Conference Agenda

This research studied the physicochemical and charge transport behaviour of composite natural esters derived from non-food grade oils for high-voltage insulation. Crude neem oil and palm kernel oil were purified and subjected to epoxidation, converting unsaturated carbon-carbon double bonds into stable epoxide rings, confirmed by Fourier Transform Infrared Spectroscopy. Purified palm kernel oil was further transesterified to reduce viscosity before epoxidation. Composite oils were synthesized by blending epoxidized neem oil with epoxidized palm kernel oil methyl esters in varying proportions. The physicochemical and dielectric properties were analyzed. The viscosity of the base oils and their blends show temperature dependence and there is also an improvement in the viscosity of the base neem oil with increase in the concentration of epoxidized palm kernel oil methyl ester. The optimum blend shows a viscosity less than that of mineral oil at transformer operating temperature. This is indicative that the optimal blend has a better heat transferability. Dielectric study revealed frequency dependent behaviour typical to DC conduction at high frequencies and at low frequencies below a characteristic frequency showing charge transport typical to interpolar polarization. The developed composite oil exhibits improved heat transfer property than the base neem oil. Its dielectric properties show similar behaviour as that of mineral oil, however, it has higher loss factor.

Wind turbines are critical components of renewable energy infrastructure, but they face operational challenges due to transformer, generator and powertrain defects. One cause of the defects is nacelle circulating currents. In this paper we will discuss how these currents impact generator stator and rotor insulation systems, gearbox gear and bearing, and main bearing reliability. The multi-year collaborative study included mapping circulating currents and component impacts as well as solutions attempted by OEMs, owners and vendors. Generator and transformer insulation defects related to circulating currents will be identified along with gearbox and main bearing discharge currents and the source of the circulating currents and their flow. The paper will explore mitigation strategies such as improved grounding and insulating techniques for these components for both on and off-short wind turbines.