Wind Turbine Reactive Power Support via Active Power Derating

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Solution Overview

Problem

Traditional methods struggle to provide fast reactive power support to a power grid when a wind turbine is operating at or near its rated power level, as it often exceeds the turbine's current limit, leading to potential damage and grid instability.

Innovation Solution

A method that involves increasing reactive power injection into the grid by decreasing active power and dissipating or storing the reduced active power using DC choppers and batteries/capacitors, while maintaining the wind turbine's load constant to avoid exceeding current limits and stabilize the grid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reactive power support is launched while the wind turbine is operated at or near its rated power level, then reactive power support is provided to the power grid, but the overall current limit of the wind turbine is exceeded causing potential damage

Engineering Contradiction:

Improvereactive power support capabilityVSAvoidcurrent limit exceedance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the operating parameters by derating the wind turbine from its rated power level to a lower power level, thereby creating available current headroom. This parameter change allows the wind turbine to provide reactive power support without exceeding its current limits, as the derated state reduces the active power component of the current, leaving capacity for reactive power injection.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention implements dynamic control by continuously adjusting the reactive power output based on real-time monitoring of current levels and grid voltage conditions. The system dynamically balances active and reactive power components to maintain operation within current limits while maximizing reactive power support capability, transforming a static rated operation into a dynamic adaptive operation.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If the wind turbine is slowly derated to provide reactive power support, then current limits are not exceeded, but grid instability occurs and rotor speed increases requiring blade pitching

Engineering Contradiction:

Improvecurrent limit complianceVSAvoidgrid stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The invention applies preliminary action by pre-establishing derating protocols and control strategies before grid disturbances occur. The system is pre-configured with derating curves and reactive power injection profiles that can be immediately activated during voltage dips or grid disturbances, eliminating the need for slow gradual derating and associated instability. This preliminary preparation enables rapid response while maintaining stability.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If the wind turbine provides fast reactive power support, then grid instabilities are avoided, but the current limit is exceeded

Engineering Contradiction:

Improvegrid stabilityVSAvoidcurrent limit exceedance

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The invention applies the counterweight principle by using the derated active power level as a counterbalance to the reactive power injection. By reducing the active power component, the system creates current headroom that counterweights the current increase from reactive power injection, allowing fast reactive power support without exceeding overall current limits. This balancing act enables simultaneous achievement of fast response and current limit compliance.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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

Enables swift and stable reactive power support without exceeding current limits, preventing grid instability and rotor speed increases, even when the wind turbine is at rated power, thus avoiding the need for costly standby devices like StatComs.

Implementation Method 1

The power source is typically a wind turbine facility, such as a single wind turbine or a wind power plant

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The power dissipation means may comprise a DC chopper comprising a number of dump load resistors

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

the power storage means may comprise a number of batteries and/or capacitors

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 4

the power storage means may comprise a number of batteries and/or capacitors

Methodology Applied

Scientific EffectBattery (electricity): Battery (electricity)

Data Source

PatentUS10236686B2Reactive power support from wind turbine facilities

Publication Date: 2019.03.19 VESTAS WIND SYSTEMS AS

AI summary

Techniques are described for operating a wind power facility in order to provide reactive power support to a power grid. The wind power facility may be a wind turbine or a wind power plant. An exemplary method includes increasing an amount of reactive power injected into the power grid, decreasing an amount of active power injected into the power grid by a certain amount, and dissipating and/or storing substantially the certain amount of active power.