Wind Turbine Inertia Control via Frequency Rate Emulation
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Solution Overview
Problem
Variable speed wind turbines lack the natural inertial response to grid frequency changes, leading to frequency drops/spikes and an inability to buffer these changes, which poses challenges for grid stability as they do not deliver stored rotational energy effectively like synchronous generators.
Innovation Solution
A wind turbine controller system that emulates inertial response by generating a power signal proportional to the frequency change rate, adapting the rotational speed reference, and limiting power delivery to match stored inertial energy, thereby preventing a 'recovery period' that can cause undesired frequency drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable speed wind turbines use electronic converter controllers to uncouple frequency from generator rotational speed, then the wind turbines can operate at variable speeds to maximize power generation, but they lose the natural inertial response to grid frequency changes
Solution Approach 1:
The patent replaces the natural mechanical inertial response of synchronous generators with an electronic control system that calculates and injects artificial inertial response signals. The controller computes the inertial response based on frequency deviation and its rate of change, then adjusts the power converter to deliver the corresponding power adjustment, substituting electronic control for mechanical inertia.
Solution Approach 2:
The patent introduces an intermediary inertial response controller between the grid frequency signal and the power converter. This intermediary component processes the frequency deviation signal, calculates the required inertial response, and translates it into control signals for the power converter, acting as a mediator that enables variable speed operation while maintaining grid frequency stability.
2Reliability
If wind turbines deliver additional power quickly to match inertial response, then grid frequency stability is improved, but the wind turbine rotational speed deviates from reference speed causing aerodynamic efficiency loss
Solution Approach 1:
The patent implements dynamic adjustment of the wind turbine's operational parameters by continuously adapting the rotational speed reference based on grid frequency conditions. During frequency transients, the controller dynamically modifies the speed reference to enable rapid power delivery, then restores the original reference after the transient event, allowing the system to optimize performance for different operating conditions.
Solution Approach 2:
The patent changes the operational parameters of the wind turbine by adjusting the rotational speed reference and power output in response to grid frequency deviations. The controller modifies these parameters dynamically during frequency transients to deliver inertial response, then returns them to normal operating values, enabling the system to balance grid support requirements with aerodynamic efficiency.
3Reliability
If wind turbines are rigidly connected to the grid like synchronous generators, then they provide natural inertial response, but variable speed operation and maximum power extraction are limited
Solution Approach 1:
The patent replaces the mechanical rigid connection that provides natural inertia with an electronic control system that synthesizes inertial response. The power converter and controller work together to create an artificial inertial effect through rapid power adjustment, substituting electronic control for mechanical coupling while maintaining the beneficial inertial response characteristics.
Solution Approach 2:
The patent introduces an intermediary control system between the wind turbine generator and the grid that provides inertial response functionality without requiring rigid mechanical coupling. This intermediary controller processes grid frequency signals and adjusts power converter operation accordingly, enabling variable speed operation while maintaining grid synchronization and providing inertial support.
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
The system ensures stable grid frequency by delivering additional power dynamically and quickly, matching the inertial response of synchronous generators, thereby preventing frequency drops and maintaining grid stability without the recovery period issues.
Implementation Method 1
A wind turbine controller system that emulates inertial response by generating a power signal proportional to the frequency change rate
Data Source
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AI summary
Inertia control system for a wind turbine comprising a rotor (5), generator (12) driven by the rotor (5) that interacts with a power converter (13) to generate electricity, a wind turbine controller (15) that comprises a blade pitch controller (19) and a generated power controller (18), a controller for the power converter (14) that interacts with the wind turbine controller (15), characterized because it comprises an inertia emulation block (17) that generates an extra power signal (32) negatively proportional to the frequency change rate (23) that is added to the power reference of the wind turbine generated power controller (15) and adapts the rotational speed reference of the wind turbine controller (15) according to the grid frequency (21) to prevent distortion in the active power output after adding or subtracting power in proportion to the frequency change rate (23).