Research On Control Technology For Both Grid-connected And Islanded Operations In Micro-grid Based On Micro-turbine

In recent years,with the development and application of new energy technologies,as well as the increasing demand for electricity all over the world and the coverage area is more and more complex,micro-grid has attracted attention as a unique way to efficiently use a variety of clean and sustainable distributed power sources for power generation.Micro-turbine with clean fuel is the most widely used and mature distributed power source on the market,so it is of great significance and value to study the grid-connected/islanded operation control technology of micro-grid distributed generation system composed of micro-turbine.The grid-connected and islanded operation control issue of micro-grid based on micro-turbine is divided into four sub subject: the control of micro-turbine system,the operation control in grid-connected mode and islanded mode,the switch between grid-connected mode and islanded mode.Aiming at the control of micro-turbine system,Firstly,the operation mechanism of the micro-turbine system is analyzed,and the mathematical model of each component of micro-turbine system is established.Secondly,considering the importance of speed control part in the micro-turbine and the shortage of tradition control algorithm in increasingly complex industrial practices,based on the research of system identification theory,generalized predictive control algorithm and particle swarm optimization algorithm,an improved adaptive generalized predictive control based on partical swarm optimization for the micro-turbine speed controller.Finally,through the simulation,it is proved that the speed controller designed in this paper can keep the speed of micro-turbine at the rated value when the load condition of the system is changed in a wide range,which ensuers the stable operation of the micro-turbine control system.Aiming at the operation control in grid-connected mode and islanded mode,a hierarchical decentralized coordinated control strategy based on multi-agent technology for micro-grid is proposed in this paper.Firstly,the lower-level decentralized controller based on constant power control strategy is designed for the grid-connected operation mode of micro-grid.Secondly,the lower-level decentralized controller based on improved virtual synchronous generator control algorithm is designed for the islanded operation mode of micro-grid.Finally,the upper-level coordination controller based on fuzzy control algorithm is designed for micro-grid system.The simulation results show that the balance of power supply and demand can be realized in grid-connected operation mode,and the stablility of voltage and frequency can be maintained in isanded operation mode,so as to ensure that the safe and stable operation of micro-grid system.Aiming at the problem of switch between grid-connected mode and island mode,islanded detection agent,grid-connected detection agent and pre-synchronization control agent are designed in this paper.In order to achieve smooth switching between two operation modes,an adaptive switching control strategy based on PQ control and VSG control is adopted in this paper.The simulation proves that the micro-grid system can achieve smooth switching between the grid-connected operation mode and the islanded operation mode.