PV Shutdown Bypass Switching for Single-Device Fault Isolation
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Solution Overview
Problem
In photovoltaic power generation systems, the series connection of shutoff devices can lead to abnormal operation when one device fails, causing all photovoltaic module groups to stop outputting direct current power, which in turn prevents the inverter from integrating alternating current power into the grid, posing safety risks and operational inefficiencies.
Innovation Solution
A method and apparatus for controlling a shutoff device that includes N main switching transistors and N bypass switching transistors, where the bypass transistors are activated when the power supply voltage falls below a certain threshold, isolating faulty modules and allowing other groups to output direct current voltage to the inverter, ensuring normal system operation and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shutoff devices are connected in series to ensure safety when arc occurs, then safety protection is improved, but system reliability deteriorates because one failed device causes all photovoltaic module groups to stop outputting power
Solution Approach 1:
The patent divides each shutoff device into two independent circuits: a main circuit with main switching transistors for normal power transmission, and a bypass circuit with bypass switching transistors for fault isolation. This segmentation allows the system to maintain safety functions while preventing a single point of failure from affecting the entire series-connected system, as faulty modules can be isolated through the bypass circuit without stopping other photovoltaic module groups.
2Object-affected harmful factors
If shutoff devices are added to protect against arcs and ensure safety, then safety protection is improved, but device complexity increases due to multiple switching transistors and control circuits
Solution Approach 1:
The patent merges the safety protection function and the power transmission function into a single shutoff device structure. The main switching transistors handle normal power transmission while the bypass switching transistors provide arc protection and fault isolation. This merging eliminates the need for separate safety devices, reducing overall system complexity while maintaining comprehensive safety protection.
Solution Approach 2:
The shutoff device is designed with multi-functionality: the main switching transistors enable normal power transmission, the bypass switching transistors provide arc protection, and the same device structure enables fault isolation. This multi-functional design reduces the total number of components needed compared to having separate devices for each function, thereby reducing device complexity while improving safety.
3Reliability
If bypass switching transistors are activated to isolate faulty modules, then system reliability is improved by allowing other groups to continue operating, but device complexity increases due to additional switching components
Solution Approach 1:
The bypass switching transistors and bypass circuits are pre-configured within each shutoff device during system assembly. When a fault is detected, the control circuit can immediately activate the bypass switching transistors to isolate faulty modules without requiring additional components or complex real-time reconfiguration. This preliminary preparation reduces the complexity of fault handling while maintaining high system reliability.
Data Source
AI summary
A method and an apparatus for controlling a shutoff device, and a shutoff device. The shutoff device includes N main switching transistors and N bypass switching transistors. The method includes: controlling the N main switching transistors to be turned on after receiving a heartbeat signal; determining whether a power supply voltage of a processor is less than a first under-voltage protection voltage; and if so, controlling the N main switching transistors to be turned off, and controlling the N bypass switching transistors to be turned on. Thus, N photovoltaic modules and N main switching transistors corresponding to a shutoff device are separated from multiple photovoltaic module groups, so that the photovoltaic module groups corresponding to other shutoff devices can normally output DC voltage to an inverter, and the inverter can normally output AC power for integration into a power grid, thereby ensuring the normal operation of the photovoltaic system.