Cooperative Rotor-Side SMES and Transient Control for Improving the LVRT Capability of Grid-Connected DFIG-Based Wind Farm

This paper presents a novel scheme to enhance low voltage ride through (LVRT) capacity of a 5 × 1.5 MW doubly-fed-induction-generator-based (DFIG-based) wind farm. One superconducting magnetic energy storage (SMES) unit is introduced to connect in parallel with the rotor side of each DFIG. Two LVRT strategies of inductance emulating control and transient voltage control are used in the SMES energy storage side converter and rotor side converter, respectively. Comprehensive simulations and performance evaluations are carried out in both the symmetrical and asymmetrical grid fault cases. The results show that the proposed scheme can not only protect the key parameters of each DFIG unit, but also enhance the grid voltage effectively under different fault initial angles.

I. Introduction

Doubly fed induction generator (DFIG) has a number of unparalleled advantages, which makes it become an excellent choice for many wind power operations [1]. However, its weakness of low voltage ride through (LVRT) capacity and the fluctuation of output power are two crucial problems in modern power systems [2], [3].