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Grid Connected PV System With SEPIC Converter in MATLAB

Grid Connected PV System With SEPIC Converter in MATLAB

Introduction:

Welcome to LMS Solution! In this tutorial, we'll explore a grid-connected photovoltaic (PV) system integrated with a SEPIC converter and an incremental conductance Maximum Power Point Tracking (MPPT) algorithm. This system is designed to generate approximately 100 kilowatts of power.


PV Panel Characteristics:

The PV panel in this system consists of 10 series-connected modules with 7 parallel strings, resulting in a single module power of 213.15 Watts. The open-circuit voltage is 36.3 volts, the maximum power point voltage is 29 volts, and the short-circuit current is 7.84 amps.

PV and IV Characteristics with Irradiation Variations:

For different irradiation conditions (1000, 500, and 100 watts per meter square), the corresponding PV and IV characteristics are considered. The system's response to varying irradiation levels is crucial for understanding its performance.

SEPIC Converter Design:

The SEPIC converter is designed based on the power rating of the PV array (100.2 kilowatts), with an input voltage of 290 volts and an output voltage of 600 volts. Parameters such as inductors (L1, L2) and capacitors (C1, C2) are designed accordingly.

Incremental Conductance MPPT Algorithm:

The MPPT algorithm involves measuring PV voltage and current. The incremental conductance (dP/dV) is calculated, and based on certain conditions, the duty cycle of the SEPIC converter is adjusted to extract maximum power from the PV panel.

  1. If ∣m∣<0.05, maintain the previous duty cycle.

  2. If ∣m∣≥0.05 and ΔV=0 and ΔI=0, maintain the previous duty cycle.

  3. If ΔI0, decrement the duty cycle.

  4. If ΔV0, check incremental conductance. Adjust duty cycle accordingly.

  5. Ensure duty cycle stays within maximum and minimum limits.

Grid Connection and Inverter Control:

The SEPIC converter's output is connected to a voltage source inverter (VSI), which is linked to the grid. The inverter is controlled using a feed-forward decoupling concept. The inverter current (ID and IQ) is controlled based on the reference values obtained from the voltage controller.

Simulation Results:

Simulations are conducted with varying irradiation conditions to observe the system's response. Power, voltage, and current profiles are analyzed at different time intervals.

  1. At 1000 watts per meter square, the system generates around 100 kilowatts.

  2. Irradiation changes to 800 and then 500 watts per meter square, affecting the power output.

  3. The system adjusts to irradiation changes, demonstrating effective MPPT and grid power injection.

Conclusion:

This tutorial provides a comprehensive overview of a grid-connected PV system with a SEPIC converter and an incremental conductance MPPT algorithm. By simulating different irradiation scenarios, we observe the system's ability to adapt and maximize power generation.

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