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Fractional order PI controlled Grid Connected PV System

Fractional order PI controlled Grid Connected PV System

Introduction

Welcome to LMS Solutions! In this session, we will delve into the intricacies of a fractional order PI (Proportional-Integral) controlled connected PV system. Specifically, we'll compare it with a conventional PI controlled connected PV system. The primary focus will be on the utilization of a fractional order PI controller in the voltage control element block.



PV System Overview

Photovoltaic Panel Details

  • Single panel output: 13 watts

  • Maximum Power Point Voltage: 29 volts

  • Maximum Power Point Current: 7.35 amps

  • System Configuration: 10 series panels and 5 parallel strings

  • Maximum Power Output: 10.66 kilowatts at 1000 W/m²

Boost Converter and MPPT Algorithm

  • Voltage Boost: From 290 volts to 700 volts

  • MPPT Algorithm: BNBPD (Boost-Negative Boost Perturb and Observe)

Three-Phase Inverter and Control

  • Inverter Control: Feed-forward EQ control

  • DC Link Voltage: Controlled using Fractional PID Controller

  • PI Controller Parameters: ��=0.1,��=0.01,�=1.5,�=0.5Kp​=0.1,Kd​=0.01,λ=1.5,μ=0.5

Simulation and Results

Irradiation Conditions

  1. 400 W/m²

  2. 800 W/m²

  3. 600 W/m²

Fractional Order PI Controller Results

  • PV Power:

  • 400 W/m²: 4307 watts (Theoretical: 4313 watts)

  • 800 W/m²: 8589 watts (Theoretical: 8589 watts)

  • 600 W/m²: 6468 watts (Theoretical: 6475 watts)

  • Grid Current:

  • 400 W/m²: 10 amps peak

  • 800 W/m²: 16-17 amps peak

  • 600 W/m²: ~14-15 amps peak

  • THD of Grid Current:

  • <1%

Conventional PI Controller Results

  • PV Power:

  • 400 W/m²: 4292 watts (Theoretical: 4313 watts)

  • 800 W/m²: 8579 watts (Theoretical: 8589 watts)

  • 600 W/m²: 6463 watts (Theoretical: 6475 watts)

  • Grid Current:

  • 400 W/m²: ~10 amps peak

  • 800 W/m²: ~16-17 amps peak

  • 600 W/m²: ~14-15 amps peak

  • THD of Grid Current:

  • ~4% - 5%

Analysis and Conclusion

Comparing the two control strategies, the fractional order PI controller demonstrates superior performance in terms of PV power extraction and grid current quality. The THD of grid current is significantly lower with the fractional order controller, ensuring a more efficient and cleaner power transfer to the grid.

In conclusion, the fractional order PI controlled connected PV system outperforms the conventional PA controller in terms of power extraction and grid current quality. This innovative approach presents a promising avenue for enhancing the efficiency and reliability of grid-connected photovoltaic systems.


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