Arc Detection in Photovoltaic Installations via Dynamic Current Thresholds
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Solution Overview
Problem
Existing methods for detecting electric arcs in photovoltaic installations are either expensive due to the need for multiple voltage measurement sensors or lack reliability when using current sensors, particularly in AC-DC conversion systems where DC arcs do not self-quench and can cause destructive fires.
Innovation Solution
A method and device that measure electric current values from photovoltaic installations, adjust a variable current jump threshold based on measured values, and detect current jumps to identify electric arcs using a single sensor, incorporating algorithms to filter out noise and variations in current, thereby enhancing detection robustness and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage measurement sensors are installed across terminals of multiple photovoltaic modules to detect electric arcs, then detection coverage is improved, but device complexity and cost increase due to requiring multiple sensors
Solution Approach 1:
The patent combines multiple detection functions into a single current sensor placed at the inverter input. Instead of using multiple voltage sensors across different module terminals, the invention merges arc detection capability into the existing current measurement system, allowing one sensor to monitor the entire installation for electric arcs through current signature analysis
Solution Approach 2:
The current sensor performs dual functions: measuring operating current for power management and detecting electric arcs through current jump analysis. This multi-functional approach eliminates the need for separate voltage measurement sensors while maintaining comprehensive arc detection coverage across all modules
2Device complexity
If a single current sensor is used to detect electric arcs, then device complexity is reduced, but measurement precision deteriorates due to noise and current variations from illuminance and operating point changes
Solution Approach 1:
The patent implements a dynamic threshold that adapts to changing operating conditions. The threshold for detecting current jumps is not fixed but varies based on the measured current level, allowing the system to maintain detection sensitivity across different illuminance conditions and operating points while filtering out normal current variations
Solution Approach 2:
The invention changes the detection parameter from absolute current value to current jump magnitude relative to a dynamic threshold. By analyzing the rate of change and magnitude of current variations rather than fixed current levels, the system can distinguish arc-induced current jumps from normal operating fluctuations caused by illuminance changes
3Measurement precision
If voltage measurement is used to detect electric arcs, then measurement precision is improved for arc detection, but ease of operation worsens due to requiring multiple sensors and measurement points
Solution Approach 1:
The patent extracts the arc detection function from the voltage measurement domain and implements it in the current measurement domain. By analyzing current jumps instead of voltage edges, the system achieves arc detection using only the existing current sensor at the inverter input, eliminating the need for additional voltage sensors and simplifying installation and configuration
Data Source
AI summary
The photovoltaic installation being intended to supply an electric current (i), the method comprises the steps of measuring (e0) values representative of the electric current (i) supplied by the photovoltaic installation; adjusting (e2) a variable current jump threshold (s(ti)) according to measured values; detecting (e3) a current jump with an amplitude greater than a current jump threshold adjusted according to values measured before the jump; and detecting (e5) an electric arc based on the detection of a current jump.