$LCL$ Filter Design and Performance Analysis for Grid-Interconnected Systems

Abstract

The use of power converters is very important in maximizing the power transfer from renewable energy sources such as wind, solar, or even a hydrogen-based fuel cell to the utility grid. A LCL filter is often used to interconnect an inverter to the utility grid in order to filter the harmonics produced by the inverter. Even though there is an extensive amount of literature available describing LCL filters, there has been a gap in providing a systematic design methodology. Furthermore, there has been a lack of a state-space mathematical modeling approach that considers practical cases of delta and wye connected capacitors showing their effects on possible grounding alternatives. This paper describes a design methodology of a LCL filter for grid-interconnected inverters along with a comprehensive study of how to mitigate harmonics. The procedures and techniques described in this paper may be used in small-scale renewable energy conversion systems and may also be retrofitted for medium and large-scale grid connected systems.

Impact of Photovoltaic Tied to Electrical Grid System On Power Quality

“…LCL filters have been used in grid connected inverters. Where L1 is the inverter side inductor, L2 is the grid-side inductor; Cf is a capacitor with a series Rf damping resistor [10]. The inverter side and Grid inductor, and capacitor with series damping resistor Values for LCL filter were chosen as 1.449852 mH.…”

Design of a Four-Branch LCL-Type Grid-Connecting Interface for a Three-Phase, Four-Leg Active Power Filter

“…A lower impedance amplitude value indicates a higher APF output capacity, and vice versa. In the frequency domain, lower impedance amplitude means higher capacity in outputting high-order frequency current in some other conditions [19]. Because the impedance amplitude is proportional to its frequency within the output current frequency band, the dual-side impedance amplitude in the fundamental frequency is selected for this performance index in practical use, which is (L 1 + L 2 )ω 1 .…”

“…However, that study did not provide detailed design steps of decoupling or LCL parameters. There are two common types of grid-connecting interfaces: L-type and LCL-type [5,[10][11][12][13][14][15][16][17], whose functions can be summarized as two aspects: (1) transforming the voltage output from VSC into controllable current injected to the grid with little power loss and (2) filtering out the switching frequency harmonic current from the grid-injecting current, which is caused by the PWM-voltage output of the VSC [18,19]. Compared with the L-type grid-connecting interface, the LCL-type receives more utilization because it offers better harmonic attenuation and efficiency at a smaller size.…”

Development of a four phase floating interleaved boost converter for photovoltaic systems

“…An energy storage system (e.g., battery) connects through a bidirectional charge controller. An inverter is connected to produce AC power, with an LCL filter to limit the harmonics [9]. For gridconnected systems, this AC output would be connected to the utility grid.…”