Wind Plant Power Reference Limiting During Over-Frequency Events

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Solution Overview

Problem

Wind turbines in power plants face challenges in controlling power production during grid frequency faults, particularly over frequency events, where changes in available wind power can lead to unintended increases in power production, potentially worsening the frequency imbalance.

Innovation Solution

A method is implemented to control power plants with wind turbines by determining a power reference, modifying it based on detected events, memorizing a power level, setting power limits, and gradually changing the power production to prevent unintended changes, ensuring that power production does not exceed or decrease beyond set limits during grid frequency events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If wind turbines are controlled to produce power according to available wind power in a given control mode, then the power production follows wind availability, but unintended power increases occur during over frequency events worsening grid stability

Engineering Contradiction:

Improvepower production adaptability to wind availabilityVSAvoidgrid frequency stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary action by memorizing the power level at the time of the first event (over frequency detection) before any further power changes occur. This memorized power level serves as a reference to prevent unintended power increases during the event, ensuring that power production does not exceed the level that caused the frequency deviation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system implements feedback by continuously monitoring power production against the memorized power level and adjusting the power reference accordingly. During the over frequency event, the system compares actual power output with the memorized reference and applies corrective actions to maintain power within acceptable limits, thereby stabilizing grid frequency.

Inventive Principle:

Principle #23Feedback

2Reliability

If the power reference is changed by a power variation in response to detecting an over frequency event, then power production is reduced to support grid frequency, but power production may still increase due to wind gusts exceeding the reduction

Engineering Contradiction:

Improvegrid frequency supportVSAvoidpower production control precision

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system applies preliminary anti-action by setting a power limit based on the memorized power level before wind gusts can cause unintended power increases. This pre-established limit acts as a countermeasure that prevents power production from exceeding the level that would worsen the frequency deviation, even when wind conditions change unfavorably.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The control system dynamically adjusts the power reference by combining the modified power reference (reduced by power variation) with the power limit (memorized power level). This dynamic approach ensures that power production responds appropriately to both grid frequency requirements and actual wind conditions, maintaining control precision during variable wind scenarios.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If the modified power reference is gradually changed towards available power over a period of time after detecting the second event, then power production returns to normal gradually, but the return time is extended

Engineering Contradiction:

Improvepower production stabilityVSAvoidtime to return to normal power production

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The system implements periodic action by gradually changing the modified power reference towards available power over a defined period of time after the second event (end of over frequency condition). This staged approach allows the power production to return to normal levels in controlled increments, preventing sudden transitions that could destabilize the grid while ultimately restoring full power output.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12166356B2Controlling a power plant comprising wind turbines during grid frequency deviation

Publication Date: 2024.12.10 VESTAS WIND SYSTEMS AS

AI summary

The invention relates to a method for controlling a power plant during an event which requires a change of the power produced by the power plant, wherein the power plant comprises a plurality of power generating units including at least one wind turbine generator, the method comprises determining the power reference dependent on an available power, changing the power reference to a modified power reference by a power variation in response to detecting a first event, memorizing a power level relating to the actual power production at a time occurrence of the first event, setting a maximum power limit to the memorized power level, limiting the modified power reference to the maximum power limit, and controlling the power produced by the wind turbines in accordance with the limited modified power reference.