Parallel DC/DC Converter MPPT for PV String Voltage Drop
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Solution Overview
Problem
Existing PV installations face inefficiencies due to voltage drops at string terminals when DC/DC converters malfunction, leading to reduced power output and increased costs and complexity, especially when using high voltage systems or additional electrical installations.
Innovation Solution
A PV-optimiser power system employing a second DC/DC converter in parallel with the first, operating as an optimiser to execute a Maximum Power Point Tracking (MPPT) algorithm, avoids bypass diode conduction and maximizes energy extraction from PV panels, while ensuring the central inverter receives maximum power, with the second converter operating above the minimum starting load voltage of the first converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a DC/DC converter is connected in series to PV panels to feed auxiliary loads, then auxiliary power supply is enabled, but voltage drops occur at string terminals when the converter malfunctions, reducing power output
Solution Approach 1:
The patent divides the power conversion function into two separate parallel DC/DC converters instead of using a single series converter. This segmentation ensures that if one converter malfunctions, the other can continue operating without causing voltage drops that would reduce overall power output, thus resolving the contradiction between enabling auxiliary power supply and maintaining system reliability.
Solution Approach 2:
The patent implements a redundant DC/DC converter configuration where a second converter is prepared in parallel to compensate for potential failures of the first converter. This beforehand cushioning approach ensures that voltage drops are prevented even when malfunction occurs, maintaining both auxiliary power supply capability and system reliability.
2Power
If high voltage power supply from PV strings is used, then auxiliary power supply capability is improved, but system complexity and costs increase due to high voltage DC/DC converters
Solution Approach 1:
The patent merges the auxiliary power supply function with the existing PV string voltage by connecting DC/DC converters directly to the PV strings without requiring separate high voltage power supply systems. This integration approach enables auxiliary power supply while avoiding the additional complexity of high voltage DC/DC converters and separate electrical installations.
Solution Approach 2:
The DC/DC converters in the patent serve multiple functions: they enable auxiliary power supply, performs maximum power point tracking (MPPT) to maximize energy extraction from PV panels, and provide system protection. This multi-functionality reduces overall system complexity compared to dedicated high voltage power supply systems.
3Ease of operation
If additional electrical installations are added to power auxiliary systems, then auxiliary power supply is enabled, but costs increase
Solution Approach 1:
The patent implements a self-service approach where the PV installation itself provides power to auxiliary systems through DC/DC converters that extract power directly from the PV strings. This eliminates the need for separate electrical grid connections or additional power generation infrastructure, reducing both costs and material requirements while enabling auxiliary power supply.
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
This configuration enhances energy harvesting by preventing voltage drops and optimizing power output, maintaining system performance without affecting the central inverter or overall installation efficiency, and reduces costs by minimizing the need for additional electrical infrastructure.
Implementation Method 1
an auxiliary power supply device (D) disposed inside of the local zone and which provides local supply voltage to an auxiliary device (E), the auxiliary power supply device (D) being composed of a DC power converter (CP) electrically connected in series by respective input terminals (T1, T2) in the arrangement for generating direct current
Data Source
AI summary
A PV-optimiser power system for a photovoltaic installation for supply of power from a photovoltaic installation. The system includes a first DC/DC converter connected to a PV panel and to one or more energy storage modules, and a second DC/DC converter, connected in parallel to the PV panel in a string of PV panels of a PV installation, wherein the second DC/DC converter is configured to operate as an optimiser and execute a maximum power point tracking algorithm (MPPT) to determine the maximum power output of the PV panel of the plurality of the PV panels in the string.