A Systematic Approach to DC-Bus Control Design in Single-Phase Grid-Connected Renewable Converters

This paper presents a method for design and control of dc-bus capacitance and transients in a renewable single-phase grid-connected converter. Conventionally, a proportional (P) or proportional-integrating (PI) controller is commonly used and the design stage is performed using trial-error or using a simplified analysis that does not take the dynamics of the current control loop into consideration. This paper proposes 1) a systematic and efficient method for design of dc-bus PI controller gains; and 2) an accurate method for the design of the dc-bus controller gains without neglecting the dynamics of the current control loop. Two main objectives are to have control over the amount of output current harmonics and over the level of bus fluctuations caused by random input power swings. The proposed method is transparent and it provides a convenient and rigorous insight for the designer to properly select the size of dc-bus component and to determine the controller gains.