Research On Inverter Grid-connected Technology For Ship Integrated Power System

With the rapid development of large-capacity power electronics and artificial intelligence,the ship’s integrated power system has gradually become the current ship’s power grid due to its higher operating efficiency,better maneuverability,and better concealment.Major trends.Among them,the ship’s low-voltage power grid mainly passes the medium-voltage direct current to the inverter,and together with the auxiliary generator and shore power supply,provide power for the ship’s low-voltage equipment.However,due to the significant differences in energy density and equipment operating environment between the marine power grid and the land power grid,many of the grid connection strategies of the land power grid cannot be reproduced in the marine power grid.Research and optimize the control of marine three-phase inverter and its grid connection technology.In this thesis,a three-phase inverter for ships is used as the main research object,and targeted research is carried out on the grid-connected technology of the integrated power system for ships.The grid-connected technology is based on the mathematical model of the marine inverter,and adopts the improved droop control technology based on virtual impedance to achieve the frequency and voltage regulation and power distribution of the marine inverter.Three inverters in parallel,inverter and auxiliary power grid connection,inverter and shore power switching,design corresponding grid connection processes,optimize communication technology in grid connection,and design grid controller Finally,through the test verification,the research on the grid connection technology of the ship’s integrated power system inverter was completed.The key research contents of this article are summarized as follows:Coordinate transformation analysis was introduced to establish the three-phase inverter mathematical model,and the mathematical model was decoupled from the voltage and current double-closed loop.The equivalent block diagram of the voltage and current after decoupling was deduced,and then the equivalent block diagram was established based on the equivalent block diagram.Single inverter simulation model.Aiming at the consistency of the grid connection strategy of the three operating conditions of the inverter,a parallel model of two inverters is used to study the droop control strategy based on virtual impedance,and the method of CAN reactive power distribution is proposed online.Power to optimize the grid connection strategy.According to the characteristics of the network equipment,design their own processes and introduce them.Aiming at the problem that the inverter’s grid-connected communication is susceptible to interference,the cause of the interference is analyzed,and the electromagnetic interference suppression is proposed from three aspects:interference source,coupling path and sensitive equipment.The hardware design and software construction of the grid-connected controller for ship inverters are introduced,and the status and role of the controller in the ship’s integrated power system are explained,as well as the way in which the controller interacts with other equipment data.Based on a ship experimental platform,the above-mentioned inverter grid connection strategy and grid connection process were tested and verified.A series of voltage and current data were obtained using a high-precision data acquisition system,and the test results were plotted and analyzed by graphics.