PhD programme
by Lihui Yang
Guest PhD student from Xi’an Jiaotong University, China
Period
March 2006 – March 2010
Supervisor, China
Professor Xikui Ma,
School of Electrical Engineering,
Xi’an Jiaotong University
Supervisors, Denmark
Professor Jacob Østergaard, CET, DTU Electrical Engineering
Associated Professor Zhao Xu, CET, DTU Electrical Engineering
Abstract
The Doubly-fed Induction Generator (DFIG) equipped wind turbine is currently the most popular one due to its high energy efficiency, reduced mechanical loads on the wind turbine and relatively low power rating of the connected power electronics converter. Increasing penetration level of wind power generation of DFIG type into the grid will give impact to the power system performance. As stability is a key issue, it is necessary and imperative for the power system engineers to understand in essential how the DFIG wind generator system affects an existing interconnected power system stability.
The presented work is a part of the whole PhD programme. The purpose of this part of work is to examine the stability problem of the vector-controlled DFIG from a bifurcation perspective. The slow-scale bifurcation phenomenon is observed in simulation study. A detailed mathematical model of DFIG under closed-loop vector control is derived and used to analyze the observed bifurcation. Eigenvalue analysis is carried out to explore the essence of the instability and to study the effect of parameter variations on system stability. To facilitate design, stability boundaries in terms of variations of some practical design parameters are also identified.
Link
2008-11-09 Lihui Yang