Grid Interconnection Apparatus Fault Diagnosis
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Solution Overview
Problem
Current grid interconnection apparatuses face challenges in diagnosing faults, particularly when the cause is a transient issue like a lightning strike or instantaneous grid voltage distortion, leading to unnecessary user and manufacturer costs due to incorrect identification of the fault source.
Innovation Solution
A fault diagnosis method that involves stopping the interconnected operation, performing an independent power supply to a storage battery, measuring the output power state, and determining if it meets predetermined conditions to initiate an error process for user notification, allowing for automatic fault diagnosis even when the interconnected operation is stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the grid interconnection apparatus performs an error process immediately when detecting abnormality, then the response speed is improved, but the measurement precision of the fault diagnosis deteriorates
Solution Approach 1:
The patent applies preliminary action by performing an independent operation test before finalizing the fault diagnosis. When abnormality is detected during interconnected operation, the system first switches to independent operation mode to test whether the abnormality persists. Only if the abnormality continues in independent operation does the system execute the error process. This preliminary testing phase allows the system to distinguish between transient disturbances (like lightning strikes or grid voltage distortions) and actual equipment faults, thereby improving measurement precision without sacrificing response speed.
2Measurement precision
If the grid interconnection apparatus performs independent operation test, then the measurement precision of fault diagnosis is improved, but the loss of time increases
Solution Approach 1:
The patent applies periodic action by implementing a structured, time-limited test sequence. The independent operation test is performed as a periodic diagnostic cycle with specific duration and steps. The system switches to independent operation for a predetermined test period, monitors the output power state, and then automatically returns to interconnected operation if the test passes. This periodic approach ensures that the diagnosis process is systematic and time-bound, preventing excessive time loss while maintaining high measurement precision through thorough testing.
Data Source
AI summary
A fault diagnosis method of diagnosing a fault related to a PV PCS 150, configured to perform an interconnected operation in which a PV 100 is interconnected to a grid 10: supplies power from independent operation output of the PV PCS 150 to a storage PCS 250 by an independent operation that does not interconnect the PV 100 to the grid 10 after the grid interconnection apparatus stops the interconnected operation by detecting abnormality; measures an output power state of the PV 100 and/or the PV PCS 150 when power is supplied to the storage PCS 250; and determines that the fault occurs and performs an error process for notification to a user when the measured output power state does not satisfy a predetermined condition.