Fixed-pitch Propeller Variable Frequency Ac Shaft Generator

Because the fuel expense accounts for total shipping operation cost of 50~60%, every shipping companies have taken actions to reduce operation cost resulting from energy consumption, consequently getting higher benefit. In general, the marine diesel engines can produce rated power of 10~15% in reserve, which drive a shaft generator to satisfy the normal sailing needs of electric power. The shaft generators have been applied on board the ships more and more commonly as energy-saving installation.There are two types of shaft generator, according to their installation, one installed with CPP and the other with FPP. For the latter, the speed or frequency compensation devises should be used in conjunction to maintain the generator's frequency. Nowadays, the common application of compensation devices is an externally commutated thyristor inventor.The problems present of shaft generator with FPP are: (1) lower of efficiency; (2) higher of building fee; (3) existing of ultra-harmonics. To overcome these, variable-frequency shaft generator system can be used. This system operates on the principle of main engine driving main engine driving simultaneously an A.C. synchronous generator and FPP through a double-speed gear box, that means an A.C. variable-frequency shaft generator.This dissertation analyses the reliability and economy of the A.C. variable-frequency shaft generator。This dissertation analyses the reliability of ship power station on each shipping movement, including normal sailing condition and maneuvering, through theoretical analysis simulating tests and dealing with the date measured. The variation of generator frequency, voltage and output caused by main engine speed increasing and decreasing is also analyzed here. When variable compounded system may be used, with the result of the same decreasing of bus-bar voltage and lowering of generator speed. When the variation of bus-bar voltage and frequency occurs, the reliability of electric motors, transformers, control and protection system is analyzed in this thesis. In addition, an additional device used for increasing the operational reliability of shaft generators is introduced.This dissertation analyses the economy of the application of the A.C. variable-frequency shaft generator, from the reduction of energy consumption, fuel expense accounts, building fee, and maintenance costs.With the conclusion of this dissertation, the A.C. variable-frequency shaft generator on FPP can operate reliably, and it is economical..