Robust Stability Analysis of a LCC-HVDC System Connected with Wind Farms

The small-signal stability of a line-commutated converter based high voltage direct current (LCC-HVDC) system connected with wind farms (WFs) is a challenging issue in modern power systems. Most of researches focus on the absolute stability based on different stability criteria, and it has not pay much attention yet to quantify the relative stability. This paper proposes a new stability index based on the
$\nu$
-gap metric, i.e. the robust stability margin, to quantify the relative stability of a LCC-HVDC system connected with WFs. We build a suitable multiple-input multiple-output (MIMO) model of a LCC-HVDC system connected with WFs represented by transfer function matrix first. Then, the robust stability margin of the system is calculated based on the
$\nu$
-gap metric. Moreover, according to the corresponding stability criterion, we present a method to easily calculate the stable region of control parameters in LCC-HVDC and WFs. Case studies based on the nonlinear model are given to demonstrate the effectiveness of the proposed method.