Study on Reducing the Parallel Overhead of the BBDF Method for Power System Transient Stability Simulations

In the power system parallel transient stability simulation (TSS), the parallel overhead will rise significantly with the increase in concurrency, which will seriously affect the efficiency of parallel computing. However, there are relatively few studies on the parallel overhead in the power system research field at present. In this paper, the geneses of the parallel overhead are introduced from the point of view of computer technology. The composition of the parallel overhead of the bordered block diagonal form (BBDF) method and the nested BBDF (NBBDF) method of the power system parallel TSS is analyzed. The time consumption of computing tasks and the parallel overhead of the BBDF method and the NBBDF method implemented by message passing interface (MPI) and OpenMP under different thread scheduling patterns are tested in detail in the 2383wp system and two practical power systems (13 490 node and 24 886 node). On this basis, an efficient implementation of the NBBDF method based on subnet-core mapping and mixed programming of MPI and OpenMP is suggested, which can further reduce the parallel overhead and increase the speedup ratio to more than 17x with 64 cores in the 24 886-node system. At last, some rules are summarized based on the test results.