Electrolyser DC Link Control for Low-Voltage Ride-Through
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrolyser plants experience shutdowns during low voltage events in AC power networks, leading to instability and potential damage, and require significant frequency restoration reserves, which are costly and inefficient.
Innovation Solution
An electrolyser plant with a DC link and AC/DC power converter, along with optional DC/DC converters and energy storage devices, maintains operation by controlling load current and voltage during low voltage events, using stored energy to sustain production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrolyser plant shuts down during low voltage events, then the plant is protected from damage, but network stability deteriorates and frequency restoration reserves are required
Solution Approach 1:
The patent applies preliminary action by maintaining the electrolyser plant in operation during low voltage events rather than shutting down immediately. The plant continues operating through the voltage dip, avoiding sudden load changes that would require frequency restoration reserves. This is achieved by designing the plant to tolerate voltage variations within specified thresholds, thereby preventing network instability before it occurs.
2Stability of the object's composition
If the electrolyser plant continues operation during low voltage events, then network stability is maintained, but the plant may experience damage or degradation
Solution Approach 1:
The patent applies parameter changes by defining specific voltage thresholds (e.g., 0.95 pu to 0.05 pu) and time durations that determine whether the plant should continue operation or shut down. By monitoring voltage parameters in real-time and comparing them against predefined limits, the system dynamically adjusts its operation mode to balance network stability requirements with plant protection requirements.
3Reliability
If the electrolyser plant shuts down and restarts after low voltage events, then plant damage is avoided, but production time is lost and efficiency decreases
Solution Approach 1:
The patent applies continuity of useful action by enabling the electrolyser plant to maintain operation throughout low voltage events rather than shutting down and restarting. The plant continues producing hydrogen and oxygen continuously, avoiding the hour-long restart period that would otherwise be required. This is achieved by designing the plant with sufficient voltage ride-through capability to withstand the low voltage condition without damage.
4Stability of the object's composition
If frequency restoration reserves are deployed to compensate for sudden load loss, then network frequency is stabilized, but operating costs increase
Solution Approach 1:
The patent applies preliminary anti-action by preventing the sudden load loss that would otherwise require frequency restoration reserves. The electrolyser plant is designed to maintain operation during low voltage events, thereby preemptively avoiding the need for costly frequency restoration measures. This anticipatory approach eliminates the requirement for stand-by power reserves and reduces operating costs associated with frequency management.
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 continuous hydrogen and oxygen generation during low voltage events, reducing the need for frequency restoration reserves and minimizing plant downtime.
Implementation Method 1
an AC/DC power converter comprising: at least one AC terminal electrically connectable to an AC power network, and at least two DC terminals electrically connected to the first DC link
Implementation Method 2
a first DC link with at least one DC link capacitor
Implementation Method 3
each stack has one or more electrolyser cells that generate hydrogen and oxygen when a direct current (DC) voltage is applied across the stack
Data Source
AI summary
Provided is an electrolyser plant that includes a first DC link with a DC link capacitor and an AC/DC power converter and an electrolyser electrically connected to the first DC link to receive a load current. During normal operation of an AC power network, a controller maintains a pre-event DC link voltage and supplies a pre-event load current to the electrolyser and in response to a detected low voltage event, the controller initially supplies the pre-event load current to the electrolyser to maintain normal operation of the electrolyser, monitors the DC link voltage, and when the monitored DC link voltage falls below a first voltage threshold less than the pre-event DC link voltage, reduces the load current supplied to the electrolyser, by ramping down the load current at a suitable ramp rate.