PV Power Converter Coordination for Stable MPPT and PR Switching
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Solution Overview
Problem
The power supply system using photovoltaic modules faces instability and reduced control precision due to fluctuations in total output power and output voltage when switching between maximum power point tracking (MPPT) mode and power reserve (PR) mode.
Innovation Solution
A power conversion system with multiple power conversion units and a control unit that switches the operating mode of target power conversion units between MPPT and PR modes, while keeping coordinated power conversion units in a constant mode, to adjust operating powers and minimize total power and voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power conversion unit switches between PR mode and MPPT mode to update reference power, then the power supply system can adapt to dynamic power grid fluctuations and maintain power reserve capability, but the total output power and output voltage fluctuate, endangering stability and control precision
Solution Approach 1:
The patent divides the power conversion system into multiple independent power conversion units (at least two units). When one unit switches between PR and MPPT modes to update reference power, other units remain in their current modes, providing stable output power. This segmentation allows the system to maintain overall stability while enabling adaptive power reserve capability through selective mode switching of individual units.
2Measurement precision
If the power conversion unit switches between PR mode and MPPT mode to detect maximum power, then the reference power can be updated accurately, but the switching causes fluctuation of total output power and output voltage
Solution Approach 1:
The patent uses other power conversion units as intermediaries to maintain system stability during maximum power detection. When one unit switches to MPPT mode for accurate maximum power detection, the other units continue operating in their current modes, acting as stable intermediaries that compensate for the power fluctuations caused by mode switching, thereby reducing overall output voltage fluctuation.
3Productivity
If the power conversion unit operates in MPPT mode to track maximum power, then the power supply system operates at maximum power point, but the system cannot freely adjust power for supporting when the power grid is in dynamic fluctuation period
Solution Approach 1:
The patent implements dynamic operational mode switching for each power conversion unit. Units can dynamically switch between MPPT mode (for maximum power tracking and high productivity) and PR mode (for power reserve and flexible adjustment). This dynamic capability allows the system to optimize between power generation efficiency and power adjustment flexibility based on real-time grid conditions, enabling free power adjustment during dynamic fluctuation periods while maintaining high efficiency operation during stable periods.
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 solution effectively reduces fluctuations in total output power and output voltage, enhancing the stability and control precision of the power supply system, and also reduces mechanical and thermal stresses on devices.
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 which includes N power conversion units and a control unit. The control unit selects a target power conversion unit and a coordinated power conversion unit in a control periodicity, controls an operating mode of the target power conversion unit to be sequentially switched between a PR mode and a MPPT mode, and updates a reference power based on a maximum power obtained in the MPPT mode, for an operating power of the target power conversion unit 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 controls an operating power of the coordinated power conversion unit to be coordinately adjusted, for a total variation of operating powers of the N power conversion units to be less than a variation threshold.