RELAXATION-NEWTON METHODS FOR TRANSIENT STABILITY ANALYSIS ON A VECTOR PARALLEL COMPUTER

In this paper, the implementation of transient stability analysis prog rams on a vector/parallel computer is considered. The windowing techni que is adopted. The parallelism-in-time is exploited by using the Gaus s-Jacobi or the Gauss-Seidel methods to relax the dependency between t ime steps within a time window; the Newton method is employed to solve the discretized equations corresponding to each time step exploiting the parallelism-in-space. The computation of the bus voltage and state variables pertaining to different time steps is carried out in parall el by the processors available. A reordering of the operations relativ e to the synchronous machine equations is introduced to obtain an effi cient use of the vector hardware of the computer. The W-matrix method is employed to solve the network equations. Test case simulations are performed for the IEEE 118 bus system and two US networks with 862 and 904 buses using a 4-processor CRAY Y-MP8/464 computer. The proposed v ector/parallel programs achieve substantial speed-ups over a scalar re ference program based on the Very Dishonest Newton method. The synergy between vector and parallel processing allows speed-ups in excess of 22 to be attained for the US 904 bus network; run times are always sho rter than the simulation interval. Best results are obtained by implem enting the recently proposed travelling window approach. Thanks to a s uitable task partitioning, the apparently sequential Gauss-Seidel appr oach is demonstrated to be an effective alternative to the Gauss-Jacob i relaxation scheme.