An adaptive DC-bus stabilizer for single-phase grid-connected renewable energy source system
This paper proposes an adaptive DC-bus stabilizer for single-phase grid-connected voltage source converter (VSC) with small-scale renewable energy integration. To enhance converter's power density, the conventional active power decoupling (APD) techniques were adopted to reduce the DC capacitance by compensating the inherent second-order harmonic power ripples in the single-phase VSC. However, it would potentially make the DC voltage vulnerable to transient power ripples, which is a critical issue for the grid-connected renewable energy source (RES) system during grid faults. The proposed DC-bus stabilizer can not only compensate the second-order harmonic power ripples at normal operation, but also enhance the fault ride-through capability of the converter. The circuit topology and its corresponding control strategy are presented, and then simulation results are provided to demonstrate the feasibility and validity of the proposed DC-bus stabilizer under normal operation and grid fault condition.