Power electronic controller with time sharing switching strategy for grid connected PV systems

Maria Jenisha Charles,Binu Ben Jose Dharmaianretnam,Ammasaigounden Nanjappagounder

doi:10.3906/elk-1804-47

Maria Jenisha Charles, Binu Ben Jose Dharmaianretnam + Show 1 more

Open Access

https://doi.org/10.3906/elk-1804-47

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Abstract

The design and implementation of a high-efficiency two-stage power electronic controller for feeding power from a photovoltaic (PV) array to the load/utility grid is proposed. The PV array is connected to the load/utility grid through a boost converter and an inverter. The boost converter is controlled by sinusoidal pulse width modulation (SPWM) pulses so as to get a clamped quasi-sinusoidal waveform at the DC link. The inverter converts the clamped quasi-DC voltage into AC voltage using the SPWM controller. At any time only one switch operates at high frequency, thus yielding reduction in the switching losses of the converters. The controller used for the inverter takes care of both the maximum power point tracking (MPPT) at unity power factor (UPF) and grid synchronization. The power electronic controller has been constructed using IGBT switches. The complete system has been modeled with MATLAB/Simulink software and simulation results are compared with experimental results. Experiments have been conducted at varying irradiations for both stand-alone (110 W) and grid-connected (110 V, 50 Hz) systems with a PV array of 130.2 V and 4.5 A employing the dSPACE DS1103 controller. The steady-state and dynamic responses of the proposed system are presented.

Highlights

Renewable energy sources such as solar, wind, and biomass are widely preferred for electrical power generation due to their limitless availability and ecofriendly nature
An efficient control scheme has been implemented for a PV system with an integrated two-stage power converter for feeding power to the load/grid
The sinusoidal pulse width modulation (SPWM) switching employed for the boost converter generates a clamped quasi-sinusoidal waveform at the DC link, which is converted to a pure sine wave by the voltage source inverter (VSI) with a smaller filter

Summary

Introduction

Renewable energy sources such as solar, wind, and biomass are widely preferred for electrical power generation due to their limitless availability and ecofriendly nature. The common constraint of such single-stage configurations is that the PV array voltage needs to always be higher than the peak value of the grid voltage To overcome this limitation, an improved single-stage topology was proposed. To handle a variable DC input voltage/PV source, Rong et al and Dipankar et al proposed a two-stage power conversion system using a high step-up converter (DC-DC) and conventional VSI [10, 11]. Some authors proposed two stages of power conversion using a cascaded buck-boost converter and conventional VSI for feeding the utility grid [12, 13]. Due to increased switching control complexity in the above scheme, [16] proposed a two-stage power conversion with a DC-DC converter and VSI using time sharing control. The SPWM-based controller of the VSI ensures that the maximum PV power available is supplied to the utility grid at unity power factor (UPF)

Proposed system

Time sharing operation of the proposed scheme

Grid-connected system

MPPT controller

Results with utility grid

Conclusion