LCL-filter design for low-voltage high-power grid-tied voltage-source converter considering various damping methods

The limited switching frequency, size and weight concerns, and the stringent limits for the injected grid current harmonics challenge the implementation of LCL grid filters for low-voltage multi-megawatt (multi-MW) renewable energy converters. Traditional design procedures of such filters employed in low power and high switching frequency converters may not hold for a multi-MW filter interfacing a low-voltage converter switching at low frequency to the electric grid. This paper proposes an LCL-filter design algorithm spanning a wide power range of multi-MW converters where impacts of favored current control method, damping method and pulse-width modulation (PWM) technique are reflected within the design phase. Filter design algorithm was tested under 0.5, 1, and 2-MVA applications. The impacts of designated damping and current control methods were elaborated in terms of dynamic and steady-state performance using 1-MVA converter design case.