Photovoltaic String Failure Diagnosis via Current-Voltage Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large-scale photovoltaic systems face challenges in accurately diagnosing failures among hundreds of thousands of modules due to high inspection costs and difficulties in distinguishing output drops caused by failures from environmental variations, with existing methods requiring costly installation of measurement and communication means for each module.
Innovation Solution
A failure diagnosis system that includes an array measurement apparatus, string current measurement apparatus, and a monitoring apparatus to estimate irradiation and operating temperature of photovoltaic strings, allowing for accurate diagnosis by comparing measured and estimated current values, thereby reducing the need for extensive installation and lowering costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If measurement means and communication means are provided for each photovoltaic module to automatically detect failures, then failure detection capability is improved, but installation costs and device complexity increase significantly
Solution Approach 1:
The patent merges the measurement functions into a centralized array measurement apparatus that measures the total output of the photovoltaic array, rather than requiring separate measurement means at each module. The monitoring apparatus integrates environmental data and current-voltage characteristics to diagnose individual module failures through mathematical analysis, eliminating the need for physical measurement devices at each module location.
Solution Approach 2:
The patent introduces current-voltage characteristic curves as an intermediary tool that links the measured array output to the diagnostic information of individual modules. By analyzing the relationship between current and voltage across the array and comparing it with expected characteristics under given environmental conditions, the system can identify failed modules without direct measurement at each module.
2Reliability
If measurement means and communication means are provided for each photovoltaic module to automatically detect failures, then failure detection capability is improved, but inspection costs increase
Solution Approach 1:
The patent combines multiple measurement and diagnostic functions into a single monitoring apparatus that processes array-level measurements and environmental data to diagnose individual module failures. This consolidation eliminates the need for expensive communication infrastructure and measurement devices at each module, significantly reducing inspection costs while maintaining failure detection capability.
Solution Approach 2:
The system uses freely available environmental data (irradiation, temperature) and standard array measurements to perform the diagnosis, rather than requiring specialized expensive equipment at each module. The monitoring apparatus self-calibrates using current-voltage characteristics and environmental conditions to identify failures without additional costly infrastructure.
3Measurement precision
If visual inspection, heat-generation inspection, or electrical characteristic inspection is conducted for each photovoltaic module, then failure detection accuracy is improved, but the efforts and costs required increase
Solution Approach 1:
The patent replaces manual visual inspections, heat-generation inspections with thermometers, and electrical characteristic inspections with testers by using an automated monitoring apparatus that performs mathematical analysis of current-voltage characteristics. This substitution eliminates the need for physical inspection efforts while maintaining diagnostic accuracy through computational methods.
Solution Approach 2:
The patent uses current-voltage characteristic curves as an intermediary that encapsulates the diagnostic information normally obtained through time-consuming physical inspections. By analyzing the relationship between array output current and voltage under measured environmental conditions, the system can identify failed modules without performing actual physical inspections at each module.
4Reliability
If output characteristics are monitored to detect failures, then failure detection is enabled, but it becomes difficult to distinguish failure-induced output drops from environmental condition effects
Solution Approach 1:
The patent changes the diagnostic approach from monitoring absolute output values to analyzing the relationship between current and voltage parameters under varying environmental conditions. By measuring both current and voltage and comparing their relationship against expected current-voltage characteristics for given irradiation and temperature levels, the system can distinguish between output changes caused by environmental factors and those caused by module failures.
Solution Approach 2:
The system uses environmental data (irradiation, temperature) as feedback to adjust the expected current-voltage characteristics for comparison with actual measurements. This feedback mechanism allows the monitoring apparatus to account for environmental variations and accurately identify deviations caused by module failures, maintaining diagnostic accuracy despite changing conditions.
Data Source
AI summary
A failure diagnosis system is configured to calculate an estimated irradiation on a first photovoltaic string and an estimated operating temperature of the first photovoltaic string based on a short-circuit current and an open-circuit voltage on a current-voltage characteristic of the first photovoltaic string, and the array output voltage value and the array output current value measured by an array measurement apparatus. The failure diagnosis system is configured to calculate an estimated current value of the first photovoltaic string based on the estimated irradiation, the estimated operating temperature, and the current-voltage characteristic. The failure diagnosis system is configured to diagnose degradation of the first photovoltaic string by comparing the measured current value of the first photovoltaic string and the estimated current value.