Wind Power Converter Structure with Segmented Grid-Side Converters
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Solution Overview
Problem
Conventional wind power converter structures face challenges in balancing nacelle load design, ensuring operation reliability, and reducing installation costs, particularly due to increased cable costs and safety risks associated with high tower maintenance for larger wind turbines.
Innovation Solution
A wind power converter structure featuring generator-side converters in the nacelle on the tower top and grid-side converters on the tower bottom or outside, connected via a DC bus, with multiple three-phase PWM rectifiers and inverters arranged in parallel for redundancy, and an isolation transformer for AC voltage transfer, reducing cable costs and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the wind power converter is arranged in the top part of the tower, then the nacelle load design is balanced, but the maintenance safety risk increases and maintenance cost increases
Solution Approach 1:
The converter system is divided into modular units (converter common rail, converter modules) that can be independently installed and maintained. The converter common rail is fixed to the tower body while converter modules can be accessed from ground level, separating the load-bearing structure from the maintainable components.
Solution Approach 2:
A converter common rail acts as an intermediary structure fixed to the tower body, providing mechanical support and electrical connection points. This rail allows the converter modules to be coupled to the tower without requiring maintenance personnel to access the top of the tower, thus mediating between the need for top-mounted conversion and ground-level maintenance.
2Reliability
If the wind power converter is arranged in the bottom part of the tower, then the maintenance safety risk is reduced, but the cable cost increases
Solution Approach 1:
The converter modules are positioned in a intermediate dimension - coupled to the tower body at a height that allows ground-level access for maintenance, rather than being strictly at the top or bottom. This dimensional positioning optimizes both cable length and maintenance accessibility.
Solution Approach 2:
The converter common rail serves as an intermediary that provides electrical connection points along the tower body, allowing converter modules to be positioned optimally for both cable length minimization and maintenance accessibility, rather than requiring all components at extreme positions.
3Power
If the rated power of the wind power turbine is increased, then the power generation capacity increases, but the gear ratio of the gearbox increases causing increased dimension, weight and frictional wear
Solution Approach 1:
The mechanical gearbox is replaced with an electrical power conversion system consisting of converter modules with PWM rectifiers and inverters. This substitution eliminates the need for high-ratio mechanical gearboxes, removing the associated weight, dimension, and frictional wear problems while maintaining the ability to handle high rated powers.
Solution Approach 2:
The system changes from mechanical parameter transmission (gear ratios) to electrical parameter conversion (frequency and voltage conversion via PWM converters). This parameter change allows high power transmission without the physical constraints of mechanical gear systems.
4Reliability
If multiple PWM rectifiers and inverters are arranged in parallel for redundancy, then the operational reliability is improved, but the device complexity increases
Solution Approach 1:
The converter system is segmented into independent converter modules, each containing a PWM rectifier and inverter. These modular units can be configured in parallel for redundancy, with each module being independently controllable and maintainable, thus managing complexity through standardization.
Solution Approach 2:
Each converter module is designed as a universal, multi-functional unit that can operate independently or in combination with other modules. The standardized design of converter common rail and modules allows flexible configuration for different power levels and redundancy requirements without increasing per-module complexity.
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 reduces cable costs, balances nacelle load, and improves operational reliability by enabling redundant operation of PWM rectifiers and inverters, ensuring continued functionality even if one unit fails.
Implementation Method 1
The AC input side of the generator-side converter is connected to a three-phase winding of the wind power generator, and the DC output side of the generator-side converter outputs a DC voltage
Implementation Method 2
Each grid-side converter has a DC input side and an AC output side. The DC input side of the grid-side converter is coupled to the DC output side of the generator-side converter
Implementation Method 3
The primary side of the isolation transformer is electrically connected to the AC output side of the grid-side converter, and the secondary side of the isolation transformer is electrically connected to a power grid
Data Source
AI summary
A wind power converter structure and a wind power generation system including the converter structure are provided. The converter structure includes a plurality of generator-side converters arranged in a nacelle located on a top part of the tower; a plurality of grid-side converters arranged on a bottom part of the tower or outside the tower, wherein a DC input side of the grid-side converter is coupled to a DC output side of the generator-side converter; at least one DC bus connected between the generator-side converter and the grid-side converter; and an isolation transformer of which a primary side is coupled to the AC output side of the grid-side converter, wherein a secondary side of the isolation transformer is coupled to a power grid.