Frequency Converter Bypass for Short-Circuit Localization
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Solution Overview
Problem
Existing methods for feeding electrical power from a supply network to a consumer network, such as those used for ships in port, struggle to sustain high short-circuit currents for an adequate duration, which is necessary to localize and separate short-circuit faults, due to the risk of damaging power semiconductor valves in frequency converters.
Innovation Solution
A method and device that utilize a frequency converter connected to both the supply and consumer networks, with a switching unit in parallel to bypass the frequency converter during short-circuit events, and control means to detect short-circuit currents and actuate the switching unit, ensuring the short-circuit current flows through the switching unit, which has sufficient current-carrying capacity and quick switching capabilities to prevent damage to the frequency converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frequency converter is used to couple the supply network and consumer network, then voltage and frequency conversion is achieved, but high short-circuit currents cannot be fed into the consumer network for a sufficiently long period due to damage risk to power semiconductor valves
Solution Approach 1:
The system is segmented into two parallel paths: the frequency converter path for normal operation and the switching unit path for short-circuit conditions. This segmentation allows each component to be optimized for its specific function, with the switching unit handling high short-circuit currents while the frequency converter handles controlled power conversion.
Solution Approach 2:
The switching unit acts as an intermediary component that bridges the supply network and consumer network during short-circuit events. It temporarily takes over the current path, protecting the frequency converter from direct exposure to damaging short-circuit currents while still enabling fault detection and isolation.
2Strength
If the switching unit is actuated quickly to protect the frequency converter, then damage is avoided, but the duration may be insufficient to localize and separate the short circuit
Solution Approach 1:
The switching unit provides dynamic response by rapidly transitioning between open and closed states based on real-time detection of short-circuit conditions. This dynamic capability allows the system to protect the frequency converter immediately while maintaining sufficient current flow duration for fault localization through coordinated control.
3Reliability
If a bypass switching unit is added to the frequency converter, then high short-circuit currents can be fed for sufficient duration, but the device complexity increases
Solution Approach 1:
The switching unit is designed with multi-functionality, serving both as a protective bypass for the frequency converter and as a controlled current path for fault detection and isolation. This universal design reduces the need for separate dedicated components, thereby limiting the increase in overall device complexity.
Data Source
AI summary
In order to provide a device (1) for feeding a consumer network (13) with the electric power of a supply network (12), wherein the device (1) has a frequency converter (2) which may be connected both to the supply network (12) and to the consumer network (13), by means of said frequency converter high short-circuit currents may also be provided over a sufficiently long time duration for the consumer network such that a short-circuit is localized in the consumer network and may be selectively separated from the remaining, error-free consumer network, the invention provides a switch unit (13), which is disposed parallel to the frequency converter (2) and configured for bypassing the frequency converter (2), and a controller (9) that is connected to the switch unit (3), said switch unit (13) and controller being equipped to actuate a switch unit (2) upon detection of a short-circuit current flowing across the frequency converter (2).