An improved relaxation based spatial domain decomposition method for parallel transient stability simulation

Transient stability assessment by time domain simulation is an indispensable module in Dynamic Security Assessment application employed for maintaining power system security and reliability. Due to continuous expansion and imposition of new complexities, reduction in time required for the simulation of system dynamics is vital for both grid operation and planning. This paper proposes a domain decomposition methodology employing spatial parallelism based on relaxation conditions to speedup transient stability simulations to handle the aforementioned challenge. Since convergence is an issue in relaxation methods, in this work, a convergence enhancing mechanism involving admittance parameters of fictitious networks which mimic the rest of the system for each decomposed smaller network is derived. The proposed method, improves the convergence property of the Parallel Update Relaxation algorithm employed for the concurrent simulation. Also, a technique of port dependency reduction, which guarantees convergence for any general network is presented. The accuracy of the proposed algorithm is validated on a 9-bus system. For the purpose of measuring the performance metrics of the algorithm, two large test cases comprising of 39936 and 79872 buses are considered. Results corroborate the scalability and improved speedup features of the methodology which achieves a significant reduction in the simulation execution time.