Study Of Recognition Of Dangerous Lines Casued By Power Flow Transferring In Multi-Branches Removal Event And Overload Elimination Control Strategy

In order to ensure normal production and living of the masses and to avoid huge losses of the national economy in the condition that the electric power industry and the scale-up of network were developing flourishly,the security and stability of the power system should be paid more attention so that the chain trips or blackouts couldn't be occurred Therefore,the estimation of power flow transferring amount and identification of dangerous lines in multi-branch broken accident,and overload control were the focues in this thesis,which is beneficial to guarantee the security of the power system.Firstly,a new algorithm for calculating power transferring amount based on variable adjacency matrix construction was proposed.In the bases of generation methods of directed paths in graph theory,transferring amount was easily accessed by simple inversion of variable adjacency matrix composed of branch breaking distribution factor in single-line broken,while broken lines and normal lines were equaled by nodes.In this method,the power flow increment could be produced by an inverting operation of variable adjacency matrix,which was one more dimension than broken line number.Modification of node susceptance matrix were unnecessary,and the calculation is small which means a high-speed management.Secondly,the determining way of dangerous lines in multi-branch broken power flow transferring was given according to the calculating principle of transferring power.Power transferring amount has a liner relation with the breaking distribution factor while all lines broken separately,which means the set of lines affected seriously could be determined by searching the first K paths of each broken line independently.The difference of broken lines was considered in searching number programmer.Large amount of unnecessary calculation were avoided and the searching path number was not to large so that searching would be finished quickly,which were realized by reducing the threshold of individual searching of each broken line.Thirdly,a method was designed to select control node and determine security constraint set when sensibility way was utilized to overload control.Adjustment nodes were selected according to the projection values of node sensitivity vector on optimal sensitivity vector that was determined by circuit overload power and thermal power limit.a way of security constraint determining was given based on the optimal sensitivity vector.Adjustment amount calculation could be figured fast and the amount accompany with control rounds could be smaller in which modified way for nodes select and security constraint set determination were applied.Finally,a method to determine the security constraint when the optimization algorithm was utilized to deal with emergency control problem was proposed.The definition and calculation ways of involved line that represents the extent of variation were suggested,and then the K-means clustering was applied to solve involved lines set.Security constraint set was constituted by Combining the involved lines with lines whose power were closed to limit power,moreover,the non-linear programming was obtained to solve the active power safety model,which adopted the strategy that the control node was increasing layer by layer.The number of adjustment equipment and optimization variables were reduced and the efficiency of emergency control were improved largely.A large number of simulation results of IEEE39 and IEEE118 system verified the accuracy and effectiveness of the proposed method.