The shift to electric propulsion is driven by decarbonization targets and the demand for higher operational efficiency. Key trends reshaping the marine power grid include:
The Rise of the Integrated DC Grid (Direct Current Grid)
Modern ships are increasingly adopting DC grids over traditional AC systems.
Benefits: DC systems eliminate the need for large main transformers and complex synchronization, saving weight and space. They allow for superior integration of battery energy storage (BESS) and variable-speed generators.
Transformer Evolution: This transition shifts the transformer's role from a simple line-frequency component to a specialized AC-DC Converter or Solid-State Transformer (SST) component, providing high-frequency galvanic isolation between different voltage sections of the DC bus.
Hybrid and All-Electric Propulsion
Vessels use a combination of power sources (engines, batteries, fuel cells).
Requirement: This requires the ability to step up high-voltage power from the main generators and step down to various usable voltages (e.g., $6.6\text{kV}$ down to $450\text{V}$ for auxiliary loads or "hotel power").
Transformer Role: Distribution transformers are indispensable for creating these various voltage islands for different onboard systems (propulsion drives, bow thrusters, and low-voltage loads).
2. The Core Role of Marine Transformers in the Electric Transition
Transformers are vital at three critical levels: Propulsion System Integration, Power Quality Protection, and Safety/Isolation.
Role
Function in Electric Propulsion
Key Technology
I. Harmonic Mitigation
To protect the ship’s main grid (generator and switchboard) from harmonic currents injected by large Variable Speed Drives (VSDs) for propulsion.
To match the high output voltage of the main power generation system to the specific input voltage required by the propulsion drive's power converters.
Propulsion/Drive Isolation Transformers.
III. Galvanic Isolation
To electrically isolate critical systems (like shore power connections or high-voltage drives) from the ship's hull and other circuits, preventing electric shock and galvanic corrosion.
Marine Isolation Transformers.
3. Top Developers' Strategies: Addressing Power Quality with Transformers
Top-tier suppliers like ABB manage the challenges of marine electrification, particularly power quality, by deploying advanced transformer technology:
️ Challenge 1: System Reliability and Harmonic Injection
The widespread use of power electronics (inverters and rectifiers) in electric propulsion causes severe harmonic distortion that can lead to overheating, equipment damage, and system instability.
Top Developer's Strategy: Multi-Pulse Transformation
ABB and others use Phase-Shifting Multi-Winding Transformers (e.g., 24-pulse configurations) at the front end of their propulsion drives.
Mechanism: The transformer creates a precise phase shift between multiple secondary windings. When the current from these phase-shifted windings is combined, the low-order harmonic currents (such as the 5th and 7th) are naturally canceled out.
Result: This ensures the power drawn from the ship's main grid has a significantly lower Total Harmonic Distortion (THD), complying with strict marine classification society rules.
⚡ Challenge 2: Harsh Marine Environment
Marine transformers must withstand severe operational stressors. All marine transformers—whether phase-shifting, distribution, or isolation—must be built to endure constant vibration, high humidity/salt fog, and extreme thermal cycling found in a vessel's engine room. Top developers rely on specialized design features (like integrated rigid structures and high-grade insulation) to ensure longevity and safety in this highly demanding environment.
By integrating these specialized transformers, developers can ensure that high-efficiency propulsion systems, like the Azipod®, operate safely and reliably without compromising the integrity of the ship's overall power grid.
4. How CEEG Meets the Electrification Trend as a Significant Emerging Force
Leveraging extensive experience collaborating with renowned manufacturers such as ABB, Siemens, and Fuji in producing phase-shifting rectifier transformers for 24-pulse and 36-pulse frequency converters, CEEG has developed 12-pulse and 24-pulse phase-shifting rectifier transformers specifically designed for marine electric propulsion systems. Furthermore, Our expertise in marine transformer design enables transformers to successfully tackle the challenges posed by harsh marine environment. CEEG stands as an emerging force in meeting this significant electrification transition.
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