PV Shutdown Control for Inverter Overvoltage Without Power Loss
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Solution Overview
Problem
Photovoltaic power generation systems face issues where high input voltages can damage inverters, leading to system shutdowns and power loss, despite existing shutdown devices that prevent excessive voltages by cutting off input, thereby halting power generation.
Innovation Solution
A photovoltaic power generation system and method that utilizes shutdown apparatuses, including optimizers and shutdown devices, to dynamically adjust input voltages by turning off or adjusting output voltages based on preset conditions, ensuring the inverter operates within safe voltage limits while maintaining power generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shutdown devices are configured for each PV module to cut off input voltage when excessively high, then inverter safety is improved, but power generation is halted causing energy loss
Solution Approach 1:
The system divides the PV array into multiple strings with multiple modules per string, and configures shutdown devices at the string level rather than module level. When overvoltage occurs, only specific strings are disconnected while other strings continue to generate power, segmenting the impact and maintaining partial power generation capability.
Solution Approach 2:
Instead of disconnecting all PV modules when overvoltage occurs, the system selectively disconnects only the necessary portion (specific strings exceeding voltage thresholds) while allowing other strings to continue operating. This partial action maintains power generation from healthy strings while protecting the inverter from damaged strings.
2Power
If PV strings are connected in series to increase output voltage, then power transmission capability is improved, but inverter damage risk increases due to excessively high voltage
Solution Approach 1:
The system dynamically adjusts the number of series-connected strings based on real-time voltage monitoring. When overvoltage conditions are detected, the shutdown devices dynamically reconfigure the system by disconnecting specific strings, thereby dynamically adjusting the total output voltage to remain within safe operating limits while maximizing power transmission capability under normal conditions.
Solution Approach 2:
The system implements continuous voltage monitoring of each PV string with feedback control. When the monitored voltage exceeds preset thresholds, the control system triggers shutdown devices to disconnect the affected strings, reducing the total voltage back to safe levels. This feedback mechanism prevents inverter damage while maintaining optimal power transmission.
3Reliability
If shutdown devices are configured to cut off all input voltage when protection is triggered, then inverter protection is ensured, but the system cannot continue power generation causing operational loss
Solution Approach 1:
The system segments the PV array into multiple independent strings, each with its own shutdown device. When overvoltage occurs in specific strings, only those strings are disconnected while other strings continue to operate and supply power to the inverter. This segmentation allows the system to maintain productivity by utilizing healthy strings even when protection is triggered in affected strings.
Solution Approach 2:
The shutdown action is applied partially rather than globally. Instead of cutting off all input voltage when any overvoltage condition occurs, the system selectively applies shutdown only to the specific strings exceeding voltage thresholds. This partial shutdown action protects the inverter from damaged strings while maintaining power generation continuity through operational strings.
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
The system effectively manages input voltages to prevent inverter damage and ensure continuous power generation by using optimizers and shutdown devices to lower voltages when necessary, maintaining stable operation.
Implementation Method 1
solar energy is generally converted into electric energy by using a photovoltaic (PV) module
Data Source
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AI summary
This application discloses a photovoltaic power generation system and method, and the system includes an inverter and at least one shutdown apparatus. A type of the shutdown apparatus includes at least one of a shutdown device and an optimizer; and an input end of each shutdown apparatus is connected to a corresponding PV module, and power of the corresponding PV module is output. There are two cases based on whether all PV modules are configured with shutdown apparatuses. A first case is that an output end of each PV module is configured with the shutdown apparatus, and a second case is that output ends of some PV modules are not configured with the shutdown apparatuses. In the system, when a parameter of the inverter meets a preset condition, some shutdown apparatuses are turned off to lower an input voltage of the inverter, so as to ensure that an input voltage of the inverter does not exceed a safe voltage, and ensure that an input end of the inverter has a direct current source, and the system can operate as usual; and the preset condition is that the input voltage of the inverter is greater than a first preset voltage, or an input current of the inverter is less than a first preset current.