Electrical Converter Control Tuning for Weak Grid Stability
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Solution Overview
Problem
The increasing dominance of low-inertia voltage source converters (VSCs) in electrical power grids leads to instability, as they lack rotating inertia and rely on synchronous generators that are being phased out, resulting in 'weak grids' prone to voltage instability and potential brown-outs or black-outs due to changing demand and renewable energy unpredictability.
Innovation Solution
The implementation of a Structured H-infinity tuning module to determine and provide control parameters for electrical converter systems, optimizing performance across varying grid conditions by minimizing the H-infinity norm, ensuring robustness against parameter variations and reducing coupling between power and voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If voltage source converters (VSCs) are used to replace synchronous generators, then renewable energy integration and electrical converter efficiency are improved, but grid stability and voltage robustness deteriorate due to lack of rotating inertia
Solution Approach 1:
The patent applies parameter changes by modifying controller parameters (kp, ki, kd, kw) based on grid conditions (SCR values). The controller dynamically adjusts its parameters to maintain stability as grid conditions change, transforming a static control system into an adaptive one that responds to varying grid strength and renewable energy penetration levels.
Solution Approach 2:
The invention implements dynamics by creating a dynamic controller that adapts to changing grid conditions. The controller parameters are no longer fixed but change dynamically based on the short circuit ratio and grid state, allowing the system to maintain stability during transitions from strong to weak grid conditions as renewable energy replaces synchronous generators.
2Object-affected harmful factors
If the number of synchronous generators is reduced, then emissions and energy security concerns are addressed, but voltage stability and grid robustness worsen due to decreased inertia
Solution Approach 1:
The patent implements feedback mechanisms where the controller continuously monitors grid conditions (voltage, frequency, SCR) and adjusts its parameters accordingly. This closed-loop feedback system allows the VSC to compensate for the lack of inertia from synchronous generators, maintaining voltage stability even as emissions-reducing renewable energy sources replace traditional generation.
Solution Approach 2:
The invention substitutes the mechanical inertia of synchronous generators with an electronic control system. Instead of relying on physical rotating mass to maintain stability, the system uses advanced control algorithms and parameter adaptation to provide synthetic inertia and voltage support, replacing mechanical stabilization with electronic control.
3Productivity
If remote area generation (off-shore sites) is increased, then renewable energy capacity is improved, but grid weakness increases leading to higher risk of voltage instability
Solution Approach 1:
The patent applies preliminary action by pre-configuring the controller with parameter adaptation capabilities before grid disturbances occur. The controller is designed to anticipate and respond to weak grid conditions, adjusting parameters proactively based on measured SCR values to prevent voltage instability rather than reacting after problems arise.
Solution Approach 2:
The invention segments the control function into multiple adaptive parameter sets (different kp, ki, kd, kw values) that can be selectively applied based on grid conditions. This segmentation allows the controller to optimize performance for specific operating conditions, particularly for remote off-shore applications where grid strength varies.
4Device complexity
If a single controller is used for varying grid conditions, then device complexity is reduced, but control performance and stability under worst-case scenarios deteriorates
Solution Approach 1:
The patent implements universality by designing a single controller that performs multiple functions through parameter adaptation. Rather than requiring separate controllers for different grid conditions, this universal controller can operate effectively across a wide range of SCR values and grid strengths by dynamically adjusting its parameters, maintaining high performance while reducing overall system complexity.
Data Source
AI summary
There is provided methods and apparatus configured to provide electrical converter control parameters, the apparatus comprising: a Structured H-infinity tuning module configured to determine one or more control parameters, for a model of an electrical converter control system and grid, based on variation of one or more grid parameters; and an output module configured to provide the one or more control parameters for implementation in the electrical converter control system.