Design Oriented Analysis of Control Loops Interaction in Power Synchronization-based Voltage Source Converter

Power synchronization mechanism is coupled with the dc-link, since both synchronization and dc-link dynamics depend on the active power. The active power filter used in the frequency droop is correlated with inertia emulation, which affects the dc-link voltage. Furthermore, the coupling between active and reactive power in the low-voltage grid suggests a possible interaction between dc-link and reactive power control. The strong coupling between all the control loops and the dc-link in power synchronization-based converters represents a challenge both for the stability and for the controller tuning. This paper addresses the tuning of power synchronization-based converter with consideration of all the control loops interactions. A complete converter state-space model is derived, and a step-by-step tuning procedure based on eigenvalue analysis is proposed. Experimental results are provided to demonstrate the method.