Reserch On Optimal Order Reduction Of Power System State Space Equation

The interconnection of the lar ge area power system and the diversification and complication of the system controller lead to a sharp increas e in the num ber of dynamic equations.In "San Hua" power gr id,the dim ension of state m atrix in analysis of small disturbance stability has reached more than 20 thousand.The QR algorithm for solving the full dim ensional eigenvalue has the obvious advantage of the strong numerical stability,but the influence of the round off error may lead to the failure of the solution in the stability analysis of large-scale power system.This dissertation analyzes the algorithm structure and calculation process of the specific mode order reduction m ethod.This method classifies the state variables according to the eigenvalue sensitivity and reduce the order,then uses the improved Raleigh quotient inverse iteration m ethod to com pute the eigenvalues of the electromechanical model.The computational efficiency is low,because one reduced order model can only accurately calculate the eigenvalu es of one electrom echanical model.In the actual system,the characteristics of some electromechanical modes are similar or similar,and a reduced order model can be shared within the allowable error range.The main work of this dissertation has two parts: one is to group the electromechanical model;the other is to determine the optimal number of generators in each group.Improvement of the reduced order model.Choose the relevant factors of the generator for the power angle variable as the basis to group the electromechanical model,each group uses one reduced orde r model,so that the the am ount of calculation is greatly reduced.Optimization analysis of reduced order m odel.Determine the optim ization ideas of model order reduc tion according to the m odel reduction m ethod of the general control system.By com paring the accuracy of th e eigenvalue calculation when the number of generators in the model is different,determine the optimalnumber of generators in the model on the premise of ensuring the accuracy of calculation.Calculation and verificati on in 23 machine system and 70 m achine system.Group the electrom echanical model according to the relev ant factors,o ptimize the reduced order model according to the idea of model reduction method,then calculate the electromechanical mode eigen value of large scale po wer system.The m ethod avoids the failure of the QR full dim ensional eigenvalue method when the dimension of the state matrix is huge,and one reduced order model can be used to calculate the eigenvalues of a plurality of electromechanical modes,which can further improve the computational efficiency.