An Interface Method for Co-simulation of EMT Model and Shifted Frequency EMT Model Based on Rotational Invariance Techniques

TL;DR

The paper tackles the efficiency-accuracy tension in EMT simulations by combining SFEMT with traditional EMT through a new co-simulation interface. It develops a general SFEMT modeling framework and an ESPRIT-based analytical-signal construction to build true analytic envelopes from real signals, enabling accurate coupling between EMT and SFEMT models. The method provides a practical procedure to estimate signal components (count, frequencies, amplitudes, and phases) from short data windows and to reconstruct a low-frequency analytic envelope for SFEMT, ensuring positive-frequency content. Case studies on a modified IEEE 39-bus system demonstrate improved accuracy under harmonic content and inter-area coupling, highlighting the approach's potential for efficient, reliable multi-scale power-system co-simulation with wind farms.

Abstract

The shifted frequency-based electromagnetic transient (SFEMT) simulation has greatly improved the computational efficiency of traditional electromagnetic transient (EMT) simulation for the ac grid. This letter proposes a novel interface for the co-simulation of the SFEMT model and the traditional EMT model. The general form of SFEMT modeling and the principle of analytical signal construction are first derived. Then, an interface for the co-simulation of EMT and SFEMT simulation is proposed based on rotational invariance techniques. Theoretical analyses and test results demonstrate the effectiveness of the proposed method.

Figures (3)

• Figure 1: Schematic diagram of the modified IEEE 39-bus power system.
• Figure 2: Phase A current of the lines 26-25.
• Figure 3: Amplitude spectra of analytical signals obtained by different interfaces. (a) Original signal. (b) Delay transformation. (c) Second parallel simulation. (d) Proposed method.