Arc Energy Evaluation in Photovoltaic Installations
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Solution Overview
Problem
Photovoltaic installations face challenges in detecting and managing electric arcs, which can lead to destructive energy release and potential fires due to the absence of natural arc quenching in DC systems, and existing detection methods can cause unwanted shutdowns or fail to accurately assess the energy generated by arcs.
Innovation Solution
A method and device that measure voltage and current signals across photovoltaic modules at high sampling frequencies to evaluate the energy produced by electric arcs, integrating voltage and current differences over time to determine arc energy, and compare it to a threshold for protective intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DC current and voltage are used in photovoltaic installations, then the system operates continuously without zero-crossing, but this causes electric arcs to generate large amounts of heat and energy for significant periods
Solution Approach 1:
The system performs preliminary detection of arc voltage and current parameters, then proactively integrates these measurements to calculate arc energy before the arc can generate excessive heat. This allows the system to intervene early with arc-quenching actions, preventing the harmful accumulation of arc energy that would otherwise occur in continuous DC operation
Solution Approach 2:
The system continuously monitors arc voltage and current, feeds this information back through integration to calculate real-time arc energy, and uses this feedback to control arc-quenching operations. This closed-loop feedback mechanism enables the system to maintain continuous productivity while dynamically managing and limiting harmful arc energy generation
2Reliability
If arc detection devices are installed to detect electric arcs, then arc presence can be identified, but this may cause unwanted shutdowns of the photovoltaic installation
Solution Approach 1:
The system changes the detection parameter from simple arc presence detection to arc energy evaluation by integrating voltage and current measurements over time. This parameter transformation allows the system to distinguish between harmful arcs requiring shutdown and benign arcs during normal operation, maintaining reliability while preventing unnecessary productivity loss
Solution Approach 2:
The system replaces the mechanical on/off shutdown response with a more sophisticated evaluation mechanism that integrates electrical parameters (voltage and current) over time to calculate arc energy. This substitution enables nuanced decision-making based on actual arc energy levels rather than binary detection, avoiding unwanted shutdowns while maintaining safety
3Measurement precision
If high sampling frequency voltage measurement is used to evaluate arc energy, then accurate arc energy assessment is achieved, but this increases measurement complexity and data processing requirements
Solution Approach 1:
The system merges voltage measurement and current measurement into a unified arc energy evaluation process through integration. By combining these measurements and processing them together through time integration, the system achieves precise arc energy assessment while reducing overall measurement system complexity compared to separate high-precision voltage and current measurement systems
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
Effectively assesses and manages electric arc energy in photovoltaic installations, preventing damage and fires by accurately measuring arc energy and triggering protective measures when thresholds are exceeded, while minimizing false shutdowns.
Implementation Method 1
measuring an electric voltage signal across the terminals of at least one photovoltaic module
Implementation Method 2
The plasma of the electric arc performs the role of a resistance that increases over time... releases a very large amount of heat for a significant period
Implementation Method 3
An electric arc is formed by a plasma that appears between two electrodes... The initial arc voltage Varc0 has a value that is characteristic of the appearance of an electric arc
Data Source
AI summary
The method comprises the steps of measuring (E0) a voltage signal at the terminals of at least one photovoltaic module of the installation (100) with a sampling frequency greater than or equal to 50 kHz and, from the measured voltage signal, determining an initial voltage preceding the appearance of the arc and voltage values during the electric arc; evaluating values of an electric current produced by the photovoltaic installation during the electric arc; time integration (E7) of the product of arc voltage values equal to the difference between the voltage values during the arc and the initial voltage, determined in step A), and current values evaluated in step B), in order to determine the energy of the arc.