Backup Box Switch Feedback for Safe PV Grid Isolation
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Solution Overview
Problem
Existing new energy power generation systems struggle to timely detect faults in backup boxes, leading to potential safety hazards due to uncontrolled power supply to the grid, which can endanger local loads and maintenance personnel.
Innovation Solution
A photovoltaic power supply system with a backup box that includes a grid-connected/off-grid switch and a potential detection mechanism, allowing the inverter to determine the backup box's status before supplying power to the grid, ensuring safe operation by detecting the switch's position using a potential detection point and communication circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the backup box is installed to control power circulation and isolation between the photovoltaic system, local load, and power grid, then fault isolation capability is improved, but the ability to detect backup box faults deteriorates
Solution Approach 1:
The patent implements a feedback mechanism by connecting an auxiliary contact to a potential detection point in the inverter. The auxiliary contact reflects the grid-connected/off-grid switch position, providing continuous feedback to the inverter about the backup box status. This enables the inverter to detect and respond to backup box states, resolving the detection difficulty while maintaining fault isolation capability.
Solution Approach 2:
The patent introduces an auxiliary contact as an intermediary element between the grid-connected/off-grid switch and the inverter. This auxiliary contact serves as a mediator that transmits switch position information to the inverter without interfering with the main power circulation control function of the backup box, thereby enabling detection while preserving fault isolation.
2Reliability
If the main contact controls power supply to the grid, then power isolation is improved, but the detection of switch position status deteriorates
Solution Approach 1:
The patent segments the switch contact into two separate functions: the main contact for power supply control and the auxiliary contact for status detection. This segmentation allows the main contact to focus on reliable power isolation while the auxiliary contact provides switch position information to the inverter, resolving the detection difficulty without compromising power isolation capability.
Solution Approach 2:
The auxiliary contact acts as an intermediary that transfers switch position information from the main contact mechanism to the inverter's detection circuit. This intermediary enables non-intrusive detection of switch status while the main contact maintains its primary function of power supply control and isolation.
Data Source
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AI summary
This application discloses a photovoltaic power supply system and a backup box. The photovoltaic power supply system includes a photovoltaic system and a backup box. A grid-connected/off-grid switch in the backup box includes a main contact and an auxiliary contact. The main contact and the auxiliary contact are linked, and the auxiliary contact operates in conjunction with a detection circuit in an inverter in the photovoltaic system, so that the inverter can detect a grid-connected/off state of the grid-connected/off-grid switch in the backup box before the backup box operates. Through a communication circuit in the backup box, the inverter and the backup box may further perform information transfer. These functions are implemented by an ingenious circuit design and a potential change at a potential detection point.