Parametric Stability Assessment of Single-phase 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 average-value 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.