Wind Turbine Parallel Converter Isolation via Transformer Windings
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Solution Overview
Problem
Wind turbine power converter systems experience common mode currents that circulate between parallel converter threads, 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 output power from parallel converter threads using sets of isolated power transformer windings, eliminating the need for common mode inductors and reducing harmonic components by configuring the converter system to prevent common mode current circulation between threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple parallel converters are used to increase power output capability, then power handling capacity is improved, but common mode currents circulate between converters causing overheating and distortion
Solution Approach 1:
A common mode inductor is introduced as an intermediary component in the neutral connection between parallel converters. This inductor acts as a mediator that blocks common mode currents from circulating between converters while allowing normal differential mode power transmission, thus resolving the harmful current circulation problem without sacrificing the power handling capability of the parallel converter configuration
Solution Approach 2:
The neutral connection between parallel converters is segmented by inserting a common mode inductor, which divides the continuous neutral path into isolated sections. This segmentation prevents the formation of closed loops that would allow common mode currents to circulate, while maintaining the electrical connection for normal power transmission through each converter thread
2Reliability
If large filters are used to smooth pulse width modulated waveforms, then power quality is improved, but system cost and complexity increase
Solution Approach 1:
The harmful common mode current component is extracted and blocked separately using a dedicated common mode inductor in the neutral line, while the main power transmission path continues with minimal filtering requirements. This extraction approach separates the common mode noise suppression function from the main power filtering, allowing for smaller, less expensive filters to handle only the necessary differential mode harmonics
Solution Approach 2:
The common mode inductor serves as an intermediary filtering element that specifically targets and suppresses common mode currents without requiring large bulk filters. This specialized intermediary component provides targeted power quality improvement for common mode interference while minimizing the overall filter size and system complexity
3Ease of operation
If converters are interconnected with common neutral points, then ease of connection is improved, but common mode currents are enabled to circulate
Solution Approach 1:
A common mode inductor is inserted as an intermediary element in the neutral connection between converters. This maintains the simple parallel interconnection topology with common neutral points for ease of wiring and operation, while the inductor mediator blocks the harmful common mode current circulation that would otherwise occur through the neutral path
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 solution effectively eliminates circulating common mode currents, enhancing system reliability, reducing costs, and minimizing the need for bulky filters, thereby improving the efficiency and cost-effectiveness of wind turbine power systems.
Implementation Method 1
supplying the power output of the power converter system to the load through at least one set of a plurality of isolated power transformer windings
Data Source
AI summary
A system and method are provided to isolate outputs of parallel converter threads of a power system converter of a wind turbine generator by utilizing isolated power windings on the output transformer from the converter. 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.