Multiwinding power transformers design features, the n-winding ideal transformer, 3-phase auto transformers, the transformer as a control device. High voltage direct current transmission HVDC: General aspects and comparison with AC transmission converter circuits, analysis of bridge converters, converter charts, harmonics and filters, ground return. Reactive power control. Reactive power control: Load compensation, steady state reactive power control in transmission System, effect on power system. Dynamics, static compensatory, series capacitors, syn. condensers, reactive power coordination. Power system harmonics, sources, system response to harmonics, harmonic pollution in networks, methods of analysis, standards and limits.