Research On Stable Operation Of Parallel Switching Of Marine Diesel Synchronous Generator And Low-voltage Shore Power

The purpose of ship shore power supply is to provide the system of electric energy for the ship after landing.It can reduce the emission pollution of marine diesel engine and realize the efficient utilization of resources.It is an important research content of ship new energy.In recent years,it is widely used in civil and military ports and docks of various countries.As the design of ship shore power will affect the stability and efficiency of the subsequent connection between shore power and ship,therefore,in order to realize the stable operation of parallel switching between shore power and ship,how to complete the fast connection and switching between marine diesel synchronous generator and low-voltage shore power is considered in this paper.Firstly,the voltage,frequency and phase of two marine synchronous generators are detected on the basis of the study of the single marine diesel synchronous generator established by the park transform and the per unit method.The synchronous parallel module is used as the parallel model of the two diesel synchronous generators.Based on the analysis of the cause of the power mutual oscillation and the traditional solutions,the angle velocity variation and the power variation are collected as the control variables in PID control is putted forward in the paper to adjust the power oscillation.The simulation results in Matlab/Simulink show that the method proposed in this paper can realize the parallel stable operation of two diesel synchronous generators.At the same time,compared with the control strategy without control,the control strategy proposed in this paper can effectively eliminate the power interactive oscillation and verify its effectiveness.Secondly,in the control strategy of ship shore power supply based on virtual synchronous generator,power controller and excitation controller are used to simulate the characteristics of the motor to realize the uninterrupted connection between diesel synchronous generator and shore power.In order to solve the voltage drop and frequency oscillation caused by different marine diesel synchronous generators and ship shore power in the connection process,since the reactive power voltage link in the excitation controller determines the voltage change,the voltage feedback control is used to improve the reactive power voltage link so as to eliminate the voltage drop;because there is a linear relationship between inertia and frequency,Then the adaptive virtual control of inertia is introduced to change the inertia value to suppress the frequencyoscillation.In the Simulink simulation,the voltage and frequency output results of single control strategy,traditional control strategy and comprehensive improvement are compared.The experimental results show the effectiveness of the proposed control strategy.Finally,the parallel switching operation simulation of marine diesel engine and low-pressure shore power is carried out,and the output conditions of single marine diesel engine and two marine diesel synchronous generators are compared with shore power when they are parked and unloaded respectively.At the same time,the voltage and frequency output results of the improved shore power control strategy are compared.The experimental results show that the improved control strategy of shore power supply based on VSG can realize the stable operation of uninterruptible parallel switching.