of the standard orthogonal basis of GMRES (m). Soat the end of each iteration process, solving of the least squares problem is avoided,and only the linear equations whose coefficient matrix is upper triangular matrix needsto be solved. Thus, with a perfect convergence, computational burden of thecalculation of linear equations is effectively reduced. At the meantime, in order to accelerate the simulation speed, this method is integrated with accelerating techniqueincluding dishonest Newton strategies and the coefficient matrix preconditioningtechnique. Multiple numerical examples show that this method can speed up theprocess of simulation effectively. This transient stability simulations algorithm isapplied on both Tianjin and North China power grid, and the critical clearing time andmaximum output of key generators in the case of representative fault are obtained.