Wind Turbine Converter Thermal Protection for Grid Overcurrents
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Solution Overview
Problem
Existing protection strategies for wind turbine converters are inadequate in managing overcurrents caused by grid transients, particularly in DFIG configurations, leading to potential damage to semiconductor components and reduced wind turbine efficiency.
Innovation Solution
A method that estimates the junction temperature of semiconductor components in real-time by determining the current associated with power loss, estimating power loss based on current and component state, and using a thermal model to calculate the junction temperature, triggering a protection mechanism if the temperature exceeds a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If internal temperature sensors are used to monitor semiconductor component temperature, then temperature measurement is provided, but the response time is too slow to detect rapid temperature increases during hard transients
Solution Approach 1:
The patent replaces the physical temperature sensor measurement system with a computational model-based temperature estimation system. The thermal model calculates junction temperature in real-time by processing electrical parameters (power losses, thermal resistance, thermal capacitance) through mathematical relationships, eliminating the response time delay inherent in physical sensors while maintaining temperature monitoring capability.
2Measurement precision
If current sensors operate within their standard range to maintain measurement accuracy, then measurement precision is preserved, but they cannot measure the extremely high overcurrents that occur during grid transients
Solution Approach 1:
The patent applies partial action by using the current sensor only within its accurate measurement range for normal operation, and switching to a different measurement approach (voltage division method) when overcurrent conditions are detected. This allows the system to maintain measurement precision during normal conditions while gaining the ability to measure extreme currents during transients without compromising the sensor's primary function.
Solution Approach 2:
The patent introduces an intermediary measurement approach using voltage division across a known resistance to indirectly measure currents that exceed the current sensor's range. This intermediary method allows accurate determination of extreme currents during transients without requiring the current sensor to operate outside its designed measurement range.
3Productivity
If the converter handles higher currents to increase power output, then productivity increases, but the risk of semiconductor component damage from overcurrents increases
Solution Approach 1:
The patent implements preliminary protection action by continuously monitoring electrical parameters and using the thermal model to predict junction temperature before actual damage can occur. When the model predicts that temperature thresholds will be exceeded, the system preemptively triggers protection mechanisms (such as reducing power reference or isolating the converter) to prevent semiconductor component damage before it happens.
Solution Approach 2:
The patent establishes a feedback loop where the thermal model continuously estimates junction temperature based on real-time electrical parameters, and this temperature information feeds back to the control system to adjust operating conditions. This closed-loop feedback enables the system to maintain high power output while dynamically adjusting operation to prevent semiconductor overheating and damage.
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
This approach allows for real-time estimation and management of semiconductor component temperatures, effectively preventing damage from overcurrents and ensuring continued high output power from the wind turbine.
Implementation Method 1
estimating power loss associated with the one or more semiconductor components based on the determined current and on the state of the one or more semiconductor components
Implementation Method 2
using a thermal model of the one or more semiconductor components to estimate the junction temperature based on the estimated power loss
Data Source
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AI summary
A method of protecting a converter (110) of a wind turbine and a respective protection system are provided. The converter (110) is coupled to a generator (20) of the wind turbine to perform conversion of electrical power produced by the generator, the converter (110) comprising plural semiconductor components (150) that are operational to provide the conversion of the electrical power. The method includes the performing of a step of estimating a junction temperature (Tj) of at least one of said semiconductor components (150) by determining a current (I1, I2, I3) in the converter (110) associated with power loss in one or more of the semiconductor components (150); estimating power loss (PL) associated with the one or more semiconductor components (150) based on the determined current and on a state (sw) of the one or more semiconductor components; and using a thermal model (600, 700) of the one or more semiconductor components (150) to estimate the junction temperature (Tj) of at least one of the one or more semiconductor components (150) based on the estimated power loss (PL). The estimating step is repeatedly performed.