OTC 21467--Pressure Tolerant Power Electronics for Deep and Ultra-Deep Water

摘要

This paper presents results from an on-going research project [1] on pressure tolerant power electronics. The main goal for the research is to provide and demonstrate solutions that enable power electronic converters to operate in pressurized environment. Oil companies have plans for subsea processing of oil and gas. Today’s concept considers power electronic converters in one bar vessels. As the depth and the converter power rating increase, these vessels become increasingly bulky and heavy. Pressure balanced converters would allow lower vessel wall thickness, thereby giving lower weight, and simpler cooling due to improved heat conduction through the vessel walls. The new concept considers the power electronic converters placed in vessels completely filled with appropriate dielectric liquid able to operate at pressures from 1 bar up to several hundred bars. Dielectric fluids are required to prove their properties especially related to insulation, incompressibility and heat transportation. The methodology presented here considers a mechanical adaptation of components followed by various laboratory experiments for verifying or correcting the proposed solutions [2-4]. Standard off-the-shelf components and special pressure adapted components have been subject to various provocative pressurisation tests up to 300 bar. Tests clarified the need for special adaptation of some components, while others could be used without any modification. Subsequently a full converter phase-leg has been built, submerged in dielectric liquid and tested in full operation up to 300 bar. This phase-leg is based on a press-pack IGBT modified for operation at high pressure. Measurements performed at different pressures demonstrate that there is no relevant difference in terms of electric parameters between this modified IGBT and a standard IGBT. Long-term tests proved the concepts goodness. The next step will test bonded IGBT technology in high-pressure environment, and finally will realise a test demo to be located at a suitable subsea site.