PV String Failure Detection via Current-Based Temperature Characteristic
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Solution Overview
Problem
Conventional PV inspection methods for mega solar systems are inefficient and costly, with high risks of switching errors and inaccurate failure detection due to temperature fluctuations, especially in large-scale systems where temperature differences can be masked within overall temperature distributions.
Innovation Solution
A PV inspection system that measures current output from multiple PV strings, calculates temperature characteristics based on these currents, and determines failure by comparing these characteristics, eliminating the need for manual switch operations and reducing the influence of temperature distributions, thereby improving detection accuracy and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measuring means and communicating means are provided for each PV module or string, then failure detection capability is improved, but system cost increases significantly
Solution Approach 1:
A single measuring means is designed to measure both voltage and current simultaneously, enabling multiple functions (voltage measurement, current measurement, and derived power/temperature characteristic calculation) with one device, thereby reducing the need for separate measuring instruments for each PV module or string
Solution Approach 2:
The system uses the measured voltage and current values to automatically calculate temperature characteristics and detect failures without requiring additional dedicated temperature sensors or manual inspection, allowing the electrical measurement system to serve multiple diagnostic purposes
2Device complexity
If manual connection switching of measuring means is performed sequentially, then cost is reduced, but inspection efficiency decreases and switching errors occur
Solution Approach 1:
The patent replaces manual mechanical switching operations with automatic electronic control. A control device automatically switches the connection between the measuring means and different PV modules or strings based on predetermined sequences, eliminating manual intervention and associated errors while improving inspection speed and consistency
Solution Approach 2:
A control device acts as an intermediary between the operator and the measuring means, managing the automatic switching sequence and coordination of measurements across multiple PV modules or strings, thereby eliminating the need for manual switching while maintaining system simplicity
3Ease of operation
If a fixed threshold is set for failure detection, then detection process is simplified, but detection accuracy decreases due to temperature and solar radiation fluctuations
Solution Approach 1:
The system dynamically adjusts the threshold for failure detection based on measured temperature characteristics and solar radiation conditions. Instead of using a fixed threshold, the threshold is modified according to environmental parameters that affect PV module performance, thereby maintaining detection simplicity while adapting to changing conditions to preserve accuracy
Solution Approach 2:
The system uses feedback from measured voltage, current, and temperature characteristics to automatically adjust detection thresholds. The control device continuously monitors environmental conditions and modifies the threshold accordingly, creating a closed-loop system that maintains high detection accuracy without requiring manual threshold adjustment
4Measurement precision
If infrared-ray imaging is used to detect high-temperature portions, then failure detection capability is improved, but system cost increases due to moving mechanism requirements
Solution Approach 1:
The patent replaces complex mechanical moving mechanisms with stationary electrical measurement systems. By measuring voltage and current and calculating temperature characteristics from these electrical parameters, the system achieves thermal detection capability without requiring physical movement or complex mechanical structures
Solution Approach 2:
The control device acts as an intermediary that translates electrical measurements (voltage and current) into temperature characteristic information, eliminating the need for direct thermal imaging hardware and complex moving mechanisms while still providing effective failure detection through electrical parameter analysis
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 detects local deteriorations in PV modules or strings by canceling out temperature distribution influences, enhancing detection accuracy while minimizing operational effort and costs, even in large-scale systems like mega solar systems.
Implementation Method 1
a monitoring unit which calculates a second temperature characteristic of the second PV string based on a value of the first output current and a value of the second output current
Data Source
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AI summary
A photovoltaic inspection system is provided, the photovoltaic inspection system detecting a failure by eliminating ON/OFF operation of a switch or others at the time of inspection or checkup as much as possible, reducing an influence of a temperature distribution as a whole with a small effort, and detecting a local deterioration in a photovoltaic module or string. According to a typical embodiment, in a photovoltaic system having a plurality of photovoltaic strings formed of one or a plurality of photovoltaic modules arranged to be aligned, a photovoltaic inspection system which detects the failure in the photovoltaic strings includes: a current detector which measures each of a first output current of a first photovoltaic string and a second output current of a second photovoltaic string; and a monitoring unit which calculates a second temperature property of the second photovoltaic string based on a value of the first output current and a value of the second output current and which determines whether the second photovoltaic string has the failure or not based on the second temperature property.