Step By Step Implementation of P&O MPPT In MATLAB
Introduction
Step-by-step implementation of Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) for a Solar PV system using MATLAB's Simulink. Here we will cover everything from creating the model to tuning the PI controller for optimal performance.
1. Creating the Model
To start, we'll open Simulink to create our model. The core components we'll be using are a Solar PV array and a boost converter. We'll first fix the solar PV array and then design the inductor (L) and capacitor (C) values for the boost converter. Following that, we will design the P&O MPPT for the Solar PV system and implement a PI controller to generate the duty cycle for the PWM generator. This PWM generator will produce pulses for the boost converter to extract maximum power from the PV array.
2. Configuring the Solar PV Array
We'll begin by setting up the PV array. For this example, we'll design the array to generate 3 megawatts of power. We choose the SunPower panel rating, which provides a maximum power rating of 445W, with a voltage at the maximum power point (MPP) of 76.7V. By using 5 panels in series, we achieve a terminal voltage of approximately 384V. To generate 3 megawatts, we calculate the number of parallel strings required.
3. Designing the Boost Converter
Next, we design the boost converter, which is crucial for stepping up the voltage from the PV array. We use the standard equations to calculate the inductance (L) and capacitance (C) values for the converter. For this design, the power is set to 3 megawatts, the panel voltage at MPP is 383.5V, and the switching frequency is 10 kHz. The output voltage is set to 600V. After calculating, we update the Simulink model with the appropriate L and C values, as well as the load resistance.
4. Implementing P&O MPPT
To implement the P&O MPPT, we use a combination of blocks in Simulink. We start by calculating the change in voltage and current using unit delay blocks. This helps us determine the change in power, which is crucial for the P&O algorithm. Based on the changes in power and voltage, we adjust the reference voltage using switches and constant blocks. The reference voltage is then combined with the PV panel voltage to calculate the duty cycle.
5. Tuning the PI Controller
The PI controller is essential for ensuring that the system operates efficiently at the maximum power point. Initially, we may observe oscillations in the PV voltage and current, indicating that the PI controller needs tuning. Using MATLAB's auto-tuning feature, we can identify the plant transfer function and adjust the PI parameters accordingly. This step is crucial for minimizing oscillations and achieving a stable maximum power output.
6. Testing and Validation
After tuning the PI controller, we simulate the model to verify the performance. The goal is to minimize oscillations in the PV voltage, current, and power, as well as in the load voltage, current, and power. We continue fine-tuning the parameters until we achieve a stable and efficient system response.
Conclusion
In this post, we demonstrated the step-by-step implementation of P&O MPPT for a Solar PV system using MATLAB Simulink. By carefully designing the PV array, boost converter, and tuning the PI controller, we can efficiently extract maximum power from the solar panels
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