Wind Turbine Electrolyser Control for Stable DC-Link Voltage
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Solution Overview
Problem
The challenge in the DC-coupled hydrogen electrolyser system powered by a wind turbine generator is the significant increase in internal resistance of the electrolyser at low voltages, leading to reduced current and torque in the generator, which can cause unbalanced loads, noise, and improper rotor speed control.
Innovation Solution
The system incorporates a control system that manages the primary and auxiliary power converters to regulate the voltage on the DC-link within a predetermined range, optimizing hydrogen production by varying the number of active cells in the electrolyser based on available wind power, thereby decoupling the electrolyser's performance from varying wind conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electrolyser is directly connected to the wind turbine generator in a DC-coupled arrangement, then cost is reduced and electrical efficiency is improved, but the internal resistance of the electrolyser increases significantly at low voltage leading to reduced current and torque
Solution Approach 1:
The system dynamically adjusts the number of active electrolyser cells based on available wind power and operating conditions. At low wind speeds, fewer cells are activated to maintain optimal current density and prevent excessive internal resistance, while at higher wind speeds more cells are activated to utilize available power. This dynamic adaptation resolves the contradiction by allowing the system to maintain both efficiency and torque stability across varying operating conditions.
Solution Approach 2:
The control system modifies operating parameters including the number of active cells, current density, and voltage levels based on real-time wind conditions. By changing these parameters dynamically, the system optimizes the balance between electrical efficiency and torque stability, preventing the harmful effects of high internal resistance at low voltages while maximizing hydrogen production when conditions are favorable.
2Productivity
If the number of active cells in the electrolyser is increased, then hydrogen production capacity is improved, but the current density decreases leading to reduced efficiency
Solution Approach 1:
The system employs dynamic control of the number of active electrolyser cells based on real-time operating conditions including wind power availability and current density requirements. The control algorithm continuously adjusts cell activation to maintain optimal current density thresholds, ensuring that hydrogen production capacity scales with available power while efficiency is preserved through appropriate current density management.
3Loss of energy
If the current density in the electrolyser is maintained at a narrow range, then hydrogen production efficiency is optimized, but the adaptability to varying wind power conditions is reduced
Solution Approach 1:
The control system dynamically adjusts the number of active electrolyser cells in response to varying wind power conditions while maintaining current density within an optimized range. When wind power increases, additional cells are activated rather than increasing current density beyond optimal levels, allowing the system to adapt to power variations while preserving efficiency.
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
This solution ensures optimized hydrogen production by regulating the power supplied to the electrolyser and varying the number of active cells, maintaining a narrow range of current density and improving the system's efficiency and stability, even at low wind turbine rotor speeds.
Implementation Method 1
hydrogen production via water electrolysis
Implementation Method 2
wind turbine rotor coupled to a generator
Data Source
AI summary
A hydrogen generation system comprising a wind turbine rotor coupled to a generator, wherein the generator is electrically coupled to a DC-link by way of a primary power converter, the DC-link having a power dissipation element. The system also comprises a hydrogen electrolysis system coupled to the DC-link; an auxiliary power converter coupled to the DC-link; and one or more auxiliary loads. A control system controls the voltage on the DC-link to remain with a predetermined range. In one aspect, the system provides power to at least the auxiliary loads, in such a way as to manage the generation of hydrogen by the electrolyser whilst decoupling the performance of the electrolyser from varying wind conditions.