METHODS TO IMPROVE THE QUALITY OF ELECTRICAL SUPPLY OF SHIP SYSTEM WITH NONLINEAR LOAD
Abstract
Modern electromechanical systems with static power converters significantly impair the
quality of electric power due to the appearance of harmonic distortion of the current and voltage of the
mains. The most important issue is the quality of electricity for autonomous power grids with a finite power,
namely, such is the ship's electrical network. The traditional method of improving the shape of current and
voltage is the passive filtering method, based on resonance phenomena. In work researches on use of the
passive filter calculated on concrete ship loading are spent. The investigations were carried out on an
experimental stand assembled in the laboratory of electromechanical systems of the ship electromechanics
and electrical engineering department of the National University "Odessa Maritime Academy". As a nonlinear load, an electric drive of a pump with an induction motor and a frequency converter of Mitsubishi
Electric, the FR A700 series with a power of 2.2 kW, which is powered by an autonomous power source of
commensurate power, is considered. In this paper, a technique is given for calculating the parameters of a
three-phase C-type filter, also structural features of constructing such a filter are described. The carried out
natural experiments made it possible to obtain oscillograms of currents and voltages of the electric network,
and to estimate their harmonic composition. A generalized indicator of the quality of the power grid, namely
THD was obtained for all typical operation modes of a pump electric drive using a C-type filter. The paper
gives recommendations on the use of C-type filters to improve the quality of the autonomous power network.