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🌞 Different Types of P&O MPPT for PV Systems in MATLABVariable Step Size MPPT | Global Scan MPPT Explained

📌 Introduction

Maximum Power Point Tracking (MPPT) is a crucial technique for optimizing the performance of photovoltaic (PV) systems. Among several algorithms, Perturb and Observe (P&O) remains one of the most widely used due to its simplicity and adaptability.

In this guide, we’ll explore four P&O MPPT methods implemented in MATLAB/Simulink, compare their performance, and highlight why the Variable Step Size Global Scanning MPPT outperforms the rest.

🔹 1. Conventional P&O MPPT

⚙️ Working Principle

  • Uses PV voltage and current to calculate power.

  • Compares current and previous power values to adjust the boost converter duty cycle.

  • Decision logic:

    • If ΔP and ΔV have the same sign → decrease duty cycle (increase PV voltage).

    • If signs differ → increase duty cycle (decrease PV voltage).

📊 Limitation: Fixed step size causes slower convergence or oscillations near the MPP.

🔹 2. Variable Step Size P&O MPPT

⚙️ Improvements

  • Step size (ΔD) is not constant; it adapts based on operating conditions.

  • Calculates slope (ΔP/ΔV) to adjust step size dynamically.

  • Maintains faster tracking during large changes and reduces oscillations near MPP.

✅ Benefit: Better efficiency and quicker response under variable irradiance.

🔹 3. Improved Variable Step Size P&O MPPT

⚙️ Key Features

  • Introduces two adaptive step sizes: Step1 and Step2.

  • Additional decision parameter Δa determines which step size to use.

  • Provides finer control over adjustments, especially near the MPP.

✅ Benefit: Reduced overshoot and improved stability compared to single-step variable P&O.

🔹 4. Variable Step Size Global Scanning P&O MPPT

⚙️ How It Works

  • Combines variable step size tracking with global scanning capability.

  • Monitors difference between PV power and MPPT-estimated power.

  • If the difference > 15 W, the system resets tracking and scans for a new global MPP.

✅ Benefit: Handles partial shading and multiple MPP scenarios effectively.

📈 Performance Comparison

MPPT Method

Efficiency (%)

Max Power Tracking Ratio (%)

Output Power (W)

Conventional P&O

~97.8

~97.95

~242.3

Variable Step Size P&O

~98.9

~99.15

~246.0

Improved Variable Step Size P&O

~99.2

~99.38

~247.0

Variable Step Size Global Scanning P&O

99.5

99.68

248.1

🏆 Winner: Variable Step Size Global Scanning P&O MPPT delivers the best performance with minimal oscillations and near-perfect tracking efficiency.

🔍 Key Takeaways

  • Conventional P&O is simple but suffers from oscillations due to fixed step size.

  • Variable step size methods enhance tracking speed and stability.

  • Global scanning is essential for handling shading and multi-peak scenarios.

  • MATLAB/Simulink provides a robust environment to model, simulate, and compare MPPT strategies.

📢 Conclusion

If you’re developing a PV system in MATLAB/Simulink, Variable Step Size Global Scanning P&O MPPT is your best choice for high efficiency, stable performance, and adaptability to real-world conditions.

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