Conditioning and Saving Ship Electrical Energy at Electromechanical Transient Aboard

The paper deals with theoretical aspects of a ship electrical energy saving and minimization of voltage distortion of a ship electrical power system at the induction motor (IM) drive electromechanical transient aboard. The system is featured by stand alone generator station of commensurable with load output power, relatively high short-circuit impedance and nonlinear power circuits of converter fed motor drives. It is shown the increase of load currents during electromechanical transient results in voltage sags, distortion of the supply voltage waveform and the growth of harmonic contents. The deeper sag the longer start up process and longer impact to a ship electrical system. To minimize transient the detailed analysis and computer simulation of the IM across -the-line start up with the method of separate switching on stator windings is carried out to determine the time instants of the aboard voltage to be impressed. Results of the transient minimization and energy saving are readily implemented within thyristor soft starter structures by modernization of their control circuits.