A Novel Strategy Based on Linear Active Disturbance Rejection Control for Harmonic Detection and Compensation in Low Voltage AC Microgrid

Hui Li,Junwei Lu,Chenmu Guo,Yue Qu,Shuang Li

doi:10.3390/en12203982

Abstract

In an AC microgrid, harmonic distortion is mainly caused by power electronic equipment and nonlinear loads. In this paper, linear active disturbance rejection control (LADRC) is used to control the fundamental current at the point of common coupling (PCC). Meanwhile, an active power filter (APF) is added to eliminate the harmonic current generated by the nonlinear loads. The tracking differentiator (TD) in active disturbance rejection control (ADRC) serves as a low-pass filter (LPF) in the harmonic detection algorithm of APF. Compared to traditional harmonic detection algorithms, the improved strategy solves the contradiction between rapidity, accuracy, and overshoot of filtering. LADRC has good performance of disturbance rejection, internal decoupling, and accessible parameters tuning. It can observe the internal uncertainty and external disturbance of the system as the total disturbance through the extended state observer (ESO), and compensate it in time through state feedback to make the system achieve the desired performance. The abilities of resonance suppression for LCL-type filter and internal decoupling of LADRC demonstrates its advantages through frequency domain analysis and simulation. The proposed strategy was simulated in MATLAB/SIMULINK and realized in the experimental hardware platform, and the effectiveness of the proposed strategy is approved.

Highlights

With the continuous improvement of semiconductor manufacturing technology, the performance of power electronic devices has been strengthened
According to the requirements of grid-connected current power quality, this paper proposes a strategy with grid-connected current control and harmonic suppression
We propose to use a nonlinear tracking differentiator (TD) instead of a low-pass filter to solve the contradiction between the response speed of the Butterworth filter and the filtering effect, so that the filtering is fast and no overshoot

Summary

Introduction

With the continuous improvement of semiconductor manufacturing technology, the performance of power electronic devices has been strengthened. The grid-connected inverter as an energy conversion interface plays a crucial role in delivering high-quality power into the grid. A single-function inverter cannot meet the needs of modern power equipment, and it is necessary to design a system that can control the current at point of common coupling (PCC). Single-function systems are slowly evolving toward large-scale composite systems [1]. The grid-connected inverter is the critical equipment for grid-connected power generation of renewable energy. Compared with the L-type filter, the LCL-type filter has higher frequency harmonic suppression capability and smaller inductance, which can reduce the physical size [2,3]

Results

Discussion

Conclusion