Evaluation of Phase Imbalance Compensation for Mitigating DFIG-Series Capacitor Interaction

Abstract

This paper assesses the suitability of the phase imbalance concept as an alternative approach for series compensating a transmission line, with the goal to eliminate adverse subsynchronous interactions between a DFIG and the transmission system. The performance of this concept, under a predefined degree of asymmetry, is compared with the classical series compensation scheme. First, it is concluded that the phase imbalance concept can reduce subsynchronous oscillations, as this concept results in lower resonance frequencies, which in turn lead to increased damping. Second, as these resonance frequencies remain in the DFIG's negative resistance region, the subsynchronous oscillations cannot be fully mitigated.

Systematic Procedure for Mitigating DFIG-SSR Using Phase Imbalance Compensation

“…The classical double loop control was used as control structure of the rectifier and inverter. The implemented controls are the same as the ones used in the authors' previous work [16]. Since the controls presented in the IEC standard are meant for root mean square applications, several adaptations were implemented to make the model applicable for EMT analysis.…”

“…(1) is the mathematical analytical model that describes the relation between the degree of asymmetry ( ), the compensation level ( ) and the corresponding shift in resonance frequency (Δ ) for the one phase series PIC and is given in the footnote 1 . See [16] for the full derivation of (1).…”