A Semi-Analytical Approach for State-Space Electromagnetic Transient Simulation Using the Differential Transformation

Electromagnetic transient (EMT) simulation is a crucial tool for power system dynamic analysis because of its detailed component modeling and high simulation accuracy. However, it suffers from computational burdens for large power grids since a tiny time step is typically required for accuracy. This paper proposes an efficient and accurate semi-analytical approach for state-space EMT simulations of power grids. It employs high-order semi-analytical solutions derived using the differential transformation from the state-space EMT grid model. The approach incorporates a proposed variable time step strategy based on equation imbalance, leveraging structural information of the grid model, to enlarge the time step and accelerate simulations, while high resolution is maintained by reconstructing detailed fast EMT dynamics through an efficient dense output mechanism. It also addresses limit-induced switches during large time steps by using a binary search-enhanced quadratic interpolation algorithm. Case studies are conducted on EMT models of the IEEE 39-bus system and a synthetic 390-bus system to demonstrate the merits of the new simulation approach against traditional methods.