Research On Low Voltage Parallel Technology Applied In Ship Energy Management System

With the rapid development of power electronics and automation control technology,the integrated ship power system with electric propulsion as the core has become the trend of today's ship power system.Integrated power system realizes unified management of ship power grid energy,which helps to improve the combat effectiveness and vitality of the ship,the low-voltage power grid is mainly composed of inverters that inverts the medium-voltage DC power grid,which provide power for the low voltage equipment on the ship.In order to ensure the stability of low-voltage power supply,it is necessary to study the control of three-phase inverter and the parallel control of inverter.In this paper,the three-phase full-bridge inverter is analyzed,and a rotating coordinate system model is established and decoupled for its output voltage and current,based on the decoupled model,voltage and current double closed loop control is adopted,which verify the control effect has good stability and dynamic response through simulation.After completing the output voltage and current control of a single inverter,this paper calculates the active power and reactive power of inverter output in the inverter parallel system,and analyzes the traditional droop control curve of the inverter under different output impedances in the inverter parallel system,then points out the defects of traditional droop control,so that an online adjustment virtual complex impedance based on CAN communication is proposed,the main purpose is to make the output impedance as inductive as possible,and balance the inverter load voltage caused by different line impedances,achieve the effect of suppressing the circulation.The virtual complex impedance compensation voltage is introduced in the reactive droop characteristic to improve the reactive power/voltage amplitude droop curve,so that the voltage drop can be reduced during the regulation of reactive power and improve the load capacity of the system.Finally,the hardware design in the experiment is explained,and the software flow is introduced.The test of parallel inverter shows the correctness of control strategy.In a test platform,a parallel test of two 1MW inverters is completed,according to the working waveform analysis,the correctness of the control strategy is indicated.