PV Combiner Box Protection Switch for Fast Short-Circuit Isolation
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Solution Overview
Problem
Existing photovoltaic power generation systems face challenges in effectively protecting photovoltaic units and lines from short-circuit faults due to high fusing currents and long fuse blowing times, which can lead to damage and increased cable costs.
Innovation Solution
The implementation of a photovoltaic power generation system that includes a protection switch with a release device and a switching device connected in series, which disconnects the interface from the direct current bus when a short-circuit fault occurs, preventing current flow to the faulty unit and eliminating the need for fuses, thereby reducing cable costs and implementation complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is connected in series to protect the photovoltaic unit and line, then the photovoltaic unit and line are protected from short-circuit faults, but the fusing current is relatively high and the fuse blowing time is long, reducing protection effectiveness
Solution Approach 1:
The patent replaces the mechanical fuse system with an electronic protection switch system that includes a control circuit. The control circuit detects short-circuit faults and triggers the protection switch to disconnect the faulty photovoltaic unit, replacing the slow mechanical fuse blowing process with fast electronic detection and switching, thereby significantly reducing the protection time and improving protection effectiveness.
2Productivity
If multiple photovoltaic units are connected to improve power generation efficiency, then the power generation efficiency is improved, but the short-circuit current becomes relatively large when a short circuit occurs, making it difficult for the fuse to blow effectively
Solution Approach 1:
The patent divides the photovoltaic system into independently protected units by connecting each photovoltaic unit through its own protection switch to the direct current bus. This segmentation allows the protection system to isolate and disconnect only the faulty unit while keeping other units operational, maintaining high power generation efficiency while ensuring reliable protection for each unit individually.
3Reliability
If a fuse is used for protection, then the photovoltaic unit and line are protected, but additional control circuits and fuse components are required, increasing system complexity and cable costs
Solution Approach 1:
The patent merges the protection function directly into the connection interface between the photovoltaic unit and the direct current bus by integrating the protection switch at this critical point. This integration eliminates the need for separate fuse components and their associated wiring (Y wire harness), reducing system complexity and cable costs while maintaining comprehensive protection capability.
Data Source
AI summary
A photovoltaic power generation system includes a protection switch and a plurality of DC-DC converters. Each DC-DC converter includes a direct current bus, a DC-DC circuit, and at least one input interface. The input interface is configured to connect to a photovoltaic unit. The photovoltaic unit includes at least one photovoltaic module. The input interface is connected to the direct current bus by using the protection switch, the direct current bus is connected to an input end of the DC-DC circuit, and an output end of the DC-DC circuit is an output end of the DC-DC converter. The protection switch includes a release device and a switching device that are connected in series. The release device is configured to: when a short-circuit fault occurs on a line in which the release device is located, control the switching device to be disconnected.