PV Inverter Arc Detection Using DC/DC Voltage Verification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for detecting arcing in photovoltaic systems can misdiagnose a failure to supply current as an arc fault due to changes in sunlight and interference from adaptive optimizers and rapid shutdown devices, leading to inaccurate fault detection.
Innovation Solution
A method involving stopping the control signal to a suspected DC/DC conversion circuit, decreasing voltage at its power supply side after a preset time, and restoring it if current exceeds a preset threshold, thereby distinguishing between false and real arcs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all DC/DC conversion circuits are turned off when a suspected electric arc is detected, then arc fault detection sensitivity is improved, but false diagnosis rate increases due to misinterpreting current supply failure as arc fault
Solution Approach 1:
The patent applies preliminary action by performing a verification test before finalizing the arc fault diagnosis. When current decreases to OA indicating suspected arc, the system first restores voltage and checks whether current recovers. This preliminary verification action distinguishes between true arc faults (where current remains at OA) and false faults caused by other factors (where current recovers), thereby reducing false diagnosis rate while maintaining detection sensitivity
Solution Approach 2:
The patent implements feedback by monitoring the recovery of current after voltage restoration. The system observes whether the photovoltaic string resumes current supply after the inverter is restarted, using this feedback information to confirm or refute the arc fault diagnosis. This feedback mechanism provides a verification step that prevents false diagnoses while maintaining accurate detection of real arc faults
2Speed
If the inverter is rapidly started to output voltage after turning off, then system response speed is improved, but misdiagnosis of arc fault occurs when photovoltaic strings fail to supply current due to external factors
Solution Approach 1:
The patent applies preliminary action by implementing a verification step between the shutdown and rapid start operations. After turning off the inverter upon detecting suspected arc, the system waits for a preset period, then restores voltage and monitors current recovery before finalizing the arc fault diagnosis. This preliminary verification prevents misdiagnosis while maintaining rapid response capability
Solution Approach 2:
The patent implements beforehand cushioning by introducing a preset time delay and verification process before the rapid start operation. This cushioning measure prevents hasty decisions that could lead to misdiagnosis, allowing the system to verify whether current supply failure is due to arc or other factors before committing to the rapid start and arc fault confirmation
Data Source
AI summary
A method for detecting arcing, an inverter and a photovoltaic system are provided. The inverter includes an inverter circuit and at least one DC/DC conversion circuit. The method includes: stopping outputting a control signal to a first DC/DC conversion circuit that is currently being suspected of having an electric arc, and operating other DC/DC conversion circuits connected to the inverter circuit normally; decreasing a voltage at a power supply side of the first DC/DC conversion circuit immediately after a first preset period of time elapsed; and determining that no arc fault occurs, and restoring the voltage at the power supply side of the first DC/DC conversion circuit to a first voltage that the first DC/DC conversion circuit receives before the stopping outputting the control signal, if a current at the power supply side is greater than or equal to a first preset current during the decreasing the voltage.