DC-Bus Design and Control for a Single-Phase Grid-Connected Renewable Converter With a Small Energy Storage Component

摘要

This paper presents a control design approach for optimum dynamic response in single-phase grid-connected renewable converters with minimum energy storage components. This is a crucial matter in realizing compact and robust converters without use of bulky and sensitive electrolytic capacitors. Nonoptimum dynamic response results in undesired interruptions of the maximum power point tracking and reduction of the overall efficiency of the system. Common practice is to select a large dc-bus size in order to reduce the double-frequency ripples that cause harmonics and to slow down the dynamic response to avoid large fluctuations on the bus caused by random input power jumps. This paper shows that both problems can be addressed to a great extent by improving the control system and without need to excessively increase the size of the bus component. This paper proposes a control system to achieve these goals and provides an analytical design method to optimize both dynamic response and output current harmonics. The proposed method succeeds to reduce the size of bus component several times without compromising the system performance. Details of the proposed method, mathematical modeling of the bus control and current control systems, simulations, and experimental results are presented and discussed.