Hybrid MPPT Control for PV Array Stability
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Solution Overview
Problem
In energy generating systems, particularly photovoltaic and wind energy systems, maximum power point tracking (MPPT) techniques fail to accurately determine optimal operating points under mismatched or partially shaded conditions, leading to reduced power production due to interactions between centralized and distributed MPPT controls, causing system oscillations and potential component damage.
Innovation Solution
Implementing a system that integrates local maximum power point tracking with centralized MPPT control, where each energy generating device is coupled with a local converter capable of reshaping voltage-to-current relationships, and a central MPPT control block that synchronizes and optimizes the operation of the entire array, preventing oscillations and ensuring maximum power production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If distributed MPPT control is implemented at the DC-DC converter stage, then each panel can operate at its maximum power point under mismatched or shaded conditions, but system oscillations occur and components may be damaged due to lack of synchronization with centralized MPPT control
Solution Approach 1:
The patent implements a feedback mechanism where the DC-DC converter's MPPT controller receives synchronization signals from the centralized MPPT controller at the DC-AC stage. This feedback loop ensures that local maximum power point tracking is coordinated with overall system operation, preventing oscillations and component damage while maintaining high power production efficiency.
Solution Approach 2:
The patent combines distributed MPPT control at the DC-DC converter stage with centralized MPPT control at the DC-AC stage into a unified hybrid system. This merging allows local panels to operate independently at their maximum power points while the centralized controller coordinates their collective operation, resolving the contradiction between individual panel optimization and overall system stability.
2Power
If DC-DC converters operate without synchronization to centralized MPPT control, then local power extraction is maximized, but string voltage grows indefinitely causing component damage
Solution Approach 1:
The patent introduces the centralized MPPT controller at the DC-AC stage as an intermediary that mediates between local DC-DC converters and the grid. This intermediary coordinates voltage levels and power flow, allowing maximum local power extraction while preventing uncontrolled voltage growth through synchronized control signals.
Solution Approach 2:
The patent implements preliminary synchronization actions where the centralized MPPT controller establishes coordination protocols before DC-DC converters begin operation. This preliminary setup ensures that local power extraction is maximized from the start while voltage growth is prevented through pre-configured control mechanisms.
3Device complexity
If only centralized MPPT control is implemented, then system complexity is reduced, but power production drops under mismatched or shaded conditions
Solution Approach 1:
The patent segments the MPPT control function into two levels: centralized control at the DC-AC stage for overall system coordination, and distributed control at each DC-DC converter for local panel optimization. This segmentation allows the system to maintain reduced complexity through modular design while achieving high power production under mismatched or shaded conditions through local intelligence.
Data Source
AI summary
A system for integrating local maximum power point tracking (MPPT) into an energy generating system having centralized MPPT is provided. The system includes a system control loop and a plurality of local control loops. The system control loop comprises a system operating frequency, and each local control loop comprises a corresponding local operating frequency. Each of the local operating frequencies is spaced apart from the system operating frequency by at least a predefined distance. For a particular embodiment, a settling time corresponding to the local operating frequency of each local control loop is at least five times faster than a time constant corresponding to the system operating frequency.