High-Order Exponential Integrator Algorithm for Real-Time Simulation of Power Electronic Systems

Real-time (RT) electromagnetic transient simulation is growing in popularity for hardware-in-the-loop (HIL) simulation of physical hardware devices. This article proposes a variable-step high-order RT exponential integrator (RTEI) algorithm that is well suited for HIL studies, particularly for controller HIL studies with digital controllers. The RTEI algorithm relies on the precomputation of matrix exponentials to offload runtime complexity. The RTEI algorithm works at each intracontrol cycle and aims to only recalculate system states at switching events. The proposed solver flexibly adapts the number of forcing function terms to achieve high accuracy with a minimum number of computed points. The proposed algorithm is L-stable, making it generally applicable to power electronic systems. A case study validates the accuracy of the proposed algorithm by comparing it with hardware experimental results. Further case studies benchmark the computational efficiency of the proposed solver with a fixed-step Trapezoidal rule-backward Euler solver (TR-BE), ART5, and an existing discrete hybrid time-step (DHT) algorithm. It is shown that the proposed algorithm achieves over 10-fold and 2-fold efficiency increases in TR-BE and DHT, respectively. The advantages of the proposed algorithm lie in both efficiency increases for general circuit topologies and the stability of the algorithm in the presence of high network stiffness.