Photovoltaic Fault Detection via Normalized Voltage Deviation
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Solution Overview
Problem
Existing photovoltaic systems face challenges in reliably detecting faults, such as voltage reductions due to shading, dirty or broken solar cells, and high-impedance issues, which are often only recognized after several years, leading to inefficiencies and high maintenance costs.
Innovation Solution
A method and device that determine deviations in output voltage and derived parameters between two time points, comparing them to a predeterminable threshold to identify potential faults, allowing for real-time or offline monitoring without requiring system modifications, using measurements like maximum power point voltage and open circuit voltage, and optionally considering radiation and temperature factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If output voltage measurements are taken at different time points to detect faults, then fault detection capability is improved, but the complexity of comparing measurements under varying operating conditions worsens
Solution Approach 1:
The patent transforms the raw output voltage measurements into normalized values by dividing by the open-circuit voltage measurement. This parameter transformation eliminates the influence of varying operating conditions (radiation, temperature) and allows direct comparison of normalized values across different time points to detect faults
Solution Approach 2:
The open-circuit voltage measurement serves as an intermediary reference that mediates between the loaded and unloaded states. By using this intermediary, the patent creates a common basis for comparison that accounts for environmental variations without requiring complex multi-parameter measurements
2Measurement precision
If additional sensors are installed to monitor photovoltaic system parameters, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The photovoltaic system's own operational characteristics (open-circuit voltage and loaded voltage) are used as the measurement basis. The system essentially measures itself using existing electrical parameters, eliminating the need for external sensors while maintaining fault detection precision
Solution Approach 2:
The existing voltage measurement capability of the photovoltaic system is made multi-functional by using it for both normal operation monitoring and fault detection. The same measurement infrastructure serves dual purposes, avoiding additional sensor requirements
3Stability of the object's composition
If fault detection is delayed until several years of operation, then system stability is maintained, but productivity and energy efficiency deteriorate
Solution Approach 1:
The patent establishes a baseline normalized voltage value early in the system's operation and uses this preliminary reference to detect deviations throughout the system's lifetime. This preliminary action enables continuous monitoring without disrupting system stability, allowing early fault detection that maintains both stability and productivity
Data Source
AI summary
The invention relates to a method and a device for recognizing faults in a photovoltaic system (1). A first output voltage (U0, UMPP) of the system (1) and/or a first parameter derived from the output voltage (U0, UMPP) is determined at a first point in time in a first operating state of the photovoltaic system (1). At a second point in time in a second operating state comparable to the first operating state, a second output voltage (U0, UMPP) and/or a second parameter of the system (1) derived from the output voltage (U0, UMPP) is determined. Finally, a deviation between the first and the second output voltage (U0, UMPP) and/or between the first and the second parameter is identified and a fault notification is output if the deviation exceeds a predeterminable threshold.