Electromechanical Transient Simulation Based On Iterative Methods For Power System

Transient stability simulation is the most commonly used method of power system transient stability analysis. It costs a lot of time for the transient stability simulation calculation, and most of the calculation time is spent on the solution of linear equation. Employing of the accelerating strategies and algorithms can speed up the transient stability simulation calculation. Long-distance power transmission, heavy load, and the large area interconnection are gradually becoming the main characteristics of the modern power system. Thus, ill-conditioned power flow problem will likely be a key issue for the power system analysis. So the study of ill-conditioned power flow algorithm and fast transient stability simulation strategy is very helpful for the operation, plan and design of power system.In this thesis, power system transient stability simulation and ill-condition algorithm are studied and the main contents are presented as follows:Firstly, based on inexact Newton-SGMRES (m) algorithm a new transient stability simulation method is proposed. This method uses SGMRES(m) (Simpler GMRES(m)) algorithm to solve the linear equations during the iteration from nth step to n+1th. SGMRES(m) improves the generation process of the standard orthogonal basis of GMRES (m) to avoid the calculation of the least squares problem, and change to solution of the linear equations whose coefficient matrix is upper triangular matrix.. Thus computational quantity is effectively reduced, and the good convergence of the algorithm is achieved. At the meantime, in order to further accelerate the simulation speed, this method is integrated with accelerating technique including dishonest Newton strategies and the coefficient matrix preconditioning technique. Multiple numerical examples show that this method can speed up the electromechanical transient simulation calculation significantly.Secondly, an ill-conditioned power flow algorithm based on the tensor method is proposed. This algorithm uses the tensor method to solve the nonlinear equations. The tensor method is particularly effective for solving of non-singular and singular nonlinear algebraic equations. A quadratic model with a second-order term of the nonlinear equation is solved during each iteration process of tensor method, which has better convergence compared to the traditional Newton method, especially in the condition of the Jacobian matrix owning large condition number or being singular. The simulation results show that the tensor method based power flow algorithm has better convergence, and can be used to solve ill-conditioned power flow problem.