Wind Turbine Grid-Forming Control With Torque Variation Limiting
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Solution Overview
Problem
The increasing use of renewable energy sources like wind turbines and photovoltaic systems in power grids leads to reduced inertia and stability, causing mechanical torque variations and increased fatigue loads on wind turbine components due to grid frequency disturbances, which can result in higher maintenance costs and safety issues.
Innovation Solution
A method and control system that limits torque variations by controlling the power converter system to stabilize grid frequency and voltage, using an energy storage device to absorb disturbance power and adjust the power converter operation to prevent excessive mechanical stress, and includes a control system to monitor and manage these variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power generation system operates in grid forming mode to support grid frequency and voltage, then grid stability is improved, but mechanical torque variations increase causing fatigue loads on components
Solution Approach 1:
The patent introduces an energy storage device as an intermediary between the generator and the grid. This device absorbs disturbance power and decouples the direct connection between electrical power fluctuations and mechanical torque variations, allowing the system to support grid frequency while protecting mechanical components from excessive stress
Solution Approach 2:
The patent extracts the disturbance power handling function from the main power generation system by introducing a separate energy storage device. This device specifically absorbs the disturbance power component, separating the grid support function from the mechanical torque transmission path
2Reliability
If the power converter system increases disturbance power exchange to support the grid during frequency disturbances, then grid frequency stability is improved, but torque variations of the generator increase
Solution Approach 1:
The energy storage device acts as a mediator that handles the disturbance power exchange with the grid, preventing these fluctuations from being directly transmitted to the generator. This allows the power converter system to increase disturbance power exchange for grid support while the energy storage device absorbs the resulting torque variations
Solution Approach 2:
The patent changes the operational parameters of the power converter system by controlling it to limit torque variations. The control system adjusts the converter operation to maintain electrical power output for grid support while keeping mechanical torque variations within acceptable limits through coordinated control with the energy storage device
3Power
If the wind turbine increases power output to counteract grid frequency drop, then grid support capability is improved, but mechanical fatigue loads on tower and rotor blades increase
Solution Approach 1:
The energy storage device serves as an intermediary that absorbs the disturbance power required for grid support, preventing this power fluctuation from being generated by the mechanical components. This allows the wind turbine to maintain high disturbance power output capability while the energy storage device protects the mechanical structure from associated fatigue loads
Solution Approach 2:
The patent replaces the mechanical system's direct response to grid disturbances with an electrical/electronic solution. Instead of the mechanical components (generator, tower, blades) directly handling disturbance power through torque variations, the energy storage device and power converter system handle this electrically, substituting mechanical stress with electrical energy management
Data Source
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AI summary
A method of controlling a power generation system (60) of a wind turbine (1) is provided. The power generation system (60) may be electrically coupled to a power grid (20) and may comprise a generator (10) generating electrical power and a power converter system (30) coupled to the generator (10) and the power grid (20). The method may comprise operating, by a control system, the power generation system (60) in a grid forming operation mode in which the power converter system (30) controls the exchange of electrical power with the power grid (20) to support a grid voltage and/or a grid frequency. The method further comprises limiting a variation of a torque of the generator (10) caused by a variation in electrical output power provided by the power generation system (60) to the power grid (20) by limiting variations of a stabilizing component of the output power and/or limiting variations in a disturbance power required to be supplied by the power generation system (60) to the power grid (20).