Modelling of Power Electronics Reliability for Offshore Floating PV Applications

Power electronics (PE) play a crucial role in photovoltaic (PV) systems by managing the conversion and control of electrical energy generated by solar panels. Deploying energy systems at sea, particularly offshore photovoltaic (OFPV) installations, presents significant challenges impacting energy yield and system reliability. Key issues include the dynamic and harsh marine environment, where wave-induced movements, salt deposition, algae growth, and bird droppings which degrade system performance and reliability. Moreover, nearby wind turbines introduce dynamic shading effects, reducing the efficiency of the power conversion system. An unexpected failure of PV converters disrupts the PV plant operation, causing significant financial losses. The mission profile in power electronics includes all the operating and environmental conditions to which the inverter system is subjected, such as current, voltage, varying temperatures, irradiation, moisture, shading, and others over time. In floating PV applications, the stressors are more diverse and intense than in conventional PV systems, making it essential to research to understand the degradation pathways of the PV converters under these varying mission profiles and the impact of their reliability and lifetime. 

Statistical data in the literature report inverter failure tickets, costs, and the number of tickets per component. However, actual failure mechanisms causing the degradation are rarely specified. Moreover, different lifetime models, including empirical, physics-based, and data-driven models, exist to predict wear-out in power electronics. However, these models are either complex to use, e.g. physical models, or the stress level applied during accelerated testing, e.g. to derive empirical models, does not induce the same degradation modes of a PV converter in operation. The correlation between measured stressors and degradation is necessary to understand the degradation pathways and to develop hybrid reliability modelling techniques for an accurate lifetime estimation of PV converters. The objective of this project is to create a hybrid lifetime model for power electronics based on the mission profiles in a marine environment. Validation work can also be conducted at EnergyVille, where PV converters can be monitored indoors using solar emulators and climate chambers enabling the in-house control of mission profiles, including humidity, temperature, UV exposure, and mechanical load. 

The successful candidate will begin with a comprehensive literature review on lifetime prediction techniques for power electronics (switching devices, capacitors), including physics-based, empirical and data-driven techniques. Then, a hybrid technique will be developed, combining at least two categories (e.g. empirical, physics-based). Simulations will be conducted in PLECS, Simulink-MATLAB and COMSOL to simulate thermal loads under varying environmental conditions. The PV output will be simulated using imec’s Energy yield simulation framework, where the impact of floating structure design, wind turbine shadow flickering, and temperature fluctuations will be analyzed. 

The work will be at EnergyVille, Genk, within the Energy Systems team.  

Skills required: Good comprehension of scientific articles, electrical/ materials engineering background. Good knowledge of power electronics and circuit simulation software such as PLECS.