Hybrid Converter Startup Control for Electrolyzer Power Supplies
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Solution Overview
Problem
Existing power supply systems for electrolyzing plants face challenges in safely controlling the starting and shutdown sequences, particularly with thyristor-based converters, which struggle to manage reactive current and voltage, leading to potential inefficiencies and risks during electrolysis processes.
Innovation Solution
A hybrid power supply system combining thyristor-based and transistor-based converters, controlled by a specific sequence to manage reactive power, allowing for safe and efficient operation, including a starting sequence that progressively increases DC system voltage and a shutdown sequence that reduces voltage smoothly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thyristor-based converter is used to supply power to the electrolyzing device, then the device can establish the electrolyzing process, but the thyristor-based converter struggles to manage reactive current and voltage leading to potential inefficiencies and risks
Solution Approach 1:
The patent combines a thyristor-based converter with two transistor-based converters (first and second) to form a hybrid power supply system. The thyristor-based converter handles the electrolyzing voltage supply, while the transistor-based converters manage reactive power compensation. This merging allows the system to leverage the strengths of each converter type: the thyristor-based converter provides stable DC voltage for electrolysis, while the transistor-based converters efficiently manage reactive current and voltage, thereby improving both reliability and productivity.
Solution Approach 2:
The transistor-based converters are designed to perform multiple functions: they provide reactive power compensation to the AC grid and simultaneously supply active power to the electrolyzing device. The first transistor-based converter operates in capacitive reactive power mode while the second operates in inductive reactive power mode, allowing the system to universally handle both power factor correction and power supply functions, improving overall system efficiency and reliability.
2Productivity
If the power supply device uses a hybrid configuration with multiple converters, then reactive power can be managed effectively, but the device complexity increases
Solution Approach 1:
The power supply system is segmented into distinct functional modules: a thyristor-based converter for main power conversion and two separate transistor-based converters for reactive power management. Each converter is independently controlled and optimized for its specific function. This segmentation allows the complex task of reactive power management to be divided into manageable components, making the overall system more controllable and easier to maintain despite the increased number of elements.
Solution Approach 2:
The transistor-based converters act as intermediaries between the AC grid and the thyristor-based converter, managing reactive power flow and voltage stabilization. By introducing these intermediary devices, the system can handle reactive power compensation without directly complicating the core thyristor-based power conversion process, thereby managing complexity through functional layering.
3Reliability
If the starting sequence progressively increases DC system voltage using the hybrid system, then safety is improved, but the time required for startup increases
Solution Approach 1:
Before the electrolyzing process begins, the transistor-based converters are activated to pre-compensate for reactive power and stabilize the DC system voltage. The first transistor-based converter is switched on in capacitive reactive power mode, and the second is switched on in inductive reactive power mode, preparing the system in advance. This preliminary action ensures that when the thyristor-based converter increases the DC voltage during startup, the reactive power is already managed, enabling safer and faster startup by preventing voltage instability and reducing the time needed for gradual voltage increase.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method of controlling a starting sequence for a power supply device (12), wherein the starting sequence comprises: - activating operating of a thyristor-based converter (22), - activating operating of a first transistor-based converter (24) by keeping a first DC switch (38) in an open status, operating in a capacitive reactive power modus, - activating operating of a second transistor-based converter (26) by keeping a second DC switch (44) in an open status, wherein the second transistor-based converter (26) is operated in an inductive reactive power modus, wherein a second DC voltage is provided at the DC side (42) of the second transistor-based converter, - comparing the increased DC system voltage with the second DC voltage, and, dependent on the comparison, switching the second DC switch in a closed status, stopping providing inductive reactive power and activating a power supply modus of the second transistor-based converter.