Research Seminar: Sarath Tennakoon

April 30, 2025

2:30 p.m. - 3:30 p.m. CAT

A203

Power Electronics Revolution in the Power Grid and Electric Transport

Abstract: In the traditional Interconnected electric power system, the grid operator has no or very little control over the power flows and the voltage levels at various points in the grid. In nature, water flows from high ground to low ground in paths determined by the terrain. In the interconnected power grid, the flow of electrical power finds the easiest path determined by the "impedance" of the lines. Power systems are now fragmented, different companies managing the generation, transmission and distribution which had taken away the ability of the utility operator to exercise some control by adjusting the "Reactive Power" delivered by the generators. The situation has been exacerbated due to the increase of "embedded generation" due to the proliferation of renewable energy sources in the power system. This causes enormous operational problems for the transmission and distribution system operators due to issues such as voltage rises, local power loops, and the reversal of power which may result in serious blackouts. One recent example is the recent island wide blackout in Sri Lanka which is attributed to the excessive power fed into the grid through excessive solar generation. The traditional solution is to strengthen the grid by adding new lines and power plants. This is expensive and fraught with problems associated with compliance with regulators environmental considerations, and visual impact. Obtaining planning permission for new lines or power plants can take many years. However, the power electronics technology can provide a cheaper elegant solution which can be retrofitted to the existing electricity supply systems. The three variables that determine the power flows and the voltage stability are voltage, Impedance and the transmission angle. These variables can be controlled through Power electronics. So, what is power electronics? Power Electronics is about control, conditioning and conversion of electrical power by power semiconductor switching devices. It is important to note that, in power electronics, power devices are always switched and never used in the so-called linear mode. You can think of this as a big brother of a digital system where tiny switches are switched between "high" and "low" states. Power devices are available at ratings of up to 10000 Volts and up to about 4000 Amperes. Switching at high power levels poses a whole new set of challenges which makes the power electronics technology so exciting. Large power electronic converters for converting ac to dc and vice versa with ratings up to 4000MW are now in commercial operation. Businesses on Electric transport, harnessing renewable energy, mini grids microgrids etc.are not possible without power electronic converters. I have been researching the application of power electronics to electric utilities for well over 35 years culminating in the futuristic dc grid which will pave the way for interconnecting large solar resources in Africa, large windfarms in the North Sea and the European grid. In the presentation, the challenges in the application of power electronics to the electricity grids and electric transport, the contribution made by me through research, development, technology transfer and dissemination will be explained leading to the current and future activities for making a significant contribution to CMU Africa and the African continent in general, by conducting high quality research, knowledge transfer, capacity development, developing CMU students through projects and internships, mentoring young professionals, and disseminating knowledge. My mission is to advance the power electronics technical know-how and the application in the African continent.

Speaker: Sarath Tennakoon

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