Wind Turbine Shadow Control Using Dual Light Sensors
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Solution Overview
Problem
Wind turbines cast intermittent shadows that can be perceived as a nuisance, particularly for sensitive objects like houses, and existing shadow control systems either rely on direct-light measurements or require multiple light sensors, leading to inefficient shut-down and resume operations.
Innovation Solution
A shadow-control system for wind turbines using two light sensors oriented eastward and westward to measure direct and indirect light intensities, with a hysteresis in thresholds to manage shut-down and resume operations, and optional temperature compensation and de-icing features to improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light sensors are used to measure direct and indirect light intensities, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the light measurement function by using two light sensors positioned at different orientations (one facing the rotor, one facing away) to separately measure direct and indirect light intensities. This segmentation allows accurate differentiation between direct sunlight and diffuse sky radiation without requiring a single complex sensor
Solution Approach 2:
The patent introduces the rotor itself as an intermediary object to separate direct and indirect light. By measuring light intensity with sensors positioned to face toward and away from the rotor, the system uses the rotor's physical presence as a natural mediator to distinguish between direct sunlight (when rotor faces sensor) and indirect light (when rotor faces away)
2Object-affected harmful factors
If shadow control is implemented with immediate shut-down response, then shadow prevention effectiveness is improved, but operational reliability deteriorates due to frequent shut-downs
Solution Approach 1:
The patent implements periodic sampling of light intensity measurements at predetermined time intervals rather than continuous monitoring. This periodic action allows the system to track changes in light conditions over time and distinguish between temporary fluctuations and sustained shadow conditions, reducing unnecessary shut-downs while maintaining effective shadow control
Solution Approach 2:
The patent uses feedback from sequential light intensity measurements to determine when shut-down conditions are met. By comparing measurements taken at different time intervals, the system provides feedback about the persistence and severity of shadow conditions, enabling intelligent decision-making about when to shut down the turbine to balance shadow prevention with operational reliability
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 prevents intermittent shadows from being cast onto sensitive objects by accurately determining shadow conditions using direct and indirect light measurements, reducing frequent shut-downs and improving operational reliability through hysteresis and temperature compensation.
Implementation Method 1
a set of light sensors to provide measured direct- and indirect-light intensities for the purpose of comparison, the light sensors being able to measure the direct- light intensity when irradiated by the sun and the indirect-light intensity when not irradiated by the sun
Data Source
Figure 1
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Figure 5~6
AI summary
A rotor of a wind turbine (1) may cast an intermittent shadow (5) onto an object (7) in the vicinity of the turbine. A shadow-control system (18) stops the wind turbine, based on a shadow-related shut-down condition. The condition is based on a result of a comparison between a direct-light intensity and an indirect-light intensity being beyond a direct-to-indirect light threshold (T1 off). A set of light sensors (9E, 9W) measures the direct- and indirect-light intensities. A sensor measures the direct light intensity when irradiated by the sun, and the indirect-light intensity when not irradiated by the sun. The set of light sensors to provide the measured direct- and indirect-light intensities for the comparison consists of two sensors, an eastward-oriented sensor (9E) and a westward-oriented sensor (9W).