In this paper the diakoptics-based branch-tearing method for solving large electric networks, known as the Multi-Area Thévenin Equivalents (MATE), is combined with the alternating method for parallelizing the transient stability simulations of bulk power systems. In the proposed framework, equations associated with dynamic and static devices and passive network are distributed among computing processes. The paper discusses an implementation of the parallel transient stability simulator along with results for two power systems with about 4,000 and 15,000 buses, both based on the Brazilian Interconnected Power System. Performance metrics for assessing the effectiveness of the proposed methodology are also presented and discussed. In order to validate the implementation, the results are also compared with those from an industrial-grade transient stability program, ANATEM developed by CEPEL.

The Multi-Area Thévenin Equivalent algorithm (MATE) partitions a network into a number of subnetworks connected by links. The solution proceeds in two stages: first the subnetworks are solved independently, with the links open, and then the system formed by the links is solved with the subnetworks represented by their Thévenin equivalents as seen from the link nodes. In this paper, an overview of the MATE technique for solving large power systems on parallel computing architectures will be discussed, along with a performance analysis and applications, including the solution of the WECC system (about 15,000 nodes and 17,000 branches), which was achieved with a 7-time speedup with respect to a sequential sparsity-oriented algorithm. Comparisons with another parallel sparse solver are also presented.