A Novel Source-Side Virtual RLC Damping Approach to Mitigate DC Bus Voltage Oscillations in Cascaded System of DC Microgrids

Point-of-Load (POL) converters supply a constant output voltage to DC/AC loads. They regulate output tightly and adjust input current to meet constant power demand. This makes their input behave like a Constant Power Load (CPL). When connected through a source converter, POLs can destabilize the system. This happens due to negative incremental impedance, leading to voltage oscillations in the DC bus. The cause is the impedance interaction between POLs and source converters. To solve this, the paper proposes a source-side Adaptive Virtual Resistance-Induced Capacitive (AVRLC) control strategy. A virtual RLC damper is added in parallel with the source converter's capacitor. This method allows simple and effective control parameter tuning. It preserves the dynamic performance of the load converter. The adaptive control adjusts to load current changes, enhancing flexibility and stability. The control strategy is tested on three cascaded DC/DC converter systems supplying CPLs. Its effectiveness is verified using MATLAB®/Simulink simulations.