Stability Analysis of Converter-Dominated Power Systems by Phasor-Based and Electromagnetic Transient Simulation

Abstract:
The objective of this paper is a comparative analysis of high-voltage power system stability with high penetration of converter-based generation, employing both the phasor-based (stability, RMS) and electromagnetic transient (EMT) sim-ulation types. An average-value model and a phasor model of a modular multilevel converter (MMC) are incorporated into the CIGRE Benchmark System for Network Integration of Renewable and Distributed Energy Resources, which permits a comparative analysis between the simulation types. The depth of the AC side converter model is identical for both simulation methods and includes the upper- and lower-level controls. In contrast, the DC side is excluded from the RMS simulation. In order to simulate a fully converter-dominated power system, a grid-forming control based on a virtual synchronous machine is implemented in addition to the grid-following control. The level of penetration of converter-based power generation and grid-forming elements is gradually increased. The Prony-Based Oscillation Index (PBOI) evaluates the differences in oscillation behavior. The simulations are carried out in PSS(r)SINCAL/NETOMAC. The re-sults indicate that for power systems comprising a significant portion of grid-forming elements, the RMS simulation demonstrates identical dynamic behavior to that observed in EMT simulations, particularly with regard to the power oscillations of the power system. In contrast, with a low proportion of grid-forming elements, the RMS simulation exhibits numerical instabilities more frequently than the EMT simulation.