Woodbury Matrix Update Method for Inverse Admittance Matrix Formulation in Real-Time Simulation of Power Electronic Circuits

Computational complexity and storage are the two main constraints while performing real-time simulation of power electronic circuits. Matrix inversion in each time step required by nodal analysis based solvers is generally not possible in real-time simulation. Instead, the inversion of system matrix is computed and stored before the actual simulation starts. When there are several switches in the circuit being simulated, it is required to store 2 power N matrices (for N switches), and storage can become a bottleneck. In this paper, a new scheme is proposed wherein only a single inverse admittance matrix is required to be stored (for N switches), which is updated using Woodbury formula to obtain the inverse admittance matrix for the current switch states. The computational cost can be further reduced if more inverse admittance matrices are allowed to be stored. The proposed scheme is demonstrated with case studies of a few representative examples.