Multidisciplinary Control Scheme based Capacitor Voltage for LCL Filtered Grid Connected Converter

Grid-connected converters employing LCL filters for grid interface experience resonance peaks issue which affects the system control and stability. In this paper, a multidisciplinary control scheme that can mitigate resonance raised by interaction between LCL filter and grid inductance particularly for weak grid scenarios of widely varying parameters is presented. Besides, the proposed controller provides improved low order harmonics rejection capability and maintains system stability. The proposed method relies on using capacitor voltage feedback to counteract the influence of grid impedance parameters variations on the system performance. In order to maintain system stability for the entire range of grid parameters and concurrently provide effective resonance damping, a design approach for the grid inner current controller is obtained. The system robustness, bandwidth and harmonics rejection capabilities are explored. The significance of the proposed active damping method is explored via frequency domain analysis and time domain simulation under different operating conditions.