Shore Power Combiner With Isolation Transformers
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Solution Overview
Problem
The widespread use of ground fault circuit interrupters (GFCIs) in dock environments has rendered previous methods of paralleling multiple shore-based AC power sources unsafe, as GFCIs interpret this configuration as a ground fault and interrupt the current, preventing the combination of lower-capacity sources into a higher-capacity source for larger vessels.
Innovation Solution
The system employs isolation/polarization transformers and a combiner device with a microcontroller to continuously monitor and control the characteristics of multiple shore power sources, safely combining them only when conditions are met, and preventing voltage backfeed, using communication networks like LAN, Wi-Fi, or Modbus RTU for remote monitoring and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple lower-capacity shore-based AC power sources are paralleled to provide higher current for larger vessels, then the available electrical power increases, but ground fault circuit interrupters (GFCIs) interpret this configuration as a ground fault and interrupt the current
Solution Approach 1:
The patent introduces an adapter as an intermediary device between multiple shore-based power sources and the vessel's electrical system. This adapter includes isolation transformers for each power source, which electrically isolate the paralleled sources from the vessel's ground reference. The isolation transformers allow multiple lower-capacity sources to be combined into a higher-capacity source without triggering GFCI ground fault detection, thereby maintaining both increased power availability and continuous current flow.
2Power
If an adapter with isolation transformers is used to parallel multiple shore power sources, then the available current increases, but the device complexity increases
Solution Approach 1:
The adapter is segmented into modular components, with each shore power source connected to a dedicated isolation transformer and control circuit. This segmentation allows for easier installation, maintenance, and troubleshooting of individual components without affecting the entire system. Each module can be independently configured and tested, reducing the overall complexity management despite the increased functional capability.
3Power
If multiple power sources are combined without proper monitoring, then the power availability increases, but hazardous electrical conditions such as voltage backfeed may occur
Solution Approach 1:
The patent incorporates monitoring circuits that continuously measure electrical parameters including voltage, current, and phase relationships of each connected power source. The system provides feedback control to detect unsafe conditions such as voltage backfeed, phase conflicts, or ground faults. When hazardous conditions are detected, the monitoring system automatically disconnects the affected power source through protective relays, thereby maintaining power availability from safe sources while eliminating electrical hazards.
Solution Approach 2:
The system performs preliminary safety checks and establishes protective measures before combining multiple power sources. Isolation transformers are configured with built-in protection against backfeed, and the control system pre-establishes disconnection pathways for each power source. This preliminary anti-action prevents hazardous conditions from developing by having protective mechanisms already in place before operation begins.
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 allows for the safe and automatic combination of multiple shore power sources into a single higher-current source, preventing hazardous electrical conditions and enabling better current repartitioning, while avoiding GFCI activation, thus providing reliable power to larger vessels in inadequate dockside electrical services.
Implementation Method 1
The systems pass the power from each shore-based source through a dedicated isolation/polarization transformer for that source
Data Source
AI summary
Systems and methods are provided for continuously and automatically monitoring, controlling, and combining shore-based AC power sources for waterborne vessels while the vessels are at dock or in port. The systems can allow a one or more shore AC power AC to power the entire vessel, and automatically and safely join multiple power sources to power a single higher-current-capacity electrical distribution bus on the vessel. The systems can automatically monitor and evaluate the characteristics of multiple shore power sources to determine when it is possible to safely combine the sources. Also, the systems can recognize the disconnection/disablement of a shore power source, and can un-combine that power source from the other power sources feeding the system. The systems can automatically evaluate the phase, current and voltage of multiple AC sources, and combine the sources only after a specific set of conditions are satisfied.