Wind Turbine Rectifier Inverter Segmentation for Power Handling
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Solution Overview
Problem
Conventional wind turbine generators are limited by the power handling capacity of single rectifiers and inverters, leading to restricted power levels and increased current losses due to the concentration of current in a single path, which also results in higher conductor thickness, weight, and cost. Additionally, they face issues with common-mode noise and voltage surges that can cause electromagnetic interference and damage.
Innovation Solution
The system employs multiple rectifiers and inverters connected in pairs to split the power and current into multiple paths, with a neutral d.c. conductor to reduce current losses and common-mode noise, and includes surge protection and feedback control to balance currents and manage faults, while locating inverters at the base of the tower to minimize weight and torsional stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single rectifier is used to convert a.c. power to d.c. power, then the converter structure is simple, but the power handling capacity is limited and current losses are increased
Solution Approach 1:
The patent divides the single rectifier function into multiple rectifiers (first and second rectifiers) that operate in parallel. Each rectifier handles a portion of the total power, reducing the current burden on each individual rectifier and conductor path. This segmentation increases overall power handling capacity while reducing current losses through distribution across multiple paths.
2Power
If a single rectifier handles all current, then the conductor configuration is simple, but the conductor thickness and weight increase
Solution Approach 1:
The patent introduces a three-conductor configuration (positive, neutral, negative) that distributes current across multiple parallel paths. By splitting the current flow through the first and second rectifiers and their respective conductor paths, the current density in each conductor is reduced, allowing for thinner and lighter conductors while maintaining the same power handling capacity.
3Power
If multiple rectifiers are used to increase power handling, then the power capacity increases, but the device complexity increases
Solution Approach 1:
The patent employs two rectifiers with a structured three-conductor connection scheme (positive, neutral, negative). While this increases component count, the systematic arrangement and clear functional division between the rectifiers provide manageable complexity. The neutral conductor serves as a common reference point that simplifies the overall system architecture.
4Ease of operation
If the entire current is supplied through a single path, then the system is simple, but the current losses and conductor requirements increase
Solution Approach 1:
The patent creates two distinct current paths through the first and second rectifiers, each with its own conductor connections. This segmentation of the current flow distributes the electrical load, reducing resistive losses in each path while maintaining operational simplicity through the organized three-conductor system.
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 allows for higher power handling with reduced current losses, thinner conductors, and lower noise levels, while providing fault tolerance and efficient power management, reducing the weight and cost of equipment and minimizing torsional stresses during yaw rotation.
Implementation Method 1
A typical converter comprises a single rectifier which converts the three-phase a.c. voltage from the wind turbine to a d.c. voltage
Data Source
AI summary
A wind turbine generator 1 supplies three-phase a.c. current of variable voltage and variable frequency to two pairs of rectifiers 4a, 4b and 4c, 4d which generate respective d.c. outputs connected to positive, negative and neutral d.c. conductors 6, 7, 8. The outputs from each pair of rectifiers are connected together, and the outputs from the two pairs are connected in series to create a high-voltage d.c. output. Inverters 10a, 10b, 10c, 10d then convert the d.c. power to a.c. at a fixed frequency and voltage suitable for connection to the mains grid. To reduce the effect of common-mode noise, a capacitor is connected between the 1 neutral conductor 7 and earth, and a respective filter circuit 30 is connected between each of the a.c. outputs of the inverters 10a, 10b, 10c, 10d and earth. To reduce the effect of voltage surges during lightning, a surge protection device is also connected between the neutral d.c. conductor 7 and earth. Any imbalance in the current in the positive and negative conductors 6, 8 is compensated by detecting the presence of current flowing in the neutral conductor 7. Power supplied to auxiliary circuits from the output of one of the inverters, e.g. 10a, of the wind turbine is measured, and any resulting imbalance between the current in the positive and negative conductors is compensated. In the event of an earth-leakage fault in the conductors connecting the a.c. outputs of the inverters to the grid, when isolated, isolation detection relays 25 are provided.