Dynamic Perturbation Step MPPT for Photovoltaic Arrays
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Solution Overview
Problem
Existing maximum power point tracking (MPPT) methods face contradictions between dynamic performance and static performance due to fixed perturbation steps in photovoltaic power generation systems, affecting the system's ability to efficiently adjust to changing environmental conditions.
Innovation Solution
A method and device that automatically adjust the perturbation voltage step based on the ratio of the P-U characteristic curve of the photovoltaic array, using gradient perturbation voltage steps to optimize the system's performance and improve tracking efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a larger perturbation step is used in P&O algorithm, then response speed to external condition changes is fast, but power fluctuation near MPP is large
Solution Approach 1:
The patent implements dynamic adjustment of the perturbation step size based on the operating point's distance from MPP. When far from MPP, a larger perturbation step is used to achieve fast response. When near MPP, the perturbation step is automatically reduced to minimize power fluctuation. This dynamic adaptation resolves the contradiction between response speed and power stability.
Solution Approach 2:
The patent changes the perturbation parameter (voltage step size) based on the P-U characteristic curve analysis. By monitoring the relationship between power and voltage changes, the system automatically adjusts the perturbation step size to optimize both tracking speed and stability near the maximum power point.
2Stability of the object's composition
If a smaller perturbation step is used in P&O algorithm, then power fluctuation near MPP is small, but response speed to external condition changes is slow
Solution Approach 1:
The system dynamically switches between small and large perturbation steps based on real-time operating conditions. When the system detects that the operating point is far from MPP, it automatically increases the perturbation step size to improve response speed. When near MPP, it reduces the step size to maintain low power fluctuation, thus resolving the contradiction.
Solution Approach 2:
The patent employs parameter change by adjusting the perturbation voltage step size according to the slope of the P-U curve. The system monitors power-voltage relationship and adapts the perturbation parameter to achieve optimal balance between response speed and stability under different operating conditions.
3Device complexity
If fixed perturbation step is used in MPPT, then control algorithm is simple, but system optimization efficiency is reduced
Solution Approach 1:
The patent implements parameter change by making the perturbation step size variable rather than fixed. The system automatically adjusts the perturbation voltage based on the P-U characteristic curve analysis, which significantly improves optimization efficiency while maintaining relatively simple control logic that can be implemented in existing MPPT controllers.
Data Source
AI summary
A maximum power point tracking method, device and a photovoltaic power generation system. The maximum power point tracking method involves sampling a present voltage and a present current of a photovoltaic array and obtaining a present power based on the present voltage and the present current. The maximum power point tracking using a difference between the present power and a power for a previous sampling time as a present perturbation power, and based on a ratio of the present perturbation power to a perturbation power for a previous sampling time obtain a gradient perturbation voltage step ratio. Further, the maximum power point tracking obtains a perturbation voltage step based on the gradient perturbation voltage step ratio and the voltage difference between the present voltage and the voltage for the previous sampling time, and control an output voltage based on the perturbation voltage step.