Optimized and coordinated model predictive control scheme for DFIGs with DC-based converter system

Abstract

This paper proposes an optimized and coordinated model predictive control (MPC) scheme for doublyfed induction generators (DFIGs) with DC-based converter system to improve the efficiency and dynamic performance in DC grids. In this configuration, the stator and rotor of the DFIG are connected to the DC bus via voltage source converters, namely, a rotor side converter (RSC) and a stator side converter (SSC). Optimized trajectories for rotor flux and stator current are proposed to minimize Joule losses of the DFIG, which is particularly advantageous at low and moderate torque. The coordinated MPC scheme is applied to overcome the weaknesses of the field-oriented control technique in the rotor flux-oriented frame, which makes the rotor flux stable and the stator current track its reference closely and quickly. Lastly, simulations and experiments are carried out to validate the feasibility of the control scheme and to analyze the steady-state and dynamic performance of the DFIG.

Transient stability enhancement of DC-connected DFIG and its converter system using fault protective device

“…1, and has been widely applied in DC-interfaced wind farms [27,[29][30][31]. It consists of a rotor side converter (RSC) and a stator side converter (SSC).…”

“…With the increasing use of DC transmission, DC-based DFIG systems have been widely applied in a DC grid [25][26][27]. A diode-based stator converter interfaces a DFIG with a DC grid, which simplifies its converter structure, reduces its cost and improves its efficiency [26,28], however this diode-based converter has no protective ability and exposes the DFIG to DC grid faults.…”

“…A diode-based stator converter interfaces a DFIG with a DC grid, which simplifies its converter structure, reduces its cost and improves its efficiency [26,28], however this diode-based converter has no protective ability and exposes the DFIG to DC grid faults. An IGBTbased stator converter is a promising DC-based converter which connects a DFIG to a DC grid directly with lower levels of current harmonics and higher power quality [27,[29][30][31], but its protective ability is insufficient during serious DC grid faults.…”

Predictive Torque and Rotor Flux Control of a DFIG-DC System for Torque Ripple Compensation and Loss Minimization

“…An early study reported in [8] for an ac stand-alone DFIG feeding non-linear loads proposed to compensate for the harmonics by operating the grid-side converter (GSC) as an active filter. As the DFIG-dc system does not include any GSC, the only way to implement an active filter is by adding an extra converter [9], or replacing the diode-bridge with a second VSI, which turns the system into a dual-VSI DFIG [10]- [11]. Twelve-pulse rectifiers are another viable option to tackle the harmonics at the source [12].…”

Maximum Power Point Tracking of DFIG with DC-Based Converter System Using Coordinated Feedback Linearization Control

“…But harmonic may reach from 5.97% to 11.66% [8]. An IGBT-based converters system consisting of a rotor side converter (RSC) and a stator side converter (SSC) connects rotor and stator with DC grid, respectively [9][10][11][12][13]. This structure has the advantages that it can reduce the current harmonic effectively and regulate the stator flux and current flexibly according to the needs of the system, not limited to AC grid.…”