Transient Performance Comparison of Modified VSG Controlled Grid-Tied Converter

Distributed generators based on Virtual Synchronous Generator (VSG) control strategy reduce the maximal frequency deviation at the cost of increasing power oscillation. Different with a real synchronous generator, parameters and the swing equation of VSG can be modified flexibly to enhance the transient response of VSG. In this paper, two indicators are proposed to evaluate performance of VSG transient response. Besides, based on modified moment of inertia, a modified VSG is proposed. Theoretical analysis and experimental comparison between modified VSG methods is achieved. The experimental results show that the proposed indicators are effective to evaluate the oscillation phenomenon of various VSG methods and the transient performance of proposed modified VSG method is improved in contrast with existing ones: the power response overshoot is decreased from 45.1% to 16.5% and the frequency deviation peak is lowered from 0.0707 Hz to 0.0645 Hz. It is beneficial to improve both the transient performance of frequency deviation suppression and power regulation by the proposed modified VSG method.