Order Power Filter Research Articles

Design and Analysis of a Higher Order Power Filter for Grid-Connected Renewable Energy Systems

Harmonic compensation is regularly implemented for a grid-tied inverter to reduce the influence of the grid current and voltage harmonics. In this study, the L(LCL) 2 filter, which is a high-order power filter for single-phase grid-tied voltage-source inverters, is designed and analyzed. In order to attenuate the highfrequency harmonics, additional resonant branch at the double of the switching frequency is added to the LLCL filter. The total inductance of this filter is almost less than the LLCL filter with the amount of the grid-side inductor. A comparative study on filter parameter design, size estimation, efficiency, stability, and dc-link dynamics in bidirectional power flow applications between the LLCL filter and the proposed L(LCL) 2 filter has been conducted. The assessment of these studies is presented through both experimental hardware implementation and MATLAB/Simulink-based simulation on a 700 W, 120 V/60 Hz single-phase grid-tied inverter. It is concluded that, compared with the LLCL filter, the L(LCL) 2 filter not only has less voltage drop and total component size, but also has better performance on reducing high-order current harmonics. Additionally, the L(LCL) 2 filter has a smaller size, less losses, stable closed-loop control system, and compared with traditional LLCL filter, it does not add any control difficulty to the system.

A New Topology of Higher Order Power Filter for Single-Phase Grid-Tied Voltage-Source Inverters

In order to reduce the influence of the grid harmonic currents and voltages, harmonic compensation is regularly implemented for a grid-tied inverter. In this study, a new topology of a higher order power filter for single-phase grid-tied voltage-source inverters, named L(LCL) $_{2}$ , is presented. The subscript is added to the name to prevent confusion with the LLCL filter. In the proposed design, the inverter side inductance is divided into three parts, and the grid side inductor is removed. Also, an additional resonant branch at the double of the switching frequency is added to the traditional LLCL filter to attenuate high-frequency harmonics. The overall inductance of the recommended filter is smaller than the LLCL filter. A comparative study and discussions on the subject of the traditional LLCL filter and the proposed L(LCL) $_{2}$ filter have been conducted and assessed through an experimental hardware implementation on a 700 W, 120 V/60 Hz single-phase grid-tied inverter. Furthermore, a straightforward engineering design benchmark is suggested to discover parameters of the L(LCL) $_{2}$ filter. Moreover, stability analysis, loss analysis and an optimization of the L(LCL) $_{2}$ filter parameters have been conducted in this study. The analysis shows that in comparison with the LLCL filter, the L(LCL) $_{2}$ filter not only has lower voltage drop and less total inductor size, but also has improved performance in decreasing high-order current harmonics.

An LLCL Power Filter for Single-Phase Grid-Tied Inverter

This paper presents a new topology of higher order power filter for grid-tied voltage-source inverters, named the LLCL filter, which inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency. Particularly, it can attenuate the switching-frequency current ripple components much better than an LCL filter, leading to a decrease in the total inductance and volume. Furthermore, by decreasing the inductance of a grid-side inductor, it raises the characteristic resonance frequency, which is beneficial to the inverter system control. The parameter design criteria of the proposed LLCL filter is also introduced. The comparative analysis and discussions regarding the traditional LCL filter and the proposed LLCL filter have been presented and evaluated through experiment on a 1.8-kW-single-phase grid-tied inverter prototype.

Reducing the current harmonics of a wind farm generation based on VSC-HVDC transmission line by shunt active power filters

Clean energy refers to forms of energy that do not produce hazardous emissions, do not harm human and ecosystem health and do not destroy the environment during extraction from the Earth. One of these clean energies is wind power. Energy generated from the power of wind uses a passive form of energy collection; the system works by the force of wind and does not need any added energy. Integration of massive amount of wind power is a major challenge to power industry. One of the big issues is how to collect the wind power and feed it into the AC grid. The HVDC technology based on voltage source converter (VSC), has recently been an area of growing interest to solve this issue. Although VSC-HVDC provides solution for the connection of wind farms to the grid, some problems occur in this method. One of them is current harmonics. This paper focuses on using shunt active power filter in order to mitigate the harmonic currents produced by HVDC converters.