Wind Turbine Frequency Control via Dynamic Load Shifting

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Solution Overview

Problem

Wind turbine generators contribute to grid instability due to unpredictable short-term wind power fluctuations, as they typically do not participate in primary frequency control and can only maintain constant output at nominal wind speeds, leading to challenges in balancing power production and consumption in electrical grids.

Innovation Solution

A method for operating an electrical power system that includes setting technical requirements and limits, distributing power reserves between conventional and wind power sources, and using a wind power controller to manage frequency fluctuations, allowing for wind power curtailment and optimizing power tracking to maintain grid stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If wind turbine generators operate at optimal working point or nominal load to maximize power extraction, then energy utilization is improved, but grid stability deteriorates due to inability to increase output power by command and transformation of wind-speed fluctuations into power fluctuations

Engineering Contradiction:
Improvepower extraction efficiencyVSAvoidgrid stability
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The wind turbine generator operates dynamically between optimal working point and nominal load based on grid frequency conditions. During normal operation, it operates at optimal working point for maximum energy extraction. When grid frequency deviates from nominal value, it transitions to nominal load operation where it can maintain constant output power and participate in frequency control, thus resolving the contradiction between energy efficiency and grid stability

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system changes operational parameters (power setpoint, rotor speed) based on grid frequency deviations. When frequency falls below nominal value, the wind turbine increases power output by transitioning from optimal working point to nominal load operation, thereby contributing to primary frequency control while maintaining stable operation

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If wind turbine generators operate at nominal load to maintain constant output power, then grid stability is improved, but energy utilization deteriorates when wind speed is below nominal wind speed

Engineering Contradiction:
Improvegrid stabilityVSAvoidpower extraction efficiency
Core Design Contradiction:
Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The wind turbine dynamically adjusts its operating mode based on wind speed and grid frequency. When wind speed is below nominal, it operates at optimal working point for maximum energy extraction. When wind speed reaches nominal value and grid frequency requires support, it transitions to nominal load operation for constant power output and frequency control participation

Inventive Principle:
Principle #15Dynamics

3Stability of the object's composition

If conventional power plants provide primary power control to stabilize frequency, then grid stability is improved, but the need for coordination with wind power plants increases system complexity

Engineering Contradiction:
Improvefrequency stabilityVSAvoidcoordination complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The wind turbine generator is designed with multi-functionality: it performs both optimal energy extraction and primary frequency control functions. By equipping wind turbines with frequency-dependent control capabilities, the system reduces dependence on conventional power plants for frequency stabilization, thereby simplifying overall system coordination while maintaining frequency stability

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2847844B1Method for coordinating frequency control characteristics between conventional plants and wind power plants
Publication Date: 2018.11.21 VESTAS WIND SYSTEMS AS
  • EP2847844B1 patent drawingFigure 1
  • EP2847844B1 patent drawingFigure 2~3
  • EP2847844B1 patent drawingFigure 4

AI summary

The present invention relates to a method for operating an electrical power system, comprising at least one wind turbine generator and at least one other power source, the method comprises the steps of, setting a set of technical requirements and limits for the electrical power system, including a total power reserve and at least one of: maximum electrical frequency deviation and allowable wind power electrical frequency fluctuations, distributing the total power reserve between the at least one other power source and a total wind power capacity available from the at least one wind turbine generator, and calculating in response thereto an amount of power reserve from the at least one wind turbine generator, and providing settings for a wind power controller, the settings comprising the set of technical requirements and the amount of power reserve from the at least one wind turbine generator. The invention also relates to a power plant operating according to the method.