Power Converter Mode Switching for Stable MPPT and PR Control
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Solution Overview
Problem
The existing power conversion systems in power supply systems, particularly those using photovoltaic modules, face challenges in dynamically adjusting power output to match fluctuating grid conditions. This leads to instability and reduced control precision due to frequent switching between Maximum Power Point Tracking (MPPT) and Power Reserve (PR) modes.
Innovation Solution
A power conversion system comprising N power conversion units and a control unit, where the control unit periodically switches the operating mode of a target power conversion unit between MPPT and PR modes to accurately update the operating power. This approach reduces the fluctuation of output power and voltage by allowing only a part of the power conversion units to perform mode switching, while others remain in a constant mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power conversion unit switches between PR mode and MPPT mode to accurately track maximum power, then the control precision is improved, but the output power and voltage fluctuate, reducing system stability
Solution Approach 1:
The system divides N power conversion units into different groups, with only target units switching between PR and MPPT modes while other units remain in constant modes. This segmentation isolates the mode switching fluctuations to specific units, preventing system-wide power and voltage fluctuations while maintaining accurate maximum power tracking capability in the target units.
Solution Approach 2:
The control unit implements periodic mode switching for target power conversion units within control periodicity, alternating between PR mode and MPPT mode at predetermined intervals. This periodic action allows systematic updates of maximum power reference values while providing predictable, controlled fluctuations rather than random or continuous switching.
2Measurement precision
If all power conversion units switch between PR mode and MPPT mode to update operating power, then the control precision is improved, but the device complexity increases due to synchronized switching operations
Solution Approach 1:
The control system segments the N power conversion units into target units and other units, applying different control strategies to each segment. Only target units undergo mode switching operations, while other units maintain constant operating modes. This segmentation reduces the overall control complexity by limiting the number of units requiring dynamic mode management.
Solution Approach 2:
Instead of implementing mode switching in all power conversion units, the system applies partial action by selecting only specific target units for mode switching. This partial implementation achieves the necessary operating power updates without the excessive complexity of coordinating switching across all units simultaneously.
3Adaptability or versatility
If frequent mode switching is performed to track dynamic maximum power, then the adaptability to changing conditions is improved, but mechanical stress and thermal stress on devices increase
Solution Approach 1:
The system distributes the adaptive response burden across different unit groups. Only target units perform frequent mode switching to track dynamic maximum power changes, while other units operate in stable constant modes. This segmentation concentrates the adaptability requirement on specific units, reducing the cumulative mechanical and thermal stress on the entire system.
Solution Approach 2:
The control unit implements periodic mode switching for target power conversion units within control periodicity, alternating between PR mode and MPPT mode at predetermined intervals. This periodic action allows systematic updates of maximum power reference values while providing predictable, controlled fluctuations rather than random or continuous switching.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution effectively reduces the fluctuation of output power and voltage, enhancing the stability and control precision of the power supply system. Additionally, it minimizes mechanical and thermal stress on devices, leading to improved overall system stability.
Implementation Method 1
A power supply system is a new power generation system that uses photovoltaic effect of a photovoltaic module to convert solar radiation energy into electric energy
Data Source
AI summary
A power conversion system including N power conversion units and a control unit, which can control, in a control periodicity, operating modes of one or more target power conversion units in the N power conversion units to be switched between a PR mode and an MPPT mode, and update a reference power based on a maximum power obtained in the MPPT mode, for an operating power of the target power conversion unit obtained in the PR mode to be an updated reference power, and the updated reference power is less than or equal to the maximum power. In addition, the control unit further controls an operating mode of a power conversion unit other than the target power conversion unit in the N power conversion units to remain unchanged, so that the power conversion unit other than the target power conversion unit does not perform mode switching.