Power Quality Improvement in a Cascaded Multilevel Inverter Interfaced Grid Connected System Using a Modified Inductive–Capacitive–Inductive Filter with Reduced Power Loss and Improved Harmonic Attenuation

Abstract

Recently, multilevel inverters are more researched due to the advantages they offer over conventional voltage source inverters in grid connected applications. Passive filters are connected at the output of these inverters to produce sinusoidal waveforms with reduced harmonics and to satisfy grid interconnection standard requirements. This work proposes a new passive filter topology for a pulse width modulated five-level cascaded inverter interfaced grid connected system. The proposed passive filter inserts an additional resistance-capacitance branch in parallel to the filter capacitor of the traditional inductive–capacitive–inductive filter in addition to a resistance in series with it to reduce damping power loss. It can attenuate the switching frequency harmonic current components much better than the traditional filter while maintaining the same overall inductance, reduced capacitance and resistance values. The basic parameter design procedure and an approach to discover the parameters of the proposed filter is introduced. Further, a novel methodology using Particle Swarm Optimization (PSO) is recommended to guarantee minimum damping loss while ensuring reduced peak during resonance. In addition, PSO algorithm is newly employed in this work to maximize harmonic attenuation in and around the switching frequency on the premise of allowable values of filter inductance and capacitance. A comparative discussion considering traditional passive filters and the proposed filter is presented and evaluated through experiments conducted on a 110 V, 1 kW five-level grid connected inverter. The modulation algorithm for the multilevel inverter is implemented using a SPARTAN 6-XC6SLX25 Field Programmable Gate Array (FPGA) processor. The analysis shows that the proposed filter not only provides decreased damping power loss but also is capable of providing considerable harmonic ripple reduction in the high frequency band, improved output waveforms and lesser Total Harmonic Distortion (THD) with improved power quality for the multilevel inverter based grid connected system.

On the Performance Optimization of Two-Level Three-Phase Grid-Feeding Voltage-Source Inverters

“…The total power losses P T in three-phase module under sinusoidal pulse width modulation (SPWM) are shown in Equation (8).…”

“…In the literature [7][8][9][10][11], switching frequency was used either to improve the inverter efficiency [7,9] or the quality of the output power [10,11]. The fixed switching frequency for all conditions was considered in [5] at the maximum possible total harmonic distortion (THD), and in [11] the trajectory of the switching frequency was stated for the single phase inverter based on the calculus of variations.…”

“…In [10], the switching frequency was selected to minimize the acoustic noise of the three-phase induction motor. The switching frequency is used in [8] to analyze and design the LCL filter in the grid-connected, cascaded, multilevel inverter to improve harmonic attenuation and reduce the damping power loss.…”

Experimental Investigation on the Performances of a Multilevel Inverter Using a Field Programmable Gate Array-Based Control System

“…Several papers in the literature have focused their attention in the field of multilevel converters controlled by FPGA, especially for high-speed control systems [7][8][9][10][11][12][13][14][15][16][17][18]. For instance, Islam et al [8], as well as Zhou et al [9], proposed the modeling and experimental evaluation of multilevel inverters control, focusing their interest towards the implementation through FPGA and not on the harmonic content of the voltage waveform for the different modulation techniques.…”

Mechanism Analysis of PCC Harmonic Resonance Based on Nonlinear Self-Oscillation Concept in a High-Power Grid-Tied Photovoltaic Plant

“…The parameters of equivalent admittance/impedance of fundamental and harmonics of these equipment exist in uncertainty, which will significantly change the harmonic network admittance matrix of micro-grid [20]. Due to the rapid increase of photovoltaic systems in micro-grids, the problem of power quality associated with the intermittent nature of these systems had become more and more serious, and many efforts have been made already [21,22]. Most of the strategies about harmonic suppression in micro-grid focus on the power grid models containing one PV inverter, hence it is necessary to establish a model associated with a multi-inverter-based micro-grid [23,24].…”