Wind Turbine Kit for Variable Speed Grid Connection

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Solution Overview

Problem

Fixed speed wind turbines face issues with vibrations transmitted to the electrical grid due to mechanical stiffness and inability to operate at variable speeds, leading to power fluctuations and increased grid connection demands, which affect availability and efficiency.

Innovation Solution

A kit comprising a back-to-back power converter and controller is used to convert a fixed speed wind turbine into a variable speed turbine, allowing operation independent of generator frequency and eliminating the need for additional equipment, thereby enhancing availability and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed speed wind turbine is coupled directly to the grid, then the generator frequency matches the grid frequency, but vibrations and torque pulsations are transmitted to the grid causing power fluctuations

Engineering Contradiction:

Improvegrid connection stabilityVSAvoidvibrations and torque pulsations

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A back-to-back converter system is introduced as an intermediary between the generator and the grid. The first converter connects to the generator and the second converter connects to the grid, with a DC link connecting both converters. This intermediary system decouples the mechanical vibrations from being transmitted to the electrical grid while maintaining stable power delivery.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The direct mechanical-electrical coupling is replaced with an electronic conversion system. Instead of directly coupling the generator to the grid through mechanical means, the patent uses power electronic converters to transform the mechanical energy to electrical energy and then to the grid, filtering out vibrations and torque pulsations in the process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If a fixed speed wind turbine operates at constant frequency, then the generator can be directly coupled to the grid, but the turbine cannot absorb wind gusts and delivers unstable power

Engineering Contradiction:

Improvepower delivery stabilityVSAvoidspeed variation capability

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The system transitions from fixed speed operation to variable speed operation through the back-to-back converter system. The first converter allows the generator to operate at variable speeds by converting the variable frequency AC power to DC power, which is then converted back to grid-frequency AC power by the second converter. This dynamic capability allows the turbine to absorb wind gusts and deliver stable power.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If additional equipment is installed to enable variable speed operation, then the turbine can absorb wind gusts and reduce torque strokes, but the device complexity and cost increase

Engineering Contradiction:

Improvevariable speed operationVSAvoidnumber of additional equipment

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The back-to-back converter system combines multiple functions into a single integrated solution. The first converter, second converter, and DC link work together as a unified system that simultaneously enables variable speed operation, filters vibrations, and ensures stable grid connection, reducing the need for separate additional equipment.

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If the generator frequency must equal the grid frequency, then the fixed speed turbine can connect to the grid, but the availability decreases due to inability to operate under varying wind conditions

Engineering Contradiction:

Improvegrid connection availabilityVSAvoidoperational efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system changes the operating parameters by allowing the generator frequency to vary independently from the grid frequency. The back-to-back converter system transforms the variable frequency AC power from the generator into constant frequency AC power for the grid, enabling the turbine to operate efficiently under varying wind conditions while maintaining reliable grid connection.

Inventive Principle:

Principle #35Parameter changes

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

The kit reduces torque pulsations and power variations, improves grid stability, and simplifies compliance with grid code requirements by enabling variable speed operation without additional equipment, increasing turbine availability and efficiency.

Implementation Method 1

a power converter (3), of the back-to-back type, connectable between the generator (10) and the grid (2)

Methodology Applied

Scientific EffectPower conversion:

Data Source

PatentEP3118452B1Kit for a wind station, and method

Publication Date: 2021.02.24 INGETEAM POWER TECH

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Figure 3~4
Figure 5

AI summary

Kit and method for a wind station comprising a fixed speed wind turbine with a generator being coupled to a grid by means of a coupling device so that the turbine operates at a fixed grid current frequency of the grid. The kit (100) is adapted to be coupled between the generator (10) of the wind turbine (1) and the grid (2), replacing at least the coupling device, the kit (100) turning the fixed speed wind turbine into a variable speed wind turbine.