Parametric Stability Assessment of Singlephase Grid-tied VSCs Using Peak and Average dc Voltage Control

A type of peak-value dc voltage control (denoted as PK control) was proposed in the literature for supporting the use of a smaller dc-side capacitance when the single-phase Voltage Source Converter (VSC) is operated as a Static Synchronous Compensator (STATCOM). Although it was demonstrated to operate stably under several conditions, it will be revealed in this paper how the PK control will suffer from a more severe small-signal stability issue under non-ideal grid conditions than the conventional method of controlling the averagevalue of the dc voltage (denoted as Avr control). Especially, it will be shown how the PK control is sensitive to some of the control parameters. To obtain these results, a parameter-oriented stability analysis method is developed in the linear-time periodic (LTP) framework. Then, it is utilized for parametric stability assessments of the Avr and PK control. Finally, both frequency- and time-domain experimental results verified the effectiveness and accuracy of the applied method in the presented analysis.