Photovoltaic Fault Diagnosis Using Bidirectional Signal Reflection
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Solution Overview
Problem
Existing fault diagnosis methods for photovoltaic arrays require a normal photovoltaic string for comparison, which is difficult to prepare due to environmental influences, and struggle with high-resolution diagnosis of individual photovoltaic modules due to short signal transmission distances and non-uniform signal propagation speeds.
Innovation Solution
A fault diagnosis system that generates input signals at both the positive and negative terminals of a photovoltaic string or module, observes reflected waves, and estimates fault locations using reflection times and string lengths or module counts, without the need for a normal reference string, employing an attenuator and switching unit to control signal propagation and diagnose faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a normal photovoltaic string is used for comparison in fault diagnosis, then the fault location can be estimated, but the preparation becomes difficult due to environmental influences and installation variations
Solution Approach 1:
The system uses the photovoltaic string itself as the reference by comparing forward and reverse transmission signals. The normal string acts as its own benchmark, eliminating the need for a separate reference string and solving the preparation difficulty while maintaining diagnostic accuracy
Solution Approach 2:
The diagnosis method transmits signals in both forward and reverse directions through the same photovoltaic string. By comparing the transmission characteristics from both directions, the system can identify faults without requiring a separate normal reference string, as the inverse transmission provides the comparative baseline
2Measurement precision
If high-speed pulse generators and waveform observers are used to achieve high resolution in photovoltaic module diagnosis, then neighboring photovoltaic cells can be distinguished, but the system complexity and cost increase
Solution Approach 1:
The system changes the transmission distance parameter by using the entire photovoltaic string length as the transmission path. This extended distance naturally slows down the signal propagation and extends the observation time window, allowing standard-speed equipment to achieve high resolution without requiring extremely high-speed components
Solution Approach 2:
The diagnosis approach transitions from time-domain high-speed measurement to spatial-domain analysis by utilizing the physical length of the photovoltaic string. The fault location is determined by analyzing signal characteristics along the spatial dimension of the string rather than relying solely on temporal resolution
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
Enables accurate fault location diagnosis in photovoltaic strings and modules without a normal reference, reducing costs and simplifying field diagnostics, and achieves high-resolution fault identification without high-speed pulse generators or observers.
Implementation Method 1
observing a positive terminal output signal which is outputted from the positive terminal as a reflected wave of the positive terminal input signal and for observing a negative terminal output signal which is outputted from the negative terminal as a reflected wave of the negative terminal input signal
Data Source
AI summary
A fault diagnosis method utilizing a fault diagnosis system for diagnosing a photovoltaic module by estimating a fault location, the fault diagnosis system including a signal generator for generating and inputting an input signal into a positive terminal or a negative terminal of the photovoltaic module, a waveform observer for observing a reflected output signal from an open end or the fault location, a diagnosis unit for estimating the fault location based on the output signal, a conductive body, and an alignment unit for controlling the positions of the conductive body and/or the photovoltaic module. The diagnosis method includes controlling the positions of the conductive body and/or the photovoltaic module, observing the output signal of the input signal, and estimating the fault location based on two reflected output signals of input signals inputted into the positive terminal and the negative terminal of the photovoltaic module.