Doubly Fed Induction Generator Rotor Speed Regulation

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Solution Overview

Problem

Wind turbines face limitations in increasing power output at reduced wind speeds due to voltage constraints in power converters, which restrict the operational efficiency and energy collection.

Innovation Solution

Regulating the rotational speed of the rotor in a doubly fed induction generator wind turbine system to maintain an optimum tip-speed ratio and manage rotor voltage within power converter limits, using sensors and control systems to adjust rotor speed based on voltage thresholds and reactive power demands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the rotational speed of the rotor is increased to increase power output, then the power output increases, but the rotor voltage exceeds the power converter voltage threshold

Engineering Contradiction:

Improvepower outputVSAvoidvoltage threshold violation

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the rotor speed adjustable and variable rather than fixed. The control system dynamically adjusts the rotor speed based on real-time wind conditions and power converter voltage thresholds, allowing the system to operate optimally across varying conditions while preventing voltage violations.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the wind turbine by adjusting the rotor speed to a regulated value that maintains the power converter voltage below the threshold. This parameter adjustment resolves the contradiction between maximizing power output and preventing voltage violations.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the rotor speed range is expanded to increase power output at reduced wind speeds, then the energy collection efficiency improves, but the power converter voltage may exceed safe limits

Engineering Contradiction:

Improveenergy collection efficiencyVSAvoidpower converter voltage safety

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements feedback control where the control system continuously monitors the power converter voltage and adjusts the rotor speed accordingly. This feedback mechanism ensures that the rotor speed is regulated to maintain voltage within safe limits while maximizing energy collection efficiency across different wind speed conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically regulates rotor speed based on real-time voltage measurements and wind conditions, allowing the wind turbine to expand its operational speed range for improved productivity while maintaining reliability through active voltage control.

Inventive Principle:

Principle #15Dynamics

3Productivity

If variable speed operation is used to optimize tip-speed ratio and improve turbine output, then the wind energy collection improves, but the power converter voltage constraints limit the operational speed range

Engineering Contradiction:

Improveturbine outputVSAvoidoperational speed range

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent changes the rotor speed parameter to a regulated value that optimizes the tip-speed ratio for maximum wind energy capture while ensuring the power converter voltage remains within acceptable limits. This parameter optimization resolves the contradiction between improving productivity and maintaining adaptability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

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

This approach enhances the power output of wind turbines at reduced wind speeds by expanding the rotor speed range, ensuring efficient energy collection while maintaining power converter voltage within safe limits, thereby improving overall wind energy harvesting.

Implementation Method 1

The rotor blades can transform wind energy into a mechanical rotational torque that drives one or more generators via the rotor

Methodology Applied

Scientific EffectAerodynamic forces: Aerofoil

Implementation Method 2

The one or more generators can be, for instance, coupled to the rotor via a gearbox. The gearbox can step up the inherently low rotational speed of the rotor such that the generator can efficiently convert the mechanical rotational energy to electrical energy

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3034868B1Systems and methods for increasing wind turbine power output

Publication Date: 2020.12.30 GENERAL ELECTRIC CO

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AI summary

Systems and methods 300 for increasing the power output of wind turbines 100 in a wind farm 200 are disclosed. In particular, a wind farm 200 can include first and second doubly fed induction generator 120 wind turbine systems. The rotational rotor speed of the first wind turbine system 100 can be regulated at reduced wind speeds based at least in part on data indicative of rotor voltage to increase power output of a doubly fed induction generator 120. The rotor speed can be regulated such that the rotor voltage does not exceed a voltage threshold. The power output of the first wind turbine system 100 can be further increased by reducing its reactive power output. The reduced reactive power output of the first wind turbine system 100 can be compensated for by an increased reactive power output of the second wind turbine system 100.