Research On Frequency Starter And SVG Integration Apparatus Used In Marine Electric Propulsion System

Electric power propulsion system has been widely used in machinery system.Considering the features of ship power station, sensitivity to the environment andseparating from the grid, the power converter should have better performance. Onone hand, the power converter should improve the starting performance, keepingstarting current within its proper bounds and reduce its impacts on voltage andfrequency of the ship power station. On the other hand, the converter should becontrolled properly to improve ship power station quality, reducing the reactivepower pollution and improving its power-factor, during its normal working hour.Therefore, the research on topology, control strategy, is of great significance both intheory and in practice.In view of problems of power converter above, this thesis proposed a novelflexible converter topology, in order to narrow down starting current, compensatereactive power. Based on the proposed converter topology, the thesis focused onanalyzing its operation principle, control strategy and performance, by simulationand experiment.Firstly, feasibility study was completed. The converter could operate in twomodes: frequency starter and static VAR generator, then the operation performanceand PWM control strategy of converter operating in both modes are analyzedrespectively. As for frequency converter, the rotor field oriented vector controlstrategy was used, which can realize variables decoupling control decrease thestarting current and improve the starting performance of the electric powerpropulsion system. Furthermore, the synchronous switching strategy stem fromphase-locked loop for flexible power converter was proposed, where the VCO isreplace of VFD. The soft switching operation principle was analyzed. At last, staticVAR generator based the instantaneous reactive power theory was analyzed; themeasurement strategy and control strategy of reactive current were analyzedrespectively. This operating mode of the power converter can improve powerefficiency of the ship power station and the stability of the voltage.Based on the proposal strategy above, the MATLAB/Simulink model was built.The simulations were carried out to demonstrate the effectiveness of this algorithm.Then the proposed flexible power converter system platform based on DSP was built,to verify the performance and control strategy of the proposed flexible powerconverter. The experiment results verify the feasibility and validity of flexible powerconverter and control strategy.