Wind Turbine Transformer Stray Field Cross-Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-performance wind turbines require improved short-circuit behavior to maintain short-circuit current in relation to the mains, but existing systems with two parallel transformers are expensive and inefficient, leading to potential overloading of circuit breakers.
Innovation Solution
A system transformer with four windings arranged in two pairs, where each pair is separated and forms a magnetic cross-coupling via the stray field, providing two parallel and two crossing power flow paths, with the crossing paths having significantly higher impedance, allowing normal operation without interference and reducing short-circuit current impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two parallel transformers are connected to increase power transmission and limit short-circuit current, then the short-circuit current is limited, but the production costs and installation space increase significantly
Solution Approach 1:
The single transformer is segmented into two separate winding pairs (first pair and second pair), each capable of handling power independently. This segmentation allows the transformer to function similarly to two parallel transformers for short-circuit current limitation, while physically remaining as a single integrated unit, thus reducing costs and installation space.
Solution Approach 2:
The second pair of windings is nested within the stray field of the first pair of windings, and vice versa. This nested arrangement creates magnetic cross-coupling between the pairs, enabling both pairs to contribute to power transmission and short-circuit current limitation simultaneously within a single transformer structure.
2Reliability
If two parallel transformers are connected to improve short-circuit behavior, then the short-circuit current is controlled, but the installation space and production costs increase
Solution Approach 1:
Two separate transformers are merged into a single integrated transformer by providing two winding pairs within one transformer core structure. The windings are magnetically coupled through the core, combining the functions of two transformers into one unit, thereby reducing installation space and production costs while maintaining the short-circuit current limitation capability.
3Device complexity
If conventional two-winding transformer is used, then the design is simple and cost-effective, but the circuit breakers are overloaded during short circuits
Solution Approach 1:
The single winding pair is segmented into two separate winding pairs, each capable of independently handling power transmission. During a short circuit in one pair, the other pair remains operational and can share the load through magnetic coupling, preventing circuit breaker overloading while maintaining a relatively simple transformer design.
Solution Approach 2:
The transformer is designed with redundant winding pairs that are magnetically coupled but electrically independent during normal operation. In the event of a short circuit, the healthy winding pair automatically provides cushioning support to prevent overloading of circuit breakers, without requiring any additional protective equipment or complex control 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
This configuration effectively reduces short-circuit current and prevents overloading of circuit breakers while maintaining a cost-effective and space-efficient design, allowing for smaller, less expensive circuit breakers that are not overloaded during short circuits.
Implementation Method 1
at least one second pair of windings with a second low-voltage winding and a second high-voltage winding is provided for each phase strand, which is arranged at a distance from the first pair of windings, and each of the pairs of windings is arranged in the stray field of the other pair of windings, wherein a magnetic cross-coupling is formed between the windings of one pair of windings to those of the other
Data Source
Figure 1~3b
Figure 4~6b
Figure 7a~7b
AI summary
A wind turbine for generating electrical power with a system transformer (6) connected via a connecting line (4) and having at least one phase winding for supplying power to a grid (9). The system transformer (6) has a first and a second winding pair for each phase winding, wherein the second winding pair (65) is arranged at a distance from the first winding pair (61), and wherein each of the winding pairs (61, 65) is arranged in the stray field of the other winding pair (65, 61). This creates a magnetic cross-coupling between the winding pairs. Thus, two systems for power flow are formed. In the event of a short circuit in one of the two parallel systems, the effect is that the power flow then also occurs via the other parallel system due to the cross-coupling.However, due to the high impedance resulting from the coupling via the stray field, only a relatively small increase in the short-circuit current occurs, thus preventing overloading of the components.