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• An optimal design method in the Extended Harmonic Domain of the LCL filters. • Quantitative and qualitative assessment of different LCL filter design methods. • A Review of Passive Power Filters. • A Matlab graphic user interface (GUI) for the design of LCL filters. This paper presents a design method based on the extended harmonic domain modeling for L and LCL passive filters of active-front-end PWM two-level voltage source converters for grid-connected renewable energy sources. The proposed design method is tested under several operating scenarios, such as high and low power levels and switching frequencies. Also, a dedicated graphical user interface (GUI) with five other design methods is provided to ease the evaluation of the proposed design method. The GUI also computes the power quality indexes and the steady-state waveforms for each design methodology. In addition to this, an in-depth overview of filtering technologies and applications is presented to identify the primary practical use of passive filtering and to justify the use of LCL filter in grid-connected systems. The obtained results show that the proposed design method leads to the smallest passive filter parameters, and it is the only method that fulfills all the imposed power quality requirements as well as power specifications. [ABSTRACT FROM AUTHOR]

This paper deals with a battery energy storage system (BESS) in only one of its multiple operating modes, that is when the BESS is charging the battery bank and with the focus on the control scheme design for the BESS input stage, which is a three-phase LCL-filter PWM rectifier. The rectifier's main requirements comprise output voltage regulation, power factor control, and low input current harmonic distortion, even in the presence of input voltage variations. Typically, these objectives are modeled by using a dq model with its corresponding two-loop controller architecture, including an outer voltage loop and a current internal loop. This paper outlines an alternative approach to tackle the problem by using not only an input–output map linearization controller, with the aim of a single-loop current control, but also by avoiding the dq modeling. In this case, the voltage is indirectly controlled by computing the current references based on the converter power balance. The mathematical model of the three-phase LCL-filter PWM rectifier is defined based on the delta connection of the filter, which accomplishes the requirements of a 100 kW BESS module. Extensive simulation results are included to confirm the performance of the proposed closed-loop control in practical applications. [ABSTRACT FROM AUTHOR]