Modeling method of sequence admittance for three-phase voltage source converter under unbalanced grid condition

• Main Authors: Yang CEN, Meng HUANG, Xiaoming ZHA
• Format: Article
• Language: English
• Published: IEEE 2018-03-01
• Series: Journal of Modern Power Systems and Clean Energy
• Subjects: Unbalanced grid voltage; Three-phase voltage source converter; Harmonic linearization; Positive and negative sequence admittance; Stability
• Online Access: http://link.springer.com/article/10.1007/s40565-018-0399-z

Abstract The admittance is a strong tool for stability analysis and assessment of the three-phase voltage source converters (VSCs) especially in grid-connected mode. However, the sequence admittance is hard to calculate when the VSC is operating under unbalanced grid voltage conditions. In this paper, a simple and direct modeling method is proposed for a three-phase VSC taking the unbalanced grid voltage as a new variable for the system. Then coupling in the three-phase system can be calculated by applying the harmonic linearization method. The calculated admittance of three-phase VSCs is verified by detailed circuit simulations.