Multi-Scale Modeling and Simulation of DFIG-Based Wind Energy Conversion System

Abstract

A multi-scale transients model of a doubly fed induction generator (DFIG)-based wind energy conversion system (WECS) is developed, implemented, and validated. All ac circuit and control quantities of the electrical part are modeled by analytic signals rather than just real signals. In addition to the real parts, the analytic signals also comprise orthogonal imaginary parts. While measured Fourier spectra of real ac quantities involve positive and negative frequency components, they only involve positive frequency components when extended and represented as analytic signals. With the introduced shift frequency operator, the analytic signal can now be shifted in the frequency domain to reduce its maximum frequency contents and thus allow for a larger timestep size in accordance with the Nyquist criterion. If the shift frequency is set equal to the ac fundamental frequency, then the affiliated ac voltages and currents become dynamic phasors. At a zero shift, however, instantaneous signals can be tracked as in an electromagnetic transients program (EMTP). This is illustrated here for the voltage sourced converters (VSC) of the WECS. By appropriate selection of the shift frequency, both electromagnetic and electromechanical transients are simulated efficiently. Studies involving wind power fluctuations, three-phase-to-ground fault and single-phase-to-ground fault confirm these claims. Index Terms-Doubly fed induction generator (DFIG), electromagnetic transients, electromechanical transients, multi-scale, interface, voltage-sourced converter (VSC), wind energy conversion system (WECS).

Wave Function and Multiscale Modeling of MMC-HVdc System for Wide-Frequency Transient Simulation

“…where ς = ∆t(k)/∆t(k − 1). On the other hand, the ac quantities with a carrier are calculated by predicting the carrier and shifted phasor separately [21] as…”

“…In recent years, a lot of effort has been devoted to multiscale modeling of the PE-based devices such as two-level VSC. In [20], [21], the multi-scale models of two-level VSC were implemented where the SFM and AVM are alternatively used to modulate the EMTs and electromechanical transients respectively. It was found that the transitions between both models may lead to unpredicted numerical oscillations, not being directly applied in MMC multi-scale modeling.…”

Multi‐rate co‐simulation of power system transients using dynamic phasor and EMT solvers

“…The challenge in this context is the representation of fast phenomena such as those in power electronic converters in power systems. The transition between EMT and phasor solutions is realised through the application of switching functions [9, 10]. A problem still to be addressed is the integration of power electronic converter models that accurately represent devices inside the converter.…”

Analysis and Application of Quasi-Static and Dynamic Phasor Calculus for Stability Assessment of Integrated Power Electric and Electronic Systems

“…In DPC, the electric network is described through a set of differential rather than algebraic equations, thus being more accurate than QPC models [20]- [26]. DPC-based models have been applied to simulate a broad range of transients in different systems, including unbalanced distribution systems [27], microgrids [25], transients of electric machines [20], [28], and power electronic systems [26], [29], [30]. In all these applications, DPC-based models have demonstrated a good performance for representing the transients under study.…”