A Novel Interfacing Technique for Distributed Hybrid Simulations Combining EMT and Transient Stability Models

The steady increase of power electronic devices and nonlinear dynamic loads in large-scale ac/dc systems desperately requires an efficient simulation method. However, the traditional hybrid simulation, which incorporates various components into a single electromagnetic-transient (EMT) subsystem, causes great difficulty in network partitioning and significant deterioration in simulation efficiency. To resolve these issues, a distributed hybrid simulation method is proposed in this paper. The key factor leading the success of this method is a distinct interfacing technique, which includes: 1) a new approach based on the two-level Schur complement to update the interfaces by taking full consideration of the couplings between different EMT subsystems; and 2) a combined interaction protocol to further improve the efficiency while guaranteeing the simulation accuracy. The improved performances of the proposed method in terms of efficiency and accuracy have been verified by the simulation studies on the modified IEEE 39 system as well as a practical ac/dc system, both of which consist of a two-terminal voltage-source converter HVdc and nonlinear dynamic loads.