MATLAB Simulation of Solar PV Fed BLDC Motor Based Water Pump Under Partial Shading Conditions
System Overview
The system consists of two photovoltaic (PV) panels connected in series, with each panel generating around 1700 watts of power under standard test conditions. The panels are maintained at a constant temperature of 25°C, and their irradiation levels are varied to simulate both uniform and partial shading conditions. The solar energy from the panels powers a BLDC (Brushless DC) motor, which drives the water pump.
Simulation Setup
To begin, the simulation model includes the hybrid power system, using a combination of PO (Perturb and Observe), PSO (Particle Swarm Optimization), and BPT (Boost Converter) techniques to optimize power extraction. A boost converter (referred to as the Seta converter) is placed between the BLDC motor drive and the PV panels. The system's goal is to track the maximum power point of the solar panels efficiently under varying conditions.
The irradiation conditions for the two PV panels can be adjusted in the simulation to test different scenarios. In the first scenario, both panels receive uniform radiation, and the system aims to extract the maximum power using the hybrid PO PS1 BPT mode.
Testing Under Uniform Radiation Conditions
Under uniform irradiation, both solar panels receive the same level of radiation, and the system operates efficiently. The hybrid PO PS1 BPT method ensures that the system extracts the maximum power from the PV panels. As the system progresses, the power from the converter is adjusted, and the BLDC motor’s performance is measured, including parameters like speed, torque, and the back electromotive force (EMF).
After a short wait, the system reaches its maximum power point, and the inverter output stabilizes. During this process, the voltage and current from the converter are recorded, showing how the system adapts to maintain maximum power extraction.
Transition to PSO Mode
Next, the simulation switches to the PSO mode to observe the system’s performance when the power extraction algorithm changes. In PSO mode, the duty cycle is initially set randomly. As the system iterates, it adjusts the duty cycle to find the optimal point for power extraction. However, this process takes longer than the hybrid PO PS1 BPT method, as it may converge to a local maximum point rather than the global maximum. This is one of the challenges of using PSO for MPPT.
The system's power extraction fluctuates during the initial iterations, but eventually, it reaches a local maximum power point. This behavior illustrates the potential drawbacks of PSO when the system is under varying radiation conditions, particularly when it takes longer to find the optimal duty cycle.
Challenges with MPPT Algorithms
The PSO algorithm, while effective, presents challenges in real-world applications due to its slower convergence time and tendency to get stuck at local maxima. The PO algorithm also suffers from slower performance compared to the hybrid PO PS1 BPT method. These issues can affect the efficiency of the water pumping system, especially in scenarios with fluctuating radiation.
On the other hand, the hybrid PO PS1 BPT method minimizes these issues, ensuring that the system reaches the maximum power point more efficiently. By dynamically adjusting the duty cycle, the hybrid method ensures faster and more accurate power extraction, making it a better choice for applications where rapid response is critical.
Testing Under Partial Shading Conditions
One of the most critical scenarios for testing solar power systems is partial shading, which occurs when one of the panels receives less sunlight than the other. In this simulation, after one second, the irradiation of the first panel is reduced to 500W, creating a partial shading condition. The system then adapts to extract the maximum power from both panels.
Under partial shading conditions, the hybrid PO PS1 BPT method performs excellently, maintaining efficient power extraction even when one panel is shaded. The system is able to adjust the power extraction from each panel independently, ensuring that the water pump continues to operate effectively despite the shading.
Comparison of Hybrid PO PS1 BPT and PSO Under Partial Shading
In the final part of the simulation, we compare the performance of the hybrid PO PS1 BPT and PSO under partial shading conditions. The results show that the hybrid PO PS1 BPT method extracts the maximum power more efficiently than the PSO algorithm. In PSO mode, while the system eventually reaches a maximum power point, the power extraction process is slower and less stable compared to the hybrid method.
The hybrid PO PS1 BPT method ensures that the system quickly adapts to changing conditions and maintains optimal performance, making it ideal for applications like water pumping, where consistent and reliable operation is crucial.
Conclusion
The simulation of a solar PV-fed BLDC motor-based water pump under partial shading conditions demonstrates the importance of selecting the right MPPT algorithm for efficient power extraction. The hybrid PO PS1 BPT method outperforms the PSO algorithm in terms of speed and stability, particularly under partial shading conditions. By ensuring that the system can quickly adapt to changes in irradiation, the hybrid method provides a more reliable solution for solar-powered water pumping applications.
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