Impact of current-controlled voltage source converters on power system stability

摘要

It is known that current-controlled voltage source converters do not contribute to the inertia of power systems, leading to a higher rate of change of frequency in case of power imbalances. Another fundamental effect becomes apparent in case of large phase angle jumps of the grid voltage. Such phase angle jumps may occur, for example, in consequence of a system split. The power infeed of the converter depends on the estimated phase angle and, hence, is transiently influenced by the inherent delay of its estimation, usually by a phase-locked loop (PLL). This paper investigates the effect of the PLL dynamics on the converter behavior and its impact on transmission system voltage and frequency stability. To this end, islanding scenarios of a grid with lines loaded beyond their natural power are considered. Sensitivity analyses of the PLL parameters show noticeable effects on voltage and frequency stability depending on the dynamic parameterization of the PLL.