Wind Turbine Parallel Converters Isolated Generator Windings
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Solution Overview
Problem
Wind turbine power converter systems experience common mode currents that circulate between parallel converters, leading to overheating, distortion, and increased costs due to the need for large filters and inductors, which complicates fault detection and system reliability.
Innovation Solution
The method involves isolating the power windings of the generator to prevent common mode current circulation between parallel converter threads, eliminating the need for common mode inductors and reducing harmonic components by using isolated power windings configured in a wye or delta arrangement, thereby reducing system costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple parallel converters are used to increase power handling capability, then power output capability is improved, but common mode currents circulate between converters causing overheating and distortion
Solution Approach 1:
The generator is divided into multiple independent winding sets, with each winding set connected to a separate parallel converter. This segmentation electrically isolates the converters from each other, preventing common mode current circulation while maintaining individual power handling capability. Each converter thread processes power independently through its dedicated winding set.
Solution Approach 2:
The isolated generator windings act as an intermediary element between the generator and parallel converters. By introducing these isolated windings as a mediating component, the system achieves converter isolation without directly modifying the converter circuits themselves, thereby eliminating common mode currents while preserving system architecture.
2Reliability
If large filters and inductors are added to reduce harmonic components, then power quality is improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts and eliminates the need for large filters and inductors by addressing the root cause of harmonic generation. Through isolated winding connection, common mode currents that generate harmonics are prevented at the source, removing the requirement for bulky filtering components and reducing system complexity.
Solution Approach 2:
The system performs preliminary isolation of converter threads through dedicated generator windings before harmonics can generate and propagate. This preventive measure eliminates the need for corrective filtering actions, as common mode currents are blocked at their origin point in the generator windings.
3Reliability
If parallel converters operate without isolation, then system availability is improved, but fault detection becomes difficult due to circulating currents
Solution Approach 1:
By segmenting the electrical connection through isolated generator windings, each converter thread becomes electrically independent. This segmentation allows faults in one converter to be detected without interference from circulating common mode currents in other converters, significantly improving fault detection capability while maintaining system availability.
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 effectively eliminates common mode currents, enhancing system reliability, reducing costs, and minimizing the size of filters and inductors required, while maintaining power quality and reducing thermal stress on converter components.
Implementation Method 1
The spin of the blades caused by the wind spins a shaft of the rotor, which connects to a generator that generates electricity
Implementation Method 2
A converter system usually includes several power semiconductor switches such as insulated gate bipolar transistors (IGBTs), integrated gate commutated thyristors (IGCTs or GCTs), or metal oxide semiconductor field effect transistors (MOSFETs) that are switched at certain frequencies to generate the desired converter output voltage and frequency
Implementation Method 3
The power is transformed to appropriate voltage by one or more transformers 22 and supplied to the power grid 21
Data Source
AI summary
A system and method are provided to isolate outputs of parallel converter threads of a power system converter on a generator side of a wind turbine generator by utilizing isolated power windings on the wind turbine generator. Such isolation eliminates the circulating common mode current between the parallel converters of the wind turbine system and eliminates the need for a common mode inductor. System reliability is enhanced and total system cost is reduced.