High Performance Single-Phase Single-Stage Grid-Tied PV Current Source Inverter Using Cascaded Harmonic Compensators

Nahla E Zakzouk,Barry W Williams,Ahmed A Helal,Ahmed K Abdelsalam

doi:10.3390/en13020380

Abstract

In this paper, a single-phase single-stage photovoltaic (PV) grid-tied system is investigated. The conventional pulse width modulated (PWM) voltage source inverter (VSI) is replaced by a PWM current source inverter (CSI) for its voltage boosting capabilities, inherent short-circuit proof and higher reliability features. Modeling, design, and analysis of the considered CSI are presented altogether with enhanced proposed control loops aided with a modified PWM technique. DC-link even current harmonics are commonly reflected as low-order odd harmonics in the grid resulting in a poor quality grid current. In order to overcome the latter, a high performance proportional resonant controller, applied in the inverter inner grid current loop, is proposed using cascaded resonant control units tuned at low-order frequencies to eliminate injected grid current harmonics. Hence, with a less-bulky smoothing inductor at the CSI DC-side, grid power quality and system efficiency are simultaneously improved. Simulation and experimental results verify the proposed controller effectiveness.

Highlights

World’s increasing energy consumption, depleting fossil fuels, and environmental problems encourage the use of renewable energy resources recently
System performance was studied for current source inverter (CSI) DC-link inductor (Ldc ) = 150 mH when applying a conventional proportional resonant (PR) controller (CPRC) in the grid current loop
Ldc was reduced to 50 mH and the latter was repeated once when applying conventional PR controller and again when applying the proposed cascaded harmonic compensator (PCHC)

Summary

Introduction

World’s increasing energy consumption, depleting fossil fuels, and environmental problems encourage the use of renewable energy resources recently. A number of PV modules form a string, each having its own inverter, maximum power point tracking (MPPT) is separately achieved for each PV string This overcomes non flexibility, MPPT mismatch, and power losses caused by the old centralized inverter topology. The string topology still suffers limited modularity because the whole string is operated at a single maximum power point (MPP) The latter may cause PV modules’ mismatch due to manufacturing tolerances or non-optimal conditions such as partial shading [9].

Methods

Results

Discussion

Conclusion