Voltage Source Converter Control and Stability Analysis of VSC-HVDC System with High DC-Link Impedance

Quantitative criteria of considering AC infeed in DC fault assessment of modular multilevel converters

“…To achieve better dynamic performance and adequate speed response of the inner control loop, modulus optimum is conventionally used for tuning the current control parameters due to the fast response and simplicity [30][31][32][33]. The PI parameters then can be written as [ Ta is defined as 1/(2fsw) [30,31], where fsw is the switching frequency of the converter. Since fsw is usually large enough for the system to achieve ideal modulation, the closed loop transfer function can be simplified as [22] * * ( )…”

“…Since V dcN 2 (LP N ) ⁄ =345.1, which is smaller than ki, the second criterion is used to determine the impact of AC infeed. According to (30), 1-( √ 1+K 2 Q) ⁄ is calculated as 6.6%, which is smaller than σ max . The AC infeed can be neglected.…”