MPPT Controller Using Thévenin Model for Solar Power Optimization
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Solution Overview
Problem
Existing methods for Maximum Power Point Tracking (MPPT) in photovoltaic systems are not suitable for varying insolation conditions, leading to inefficiencies in power generation, particularly when multiple peaks exist in the current-voltage characteristics of solar panels.
Innovation Solution
A method that detects predetermined conditions in the load power of an electrical power source, acquires electrical characteristics to determine a global maximum load power value, and processes it to find a more accurate local maximum load power value using a Thévenin equivalent circuit, with dynamic step size adjustments and interpolation/extrapolation to refine the maximum power point detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MPPT methods are used, then the system is simple to implement, but the accuracy of maximum power point detection deteriorates under varying insolation conditions with multiple peaks
Solution Approach 1:
The patent segments the maximum power point detection process into two distinct phases: global maximum search and local maximum refinement. The global search phase uses a wide voltage sweep to identify the approximate maximum power point, while the local refinement phase applies a Thévenin equivalent circuit model with iterative optimization to precisely locate the maximum power point. This segmentation allows the system to achieve high detection accuracy without requiring a single overly complex algorithm to handle all scenarios.
Solution Approach 2:
The patent performs preliminary action by conducting a global maximum search first to establish an initial estimate of the maximum power point location. This preliminary result serves as the starting point for the subsequent local refinement phase, which uses the Thévenin equivalent circuit model. By performing this preliminary global search, the system prepares the necessary information for the more precise local optimization, avoiding the need to start the refinement process from an arbitrary point.
2Measurement precision
If wide voltage sweeping is performed to find global maximum, then the search coverage is comprehensive, but the time required to determine maximum power point increases
Solution Approach 1:
The patent divides the voltage sweeping process into two segments: a global search phase that performs wide voltage sweeping to identify the approximate maximum power point region, and a local refinement phase that uses a Thévenin equivalent circuit model with iterative optimization around the identified region. This segmentation allows comprehensive search coverage in the global phase while significantly reducing the time required in the local phase, as the voltage range for refinement is much narrower than the global search range.
Solution Approach 2:
The global maximum search serves as a preliminary action that quickly identifies the approximate location of the maximum power point. This preliminary result narrows down the search space for the subsequent local refinement phase, meaning the time-consuming wide voltage sweep is performed only once to establish the starting point, after which the system converges rapidly to the precise maximum power point using the Thévenin model with smaller voltage steps.
3Measurement precision
If local maximum refinement is applied, then the maximum power point detection accuracy improves, but the computational complexity increases
Solution Approach 1:
The patent applies parameter changes by using the Thévenin equivalent circuit model, which represents the photovoltaic system with simplified parameters (open-circuit voltage, short-circuit current, and equivalent resistance). The local refinement process iteratively adjusts these parameters based on measured voltage and current values, solving the quadratic equation derived from the Thévenin model to find the maximum power point. This parameter-based approach achieves high detection accuracy with relatively simple computational operations compared to more complex optimization algorithms.
4Measurement precision
If multiple sweeping periods are used to acquire current-voltage characteristics, then the data accuracy improves, but the measurement time increases
Solution Approach 1:
The patent employs periodic action by performing multiple voltage sweeping cycles to acquire current-voltage characteristics. Each sweeping period collects data points that contribute to building an accurate representation of the photovoltaic system's electrical characteristics. The system performs these periodic sweeps, processes the accumulated data to identify the maximum power point, and can repeat the process as needed to track changes in insolation conditions, thereby achieving accurate measurements through repeated periodic measurements rather than relying on a single measurement.
Data Source
AI summary
A method for regulating an electrical power source, comprising the steps of detecting for one or more predetermined conditions associated with a load power of the electrical power source, whereupon the one or more predetermined conditions is detected, acquiring electrical characteristics of the electrical power source to determine a global maximum load power value arranged to approximate a true maximum load power of the electrical power source, and processing the global maximum load power value to determine a local maximum load power value of the electrical power source, wherein the local maximum load power value is arranged to be more accurate in approximating the true maximum load power of the electrical power source when compared with the global maximum load power value.