Wind Turbine Grid Stability Control via Dynamic Power Limiting

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Solution Overview

Problem

Wind turbines contribute to grid instability due to unpredictable short-term wind speed fluctuations, which can cause significant frequency fluctuations in small or weak electrical grids, as they typically do not participate in primary frequency control and operate at partial load, leading to uncontrolled power production.

Innovation Solution

A method and control system for wind turbines that monitor grid stability and adjust operations to limit wind-caused power fluctuations by setting an upper limit on output power, achieved through blade-pitch adjustment and electrical control, ensuring the grid frequency remains within a stable range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If wind turbines operate at partial load to maximize energy capture, then energy utilization is improved, but power fluctuations increase causing grid instability

Engineering Contradiction:

Improveenergy captureVSAvoidgrid stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The control system dynamically adjusts the power output limit based on real-time grid stability conditions. When grid stability deteriorates, the system automatically reduces the power fluctuation limit, and when stability improves, it relaxes the limit. This dynamic adaptation allows the wind turbine to capture maximum energy during stable grid conditions while preventing instability during weak grid conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system continuously monitors grid stability parameters (such as frequency deviations and rate of change of frequency) and uses this feedback to adjust the power output limits. The control loop compares actual grid conditions against stability criteria and modifies the power fluctuation limits accordingly, creating a closed-loop control system that balances energy capture with grid stability.

Inventive Principle:

Principle #23Feedback

2Productivity

If wind turbines do not participate in primary frequency control to maintain optimal operation, then energy efficiency is improved, but grid frequency stability deteriorates

Engineering Contradiction:

Improveenergy efficiencyVSAvoidfrequency stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system proactively limits power fluctuations before they can cause significant frequency deviations. By pre-establishing power output limits based on grid stability assessment, the wind turbine prevents harmful power variations from occurring, rather than reacting after frequency instability has already developed. This preliminary action maintains both energy efficiency and frequency stability.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The control system acts as an intermediary between the wind turbine's power production and the electrical grid. It mediates the power flow by applying appropriate limits to fluctuations, allowing the wind turbine to operate efficiently while protecting the grid from destabilizing variations. The intermediary control layer decouples the direct connection between wind power variations and grid frequency variations.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If power output limits are imposed on wind turbines to stabilize the grid, then grid stability is improved, but energy production decreases

Engineering Contradiction:

Improvegrid stabilityVSAvoidenergy production

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system applies partial action by imposing power output limits only when grid stability conditions deteriorate, rather than continuously limiting power output. During stable grid conditions, the wind turbine operates without artificial limits and captures full available wind energy. The limitation is applied partially in time and magnitude, just sufficient to maintain stability without excessive energy curtailment.

Inventive Principle:

Principle #16Partial or excessive 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 reduces the impact of wind turbine output fluctuations on grid stability, maintaining frequency stability and reducing energy losses by limiting power output during unstable grid conditions while allowing optimal operation during stable conditions.

Implementation Method 1

Methodology Applied

Scientific EffectBlade-pitch adjustment:

Data Source

PatentUS9222466B2Wind-power production with reduced power fluctuations

Publication Date: 2015.12.29 VESTAS WIND SYSTEMS AS

AI summary

A method of operating at partial load a wind turbine (1) supplying electrical power to an electrical grid (20) includes monitoring stability of the grid; and upon detection of a reduced grid stability, changing operation of the wind turbine by limiting wind-caused fluctuations of the active-power supply to the electrical grid, or by reducing an already existing limit to fluctuations of the active-power supply.