Buffered Differential Power Processing for Shaded PV Strings
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Solution Overview
Problem
Traditional solar installations face inefficiencies due to partial shading and mismatch issues, with existing solutions like bypass diodes and DC optimizers not optimally addressing power loss and requiring high efficiency or centralized control.
Innovation Solution
A differential power processing (DPP) system with extensively sized energy storage modules allows individual DPP units to operate independently, pushing or pulling power differentially to maximize utilization and maintain bus stability, eliminating the need for centralized control and enabling scalable, efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bypass diodes are used to handle partial shading, then current can bypass affected sections, but forward voltage drop of diode causes significant power loss
Solution Approach 1:
A DPP converter is introduced as an intermediary device between the PV array and the load/grid. This converter differentially processes power from each PV module, allowing it to extract maximum power from illuminated modules while bypassing or minimizing current through shaded modules without the fixed voltage drop penalty of diodes. The DPP converter acts as a smart mediator that dynamically adjusts power flow based on real-time module conditions.
Solution Approach 2:
The system changes the operating parameters of PV modules by using the DPP converter to independently control the voltage and current of each module. Instead of forcing all modules to operate at the same current (which limits the string to the lowest-producing module), the DPP converter allows each module to operate at its own optimal parameters, thereby maximizing total power extraction even when some modules are shaded.
2Loss of energy
If DC optimizers are used as intermediaries, then power conversion efficiency improves, but hardware complexity and control requirements increase
Solution Approach 1:
The PV array is segmented into individually controllable modules, with each module connected to its own DPP converter. This segmentation allows independent optimization of each module's power extraction without requiring complex centralized control. Each DPP unit is a simple, standardized module that can be independently designed, manufactured, and controlled, reducing overall system complexity despite the increased number of components.
3Productivity
If DPP systems are implemented with real-time control, then power extraction efficiency improves, but control complexity and communication requirements increase
Solution Approach 1:
Each DPP converter is equipped with its own controller that autonomously determines the optimal operating point for its connected PV module. The controllers operate independently without requiring real-time communication with each other or a central controller. Each unit performs self-service by locally sensing its module's conditions and adjusting its power conversion accordingly, thereby achieving high power extraction efficiency while minimizing control complexity and communication requirements.
Data Source
AI summary
An exemplary system and method are disclosed for power control of a set of power sources or loads employing a differential power processing (DPP) assembly having a set of DPP units coupled to an energy storage module in abus, in which the energy storage module is extensively sized to mitigate transient conditions propagated by the set of power sources or loads to provide an extended controllable time window for the individual DPP unit to reduce control requirements for the DPP units. The individual DPP unit in the assembly would push or pull, differentially, only power to the power source or load to minimize its respective operation while maximizing the utilization of the respective power source or maintaining stability of the bus for the loads.