The Study Of Waveform Relaxation Method For Parallel Transient Stability Simulation

The calculation of transient stability of power system is very time-consumingand most calculation time has been spent at the solution of sparse linear equations, soit is very significant for speeding up the computation process adopting the sparsetechnology. MPI is the standard of message passing and it provides various functionswith high performance. The efficiency of parallel program can be improved if MPI isused properly. Now it is still impossible to realize the on line real-time simulation ofthe electromechanical transient process of large power systems and paralleltechnology might be one of potential methods for such a difficult problem. The mainwork of this thesis is as follows:Efficiency of two sparse technologies namely storage of array and storage oflinked list applied to Newton power flow calculation has been studied firstly. Thedifferences of memory overheads of the two modes have been also analyzed. Memoryanalysis and test results with different scale systems indicate that: when the modifiedlinear equations are solved with Gauss elimination with column pivots, the storage oflinked list occupies a little more memory, but saves much more time than that of array;the storage of linked list is even more superior to that of array if the system is ratherlarge. However, the calculation speed of the storage of linked list is only a little fasterthan that of the storage of array while the modified linear equations are solved withLDU factorization.The basic concept of MPI is introduced in brief, while two types ofcommunication of MPI namely point to point communication and collectivecommunication are presented in detail. Moreover, the methods of improvingcommunication efficiency are addressed in brief.An algorithm of parallel simulations of transient stability namely waveformrelaxation has been studied in this thesis and implemented at a powerful PC-Clustersystem. A new decomposition strategy for power systems is presented. The speed ofconvergence has been improved through introducing initial estimation instead ofusing last window voltage waves for border nodes at the beginning of time window ofbeing calculated. The longer the time window is, the more remarkable the effect is.The simulation results of Huabei power system indicate that the simulation time isshortest when the time window is one time step for the power system.