In a significant stride towards enhancing power quality in cold ironing (CI) systems, a team of researchers led by Cheikh Abdel Kader from the Department of Physics at the University of Nouakchott in Mauritania has developed a novel model-free control strategy for modular multilevel converters (MMCs). This innovation, published in the journal Applied Sciences (translated from French), promises to bolster the robustness and efficiency of power supply systems for moored vessels, a critical aspect of modern maritime operations.
Cold ironing, or shoreside electricity, is a process that allows ships to turn off their auxiliary engines while in port and plug into the local power grid. This practice not only reduces air pollution but also cuts down on greenhouse gas emissions. However, ensuring a stable and clean power supply to meet the varying demands of different vessels has been a persistent challenge. The International Electrotechnical Commission (IEC), International Organization for Standardization (ISO), and Institute of Electrical and Electronics Engineers (IEEE) standard 80005-1 sets stringent guidelines for power quality in CI systems, emphasizing the need for high power at standardized voltages with minimal harmonic distortion.
The research team tackled this issue by proposing an intelligent proportional-integral (iPI) corrector with adaptive gain, applied to a three-phase MMC equipped with an LC filter. This architecture, designed for distributed infrastructures, reduces the number of transformers required while maintaining high output voltages. The iPI strategy enhances system robustness, dynamically compensates for disturbances, and ensures superior power quality.
To validate their approach, the researchers conducted a comparative analysis of three control strategies—proportional-integral (PI), intelligent proportional-integral (iPI), and intelligent proportional-integral adaptive (iPIa)—using MATLAB/Simulink simulations. They also performed experimental tests on the OPAL-RT platform. The results were impressive, showing a significant reduction in total harmonic distortion (THD) by 1.18%, in line with the IEC/ISO/IEEE 80005-1 standard.
Cheikh Abdel Kader explained, “Our model-free control strategy addresses the critical need for high power quality in cold ironing systems. The iPI corrector with adaptive gain dynamically compensates for disturbances, ensuring a stable and clean power supply for moored vessels.”
The commercial implications of this research are substantial. Port authorities and shipping companies stand to benefit from improved power quality, leading to reduced equipment wear and tear, lower maintenance costs, and enhanced operational efficiency. The reduction in harmonic distortion also means compliance with international standards, which can open doors to new markets and partnerships.
Moreover, the adaptability of the iPI strategy to distributed infrastructures offers a scalable solution that can be tailored to the specific needs of different ports and vessels. This flexibility is crucial for the maritime sector, which is increasingly focused on sustainability and operational excellence.
As the maritime industry continues to evolve, innovations like the one developed by Cheikh Abdel Kader and his team will play a pivotal role in shaping the future of cold ironing systems. By ensuring high power quality and system robustness, this research paves the way for more efficient and environmentally friendly maritime operations. The findings, published in Applied Sciences, underscore the importance of advanced control strategies in meeting the demanding requirements of modern CI systems.