Active Filtering for Harmonic Mitigation in Multiphase Generators
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Solution Overview
Problem
Wind turbines face challenges in mitigating harmonic emissions, which can lead to mechanical vibrations, electrical power losses, and measurement errors due to the use of electronic power devices and electromechanical design imperfections, particularly in DC wind turbine power plants where extensive power conversion systems are required, affecting both harmonic currents and magnetic flux.
Innovation Solution
A multiphase generator-conversion system with m+1 electromagnetically coupled stators and active filtering converters that regulate current to mitigate harmonic content by directly controlling the magnetic flux of connected stators and indirectly affecting other stators through electromagnetic coupling, using a combination of diode rectifiers and active filtering converters in a shunt configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electronic power converters are used to obtain desired voltage waveforms, then power conversion capability is improved, but harmonic components are generated
Solution Approach 1:
The patent applies active filtering converters that generate compensating harmonic currents to cancel out the harmful harmonic components. The harmful harmonics generated by power converters are converted into beneficial cancellation signals through the active filtering mechanism, which injects opposite-phase harmonic currents to neutralize the distortion.
2Adaptability or versatility
If extensive power conversion systems are used in DC wind turbine power plants, then DC output capability is improved, but harmonic emission is increased
Solution Approach 1:
The active filtering converter acts as an intermediary between the power conversion system and the DC collection grid. It mediates the harmonic emissions by processing the power flow and filtering out harmonic components before they reach the DC grid, allowing DC output capability while reducing harmful emissions.
3Object-generated harmful factors
If active filtering converters are added to mitigate harmonics, then harmonic content is reduced, but device complexity is increased
Solution Approach 1:
The patent merges the active filtering converter with the existing power conversion system architecture. By integrating the filtering function into the converter structure and using shared components, the system reduces harmonic content while minimizing the increase in overall device complexity compared to separate filtering 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 reduces harmonic content in both connected and other stators, improving power quality, reducing mechanical stress, and minimizing electrical losses, while allowing for precise control of currents and efficient power extraction.
Implementation Method 1
At least one of the active filtering converters is arranged to directly control its current to vary or affect the magnetic flux of the stator to which it is connected
Implementation Method 2
indirectly modify or affect the magnetic flux of the rest of the stators through the electromagnetic coupling between them
Data Source
AI summary
Multiphase generator-conversion systems are disclosed. The system includes a multiphase generator having one rotor and m+1 number of electromagnetically coupled stators, each stator having a plurality of phase legs. The system includes a converter having m+1 conversion lines, each conversion line connected to the plurality of phase legs of one of the m+1 stators. Each conversion line has a rectification module. At most m of the m+1 rectification modules has an active filtering converter. At least one of the m+1 rectification modules has a passive rectifier. At least one of the active filtering converters is configured to directly control its current to vary the magnetic flux of the stator to which it is connected and indirectly affect the magnetic flux of the rest of the stators through the electromagnetic coupling. Also disclosed are wind turbines that include generation conversion systems and methods of mitigating harmonics in multi-phase generator-conversion systems.