Research On Control Strategy Of Shore Power Supply

China is a big trading country,every day,ships from all over the world traveling to China’s major ports will produce large quantities of harmful substances that pollute the environment when generating electricity itself.With the increasing demand for protection and improvement of the environment,more and more attention has been paid to solving the pollution problem of ships during port operations.In this context,the ship shore power technology came into being.Because of the different frequency,the 380V/50Hz AC power in China can not directly supply the low-voltage ships which are mostly 440V/60Hz abroad.So it is necessary to use the converter system to rectify and invert.The core of the ship shore power supply is the control of the converter system,and the quality of the converter system depends largely on the control strategy adopted.This thesis,based on the research of the control strategy of the low voltage ship power supply,designs different control strategies for the power source converter system both for off-grid operation and parallel operation mode.In the end,the AC system of 380V/50Hz of China is converted to the 440V/60Hz electric system to meet the demand of the 60Hz frequency low voltage ships.As for the off-grid operation mode,a dual closed-loop control strategy based on feed-forward decoupling is adopted.Through the establishment of model,coordinate transformation,feed-forward decoupling,double closed-loop control and so on,it will finally reduce the harmonic pollution effectively to the power grid while completing voltage level and frequency conversion and outputting high quality shore power energy.As for the parallel operation mode of the uninterrupted grid switching between the shore power and the ship power,because of the different characteristics of shore power supply and the diesel generator,it is necessary to design a new control strategy for the inverter link,so this thesis proposes a grid control strategy based on virtual synchronous generator,thus effectively solve the problem of shore power and Marine electric parallel operation.Finally,simulation experiments of off-grid and parallel operation of two modes of shore power supply are carried out in MATLAB/SimuLink simulation environment to verify the correctness of the control strategy.