Wind Turbine Grid Frequency Support via Rotational Energy Inversion

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Solution Overview

Problem

Wind turbines do not effectively support grid frequency stability during minor deviations, as they are typically switched off or operate at reduced power when the grid frequency falls below a certain threshold, rather than providing increased power to balance fluctuations.

Innovation Solution

Wind energy installations continue to operate with increased power, up to 20% above nominal, when the grid frequency drops below a setpoint, utilizing stored rotational energy to provide short-term support by increasing power output when the frequency falls below a predetermined value or shows a significant drop.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wind turbines are switched off or operate at reduced power when grid frequency falls below threshold, then system protection is improved, but grid frequency stability deteriorates

Engineering Contradiction:

Improvesystem protectionVSAvoidgrid frequency stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Instead of reducing power when frequency drops (conventional approach), the patent inverts the logic by increasing power output when grid frequency falls below the nominal value. This inverse response provides frequency support and helps stabilize the grid during frequency deviations.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The control system continuously monitors grid frequency and prepares to increase power output before significant frequency instability occurs. When frequency drops below nominal, the system immediately responds by increasing power, preventing further frequency degradation.

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If wind turbines increase power output during frequency dips, then grid frequency stability is improved, but mechanical stress on the installation increases

Engineering Contradiction:

Improvegrid frequency stabilityVSAvoidmechanical stress

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The patent implements dynamic control where power output is adjusted in real-time based on grid frequency conditions. The system increases power only when frequency drops below nominal and maintains this increased output only for the duration of the frequency event, rather than operating at constant high power, thereby reducing cumulative mechanical stress.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control system changes operational parameters (power output) in response to frequency deviations. By adjusting power output as a function of grid frequency, the system provides frequency support while managing mechanical stress through controlled parameter variation rather than sustained high-stress operation.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If wind turbines operate at increased power continuously, then grid support is improved, but energy efficiency deteriorates

Engineering Contradiction:

Improvegrid supportVSAvoidenergy efficiency

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The system operates at increased power periodically - only when grid frequency drops below nominal value - rather than continuously. This periodic increased operation provides necessary grid support during frequency events while maintaining normal operation during stable conditions, thereby preserving energy efficiency.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The control system maintains continuous monitoring of grid frequency and ensures continuous readiness to provide frequency support. The useful action of frequency support is activated continuously when needed, providing reliable grid support without unnecessary energy consumption during normal frequency conditions.

Inventive Principle:

Principle #20Continuity of useful action

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 helps stabilize grid frequency by providing additional power during frequency dips, improving grid support and reducing the need for other management interventions, while maintaining system stability without damaging the wind energy installation.

Implementation Method 1

the rotational energy stored in the moment of inertia of the rotor/generator system is used, i.e. more power is extracted from the entire rotor/generator system for a short time

Methodology Applied

Scientific EffectMoment of inertia: Moment of Inertia

Data Source

PatentEP2647840B1Method for operating a wind turbine

Publication Date: 2023.07.19 WOBBEN PROPERTIES GMBH

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AI summary

For the operation of a wind turbine, to generate electricity, the power output from the turbine generator to the electricity grid is raised temporarily and for a short time span above the actual turbine power if the grid frequency of the electricity grid is below the nominal grid frequency by a given frequency level and/or if the grid frequency has a frequency gradient with a time change exceeding a given change value. The wind turbines are controlled individually or centrally.