Power-Hardware Design and Topologies of Converter-Based Grid Emulators for Wind Turbines

Abstract

Power-electronic-based grid emulators (GEs) emerge as a favorable method for testing grid-code compliances of wind turbines (WTs), thanks to their full controllability and improved efficiency. To accommodate the increasing power and voltage levels of WTs, scalability becomes a critical requirement for the topologies of converter-based GEs. This paper identifies first the power rating of future GEs based on the system architecture and the evolution of WTs, followed by evaluating converter topologies of GEs for high scalability. Design considerations of power semiconductor devices, step-up transformers, dc chopper and dc capacitors are also discussed for existing and prospective GEs.

Functional Specifications and Testing Requirements of Grid-Forming Offshore Wind Power Plants

“…Various next-generation PHiL test benches have been proposed in (Curran et al, 2022;Neshati et al, 2023;Li et al, 2023;Gevorgian et al, 2023). These test benches use only a few selected components to represent the rest of the equipment by employing novel modelling and emulation techniques for the missing hardware parts.…”

“…On the other hand, the use of grid emulators is also rising (Li et al, 2023;Hans et al, 2022Hans et al, , 2023 on tests performed at the equipment level, where instead of connecting the equipment directly to the system, grid emulators are connected to the equipment. This allows for a larger variety of tests and more controllability of testing conditions, as the grid emulator can respond to any desired setpoints and operating conditions.…”

Adaptive Anti-Saturation Control Design of Transformers in Converter-Based Grid Emulators

“…Fig. 2(b) depicts the magnetic curve of the transformer with four critical points [2], where 0, r, s and p denote the initial flux, residual flux, saturation flux and maximum flux, respectively. im0, imr, ims and imp are the magnetizing current at each of these flux points.…”

Adaptive Anti-Saturation Control Design of Transformers in Converter-Based Grid Emulators

“…Fig. 2(b) depicts the magnetic curve of the transformer with four critical points [2], where 0, r, s and p are the initial flux, residual flux, saturation flux and maximum flux, respectively. im0, imr, ims and imp denote the magnetizing current at each of these flux points.…”

“…For normal operation, j can be a fundamental frequency signal j_ac without dc deviation [2], [5]. However, when emulating grid fault events, the step changes of voltage magnitude and phase angle tend to induce an additional dc flux component j_dc into j, especially during the fault recovery process [7].…”