Solar String Shut-Off Circuit for Stable Low-Power Isolation
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Solution Overview
Problem
The installation cost of shut-off devices in solar power generation systems is high, and the stability of these systems is compromised due to the reliance on switching devices that can become unstable when power generation drops.
Innovation Solution
A solar power generation system is designed with a master-slave relationship between first and second shut-off devices, where the second shut-off device receives power from the first and cuts off connections in response to control signals, simplifying its configuration and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shut-off device is installed for each solar cell module to improve firefighter safety, then the safety of firefighters is improved, but the installation cost of shut-off devices increases
Solution Approach 1:
The solar cell modules are divided into multiple groups, and shut-off devices are installed at the group level rather than at each individual module. This segmentation approach maintains safety by ensuring that shut-off functionality is provided for each group while reducing the total number of shut-off devices required, thereby lowering installation costs.
Solution Approach 2:
A power supply unit is introduced as an intermediary component that provides power to the shut-off device. This power supply unit is connected in parallel to a group of solar cell modules and enables the shut-off device to operate independently of the inverter system, ensuring reliable operation during emergencies while reducing system complexity.
2Extent of automation
If the power generated by solar cell modules is used to drive the switching device, then the system can operate autonomously, but the switching device becomes unstable when power generation drops
Solution Approach 1:
A power supply unit is installed in advance to provide stable power to the shut-off device. This power supply unit is connected in parallel to the solar cell modules and contains a capacitor that stores energy, ensuring that the shut-off device maintains stable operation even when the power generation from solar cell modules drops or becomes unstable.
Solution Approach 2:
The power supply unit acts as an intermediary between the solar cell modules and the shut-off device. It decouples the power supply for the shut-off device from the main power generation system, providing a dedicated and stable power source that prevents switching device instability during low power generation conditions.
Data Source
AI summary
A solar power generation system includes a string, an inverter, a first shut-off device, and a second shut-off device. The string includes a plurality of solar cell module groups. The first shut-off device is connected to a first electric path. The second shut-off device is connected to a second electric path. The first shut-off device cuts off the connection between a plurality of solar cell module groups connected to the first electric path in response to a first control signal. The second shut-off device is driven by the power supplied from the first shut-off device, and cuts off the connection between a plurality of the solar cell module groups connected to the second electric path in response to a second control signal. The first shut-off device includes a first semiconductor switching device and a first open-close unit connected in series to the first semiconductor switching device.