Virtual Impedance Based Control Scheme for Stability Emulation of Grid-Connected Converters

The grid-connected converters are becoming an important component of modern power grid, and the stability of grid-connected converters connected to the weak grid has drawn increasing attention. In order to validate the stability-related performances, the emulation of grid impedance/behaviors is becoming an emerging need. However, the existing approaches are difficult to achieve high-bandwidth and high-precision emulation for the resonance when converters are connected to the weak grid. In this paper, a testing approach for grid behaviors emulation is proposed. The proposed control scheme is composed of two modules, i.e., the impedance-forming modules (IFMs) and power-supporting modules (PSMs). The IFMs are introduced to achieve high-bandwidth virtual impedance, and the PSMs are responsible of power control. The performance of proposed emulator is verified by PLECS.