The Harmonic Analysis And Suppression Research Of Marine Electric Propulsion System

The massive application of power electronic technology made a great development to the electric propulsion technology, but it also caused the harmonic problems to the ship power system. The harmonics lead to larger equipment volume and more transmission loss, deteriorate the power supply quality, and then affect the safety and economical running of power equipments. The harmonic problems have become more and more serious, now it is an urgent task to manage and control harmonics within limits.This dissertation makes a summary of the electric propulsion technology, summarizes harmonic problems about power system of marine electric propulsion and the harmonic suppression methods, and especially introduces the technology of multiphase rectification which is the most widely used in the ship building industry. At the same time, it also does corresponding simulation according to a large-scale LNG ship, which is using 24-pulse rectification. Two electric propulsion ships which have been built and used different methods to suppress harmonic are analyzed and compared. It is expected that this dissertation can provide some references to the design of power system of the electric propulsion ship.The research work can be concluded as follows:(1) This dissertation makes a summary of the electric propulsion technology. (2) Discusses the harmonic phenomena, and its sources, effects, limiting standards and control methods of power system on electric propulsion ship.(3) Analyzes the harmonic suppression methods and related technology, especially researches the technology of multiphase-commutate which is the most widely used in the ship building industry.(4) Take a large-scale LNG ship with 24-pulse rectification as example, the control methods are discussed.(5) Does analysis and comparison with two electric propulsion ships which have been built and used different methods to suppress harmonic.