Reaearch On Control Stategy Of Shipboard Micro-source Inverter Based On The Droop Control

As traditional non-renewable energy depletion and environmental pollution are becoming more and more serious, in order to maintain the socio-economic order and sustainable development, more and more attention has been paid to clean and renewable energy. In this context, new energy generation will be the future direction of the development of green ship. Ship-microgrid is an effective way to use new energy on a ship. The stability of the micro-source inverter parallel operation system, the rational allocation of load, relies on a reasonable-source inverter control strategy. In this paper, suitable control strategy for micro-source inverter running in parallel to establish ship-microgrid is specified as follows:Firstly, the advantages and disadvantages of different inverter main circuits and filter topology were analysised, according to the characteristics of the ship power system, the topology of the inverter main circuit and the filter circuit was chosen, and the filter parameters were designed. Then the mathematical model of micro-source inverter AC side, the modulator and inverter main circuit in diffirent coordinate were established. Since the output voltage strategy and output impedance of an inverter always have an important influence on the inverter parallel system and power distribution. The instantaneous voltage closed-loop control in three-phase stationary coordinate and the inverter output voltage decoupling control strategy in dq rotating coordinate were analysised, in order to reduce variable numbers, while ensuring the inverter output voltage tracking with no difference to the reference voltage, the inverter output voltage control strategy base on quasi-proportional-resonant(Quasi-PR) controller in αβ coordinate was proposed, and the influence of the controller parameters on closed-loop transfer function of output voltage and inverter equivalent output impedance were analysised. Droop control can ahieve the reasonable distribution of power between paralled inverters, but the power allocation accuracy is influenced by the total output impedance of the inverter, in order to achieve impedance matching between paralleled inverters, the droop methord based on vritual impedance was proposed. Through virtual impedance, the overall output impedance of the inverter was improved. To improve the dynamic performance of the parallel system, the improved droop method is proposed by adding differential equations in the conventional droop function, the dynamic response of the parallel system was improved.Finally, according to the theory and methods introduced above, simulation models based on the Matlab/Simulink simulation platform was built. And simulation of micro-source inverter running in parallel to build a ship-microgrid under different conditions has been carried out, the simulation results demonstrate the effectiveness of the proposed control strategy.